Ester derivatives of ascorbic and 2-keto acid saccharides

1. A compound comprising an ester derivative of ascorbic acid or 2-keto acid saccharide, wherein an ester has been introduced by an ester bond formation between an ascorbic acid or a 2-keto acid saccharide comprising at least one hydroxy-functional group and a carboxy-functional organosiloxane, wherein the ascorbic acid comprises either ascorbic acid or isoascorbic acid, or stereoisomers or salts thereof, and wherein the 2-keto acid saccharide comprises either 2-keto-L-gulonic acid or 2-keto-D-gluconic acid, or stereoisomers or salts thereof.

2. The compound as recited in claim 1 , wherein the organosiloxane comprises mono or bis-carboxy-functional organosiloxane, or a combination thereof.

3. The compound as recited in claim 1 , wherein the organosiloxane comprises pendant carboxy-functional organosiloxane.

4. The compound as recited in claim 1 , wherein the ester derivative comprises a 6-O acyl derivative of ascorbic acid.

5. The compound as recited in claim 1 , wherein the ester derivative comprises a 6-O acyl derivative of a methyl 2-keto acid saccharide.

6. The compound as recited in claim 1 , wherein the ascorbic acid comprises at least one hydroxy group which is functionalized or protected or both.

7. The compound as recited in claim 6 , wherein the at least one hydroxy group is protected by formation of an ester, an ether, or an epoxy.

8. The compound as recited in claim 7 , wherein the ester is selected from the group consisting of an O-acetate, an O-carbonate, and an O-phosphate.

9. The compound as recited in claim 7 , wherein the ether comprises a trimethylsilyl ether.

10. A compound as recited in claim 1 , wherein the compound comprises an ester derivative of ascorbic acid having the following structural formula:

and wherein: each P may independently be any protecting or functional group, a proton or a cation chosen from the alkali or alkaline earth metals; the stereochemical configurations of the fourth and/or fifth carbons of the ascorbic acid moieties are independently selected; s is either 0 or 1; m, n, and o may independently represent any integer between 0 and 300; l is any integer between 0 and 30; r is either 0 or 1; X may be CH 2 , CH 3 , OCH 2 [CH 2 ] l CH 2 , OCH 2 CH(CH 3 )CH 2 , (OCH 2 CH 2 ) m OCH 2 [CH 2 ] l CH 2 , (OCH(CH 3 )CH 2 ) m OCH 2 [CH 2 ] l CH 2 , NHCH 2 [CH 2 ] l CH 2 , NHCH 2 CH 2 NHCH 2 [CH 2 ] l CH 2 , NHCH 2 CH 2 NHCH 2 CH(CH 3 )CH 2 , (C═O)NHCH 2 [CH 2 ] l CH 2 , (C═O)NHCH 2 CH 2 NHCH 2 [CH 2 ] l CH 2 , or (C═O)NHCH 2 CH 2 NHCH 2 CH(CH 3 )CH 2 , and X may also be Y or Z; Y and Z are independently selected from H, OH, alkyl (C 1-12 ), carboxyalkyl (C 1-12 ), alkenyl (C 1-12 ), OSi(CH 3 ) 3 , [OSi(Y)(Z)] m OSi(X)(Y)(Z), and phenyl; and further wherein when s=1, Z′=O, and when s=0, Z′=Z.

11. A compound as recited in claim 1 , wherein the compound comprises an ester derivative of a 2-keto acid saccharide having the following structural formula:

and wherein: each P is independently be any protecting or functional group, a proton or a cation chosen from the alkali or alkaline earth metals; R is a lower alkyl (C1-6) or alkenyl (C1-6), a metal ion, NH 4 + or NH a (R) 4-a ; where R is lower alkyl (C1-6) and a is an integer from 0 to 4, the stereochemical configurations of the fourth and/or fifth carbons of the carbohydrate moieties are independently selected; s is either 0 or 1; m, n, and o may independently represent any integer between 0 and 300; l is any integer between 0 and 30; r is either 0 or 1; X may be CH 2 , CH 3 , OCH 2 [CH 2 ] l CH 2 , OCH 2 CH(CH 3 )CH 2 , (OCH 2 CH 2 ) m OCH 2 -[CH 2 ] l CH 2 , (OCH(CH 3 )CH 2 ) m OCH 2 [CH 2 ] l CH 2 , NHCH 2 [CH 2 ] l CH 2 , NHCH 2 CH 2 NHCH 2 [CH 2 ] l CH 2 , NHCH 2 CH 2 NHCH 2 CH(CH 3 )CH 2 , (C═O)NHCH 2 [CH 2 ] l CH 2 , (C═O)NHCH 2 CH 2 NHCH 2 [CH 2 ] l CH 2 , or (C═O)NHCH 2 CH 2 NHCH 2 CH(CH 3 )CH 2 , and X may also be Y or Z; Y and Z are independently selected from H, OH, alkyl (C1-12), carboxyalkyl (C1-12), alkenyl (C1-12), OSi(CH 3 ) 3 , [OSi(Y)(Z)] m OSi(X)(Y)(Z), and phenyl; and further wherein when s=1, Z′═O, and when s=0, Z′═Z.

12. A compound comprising an ester derivative of a 2-keto-acid saccharide, wherein an ester has been introduced by an ester bond formation between a 2-keto-gulonic acid and a carbinol-functional organosiloxane, and wherein the 2-keto acid saccharide comprises either 2-keto-L-gulonic acid or 2-keto-D-gluconic acid, or stereoisomers or salts thereof.

13. The compound as recited in claim 12 wherein the organosiloxane comprises a mono or bis-carbinol functional organosiloxane, or a combination thereof.

14. The compound as recited in claim 12 , wherein the 2-keto acid saccharide comprises at least one hydroxy group which is functionalized or protected or both.

15. The compound as recited in claim 14 , wherein the at least one hydroxy group is protected by formation of an ester, an ether, or an epoxy.

16. The compound as recited in claim 15 , wherein the ester is selected from the group consisting of an O-acetate, an O-carbonate, and an O-phosphate.

17. The compound as recited in claim 15 , wherein the ether comprises an isopropylidene ether.

18. A compound as recited in claim 12 having the following structural formula:

and wherein P may be any protecting or functional group or a proton, R may be a lower alkyl (C1-6) or alkenyl (C1-6), a metal ion, NH 4 + , or NH s (R) 4-s where R is lower alkyl (C1-6) and s is either 0 or 1, s is an integer from 0 to 4, the stereochemical configurations of the fourth and/or fifth carbons of the carbohydrate moieties are independently selected; m, n, o and p may be independently represented by any integer between 0 and 300, and l may be any integer between 1 and 30, X may be independently selected from the group consisting of CH 2 , CH 3 , OCH 2 [CH 2 ] l CH 2 , OCH 2 CH(CH 3 )CH 2 , (OCH 2 CH 2 ) m OCH 2 [CH 2 ] l CH 2 , (OCH(CH 3 )CH 2 ) m OCH 2 [CH 2 ] l CH 2 , NHCH 2 [CH 2 ] l CH 2 , NHCH 2 CH 2 NHCH 2 [CH 2 ] l CH 2 , NHCH 2 CH 2 NHCH 2 CH(CH 3 )CH 2 , (C═O)NHCH 2 [CH 2 ] l CH 2 , (C═O)NHCH 2 CH 2 NHCH 2 [CH 2 ] l CH 2 , (C═O)NHCH 2 CH 2 NHCH 2 CH(CH 3 )CH 2 , Y or Z, and Y and Z are independently selected from H, OH, alkyl (C1-12), alkenyl (C1-12), OSi(CH 3 ) 3 , [OSi(Y)(Z)] m OSi(X)(Y)(Z), and phenyl; and further wherein when s=1, Z′═O, and when s=0, Z′═Z.

19. A method for synthesizing the compound recited in claim 1 comprising:

a) providing a protected ascorbic acid or a protected 2-keto acid saccharide by forming a protecting group from at least one hydroxy-functional group thereon;

b) mixing the protected ascorbic acid or protected 2-keto acid saccharide with a carboxy-functional siloxane to form a solution;

c) contacting the solution with a biocatalyst which is capable of catalyzing ester bond formation;

d) optionally, removing the protecting group, and

wherein the protecting group may comprise a functional group.

20. The method as recited in claim 19 , wherein the protecting group comprises a trimethylsilyl ether.

21. The method as recited in claim 19 , wherein the carboxy-functional organosiloxane is mono- or bis-carboxy functional.

22. The method as recited in claim 19 , wherein the biocatalyst comprises an enzyme.

23. The method as recited in claim 22 , wherein the enzyme comprises a hydrolase enzyme.

24. The method as recited in claim 23 , wherein the hydrolase enzyme exits in either free or immobilized form and is selected from the group consisting of a lipase, a protease, a phosphoesterase, an esterase, a cutinase, and combinations thereof.

25. The method as recited in claim 24 , wherein the hydrolase enzyme comprises a lipase.

26. The method as recited in claim 25 , wherein the lipase comprises an immobilized form of Candida antarctica lipase B.

27. A method for synthesizing the compound recited in claim 12 comprising:

a) providing a protected 2-keto acid saccharide by forming a protecting group from at least one of the hydroxy-functional groups;

b) providing a mono or bis-carbinol-functional organosiloxane;

c) dissolving the protected 2-keto acid saccharide and the carbinol-functional organosiloxane in a suitable solvent to form a solution;

d) treating the solution with a biocatalyst which is capable of catalyzing ester bond formation;

e) optionally, removing the protecting group, and

wherein the protecting group may comprise a functional group.

28. The method as recited in claim 27 , wherein the protecting group comprises an alkylidene.

29. The method as recited in claim 28 , wherein the alkylidene comprises acetonide.

30. The method as recited in claim 27 , wherein the biocatalyst comprises an enzyme.

31. The method as recited in claim 30 , wherein the enzyme comprises a hydrolase enzyme.

32. The method as recited in claim 31 , wherein the hydrolase enzyme is selected from the group consisting of a lipase, a protease, a phosphoesterase, an esterase, a cutinase, and combinations thereof.

33. The method as recited in claim 32 , wherein the hydrolase enzyme comprises a lipase.

34. The method as recited in claim 33 , wherein the lipase comprises an immobilized form of Candida antarctica lipase B.

35. A controlled-release method of generating ascorbic acid comprising:

a) providing an ester derivative of 2-keto L-gulonic acid wherein the ester has been introduced by an ester bond formation between a 2-keto L-gulonic acid and a carbinol-functional organosiloxane;

b) delivering the acyl deriviative of 2-keto L-gulonic acid to an environment wherein an intramolecular lactonization reaction may occur, releasing free ascorbic acid and a carbinol-functional organosiloxane.

36. A composition comprising the compound as recited in claim 1 .

37. A composition according to claim 36 , further comprising free ascorbic acid.

38. A treatment or cosmetic formulation comprising: an ester derivative of 2-keto L-gulonic acid wherein the ester has been introduced by an ester bond formation between a 2-keto L-gulonic acid and a carbinol-functional organosiloxane; and a pharmaceutically or cosmetically suitable vehicle or base.

39. A keratinaceous tissue lightening agent comprising the compound recited in claim 1 .

40. The agent as recited in claim 39 , wherein the keratinaceous tissue comprises human skin.

41. A composition comprising: a safe and effective amount of the keratinaceous tissue lightening agent recited in claim 39 ; and a suitable vehicle or base.

42. The composition as recited in claim 41 , further comprising free ascorbic acid.

43. The composition as recited in claim 41 , wherein the compound has a degree of polymerization (DP) based on the values of s, m, n and o, further wherein s, m, n and o are varied so that the degree of polymerization ranges from 1 to about 300.

44. The composition as recited in claim 43 , wherein s, m, n and o are varied so that the degree of polymerization ranges from 1 to about 100.

45. The composition as recited in claim 44 , wherein s, m, n and o are varied so that the degree of polymerization ranges from 2 to about 20.

46. The composition as recited in claim 43 , wherein the compound comprises a bis-ascorbyl ester of a (10-carboxydecyl)-terminated polydimethylsiloxane, wherein l=9, X═CH 2 , Y═Z═CH 3 , Z′═O, s=1, n=0, and o=0, further wherein m=2, or m=13, on average.

47. The composition as recited in claim 41 , wherein the composition is in the form of an emulsion.

48. A method of lightening keratinaceous tissue comprising: topically applying the composition as recited in claim 41 to human skin.

49. A personal care composition comprising an ester derivative of ascorbic acid, wherein an ester has been introduced by an ester bond formation between an ascorbic acid comprising at least one hydroxy-functional group and a carboxy-functional organosiloxane, wherein the ascorbic acid comprises either ascorbic acid or isoascorbic acid, or stereoisomers or salts thereof.

50. A personal care composition comprising the compound as recited in claim 6 wherein the functionalized hydroxy group imparts an additional beneficial property.