Cytotoxic Lignans from Fruits of Cleistanthus indochinensis: Synthesis of Cleistantoxin Derivatives

Two new aryl-tetralin lignans, 1 and 2, were isolated from the fruits of Cleistanthus indochinensis by bioassay-guided purification. Their structures were determined by spectroscopic analysis including MS and 2D NMR. The absolute configurations of 1 and 2 were established from examination of their CD spectra. Compound 1 was cytotoxic against KB cells with an IC(50) value of 0.022 μM, while compound 2 had weaker cytotoxicity, with an IC(50) value...