The present invention concerns a peptidic hydrolyzate enriched in bioactive peptides, said hydrolyzate being a proteasome activator. Further, the present invention concerns a cosmetic or pharmaceutical composition comprising said hydrolyzate in a physiologically acceptable medium and also its use in treating signs of aging or photo-aging in skin and protecting the skin against challenges by ultraviolet radiation. Finally, the invention concerns a cosmetic treatment method intended to treat the signs of skin aging and photo-aging.