RESUMO
The aim of this study was to assess the antioxidant effect of phytosterol from palm oil by studying its ability to improve antioxidant status of rats induced with oxidative stress by carbon tetrachloride (CCl4). The rats were divided into four groups of normal control (NC), carbon tetrachloride (CCl4), phytosterol (P) and phytosterol plus carbon tetrachloride (P+CCl4). The P and P+CCl4 groups received weekly phytosterol pre-treatment via subcutaneous injections at 140 mg/kg rat weight for 5 weeks while the NC and CCl4 groups only received olive oil (vehicle). Carbon tetrachloride at the dose determined by a preliminary study was given as single oral dose to induce lipid peroxidation in the CCl4 and P+CCl4 groups. After 24 hours, the rats were sacrificed and the heart, liver, kidney and lung were isolated for the determination of reduced glutathione (GSH) and oxidized glutathione (GSSG) levels. Carbon tetrachloride caused significant reduction in the GSH:GSSH ratio in all major organs. Phytosterol pre-treatment as in the P+CCl4 group significantly increased the GSH:GSSG ratio in major organs. The present findings indicate that phytosterols keep tissue glutathione concentration in normal levels which may indicate improving antioxidant status in major organs of the rats treated with carbon tetrachloride.
RESUMO
OBJECTIVES: This study was conducted to determine whether the blood pressure-lowering effect of Nigella sativa might be mediated by its effects on nitric oxide, angiotensin-converting enzyme, heme oxygenase and oxidative stress markers. METHODS: Twenty-four adult male Sprague-Dawley rats were divided equally into 4 groups. One group served as the control (group 1), whereas the other three groups (groups 2-4) were administered L-NAME (25 mg/kg, intraperitoneally). Groups 3 and 4 were given oral nicardipine daily at a dose of 3 mg/kg and Nigella sativa oil at a dose of 2.5 mg/kg for 8 weeks, respectively, concomitantly with L-NAME administration. RESULTS: Nigella sativa oil prevented the increase in systolic blood pressure in the L-NAME-treated rats. The blood pressure reduction was associated with a reduction in cardiac lipid peroxidation product, NADPH oxidase, angiotensin-converting enzyme activity and plasma nitric oxide, as well as with an increase in heme oxygenase-1 activity in the heart. The effects of Nigella sativa on blood pressure, lipid peroxidation product, nicotinamide adenine dinucleotide phosphate oxidase and angiotensin-converting enzyme were similar to those of nicardipine. In contrast, L-NAME had opposite effects on lipid peroxidation, angiotensin-converting enzyme and NO. CONCLUSION: The antihypertensive effect of Nigella sativa oil appears to be mediated by a reduction in cardiac oxidative stress and angiotensin-converting enzyme activity, an increase in cardiac heme oxygenase-1 activity and a prevention of plasma nitric oxide loss. Thus, Nigella sativa oil might be beneficial for controlling hypertension.