[Constituents and Antioxidant Activity in vitro of Salix microstachya var. bordensis]

To explore the chemical constituents of Salix microstachya var. bordensis and their antioxidant activities.

Column chromatography was used for separation, NMR, UV and MS spectroscopic methods were used for structure identification. Using Vc and BHT as positive controls, free radical scavenging ability of eight components from Salix microstachya var. bordensis was determined by DPPH · method and IC50 of each compound was calculated.

Eight compounds were isolated and identified as kaempferol (1), quercetin-3-o-β-D-glucoside (2), rhamnetin (3), kaemferol-4'-methylether (4), ferulic acid methyl ester (5), myricarin A (6), kaempferol-7,4'-dimethylether (7) and quercetin (8). Scavenging ability of eight compounds had dose-effect relationship with concentration in a certain concentration range; Scavenging ability on DPPH · radical of myricarin A, kaempferol, quercetin and quercetin-3-O-β-D-glucoside were equal, lower to Vc, but slightly stronger than BHT. Others were lower than BHT, and ferulic acid methyl ester was the lowest deriving from the IC50.

Compounds 1-8 are all isolated from Salix microstachya var. bordensis for the first time. Myricarin A, kaempferol, quercetin and quercetin-3-O-β-D-glucoside, having strong antioxidant activities, can be used as effective natural free radical scavenger and have great prospects for development and utilization.