Use of guaiol for treating the skin
The use is described of compositions comprising (a) (−)-guaiol, (b) further skin-lightening active substance(s) and, optionally, (c) one or more UV-A and/or UV-B absorbers as melanogenesis inhibitors and for skin-lightening.
1. A method of inhibiting melanogenesis, which comprises contacting skin with an effective amount of a composition comprising
(a) (−)-guaiol which originates from Callitris intratropica and
(b) further skin-lightening active substance(s) selected from the group consisting of quercitin, aloesin, azelaic acid and esters thereof.
2. A method according to claim 1 , wherein the ratio of component (a):(b) is from 1:99 to 99:1% by weight of component (b).
3. A method according to claim 1 , wherein the composition additionally comprises, as component (c), one or more UV-A and/or UV-B absorbers.
4. A method according to claim 3 , wherein as UV-A and/or UV-B absorber there is used a compound of formula
wherein
R 1 and R 2 are each independently of the other C 3 -C 18 alkyl; C 2 -C 18 alkenyl; a radical of formula —CH 2 —CH(—OH)—CH 2 —O—T 1 ; or
R 1 and R 2 are a radical of formula
R 12 is a direct bond; a straight-chain or branched C 1 -C 4 alkylene radical or a radical of formula —C m 1 H 2m 1 — or —C m 1 H 2m 1 —O—;
R 13 , R 14 and R 15 are independently of the others C 1 -C 18 alkyl; C 1 -C 18 alkoxy or a radical of formula
R 16 is C 1 -C 5 alkyl;
m 1 and m 3 are each independently of the other from 1 to 4;
p 1 is 0 or a number from 1 to 5;
A 1 is a radical of formula
R 3 is hydrogen; C 1 -C 10 alkyl; —(CH 2 CHR 5 —O) n 1 —R 4 ; or a radical of formula —CH 2 —CH(—OH)—CH 2 —O—T 1 ;
R 4 is hydrogen; M; C 1 -C 5 alkyl; or a radical of formula —(CH 2 ) m 2 —O—T 1 ;
R 5 is hydrogen; or methyl;
T 1 is hydrogen; or C 1 -C 8 alkyl;
Q 1 is C 1 -C 18 alkyl;
M is a metal cation;
m 2 is from 1 to 4; and
n 1 is 1-16.
5. A method according to claim 4 , wherein the composition comprises, as component (c), the compound of formula
6. A method according to claim 1 , wherein the composition comprises, as component (c), the compound of formula
T 2 is C 1 -C 12 alkyl.
7. A method according to claim 6 , wherein T 2 is iso-octyl.
8. A method according to claim 1 , wherein the composition comprises, as component (c), octyl methoxycinnamate.
9. A method according to claim 1 , wherein the composition comprises, as component (c), benzophenone 3.
10. A method according to claim 1 whereby skin is lightened.
11. A method in which a composition according to claim 1 is incorporated into a cosmetic formulation.
12. A method according to claim 11 , wherein the composition is in the form of an oil-in-water formulation, in a solvent formulation or in the form of a paste formulation.
13. A method according to claim 11 , wherein the amount of the composition in the formulation is from 0.01% to 10% by weight.
14. A cosmetic formulation according to claim 11 comprising
(a) (−)-guaiol,
(b) further skin-lightening active substance(s) and, optionally,
(c) one or more UV-A and/or UV-B absorbers.
15. A cosmetic formulation according to claim 14 , comprising
(a) from 0.01 to 5% by weight of (−)-guaiol,
(b) from 0.01 to 5% by weight of further skin-lightening active substance(s) and, optionally,
(c) from 0 to 30% by weight of one or more UV-A and/or UV-B absorbers. 3