Phytochemical Screening, Quantitative Bioactive Estimation, and α-Amylase Inhibitory Activity of Eleusine coracana, Pennisetum glaucum, and Setaria italica Hydro-Methanolic Extracts

Research Article

Abstract

Persistent postprandial hyperglycemia is a primary therapeutic target in the management of type 2 diabetes mellitus. This study evaluates the botanical secondary metabolites and in-vitro carbohydrate-hydrolyzing enzyme inhibitory potential of hydro-methanolic grain extracts of three different millets namely finger millet (Eleusine coracana), pearl millet (Pennisetum glaucum), and foxtail millet (Setaria italica). Qualitative phytochemical screening showed the presence of glycosides, saponins, tannins, flavonoids, alkaloids, and phenolic compounds across all species. To establish a quantitative correlation with bioactivity, spectrophotometric assays were executed to determine the total phenolic content (TPC) and total flavonoid content (TFC). Eleusine coracana showed the highest concentration of polyphenolics (45.21 ± 1.12 mg Gallic Acid Equivalents/g dry extract) and flavonoids (12.43 ± 0.45 mg Quercetin Equivalents/g dry extract), followed by Setaria italica and Pennisetum glaucum. In the porcine pancreatic α-amylase inhibition assay, the extracts displayed concentration-dependent enzyme inhibition within a range of 100 to 500 µg/mL. Eleusine coracana showed the most potent enzymatic modulation with an IC50 value of 346.57 ± 4.82 µg/mL, compared to 472.18 ± 5.91 µg/mL for Setaria italica and 528.64 ± 7.14 µg/mL for Pennisetum glaucum. The reference drug acarbose exhibited an IC50 of 64.12 ± 1.84 µg/mL. The moderate, concentration-dependent inhibition profiles of these crude extracts suggest specific active-site or allosteric interactions rather than non-specific protein precipitation. These results support the utilization of these millet species as functional dietary supplements to attenuate starch digestion and manage postprandial glucose excursions