Toxic effects of fluoride in intestinal epithelial cells and the mitigating effect of methanol extract of coconut haustorium by enhancing de novo glutathione biosynthesis

Abstract

Fluoride ions are an important environmental contaminant and pollutant found in a wide variety of environmental conditions. The fluoride in drinking water is evident to induce toxic effects including neurodegeneration, skeletal and dental fluorosis as well as organ damage. Nutraceuticals and functional foods are emerging as possible preventive agents against fluoride toxicity. Hence, the possible use of an emerging functional food-the coconut haustorium is being evaluated against sodium fluoride-induced toxicity in intestinal cells (IEC-6). The cells exposed to fluoride showed significant cell death mediated through the increased lipid peroxidation and glutathione depletion. The glutathione biosynthetic enzymes were inhibited by the exposure to fluoride and the apoptotic genes (caspases 3/7 and apaf-1) were upregulated. The CHE pre-treatment improved the activity of enzymes involved in the de novo biosynthesis of glutathione and subsequently improved the intracellular GSH pool. The improved antioxidant defense was also evident from the reduced expression of apoptotic genes (p < 0.05). Overall, the study concludes that fluoride ions induce oxidative stress-mediated apoptosis in intestinal epithelial cells, via inhibiting glutathione biosynthesis. Methanol extract of coconut haustorium increased glutathione biosynthesis and subsequently prevented fluoride toxicity in IEC-6 cells by virtue of its antioxidant potentials.