Novel apo-tirucallane triterpenoids from Walsura trifoliata

Two structurally interesting novel apo-tirucallane triterpenoids, piscidinone A and B were isolated from the leaves and twigs of Walsura trifoliata and their structures were elucidated on the basis of spectroscopic data, mainly NMR and MS data, respectively. These novel secondary metabolites have tetracyclic ring and a new type of substituted pyran ring as a side chain, and their biosynthetic origin was proposed to be the apo-tirucallane triterpenoids. Further, compounds 1 and 2 were also evaluated for their cytotoxicity against cancer cell lines (HT-29, MCF-7, Hela, A-549, B-16, IEC-6, L-6 and PC-3), which displayed moderate activities against tested cell lines with the IC50 values ranging from 14.33 to 50.63 μg/mL, respectively.