Harmonization of Mangiferin on methylmercury engendered mitochondrial dysfunction

Mangiferin (MGN), a C-glucosylxanthone abundantly found in mango plants, was studied for its potential to ameliorate methylmercury (MeHg) induced mitochondrial damage in HepG2 (human hepatocarcinoma) cell line. Cell viability experiments performed using 3-[4,5-dimethylthiazol-2-yl]-2,5- diphenyltetrazolium bromide (MTT) showed protective property of MGN in annulling MeHg-induced cytotoxicity. Conditioning the cells with optimal dose of MGN (50 µM) lowered MeHg-induced oxidative stress, calcium influx/efflux, depletion of mitochondrial trans-membrane potential and prevented mitochondrial fission as observed by decrease in Mitotracker red fluorescence, expression of pDRP1 (serine 616), and DRP1 levels. MGN pre-treated cells demonstrated elevation in the activities of glutathione (GSH), Glutathione-S-transferase (GST), Glutathione peroxidase (GPx), Glutathione reductase (GR), reduced levels of Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT) and mitochondrial electron transport chain (ETC) enzyme complexes. In addition, the anti-apoptotic effect of MGN was clearly indicated by the reduction in MeHg-induced apoptotic cells analyzed by flowcytometric analysis after Annexin V-FITC/propidium iodide staining. In conclusion, the present work demonstrates the ability of a dietary polyphenol, MGN to ameliorate MeHg-mediated mitochondrial dysfunction in human hepatic cells in vitro. This hepatoprotective potential may be attributed predominantly to the free radical scavenging/antioxidant property of MGN, by facilitating the balancing of cellular Ca²⁺ ions, maintenance of redox homeostasis and intracellular antioxidant activities, ultimately preserving the mitochondrial function and cell viability after MeHg intoxication. As MeHg intoxication occurs over a period of time, continuous consumption of such dietary compounds may prove to be very useful in promoting human health.