Cosmetic use, as an agent to prevent and / or treat an aesthetic defect of the skin and / or its appendages that is related to an imbalance in the differentiation and / or proliferation of the cells of an epidermis, of an effective amount of at least one a compound represented by the general formulas (Ia) or (Ib): ** ** Formula wherein: - R1 represents H； -C (O) R10, R10 being a C1-C4 alkyl saturated or unsaturated, linear or branched, or being phenyl； - R2 represents H； a saturated or unsaturated, linear or branched C1-C12 alkyl group； or a group selected from: ** ** Formula wherein R5, R6, R7, R8 and R9 represent, independently of one another, H； -NO2； -OH； OR10； -CN； a fluorine； Cl； I； Br； -CF3 a saturated or unsaturated, linear or branched C1-C4 alkyl； a phenyl； -OC (O) -R10； -O-Ph-X with X representing H, -OH, -NO2, a fluorine, a saturated or unsaturated, linear or branched C1-C4 alkyl or alkyl； with R10 being as defined above, - R3 represents a group -OR11, with R11 being H, a saturated or unsaturated, linear or branched C1-C4 alkyl, or a phenyl, - R4 represents a saturated C1-C4 alkyl or unsaturated, linear or branched； or a phenyl, - R and R ', which are identical or different, represent H or a C1-C4 linear or branched alkyl, or a physiologically acceptable salt of said compound.Uso cosmético, como agente para prevenir y/o tratar un defecto estético de la piel y/o sus apéndices que está relacionado con un desequilibrio en la diferenciación y/o proliferación de las células de una epidermis, de una cantidad eficaz de al menos un compuesto representado por una de las fórmulas generales, (Ia) o (Ib):**Fórmula** donde: - R1 representa H； -C(O)R10, con R10 siendo un alquilo C1-C4 saturado o insaturado, lineal o ramificado, o siendo un fenilo； - R2 representa H； un grupo alquilo C1-C12 saturado o insaturado, lineal o ramificado； o un grupo seleccionado de:**Fórmula** donde R5, R6, R7, R8 y R9 representan, independientemente uno de otro, H； -NO2； -OH； OR10； -CN； un
