Synthesis and Cytotoxicity on Human Lung Cancer Cell Lines of 2-Arylidene and Related Analogues of Malabaricol

[Image: see text] Malabaricol is a unique plant natural product, 3-keto tricarbocyclic triterpenoid, isolated from Ailanthus malabarica. Malabaricol underwent reaction with aromatic aldehydes under alkaline conditions to form 2-arylidene analogs. Indoles and pyrazine ring system fused to the 2,3-position of malabaricol were synthesized. In this ring system of tricarbocyclic triterpenoid, the conformation is such that there is no steric hindrance due to C(4) and C(10) axial methyl groups and other skeletons. Malabaricol and its synthetic analogues show cytotoxic activity toward lung cancer, which was compared to that of standard doxorubicin.