Abstract: The antioxidant activities and inhibition on nitrosation of different solvent extracts from Balanophora harlandii were researched by comparative study.Antioxidant activities of B.harlandii extracts were evaluated by methods of DPPH radical scavenging,ABTS radical scavenging and Prussian blue.Nitrate removal rate and blocking rate of nitrosamine of different solvent extracts were determined with the methods of hydrochloric acid naphthalene ethylene diamine and α-naphthylamine to evaluate its inhibitory effect on nitrosation reactions,respectively.The results showed that the ethyl acetate extract of B.harlandii had the strongest free radical scavenging and ferric icon reducing power (P<0.01),the ABTS free radical scavenging ability of which was higher than Vc (P<0.01).In simulated conditions of human gastric juice (pH 3.0,temperature 37 ℃),B.harlandii extracts can effectively scavenge nitrite and block the nitrosamines synthesis.With the concentration increasing,the rates of scavenging and block trended gently.However,the activity of scavenge nitrite and block the nitrosamines synthesis of B.harlandii  ethyl acetate extract (IC₅₀= 1.91±0.022,8.44±0.091 mg/mL,respectively) were the higher than that of other extracts of B.harlandii.The extracts of B.harlandii had strong antioxidant activity and nitrosation inhibition effect,which had potential value for development and utilization in the antioxidant research and can be most potentially developed as a new anti-cancer natural health product.

Key words: Balanophora harlandii, antioxidant activity, inhibition of nitrosation, free radical, DPPH