Antidiabetic effect of Nelumbo nucifera (Gaertn) extract: Part II

AbstractEarlier studies showed that the extract of Nelumbo nucifera Gaertn., an aquatic Indian plant, produced hypoglycaemia and an improvement of glucose tolerance in normal rabbits. Further investigations were undertaken. Chronic administration of plant extracts (test drugs) to normal rats did not produce a sustained fall of fasting blood sugar levels although daily doses caused hypoglycaemia as an acute effect; concurrent glucose tolerance studies showed beneficial effects. In vitro studies with rat hemidiaphragms revealed that test drug treatment of donor animals significantly enhanced the effect of insulin. The improvement of glucose tolerance therefore may also be due to increased peripheral glucose utilization caused by increased sensitivity of skeletal muscles to endogenous insulin. Comparative studies were also carried out in moderately diabetic rabbits using test drugs (equivalent to 1000 mg/kg of crude material) and standard drugs phenformin and tolbutamide (100 mg/kg each). The test drugs showed acute and chronic effects in suppressing hyperglycaemia, but were less potent than standard drugs. However, test drugs significantly improved glucose tolerance in these animals. With severely diabetic rabbits, these drugs proved to be ineffective even at four‐fold higher doses. Toxicity studies in normal rats did not show any deleterious effect on kidney, heart or liver during an 8‐week study period.