The present invention relates to compounds having general formula (I): CH3—(CH═CH)n—R  (I) where: n=3, 5, 7; R is chosen from —CH2—O—CO—R′, —CO—OR′ or —CO—O(−), R′ is chosen from H, C1-C22 alkyl or alkenyl, aryl or aralkyl, or sugars; and their pharmaceutically acceptable salts, such as sodium, potassium and lysine salts, for use as the active ingredient in pharmaceutical or cosmetic compositions for improving the pigmentation of the human skin, treating pigmentation disorders and/or improve both the photoprotective capacity of the skin and the intensity of its suntan.