Phytochemistry and In Vitro Bioactivities of Elaeagnus angustifolia L. Leaves: Influence of Solvent Polarity, Antioxidant Properties, and α-Amylase Inhibition

This study investigated the effect of solvent polarity on extraction yield, phytochemical composition, antioxidant activity, and α-amylase inhibition of Elaeagnus angustifolia L. leaf extracts to evaluate their antidiabetic potential. Extraction yields varied with solvent polarity, with the hydroethanolic extract showing the highest (18.00%) and n-hexane the lowest (0.05%) yield. The n-butanol and ethyl acetate fractions contained the most phenolics (309.05 and 290.97 mg GAE/g), ethyl acetate was the richest in flavonoids (102.11 mg QE/g), and tannins were concentrated in dichloromethane (66.24 mg CE/g). HPLC revealed solvent-specific profiles: rutin and gallic acid dominated in n-butanol, quercetin in ethyl acetate, and 4-hydroxybenzoic and ferulic acids in dichloromethane, while chicoric acid appeared in hydroethanolic and n-hexane extracts. Antioxidant assays (DPPH, ABTS, and FRAP) showed strong activity in polar extracts, particularly hydroethanolic and ethyl acetate fractions. The n-hexane extract exhibited the highest α-amylase inhibition (IC50 = 36.70 µg/mL), surpassing acarbose (IC50 = 126.14 µg/mL), while other fractions were inactive (IC50 > 400 µg/mL). Molecular docking highlighted rutin, chlorogenic acid, and chicoric acid as potential enzyme binders. These findings demonstrate the chemical diversity and significant bioactivities of E. angustifolia leaves, supporting their potential as natural antidiabetic agents.