Chemical constituents of Argyreia speciosa Fam. Convolvulaceae and its role against hyperglycemia

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-ß- 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.