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

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 C₄ and C₁₀ 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.