Isolation of C-glycosylflavonoids with α-glucosidase inhibitory activity from Passiflora bogotensis Benth by gradient high-speed counter-current chromatography

In this study, we applied a gradient High-Speed Counter-Current Chromatography (HSCCC) method that allowed, by direct injection of an aqueous crude extract of the leaves of Passiflora bogotensis, the successful isolation of six flavonoids in a single run, with purity of each compound higher than 81%. This separation enabled the isolation of two new flavonoid glycosides, apigenin-6-C-alpha-L-rhamnopyranosyl-(1 --> 2)-(6 ''-O-acetyl)-beta-D-glucopyranoside (2) and luteolin-6-C-alpha-L-rhamnopyranosyl-(1 --> 2)-(6 ''-O-acetyl)-beta-D-glucopyranoside (4), and four known ones, isovitexin (1), isoorientin (3), isovitexin-2 ''-O-rhamnoside (5) and isoorientin-2 ''-O-rhamnoside (6). The structures of the isolated compounds were identified by HPLC-DAD, LC-MS, H-1 and C-13 NMR and comparison with literature data. The inhibitory activities of all of these compounds were evaluated in vitro on alpha-glucosidase from S. cerevisiae, and the IC50 was determinate. This is the first study concerning the chemical composition and biological activity of Passiflora bogotensis. (C) 2015 Elsevier B.V. All rights reserved.