The invention relates to a cosmetic and/or pharmaceutical composition comprising, in a physiologically suitable medium, a carob peptide extract (Ceratonia siliqua L.) as an active agent for promoting aquaporin expression. The present invention also relates to the use of a carob peptide extract (Ceratonia siliqua L.), as an active agent for promoting aquaporin expression, in a cosmetic composition for improving the moisturization and the barrier function of the epidermis and for stimulating skin regeneration. The invention also relates to the use of this novel active agent for preparing a pharmaceutical, in particular dermatological, composition for regulating and/or stimulating aquaporin activity. The invention also relates to a cosmetic treatment method for preventing or combating dryness of the skin and mucous membranes and the manifestations of skin aging.