Antiproliferative activity of Hoslundia opposita leaf extract and fractions against a human glioblastoma cell line (U251)

BACKGROUND: The ineffectiveness of many known anticancer agents for treating several cancer types, especially glioblastoma (GMB), which affects the body's central nervous system, is highly important. GBM is highly invasive and recalcitrant and accountsfor 42% of all central nervous system tumors and 60% of all brain tumors in adults, with a median survival of 15 months. The limitationsencountered in GBM treatment necessitate the discovery and development of new drugs. METHODS: To investigate the anticancer activity of Hoslundia opposita leaf extracts and fractions against a human glioblastoma cell line (U251) and human keratinocyte HACAT cell line, standard methods, MTT, clonogenic and caspase3 and 7 assays were used to determine the viability of the cells and colony formation and apoptotic activities, respectively. The fluorescent probe dyes dihydrofluorescindiacetate (DCFH-DA) and tetramethylrhodamine (TMRE) were used to determinethe intracellular reactive oxygen species (ROS) concentration and mitochondrial membrane potential (MMP), respectively, in the cells. RESULTS: The crudemethanolic extracts and fractions of H. opposita leaves exhibited moderate cytotoxic and selective activity within the range of concentrations tested (25-100 µg/ml). The study revealed that crude AHO1 and specific fractions of AHO5 and AHO6 inhibitedmetastasis or colony formation, promoted apoptosis in the U251 cell line and depolarized the mitochondrial membrane potential, which was likelymediated by mitochondria-dependent ROS generation. Overall, the specificity and dose dependenceof the different treatments were observed for the U251 cell line. Conclusions: The antiproliferative activities of Hoslundia opposita Vahl demonstrated by the crude extract and specific fractions against U251 cells warrant further investigations todecipher its mechanism of action.