The present invention relates to novel heterocyclic derivatives of 2-oxothiazolidine-4-carboxylic acid, to a process for synthesizing them and to compositions containing them. The invention also relates to the use of at least one heterocyclic derivative of 2-oxathiazolidine-4-carboxylic acid in a composition or for the manufacture of a composition, the said derivative or the said composition being intended to induce active photoprotection of the skin, advantageously to prepare the skin to receive sunlight and/or to protect the skin and other epidermal growths during or after exposure to UV. Another subject of the invention also relates to a cosmetic process for treating the skin by oral administration or topical administration to the skin of a cosmetic composition as defined above.