Phytonutrients affecting hydrophilic and lipophilic antioxidant activities in fruits, vegetables and legumes

The antioxidant activities of fruits (n = 21), vegetables (n = 67) and legumes (n = 7) commonly consumed in Korea were detd. by both the lipophilic antioxidant performance assay (LAP) and the hydrophilic oxygen radical absorbance capacity assay (ORAC). The LAP assay used the lipophilic radical initiator MeO-AMVN [2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile)] and the lipophilic probe BODIPY 581/591 [4,4-difluoro-5-(4-phenyl-1,3-butadienyl)-4-bora-3a, 4a-diaza-s-indacene-3-undecanoic acid]. The ORAC assay used the hydrophilic radical initiator AAPH [2,2'-azobis(2-amidinopropane) dihydrochloride] and the hydrophilic probe fluorescein. In addn., the lipid-sol. phytonutrients, carotenoids and tocopherols were detd. by a reverse-phase HPLC system using a C30 column with a UV detector. The water-sol. phytonutrient, ascorbic acid, was analyzed using an HPLC system with an electrochem. detector. Total phenols were detd. by UV spectrophotometry. Tocopherols (r = 0.774, p < 0.0001) and carotenoids (r = 0.569, p < 0.0001) were significantly correlated with LAP in total samples (n = 95). ORAC was significantly correlated with total phenols (r = 0.893, p < 0.0001), but not with ascorbic acid (r = 0.009, p = 0.929) in total samples (n = 95). These data indicate that carotenoids and tocopherols and total phenols are the major contributors to the lipophilic and hydrophilic antioxidant capacities, resp. Therefore, the contribution of both the hydrophilic and lipophilic components of fruits and vegetables should be considered when detg. the actual 'total' antioxidant activity of fruits and vegetables