Dhasingreoside: new flavonoid from the stems and leaves of Gaultheria fragrantissima.

A new flavonoid, dhasingreoside (1) and seven known compounds, quercetin 3-O-β-D-galacturonopyranoside (2), quercetin 3-O-β-D-galactopyranoside (3), quercetin 3-O-β-D-glucuronopyranoside (4), quercetin 3-O-α-L-rhamnopyranoside (5), (-)-epicatechin (6), salicylic acid (7) and gaultherin (8), have been isolated from the shade-dried stems and leaves of Gaultheria fragrantissima, commonly known as 'Dhasingre' in Nepal. The structures were elucidated on the basis of physical, chemical and spectroscopic methods. Among known compounds, five compounds (3-6 and 8) were isolated for the first time from G. fragrantissima. In vitro antioxidant activity of all the isolated compounds was evaluated by 1,1-diphenyl-2-picrylhydrazyl free radical-scavenging assay. Dhasingreoside (1) and other compounds (2-6) showed significant free radical-scavenging activity.