Abstract: Methods for reducing pigmentation or hyperpigmentation of skin comprising applying to the skin a substance of formula (I) in the D-form, L-form or racemic form (D,L) are disclosed: wherein R1 is selected from the group consisting of a hydrogen group (—H), a methyl group (—CH3), an ethyl group (—CH2CH3), a C3 alkyl group, a C4 alkyl group, an acetyl group (—C(O)CH3), a propanoyl group (—C(O)CH2CH3), an n-butanoyl group (—C(O)CH2CH2CH3), and a 2-methyl-propanoyl group (—C(O)CH(CH3)2), R2 is selected from the group consisting of a hydrogen group (—H), an ethyl group (CH2CH3), a C3 alkyl group, a C4 alkyl group, an acetyl group (—C(O)CH3), a propanoyl group (—C(O)CH2CH3), an n-butanoyl group (—C(O)CH2CH2CH3), and a 2-methyl-propanoyl group (—C(O)CH(CH3)2), R3 is selected from the group consisting of a hydroxyl group (—OH), an amino group (NH2), a methoxy group (OCH3), an ethoxy group (—OCH2CH3), a C3 alkoxy group, a C4 alkoxy group, and a benzyloxy group (—OCH2C6H5), and X and Y are independently selected