Quercetin was assessed for its antihyperglycemic effect in fructose-streptozotocin
(STZ) induced diabetic rats. The oral administration of quercetin at the dosage of
25 and 50 mg/kg for 28 days remarkably reduced the level of blood glucose, glycosylated
hemoglobin (Hb), and hepatic glycogen but enhanced plasma Hb concentration.
The altered activities of glucose-6-phosphatase and hexokinase in diabetic rats
were significantly improved upon quercetin treatment. Furthermore, the antioxidant
activity of pancreatic superoxide dismutase, catalase (CAT), and reduced glutathione
was effectively increased while the value for thiobarbituric acid reactive species was
decreased. A significant reduction of glycemia was observed in the glucose tolerance
test, 120 min after the glucose pulse. Also, the damage caused by fructose-STZ in the
liver and pancreas of diabetic animals were restored to near normal. Molecular docking
of quercetin showed a high affinity for hexokinase and CAT with a binding energy
of ?7.82 and ?9.83 kcal/mol, respectively, more elevated than the standard drugs.
Functional foods and nutraceuticals have increasingly interested the consumers in
terms of health benefits and have started focussing on the prevention or cure of
disease by the foods and their health-enhancing phytochemicals. Quercetin is one
of the most potent naturally occurring antioxidants within the flavonoid subclasses,
mostly distributed as a secondary metabolite in fruits, vegetables, and black tea.
Based on the results exhibited in the present study, we proposed that the consumption
of foods rich in quercetin could be a cheap and affordable nutraceutical that can
be developed for the treatment of T2DM and its complications. Further studies on
the safety aspects of quercetin in long-term usage are strongly recommended before
implementing for the treatment of human diseases.