Maerua angolensis is a shrub or small tree widely distributed in tropical Africa. The plant materials are used for various ethnomedicinal applications across the region, including the prevention and treatment of diabetes. This study was aimed to evaluate the antidiabetic potential of formulated freeze-dried aqueous extract of Maerua angolensis leaves using standard in vitro and in vivo experimental models. Infusion extract of the plant’s powdered dried leaves was prepared, the resultant extract was freeze-dried and formulated (denoted FIEMa). The physicochemical, quantitative and qualitative phytochemical constituents of FIEMa were determined using analytical techniques (UV-visible and HPLC). The antidiabetic activity of the reconstituted formulation was investigated using in vitro and in vivo models. The in vitro activity was assessed using Phosphomolybdenum assay and DPPH (2,2-Diphenyl-1-picrylhydrazyl) radical scavenging activity for antioxidant effect, and α-amylase inhibition and α- glycosidase inhibition assays. The assays of the normoglycemic, oral glucose load tolerance, and single-dose alloxan (150 mg/kg) induced diabetes in rats were used for in vivo antidiabetic activity. The results show that FIEMa contains valuable phytochemicals. It exhibited antioxidant effect, α-amylase and α- glucosidase inhibition activities. FIEMa did not significantly reduce blood glucose levels (BGL) in normoglycemic mice but produced a significant reduction of BGL in the oral glucose tolerance test. In alloxan-induced diabetic rats, significant reductions of BGL were observed in groups treated with high doses of FIEMa in the single-dose study and from the second week onwards in the repeated dose study. It also exhibited less reduction in body weight compared to the control group. The findings indicate that FIEMa has an antidiabetic activity, low risk of hypoglycemia, and body weight loss. The valuable phytochemicals plausibly mediate this effect, especially the dominant betulinic acid detected in FIEMa, most likely acting in synergy.

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