Ethnopharmacological communication Anti-cancer activity of compounds from Bauhinia strychnifolia stem Supreeya Yuenyongsawad n , Kingkan Bunluepuech, Chatchai Wattanapiromsakul, Supinya Tewtrakul Department of Pharmacognosy and Pharmaceutical Botany, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand article info Article history: Received 1 March 2013 Received in revised form 4 September 2013 Accepted 7 September 2013 Available online 8 October 2013 Keywords: Anti-cancer activity Bauhinia strychnifolia Fabaceae abstract 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 strychnifolia, 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-α-L-rhamnopyranoside (2) pos- sessed very potent activity against KB (IC 50 ¼0.00054 μg/mL), HT-29 (IC 50 ¼0.00217 μg/mL), MCF-7 (IC 50 ¼0.0585 μg/mL) and HeLa cells (IC 50 ¼0.0692 μg/mL). 3,5,7-Trihydroxychromone-3-O-α-L-rhamno- pyranoside (3) also showed good activity against HT-29 (IC 50 ¼0.02366 μg/mL), KB (IC 50 ¼0.0412 μg/mL) and MCF-7 (IC 50 ¼0.297 μg/mL), respectively. The activity of 2 (IC 50 ¼0.00054 μg/mL) against KB cell was ten times higher than that of the positive control, Camptothecin (anti-cancer drug, IC 50 ¼0.0057 μg/mL). All compounds did not show any cytotoxicity with normal cells at the concentration of 1 μg/mL. Conclusion: This is the first report of compounds 2 and 3 on anti-cancer activity and based on the anti- cancer 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. & 2013 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Cancer is the primary cause of mortality and morbidity in the elderly. Elderly persons are at a ten times greater risk of develop- ing cancer than persons under 65 years of age. Cancer is caused by endogenous and exogenous factors that lead to the sequential accumulation of genetic alterations, a scenario known as multi- step oncogenesis (Lee and Park, 2010). Bauhinia strychnifolia Craib (Fabaceae) is known in Thai as Yanang Dang or Khayan (Larsen and Larsen, 1984). Its climbing stem with tendrils is 5 m long. The leaves are simple, alternate, obovate shape 4–15 cm with 3–5 secondary nerves. The inflorescence is red color with the length of 15–100 cm. The calyx is 1 cm long in cup-shaped. Its ovary is pubescent with the length 0.7 cm. In Thai traditional medicine, the stem and root have been used to treat cancer, fever, alcoholic toxication and allergy (Wutthithammavet, 1997). The leaves or stems in boiling water has been used as a tonic. Mr. Sraupsin Thongnoppakhun, the traditional doctor in Bangkok province, have used Bauhinia strychnifolia stem for treatment of breast and colon cancers by boiling with water. In addition, Dr. Kobkarn Chunhasa- vasdikul, a medical doctor at Oriental Health Bangna Clinic, Bangkok, Thailand, has been used this plant to treat the patients who suffering from colon and stomach cancers by boiling with water. Since an EtOH extract of Bauhinia strychnifolia showed good inhibitory activity against several cancer cell lines without previous reports of its constituents, this study is thus aimed to determine anti-cancer activity of the isolated compounds from this plant in order to obtain the scientific support for its traditional use. 2. Materials and methods 2.1. Reagents Phosphate buffer saline (PBS), penicillin-streptomycin and DMEM were from Invitrogen. 25 cm 3 Flasks and 96-well microplates were from Nunc, fetal bovine serum (FBS) was from Seromed, Tris was from Gibco BRL, Sulforhodamine B (SRB) was from Sigma, trichloroacetic acid (TCA) was from Carlo Erba. The cell lines were from the Cell Lines Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jep Journal of Ethnopharmacology 0378-8741/$ - see front matter & 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jep.2013.09.025 n Corresponding author. Tel.: þ66 74 28 8888; fax: þ66 74 42 8220. E-mail addresses: supreeya.y@psu.ac.th, ysupree@gmail.com (S. Yuenyongsawad). Journal of Ethnopharmacology 150 (2013) 765–769