Nitric oxide in paraquat‐mediated toxicity: A review

Abstract

Paraquat, a cationic herbicide, produces degenerative lesions in the lung and in the nervous system after systemic administration to man and animals. Many cases of acute poisoning and death have been reported over the past few decades. Although a definitive mechanism of toxicity of paraquat has not been delineated, a cyclic single electron reduction/oxidation is a critical mechanistic event. The redox cycling of paraquat has two potentially important consequences relevant to the development of toxicity: the generation of the superoxide anion, which can lead to the formation of more toxic reactive oxygen species which are highly reactive to cellular macromolecules; and the oxidation of reducing equivalents (e.g., NADPH, reduced glutathione), which results in the disruption of important NADPH-requiring biochemical processes necessary for normal cell function. Nitric oxide is an important signaling molecule that reacts with superoxide derived from the paraquat redox cycle, to form the potent oxidant peroxynitrite, which causes serious cell damage. Although nitric oxide has been involved in the mechanism of paraquat-mediated toxicity, the role of nitric oxide has been controversial as both protective and harmful effects have been described. The present review summarizes recent findings in the field and describes new knowledge on the role of nitric oxide in the paraquat-mediated toxicity.

Protective effects of intranasal curcumin on paraquot induced acute lung injury (ALI) in mice

“…Studies have proved that PQ induced reactive oxygen species induce the expression of nitric oxide synthase (NOS) (Morán et al, 2010). PQ induced lung injury could be inhibited by using NOS inhibitors as nitric oxide (NO) play a crucial role in PQ toxicity (Mustafa et al, 2002).…”

Differential responses of hydrogen peroxide, lipid peroxidation and antioxidant enzymes in Azolla microphylla exposed to paraquat and nitric oxide

“…Among different herbicides, Paraquat (1,1'-dimethyl-4,4'-bipyridinium, PQ) is the most widely used herbicide in the world because of its greater efficiency and low cost (Qian et al 2009a;Moran et al 2010). It blocks photosynthesis by accepting electrons from photosystem I (PSI) and causes overproduction of reactive oxygen species (ROS) which caused alteration of the main biomolecule classes, leads to structural and func-1120 A.…”

“…It blocks photosynthesis by accepting electrons from photosystem I (PSI) and causes overproduction of reactive oxygen species (ROS) which caused alteration of the main biomolecule classes, leads to structural and func-1120 A. Sood et al tional changes in lipids, proteins, chlorophylls, and nucleic acids (Qian et al 2009a;Moran et al 2010;Sood et al 2011). Holst et al (1982 observed that bipyridilium and phenolic herbicides were detrimental to A. mexicana, causing up to 75% reduction in N 2 fixation.…”

“…Literature have shown that application of the NO donor reduces harmful effects of salinity (Chen et al 2010), high light levels (Xu et al 2010), herbicides (Qian et al 2009b;Ferreira et al 2010) and heavy metals on plants (Moran et al 2010;Siddiqui et al 2011). However, the effect of NO can either be protective or toxic, depending on its concentration and on the site of action (Siddiqui et al 2011).…”

Protective effect of adiponectin on paraquat-induced pulmonary fibrosis in mice

“…PQ can be deoxidated to form free radicals using elec trons supplied by NADPH; the deoxidated PQ then reacts with molecular oxygen to form O2 -and bipyri dine cations. O2 -is used to produce hydrogen perox ide through the action of superoxide dismutase (SOD); O2 -can also form hydroxyl radicals and other more toxic ROS, thereby inducing an imbalance in the ox idationantioxidant response and generating lung in jury 1,23 . Our data showed that the proportion of O2 -cells was significantly higher in the PQ group than in the control group, while the proportion of O2 -cells was significantly lower at each time point in the APN group than in the PQ group (P<0.01).…”