Optimizing Hydroalcoholic Extraction of African Medicinal Plants for Enhanced α-Amylase Inhibition and Functional Enrichment of Hypoglycemic Bread Doughs

Abstract

Type 2 diabetes mellitus (T2DM) remains a global health challenge, necessitating novel therapeutic and dietary strategies. This study optimized hydroalcoholic extraction parameters to maximize α-amylase inhibitory activity from five African medicinal plants: <i>Combretum glutinosum</i> (CG), <i>Ziziphus mauritiana</i> (ZM), <i>Gymnosporia senegalensis</i> (GS), <i>Boscia senegalensis</i> (BS), and <i>Citrullus colocynthis</i> (CC). A central composite design (CCD) modeled the effects of the liquid-to-solid (L/S) ratio (5-15 mL/g) and ethanol concentration (0-100%, <i>v</i>/<i>v</i>), identifying optimal conditions at low L/S ratios (5 mL/g) and moderate-to-high ethanol concentrations (40-100%) for GS, ZM, and CG, where inhibition levels exceeded 80-98% of α-amylase activity. Extracts from CG, ZM, and GS showed the strongest inhibition (IC₅₀ values of 3.67, 9.8, and 2.25 mg/mL, respectively). Antioxidant capacities, evaluated by DPPH and FRAP assays, correlated strongly with total phenolic content (TPC), with ZM exhibiting superior DPPH (IC₅₀ = 1.94 ± 0.16 mg/mL) and FRAP (IC₅₀ = 4.34 ± 0.52 mg/mL) activities. Incorporation of optimized plant powders (3%, <i>w</i>/<i>v</i>) into bread dough significantly influenced textural and colorimetric properties. Mixture design analysis revealed that CG-rich formulations (>2%) yielding hardness exceed 6 N, while ZM-GS blends maintain 3 N, offering targeted firmness control. The addition of medicinal plants significantly increased the total phenolics content by 60% of doughs and thus caused a significant improvement in antioxidant activities. These functional enrichments suggest potential for developing hypoglycemic bakery products with improved sensory attributes. This integrative approach combining extraction optimization and food formulation offers promising avenues for natural antidiabetic agents and functional food development.