Swerpunilactones A and B, the first example of xanthone and secoiridoid heterodimers from Swertia punicea, S. hispidicalyx, and S. yunnanensis

Swerpunilactones A (1) and B (2), two novel xanthone and secoiridoid heterodimers, together with their presumed biosynthetic precursors (+/-)-gentiolactone (3), bellidifolin (4), and norbellidifolin (5), were isolated from the whole plants of Swertia species. A plausible biogenetic pathway for swerpunilactones A and B was proposed. In vitro anti-hepatitis B virus assay on the Hep G 2.2.15 cell line showed that both compounds 1 and 2 exhibited activities against the secretion of HBsAg (IC50 = 0.25 and 0.29 mM), HBeAg (IC50 = 0.86 and 0.31 mM), and HBV DNA replication (IC50 = 0.18 and 0.19 mM). (c) 2013 Elsevier Ltd. All rights reserved.