Ochrocephalamines E and F, two new alkaloids from Oxytropis ochrocephala bung

Two new quinolizidine-based alkaloids, ochrocephalamines E (1) and F (2) were isolated from Oxytropis ochrocephala Bunge (Fabaceae). Their structures were elucidated by extensive spectroscopic analysis and electronic circular dichroism (ECD) calculations. Compound 1 represented the first 14-nor matrine with 6/6/6/5 ring system, while compound 2 shared the aloperine-type scaffold including the carbonyl group at C-10 postition. The inhibitory activities of 2 against the secretion of HBsAg and HBeAg were respectively 22.34 ± 4.38% and 18.00 ± 5.01% at the noncytotoxic concentration of 1 × 10-5 mol/L, which were more active than the positive control hyperoside (16.09% and 12.23%). The binding mode between compound 2 and HBV core protein was illustrated by molecular docking.