Quassinoids from the Root Barks of Ailanthus altissima:Isolation,Configurational Assignment,and Cytotoxic Activities

Main observation and conclusion Quassinoids,a class of highly oxygenated triterpenes,have been isolated as bitter principles from the plants of Simaroubaceae family.Five new quassinoids,chouchunlactone A-E(1-5),and two known ones were identified from the root barks of Ailanthus altissima Swingle(Simaroubaceae).The chemical structures of the new compounds were deduced by spectroscopic data analyses,NMR calculations and DP4+probability analysis.The absolute configurations were defined by comparison of their experimental and calculated electronic circular dichroism(ECD)spectra data,and compounds 1-2 were further confirmed by single-crystal X-ray diffraction.Biologically,compound 5 showed potencies equivalent to sorafenib(IC50 value,9.70μmol·L–1)against HepG2 cells.The Hoechst 33342 staining,JC-1 fluorescent dye and Annexin V/PI analysis studies demonstrated that 5 can induce apoptosis and attenuate mitochondrial membrane potential(MMP)in HepG2 cells.