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Quercetin and diabetes patients

Kobori of the National Agriculture and Food Research Organization, Ibaraki, Japan, investigated the effect of quercetin on the improvement of the diabetic symptoms [1]. They conducted experiments on streptozotocin-induced diabetic rats to determine the effect of quercetin on liver injury. Quercetin was fed for two weeks, after which hepatic gene expression was measured using a DNA microarray. Quercetin administration lowered the streptozotocin-induced increase in blood glucose levels and improved plasma insulin levels. A diet with 0.5% quercetin suppressed streptozotocin-induced alteration of gene expression.

A study by Chao and co-workers at Taoyuan General Hospital, Taiwan., demonstrated the protective effect of quercetin and its glucuronide and sulfate metabolites against glucose induced of human endothelial cells [2]. The researchers found that the quercetin metabolites inhibited in a dose-dependently manner the glucose-induced apoptosis. The quercetin metabolites inhibited Jun N-terminal kinase and caspase-3 and reduced intracellular H2O2 level. They concluded that quercetin may have a pharmacological application in treating cardiovascular disease in diabetes mellitus patients.

Winged Spindle is used in China as a folk medicine to treat type 2 diabetes. This herb is rich in kaempferol and quercetin. Scientists from the Chinese Pharmaceutical University investigated the possible mechanism of antidiabetic activity of these phytochemicals in cultured adipocytes [3]. They concluded that "kaempferol and quercetin potentially act at multiple targets to ameliorate hyperglycemia, including by acting as partial agonists of glitazone receptor".

[1] Dietary quercetin alleviates diabetic symptoms and reduces streptozotocin-induced disturbance of hepatic gene expression in mice. Mol Nutr Food Res. 2009 Jul;53(7):859-68.
[2] The antioxidant effects of quercetin metabolites on the prevention of high glucose-induced apoptosis of human umbilical vein endothelial cells. Br J Nutr. 2009 Apr;101(8):1165-70.
[3] Kaempferol and quercetin isolated from Euonymus alatus improve glucose uptake of 3T3-L1 cells without adipogenesis activity. Life Sci. 2008 Mar 12;82(11-12):615-22.

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