Protective Role of Mentha arvensis Aqueous Extract against Manganese Induced Toxicity by Reducing Mn Translocation and Promoting Antioxidative Defense in growing Indica Rice Seedlings

Abstract

Mentha arvensis L. (Ma) leaf extract, a wide source of natural antioxidants is widely used to protect animal cells against oxidative stress. In the current study, we have studied the ameliorative effects of Ma leaf extract on Mn induced oxidative stress in rice (Oryza sativa L.) seedlings. Hydroponically grown rice seedlings treated with 1.5 mM MnCl2 showed a decline in vigour and contents of photosynthetic pigments, increased production of reactive oxygen species (O2˙‾, H2O2, and.OH), lipid peroxidation, protein thiol and carbonyl contents along with increased activity of antioxidative enzymes- superoxide dismutase (SOD), guaiacol peroxidase (GPX) and ascorbate peroxidase (APX). The activity of catalase (CAT), however, declined in the seedlings after prolonged Mn treatment of 8 days. Interestingly exogenous application of Ma leaf extract (638.4 mg ml-1) effectively restored the Mn-induced decline in seedling vigour, photosynthetic pigments, increased levels of H2O2, lipid peroxides and altered activities of antioxidative enzymes. The results indicate that exogenous application of Ma leaf extract significantly lowers the toxic effects of Mn in rice seedlings by modulating Mn translocation and reducing oxidative stress.