A new stigmasterol glucoside from aerial parts of Ecliptae Herba / 中草药

ABSTRACT

Objective: To investigate the bioactive chemical constituents of the aerial parts of Eclipta prostrata. Methods: The compounds were isolated and purified by macroporous absorption resin, silica gel, Sephadex LH-20 and semi-preparative HPLC chromatography. Their structures were determined by MS and NMR data. The α-glucosidase inhibitory activities of compounds 1 and 2 were tested by in vitro screening assay. Results: A total of eight compounds were isolated from the ethyl acetate partition of the ethanol extract of E. prostrata. They were identified as 7β-hydroxystigmasterol 3-O-β-D-glucopyranoside (1), 7α-hydroxystigmasterol 3-O-β-D-glucopyranoside (2), 7α-hydroxysitosterol 3-O-β-D-glucopyranoside (3), 3β,23-dihydroxy-30-norolean-12,20 (29)-dien-28- oic acid (4), camellenodiol (5), echinocystic acid-3-O-(6-O-acetyl)-β-D-glucopyranoside (6), eclalbasaponin I (7) and eclalbasaponin IV (8). Compound 2 exhibited strong inhibition against α-glucosidase with an IC50 value of (11.7 ± 4.2) μmol/L. Conclusion: Compound 1 is a new compound named eclalbasaponin XIV and compounds 3-5 are reported from this herb for the first time. Steroidal glycosides could be the anti-hyperglycaemic components in E. prostrata by inhibiting α-glucosidase.