Mangiferin attenuates methylmercury induced cytotoxicity against IMR-32, human neuroblastoma cells by the inhibition of oxidative stress and free radical scavenging potential

Mangiferin (MGN), a C-glucosylxanthone was investigated for its ability to protect against methylmercury (MeHg) induced neurotoxicity by employing IMR-32 (human neuroblastoma) cell line. MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and clonogenic cell survival assays confirmed the efficacy of MGN supplementation in attenuating MeHg-induced cytotoxicity. Pre-treatment with MGN significantly (p < 0.01) inhibited MeHg-induced DNA damage (micronuclei, olive tail moment and % tail DNA) thereby demonstrating MGN’s antigenotoxic potential. Also, pre-treatment with MGN significantly reduced MeHg-induced oxidative stress, intra-cellular Ca²⁺ influx and inhibited depolarization of mitochondrial membrane. MGN pre-treated cells demonstrated a significant (p < 0.05) increase in the GSH and GST levels followed by a significant (p < 0.05) decrease in malondialdehyde (MDA) formation. In addition, inhibition of MeHg induced apoptotic cell death by MGN was demonstrated by microscopic, Annexin-V FITC and DNA fragmentation assays and further confirmed by western blot analysis. The present findings indicated the protective effect of MGN against MeHg induced toxicity, which may be attributed to its anti-genotoxic, anti-apoptotic and anti-lipid peroxidative potential plausibly because of its free radical scavenging ability, which reduced the oxidative stress and in turn facilitated the down-regulation of mitochondrial apoptotic signalling pathways.