ABSTRACT
The present work on the aerial parts of Argyreia speciosa Sweet (Convolvulaceae) has led to the isolation of a new lipid ester (1) and four coumarin compounds (2-5). The new compound has been characterized as stigmasteryl formate. The coumarins were identified as 7- hydroxy-6-methoxycoumarin; 6, 7-dihydroxycoumarin; furanocoumarin and scopoletin-7-O-β- glucopyranoside. Isolation of these constituents was performed using chromatographic techniques. Their structures were established through chemical and spectral analysis. Our aim was to demonstrate the antidiabetic activity of the ethanolic extract obtained from Argyreia speciosa, and investigated in normal and alloxan-induced diabetic rats. Glibenclamide was used as a reference drug. Hypoglycemic activity was assessed by a significant reduction in blood glucose and elevation of Liver glycogen content in diabetic rats, a significant decrease in LDH, while glucose-6-phosphatase enzyme showed significant increase. The lipid profile of diabetic group revealed a significant increase in total cholesterol, triglycerides and LDL-C, while HDLC showed significant decrease. Antioxidant status in liver was determined by measuring the activity of lipid peroxides which revealed a significant rise in it’s level, while glutathione level was depleted. Argyreia speciosa showed recovery in hyperglycemia and successfully prevented the alterations of other biochemical parameters. Histopathological study of liver, kidney, pancreas and spleen was also carried out to confirm the protection offered by the ethanolic extract. Data showed that Argyreia speciosa possessed strong antioxidant activity, remarkable antidiabetogenic effect comparable to glibenclamide, a well known liver protecting herbal formula.
ABSTRACT
48 adult male albino rats of an average weight of 150 to 200 g were used to study the effect of different stressors; restraint, water immersion and cold exposure on both serum and gastric tissue Ca2+, Li+ and Zn2+ levels and their correlation with the changes in composition of gastric juice and with the development of gastric stress ulcers. Zinc sulphate pretreatment was also studied to test for a possible protective effect. The gastric juice was collected after pyloric ligation and analyzed for the volume, total acidity and proteolytic activity. Both serum and gastric tissue Ca2+, Li+ and Zn2+ were measured and the gastric mucosal lesions were scored. The ulcer and preventive indices were then calculated. The results were compared with those of a control non stressed group. It was found that all forms of stress reduced significantly the rate of gastric secretion probably secondary to gastric mucosal ischaemia. Neither the serum nor the gastric tissue levels of the gastric stimulant Ca2+, or the gastric inhibitory Li+ and Zn2+ are significantly changed and hence their role in the secretory changes and stress ulcer development was not evident. However, increasing the serum and gastric tissue Zn2+ concentration following zinc sulphate pretreatment could inhibit gastric secretion and exert a protective effect against the different forms of stress ulcer