Ultrasound-assisted Aqueous Two-Phase Extraction of Flavonoids and Polysaccharides from Heracleum moellendorffii: Preparation of Microemulsion and Evaluation of Its in Vitro Hypoglycemic and Hypolipidemic Activities

Heracleum moellendorffii contains abundant bioactive components such as flavonoids and polysaccharides. However, their efficient extraction and utilization face challenges. This study aimed to develop an efficient ultrasound-assisted aqueous two-phase extraction technique for the simultaneous extraction of flavonoids and polysaccharides from Heracleum moellendorffii. The extracted flavonoids and polysaccharides were formulated into an oil-in-water microemulsion to enhance the in vitro hypoglycemic and hypolipidemic activities of Heracleum moellendorffii, thereby providing a novel approach for the high-value utilization of Heracleum moellendorffii. First, the phase diagram of the polyethylene glycol-ammonium sulfate aqueous two-phase system was plotted using the cloud point method to identify the suitable biphasic region. Key factors influencing extraction efficiency were screened through single-factor experiments and Plackett-Burman tests, and then the extraction process was further optimized using Box-Behnken response surface methodology. The optimal conditions as follows: Liquid-to-material ratio of 34.5:1 mL/g, ultrasonic time of 41 min, and extraction temperature of 51 ℃. Under these conditions, the extraction yields of flavonoids and polysaccharides were 0.54% and 10.03%, respectively. The extracts were purified and used to prepare the Heracleum moellendorffii flavonoid-polysaccharide oil-in-water microemulsion. The resulting microemulsion appeared as a pale yellow, clear, and transparent liquid with an average particle size of 140.80 nm, a Zeta potential of −19.36 mV, and a flavonoid encapsulation efficiency of 85.31%. In vitro activity results indicated that the Heracleum moellendorffii flavonoid-polysaccharide microemulsion showed sodium glycocholate and sodium taurocholate binding rates of 59.92% and 56.91%, respectively, along with a pancreatic lipase inhibition rate of 78.89%, demonstrating promising potential for lipid-lowering effects. Furthermore, this microemulsion exhibited good inhibitory activity against α-glucosidase and α-amylase, with IC₅₀ values of 13.61 mg/mL and 12.69 mg/mL, respectively. This study provides a theoretical foundation and technical support for the efficient utilization of active components from Heracleum moellendorffii and the development of functional foods.