Time-Related Evidence of Intestinal Oxidative Stress in Obstructive Jaundice-Induced Rats.

INTRODUCTION: Obstructive jaundice is known to affect intestinal permeability and facilitate bacterial translocation through related mechanisms. This study was conducted to evaluate the alterations concerning blood biochemistry and levels of several markers of oxidative stress (OS) in blood and intestinal mucosa caused by obstructive jaundice and how these fluctuate over time, in order to further explore the possibility of intervening in the OS path in future experiments. METHODS: A total of 54 albino Wistar rats were randomly divided into three groups (control, sham operated, and bile duct ligation) and sacrificed at specific time intervals (12 h and 2, 7, and 14 days). The intestinal barrier function was evaluated by measuring endotoxin levels in portal, aortic, and peripheral blood. Also, basic biochemical parameters were simultaneously measured in peripheral blood. Tissue samples collected from the terminal ileum were homogenized for determining the OS markers, lipid peroxidation, and protein-free radical-induced oxidation. RESULTS: We designed this experiment to examine the alterations in enteric mucosa primarily in relation to OS in a period of 14 days. During this time period, we investigated in specific time intervals not only OS fluctuations but also other liver function parameters, as well as CRP and endotoxin levels. The alterations were monitored in relation to time after bile duct ligation. CONCLUSION: Bile duct ligation in rats causes OS versus post-ligation time progression of the common bile duct. OS was increased by ∼50% compared to control/sham and peaked at 7 days and at least up to 14 days post-ligation. This phenomenon was accompanied with a deranging of liver function after ligation, as anticipated, but not in all measured parameters; biochemical and endotoxin levels followed the same pattern.

Flavonoid glycosides isolated from unique legume plant extracts as novel inhibitors of xanthine oxidase.

Legumes and the polyphenolic compounds present in them have gained a lot of interest due to their beneficial health implications. Dietary polyphenolic compounds, especially flavonoids, exert antioxidant properties and are potent inhibitors of xanthine oxidase (XO) activity. XO is the main contributor of free radicals during exercise but it is also involved in pathogenesis of several diseases such as vascular disorders, cancer and gout. In order to discover new natural, dietary XO inhibitors, some polyphenolic fractions and pure compounds isolated from two legume plant extracts were tested for their effects on XO activity. The fractions isolated from both Vicia faba and Lotus edulis plant extracts were potent inhibitors of XO with IC(50) values range from 40-135 µg/mL and 55-260 µg/mL, respectively. All the pure polyphenolic compounds inhibited XO and their K(i) values ranged from 13-767 µM. Ten of the compounds followed the non competitive inhibitory model whereas one of them was a competitive inhibitor. These findings indicate that flavonoid isolates from legume plant extracts are novel, natural XO inhibitors. Their mode of action is under investigation in order to examine their potential in drug design for diseases related to overwhelming XO action.

Effects of Greek legume plant extracts on xanthine oxidase, catalase and superoxide dismutase activities

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Legumes are considered to have beneficial health implications, which have been attributed to their phytochemical content. Polyphenols are considered the most important phytochemical compounds extensively studied for their antioxidant properties. The aim of the present study was to examine the effects of potent antioxidant legume plant extracts on xanthine oxidase (XO), catalase (CAT) and superoxide dismutase (SOD) activities. XO exerts a dual role, as it is the major contributor of free radicals during exercise while it generates uric acid, the most potent antioxidant molecule in plasma. CAT and SOD are two of the main enzymes of the antioxidant defence of tissues. We demonstrate that the majority of the extracts inhibited XO activity, but they had no effect on CAT inhibition and SOD induction when used at low concentrations. These results imply that the tested extracts may be considered as possible source of novel XO inhibitors. However, we have shown that allopurinol administration, a known XO inhibitor, before exercise reduces performance and induces oxidative stress in rats. Considering the fact that the extracts examined had an inhibitory effect on XO activity, possibly posing a restriction in their characterization as antioxidants, phytochemical antioxidant administration before exercise should probably be reconsidered (AU)

Effects of Greek legume plant extracts on xanthine oxidase, catalase and superoxide dismutase activities.

Legumes are considered to have beneficial health implications, which have been attributed to their phytochemical content. Polyphenols are considered the most important phytochemical compounds extensively studied for their antioxidant properties. The aim of the present study was to examine the effects of potent antioxidant legume plant extracts on xanthine oxidase (XO), catalase (CAT) and superoxide dismutase (SOD) activities. XO exerts a dual role, as it is the major contributor of free radicals during exercise while it generates uric acid, the most potent antioxidant molecule in plasma. CAT and SOD are two of the main enzymes of the antioxidant defence of tissues. We demonstrate that the majority of the extracts inhibited XO activity, but they had no effect on CAT inhibition and SOD induction when used at low concentrations. These results imply that the tested extracts may be considered as possible source of novel XO inhibitors. However, we have shown that allopurinol administration, a known XO inhibitor, before exercise reduces performance and induces oxidative stress in rats. Considering the fact that the extracts examined had an inhibitory effect on XO activity, possibly posing a restriction in their characterization as antioxidants, phytochemical antioxidant administration before exercise should probably be reconsidered.

Catalytic inhibition of eukaryotic topoisomerases I and II by flavonol glycosides extracted from Vicia faba and Lotus edulis.

Topoisomerases are essential enzymes involved in all processes of DNA metabolism, and their inhibitors have been identified as potential anticancer agents. The present study examined the effect of nine polyphenolic compounds derived from parts of two unique varieties of the Leguminosae, Vicia faba and Lotus edulis, on the activity of eukaryotic topoisomerases. We identified polyphenolic compounds that act as catalytic inhibitors of wheat germ topoisomerase I (IC50: 120-350 µM), human topoisomerase I (IC50: 110-260 µM), and human topoisomerase II (IC50: 240-600 µM) activities. Some compounds inhibited all enzymatic activities to a similar extent, while others exhibited specificity toward individual enzymes. The strongest catalytic inhibitor of all the examined enzymes was a kaempherol glycoside with an acetyl group linked to a sugar moiety. In addition, this compound inhibited the growth of human cancer cell lines MCF7, HeLa, and HepG2. The inhibition of topoisomerase I and II activities observed by the specific compounds possibly implies a role as potential agents in the prevention and therapy of cancer.

Antioxidant and chemopreventive properties of polyphenolic compounds derived from Greek legume plant extracts.

Recently, phytochemical compounds present in legumes have gained a lot of interest because they are considered to be possible chemopreventive agents. In the present study, 14 polyphenolic compounds were extracted and identified from two unique varieties of Leguminosae family plants cultivated in Greece and screened for their antioxidant and chemopreventive properties. Ten polyphenolic fractions, which are mainly mixtures of two compounds and five pure flavonoids, were isolated from the methanolic extracts of aerial plant parts of Vicia faba and Lotus edulis (Leguminosae), respectively. All of these fractions exhibited significant DPPH(*) radical scavenging capacity. Furthermore, they exerted significant protective activity against free radical-induced DNA damage. This activity was more potent against ROO(*) radical-induced DNA damage than against that induced by OH(*) radicals. Finally, they exhibited significant ability to inhibit the activity of the topoisomerase I enzyme. These results imply that the polyphenolic compounds identified in the fractions were responsible of the observed properties of the fractions and the initial extracts and indicate different mechanisms by which these phenolic compounds may act as chemopreventive agents.