title: Topical beta-carotene is converted to retinyl esters in human skin ex vivo and mouse skin in vivo.
abstract: Human epidermis contains endogenous retinoids (retinol and retinyl esters) and carotenoids (mostly beta-carotene). Previous studies have shown that the enzymes involved in retinoid metabolism are present in human epidermis. There is still a controversy about the presence in the skin of the enzymes able to convert beta-carotene into vitamin A (retinol), although a recent study demonstrated the conversion of beta-carotene into retinol in human cultured epidermal cells. In this study, we addressed the question of the possible bioconversion of topical beta-carotene into vitamin A or derivatives by human and mouse skin. Surgically excised human abdominal skin was mounted on Franz perfusion chambers to assess the cutaneous penetration of topical beta-carotene as well as its metabolism, after a 24-h incubation period, whereas hairless mice received topical beta-carotene 24 h before assaying epidermal beta-carotene and retinoid concentrations. Epidermal retinoid and beta-carotene concentrations were determined by high-pressure liquid chromatography. Topical beta-carotene penetrated well into human and mouse epidermis and induced a 10-fold (human) and a threefold (mouse) increase of epidermal retinyl esters, which demonstrates that topical beta-carotene is converted into retinyl esters by human and mouse epidermis and thus appears as a precursor of epidermal vitamin A.
authors.affiliation: Department of Dermatology, University Hospital, Geneva, Switzerland.
authors.forename: Christophe
authors.initials: C
authors.lastname: Antille
authors.forename: Christian
authors.initials: C
authors.lastname: Tran
authors.forename: Olivier
authors.initials: O
authors.lastname: Sorg
authors.forename: Jean-Hilaire
authors.initials: JH
authors.lastname: Saurat
mesh_terms: D000287:Administration, Topical; D000818:Animals; D015194:Diffusion Chambers, Culture; D004817:Epidermis / Q000187:drug effects* / Q000378:metabolism*; D004952:Esters / Q000378:metabolism; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D008812:Mice, Hairless; D014801:Vitamin A / Q000378:metabolism*; D019207:beta Carotene / Q000493:pharmacokinetics*
chemical_list: D004952:Esters; D019207:beta Carotene; D014801:Vitamin A