Effect of Ascorbic Acid on Antioxidant Defense Systems and Lipid Peroxidation in Guinea Pig

Abstract

In view of the antioxidant properties of ascorbic acid (AA), effects of inadequate and excessive doses of AA on hepatic and pulmonary antioxidant enzymes and NADPH-dependent lipid peroxidation were investigated in the present study. Male guinea pigs, dosed daily with 0.2 mg AA/100 g b wt (inadequate) or 50 mg AA/100 g b wt (excessive) for 8 weeks, demonstrated no difference in body growth, liver and lung weights, and post-10,000 X g supernatant protein contents as compared with the control group, which was daily fed with 2 mg AA/ 100 g b wt. Inadequacy of AA decreased the hepatic and pulmonary contents of catalase, glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD), but it significantly increased glutathione reductase (GR) activity (p <0.005) in lung. However, levels of hepatic and pulmonary NADPH-dependent lipid peroxidation remained unaltered when the supply of AA was inadequate. Excessive doses of AA did not influence any pulmonary antioxidant enzyme, level of NADPHdependent lipid peroxidation and content of reduced glutathione (GSH), but increased the hepatic GSH-Px and GR activities. Hepatic SOD activity showed a significant decrease (p <0.01), whereas NADPHdependent lipid peroxidation and GSH contents remained unchanged. It appears that the changes in antioxidant enzymes may be a nonspecific response to AA or these changes may not be sufficient to bring about any shift in the levels of NADPH-dependent lipid peroxidation in the presence of unaltered GSH contents or other biomolecules which may act as antioxidants or free radical scavengers in the cell system.

Vitamin C Mediated Minimisation of Malathion and Rogor Induced Mitoinhibition and Clastogeny.

“…Vitamin C is well known to hydrolyse lipids and cholesterol (Rees and Slaten 1987, Fuzimoto et al 1988, Wafer and Sies 1988, Koul et al 1989. Hence the antimitoinhibitory and anticlastogenic effect of the vitamin C, as observed in the present case, may be due to this vitamin C-mediated hydrolysis of the lipid/cholesterol, thus minimising the chances of the formation of mutagenic conjugate of pesticide with them.…”

The antioxidant defense system of isolated guinea pig Leydig cells

“…Whole testicular homogenates were found to contain significantly (P < 0.001) more glutathione peroxidase but significantly (P < 0.001) less glutathione reductase, total glutathione (oxidized + reduced forms) and glucose-6-phosphate dehydrogenase (G-6-PDH) when compared to enriched Leydig cell fractions ( Table 2). The levels of glutathione peroxidase and reductase (units/mg protein) found in Leydig cells were nearly 14 and 11 times less, respectively, than the hepatic values reported in the guinea pig liver [29].…”

“…Greater than 80% of the SOD present in the testes was of the Cu/Zn variety. Compared to the hepatic level (8.66 + 0.91) reported in the guinea pig liver [29], the testicular level of total SOD (units/mg protein) was 1.7 times higher (14.87 + 0.43) and the enriched Leydig cell level was only slightly higher (10.18 _+ 0.80). No significant differences were discerned in the catalase content of whole testicular homogenates and of enriched Leydig cell fractions (Table 1).…”

“…Leydig cells contained nearly 400 times less catalase (units/rag protein) than the hepatic value (2,168 _+ 135) reported in the liver [29]. Whole testicular homogenates were found to contain significantly (P < 0.001) more glutathione peroxidase but significantly (P < 0.001) less glutathione reductase, total glutathione (oxidized + reduced forms) and glucose-6-phosphate dehydrogenase (G-6-PDH) when compared to enriched Leydig cell fractions ( Table 2).…”

Impact of Vitamin B12 against Pesticide Induced Mitoinhibition and Clastogeny.

“…Riboflavin on this point may act similar to vitamin C (Rees and Slaten 1887, Fuzimoto et al 1988, Wafer and Sies 1988. Frequency distribution (n) of various types of chromosome/chromatid abnormalities scored after pesticide and Vitamin treatment Koul et al 1989). Bhattacharya et al (1987) tested 19 vitamins including some members of the B-complex group and their derivatives for their ability to suppress mutagenic activity of certain environmental mutagens.…”