The role of glutathione in dichloromethane toxicity to Lemna paucicostata

Abstract

Growth rate of Lemna paucicostata was significantly decreased by dichloromethane treatment; exhibiting IC25, IC50, and IC75 values of 4.73 g/L, 74.72 g/L, and 124.18 g/L, respectively. At the IC25 concentration, an increase in ascorbate content and a concomitant decrease in lipid peroxidation level were exhibited, indicating an adaptive induction of ascorbate synthesis to protect membrane in response to oxidative stress caused by low level of dichloromethane. At the concentrations higher than IC50, dichloromethane caused significant increases in reactive oxygen species formation and lipid peroxidation and caused simultaneous decrease in glutathione (GSH) and ascorbate contents, implying the treatment-induced oxidative damage. Our results demonstrated that dichloromethane caused a decrease in glutathione reductase to glutathione peroxidase activity ratio, which disabled recycling of GSH and led to a depletion of glutathione pool. This suggests that the decline of glutathione redox cycling may play a crucial role in dichloromethane-induced oxidative damage and toxicity to L. paucicostata.