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The present study was conducted to investigate the protective effects of N-Acetyl-L-cysteine (NAC) and S-methyl- L-cysteine (SMC) against hepatic oxidative stress and brain damage induced by acetamiprid (ACP) in rats, which were evaluated by histopathological changes, measuring serum biomarkers and antioxidant defense systems. In this study, 42 rats were randomly divided into 6 groups and administered by intraperitoneally for one week: the control group, the sham group (normal saline), ACP alone (5 mg/kg) (group1), NAC alone (160 mg/kg) (group2), ACP + SMC (100 mg/kg) (group3), ACP + NAC (group 4) and ACP + NAC + SMC (group 5). Our results showed that acetamiprid induces liver injures including infiltration of inflammatory cells, congestion and altered histo-architecture and brain damages including gliosis, hyperemia and necrosis. The biochemical analyses showed that acetamiprid significantly altered the structural and biochemical profiles of liver which may be due to the loss of integrity of cell membranes. Furthermore, antioxidant parameters results of ACP group revealed that glutathione (GSH) and total antioxidant capacity (TAC) levels decreased significantly, while lipid peroxidation (LPO) content and glutathione-S-transferase (GST) and catalase (CAT) activities increased in both tissues (P < 0.05), suggesting tissue oxidative damage, which was also confirmed histopathological. Conversely, administration of NAC and SMC ameliorated LPO, GSH content and antioxidant enzymes system considerably (P < 0.05) in both tissues. Moreover, NAC and SMC administration also improved liver and brain malfunction. These results indicate that both NAC and in to a lesser amount SMC have a potent antioxidant protection in both tissues of rat against ACP-induced oxidative stress.

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Background: Lactate dehydrogenase (LDH) is a tetrameric enzyme that catalyzes the interconversion of pyruvate to L-lactate. The importance of this enzyme is because LDH isoenzymes are involved in cancer, heart, and liver diseases. Inhibition of this enzyme can help prevent and treat different diseases. Morin is a flavonoid found in the Moraceae family and scopoletin is a coumarin found in Scopolia genus. Objectives: The aim of this study was to determine the effect of morin and scopoletin as two natural products on the activity and structure of lactate dehydrogenase enzyme. Methods: Morin and scopoletin were examined for inhibition of the activity of LDH in 100 mM sodium phosphate buffer pH 7.5, at room temperature using UV-V spectrophotometry. Fluorescence spectroscopy was used to characterize protein structural changes in the presence of morin and scopoletin. Results: Km and Vmax of LDH for pyruvate were 11.69 mM and 1.258 mM/min, respectively. The kinetic results showed that morin and scopoletin are LDH inhibitors. The Ki values of morin and scopoletin were determined as 1.78 µM and 0.8 µM, respectively, using a secondary plot. Fluorescence intensity quenching and red shift of the maximum wavelength of emission in a concentrationdependent manner showed that morin and scopoletin bind to LDH and affect its structure. Conclusions: The results suggest that morin and scopoletin bind to LDH, influence its conformation and inhibit its activity. Scopoletin showed more effective inhibition of LDH activity and it can be a promising candidate in the field of tumor metabolism inhibitors.