The Influence of Antioxidant Resveratrol on Paraquat-induced Oxidative Stress in Cultured Lung Cells

PURPOSE: Paraquat (1,1'-dimethy-4,4'-bipyridinium dichloride, PQ) is an effective and widely used herbicide, which was introduced commercially in 1962. It is reduced by an electron donor, such as NADPH, and then transfers the electron to molecular oxygen. As a result, the reactive oxygen species (ROS) produced are related to its cellular toxicity. Resveratrol (trans-3,4',5-trihydroxystilbene), a naturally occurring hydroxystilbene, is considered an essential antioxidative constituent of red wine, possessing chemopreventive properties. However, the influence of resveratrol on PQ-induced oxidative cell damage has not fully been investigated. METHODS: This experiment was conducted in vitro using cultured lung cells from SD rats. The MTT and LDH methods were used for assessment of cytotoxicity. The 2',7'-dichlorofluorescein diacetate (DCF-DA) assay was used for measurement of intracellular ROS levels. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was used for measurement of pro-oxidant capacity of resveratrol. The Thiobarbituric acid reactive substances (TBARS) assay, which reflects lipid peroxidation, was used for estimation of oxidative stress. RESULTS: According to results of the MTT and LDH assays, incubation of cultured lung cells with resveratrol did not protect lung cells from PQ-induced cytotoxicity, and no decrease in ROS production was observed, according to results of the DCF-DA assay. On the other hand, incubation of lung cells with non-lethal resveratrol resulted in aggravation of PQ-induced oxidative stress. CONCLUSION: Results of this study showed that incubation of cells with resveratol did not result in reduction of PQ toxicity, but lead to elevation of PQ-induced oxidative stress in cultured lung cells.

Continuous hypoxia attenuates paraquat-induced cytotoxicity in the human A549 lung carcinoma cell line

Paraquat (1,1'-dimethyl-4,4'-bipyridinium dichloride; PQ), an effective and widely used herbicide, was commercially introduced in 1962. It is reduced by the electron donor NADPH, and then reduced PQ transfers the electrons to molecular oxygen, resulting in the production of reactive oxygen species (ROS), which are related to cellular toxicity. However, the influence of continuous hypoxia on PQ-induced ROS production has not fully been investigated. We evaluated in vitro the protective effect of continuous hypoxia on PQ-induced cytotoxicity in the human carcinogenic alveolar basal epithelial cell line (A549 cells) by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and live and dead assay, and by measuring lactate dehydrogenase (LDH) release. To elucidate the mechanism underlying this effect, we monitored the immunofluorescence of intracellular ROS and measured malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GPx) activities. Continuous hypoxia protected the A549 cells from PQ-induced cytotoxicity. Continuous hypoxia for a period of 24 h significantly reduced intracellular ROS, decreased MDA concentration in the supernatant, and normalized SOD and GPx activities. Continuous hypoxia attenuated PQ-induced cell toxicity in A549 cells. This protective effect might be attributable to the suppression of PQ-induced ROS generation.