The in vitro cytotoxic activity of ethno-pharmacological important plants of Darjeeling district of West Bengal against different human cancer cell lines

BACKGROUND Plant derived components have attracted particular attention as an alternative source to battle several diseases including cancer. The variation in the climate, the geographical location and the rich ethnomedicinal traditions has made the Darjeeling Himalayas an abode of invaluable repository of traditional medicinal plants. In this study, we explored the in vitro anticancer properties of traditionally used medicinal plants from the Darjeeling hills against different human cancer cell lines. METHODS The ethanolic leaf extracts of 30 medicinal plants were tested for their cytotoxicity against human breast adenocarcinoma cell line (MCF 7), human hepatocarcinoma cell line (HepG2) and human cervix adenocarcinoma cell line (HeLa). The cytotoxicity was evaluated by performing MTT assay, trypan blue exclusion assay and morphological assessment under phase contrast inverted microscope. For the extracts which tested positive, IC50 (the concentration that inhibited cell growth by 50%) was calculated. The extract(s) were further subjected to Thin Layer Chromatography (TLC) to determine their phytochemical profile. RESULTS Out of the 30 plant extracts tested, five plants, Artemisia indica, Eupatorium odoratum, Eupatorium adenophorum, Maesa macrophylla and Phlogacanthus thyrsiformis showed a > 50% growth inhibition of cancer cell lines at a concentration of 50 μg/ml. The sensitivity to different extracts varied according to the cell type under investigation. Of these plants, Maesa macrophylla, exhibited the most potent cytotoxicity against HeLa and MCF7 cell with IC50 values of 9.55 μg/ml and 16.19 μg/ml respectively. Phytochemical analysis revealed the presence of coumarins, flavonoids, tannins, saponins, steroids and terpenes. CONCLUSIONS This is perhaps the first report of screening of traditional medicinal plants from Darjeeling district in West Bengal, India, for their cytotoxic activity against three human cancerous cell lines MCF7, HeLa and HepG2. The extracts of Maesa macrophylla significantly inhibited the growth of HeLa and MCF7 cancerous cell lines and constituted of multiple known biologically active compounds. The present study may provide the landmark for further exploration of M. macrophylla for its potent anticancer constituents.