Apostolos Angelis

Athens State University, Athens, Alabama, United States

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Publications (7)15.64 Total impact

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    ABSTRACT: 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.
    Journal of physiology and biochemistry 03/2012; 68(1):37-45. · 1.65 Impact Factor
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    ABSTRACT: 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.
    PLoS ONE 01/2012; 7(3):e32214. · 3.53 Impact Factor
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    ABSTRACT: 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.
    Journal of Natural Products 11/2011; 74(11):2362-70. · 3.29 Impact Factor
  • Planta Medica 07/2009; 75(09). · 2.35 Impact Factor
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    ABSTRACT: 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.
    Journal of Agricultural and Food Chemistry 08/2008; 56(16):6967-76. · 3.11 Impact Factor
  • Planta Medica - PLANTA MED. 01/2008; 74(09).
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    ABSTRACT: It is believed that legumes are a very good source of micronutrients and phytochemicals that present chemopreventive activity against diseases such as diabetes, coronary heart disease and colon cancer. Methanolic and aqueous extracts from 11 unique varieties of Leguminosae family plants cultured in Greece were tested using three different in vitro assays in order to investigate the mechanisms by which phytochemicals present in these legumes exert their chemoprevention. The extracts were tested by the 1, -diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, the hydroxyl radical- and the peroxyl radical-induced DNA strand scission assays. Hydroxyl (OH*) and peroxyl (ROO*) radicals were generated from ultraviolet (UV) photolysis of hydrogen peroxide (H2O2) and thermal decomposition of 2,2'-azobis-(2-amidinopropane hydrochloride) (AAPH) respectively. In the DPPH assay, all the tested extracts displayed potent radical scavenging efficiency. Furthermore, most of the Leguminosae family plant extracts exerted significant protective activity against DNA damage induced by both reactive oxygen species, although they were more effective in inhibiting ROO*-induced rather than OH*-induced DNA strand scission. The results suggest that the free radical scavenging activity of Leguminosae plants may be one of the mechanisms accounting for their chemoprevention.
    Anticancer research 01/2007; 27(5A):3403-10. · 1.71 Impact Factor