A New Flavonol Glycoside from Tristemma hirtum (Melastomataceae)

Chemical investigation of the plant Tristemma hirtum P. Beauv (Melastomataceae) resulted to the isolation of a new flavonol glycoside named quercetin-7-O-${\alpha}$-D-arabinofuranoside (1), together with nine known compounds including 3'-hexadecanoyl-2'-(9aZ)-tetradecanoyl-glycerol 1'-O-[${\beta}$-D-galactopyranosyl-(1'' ${\rightarrow}$ 6'')-${\alpha}$-D-galactopyranoside] (2), arjunolic acid (3), ${\beta}$-sitosterol-3-O-${\beta}$-D-glucopyranoside (4), terminolic acid (5), quercetin (6), asiatic acid (7), maslinic acid (8), $1{\beta}$-O-galloylpedunculagin (9) and 6-hydroxyapigenin 7-O-${\beta}$-D-glucopyranoside (10) from the methanol extract using normal and reversed phase column chromatography. The structures of these compounds were determined by comprehensive interpretation of their spectral data mainly including 1D- 2D-NMR ($^1H-^1H$ COSY, HSQC, and HMBC) spectroscopic and ESI-TOF-MS mass spectrometric analysis.