New tirucallane triterpenoids from Picrasma quassioides with their potential antiproliferative activities on hepatoma cells.

Graphical abstract Highlights • Seven new tirucallane triterpenoids were isolated from Picrasma quassioides. • Compound 1 contains a rare Δ17, 20 double bond. • Compound 2 possessing a novel 5/3 biheterocyclic ring system at the side chain. • All 27 isolates were screened for the cytotoxicity against HepG2 and Hep3B cells. • Compound 3 mediated its activity associated with induce apoptosis of HepG2 cells. Abstract Seven new tirucallane-type triterpenoids (1 – 7), kumuquassin A-G, along with 20 known analogues (8 – 27) were isolated from the stems of Picrasma quassioides. The structures and the absolute configurations of new compounds were elucidated by spectroscopic data, electronic circular dichroism (ECD) spectroscopic analyses and quantum ECD calculations. Notably, kumuquassin A (1) contains a rare Δ17, 20 double bond, kumuquassin B (2) is the first example of tirucallane triterpenoid possessing a 5/3 biheterocyclic ring system at the side chain. All the compounds were screened for the cytotoxicity against two human hepatoma cell lines, HepG2 and Hep3B, and several compounds exhibited promising activity. The most potential compound 3 was selected for cell cycle analysis, which showed that 3 could cause an accumulation of HepG2 cells at subG1 peak. Annexin V-FITC/PI staining further confirmed that compound 3 caused death of hepatoma cells through apoptosis induction. [ABSTRACT FROM AUTHOR]