In vitro cytotoxicity study of Melastoma malabathricum Linn. : the effects toward MMP-13 expression and apoptosis

Abstract

The search for natural anticancer remedies is one of the most prominent research in the cancer treatments. For that purpose, various plants from all over the world have been studied. The researchers are now more focusing to understand the mechanisms involved in the cancer treatment using the natural sources. Melastoma malabathricum Linn is known as a shrub that wildly grows in the tropical and subtropical regions. A number of studies have been conducted on this plant, but the reports on its anticancer properties are still limited. The main objective of this study is to study the effects of M. malabathricum extracts from different parts at various concentrations on three types of cancer cell lines in vitro (A375, HeLa and MCF-7) and its relation to the apoptosis mechanism and the expression of the target protein, MMP-13 in the treated cells. Liquid-liquid extraction protocol using methanol, petroleum ether and chloroform as the solvent systems were carried out on leaves, stems and flowers of M. malabathricum. Dimethyl sulfoxide, DMSO (1 %) was used in the extract dilution and serial dilutions were conducted to obtain eight different extract concentration, ranging from 0.078125 µg/mL to 10 µg/mL. The evaluation of cancer cells growth inhibition for 24, 48 and 72 hours of treatment was determined using MTT assay. The treated cancer cells were then tested for morphological apoptosis detection through TUNEL assay and detection of MMP-13 expression using Western Blot analysis. The result showed that petroleum ether extracts of stems (PeMMS) and leaves (PeMML) have the best growth inhibitory effects on A375 (EC50 = 0.185 µg/mL at 48 hours) and HeLa cell lines (EC50 = 0.368 µg/mL at 48 hours). The chosen extracts were also confirmed do not cause toxicity effect on normal human fibroblast cell lines (CCD-1090Sk). Further analysis revealed that PeMMS and PeMML caused a high percentage of apoptotic cells, around 26 % in A375 and HeLa cells respectively. The apoptosis results are comparable or in approximate with the percentage of apoptosis induced by commercialized anticancer drug, paclitaxel (26.4 %). Western blot analysis showed the reduction of MMP-13 expression in the A375 and HeLa cells treated with PeMMS and PeMML, respectively. Based from the outcomes, this study suggests that the reduced expression of MMP-13 correlates with the increasing level of apoptosis in the cells treated with PeMMS and PeMML. In conclusion, the petroleum ether extract of stems and leaves of M. malabathricum showed a promising anticancer properties toward skin melanoma and cervical cancer cell lines. Further investigation needs to be conducted in order to assess the probable bioactive compounds in the petroleum ether extract of M. malabathricum that may contribute to the significance cytotoxic effects to the respective cell lines.