Anti-oxidant activity and total phenolic content of some Asian vegetables

The anti-oxidant activity of extracts from 36 vegetables was evaluated by using a model system consisting of beta-carotene and linoleic acid. The total phenolics of the extracts was determined spectrophotometrically according to the Folin-Ciocalteau procedure and ranged from 34 to 400 mg (100 g)(-1) on a fresh weight basis. Mint, aonla, black carrots, chenopodium, fenugreek, kachnar and ginger had high phenolic contents. The anti-oxidant activity expressed as per percent inhibition of oxidation ranged from a high of 92% in turmeric extracts to a low of 12.8% in long melon. Other vegetables found to have high anti-oxidant activity (>70%) were kachnar, aonla, ginger, fenugreek, mint, beetroot, black carrots, Brussels sprouts, broccoli, lotus stem, yam, coriander and tomato. Antioxidant activity correlated significantly and positively with total phenolics (r(2) = 0.6578, P < 0.05). The results indicate that vegetables containing high phenolics may provide a source of dietary anti-oxidants.