Optimization of ultrasound-assisted extraction of polyphenols from Mansoa alliacea flowers and evaluation of their antioxidant, anti-inflammatory-related, and digestive enzyme inhibitory activities

Background Mansoa alliacea is traditionally used to treat inflammation, infections, and metabolic disorders. However, the phytochemical and biological potential of its flowers remains poorly characterized. Purpose This study optimized ultrasound-assisted extraction (UAE) of polyphenols from M. alliacea flowers and evaluated the in vitro antioxidant, anti-inflammatory-related, and digestive enzyme inhibitory activities of the optimized extract. Methods Four extraction parameters (ethanol concentration, extraction temperature, extraction time, and solid-to-solvent ratio) were initially screened by single-factor experiments. Based on these results, three key factors (temperature, time, and ethanol concentration) were selected and further optimized using a Box–Behnken design to maximize polyphenol yield. Total polyphenol content was quantified using the Folin–Ciocalteu method. UHPLC–MS profiling was conducted for tentative phytochemical characterization. The optimized extract was evaluated for in vitro antioxidant activity (DPPH, ABTS assays), anti-inflammatory activity (protein denaturation and RBC membrane stabilization), and digestive enzyme inhibitory activities (inhibition of α -amylase and α -glucosidase). Results Optimal extraction conditions (60% ethanol, 79 °C, 15 min, 1:10 w/v) yielded 275.37 ± 1.55 mg GAE/g extract. UHPLC–MS analysis revealed nine major peaks, among which two compounds were provisionally assigned as luteolin-7-O-glucoside and luteolin-7-O-glucuronide. Compared with the unoptimized extract, the optimized extract exhibited markedly stronger in vitro biological activities, with IC 50 values of 11.88 ± 0.28 and 15.58 ± 0.33 μg/mL in DPPH and ABTS assays, respectively; 38.77 ± 0.93 μg/mL for inhibition of protein denaturation; 30.74 ± 0.18 μg/mL for RBC membrane stabilization; and 30.94 ± 0.54 and 13.32 ± 0.19 μg/mL for α-amylase and α-glucosidase inhibition, respectively. Conclusion Optimized UAE significantly enhanced polyphenol enrichment in the extract and improved the in vitro antioxidant capacity, protective effects against protein denaturation and RBC hemolysis, and carbohydrate-hydrolyzing enzyme inhibitory activities of M. alliacea flower extract. These findings provide preliminary scientific support for the traditional use of M. alliacea and suggest that its polyphenol-rich extract may serve as a promising candidate for further investigation as a functional or phytopharmaceutical ingredient.