Inhibitory effects of solvent-partitioned fractions of two nigerian herbs (Spondias mombin Linn. and mangifera indica L.) on α-amylase and α-glucosidase

Therapies directed towards controlling hyperglycemia, the hallmark of type-2 diabetes mellitus, go a long way in managing diabetes and its related complications. Reducing glucose level through the inhibition of the relevant carbohydrate hydrolyzing enzymes is one among many routes in the management of diabetes. This study investigates the in vitro enzyme inhibitory and antioxidant properties of solvent-partitioned fractions of Spondias mombin and Mangifera indica leaves; which are used extensively in the treatment of diabetic patients locally. The leaves of S. mombin and M. indica were extracted with methanol and fractionated to obtain n-hexane (HF), ethyl acetate (EAF), n-butanol (BF), and aqueous (AF) fractions successively. The α-amylase and α-glucosidase inhibitory activities of fractions of S. mombin and M. indica leaves were investigated while the antioxidant activity of each fraction was analyzed using iron chelating and ABTS (2,2′-azino-bis(3-ethylbenzothiazoline)-6-sulphonic acid) radical scavenging assay. Our findings indicated that the ethyl acetate fraction of M. indica leaves contained a considerably higher (p < 0.05) amount of total phenolic, flavonoids, metal ion, and ABTS radical scavenging activity than the ethyl acetate fractions of S. mombin. Furthermore, the ethyl acetate fraction of M. indica had a considerably higher (p < 0.05) inhibitory effect on α-glucosidase (IC₅₀ = 25.11 ± 0.01 μg mL⁻¹), and α-amylase (IC₅₀ = 24.04 ± 0.12 μg mL⁻¹) activities than the S. mombin fraction. Hence, the inhibitory activities of S. mombin and M. indica leaves suggest that they are a potential source of orally active antidiabetic agents and could be employed to formulate new plant-based pharmaceutical and nutraceutical drugs to improve human health.