Ponicidin and Oridonin Are Responsible for the Antiangiogenic Activity of <i>Rabdosia </i><i>r</i><i>ubescens</i>, a Constituent of the Herbal Supplement PC SPES

Abstract

Antiangiogenic activity has been identified in an aqueous EtOH extract of Rabdosia rubescens, a component of the dietary supplement PC SPES. Bioassay-guided fractionation using a novel in vitro human endothelial cell-based assay for angiogenesis afforded the diterpenoids ponicidin (1) and oridonin (2), with significant antiangiogenic activity at subcytotoxic concentrations, suggesting that these constituents may strongly contribute to the demonstrated clinical efficacy of PC SPES as a treatment for advanced prostate cancer.