Englerin A, a Selective Inhibitor of Renal Cancer Cell Growth, from Phyllanthus engleri

An extract from Phyllanthus engleri was identified in a bioinformatic analysis of NCI 60-cell natural product extract screening data that selectively Inhibited the growth of renal cancer cell lines. Bioassay-guided fractionation yielded two new gualane sesquiterpenes, englerins A (1) and B (2). Englerin A showed 1000-fold selectivity against six of eight renal cancer cell lines with GI(50) values ranging from 1-87 nM. The structures of I and 2 and their relative stereochemistry were established by spectroscopic methods,