The aim of this work was to synthesize new pro-vitamins of α-tocopherol (VE) able to release another moiety such as an amino acid, in order to obtain a combined antioxidant and moisturizing effect upon topical application. The new derivatives were characterized and tested for sensitivity to chemical and enzymatic hydrolysis. Lipophilicity was estimated using Log capacity factor and skin retention was determined in vitro, using rabbit ear skin as barrier. Five molecules were synthesized using l-proline, l-serine, l-tyrosine, l-asparagine, and l-citrulline as amino acidic moiety. All pro-vitamins showed similar or lower lipophilicity than α-tocopheryl acetate (VEAc), taken as reference, and similar stability in aqueous solutions. All pro-vitamins showed to be sensitive to enzymatic hydrolysis. None of the pro-vitamins crossed the skin in significant amounts, whereas they accumulated into the skin, in both the dermis and the epidermis. They are more hydrophilic and more water-soluble than the currently used acetate
Synthesis, hydrolysis, and skin retention of amino acid esters of alpha-tocopherol
OSTACOLO, CARMINE;
2009
Abstract
The aim of this work was to synthesize new pro-vitamins of α-tocopherol (VE) able to release another moiety such as an amino acid, in order to obtain a combined antioxidant and moisturizing effect upon topical application. The new derivatives were characterized and tested for sensitivity to chemical and enzymatic hydrolysis. Lipophilicity was estimated using Log capacity factor and skin retention was determined in vitro, using rabbit ear skin as barrier. Five molecules were synthesized using l-proline, l-serine, l-tyrosine, l-asparagine, and l-citrulline as amino acidic moiety. All pro-vitamins showed similar or lower lipophilicity than α-tocopheryl acetate (VEAc), taken as reference, and similar stability in aqueous solutions. All pro-vitamins showed to be sensitive to enzymatic hydrolysis. None of the pro-vitamins crossed the skin in significant amounts, whereas they accumulated into the skin, in both the dermis and the epidermis. They are more hydrophilic and more water-soluble than the currently used acetateI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.