Cytotoxic, Anti-Proliferative and Apoptotic Effects of Tribulus terrestris L. Fruit Extract on Human Prostate Cancer Lncap and Colon Cancer HT-29 Cell Lines

Background: The medicinal herb Tribulus terrestris L. (Zygophyllaceae) has been used for a long time to treat various kinds of diseases including hepatocellular carcinoma. Objectives: The aim of the present study was to investigate the anticancer activity of hydroalcoholic extract of T. terrestris fruit on prostate and colon cancerous cell lines. Materials and Methods: The activity of the extract was studied at seven different concentrations on three cell lines, human colon adenocarcinoma (HT29), prostate carcinoma (LNCap-FGC-10) and fibroblast-like cells (HSkMC). MTT, bromo-2’-deoxyuridine(BrdU) and terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) assays were used for measuring cytotoxicity, cell proliferation and apoptotic cell death, respectively. Results: The IC50 index of the extract of T. terrestris was obtained as 0.3 g/mL, 7.1 g/mL and 8.7 g/mL for prostate, colon and fibroblast-like cell lines, respectively. Tribulus terrestris L. was significantly more toxic on prostate cancer cell line than on colon cancer cell and fibroblast-like cells (P value < 1%). Quantitating BrdU incorporation at the highest concentration was determined as 0.097 and 0.018. Furthermore, the extract induced 74% and 46% apoptosis in prostate and colon cancer cells, respectively. Conclusions: These data indicate that T. terrestris extract has cytotoxic, anti-proliferative and pro-apoptotic activities. It was less toxic against normal human fibroblast-like cells in comparison to cancer cell lines. Further in vivo research would help explore and interpret the potential properties of T. terrestris extract and its components as an anticancer supplement.