A new triterpene saponin and known compounds from the polar extract of Salvia argentea L. and evaluation of their antioxidant activity

A new triterpene saponin, 2, 3, 21, 23-tetrahydroxyolean-12-en-2 8-oic-acid-28-O-ss-D- glucosyl-(2' ->.1')-ss-D-glucoside (1), was isolated from the n-butanol extract of dried aerial parts of Salvia argentea L. (Lamiaceae) in addition to two known flavonoids, apigenin 7-O-ss-D-glucoside (2), threo-guaiacylglycerol 3-O-[6-Op-hydroxybenzoyl]-ss-D-glucoside (3), luteolin 7-O-ss-D-glucoside (4), verbascoside (5) and rosmarinic acid (6). The structure elucidation of these compounds was based on analyses of spectroscopic data including 1D-, 2D-NMR and HR-ESI-MS techniques and by comparing their NMR data with those reported in the literature. Compound 6 exhibited the highest antioxidant activity in DPPH assay (IC50<3.00 mu g/mL) which was better than the standards BHA, BHT, Trolox and ascorbic acid. [GRAPHICS] .