Four new diterpenoids from the twigs and leaves of Phyllanthus acidus

Abstract

Abstract Four new ent-cleistanthane type diterpenoids, phyacioids A–D (1–4), along with two known analogues (5 and 6) were isolated from the powered twigs and leaves of Phyllanthus acidus. Compound 1 was characterized as the third reported structure that possesses a 4,5-seco-20(10\xa0→\xa05)-abeo-(ent)-cleistanthane scaffold, and compounds 2 and 3 feature a rare alkynyl group. The structures of 1–4 were assigned by spectroscopic data, with their absolute structures being determined through electric circular dichroism (ECD) calculations. Compounds 3, 5 and 6 showed moderate cytotoxicity with IC50 values ranging from 13.8 to 36.0\xa0μM.