Anti-cancer activity of compounds from Bauhinia strychnifolia stem

Ethnopharmacological relevance: The stem and root of Bauhinia strychnifolia Craib (Fabaceae family) have been traditionally used in Thailand to treat fever, alcoholic toxication, allergy and cancer. An EtOH extract of Bauhinia strychnifolia showed good inhibitory activity against several cancer cell lines including HT-29, HeLa, MCF-7 and KB. As there has been no previous reports on chemical constituents of Bauhinia stiychnifolia, this study is aimed to isolate the pure compounds with anti-cancer activity. Materials and methods: Five pure compounds were isolated from EtOH extract of Bauhinia strychnifolia stem using silica gel, dianion HP-20 and sephadex LH-20 column chromatography and were tested for their cytotoxic effects against HT-29, HeLa, MCF-7 and KB cell lines using the Sulforhodamine B (SRB) assay. Results: Among five compounds, 3,5,7,3',5'-pentahydroxyflavanonol-3-O-alpha-L-rhamnopyranoside (2) possessed very potent activity against KB (IC50=0.00054 mu g/mL), HT-29 (IC50=0.00217 mu g/mL), MCF-7 (IC50=0.0585 mu g/mL) and HeLa cells (IC50=0.0692 mu g/mL). 3,5,7-Trihydroxychromone-3-O-alpha-L-rhamnopyranoside (3) also showed good activity against HT-29 (IC50=0.02366 mu g/mL),KB (IC50=0.0412 mu g/mL) and MCF-7 (IC50=0.297 mu g/mL), respectively. The activity of 2 (IC50=0.00054 mu g/mL) against KB cell was ten times higher than that of the positive control, Camptothecin (anti-cancer drug, IC50=0.0057 mu g/mL). All compounds did not show any cytotoxicity with normal cells at the concentration of 1 mu g/mL. Conclusion: This is the first report of compounds 2 and 3 on anti-cancer activity and based on the anticancer activity of extracts and pure compounds isolated from Bauhinia strychnifolia stem, it might be suggested that this plant could be useful for treatment of cancer. (C) 2013 Elsevier Ireland Ltd. All rights reserved.