Methanol-Extract/Fractions of Dacryodes edulis Leaves Ameliorate Hyperglycemia and Associated Oxidative Stress in Streptozotocin-Induced Diabetic Wistar Rats

Abstract

The present study evaluated the antidiabetic and antioxidant potential of the methanolic extract/solvent fractions of the leaves of Dacryodes edulis using a streptozotocin (STZ)-induced diabetic Albino Wistar rat model. The fasting blood glucose/insulin levels and inhibition of α-amylase and α-glucosidase were determined. Antioxidant activity was assessed in vitro by 2,2-diphenyl-1-picrylhydrazyl, hydroxyl, superoxide scavenging, reducing power, and total antioxidant capacity assays and in vivo by monitoring catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activities and reduced glutathione (GSH) and malondialdehyde (MDA) levels. The aqueous-methanol fraction exhibited the highest and significant ( P < .05) reduction in fasting blood glucose (FBG; 54.03%) with a concomitant inhibition of α-amylase and α-glucosidase activities. The ethyl acetate fraction also exhibited a significant ( P < .05) reduction in FBG and an increase in insulin levels in the treated diabetic Wistar rats. A significantly ( P < .05) higher reducing power and radical scavenging activity was observed in the aqueous-methanol and ethyl acetate fractions. The aqueous-methanol and ethyl acetate fractions also significantly ( P < .05) reversed the alterations in oxidative stress markers (GSH, MDA, CAT, and SOD) observed in the diabetic control group. In conclusion, the study demonstrated that the methanol extract of Dacryodes edulis ameliorates hyperglycemia and the associated oxidative stress in STZ-induced diabetic Wistar rats. These observed activities are largely due to the compounds that partitions into the aqueous-methanol (55:45) solvent fraction. This provides scientific evidence for the use of this plant extract in folk medicine and also a baseline data for its further characterization. Further work should be carried out to characterize the aqueous-methanol solvent fractions for the active compounds.

Toxicological study of aqueous-methanol solvent fraction of methanol extract of Dacryodes edulis leaves

“…Plants rich in saponin and tannin have been suggested to be capable of destroying red blood cells in vivo [ 18 , 36 ]. Interestingly, AMDE has been reported to be highly rich in saponins and tannins [ 19 ]. Similar findings have been reported by Ufelle et al [ 18 ] in a related study.…”

“…The aqueous-methanol fraction of methanol extract of Dacryodes edulis leaves, AMDE; causes significant decrease in eythrocytic indices; which is indicative of potential anaemic condition with prolonged administration or increase in administered doses. The plausible mechanism of action of this, could be via inhibition of the erythropoetic process in the bone marrows and cellular destruction of red blood cells (which by its very nature is quite susceptible to lytic action) by phytochemicals such as flavonoids saponins and tannins – the major bioactive classes of compounds in the leaves of Dacryodes edulis [ 19 ]. Furthermore, a similar observation was made by Prajitha and Thoppil [ 51 ] in their study.…”

“…In a previous study, the methanol extract/solvent fractions of Dacryodes edulis leaves had been characterized and shown to have significant hypoglycaemic and antioxidant activities. The aqueous-methanol solvent fraction (quite rich in phenolics, flavonoids and saponins) was reported to exhibit the most significant activity [ 19 ]; thus, this extract was chosen for this study.…”

Effect of feed supplementation of Dacryodes edulis parts’ powder as prebiotic on the growth traits, ceca microbiota and blood parameters of local chickens

“…It is noteworthy that there were slight decreases in all the blood serum parameters tested in this study on increasing each of the plant part from 05% to 1% in all cases. The decrease in glucose, cholesterol, and triglycerides absorption could be attributed to phytogenic compounds (tannins, flavonoids, and phenolic) ability to inhibit carbohydrate digestive enzymes, enhanced insulin secretion, improved sensitivity of insulin, decreased intracellular pH, and scavenging of free radical ( Ononamadu et al, 2019 ). A decrease in ALT, AST, and ALP serum levels in birds fed with diets incorporating D. edulis plant parts is a good attribute as high the parameters’ high levels in chicken indicates liver failure as well as bile disorders Biasato et al (2017) .…”

Starch-iodine assay method underestimates α-amylase inhibitory potential of antioxidative compounds and extracts

“…The reducing power (RP) assay is based on Fe (III) to Fe (II) transformation in the presence of test samples that can be monitored by measuring the formation of Perl's Prussian blue at 700 nm as described in Ononamadu et al (2019). Briefly, various concentrations (0-200 μg/ml) of the extract/fractions (2 ml) were prepared and mixed with 2 ml of phosphate buffer (0.2 M, pH 6.6) and 2 ml of potassium ferricyanide (10 mg/ml).…”