Author(s): Ratsimbazafy AM, P Michael, SD Rakotoarivelo, A Ratiarson, CB Lariviere and KK Nkongolo

Abstract: Smilax kraussiana and Anthocleista rhizophoroides are endemic plant species widely distributed in Madagascar and are used as herbal remedies. But their cytotoxicity has never been investigated. We evaluated the cytoxicity of extracts from these species on normal, cervical and skin cancer cell lines. The cell panel analyzed consisted of cervical cancer cell lines (HeLa cells containing the HPV18, SiHa cells carrying the HPV16), Human fibroblast cell (CCL-110), and mouse normal fibroblast cell (NIH3T3). Transformed NIH3T3 carrying oncogenes E6 and E7 were developed. Taxol was used as reference drug. Effects of plant extracts at different dosages and Taxol were analyzed using microscope observations, try pan blue test, and conventional MTT assay. The cytotoxicity activity was inferred by the presence of cell membrane blebbingin the cells treated with plant extracts compared to controls. These characteristics were different from observations made for Taxol that generated trypsinized-like rounded cells. The extracts from S. kraussiana (1.1 mg/kg) and A. rhizophoroides (1.2 mg/kg) exhibited higher cytotoxicity properties on both normal and cancer cell lines from fibroblast and cervix. Their effect was comparable to that of the reference drug Taxol used at low dose. Insertion of E6 and E7 oncogenes in normal fibroblast cells increases their resistance to low dose of plant extracts. All the assays showed dose-dependent responses for the cell lines tested. The extracts in the present study like many others currently used in traditional medicine show general toxicity due to a lack of specificity for cancer cells. This prevents their consideration for clinical trials.