Syntheses of Novel Hybrid Vitamin C Derivatives: Stability and Biological Activity

A novel series of hybrid L-ascorbic acid (vitamin C) derivatives linking other biologically active substances glycolic acid, myo-inositol, and α-tocopherol (vitamin E) at the C-2 or C-3 hydroxyl group were synthesized, and their thermal stability and inhibitory activities against tyrosinase-catalyzed melanin formation, active oxygen species (AOS), and free radicals were evaluated in vitro. Among these derivatives, 2-O-carboxymethylascorbic acid had high thermal stability as well as moderate inhibitory activities against tyrosinase-catalyzed melanin formation, AOS, and free radicals compared to other typical inhibitors and scavengers. On the other hand, 3-O-carboxymethylascorbic acid was markedly unstable in aqueous solution. The 2-O-carbonylmethyl derivatives linking myo-inositol or vitamin E were susceptible to degrading, however the vitamin E derivative had stronger inhibitory activities against AOS and free radicals than free vitamin C.