An unusual [Formula: see text] linked flavonoid from Miconia cabucu (Melastomataceae)

摘要

Chromatographic fractionation of the methanolic extract from the leaves of Miconia cabucu Hoehne (Melastomataceae) afforded the first example of a [Formula: see text] linked flavone dimer, 5-hydroxy-4',7-dimethoxyflavone-(6-C-6'')-5''-hydroxy-3''',4''',7''-trimet hoxyflavone as well as the known compounds, quercetin-3-O-alpha-l-rhamnopyranosyl-(2-->1)-O-beta-d-xylopyranoside, quercetin-3-O-alpha-l-rhamnopyranoside, myricetin-3-O-alpha-l-rhamnopyranoside, quercetin-3-O-beta-d-glucopyranoside, kaempferol-3-O-beta-d-(6''-coumaroyl)-glucopyranoside and gallic acid. Their chemical identities were established by application of NMR spectroscopic methods including 2D-NMR, as well as UV and ESI-MS analyses.