Abstract
A new flavonoid, named quercetin 3-O-(2-E-caffeoyl-beta-D-xylopyranosyl)-(1 -> 2)-alpha-L-rhamnopyranosyl-( 1 -> 2)-beta-D-glucopyranoside, was isolated from the methanol extract of Jacquemontia pentantha (Jacq.) (Family Convolvulaceae) aerial part. Its structure was elucidated by spectroscopic analysis including H-1, C-13-NMR, HMQC, HMBC, and ESI-MS. The known flavonoids, quercetin 3-O-beta-xylo-pyranoside, quercetin 3-O-alpha-L- rhamnopyranoside, quercetin-3-O-beta-galacto-pyranoside (hyperin), isorhamnetin 3-O-beta- D-glucopyranoside, kaempferol 3-O-beta-D-glucopyranoside (astragalin), quercetin and kaempferol, were also isolated and characterized. The 70% methanol crud extract and its successive methanol fraction showed significant anti-hyperglycemic activity, antioxidant activity and anti-inflammatory activity. Determination of the median lethal dose (LD50) revealed that 70% methanol total extract was safe. The antimicrobial activity of the extracts was evaluated against Gram positive, Gram negative bacteria, yeast and fungi.