Alterations in the glutathione-redox balance induced by the bio-insecticide Spinosad in CHO-K1 and Vero cells.

The biopesticide Spinosad causes a drop in cell viability in two mammalian cellular models CHO-K1 and Vero, using the neutral red incorporation assay as endpoint. Dose-response curves were assessed after 24, 48, and 72 h under different conditions i.e. presence of 10% fetal calf serum or 1% bovine serum albumin or antioxidants. The presence of antioxidant agents, viz. reduced glutathione (1 mM), vitamin C (100 microM), and vitamin E (20 microM) reduced significantly the cytotoxic effect of Spinosad, thus pointing to an oxidative damage mediated by this compound. An increase in malondialdehyde production was observed after 24-h treatment with Spinosad in both Vero and CHO-K1 cells, using fractions of NRU(50) as final concentrations. At concentrations equivalent to its NRU(20), NRU(10) and NRU(5) Spinosad caused significant alterations in the glutathione-redox cycle in the form of significant decrease in total and reduced glutathione, large increase in glutathione peroxidase activity, little induction of glutathione reductase, and significant decline of glutathione S-transferase activities.