WO1991007167A1 - Protein kinase activators as enhancers of melanin production - Google Patents

Abstract

A method of enhancing in vivo melanin production is disclosed. The method comprises topically applying an effective amount of at least one Protein Kinase C Activator to the surface of the skin. Also disclosed is a composition for enhancing in vivo melanin production. The composition comprises an effective amount of at least one Protein Kinase C Activator in combination with at least one physiologically acceptable solvent. The composition may optionally contain at least one other ingredient selected from the group consisting of: riboflavin, riboflavin phosphate, mixtures of riboflavin and riboflavin phosphate, DOPA phosphates, sunscreening agents, emollients, emulsifiers, solvents for sunscreening agents, waxes, thickeners, film formers, humectants, antioxidants, preservatives, surfactants, perfumes, biological additives, buffering agents, chelating agents, emulsion stabilizers, opacifying agents, pH adjusters, propellants and coloring agents. The Protein Kinase C Activators in the methods and compositions of this invention can be selected from the group consisting of: diacylglycerols, triacylglycerols, lipopolysaccharides, unsaturated free fatty acids, saturated short chain free fatty acids, glycerolphospholipids, enzymes which hydrolyze glycophospholipids to diacylglycerols, and bryostatins.

Description

" PROTEIN KINASE ACTIVATORS AS

ENHANCERS OF MELANIN PRODUCTION"

REFERENCE TO RELATED APPLICATION

This application is related to copending application Serial No. 07/433,809 filed November 9, 1989, the disclosure of wnich is incorporated herein by reference thereto.

FIELD

This invention relates to the enhancement of melanin production by the topical application to the skin of at least on Protein Kinase C activator.

BACKGROUND

Melanin pigmentation is largely responsible for norma skin color and protection against ultraviolet damage, including photocarcinogenesis. Melanin is produced in melanocytes, neural crest derived cells situated in the basal layer of the epidermis, a is transferred via dendrites to surrounding keratinocytes, the mo abundant cell in the epidermis. Gordon et al. disclose that this anatomical relationship, termed the epidermal melanin unit, is envisioned as one melanocyte in contact with an estimated 36 keratinocytes in the basal and suprabasal layers. According to Gordon et al., the rates of pigment synthesis and transfer by melanocytes appear to be influenced by ultraviolet light exposure and by certain inflammatory processes, but the precise factors regulating human epidermal pigmentation are unknown. Gordon et al. also disclose that it is also unknown whether these stimuli act directly on melanocytes, keratinocytes, other cells that in turn release melanocyte mediators, or via both direct and indirect mechanisms. According to Gordon et al., the close physical contact and known functional interrelationship of the epidermal melanin unit make keratinocyte. mediation of melanocyte function an attractive hypothesis. See Gordon, P.R., et al., "Regulation of Human Melanocyte Growth, Dendricity, and Melanization by Keratinocyte Derived Factors", Journal of Investigative Dermatology, 92:565- 572, 1989.

According to Joshi et al., the primary events that are observed when human skin is exposed to ultraviolet radiation are immediate pigment darkening (a transient oxygen dependent photooxidation event), delayed sunburn, and tanning. Joshi et al. disclose that a wide variety of short-lived reactive oxygen species are known to be generated in skin photosensitization reactions in the presence of exogenous or endogenous photosensitizers such as riboflavin. Joshi et al. disclose an in vitro study of the role of reactive oxygen in photosensitization and tanning reaction using riboflavin (RF), hematoporphyrin (HP), 3-carbethoxypsoralen (3-CP), and 8-methoxypsoralen (8-MOP). Joshi et al. report that reactive oxygen produced by photosensitized RF, 3-CP, and 8-MOP was found to oxidize tyrosine and DOPA to dopachrome and subsequently their conversion to melanin. Joshi et al. also report that DOPA was oxidized to dopachrome and subsequently to melanin at a variable rate RF>3-CP>HP>8-MOP. According to Joshi et al., their observations appear to have relevance to the oxygen-requiring immediate tanning reaction of the skin stimulated by the UVA (320- 400 nm) portion of solar radiation and in the induction of skin photosensitization. See Joshi, P.C. et al., "Involvement of Reactive Oxygen Species in the Oxidation of Tyrosine and DOPA to Melanin and ln Skin Tanning," Biochemical and Biophysical Research Communications, Vol. 142, No. 1 , pp. 265-274, January 15, 1987.

Those skilled in the art will recognize that there is no data presented in the in vitro study of Joshi et al. that supports the authors inference that the in vitro photosensitization of tyrosine and DOPA to dopachrome also resulted in the subsequent conversion of dopachrome to melanin. It will be appreciated by those skilled in the art that the in vitro study of Joshi et al. relates to immediate tanning (IT) reactions, also known as immediate pigment darkening (IPD). IPD is a transient- phenomenon observed in the skin after irradiation that then fades away. Immediate tanning may begin immediately and fade within seconds to a minute or may persist with higher doses or longer exposures for 1/2 to 1 hour or up to 24 hours. Rarely, IT may persist for 36-48 hours after prolonged exposure, at which stage it blends with delayed tanning (DT). See Regan, editor, The Science of Photomedicine. pp. 241-242, 1982. According to Fitzpatrick et al., IT occurs within minutes of exposure to UVA (320-400 nm) and to visible light. Fitzpatrick et al. disclose that IT becomes most prominent within 1 hour of exposure and almost completely disappears within 4 hours.

Fitzpatrick et al. further disclose that studies with electron spin resonance have shown that IT reaction is probably an oxidation reaction that involves the generation of unstable semi-quinone-like free radicals in melanin. According to Fitzpatrick et al., DT develops 48-72 hours after exposure to UV light, and DT involves new production of melanosomes and therefore appears slowly over a period of days. See Fitzpatrick et al., editors, Sunlight and Man, p. 175, 1974. Thus, there is no disclosure nor suggestion relating to the in vivo effects of, for example, riboflavin on melanogenesis (tanning).

Farooqui et al. disclose that the activity of protein kinase C is altered by several lipids such as diacylglycerol, free fatty acids, lipoxins, gangliosides, lipopolysaccharides (diacylglucosamine 1 -phosphate) and sulfatides. According to Farooqui et al., these lipids may interact with protein kinase C either directly or through calcium ions and produce their regulatory effect (activation or inhibition) on the activities of the enzymes phosphorylated by this kinase. It is disclosed that the activity of tyrosine hydroxylase is increased by the phosphorylation by Protein Kinase C. According to Farooqui et al., Kishimoto et al. studied the structural requirement of diacylglycerol for the activation of protein kinase C and found that the activation required the presence of an unsaturated fatty acid within the diacylglycerol molecule. Thus, according to the aurthors, 1 ,2-diacylglycerols containing two long-chain saturated fatty acids were less effective than diolein. According to Farooqui et al., Cabot and Jaken, and Lapetina et al., on the other hand, indicated that some saturated diacylglycerols (1 ,2- didecanoylglycerol and 1 -palmitoyl-2-butyrylglycerol) were capable of activating protein kinase C activity. Farooqui et al. continue that Boni and Rando, during a study on the nature of protein kinase C activation by physically defined phospholipid vesicle and diacylglycerol, found that the specificity of protein kinase C activation is directed at the glycerol backbone and the position but not the nature of fatty side chains. According to Farooqui et al., these studies indicated that only 1 ,2-sn-dioIein, but not its 2,3-sn- enantiomer or its 1 ,3-isomer, was capable of activating protein kinase C. Apparently, according to the authors, the acyl ester must satisfy certain balanced physical properties for water/lipid solubility or orientation so that it can partition favorably into a bilayer for an effective access to protein kinase C. Farooqui et al. disclose that diacylglycerol also regulates, amongst others, tyrosine aminotransferase and that the activity of this enzyme is stimulated. See Farooqui, A.A., et al., "Regulation of Protein Kinase C Activity by Various Lipids", Neurochemical Research, Vol. 13, No. 6, pp 499-51 1 , 1988.

It is also known that the key steps in the biochemical pathway of melanogenesis are the hydroxylation of tyrosine to dop (3,4-dihydroxyphenylalanine) and the oxidation of dopa to dopaquinone via the catalytic action of the enzyme tyrosinase. Duggan et al. disclose that the reactions beyond dopaquinone (see for example their Fig. 2 on page 9, in the reference cited at the en of this paragraph) were once believed to be spontaneous but that i has been determined that these reactions are regulated by several biological factors. According to Duggan et al., dopachrome conversion factor (DCF) increases the conversion of dopachrome to 5,6-dihydroxyindole, and 5,6-dihydroxyindole conversion factor (ICF) increases the conversion of 5,6-dihydroxyindole to the quino and subsequently to melanin. According to Duggan et al., the desir for a deep, dark tan has generated the proliferation of cosmetic products claiming to enhance or accelerate the tanning process- e.g., Germaine Monteil's Pre Tan Starter (1981), Estee Lauder's Golden Pre-Tan Accelerator with a Bio-Tan complex (1985), and Plough's Coppertone Natural Tan Accelerator (1986). Duggan et al. further disclose that these products contain tyrosine, tyrosine derivatives, tyrosine/riboflavin complex and/or amino acid blends. According to Duggan et al., tyrosine is used to increase the substrate available for tyrosinase, and tyrosine was complexed with riboflavin in order to accelerate tyrosine's oxidation. See Duggan, M., et al., "Tyrosinase... The Enzyme Behind the Tan", Cosmetics & Toiletries, pp. 97-101 , March 1987.

In the skin, melanin is produced in melanocytes and transferred to keratinocytes. In a test to determine whether this process is influenced by soluble keratinocyte products, cultured human melanocytes and keratinocytes were studied by P.R. Gordon al. According to the study, the dendricity-inducing activity in keratinocyte cultured medium passed through filters with molecular weight exclusions as low as 500 daltons; while growth promoting activity was found in both retentate and ultra filtrate using 10,000, 2,000, and 500 molecular weight exclusion filters. The study discloses that addition of 100 mM 1-oleoyl-2-acetyl glycerol, a diacylglycerol (DAG) analogue, produced 406 ± 84% of control melanin content and 107 ±. 7% of control cell number. According to the authors, this suggests DAG, a known intracellular messenger, may mediate melanogenesis. The authors conclude that the data shows that keratinocytes release soluble stimulators of melanocyte growth, melanogenesis, and dendricity in vitro and suggest -a regulatory role for keratinocyte in epidermal pigmentation. See Gordon, .P.R. et al., "Cultured keratinocytes Release Factors That Increase Melanocyte Growth, Melanization and Dendricity", Journal of Investigative Dermatology, Vol. 90, No. 4, page 564, April 1988.

Wren et al. report their examination of the possibility that activation of melanocytes (MC) by ultraviolet radiation (UVR) is mediated by diacylglycerol. The effects of 1 -oleyl-2-acetyl glycerol (OAG), dioctanoyl glycerol (DOG) and 12-0 tetradecanoyl phorbol 13-acetate (TPA) were compared on the UV-induced responses of cultured human MC (HuMC) and on a Cloudman S91 melanoma cell line. According to the the authors, OAG, known to activate protein kinase C, caused a significant dose-related augmentation of melanogenesis in both human MC and S91 cells: at 100 mM OAG, basal melanin content was increased by 7.2 fold in HuMC and 3.1 fold in S91 ceils, while in UV-irradiated cells, OAG caused increases of 10.2 and 6.1 respectively. The authors also report that DOG, another diacylglycerol that activates kinase C, caused only a 70% increase in basal melanin content and a 2 fold increase in UV-induced melanogenesis in HuMC. Wren et al. also report that TPA, a potent activator of protein - kinase C, had no significant effect on either basal or UV-induced melanin in either cell type. These data suggest, according to Wren et al., that the induced signal activating melanogenesis could be mediated by di- acyl glycerol. Furthermore, they imply, according to the authors, that the signal is transduced via an alternative, protein kinase C- independent pathway.

Consumers are becoming more and more health conscious, and as such there is increasing concern over excessive exposure to solar or artificially produced UV radiation during attempts to obtain a tanner appearance. The production of melani is the body's response to exposure to UV radiation which results i a tanned appearance. A method and a composition for enhancing o increasing melanin production without exposure to UV radiation, with reduced time exposure to UV radiation, can result in a faster darker and safer tan and would be a welcome contribution to the This invention provides just such a contribution.

SUMMARY OF THE INVENTION

It has surprisingly and unexpectedly been discovered that topical applications of Protein Kinase C Activators are sufficiently absorbed through the skin to effect an enhanced, potentiated or increased production of melanin. This is particula surprising, because in vitro enhancement of melanogenesis is not suggestive of in vivo enhancement, particularly when such in vivo use is by topical applications to the skin. Thus, it has been discovered that a Protein Kinase C activator (melanin enhancer), when applied to the skin, penetrates the stratum corneu-m and the epidermis to reach the melanocytes. Without wishing to be bound theory, it is believed that the absorbed Protein Kinase C (hereinafter "PK-C") Activator enhances, potentiates or increases the growth and replication- of tyrosinase and melanosomal protein without exposure to UV radiation by delaying cells in G2 phase of the cell cycle causing increased protein synthesis, particularly tyrosinase. In addition, the growth and replication of melanin precursors --i.e., tyrosinase and melanosomes- is enhanced, potentiated or increased when a PK-C Activator is used in combination with exposure to UV radiation (UVA 320-400 nm and/or UVB 290-320 nm). This enhanced production of melanin precursors (tyrosinase and melanosomes) and ultimately melanin itself results in more melanin being produced than would normally be produced under similar conditions but without the topical use of a PK-C Activator.

Thus, this invention provides a method of enhancing melanin production comprising applying topically to the skin a composition comprising an effective amount of at least one Protein Kinase C Activator. The PK-C Activator is applied in an amount effective to stimulate the enhanced production of melanin.

Generally, the PK-C Activator is combined with a suitable solvent and other optional ingredients.

Another embodiment of this invention provides a composition comprising:

(a) at least one Protein Kinase C Activator present in an amount effective to enhance melanin production when said composition is applied topically to the skin, and

(b) at least one physiologically acceptable solvent for said Activator.

Preferably, the composition will also contain an effective amount of a suitable antioxidant. The composition can optionally contain at least one other ingredient selected from the group consisting of: riboflavin, riboflavin phosphate, a mixture of riboflavin and riboflavin phosphate, DOPA phosphates, sunscreening agents, emollients, emulsifiers, solvents for sunscreening agents, waxes, thickeners, film formers, humectants, antioxidants, preservatives, surfactants, perfumes, biological additives, buffering agents, chelating agents, emulsion stabilizers, opacifying agents, pH adjusters, propellants, and coloring agents.

DETAILED DESCRIPTION OF THE INVENTION

The PK-C Activators useful in this invention are those Activators which are physiologically compatible with the skin, are reae.ily absorbable through or into the skin, and penetrate through the stratum corneum and the epidermis to reach the melanocytes. The PK-C Activators may be used individually or in combination. Suitable PK-C Activators are those physiologically acceptable substances which activate protein kinase C by their direct action, or are substances which are metabolized to other substances which activate protein kinase C, or are substances which act upon other substances to produce a resulitng substance that activates protein kinase C and may include substances selected from the group consisting of: diacylglycerols; triacylglycerols; lipopoiysaccharides; unsaturated free fatty acids; short chain saturated free fatty acids; glycophospholipids; enzymes which hydrolyze glycophospholipids (phosphoglycerides) to diacylglycerols such as Phospholipase C which hydrolyzes the phosphodiester bond linking the phosphorylated inositol unit to the acylated glycerol moiety to form diacylglycerol in the phosphoinositide cascade; and naturally occurring substances such as bryostatins which are naturally occurring macrocylic lactones found in bryozoa. The acyl groups of the diacylglycerols and triacylglycerols can be unsaturated, saturated or a combination of unsaturated and saturated. Each acyl chain (group) contains at least 1 carbon atom (including the carbonyl carbon) and usually contains from about 1 to about 30 carbon atoms (including the carbonyl carbon) with about 2 to about 24 carbon atoms being preferred and about 6 to about 20 carbon atoms being most preferred. Normally, the acyl group is derived from a naturally occurring fatty acid and the fatty acid usually contains an even number of carbon atoms and is unbranched. Although 1 ,2-diacyl- rac-glycerols are useful, the diacylglycerols are preferably 1 ,2- diacylglycerols, and most preferably 1 ,2-diacyl-sn-gIycols.

Representative saturated free fatty acids (fatty acids) from which the acyl groups may be derived from include, but are not limited to: methanoic (formic); ethanoic (acetic); propanoic (propionic); butanoic (butyric); pentanoic (valeric); hexanoic (caproic); heptanoic (enanthic); octanoic (caprylic); nonanoic (pelargonic); decanoic (capric); undecanoic (undecylic); dodecanoic (lauric); tridecanoic (tridecylic); tetradecanoic (myristic); pentadecanoic (pentadecylic); hexadecanoic (palmitic); heptadecanoic (margaric); octadecanoic (stearic); nonadecanoic (nonadecylic); eicosanoic (arachidic); heneicosanoic; docosanoic (behenic); trϊcosanoic; tetracosanoic; pentacosanoic; hexacosanoic (cerotic); heptacosanoic; octacosanoic (montanic); nonacosanoic; triacontanoic (melissic); and the like. Preferred saturated acyl groups are derived from fatty acids selected from the group consisting of: acetic, hexanoic, octanoic, decanoic, hexadecanoic, octadecanoic, and eicosanoic. Most preferred saturated fatty acids are selected from the group consisting of: acetic, hexanoic, octanoic and octadecanoic. Representative unsaturated free fatty acids (fatty acids) from which the acyl groups may be derived from include, but are not limited to:

1. 10-undecenoic (10-undecylenic);

2. cis-9-tetradecenoic (myristoleic);

3. cis-9-hexadecenoic (palmitoleic);

4. trans-9-hexadecenoic (palmitelaidic) ;

5. cis-6-octadecenoic (petroselinic); 6. trans-6-octadecenoic (petroselaidic);

7. cis-9-ootadecenoic (oleic);

8. trans-9-octadecenoic (elaidic);

9. cis-1 1 -octadecenoic (cis-vaccenic);

10. trans-11 -octadecenoic (trans-vaccenic); 1 1. cis-12 hydroxy-9-octadecenoic (ricinoleic) ;

12. trans-12-hydroxy-9-octadecenoic (ricinelaidic);

13. cis-9,12-octadecadienoic (linoleic) ;

14. trans-9,12-octadecadienoic (linolelaidic);

15. cis-6,9,12-octadecatrienoic (g-linolenic) ; 16. cis-9,12,15-octadecatrienoic (linolenic);

17. cis-6,9,12,15-octadecatetraenoic;

18. cis-1 1 -eicosenoic (gondoic);

19. cis-13-eicosenoic;

20. cis-1 1 ,14-eicosadienoic; 21. cis-8,1 1 ,14-eicosatrienoic;

22. cis-1 1 ,14,17-eicosatrienoic;

23. cis-5,8,1 1 ,14-eicosatetraenoic (arachidonic) ;

24. cis-5,8,1 1 ,14,17-eicosapentaenoic;

25. cis-13-docosenic (erucic); 26. trans-13-docosenoic (brassidic);

27. cis-13,16-docosadienoic;

28. cis-13,16, 1 9-docosatrienoic; 29. cis-7,10,13,16-docosatrienoic;

30. cis-4,7,10,13,16,19-docosahexanoic;

31. cis-15-tetracosenoic (nervonic); and the like.

Preferred unsaturated fatty acids are selected from the group consisting of: cis-9-octadecenoic; and cis-5,8,11,14- eicosatetraenoic.

Representative diacylglycerols include, but are not limited to: 1. diarachidin (dieicosanoyl-glycerol, reported to be approximately 50% 1,3- and 50% 1,2-isomer);

2. 1,3-diarachidin (1,3-dieicosanoylglycerol);

3. dicaprin (didecanoylglycerol, reported to be 50% 1,3- and 50% 1,2-isomer); 4. 1,3-dicaprin (1,3-didecanoylglycerol);

5. dicaproin (dihexanoylglycerol, reported to be 50% 1,3- and 50% 1,2-isomers);

6. dicaprylin (1,3-dioctanoylglycerol);

7. 1,2-didecanoyl-rac-glycerol (1,2-dicaprin); 8. 1,3-di-cis-11-eicosenoin;

9. 1,3-dielaidin (1 ,3-di-[(trans)-9- octadecenoyljglycerol);

10. 1,3-dierucin (1,3-di-[(cis)-13-docosenoylJ-rac- glycerol); 11. 1,2-dihexanoyl-sn-glycerol;

12. dilaurin (didodecanoylglycerol, reported to be approximately 50% 1,3- and 50% 1,2-isomer);

13. 1,3-dilaurin (1,3-didodecanoylglycerol);

14. 1,2-dilauroyl-rac-glycerol (1,2-didodecanoyl-rac- glycerol);

15. dilinolein (1,3-di-[(cis,cis)-9,12- octadecadienoyl]-rac-glycerol); 16. dilinolenin (di-[(cis,cis,cis)-9, 12,15- octadecatrienoyl]glycerol);

17. dimyristin (ditetradecanoylglycerol, reported to be approximately 50% 1,3- and 50% 1,2-isomer); 18. 1,3-dimyristin (1,3-ditetradecanoylglycerol);

19. 1 ,2-dimyristoyl-rac-glycerol (1,2- ditetradecanoyl-rac-glycerol);

20. 1 ,2-dioctanoyl-rac-glycerol (1,2-dicapryloyl-rac- glycerol); 21. 1 ,2-dioctanoyl-sn-glycerol (1,2-dicapryloyl-sn- glycerol);

22. diolein (di-[(cis)-9-octc<decenoyl]glycerol, reported to be approximately 85% 1,3- and 15% 1,2-isomer);

23. 1,3-diolein (1,3-di-[(cis)-9-octadecenoyl); 24. 1,2-dioleoyl-rac-glycernl (1,2-di[(cis)-9- octadecenoylj-rac-glycerol);

25. 1,2-dioleoyl-sn-glycerol (1 ,2-di[(cis)-9- octadecenoyl]-sn-glycerol);

26. dipalmitin (dihexadecanoylglycerol, renorted to be approximately 50% 1,2- and 50% 1,3-isomer);

27. 1,3-dipalmitin (1,3-dihexadecanoylglycerol);

28. 1,3-dipalmitolein (1,3-di-[(cis)-9- hexadecenoyljglycerol);

29. 1,2-dipalmitoyl-sn-glycerc! (1,2-dihexadecanoyl- sn-glycerol);

30. 1 ,2-dipalmitoyl-rac-glycerol (1,2- dihexadecanoyl-rac-glycerol);

31. 1,3-dipentadecanoin (1,3- dipentadecanoylglycerol); 32. distearin (dioctadecanoylglycerol, reported to be approximately 50% 1,3- and 50% 1,2-isomer);

33. 1,3-distearin (1,3-dioctadecanoylglycerol); 34. 1 ,2-distearoyl-rac-glycerol (1 ,2-dioctadecanoyl- rac-glycerol) ;

35. 1 -oleoyl-2-acetyl-rac-glycerol (1 -[(cis)-9- octadecenoyl]-2-acetyl-rac-glycerol); 36. 1 -oleoyl-2-acetyl-sn-glycerol (1 -[(cis)-9- octadecenoyl]-2-acetyl-sn-glycerol);

37. 1 -palmitoyl-3-stearoyl-rac-glycerol (1 - hexadecanoyl-3-octadecanoyl-rac-glycerol);

38. 1 -stearoyl-2-arachidonoyl-sn-glycerol (1 - octadecanoyl-2-[(cis,cis,cis,cis)-5,8,1 1 ,14-eicosatetraenoyl]-sn- glycerol);

39. 1 -acetyl-2-oleoylglycerol (1 -ethanoyl-2-[(cis)- 9-octadecenoylglycerol) ;

40. 1 -stearoyl-2-oleoylglycerol (1 -octadecanoyl-2- [(cis)-9-octadecenoylglycerol; and the like.

Preferably the diacylglycerol is selected from the group consisting of:

1. 1 ,2-dihexanoyl-sn-glycerol; 2. 1 ,2-dioctanoyl-rac-glycerol;

3. 1 ,2-dioctanoyl-sn-glycerol ;

4. 1 -oleoyl-2-acetyl-rac-glycerol;

5. 1 -oleoyl-2-acetyl-sn-glycerol;

6. 1 -stearoyl-2-arachidonoyl-sn-glycerol; ^* 7. 1 ,2-didecanoyl-rac-glycerol;

8. 1 -acetyl-2-oleoyl glycerol;

9. 1 -stearoyl-2-oleoyl glycerol;

10. 1 ,2-dipaImitoyl-rac-glycerol;

11. 1 ,2-dipalmitoyl-sn-glycerol; 12. 1 ,2-distearoyl-rac-glycerol;

13. 1 ,2-dioleoyl-rac-glycerol;

14. 1 ,2-dioleoyl-sn-glycerol;

Most preferably the diacylglycerol is selected from the group consisting of: 1 ,2-dihexanoyl-sn-glycerol; 1 ,2-dioctanoyl- rac-glycerol; 1 ,2-dioctanoyl-sn-glycerol; 1 -oleoyl-2-acetyl-rac- glycerol; 1 -oleoyl-2-acetyl-sn-glycerol, or 1 -stearoyl-2- arachidonoyl-sn-glycerol. Most preferably 1 ,2-dioctanoyl- ac- glycerol or 1 ,2-dioctanoyl-sn-glycerol is used.

Diacylglycerols are available commercially from, for example: (1) Sigma Chemical Company, St. Louis, MO. --see Sigma's 1989 catalogue of Biochemicals Organic Compounds for Research and Diagnostic Reagents; (2) Serdary Research Laboratories, Port Huron, Ml; (3) Molecular Probes Inc., Junction City, OR; and (4) Avanti Polar Lipids, Birmingham, AL.

Diacylgycerols may also be prepared in accordance with procedures well known in the art, for example see: (1) Gunstone et al., editors, The Lipid Handbook pp. 295, et seq., ©1986; (2) Ebeling et al., Proc. Natl. Acad. Sci. USA, Vol. 82, pp 815-819, at page 816, February 1985; and (3) Ganong et al., Proc. Natl. Acad. Sci. USA, Vol. 83, pp. 1184-1188, March 1986.

Representative triacylglycerols may include but are not limited to:

1. 1 ,2-dilauroyl-3-myristoyl-rac-glycerol (1 ,2- didodencanoyl-3-tetradecanoyl-rac-glycerol) ; 2. 1 ,2-dimyristoyl-3-lauroyl-rac-glycerol (1 ,2- ditetradecanoyl-3-dodecanoyl-rac-glycerol);

3. 1 ,2-dimyristoyl-3-oleoyl-rac-glycerol (1 ,2- ditetradecanoyl-3-[(cis)-9-octadecenoyl]-rac-glycerol) ; 4. 1 ,2-dimyristoyl-3-palmitoyl-rac-glycerol

(ditetradecanoyl-3-hexadecanoyl-rac-glycerol);

5. 1 ,2-dioleoyl-3-palmitoyl-rac-glycerol (1 ,2-di- [(cis)-9-octadecenoyl]-3-hexadecanoyl-rac-glycerol) ;

6. 1 ,3-dioleoyl-2-palmitoy!glycerol (1 ,3-di-[(cis)- 9-octadecenoyl]-2-hexadecanoylglycerol);

7. 1 ,2-dioleoyl-3-(pyren-1 -yl)decanoyl-rac- glycerol); ^•

8. 1 ,2-dioleoyl-3-stearoyl-rac-glyceroI (1 ,2-di- [(cis)-9-octadecenoyl]-3-octadecanoyl-rac-glycerol) ; 9. 1 ,3-dioleoyl-2-stearoylglycerol (1 ,3-di-[(cis)-9- octadecenoyl]-2-octadecanoylglycerol;

10. 1 ,2-dipalmitoyl-3-myristoyl-rac-glycerol (1 ,2- dihexadecanoyl-3-tetradecanoyl-rac-glycerol);

11 . 1 ,2-dipalmitoyl-3-oleoyl-rac-glycerol (1 ,2- dihexadecanoyl-3-[(cis)-9-octadecenoyl]-rac-glycerol) ;

12. 1 ,3-dipalmitoyl-2-oleoylglycerol (1 ,3- dihexadecanoyl-2[(cis)-9-octadecenoyl]glycerol);

13. 1 ,2-distearoyl-3-myristoyl-rac-glycerol (1 ,2- dioctadecanoyl-3-tetradecanoyl-rac-glycerol); 14. 1 ,2-distearoyI-3-oleoyl-rac-glycerol (1 ,2- dioctadecanoyl-3-[(cis)-9-octadecenoyl]-rac-glycerol) ;

15. 1 ,3-distearoyl-2-oleoylglycerol (1 ,3- octadecanoyl-2-[(cis)-9-octadecanoyl]glycerol);

16. 1 ,2-distearoyl-3-pa!mitoyl-rac-glycerol (1 ,2- dioctadecanoyl-3-hexadecanoyl-rac-glycerol); 17. 1 -palmitoyl-2-oleoyl-3-stearoyl-rac-glycerol (1 - hexadecanoyl-2-[(cis)-9-octadecenoyl]-3-octadecanoyl-rac- glycerol);

18. triacetin (1 ,2,3-triacetylglycerol; glyceryl triacetate) ;

19. triarachidin (1 ,2,3-trieicosanoylglycerol);

20. triarachidonin (1 ,2,3-tri-[(cis,cis,cis,cis)- 5,8,1 1 ,14-eicosatetraenoyl]glycerol);

21 . tribehenin (1 ,2,3-tridocosanoylglycerol); 22. tributyrin (1 ,2,3-tributyrylglycerol; glyceryl tributyrate) ;

23. tricaprin (1 ,2,3-tridecanoylglycerol) ;

24. tricaproin (1 ,2,3-trihexanoylglycerol; trihexanoin); 25. tricaprylin (1 ,2,3-trioctanoylglycerol; glyceryl tricaprylate);

26. tri-1 1 -eicosenoin (1 ,2,3-tri-[(cis)-1 1 - eicosenoylj-glycerol);

27. trielaidin (1 ,2,3-tri-[(trans)-9- octadecenoyljglycerol);

28. trierucin (1 ,2,3-tri-[(cis)-13- docosenoyI]glycerol);

29. triheptadecanoin (1 ,2,3-triheptadecanoylglycerol);

30. trilaurin (1 ,2,3-tridodecanoylglycerol); 31. trilinolelaidin (1 ,2,3-tri-[(trans,trans)-9,12- octadecadienoyljglycerol);

32. trilinolein (1 ,2,3-tri-[(cis,cis)-9,12- octadecadienoyljglycerol) ;

33. trilinolenin (1 ,2,3-tri-[(cis,cis,cls)-9,12,15- octadecatrienoylj-glycerol) ;

34. trimyristin (1 ,2,3-tritetradecanoylglycerol); 35. trimyristolein (1 ,2,3-tri-[(cis)-9-tetradecenoyl]- glycerol) ;

36. trinervonin (1 ,2,3-tri-[(cis)-15- tetracosenoyljglycerol) ; 37. trinonadecanoin (1 ,2,3-trinonadecanoylglycerol);

38. trinonanoin (1 ,2,3-trinonanoylglycerol; pelargonin);

39. triolein (1 ,2,3-tri-[(cis)-9-octadecenoyl]glycerol ; glyceryl trioleate); 40. tripalmitin (1 ,2,3-trihexadecanoylglycerol);

41. tripalmitolein (1 ,2,3-tri-[(cis)-9-hexadecenoyl]- glycerol) ; ^•

42. tripentadecanoin (1 ,2,3-tripentadecanoylglycerol);

43. tripetroselinin (1 ,2,3-tri-[(cis)-6-octadecenoylj- glycerol);

44. tristearin (1 ,2,3-trioctadecanoylglycerol);

45. tritridecanoin (1 ,2,3-tritridecanoylglycerol);

and the like. These triacylglycerols are commercially available from Sigma Chemical Company (same address and catalogue as cited above). Triacylglycerols may also be prepared in accordance with procedures well known in the art, for example see Gunstone et al., editors, The Lipid Handbook, p. 295 et seq., ©1986.

Lipopolysaccharides (LPS) may also be useful in this invention as PK-C Activators. The active lipid moiety. of LPS of Gram-negative bacteria is diacylglucosamine 1 -phosphate. Thus, either a diacylglucosamine 1 -phosphate or the LPS containing it may be used. The acyl groups of the diacylglucosamine 1- phosphates from LPS are usually from predominantly Ci 4 to Ci 8 fatty acids which may be saturated or monosaturated, but not polyunsaturated. On LPS and bacterial fatty acids see, for example, Davis et al., editors, Microbiology. Third Edition, pp 82 to 91 , ©1980, the disclosure of which is incorporated herein by reference thereto.

Representative examples of bacteria from which LPS can be derived from for use in this invention include, but are not limited to: Escherichia coli (E. coli), Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella abortus equi, Salmonella enteritidis, Salmonella minnesota, Salmonella typhimurium, Salmonella typhosa, Serratia marcescens, Shigella flexneri, Vibrio cholerae, and the like. Bacterial Lipid A and Lipid X may also prove useful. Lipid A aind Lipid X are well known to those skilled in the art. See for example: (1) Wightman et al., The Journal of Biological Chemistry. Vol. 259, No. 16, pp 10048-10052, August 25, 1984; and (2) Davis et al., editors, Microbiology. Third Edition, pp. 85, 87, and 654-655, ©1980; the disclosures of each being incorporated herein by reference thereto. Lipid A is commercially available from, for example, Sigma Chemical Company. Lipid X is available from Lipidex, Inc., Middleton, Wl.

LPS are available commercially, for example, form Sigma Chemical Co. (already cited above). Examples of LPS available comercially include those derived from: E. coli Serotype 026:B6; E. coli Serotype 055:B5; E. coli Serotype 0111 :B4; E. coli Serotype 0127:B8; E. coli Serotype 01 8:B12; E. coli EH-100 (Ra mutant); E. coli F-583 (Rd mutant); E. coli Strain J5 (Re mutant); E. coli K235, Klebsiella pneumonia;, Pseudomonas aeruginosa; Pseudomonas aeruginosa Serotype 10 (Habs); Salmonella abortus equi, Salmonella enteritidis, Salmonella Minnesota, Salmonella Minnesota Strain R5; Salmonella Minnesota Strain R7 (Rd mutant); Salmonella Minnesota Strain Re 595 (Re mutant); Salmonella typhimurium; Salmonella typhimurium Strain TV119 (Ra mutant); Salmonella typhimurium Strain SL684 (Re mutant); Salmonella typhimurium Strain SL1181 (Re mutant); Salmonella typhosa, Serratia marcescens; Shigella flexneri Serotype 1A; Shigella flexneri (Re mutant); and Vibrio cholerae Serotype INABA 569B. LPS may be derived from bacteria by techniques well known to those skilled in the art. For example, lyophilized powders are available as phenol, trichloroacetic acid (TCA), butanol or phenol-chloroform-petroleum ether extracts. Such procedures are referenced in Sigma Chemical Company's 1989 Biochemicals Organic Compounds catalogue (cited above) as: Westphal et al., Methods in Carbohydrate Chem., 5., 83 (1965) for a phenol extraction procedure; Staub, Methods in Carbohydrate Chem., 5., 92 (1965) for a TCA extraction procedure; Lieve et al., Methods in Enzymology, XXVIIIb. 254 (1972) for a butanol extraction procedure; and Galanos et al., Eur.. J. Biochem., 2., 245 (1969) for a phenol-chloroform- petroleum ether extraction. Unsaturated free fatty acids (fatty acids) may also be useful in this invention as PK-C Activators. It is believed that unsaturated free fatty acids having 1 to about 4 double bonds and ^■ about 14 to about 20 carbon atoms are preferred PK-C Activators. Cis- and trans-unsaturated free fatty acids are suitable with the proviso that trans-elaidic acid may not be as useful as other unsaturated free fatty acids. Although chain lengths of 14-20 carbon atoms are preferred other chain lengths (less than 14 or more than 20) may also prove useful. Suitable unsaturated free fatty acids may be selected from amongst those unsaturated fatty ^• acids already described above for the acyl groups of the diacylglycerols and triacylglycerols. Preferred unsaturated free fatty acids include linoleic acid, arachidonic acid and oleic acid.

Short chain saturated free fatty acids (fatty acids) may also prove useful. Suitable saturated free fatty acids may be selected from amongst those saturated fatty acids, having 4 to 10 carbon atoms, described above for the acyl groups of the diacylglycerols and the triacylglycerols. Saturated fatty acids having more than 10 carbon atoms --e.g., 11 -20- may also prove useful. Thus, lauric, myristic, palmitic, stearic, and arachidic may be suitable.

Another group of compounds which may be useful in this invention as PK-C Activators for enhancing melanin production are glycerophospholipids (phosphoglycerides). Phosphoglycerides consist of a glycerol background, two acyl groups derived from fatty acids (usually bound to the C-1 and C-2 glycerol carbons) and a phosphorylated alcohol. The major phosphoglycerides are derivatives of phosphatidate (diacylglycerol 3-phosphate). The phosphate group of phosphatidate becomes esterified to the hydroxyl group of one of several alcohols. Examples of alcohols include serine, threonine, ethanolamine, choline, glycerol, inositol, and the like. The disclosure above pertaining to the acyl groups of the di- and triacylglycerols pertain equally as well to the acyl groups of the phosphoglycerides.

Representative examples of phosphoglycerides include, but are not limited to:

1 . L-α-phosphatidylcholine (L-α-lecithin) such as that obtained from bovine brain, bovine heart, bovine liver, egg yolk (diced, fresh, frozen or fresh frozen), turkey egg yolk (fresh), and soybean;

2. L-α-phosphatidylcholine, β-acetyl-γ-O-alkyl (1 -0- alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine); 3. D-α-phosphatidylcholine, β-acetyl-γ-O-hexadecyl;

4. DL-α-phosphatidylcholine, β-acetyl-γ-O- hexadecyl;

5. L-α-phosphatidylcholine, β-acetyl-γ- O-hexadecyl;

6. L-α-phosphatidylcholine, β-acetyl-γ- 0-(octadec- 9-cis-enyl) ;

7. L-α-phosphatidylcholine, β-O-acetyl-γ-O- octadecyl; 8. L-α-phosphatidylcholine, β-acetyl-γ-oleoyl (1 - [(cis)-9-octadecenoyl]-2-acetyl-sn-glycero-3-phosphocholine);

9. L-α-phosphatidylcholine, β-arachidonoyl, γ- stearoyl (1 -octadecanoyl-2-[(cis,cis,cis,cis)-5,8,1 1 ,14- eicosatetraenoyl]-sn-glycero-3-phosphocholine);

10. L-α-phosphatidylcholine, diarachidoyl;

11 . L-α-phosphatidylcholine, dibehenoyl;

12. L-α-phosphatidylcholine, dibutyroyl;

13. L-α-phosphatidylcholine, dicaproyl; 14. L-α-phosphatidylcholine, didecanoyl;

15. L-α-phosphatidylcholine, dielaidoyl; ^• 16. L-α-phosphatidylcholine, diheptadecanoyl;

17. L-α-phosphatidylcholine, diheptanoyl;

18. DL-α-phosphatidylcholine, di-O-hexadecyl (1 ,2- di-O-hexadecyl-rac-glycero-3-phosphocholine);

19. DL-α-phosphatidylcholine, dilauroyl (1 ,2- didodecanoyl-rac-glycero-3-phosphocholine);

20. L-α-phosphatidylcholine, dilauroyl;

21 . L-α-phosphatidylcholine, dilinoleoyl; 22. L-α-phosphatidycholine, dimyristoyl;

23. L-α-phosphatidylcholine, dinonanoyl (1 ,2- dinonanoyl-sn-glycero-3-phosphocholine);

24. L-α-phosphatidylcholine, dioctanoyl (1 ,2- dioctanoyl-sn-glycero-3-phosphocholine); 25. DL-α-phosphatidylcholine, dioleoyl;

26. L-α-phosphatidylcholine, dioleoyl;

27. D-α-phosphatidylcholine, dipalmitoyl (2,3- dihexadecanoyl-sn-glycero-1 -phosphocholine);

28. DL-α-phosphatidylcholine, dipalmitoyl; 29. L-α-phosphatidylcholine, dipalmitoyl;

30. L-α-phosphatidylcholine, dipentadecanoyl (1 ,2- dipentadecanoyl-sn-glycero-3-phosphocholine); 31 . L-α-phosphatidylcholine, distearoyl;

32. L-α-phosphatidylcholine, diundecanoyl (1 ,2- diundecanoyl-sn-glycero-3-phosphocholine);

33. L-α-phosphatidylcholine, divaleroyl; 34. L-α-phosphatidylcholine, β-elaidoyl-γ-palmitoyl ;

35. L-α-phosphatidylcholine, β-linoleoyl-γ-palmitoyl ;

36. DL-α-phosphatidylcholine, β-O-methyl-γ-O- hexadecyl (1 -0-Hexadecyl-2-0-methyl-rac-glycero-3- phosphocholine); 37. L-α-phosphatidylcholine, β-O-methyl-γ-O- octadecyl;

38. L-α-phosphatidylcholine, β-(NBD-aminohexanoyl)- γ-palmitoyl (1 -hexadecanoyl-1 -[(N-(7-nitrobenz-2-oxa-1 ,3-diazol-

4-yl)-aminohθxanoyl]-sn-glycero-3-phosphocholine); 39. DL-α-phosphatidylcholine, β-oleoyl-γ-O-hexadecyl

(1 -0-hexadecyI-2-[(cis)-9-octadecenoyl]-rac-glycero-3- phosphocholine);

40. L-α-phosphatidylcholine, β-oleoyl-γ-palmitoyl;

41 . L-α-phosphatidylcholine, β-oleoyl-γ-stearoyl; 42. DL-α-phosphatidylcholine, β-palmitoyl-γ-O- hexadecyl (1 -0-hexadecyl-2-hexadecanoyl-rac-glycero-3- phosphocholine);

43. L-α-phosphatidylcholine, β-palmitoyl-γ-oleoyl;

44. L-α-phosphatidylcholine, β-palmitoyl-γ-(pyren-1 - yl)-hexanoyl;

45. L-α-phosphatidylcholine, β-(pyren-1 -yl)decanoyl- γ-palmitoyl;

46. L-α-phosphatidylcholine, β-(pyren-1 -yl)hexanoyl- γ-palmitoyl; 47. L-α-phosphatidylcholine, β-stearoyl-γ-oleoyl;

48. DL-α-phosphatidyl-N,N-dimethylethanolamine, dipalmitoyl; - 24 -

49. L-α-phosphatidyl-N,N-dimethylethanolamine, dipalmitoyl;

50. L-α-phosphatidylethanolamine (L-α-cephalin), such as that obtained from bovine brain, sheep brain, egg yolk, soybean, Escherichia coli, dog brain, bovine liver, or porcine liver;

51. L-α-phosphatidylethanolamine, diheptadecanoyl (1 ,2-diheptadecanoyl-sn-glycero-3-phosphoethanolamine) ;

52. L-α-phosphatidylethanolamine, dilauroyl (1 ,2- didodecanoyl-sn-glycero-3-phosphoethanolamine); 53. L-α-phosphatidylethanolamine, dimyristoyl (1 ,2- ditetradecanoyl-sn-glycero-3-phosphoethanolamine) ;

54. phosphatidylethanolamine, dinitrophenyl;

55. L-α-phosphatidylethanolamine, dioleoyl (1 ,2- di[(cis)-9-octa-decenoyl]-sn-glycero-3-phosphoethanolamine) ; 56. DL-α-phosphatidylethanolamine, dipalmitoyl;

57. L-α-phosphatidylethanolamine, dipalmitoyl;

58. L-α-phosphatidylethanolamine, dipalmitoyl-N- dansyl (1 ,2-dihexadecanoyl-sn-glycero-3-phospho-[N- dansyljethanolamine); 59. L-α-phosphatidylethanolamine, dipalmitoyl, N- fluorescein isothiocyanyl (1 ,2-dihexadecanoyl-sn-glycero-3- phospho-[N-fluorescein isothiocyanyljethanolamine) sodium salt;

60. L-α-phosphatidylethanolamine, dipalmitoyl, N-NBD (1 ,2-dihexadecanoyl-sn-glycero-3-phospho-[N-(4-nitrobenzo-2- oxa-1 ,3-diazole)Jethanoiamine);

61. L-α-phosphatidylethanolamine, distearoyl (1 ,2- dioctadecanoyl-sn-glycero-3-phosphoethanolamine);

62. L-α-phosphatidylethanolamine, β-linoleoyl-γ- palmitoyl (1 -hexadecanoyl-2-[(cis,cis)-9,12,octadecadienoyl]-sn- glycero-3-phosphoethanolamine);

63. L-α-phosphatidylethanolamine, β-oleoyl-γ- palmitoyl; 64. phosphatidylethanolamine, plasmalogen;

65. phosphatidylethanolamine, N-trinitrophenyl;

66. L-α-phosphatidyl-DL-glycerol (1 -[3-sn- phosphatidyl]-rac-glyceroI) [prepared by reaction of cabbage phospholipase D with egg yolk L-α-phosphatidylcholine in the presence of glycerol], including the ammonium salt from egg yolk lecithin and the sodium salt from egg yolk lecithin;.

67. L-α-phosphatidyl-DL-glycerol, dimyristoyl (1 ,2- ditetradecanoyl-sn-glycero-3-[phospho-rac-(1 -glycerol)]), including the ammonium and sodium salts;

68. L-α-phosphatidyl-DL-glycerol, dioleoyl (1 ,2- di[(cis)-9-octadecenoyl]-sn-glycero-3-[phospho-rac-(1 -glycerol)]) , ammonium salt;

69. DL-α-phosphatidyl-DL-glycerol, dipalmitoyl (1 ,2- dipalmitoyl-rac-glycero-3-[phospho-rac-(1 -glycerol)]), including the ammonium salt;

70. L-α-phosphatidyl-DL-glycerol, dipalmitoyl (1 ,2- dihexadecanoyl-sn-glycero-3-[phospho-rac-(1 -glycerol)]), including the ammonium and sodium salts; 71 . L-α-phosphatidyl-DL-glycerol, distearoyl (1 ,2- distearoyl-sn-glycero-3-[phospho-rac-(1 -glycerol)]) ammonium salt;

72. L-α-phosphatidylinositol, e.g. from soybean (including the ammonium and sodium salts), and from bovine liver (ammonium salt), as well as TYPE 1 : Folch Fraction 1 from bovine brain reported to contain 10-20% phosphatidyl inositides, 50-60% phosphatidyl serine as well as several other brain lipids; ^'

73. L-α-phosphatidylinositol 4,5-diphosphate (triphosphoinositide) sodium salt from bovine brain; 74. L-α-phosphatidylinositol 4-monophosphate

(diphosphoinositide) sodium salt from bovine brain; 75. phosphoinositides, sodium salt, from bovine brain, Extract Type 1 , reported to contain approximately 15-20% phosphatidylinositol 4-monophosphate and phosphatidylinositol 4,5-biphosphate with the remainder being a mixture of phosphatidylinositol and phosphatidylserine;

76. L-α-phosphatidyl-N-monomethylethanolamine, dipalmitoyl;

77. L-α-phosphatidyl(N-palmitoyl)ethanoIamine, dipalmitoyl (1 ,2-dihexadecanoyl-sn-glycero-3-phospho-[N- hexadecanoyl]ethanolamine) ammonium salt;

. 78. L-α-phosphatidyl-L-serine, e.g., from bovine brain (including the sodium salt), as well as TYPE III: Folch Fraction III from bovine brain reported to contain 80-85% phosphatidylserine with the balance being other brain lipids; 79. L-α-phosphatidylserine, dansyl; and

80. DL-α-phosphatidyl-L-serine, dipalmitoyl.

Although the liquid PK-C Activators may be applied neat to the skin, it is generally more convenient to form a composition by combining, such as by mixing, blending or dissolving, the PK-C Activators with a suitable solvent. In general the PK-C Activator in the composition is in a concentration which is effective to provide the desired level of activity. Usually the PK-C Activator is present in an amount of about 0.01% to about 20% by weight of the ^' total composition with about 0.05% to about 10% being preferred and about 0.05% to about .1.0% being most preferred. Combinations of PK-C Activators may be used such that their total amount is within these specified ranges.

Generally, the PK-C Activator composition is applied in a sufficient amount to uniformly coat the skin. Usually the composition is applied in an amount sufficient to provide about 0.01 to about 120 micromoles of PK-C Activator to an area of skin about 10 to about 12 cm² with about 2 to about 25 micromoles of PK-C Activator being preferred and about 1 to about 10 micromoles being most preferred. Normally, the PK-C Activator is applied at least 1 to about 6 times with about 1 to about 3 times being preferred over a time period of about 24 hours.

Suitable solvents are those which effectively dissolve or disperse the PK-C Activator, or form a stable emulsion therewith, and are inert to the Activator and physiologically acceptable to the skin. Mixtures of solvents may also be used. The solvent may conveniently be a solvent for sunscreening agents. Those skilled in the art will appreciate that the solvents are used in amounts which will provide the desired concentration of PK-C Activator and other ingredients in the composition. Thus, an amount of solvent can be used which would bring the total amount of all ingredients in the composition to 100% by weight.

Suitable solvents may be selected from amongst those solvents well known to those skilled in the art for their use in the cosmetics industry. Examples include, but are not limted to: liposomes; ketones such as acetone and the like; alcohols such as benzyl alcohol, ethanol, t-butyl alcohol, cetyl alcohol, glycol

(HOCH2CH2OH), isopropyl alcohol, propylene glycol, SD alcohol 23- A, SD alcohol 39-C, SD alcohol 40, SD alcohol 40-B and the like; Fats and oils such as avocado oil, cocoa butter, coconut oil, corn oil, hydrogenated coconut oil, hydrogenated cottonseed oil, hydrogenated vegetable oil, lanolin oil, mink oil, palm oil, peanut oil, safflower oil, soybean oil, sunflower seed oil, sweet almond oil, vegetable oil (expressed oil of vegetable origin consisting primarily of triglycerides of fatty acids), walnut oil, wheat germ oil and the like; hydrocarbons such as mineral oil and the like; alkoxylated alcohols or polymeric ethers such as PEG-8, PEG-14M and the like; lanolin and lanolin derivatives such as hydrogenated lanolin and the like; glyceryl esters and derivatives such as hydrogenated palm kernel oil and the like; esters such as isopropyl myristate, isopropyl palmitate and the like; water; and the like. Addition solvents which may be used can be found on Nikitakis, Editor, CTFA Cosmetic Ingredient Handbook. First Edition, published by the Cosmetic, Toiletry and Fragrance Association, Inc., 1110 Vermont Avenue, N.W., Washington, D.C., ©1988, the disclosure of which is incorporated herein by reference thereto. In particular, see the section "Solvents" on pp. 85-86.

Those skilled in the art will appreciate that, in general, the PK-C Activators are lipophilic. Therefore, if it is desirable to use water as a solvent it may be desirable to add components to the water to improve the solubility of the PK-C Activator in the water. For example, solvents such as alcohols and ketones, discussed above, which are water miscible may be added to improve the solubility of the PK-C Activator.

Liposomes (lipid vesicles) may also prove useful as a solvent for the PK-C Activators, or as a means of encapsulating the PK-C Activators, or as a means of complexing with the PK-C Activators. Liposomes are aqueous compartments enclosed by a lipid bilayer. They are produced by techniques well known to those skilled in the art. For example, liposomes can be produced by suspending a suitable lipid, such as phosphatidyl choline, in an aqueous medium. This mixture is then sonicated to give a dispersion of closed vesicles that are quite uniform in size. See, for example, Stryer, Biochemistry. Third Edition, pp. 290-292,

©1988, the disclosure of which is incorporated herein by reference thereto.

Among the useful liposomes are stratum corneum lipid liposomes formed from epidermal ceramides, cholesterol, palmitic acid and cholesterol sulfate as described in Abraham et al., The Journal of Investigative Dermatology, 9J 259-262 (1988). Many lipids are believed suitable for use in making the liposomes, many of which are commercially available, e.g. Liposome Kit is available from Sigma Chemical Company, St. Louis, Missouri under catalog number L-4262. Liposome Kit L-4262 contains L- alpha-phosphatidylcholine (egg yolk), dicetyl phosphate and cholesterol. It is a negatively charged lipsome mixture, another suitable negatively charged liposome mixture available from Sigma Chemcial Company is L-4012 which contains L-alpha- phosphatidylcholine, dicetyl phosphate and cholesterol. Suitable positively charged liposome mixtures available from Sigma Chemical Company contains L-alpha-phosphatidylcholine, stearylamine and cholesterol (catalog numbers L-4137 and L-3887).

Categories of lipids in suitable liposomes are phospholipids, glycosphingolipids, ceramides, cholesterol sulfate and neutral lipids. Various combinations of these lipids are found in neonatal mouse, pig and human stratum granulosum and stratum corneum. Other categories of lipids which can be used to make the liposomes are straight chain fatty acids, glycerol esters, glycerides, phosphoglycerides, sphingolipids, waxes, terpenes and steroids. Specific preferred lipids suitable for use are phosphatidyl choline, dicetyl phosphate and cholesterol.

The liposomes may simply be used as the solvent for the PK-C Activators -i.e., after the liposomes are produced and isolated the PK-C Activator is added to the liposomes. The PK-C Activators may also be encapsulated in (or trapped in) the compartment portion of the liposome. This can be done by adding an aqueous solution of PK-C Activator to a suitable lipid and mixing (e.g., sonicating) to produce the liposomes containing the PK-C Activator. To make the aqueous solution of the PK-C Activator it may be desirable, as discussed above, to add additional water soluble components (e.g. alcohols, acetone, and the like) to increase the solubility of the PK-C Activator in the aqueous solution or to help maintain the PK-C Activator in the aqueous solution.

The PK-C Activators may also be added directly to a suitable lipid and mixed therewith so that there is a blend of PK-C Activators and lipid. Then when an aqueous solution is added to this blend and sonicated to produce the liposomes, the PK-C Activators will be in the lipid layer of the liposome and not the compartment of the liposome.

The liposome (as solvent) and PK-C Activator composition or the liposomes (PK-C Activator in compartment or lipid layer) can then be combined with a suitable topical vehicle, e.g. a lotion, gel or cream vehicle.

The lipid mixture which forms the liposome can be any of the conventional mixtures available or discussed in the literature which are pharmaceutically and cosmetically acceptable. Preferred lipid mixtures contain a phosphatidyl choline, dicetyl phosphate and cholesterol. The lipid mixtures which form the liposomes are commercially available in a solvent such as ethanol or chloroform. A typical mixture contains on a weight basis, seven parts phosphatidylcholine, 2 parts dicetyl phosphate and one part cholesterol.

If the PK-C Activator composition is not used immediately after made up, or frozen at about -20°C until use, then it is necessary to add an effective amount of at least one antioxidant to the composition to protect the PK-C Activator from degradation. Thus, if a PK-C Activator is used which will not degrade over time the antioxidant is no longer necessary, but its use is still preferred. Generally, about 0.05 to about 0.10% by weight of the composition of an antioxidant is sufficient. Any of the antioxidants known for use in the cosmetics industry may be used. Examples of antioxidants include but are not limited to beta- carotene, BHA, BHT, α-tocopherol, propyl gallate^", sodium bisulfate, sodium metabisulfate, ascorbyl dipalmitate, TENOX (trademark for food grade antioxidants containing one or more of the following ingredients: butylated hydroxyanisole, butylated hydroxytoluene, and/or propyl gallate with or without citric acid; some formulas are supplied in solvents such as propylene glycol); and the like. See, for example, the CTFA Cosmetic Ingredient Handbook cited above.

The PK-C Activator or PK-C Activator composition can be combined with a penetration enhancer to enhance the absorption of the Activator into the skin. The enhancer can be used in amounts of about 0.5% to about 99% by weight of the total composition with about 1% to about 25% being preferred and about 2% to about 10% being most preferred. Representative examples of penetration enhancers include, but are not limited to: DMSO (dimethyl sulfoxide), Azone (laurocapram, 1 -dodecylazacycloheptan-2-one, from Nelson Research, Irving, CA), N-methylpyrrolidone, alcohols such as panthenol, the SD alcohols and oleic alcohol, fatty acids such as oleic acid and linoleic acid, liposomes, and the like. Preferably, fatty acids are used. Other ingredients or components can be added to or combined (blended) with the PK-C Activator, or with the PK-C Activator composition formed from the PK-C Activator and solvents and/or penetration enhancers mentioned above. These other ingredients include, for example riboflavin, riboflavin phosphate, mixtures of riboflavin and riboflavin phosphate, DOPA phosphates (such as a mixture of monophosphorylated isomers of DOPA -see U.S. Patent No. 4,508,706, the disclosure of which is incorporated herein by reference thereto.), sunscreening agents, emollients, emulsifiers, solvents for sunscreening agents, waxes, thickeners, film formers, humectants, preservatives, surfactants, perfumes, biological additives, .buffering agents, chelating agents, emulsion stabilizers, opacifying agents, pH adjusters, propellants, coloring agents, and the like. The compositions can be formed into formulations, such as lotions, creams, gels, aerosols and sticks, in accordance with procedures well known in the art.

The PK-C Activators may conveniently be added to known vehicles (formulations) for sunscreening agents. The inclusion of the sunscreening agent would be optional.

Riboflavin, riboflavin phosphate or mixtures thereof may be used in amounts of at least about 0.05% by weight of the total composition. Generally riboflavin, riboflavin phosphate or mixtures thereof are used in an amount of about 0.1% to about 2% by weight of the total composition with about 0.1% to abut 0.3% being preferred and about 0.15% to about 0.3% being most preferred and about 0.2% to about 0.3% being even more preferred.

Conveniently, the riboflavin, riboflavin phosphate or mixtures thereof may be combined, along with the PK-C activators, with a known formulation (vehicle) for a sunscreening agent. The inclusion of the sunscreening agent would be optional. Normally, such a formulation contains effective amounts of water and a humectant (such as sorbitol as well as the other humectants discussed below). The humectant is usually present in amounts of about 1 to about 7% by weight of the total composition with about 4 to 5% being preferred. The water can be present in amounts such that the total amount of ingredients equals 100% by weight. Thus, for example with the inclusion of optional ingredients, the water may be present in amounts of about 40 to about 86% by weight of the total composition. The riboflavin, riboflavin phosphate or mixtures thereof may also be encapsulated in liposomes.

DOPA phosphates can be used in amounts of about 0.005 to about 1.0% by weight of the total composition with about 0.015 to about 0.5 being preferred and about 0.05 to about 0.29 being most preferred. The DOPA phosphates (phosphodopas) are O- phosphorylated derivatives of DOPA. The DOPA phosphates are represented by Formulas I-V:

wherein R¹ and R² each represent hydrogen or

or R1 and R² together represent

wherein R⁴ and R³ each represent hydrogen or a pharmaceutically acceptable cation; with the provisos that R¹ and R² cannot both be hydrogen. The sunscreening agents used can be of the UVA type, UVB type, or a combination of both. Generally, the sunscreening agents are used in amounts effective to provide the desired level of protection against UVA and/or UVB radiation. Usually, the sunscreening agents are used in amounts of about 2% to about 20% by weight of the total composition with about 5% to about 18% being preferred and about 2% to about 15% being most preferred.

Typical UVB type sunscreening agents include substituted para-aminobenzoates, alkyl esters of para- methoxycinnamate and certain esters of salicylic acid.

Typical UVA type sunscreening agents include certain benzυphenones and dibenzoyl methanes.

. Representative UVB type sunscreening agents include but are not limited to:

(A) DEA Methoxyinnamate (diethanolamine salt of p- methoxy hydro cinnamate), e.g., tradename BERNEL HYDRO from Bernel Chemical Co., Inc.;

(B) Ethyl Dihydroxypropyl PABA (ethyl dihydroxypropyl p-aminobenzoate), e.g., tradename AMERSCREEN P from Amerchol Corp.;

(C) Glyceryl PABA (glyceryl-p-aminobenzoate), e.g., tradename NIPA G.M.P.A. from NIPA Laboratories,

Inc.;

(D) Homosalate (Homomenthyl salicylate), e.g., tradename KEMESTER HMS from Humko Chemical; (E) Octocrylene (2-ethylhexyl-2-cyano-3,3- diphenylacrylate), e.g., tradename UVINUL N-539 from BASF Chemical Co.;

(F) Octyl Dimethyl PABA (Octyl dimethyl p- aminobenzoate, 2-ethylhexyl p- dimethylaminobenzoate, Padimate O), e.g., tradenames AMERSCOL, ARLATONE UVB, and ESCALOL 507 from Amerchol Corp., ICI Americas, Inc., and Van Dyk, respectively;

(G) Octyl Methoxycinnamate (2-ethylhexyl-p- methoxycinnamate), e.g., tradename PARSOL MCX from Bernel Chemical Co. Inc., or Givaudan Corp.;

(H) Octyl Salicylate (2-ethylhexy salicylate), e.g., tradename SUNAROME WMO from Felton Worldwide, Inc.;

(I) PABA (p-amino benzoic acid), e.g., tradename

PABA from EM Industries, Inc. and National Starch & Chemical Corp., or tradename NIPA PABA from NIPA Laboratories Inc.;

(J) 2-Phenyl-benzimidazole-5-Sulphonic acid

(Novantisol), e.g., tradename EUSOLEX 232 and NEO-HELIOPAN HYDRO from EM Industries, Inc. and Haarmann & Reimer Corp., respectively;

(K) TEA Salicylate (triethanolamine salicylate), e.g., tradenames SUNAROME W and SUNAROME G from Felton Worldwide, Inc.; (L) 3-(4-methylbenzlidene)camphor or 3-(4- methylbenzyIidene)boran-2-one, e.g., tradename EUSOLEX 6300 from EM Industries, Inc.; and

(M) Etocrylene (2-ethyl-2-cyano-3,3'- diphenylacrylate), e.g., tradename UVINUL N-35 from BASF Chemical Co.

Representative UVA type sunscreening agents include but are not limited to:

(A) Benzophenone-3 (2-hydroxy-4-methoxy- benzophenone), e.g., tradename SPECTRA-SORB UV- 9 and UVINUL M-40 from American Cyanamid Co. and BASF Chemical Co., respectively;

(B) Benzophenone-4 (sulisobenzone), e.g., tradename UVINUL MS-40 from BASF Chemical Co.;

(C) Benzophenone-8 (dioxybenzone), e.g., tradename SPECTRA-SORB UV-24 from American Cyanamid Co.;

(D) Menthyl Anthranilate (Menthyl-O-aminobenzoate), e.g., tradename SUNAROME UVA from Felton Worldwide, Inc.;

(E) Benzophenone-1 (2,4-dihydroxybenzophenone), e.g., tradename UVINUL 400 and UVASORB 2 OH from

BASF Chemical Co. and TRI-K Industries, Inc., respectively; (F) Benzophenone-2 (2,2',4,4'-tetrahydroxy- benzohpenone), e.g., tradename UVINUL D-50 from BASF Chemical Co.;

(G) Benzophenone-6 (2,2'-dihydroxy-4,4'-dimethoxy- benzoph^'enone), e.g., tradename UVINUL D-49 from BASF Chemical Co.;

(H) Benzophenone-12 (octabenzone), e.g., tradename

UVINOL 408 from BASF Chemical Co.;

(I) 4-isopropyl dibenzoyl methane (1 -p-cumenyl-3- phenylpropane-1 ,3-dione), e.g. tradename EUSOLEX 8020 from EM Industries, Inc.; and

(J) Butyl methyl dibenzoyl methane (4-t-butyl-4'- methoxydibenzoyl methane), e.g. tradename PARSOL 1789 from Givaudan Corporation;

Physical sunscreening agents may also be used. For example, red petrolatum in amounts of about 30 to about 99% by weight of the total composition, or titanium dioxide in amounts of about 2 to about 25% by weight of the total composition may be - used. Talc, kaolin, chalk, and precipitated silica may also be used in effective amounts, e.g., about 1% to about 10% by weight of the total composition.

Additional sunscreening agents include lawsone (hydroxynaphthoquinone, C10H6O3, the coloring matter of henna leaves) with dihydroxy acetone.

Usually, when used, at least one UVB type and at least one UVA type sunscreening agent is used. For example, at least one of the following UVB type sunscreening agents can be used: from about 1.5 to about 8.0% by weight of the total composition of octyl dimethyl PABA; octyl para- methoxycinnamate in amounts of about 1.5 to about 7.5% by weight of the total composition; homomenthyl salicylate in amounts of about 4.0 to about 15% by weight of the total composition; and octyl salicylate in amounts of about 3 to about 5% by weight of the total composition.

Also, for example, at least one of the following UVA type sunscreening agents can be used: ben ophenone-3 in amounts of about 0.5 to about 6% by weight of the total composition; benzophenone-8 in amounts of about 0.5 to about 3% by weight of the total composition; and menthyl anthranϋate in amounts of about 3.5 to about 5.0% by weight of the total composition. Using the other ingredients disclosed above, the PK-C

Activators or PK-C Activator compositions can be incorporated into formulations such as lotions, creams, gels mousses, waxed based sticks, aerosols, alcohol sticks and the like. These formulations are well known in the art, for example see Balsam, M.S., and Sagrin, E. (Editors) Cosmetics Science and Technology. Second Edition, Volumes 1 and 2, Wiley-lnterscience, a division of John Wiley & Sons, Inc., New York, copyright 1972; and Flick, E.W., Cosmetic and Toiletry Formulations, Noyes Publications, 1984.

Emollients may be used in amounts which are effective to prevent or relieve dryness. Useful emollients may include: hydrocarbon oils and waxes; silicone oils; triglyceride esters; acetoglyceride esters; ethoxylated glyceride; alkyl esters; alkenyl esters; fatty acids; fatty alcohols; fatty alcohol ethers; ether- esters; lanolin and derivatives; polyhydric alcohols (polyols) and polyether derivatives; polyhydric alcohol (polyol) esters; wax esters; beeswax derivatives; vegetable waxes; phospholipids; sterols; and amides. Thus, for example, typical emollients include mineral oil, especially mineral oils having a viscosity in the range of 50 to 500 SUS, lanolin oil, mink oil, coconut oil, cocoa butter, olive oil, almond oil, macadamia nut oil, aloe extract, jojoba oil, safflower oil, corn oil, liquid lanolin, cottonseed oil, peanut oil, purcellin oil, perhydrosqualene (squalene), caster oil, polybutene, odorless mineral spirits, sweet almond oil, avocado oil, calophyllum oil, ricin oil, vitamin E acetate, olive oil, mineral spirits, cetearyl alcohol (mixture of fatty alcohols consisting predominantly of cetyl and stearyl alcohols), linolenic alcohol, oleyl alcohol, octyl dodecanol, the oil of cereal germs such as the oil of wheat germ cetearyl octanoate (ester of cetearyl alcohol and 2-ethylhexanoic acid), cetyl palmitate, diisopropyl adipate, isopropyl palmitate, octyl palmitate, isopropyl myristate, butyl myristate, glyceryl stearate, hexadecyl stearate, isocetyl stearate, octyl stearate, octylhydroxy stearate, propylene glycol stearate, butyl stearate, decyl oleate, glyceryl oleate, acetyl glycerides, the octanoates and benzoates of (C12-C 5) alcohols, the octanoates and decanoates of alcohols and polyalcohols such as those of glycol and glycerol, and ricin- oleates of alcohols and poly alcohols such as those of isopropyl adipate, hexyl laurate, octyl dodecanoate, dimethicone copolyol, dimethiconol, lanolin, lanolin alcohol, lanolin wax, hydrogenated lanolin, hydroxylated lanolin, acetylated lanolin, petrolatum, isopropyl ianolate, cetyl myristate, glyceryl myristate, myristyl myristate, myristyl lactate, cetyl alcohol, isostearyl alcohol stearyl alcohol, and isocetyl Ianolate, and the like. Emulsifiers (emulsifying agents) may be used in amounts effective to provide uniform blending of ingredients of the composition. Useful emulsifiers may include A. Anionics

1. Fatty acid soaps, e.g., potassium stearate, sodium stearate, ammonium stearate, and triethanolamine stearate; 2. Polyol fatty acid monoesters containing fatty acid soaps, e.g., glycerol monostearate containing either potassium or sodium salt;

3. Sulfuric esters (sodium salts), e.g., sodium lauryl sulfate, and sodium cetyl sulfate; and

4. Polyol fatty acid monoesters containing sulfuric esters, e.g., glyceryl monostearate containing sodium lauryl sulfate;

B. Cationics 1. N(stearoyl colamino formylmethyl) pyridium chloride;

2. N-soya-N-ethyl morpholinium ethosulfate;

3. Alkyl dimethyl benzyl ammonium chloride;

4. diisobutylphenoxytheoxyethyl dimethyl benzyl ammonium chloride; and

5. cetyl pyridium chloride;

C. Nonionics

1. polyoxyethylene fatty alcohol ethers, e.g., polyoxyethylene lauryl alcohol; 2. polyoxypropylene fatty alcohol ethers, e.g., propoxylated oleyl alcohol;

3. polyoxyethylene fatty acid esters, e.g., polyoxyethylene stearate;

4. polyoxyethylene sorbitan fatty acid esters, e.g , polyoxyethylene sorbitan monostearate;

5. sorbitan fatty acid esters, e.g., sorbitan monostearate;

6. polyoxyethylene glycol fatty acid esters, e.g., polyoxyethylene glycol monostearate; 7. polyol fatty acid esters, e.g., glyceryl monostearate and propylene glycol monostearate; and 8. ethoxylated lanolin derivatives, e.g., ethoxylated lanolins, ethoxylated lanolin alcohols and ethoxylated cholesterol.

Surfactants may also be used in the compositions of this invention. Suitable surfactants may include those generally grouped as cleansing agents, emulsifying agents, foam boosters, hydrotropes, solubilizing agents, suspending agents and nonsurfactants (facilitates the dispersion of solids in liquids). The surfactants are usually classified as amphoteric, anionic, cationic and nonionic surfactants. Amphoteric surfactants include acylamino acids and derivatives and N-alkylamino acids.

Anionic surfactants include: acylamino acids and salts, such as, acylglutamates, acylpeptides, acylsarcosinates, and acyltaurates; carboxylic acids and salts, such as, alkanoic acids, ester carboxylic acids, and ether carboxylic acids; sulfonic acids and salts, such as, acyl isethionates, alkylaryl sulfonates, alkyl sulfonates, and sulfosuccinates; sulfuric acid esters, such as, alkyl ether sulfates and alkyl sulfates.

Cationic surfactants include: alkylamines, alkyl imidazolines, ethoxylated amines, and quaternaries (such as, alkylbenzyldimethylammonium salts, alkyl betaines, heterocyclic ammonium salts, and tetra alkylammonium salts).

Nonionic surfactants include: alcohols, such as primary alcohols containing 8 to 18 carbon atoms; alkanolamides such as alkanolamine derived amides and ethoxylated amides; amine oxides; esters such as ethoxylated carboxylic acids, ethoxylated glycerides, glycol esters and derivatives, monoglycerides, polyglyceryl. esters, polyhydric alcohol esters and ethers, sorbitan/sorbitol esters, and triesters of phosphoric acid; and ethers such as ethoxylated alcohols, ethoxylated lanolin, ethoxylated polysiloxanes, and propoxylated polyoxyethylene ethers. Useful solvents for sunscreening agents include those solvents already disclosed as being useful solvents for the PK-C Activators.

Suitable waxes which may prove useful include: animal waxes, such as beeswax, spermaceti, or wool wax (lanolin); plant waxes, such as carnauba or candelilla; mineral waxes, such as montan wax or ozokerite; and petroleum waxes, such as paraffin wax and microcrystalline wax (a high molecular weight petroleum wax). Animal, plant, and some mineral waxes are primarily esters of a high molecular weight fatty alcohol with a high molecular weight fatty acid. For example, the hexadecanoic acid ester of tricontanol is commonly reported to be a major component of beeswax.

Suitable waxes which may be useful also include the synthetic waxes including polyethylene polyoxyethylene and hydrocarbon waxes derived from carbon monoxide and hydrogen (Fischer-Tropsch synthesis).

Representative waxes also include: ceresin; cetyl esters; hydrogenated jojoba oil; hydrogenated jojoba wax; hydrogenated rice bran wax; Japan wax; jojoba butter; jojoba oil; jojoba wax; munk wax; montan acid wax; ouricury wax; rice bran wax; shellac wax; sufurized jojoba oil; synthetic beeswax; synthetic jojoba oils; trihydroxystearin; cetyl alcohol; stearyl alcohol; cocoa butter; fatty acids of lanolin; mono-, di- and triglycerides which are solid at 25°C, e.g., glyceyl tribehenate (a triester of behenic acid and glycerine) and C18-C36 acid triglyceride (a mixture of triesters of C18-C36 carboxylic acids and glycerine) available from Croda, Inc., New York, NY under the tradenames Syncrowax HRC and Syncrowax HGL-C, respectively; fatty esters which are solid at 25°C; silicone waxes such as methyloctadecaneoxypolysiloxane and poly (dimethylsiloxy) stearoxysiloxane; stearyl mono- and diethanolamide; rosin and its derivatives such as the abietates of .glycol and glycerol; hydrogenated oils solid at 25°C; and sucroglycerides.

Thickeners (viscosity control agents) which may be used in effective amounts in aqueous systems include: algin; carbomers such as carbomer 934, 934P, 940 and 941 ; cellulose gum; cetearyl alcohol, cocamide DEA, dextrin; gelatin; hydroxyethylcellulose; hydroxypropylcellulose; hydroxypropyl methylcellulose; magnesium aluminum silicate; myristyl alcohol; oat flour; oleamide DEA; oleyl alcohol; PEG-7M; PEG-14M; PEG-90M; stearamide DEA; Stearamide MEA; stearyl alcohol; tragacanth gum; wheat starch; xanthan gum; and the like.

In the above list of thickeners, DEA is diethanolamine, and MEA is monoethanolamine. thickeners (viscosity control agents) which may be used in effective amounts in nonaqueous systems include, aluminum stearates; beeswax; candelilla wax; carnauba; ceresin; cetearyl alcohol; cetyl alcohol; cholesterol; hydrated silica; hydrogenated castor oil; hydrogenated cottonseed oil; hydrogenated soybean oil; hydrogenated tallow glyceride; hydrogenated vegetable oil; hydroxypropyl cellulose; lanolin alcohol; myristyl alcohol; octyldodecyl stearoyl sulfate; oleyl alcohol; ozokerite; microcystalline wax; paraffin; pentaerythrityl tetraoctanoate; polyacrylamide; polybutene; polyethylene; propylene glycol dicaprylate; propylene glycol dipelargonate; stearalkonium hectorite; stearyl alcohol; stearyl stearate; synthetic beeswax; trihydroxystearin; trilinolein; tristearin; zinc stearate; and the like.

Suitable film formers which may be used include: acrylamide/sodium acrylate copolymer; ammonium acrylates copolymer; Balsam Peru; cellulose gum; ethylene/maleic anhydride copolymer; hydroxyethylcellulose; hydroxypropylcellulose; polyacrylamide; polyethylene; polyvinyl alcohol; pvm/MA copolymer (polyvinyl methylether/ maleic anhydride); PVP

(polyvinylpyrrolidone); maleic anhydride copolymer such as PA-18 available from Gulf Science and Technology; PVP/hexadecene copolymer such as Ganex V-216 available from GAF Corporation; acrylic/acryiate copolymer; and the like.

Generally, film formers can be used in amounts of about

0.1% to about 10% by weight of the total composition with about 1 % to about 8% being preferred and about 0.1% to about 5% being most preferred. Humectants which may be used in effective amounts include: fructose; glucose; glulamic acid; glycerin; honey; maltitol; methyl gluceth-10; methyl gluceth-20; propylene glycol; sodium lactate; sucrose; and the like.

Preservatives which may be used in effective amounts include: butylparaben; ethylparaben; imidazolidinyl urea; methylparaben; O-phenylphenol; propylparaben; quatemium-14; quaternium-15; sodium dehydroacetate; zinc pyrithione; and the like.

The preservatives are used in amounts effective to prevent or retard microbial growth. Generally, the preservatives are used in amounts of about 0.1% to about 1 % by weight of the total composition with about 0.1% to about 0.8% being preferred and about 0.1% to about 0.5% being most preferred.

Perfumes (fragrance components) and colorants (coloring agents) well known to those skilled in the art may be used in effective amounts to impart the desired fragrance and color to the compositions of this invention.

Other ingredients which may by added or used in amounts effective for their intended use include: biological additives to enhance performance or consumer appeal such as amino acids, proteins, vanilla, aloe extract, bioflavinoids, and the like; buffering agents; chelating agents such as EDTA; emulsion stabilizers; pH adjusters; opacifying agents; and propellants such as butane carbon dioxide, ethane, hydrochlorofluorocarbons 22 and 142b, hydrofluorocarbon 152a, isobutane, isopentane, nitrogen, nitrous oxide, pentane, propane, and the like. The other ingredients -sunscreening agents, emollients, emulsifiers, surfactants, solvents for sunscreening agents, waxes, thickeners, film formers, humectants, preservatives, surfactants, perfumes, coloring agents, biological additives, buffering agents, chelating agents, emulsion stabilizers, opacifying agents, pH adjusters, and propellants- are all well known to those skilled in the art, and the determination of which ingredients to use to obtain the intended formulations, and the determination of the amounts which may be used to achieve the intended functions and effects of these ingredients are well within the capabilities of those skilled in the art without the need for undue experimentation. Further information may be obtained on these ingredients by reference to:

(1 ) Cosmetics & Toiletries, Vol. 102, No. 3, March 1987;

(2) Balsam, M.S., et al., editors, Cosmetics Science and Technology, 2nd edition, Vol. 1 , pp 27-104 and 179-222 Wiley-lnterscience, New York, 1972;

(3) Cosmetics & Toiletries, Vol. 104, pp 67-111 , February -1989;

(4) Cosmetics & Toiletries, Vol. 103, No. 12, pp 100- 129, December 1988; and (5) Nikitakis, J.M., editor, CTFA Cosmetic Ingredient Handbrook, First Edition, published by The Cosmetic, Toiletry and Fragrance Association, Inc., Washington, D.C., 1988.

the disclosures of each being incorporated herein by reference thereto.

By using effective amounts of the exemplified components various types of creams, lotions, gels, solid sticks, and aerosol formulations can be blended in accordance with known compositions and procedures. In making the formulations the PK-C Activators should not be heated and the PK-C Activators should not be^' subjected to high alkaline conditions. If riboflavin, riboflavin phosphate or mixtures thereof are used it is preferred that these ingredients not be heated nor subjected to high alkaline conditions. For example, a typical lotion formulation is listed in Table 1.

Table 1 TYPICAL LOTION FORMULATION

Ingredients

Part 1

Lanolin

Cocoa Butter

Emcol RHT (Glyceryl Stearate)¹

Hystrene 5016 (Stearic Acid)²

Vitamin E Acetate

Aloe Vera Lipo Quinone Extract

Jojoba Oil

Mineral Oil

Propylparaben

Medical Fluid 360 (Dimethicone)³

Part 2 Water Carbopol 941 (1%) (Polyacrylic Acid

Polymer)^** Propylene Glycol Triethanolamine 99% Lanogel 41 (PEG-75 Lanolin)⁵ Methylparaben Sequestrene Na2

Part 3

Perfume 0.01 % - 0.5%

1 Witco Corp., Organics Division, NY, NY (also Witconol RHT)

2 Humko Chemcal, Memphis, Tenn. 3 Dow Corning Corp., Midland, Michigan

4 B.F. Goodrich Specialty Polymers and Chemical Division,

Cleveland, Ohio

5 Amerchol Corp., Edison, NJ

To make the formulation listed in Table 1 parts 1 and 2 are heated separately to 180°F. Part 1 is then added to Part 2. The resultant blend is cooled to 120°F and Part 3 is then added.

Examples of formulations which may prove useful which are oil-in-water creams, oil-in-water lotions, - water-in-oil lotions, oil-in-water resistant creams and lotions, sticks, gels, oils and mousses may be found in, for example, Cosmetics & Toiletries, Vol. 102, pp 117-130, March 1987, the disclosure of which is incorporated herein by reference thereto. Examples of formulations which may prove useful which are hand and body lotions, oii-in-water emollient creams, moisturizing lotions, after sun emollient stick, facial spray mist,- skin mousse and moisturizing gel may be found, for example, in Cosmetics & Toiletries, Vol. 102, pp 147-160, April 1987, the disclosure of which is incorporated herein by reference thereto. Those skilled in the art will appreciate that the formulations described in the above cited Cosmetics & Toiletries references (March and April 1987) represent types of formulations which may be suitably modified to allow for the addition of PK-C Activators and antioxidants, and that such modifications may be accomplished without the need for undue experimentation.

The following examples are illustrative only and should not be construed as limiting the invention in any way. Those skilled in the art will appreciate that variations are possible which are within the spirit and scope of the appended claims.

EXAMPLE 1 PAG ± UV

Forty female Skh-2 mice (obtained from Skin and Cancer

Hospital, Philadelphia, PA) were randomly assigned to treatment groups of ten each. Two groups received 1 ,2-Sn-dioctanoylglycerol topically in acetone at 1.75 μ mole/dose (0.5 mg/ml in 100 μl) twice weekly (Tuesday and Thursday) over their dorsal surface (12 cm²) while the remaining two groups received acetone only. One group receiving each topical treatment also received UV irradiation 3 times weekly (Monday, Wednesday and Friday) from a bank of Kodacel 401 -filtered FS20 lamps.- A total of 9 irradiations was given at approximately 0.8 MED/dose (MED is an abbreviation for "minimal erythermal dose" which is that amount of radiation needed to produce a barely perceptible response). Skin samples from the dorsum were stained with either DOPA or Warthin-Starry melanin stains or with Mowry's (acid mucopolysaccharides) or H&E (hematoxylin and eosin) to document irritation in accordance with procedures well known to those skilled in the art (see, for example, Luna, L., Manual of Histologic Staining Methods of the Armed. Forces Institute of Pathology. McGraw-Hill Book Co., New York, 1968).

Data from the histological slides were obtained by image analysis.

Statistical analysis revealed that the Warthin-Starry and DOPA stain data correlated well and therefore both data sets were anlyzed collectively. The 1 ,2-Sn-dioctanoylglycerol treatment resulted in significantly enhanced melanogenesis in both the irradiated and the non-irradiated groups. While the tanning which resulted from the topical use of 1 ,2-Sn-dioctanoylglycerol alone was not as dark as that achieved by the UV alone, it was visually apparent. The level of tanning achieved with 1 ,2-Sn- dioctanoylglycerol plus UV was significantly different (i.e., more melanin was measured in the skin sections by image analysis) from that achieved with either UV or 1 ,2-Sn-dioctanoylglycerol alone. H&E and Mowry's staining revealed no irritation to the skin.

EXAMPLE 2

Pose-response without UV

1 ,2-sn-Dioctanoylglycerol in acetone was studied at four concentrations, 1.75 μmole to 3.50 μmole/dose (0.5, 2.5, 5 and 10 mg/ml), without added UV. Topical applications were made 3 times weekly (Monday, Wednesday and Friday) for 3 weeks to 40 female Skh-2 mice, 10 mice/group, (obtained from Skin and Cancer Hospital, Philadelphia, PA). Evaluation of the histological slides image analysis was followed by statistical analysis of the data. No visible irritation resulted from the 1 ,2-Sn- dioctanoylglycerol applications.

The DOPA-stained slides of whole epidermis revealed many highly dendritic melanocytes with nodular areas along the dendrites in the groups treated with the 1 ,2-Sn-dioctanoylglycer The control group epidermis in contrast contained few active melanocytes. The DOPA stain is a sensitive assay of tyrosinase enzyme activity.

The Warthin-Stany stain (thin sections) deposits silv on pre-formed melanin. It is, therefore, measuring a different parameter than is measured by the DOPA stain. The treatment w 1 ,2-Sn-dioctanoylglycerol resulted in only minimally enhanced production of melanin, although the treated groups each containe more melanin than did the control group. The Warthin-Starry sta revealed that the increased tyrosinase activity detected by the DOPA stain had not been fully translated into melanin production the time the experiment ended. These results demonstrate that t cells were primed for increased production of melanin in comparison to the controls. It is believed that if the experiment was run for a longer period of time melanin production would hav progressed. Those skilled in the art will appreciate that the total amount of all ingredients (components) used in the composition this invention equals 100% by weight of the total composition. Also, unless stated otherwise all percents and amounts are perc by weight of the total composition. The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are to be regarded as a departure from the spirit and scope of the invention and all such modifications are intended to be included within the scope of the claims.

Claims

WHAT IS CI AIMFD IS-

1. A composition comprising:

(a) at least one Protein Kinase C Activator present in an amount effective to enhance melanin production when said composition is applied topically to the skin, and

(b) at least one physiologically acceptable solvent for said Activator.

2. The composition of Claim 1 wherein there is added to said composition an effective amount of at least one other ingredient selected from the group consisting of: riboflavin, riboflavin phosphate, mixtures of riboflavin and riboflavin phosphate, DOPA phosphates, sunscreening agents, emollients, emulsifiers, solvents for sunscreening agents, waxes, thickeners, film formers, humectants, antioxidants, preservatives, surfactants, skin penetration enhancers, perfumes, biological additives, buffering agents, chelating agents, emulsion stabilizers, opacifying agents, pH adjusters, propellants and coloring agents.

3. The composition of Claim 2 wherein there is added to said composition an effective amount of an antioxidant.

4. The composition of Claim 3 wherein there is added to said composition an effective amount of riboflavin.

5. The composition of Claim 4 wherein there is added to said composition an effective amount of at least one sunscreening agent.

6. The composition of Claim 1 wherein said Activator is selected from the group consisting of: 54

diacylglycerols, triacylglycerols, lipopolysaccharides, unsaturated free fatty acids, short chain free fatty acids, enzymes which hydrolyze glycophospholipids to diacylglycerols, bryostatins and glycerolphospholipids.

7. The composition of Claim 1 wherein said Activator is diacylglycerol.

8. The composition of Claim 7 wherein said diacylglycerol is selected from the group consisting of:

(a) 1 ,2-dioctanoyl glycerol;

(b) 1 ,2-didecanoyl glycerol;

(c) 1 -oleoyl-2-acetyl glycerol; (d) 1 -acetyl-2-oleoyl glycerol;

(e) 1 ,2-dihexanoyl glycerol;

(f) 1 -stearyl-2-arachidonyl glycerol;

(g) 1 -stearyl-2-oleoyl glycerol; (h) 1 ,2-dipalmitoyl glycerol; (i) 1 ,2-distearyl glycerol;

(j ) 1 ,2-dioleoyl glycerol;

(k) diarachidonin;

(I) diolein;

(m) dipalmitin; and (n) distearin.

9. The composition of Claim 7 wherein said diacylglycerol is a diacyl-sn-glycerol.

10. The composition of Claim 9 wherein said diacylglycerol is 1 ,2-dioctanyl-sn-glycerol.

1 1. The composition of Claim 7 wherein there is added to said composition at least one Activator selected from the group consisting of: triacylglycerols, glycerophospholipids, lipopolysaccharides, unsaturated free fatty acids, saturated short chain fatty acids, phospholipase C, and bryostatins.

12. A method of enhancing melanin production comprising applying topically to the skin a composition of any of Claims 1-11.

13. The use of a composition of any of Claims 1-11 to manufacture a composition for enhancing melanin production when applied topically to the skin.

14. The use of a composition of any of Claims 1-11 to enhance the production of melanin when said composition is applied topically to the skin.

15. A process for producing a composition for enhancing melanin production when said composition is applied to the skin comprising combining at least one Protein Kinase C activator with a suitable solvent.