The hypoglycaemic effect of annatto (bixa orellana) - abstract

ABSTRACT

In West Indian folklore, a number of plant extracts are utilised for medicinal purposes. One common malady so treated is diabetes mellitus. Some twenty (20) folk medicines (bush tea) were investigated as to their efficacy in lowering blood sugar levels in the anaesthetised dog model. The annatto (bixa orellana) when prepared as an oil suspension of the red seed coat was found to be quite a potent hypoglycaemic agent. It was further studied in order to purify the crude extract and possibly identify the pharmacologically active agent(s). The annatto seeds were percolated with chloroform until the bright red colour of the seed coat was removed. This extract was concentrated in vacua and the residue extracted selectively with 60 percent ethanol/water and petroleum ether. A final wine-red to orange viscous extract was used in the biological experiments. This partially purified petroleum ether extract was dissolved in corn oil (80 mg/kg body weight animal) and given to anaesthetized dogs via a stomach tube. After a residence time of one (1) hour, oral glucose tolerance tests were performed. The results showed hypoglycaemia in both the normal and streptozotocin diabetic dogs when compared to controls. Its effect is to delay the peaking of glucose after a meal and to increase the release of insulin in relation to blood glucose levels. The possibility of an effective hypoglycaemic principle in this extract increases pharmacological curiosity into this form of 'lay' treatment of diabetes mellitus. Detailed studies are continuing to identify and isolate the active component(s) (AU)