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-α-l-rhamnopyranosyl-(1→2)-(6″-O-acetyl)-β-d-glucopyranoside (2) and luteolin-6-C-α-l-rhamnopyranosyl-(1→2)-(6″-O-acetyl)-β-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, ¹H and ¹³C NMR and comparison with literature data. The inhibitory activities of all of these compounds were evaluated in vitro on α-glucosidase from S. cerevisiae, and the IC₅₀ was determinate. This is the first study concerning the chemical composition and biological activity of Passiflora bogotensis.