Protection of Antioxidants, Vitamins E and C, from Ultraviolet Degradation using Feruloylated Vegetable Oil

Abstract

AbstractNatural antioxidants are often used in topical personal care formulations to protect the skin from oxidative stresses but are susceptible to degradation due to ultraviolet (UV) radiation. Feruloyl soy glycerols (FSG) are UV absorbers synthesized from the biocatalytic conversion of soybean oil and ferulic acid ethyl ester that have a total UV absorbance and photostability comparable to the commercial UV absorber, 2‐ethylhexyl‐4‐methoxycinnamate (octinoxate, ONX). We examined the ability of FSG and ONX to photoprotect the antioxidant capacity of Vitamin E (VE), Vitamin C (VC), Vitamin E, and their derivatives, 6‐hydroxy‐2,5,7,8‐tetramethylchroman‐2‐carboxylic acid (Trolox, TLX) and L‐ascorbic acid 6‐palmitate (Vitamin C palmitate, VCP), from UV degradation. VE, VC, TLX, and VCP (100 μM solutions) acted as rapid antioxidants, scavenging >50% of the spontaneously formed free radical, 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH*, 200 μM), within 5 min in acetonitrile solutions. The vitamins and TLX were rendered slow antioxidants in the DDPH* assays, scavenging <50% of DPPH* within 30 min, after exposure of the acetonitrile solutions to UV radiation for 4 hours. VCP solutions were rendered moderate antioxidants, scavenging >50% of DPPH* within 30 min, after 4 hours exposure to UV radiation. FSG (100–1000 μM) was added to acetonitrile solutions of the vitamins and their derivatives to determine if FSG could photoprotect VE, TLX, VC, and VCP, allowing them to retain their antioxidant activities after 4 hours of UV irradiation. The addition of FSG, 500 and 1000 μM, allowed TLX and VE to retain rapid antioxidant activity after 4‐hour UV exposure. VC retained rapid antioxidant capacity with 100 μM FSG after 4 hours of UV exposure. FSG performed comparably to slightly better than the commercial UV absorber, ONX, in protecting the antioxidant activities of vitamins and their derivatives from UV degradation. FSG also possessed intrinsic antioxidant capacity that ONX did not, which may have contributed to its better performance when mixed with the vitamins and their derivatives in the DPPH* assays.