Hypoglycaemic action of the flavonoid fraction of Cuminum nigrum seeds

The seeds of Cuminum nigrum were screened phytochemically and were found to contain 8% flavonoids and 0.01% alkaloids, When studied for their effect o n blood glucose levels, oral administration of the flavonoid contents of th e plant caused a hypoglycaemic effect at a dose range of 0.5 to 1.5 g/kg, b oth in normal and alloxan-diabetic rabbits. The hypoglycaemic effect starte d 2 h after drug administration, reaching a maximum within 4-8 h and the bl ood glucose levels returned close to normal within 24 h of drug administrat ion. The glibenclamide (5 mg/kg), produced a hypoglycaemic effect in the no rmal rabbits, whereas it had no effect on the blood glucose levels of allox an-diabetic rabbits. The alkaloids isolated from C, nigrum seeds, however, failed to exert any significant hypoglycaemic effect in either the normal o r diabetic rabbits. A 7 day acute toxicity study in rabbits did not produce any apparent adverse effect at doses as high as 5 g/kg orally. These data indicate that the total flavonoid contents of C, nigrum seeds exhibited con siderable hypoglycaemic activity in rabbits and may therefore be responsibl e for the previously reported antidiabetic activity of the seeds. Furthermo re, it is conceivable that the C. nigrum flavonoids possess insulin trigger ing and/or insulin-like properties. Copyright (C) 2000 John Wiley & Sons, L td.