Anti-hyperglycaemic Effects of the Ashes of Some Nigerian Anti-diabetic Ethnomedicinal Plants

Aims: To evaluate blood glucose-lowering ability of leaf ashes and compare anti-hyperglycaemic activities of Annona muricata leaf extract and ash.

Study Design: Ashes and extract of medicinal plants were assayed using glucose-loaded rats model.

Place and Duration of Study: Department of Pharmacognosy, Obafemi Awolowo University, Ile-Ife, Nigeria, between March 2017 and February 2020.

Methodology: Adequately prepared ashes of seven plants and A. muricata methanol extract were assayed for anti-hyperglycaemic potentials, using glucose-loaded (10 g/kg, p.o.) Wistar rats that were hyperglycaemic [blood glucose levels ≥ 7.0 mmol/L] thirty minutes thereafter (T0.0). Groups of 5 rats each, were administered 100, 150, 200 mg/kg of different ashes and A. muricata extract (200 mg/kg). Normal saline and glibenclamide (5 mg/kg) were negative and positive controls, respectively. Their blood glucose levels were determined at 0-4 hours post-extract/ash/drug administration; results analysed using ANOVA followed by the Student-Newman-Keuls’ and Dunnett post-hoc tests. P ˂ .05 was considered significantly different.

Results: 100 mg/kg of Momordica charantia, Azadirachta indica and Eugenia malaccensis leaf ashes was their most active dose, indicating significantly higher extrapancreatic activity. 32, 37, 54, 59 and 36, 43, 50, 48 % reductions elicited by Chromolaena odorata (COLA) and A. muricata (AMLA) ashes (200 mg/kg) at 0.5, 1, 2 and 4 hours, respectively made them the most active ashes. Also, blood glucose levels in glibenclamide (5 mg/kg)-, COLA-, AMLA- and its extract (200 mg/kg)-treated rats were comparable (P > .05) and their anti-hyperglycaemic activity was suggested to be due to the pancreatic (insulinotropic) and extra-pancreatic actions of their constituents.

Conclusion: Study justified anti-diabetic ethnomedicinal use of plant-ashes in Nigeria, while doses were recommended for the optimum folkloric usage of these leaf ashes in managing diabetes in the rural areas of Nigeria. The leaf ashes may contain elements with glucose postprandial tolerance factor and insulin stimulating properties.