3-O-(E)-p-coumaroyl tormentic acid may be promising lead compound for developing an effective drug for treatment of leukemia, it induces apoptotic cell death in human leukemia (HL60) via mainly mitochondrial pathway by, at least in part, Topo I inhibition. 3-O-trans-p-coumaroyltormenticacid shows cytotoxicity against four human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT-15) in vitro, the IC50 values of 13.72, 14.29,14.61, 14.04 uM, respectively. 3beta-O-cis-p-Coumaroyltormenticacid, and 3beta-O-trans-p-coumaroyltormenticacid are weakly selective for vancomycin-resistant Enterococcus (VRE) compared with eukaryotic cells, with an MIC of 59.4microg mL and a 50% inhibitory concentration (IC50) of 72.0microg mL for monkey kidney epithelial (MA104) cells. A mixture of 3-O-cis-p-coumaroyltormenticacid and 3-O-trans-p-coumaroyltormenticacid shows an inhibitory effect comparable to (-)-epigallocatechin gallate (EGCG) of green tea on the activation of Epstein-Barr virus early antigen (EBV-EA) induced by 12-O-tetradeca--noylphorbol-13-acetate (TPA).