Study of hypoglycemic effect of Juglans regia leaves and its mechanism

Hypoglycemic effect of Juglans regia leaves was reported in other previous researches. To investigate the mechanism of hypoglycemic action of Julans regia Leaves Methanolic Extract [JRLME], we designed the following study. Methods: Male wistar rats were classified in five groups, each of six, including alloxan-induced diabetic rats treated with JRLME at doses of 250 [D+JRLMEa], 500 mg/kg [D+JRLMEb], Acarbose at dose 20 mg/kg [D+Ac], vehicle alone [DC] and normal rats treated with vehicle alone [NC]. The Postprandial blood glucose level was examined in a short time [after a single dose treatment] and a long time [after three weeks daily treatment] model. After three weeks of treatment, all groups' animals were killed to dissect pancreatic and myocardium for RNA extraction and RT-PCR, to assess insulin and glut-4 genes expression, respectively. In addition, other normal rats were killed to extract intestinal brush border membrane for beta-glucosidase solution preparation. The effect of JRLMEa on beta-glucosidase activity was evaluated by an in vitro method, compared to Acarbose as a reference drug. The plant extract had a significant hypoglycemic action in both short and long term models. Decrease in PBG level was the most at 8 hour after treatment and more in D+Ac [53%], D+JRLMEa [40%] and D+JRLMEb [29%] versus DC, respectively. There was also permanent PBG reduction in treated groups in comparison with the DC one during long term period. We did not find change in the insulin and glut-4 genes expression. On the other hand, the in vitro assay of beta-glucosidase activity displayed inhibitory action of JRLME, like Acarbose, but less effectively

Antidiabetic properties of the ethanolic extract of Rhus coriaria fruits in rats

Fruits of Rhus coriaria L. [Anacardiaceae] are traditionally used as a table spice in Iran and are highly recommended for diabetic patients. The purpose of this study was to determine the antidiabetic properties of the ethanolic extract of Rhus coriaria fruits and also its mechanisms of action. The effects of ethanolic extract of Rhus coriaria fruits were measured on blood glucose, lipids and antioxidant enzymes by commercial kits. mRNA levels of insulin [INS] and glucose transporter type-4 [GLUT-4] genes were investigated by RT-PCR [Reverse transcription-polymerase chain reaction] technique. Moreover, its effects on intestinal alpha-glucosidases was measured using an in vitro method. Following a single dose administration of the extract it was found that extract could significantly reduce postprandial blood glucose by 24% [at 5 hrs]. In the long term experiment, on the day of 21, postprandial blood glucose [PEG] was found to be significantly lower [by 26%] compared to diabetic control group. The plant extract raised markedly serum high-density lipoprotein [HDL] by 34% and also reduced low-density lipoprotein [HDL] by 32%. Also it had noticeable antioxidant effects by elevating superoxide dismutase [SOD] and catalase [CAT] activities by 46% and 77%, respectively. However it did not show a strong effect on glutathione peroxidase [GPX] activity. The extract inhibited maltase and sucrase activities by 44% and 27%, respectively. However it made no changes in the transcript levels of INS and GLUT-4 genes. It can be concluded that constituents of Rhus coriaria fruits have effective components which can be utilized as useful herb for alleviation of diabetes complications