title: Protective effect of flavonoids against red blood cell hemolysis by free radicals.
abstract: BACKGROUND
  Flavonoids are polyphenolic substances with antioxidant properties, and they are found in different vegetables and fruits. Epidemiological studies have shown that the consumption of flavonoids reduces the prevalence of cardiovascular diseases. The use of synthetic antioxidants, however, has been limited because of their toxicity. Therefore, medical researchers have intensified their quest to find natural antioxidants.
  
  
  OBJECTIVE
  To investigate the effect of several pure flavonoids, such as kaempferol, quercetin, morin and rutin, on red blood cell hemolysis and evaluate their -SH capacity as an indicator of membrane protection.
  
  
  METHODS
  The rate of hemolysis and cell membrane -SH capacity were determined by spectrophotometry. Red blood cell peroxidation was induced using 2,2'-azo-bis-(2-amidinopropane) dihydrochloride. The effect of each flavonoid on hemolysis was examined at three concentrations (0.5 mug/mL, 5 mug/mL and 10 mug/mL), however, only the greatest concentration (10 mug/mL) of each flavonoid was used to study the effect on -SH groups.
  
  
  RESULTS
  In all cases, the antioxidant activity was dose-dependent. Rutin showed the highest inhibitory effect on hemolysis among flavonoids (42.5%). The protective effect of kaempferol, rutin and morin against -SH group oxidation measured 7.7%, 23.3% and 26.4%, respectively.
  
  
  CONCLUSIONS
  Results showed that flavonoids and flavonoid-containing plants can be used as natural antioxidants for the treatment and prevention of disease conditions, the pathogenesis of which is mediated by lipid peroxidation.
authors.affiliation: Isfahan Cardiovascular Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: S
authors.initials: S
authors.lastname: Asgary
authors.forename: Gh
authors.initials: G
authors.lastname: Naderi
authors.forename: N
authors.initials: N
authors.lastname: Askari