Evaluation of In Vivo Antidiabetic, In Vitro α-Amylase Inhibitory, and In Vitro Antioxidant Activity of Leaves Crude Extract and Solvent Fractions ofBersama abyssinicaFresen (Melianthaceae)

Abstract

Background. The leaves of Bersama abyssinica are used for the treatment of diabetes mellitus in folk medicine system of Ethiopia. The present study was done based on the traditional claim of B abyssinica for the treatment of diabetes mellitus. Methods. The α-amylase inhibition and antioxidant activities of B abyssinica extracts were evaluated by using 3,5-dinitrosalicylic acid method and diphenyl-2-picrylhydrazyl assay model, respectively. Blood glucose lowering activity of the extracts was studied in 4 animal models; normoglycemic, oral glucose loaded, and streptozotocin-induced diabetic mice models. Results. Among the extracts, the crude extract showed the highest α-amylase enzyme inhibition activity with an IC50 of 6.57 μg/mL. The water fraction showed the strongest antioxidant activity with an IC50 of 3.43 μg/mL. The crude extract at doses of 200, and 400 mg/kg showed significant ( P < .05) hypoglycemic activity in normoglycemic mice. All doses of the crude extract significantly ( P < .05) reduced blood glucose levels of oral glucose-loaded mice. In streptozotocin-induced diabetic mice models, both the crude and solvent fractions showed a significant ( P < .05) blood glucose lowering effect as compared with the negative control group post 8 hour treatment. Conclusion. The results demonstrated the beneficial biochemical effects of B abyssinica extract by inhibiting α-amylase and scavenging the free radicals. The crude extract and solvent fractions of B abyssinica had significant blood glucose lowering effect in all animal models.

<p>Hypoglycemic, Anti-Hyperglycemic and Anti-Hyperlipidemic Effects of <em>Bersama abyssinica Fresen</em> (Melianthaceae) Leaves’ Solvent Fractions in Normoglycemic and Streptozotocin-Induced Diabetic Mice</p>

“…In a previous study, both the crude and its solvent fractions (chloroform, ethyl acetate, and aqueous) showed a statically significant alpha-amylase inhibition activity at different tested doses. 23 This hypoglycemic effect of the solvent fractions could be because of the inactivation of the α-amylase activity. In the previous experimental study, GLC can cause hypoglycemia effect through stimulation of insulin secretion from the pancreatic β cells.…”

“…The acute oral toxicity of B. abyssinica was conducted in the previous work, 23 according to the Organization for Economic Cooperation and Development (OECD) guideline No. 425.…”

“…The animals were randomly assigned into different groups of six animals per group to perform hypoglycemic, oral glucose tolerance test, and antihyperglycemic activity test. Dose selection was based on, acute toxicity study and a previous study of the plant extract, 23 as well as pilot experiments. The middle dose was one-tenth of the limit dose, the higher dose was twice the middle dose, and the lower dose was calculated as half of the middle dose.…”

“…43 The observed activity may fairly be a due reduction of glucose absorption into the bloodstreams via inhibition of αamylase as a previous study supports the α-amylase inhibitory activity of B. abyssinica. 23 Furthermore, the observed activity might be due to other possible mechanisms such as decreased gluconeogenesis, stimulation of glycogenesis in the liver, and enhanced tissue glucose utilization. 32 The other possible anti-hyperglycemic effect of B. abyssinica on the OGTT might be due to the attendance of phytoconstituents such as flavonoids, 44 since flavonoids can regenerate pancreatic β-cells, inhibiting the glucose transporter activity from the intestine, and increasing the peripheral utilization of glucose.…”

“…17,22 Significant in vitro alpha-amylase inhibition, free radical scavenging activities, and antidiabetic activity in singledose diabetic mice, normoglycemic mice, and oral glucose loaded mice were reported in Ethiopia. 23 However, there is no previous study in the hypoglycemic, anti-hyperglycemic, and anti-hyperlipidemic effects of Bersama Abyssinica Fresen (Melianthaceae) leaves solvent fractions in normoglycemic and streptozotocin-induced diabetic mice. Thus, this study aimed to evaluate the anti-diabetic, antihyperlipidemic activity, and effect on the bodyweight of the repeated doses of the solvent fractions of Bersama abyssinica in normoglycemic and streptozotocin-induced diabetic mice.…”