Hydroxycitric acid derivatives and skin external preparations containing the same
Hydroxycitric acid derivatives and salts thereof are provided which are useful as active ingredients of skin external preparations and cosmetics. Also provided are processes for production of the hydroxycitric acid derivatives, and skin external preparations and cosmetics containing the hydroxycitric acid derivatives. Specific hydroxycitric acid derivatives or salts thereof are produced wherein at least one of the hydroxyl groups of hydroxycitric acid or least one of the hydroxyl groups and at least one carboxyl group of hydroxycitric acid are modified to linkage moieties breakable by biological enzyme reaction. The hydroxycitric acid derivatives or salts thereof are added in skin external preparations and cosmetics.
1. A hydroxycitric acid derivative represented by the formula (I) below or salt thereof:
wherein R 1 and R 2 are each a hydrogen atom or a group removable by biological enzyme reaction (with the proviso that R 1 and R 2 cannot be hydrogen atoms at the same time), the removable group being selected from those represented by the formula (Ia) below; X 1 to X 3 are each a nitrogen atom or an oxygen atom; and R 3 , R 4 , R 5 , R 3′ , R 4′ and R 5′ are each a hydrogen atom or a chain hydrocarbon group of 1 to 30 carbon atoms that may have a branch or an unsaturated bond (with the proviso that when any of X 1 , X 2 and X 3 is an oxygen atom, corresponding R 3′ , R 4′ or R 5′ does not exist);
wherein R 6 is a hydrogen atom, a phenyl group, a naphthyl group, a furyl group, a thienyl group, a pyridyl group, or a chain hydrocarbon group of 7 to 23 carbon atoms that may have a branch, an unsaturated bond or a substituent group selected from the group consisting of a halogen atom, an amino group, a cyano group, an alkoxy group and a nitro group, and R 7 and R 8 are each a hydrogen atom, an aryl group, or a chain hydrocarbon group of 1 to 30 carbon atoms that may have a branch, an unsaturated bond or a substituent group selected from the group consisting of a halogen atom, an amino group, a cyano group, an alkoxy group and a nitro group.
2. The hydroxycitric acid derivative or salt thereof according to claim 1 , wherein in the formula (Ia), R 6 is a chain hydrocarbon group of 7 to 23 carbon atoms that may have a branch, an unsaturated bond or a substituent group selected from the group consisting of a halogen atom, an amino group, a cyano group, an alkoxy group and a nitro group, and R 7 and R 8 are each a hydrogen atom or a chain hydrocarbon group of 8 to 24 carbon atoms that may have a branch, an unsaturated bond or a substituent group selected from the group consisting of a halogen atom, an amino group, a cyano group, an alkoxy group and a nitro group.
3. The hydroxycitric acid derivative or salt thereof according to claim 1 , wherein in the formula (I), R 3 to R 5 are each a hydrogen atom or a chain hydrocarbon group of 1 to 30 carbon atoms that may have a branch or an unsaturated bond, and X 1 to X 3 are all oxygen atoms; and
wherein in the formula (Ia), R 6 is a chain hydrocarbon group of 7 to 23 carbon atoms that may have a branch, an unsaturated bond or a substituent group selected from the group consisting of a halogen atom, an amino group, a cyano group, an alkoxy group and a nitro group, and R 7 and R 8 are each a hydrogen atom or a chain hydrocarbon group of 8 to 24 carbon atoms that may have a branch, an unsaturated bond or a substituent group selected from the group consisting of a halogen atom, an amino group, a cyano group, an alkoxy group and a nitro group.
4. The hydroxycitric acid derivative or salt thereof according to claim 1 , wherein in the formula (I), R 2 is a hydrogen atom, R 3 to R 5 are all hydrogen atoms, and X 1 to X 3 are all oxygen atoms; and
wherein in the formula (Ia), R 6 is a chain hydrocarbon group of 13 to 21 carbon atoms that may have a branch, an unsaturated bond or a substituent group selected from the group consisting of a halogen atom, an amino group, a cyano group, an alkoxy group and a nitro group.
5. The hydroxycitric acid derivative or salt thereof according to claim 1 , wherein in the formula (I), R 2 is a hydrogen atom, R 3 to R 5 are each a hydrogen atom or a chain hydrocarbon group of 1 to 30 carbon atoms that may have a branch or an unsaturated bond (with the proviso that R 3 to R 5 cannot be hydrogen atoms at the same time), and X 1 to X 3 are all oxygen atoms; and
wherein in the formula (Ia), R 6 is a chain hydrocarbon group of 13 to 21 carbon atoms that may have a branch, an unsaturated bond or a substituent group selected from the group consisting of a halogen atom, an amino group, a cyano group, an alkoxy group and a nitro group.
6. A process for producing the hydroxycitric acid derivative or salt thereof as described in claim 1 , which process comprises reacting hydroxycitric acid and/or an alkali metal salt thereof and/or an alkaline earth metal salt thereof, with a carboxylic acid derivative, a phosphoric acid derivative or a sulfonic acid derivative that is capable of in vivo cleavage, in a solvent.
7. A process for producing the hydroxycitric acid derivative or salt thereof as described in claim 4 , which process comprises:
a first step comprising reacting hydroxycitric acid and/or an alkali metal salt thereof and/or an alkaline earth metal salt thereof, with an alcohol in a solvent to prepare a hydroxycitric acid (tri)ester;
a second step comprising reacting the compound obtained in the first step with an aliphatic carboxylic acid derivative capable of in vivo cleavage to esterify a hydroxyl group of the compound obtained in the first step; and
a third step comprising cleaving ester linkage moieties of the compound obtained in the second step so as to cleave part or all of the ester linkage moieties formed in the first step.
8. A skin external preparation comprising the hydroxycitric acid derivative and/or salt thereof as described in claim 1 .
9. The skin external preparation according to claim 8 , wherein the preparation contains the hydroxycitric acid derivative and/or salt thereof in an amount of 0.01 to 20% by mass.
10. The skin external preparation according to claim 8 , wherein the preparation further contains a substance capable of increasing hormone-sensitive lipase activity.
11. The skin external preparation according to claim 8 , wherein the preparation further contains a substance capable of facilitating breakdown of fatty acids.
12. A cosmetic comprising the skin external preparation as described in claim 8 .
13. A process for producing the hydroxycitric acid derivative or salt thereof as described in claim 2 , which process comprises reacting hydroxycitric acid and/or an alkali metal salt thereof and/or an alkaline earth metal salt thereof, with a carboxylic acid derivative, a phosphoric acid derivative or a sulfonic acid derivative that is capable of in vivo cleavage, in a solvent.
14. A process for producing the hydroxycitric acid derivative or salt thereof as described in claim 3 , which process comprises reacting hydroxycitric acid and/or an alkali metal salt thereof and/or an alkaline earth metal salt thereof, with a carboxylic acid derivative, a phosphoric acid derivative or a sulfonic acid derivative that is capable of in vivo cleavage, in a solvent.
15. A process for producing the hydroxycitric acid derivative or salt thereof as described in claim 4 , which process comprises reacting hydroxycitric acid and/or an alkali metal salt thereof and/or an alkaline earth metal salt thereof, with a carboxylic acid derivative, a phosphoric acid derivative or a sulfonic acid derivative that is capable of in vivo cleavage, in a solvent.
16. A process for producing the hydroxycitric acid derivative or salt thereof as described in claim 5 , which process comprises reacting hydroxycitric acid and/or an alkali metal salt thereof and/or an alkaline earth metal salt thereof, with a carboxylic acid derivative, a phosphoric acid derivative or a sulfonic acid derivative that is capable of in vivo cleavage, in a solvent.
17. A process for producing the hydroxycitric acid derivative or salt thereof as described in claim 5 , which process comprises:
a first step comprising reacting hydroxycitric acid and/or an alkali metal salt thereof and/or an alkaline earth metal salt thereof, with an alcohol in a solvent to prepare a hydroxycitric acid (tri)ester;
a second step comprising reacting the compound obtained in the first step with an aliphatic carboxylic acid derivative capable of in vivo cleavage to esterify a hydroxyl group of the compound obtained in the first step; and
a third step comprising cleaving ester linkage moieties of the compound obtained in the second step so as to cleave part or all of the ester linkage moieties formed in the first step.
18. The skin external preparation according to claim 9 , wherein the preparation further contains a substance capable of increasing hormone-sensitive lipase activity.
19. The skin external preparation according to claim 9 , wherein the preparation further contains a substance capable of facilitating breakdown of fatty acids.
20. A cosmetic comprising the skin external preparation as described in claim 9 .
21. A cosmetic comprising the skin external preparation as described in claim 10 .
22. A cosmetic comprising the skin external preparation as described in claim 11 .
23. A cosmetic comprising the skin external preparation as described in claim 18 .
24. A cosmetic comprising the skin external preparation as described in claim 19 .