Comparative evaluation of two different Opuntia ficus-indica extracts for blood sugar lowering effects in rats

Stems of Opuntia ficus-indica (L.) Mill. (OFI) are traditionally used in Mexico to treat diabetes mellitus. Less research data are available for combinations of stem and fruit preparations. The present study was designed to investigate the effects of an aqueous extract prepared from the cladodes and a proprietary stem/fruit skin-blend (stem/fruit skin ratio 75/25) of OFI on blood glucose and plasma insulin in normal rats. A dose finding study with the traditional cladode OFI extract revealed that maximum effects on blood glucose and insulin were observed after oral administration in a dose range of 6-176 mg/kg. The proprietary OFI blend significantly lowered blood glucose levels in the glucose tolerance test to a similar extent (p < 0.05 vs control) as the traditional aqueous cladode extract when administered in a dose of 6 mg/kg. In contrast to the aqueous extract, the proprietary blend significantly increased basal plasma insulin levels (p < 0.01 vs control) indicating a direct action on pancreatic beta cells. The results suggest that both OFI extracts exert hypoglycemic activities in rats in doses as low as 6 mg/kg but that the effects of the proprietary stem/fruit blend were more pronounced in our model.