Optimization of synchronous extraction of polysaccharides and polyphenols from Brasenia schreberi via ultrasonic-assisted aqueous two-phase system: Modeling, structural characterization, and antioxidant properties

Ultrasonic-assisted aqueous two-phase extraction (UA-ATPE) system was utilized to simultaneously extract polysaccharides (BPs) and polyphenols (BPp) from Brasenia schreberi employing a biphasic solvent system composed of ethanol and (NH 4 ) 2 SO 4 . The optimization of UA-ATPE was conducted using response surface methodology, guided by the findings from single-factor experiments. The optimal parameters identified were as follows: ultrasonic temperature of 66°C, ultrasonic extraction time of 33 min, and liquid-solid ratio of 84 mL/g. The yields of BPs and BPp were determined to be 5.39% and 12.53%, respectively. Through the processes of separation and purification, a novel polysaccharide designated as BPs-1 (872.19 kDa) was successfully obtained. BPs-1 is a type of heteropolysaccharide, primarily composed of monosaccharides such as galactose, fucose, arabinose, xylose, and mannose. The main chain of BPs-1 is predominantly composed of →3)-β-Gal p -(1→, →2,3,6)-β-Gal p -(1→, →2,3)-α-Man p -(1→, and →2,3,6)-α-Man p -(1→. Meanwhile, high-purity polyphenols (purified BPp) were achieved through the use of HP10 macroporous resin. Through UHPLC-ESI-QTOF-MS/MS, a total of 76 phenolic compounds were identified in the purified polyphenols, including 8 kinds of phenolic acids, 23 kinds of flavonoids, and 45 kinds of hydrolyzable tannins. The HPLC quantitative analysis results revealed that the contents of kaempferol 3-O-(6''-galloyl)-glucoside and ethyl gallate in the purified polyphenols are relatively high, at 205.7 mg/g and 117.88 mg/g, respectively. Additionally, BPs-1 and purified BPp both demonstrated significant ABTS and DPPH free radical scavenging capabilities, exhibiting excellent antioxidant effects. This research establishes a foundational theory for the comprehensive utilization of polysaccharides and polyphenols from B. schreberi in the food and pharmaceutical industries. • Synchronous extraction process of BPs and BPp using UA-ATPE has been optimized. • The structural characteristics of BPs-1 have been preliminarily characterized. • The chemical compositions of purified BPp have been identified. • BPs-1 and purified BPp exhibit antioxidant activity.