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Effect of natural phenols on the catalytic activity of cytochrome P450 2E1

100%

Mikstacka R. , Gnojkowski J. , Baer-Dubowska W.

Acta Biochimica Polonica

2002

tom 49

nr 4

The effect of protocatechuic acid, tannic acid and trans-resveratrol on the activity of p-nitrophenol hydroxylase (PNPH), an enzymatic marker of CYP2E1, was examined in liver microsomes from acetone induced mice. trans-Resveratrol was found to be the most potent inhibitor (IC50 = 18.5 ± 0.4 uM) of PNPH, while protocatechuic acid had no effect on the enzyme activity. Tannic acid with IC50 = 29.6 ± 3.3 uM showed mixed- and trans-resveratrol competitive inhibition kinetics (Ki = 1 uM and 2.1 uM, respectively). Moreover, trans-resveratrol produced a NADPH-dependent loss of PNPH activity, suggesting mechanism-based CYP2E1 inactivation. These results indicate that trans-resveratrol and tannic acid may modulate cytochrome P450 2E1 and influence the metabolic activation of xenobiotics mediated by this P450 isoform.

Effect of fructans with different degrees of polymerization on bacterial enzymes activity, lipid profile and antioxidant status in rats

100%

Zary-Sikorska E. , Juskiewicz J.

Polish Journal of Food and Nutrition Sciences

2008

tom 58

nr 2

The aim of the study was to compare the effect of two types of fructans characterised by a different degree of polymerization (long-chain inulin and short-chain fructooligosaccharides [FOS]), added as single dietary components on the activity of selected bacterial enzymes in the faeces and the caecal digesta, the antioxidant status and the serum lipid profile in laboratory rats. Twenty four male Wistar rats were randomly divided into three groups and for 4 weeks were fed a control casein and two experimental diets supplemented with fructooligosaccharides and inulin at a level of 7.5% of diet (C, FOS and IN groups, respectively). The inulin addition caused a significant decrease in faecal pH value throughout the study (pH measurements were taken after day 7, 14, 21 and 28 of feeding), whereas the FOS-diet significantly decreased pH of fresh faeces only after 3 weeks of the study (p<0.05 vs. the control). Both experimental diets beneficially diminished the activity of faecal β-glucosidase and β-glucuronidase as compared to the control animals. The decreased activity of bacterial β-glucosidase and increased activity of β-galactosidase in the caecal digesta was noted only in the case of dietary FOS. The lowest concentrations of TBARS in the liver, kidneys and serum were observed in the IN group (p<0.05 vs. the control), however the FOS diet also effectively reduced concentration of TBARS in the liver tissue and the serum. The dietary inulin significantly decreased the serum glucose level and increased the percentage of HDL-cholesterol in total cholesterol (vs. C and FOS groups). The results obtained demonstrate that the consumption of diet supplemented with inulin seems to be more health promoting and elicits more beneficial changes in microflora activity, lipid metabolism and antioxidant status in rats than that enriched with short-chain fructooligosaccharides.