First isolation of tryptophan from edible lotus (Nelumbo nucifera Gaertn) rhizomes and demonstration of its antioxidant effects.

摘要

Various vegetables were investigated for antioxidative activity in 2 assays (inhibition of lysis of erythrocytes induced by peroxyl radicals and inhibition of lipid peroxidation). Lotus roots showed the strongest antioxidative activity in both assays. The crude extract of lotus root (L) was chromatographed on a macroporous adsorption resin. The resulting 3 fractions were designated L1, L2 and L3, respectively. L2 showed the highest antioxidative activity and was further fractionated by Sephadex LH-20 chromatography. 8 fractions were obtained and named from L2a to L2h, respectively. L2c showed the strongest activity in inhibiting haemolysis of erythrocytes and was further purified by HPLC. L2c-3 was identified as tryptophan. Its inhibitory concn. of 50% value in inhibiting haemolysis of erythrocytes was 156.3 mug/ml (i.e. 765.4 muM).