title: Effects of grape extracts on the in vitro activity of enzymes involved in oxidative stress regulation.
abstract: OBJECTIVE
  A number of in vitro and in vivo studies have investigated the potential preventive activity of grape extracts against different diseases, and have mostly focused on their antioxidant properties. The present study examined the effects of 21 extracts from stem, skin and berry from Greek grape varieties on the activity of enzymes involved in regulation of oxidative stress, namely xanthine oxidase (XO), catalase (CAT) and superoxide dismutase (SOD).
  
  
  METHODS
  The effects of the extracts on the enzymatic activity of XO, CAT and SOD were studied spectrophotometrically.
  
  
  RESULTS
  The tested extracts inhibited CAT and XO activity, while higher extract concentrations are required to induce SOD. However, stem and skin extracts exhibited a different inhibitory pattern against CAT and XO compared to berry extracts. The observed differences are possibly attributed to the extract polyphenolic composition.
  
  
  CONCLUSIONS
  Although the induction of SOD activity suggests an antioxidant capacity, the inhibition of CAT and XO indicates a pro-oxidant action. In general, the extracts showed pro-oxidant activity, possibly dependent on both their polyphenolic composition and concentration.
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, Ploutonos 26 & Aiolou, 41221, Larissa, Greece.
authors.forename: Chrysoula
authors.initials: C
authors.lastname: Spanou
authors.forename: Aristidis S
authors.initials: AS
authors.lastname: Veskoukis
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Stagos
authors.forename: Kalliopi
authors.initials: K
authors.lastname: Liadaki
authors.forename: Maria
authors.initials: M
authors.lastname: Anastasiadi
authors.forename: Serkos A
authors.initials: SA
authors.lastname: Haroutounian
authors.forename: Maria
authors.initials: M
authors.lastname: Tsouka
authors.forename: Eleni
authors.initials: E
authors.lastname: Tzanakouli
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Kouretas
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000494:pharmacology; D002374:Catalase / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D008297:Male; D018384:Oxidative Stress / Q000502:physiology*; D010088:Oxidoreductases / Q000378:metabolism*; D010936:Plant Extracts / Q000494:pharmacology*; D013482:Superoxide Dismutase / Q000378:metabolism; D027843:Vitis / Q000737:chemistry*; D014969:Xanthine Oxidase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D010936:Plant Extracts; D010088:Oxidoreductases; D002374:Catalase; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase