Abstract:Water extracts from 8 kinds of aquatic vegetables were prepared by ultrasonic crushing extraction to evaluate its antioxidant activity.The spectral characteristics of ABTS+free radical reacting with the extracts were investigated.It was found that the peak absorption of ABTS+free radical at 734 nm of 8 kinds of aquatic vegetable extracts showed a dose-effect relationship with the increase the adding of aquatic vegetable dosage after reacting.Compared with the DPPH free radical scavenging test，which was based on the absorption peak measure at 517 nm，the determination of absorption peak of the ABTS+free radical at 734 nm could avoid the spectral interference caused by aquatic vegetable pigments，moreover，the water-soluble characteristics of ABTS+free radicals were more suitable for the evaluation of antioxidant intake in the daily diet.The results showed that the half inhibitory concentrations of 8 aquatic vegetable extracts were as follows：Zizania Latifolia（4.111mg/mL）＞ Sagittaria（2.932mg/mL ＞ EleocharisDulcis（2.517mg/mL）＞ EdibleSeaweed（2.413mg/mL）＞Oenanthe decumbens（1.795 mg/mL）＞ Calliopsis（1.594 mg/mL）＞ Nelumbo Nucifera Geartn（0.974 mg/mL）＞Callipteris Esculenta （0.140 mg/mL）.This showed that free radical scavenging activity of Callipteris Esculenta was the strongest.