Antioxidant and α-amylase inhibitory compounds from aerial parts of Varthemia iphionoides Boiss

Abstract

Various extracts of aerial parts of Varthemia (Varthemia iphionoides Boiss) were investigated for radical-scavenging activity, antioxidative activity, and porcine pancreas α-amylase inhibitory activity. The ethanol and water extracts showed a pronounced 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, with inhibition of about 90% at a concentration of 100 μg/ml, and α-amylase inhibitory activity of about 70% at a concentration of 200 μg/ml by the 2-chloro-4-nitrophenyl α- maltotrioside (CNP-G3) degradation method. The ethanol extract was purified by column chromatography to give seven 3-methoxyflavones (1-7) and eudesmane sesquiterpene, selina-4,11(13)-dien-3-on-12-oic acid (8). The structures of these compounds were established by NMR, MS, and UV spectroscopy. Of 3-methoxyflavones, 5,7,4′-trihydroxy-3,6-dimethoxyflavone (1), 5,7,4′-trihydroxy-3,3′-dimethoxyflavone (2), and 5,4′-dihydroxy-3,7,3′-trimethoxyflavone (3,7,3′-tri-O-methyl- quercetin) (7) exhibited pronounced radical-scavenging activity. The antioxidative activity in the linoleic acid system was considerable in compounds 1, 2, and 5,4′-dihydroxy-3,6,7-trimethoxyflavone (4). Compounds 1, 2, 4, 5 (5,7,4′-trihydroxy-3-methoxyflavone), and 6 (5,4′-dihydroxy-3,7- dimethoxyflavone) showed markedly high inhibitory activity against porcine pancreas α-amylase. Eudesmane sesquiterpene did not show any activity.