Blood glucose lowering effect of ethanol leaf extract of <i>Hymenodictyon Floribundum</i> (Rubiaceae)

Abstract

In developing countries, and some developed nations, diseases are managed using complementary medicine with the aid of preparations from a single or mixture of herbs. Diabetes mellitus, described by persistently high blood glucose levels, owing to abnormalities in insulin secretion, is among such disorders. Hymenodictyon floribundum has been reported to be used in ethnomedicine to manage diabetes. This study aimed to investigate the blood glucose-lowering activity of the ethanol extract of Hymenodictyon floribundum leaves in adult Wistar rats. Elemental analysis, preliminary phytochemical screening, and acute toxicity test were carried out. Oral glucose tolerance test (OGTT) was performed using five groups of adult Wistar rats administered graded doses (375, 750, and 1500 mg/kg) of the extract, distilled water (1 mL/kg) as negative control, and metformin (500 mg/kg) as positive control. Measurement of glucose levels in blood was performed at 0, 30, 60, and 120 minutes of extract administration, respectively. The result of the elemental analysis indicated the presence of Ca, Mg, K, Na, Fe, Mn, Cu, Cr, Ni, and Pb. Preliminary phytochemical screening revealed tannins, steroids, triterpenes, saponins, alkaloids, anthraquinones, and flavonoids. The Median lethal dose (LD50) of the extract was estimated to be higher than 5000 mg/kg orally. The animals treated with the extract showed a significant (p<0.05) decrease in blood glucose levels compared to the negative control. Blood glucose levels dropped below baseline in the animals treated with the highest dose (1500 mg/ kg) of the extract. The study therefore revealed that Hymenodictyon floribundum has the potential to produce a blood glucose-lowering effect and corroborates the claim of antidiabetic activity of the plant.

Keywords

• Diabetes mellitus, OGTT, Hymenodictyon floribundum, Hyperglycemia, Blood glucose