Background: Catalase is a basic antioxidant enzyme that exits in human organs, mainly in the liver. The liver as a main tissue in the body that plays a substantial role in the catabolism and detoxification of drugs is a target of toxic and carcinogenic effects of many drugs. In the present study, the side effects of an anti-cancer compound of oxali-palladium on the function and structure of liver catalase were investigated.

Materials and Methods: In this experimental study, changes in the enzyme activity were studied by conversion in substrate (hydrogen peroxide) absorption at wavelength of 240 nm, using UV-visible spectroscopy in the absence and presence of different concentrations of oxali-palladium at room temperature. Furthermore, the effect of oxali-palladium on the tertiary structure of catalase was investigated using fluorescence spectroscopy via studying the changes in the intrinsic enzyme emission in the absence and presence of different concentrations of oxali-palladiumat at both room and physiologic temperatures.

Results: Kinetics data showed that the Km value of bovine liver catalase was 26.8 mM. Moreover, in the presence of different concentrations of oxali-palladium‚ the enzyme activity showed a gradual decrease in a dose-dependent manner (p<0.001). Fluorescence data presented changes in the tertiary structure of the enzyme by quenching fluorescence emission‚ that indicated alteration in protein chromophore environment.

Conclusion: It could be concluded that inhibition of catalase enzyme by anticancer drug of oxali-palladium increases the content of reactive oxygen species. Increase in reactive oxygen species values is one of the chief mechanisms of different anticancer drugs.

Abstract

Background: Oxidative stress plays an important role in the pathogenesis of hypertension- induced cardiac hypertrophy. Plants are a rich source of antioxidant compounds. Thymol is a natural monoterpen phenol which is plentiful in some plants and shows many biological effects. The aim of the present study was to assess the effects of thymol on activity of antioxidant enzyme catalase, malondialdehyde (MDA) level and the activity of the inhibition of free radical DPPH (2,2-Diphenyl-1-picryl-hydrazyl), following left ventricular hypertrophy in rats.

Materials and Methods: In this experimental study, rats were divided into hypertrophied group without any treatment (H group) and rats pretreated with 25 and 50 mg/kg/day of thymol (Thy25+H and Thy50+H groups, respectively). Intact animals were served as control (Ctl). Animal model of left ventricular hypertrophy was induced by abdominal aortic banding. Serum catalase (CAT) activity, malondialdehyde (MDA) level and the activity of inhibition of free radicals DPPH were determined by the biochemical methods.

Results: In Thy25+H and Thy50+H groups, the CAT activity was increased significantly in serum (p<0.01, vs. Ctl). Also, serum level of MDA was decreased significantly compared to the group H in Thy25+H and Thy50+H groups (p<0.05 and p<0.001, respectively). The effect of inhibiting DPPH free radicals was increased significantly in Thy25+H and Thy50+H groups compared to the group H (p<0.001 and p<0.05, respectively).

Conclusion: The findings of this study suggest that thymol as an antioxidant causes cardioprotective effects and as well as prevents left ventricular hypertrophy via augmentation of serum antioxidant capacity.