Quercetin (QE), one of natural flavonoid group, was widely distributed as a
secondary metabolite in plant k ingdom and recognized as anti-inflammatory,
antiallergic, antiviral, antibacterial and antitumor activity. It has been believed that
oxidative stress plays a role in the pathogenesis of diabetes mellitus (DM). The aim of
the present study was the evaluation of possible effects of QE on blood glucose and
antioxidant enzymes in experimental streptozotocin (STZ)-induced diabetes in rats.
STZ was injected intraperitoneally at a single dose of 50 mg k g
.-1
for diabetes
induction. QE (15 mg k g
.-1
day, intraperitoneal (i.p.) injection) was injected for 3
days prior to STZ administration; these injections were continued to the end of the
study (for 25days).Glucose tolerance test and random plasma glucose were done for
all animals. In order to determine the changes of cellular antioxidant defense system,
antioxidant enzymes such as glutathione peroxidase (GSHPx), superoxide dismutase
(SOD) and catalase (CAT) activities were measured in pancreatic homogenates.
Quercetin had no effect on plasma glucose level of normal animals but its pre-treatment was able to prevent diabetes induced by single i p injection of streptozocin-treated rats. Antioxidant enzyme activity significantly decreased (P < 0.05) in STZ
induced diabetic group. QE treatment significantly increased the antioxidant enzyme
activities (P<0.05). It could be concluded that quercetin, a flavonoid with antioxidant
properties, exerting its beneficial antidiabetic effects. However, it may be of little
value in normoglycemic animals.