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

BACKGROUND AND THE PURPOSE OF THE STUDY: 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. METHODS: 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 a-glucosidases was measured using an in vitro method. RESULTS AND CONCLUSION: 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 (PBG) 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.