A New Method of Extracting Polygonatum sibiricum Polysaccharide with Antioxidant Function: Ultrasound-Assisted Extraction-Deep Eutectic Solvents Method

Abstract

Polygonatum sibiricum Polysaccharide (PsP) with antioxidant function is the main active component of Polygonatum sibiricum (P.sibiricum). The currently poor extraction yield and extraction methods of PsP cannot meet the application of that in food industrial production. In this research, an ultrasound-assisted extraction-deep eutectic solvents (UAE-DESs) method, which has never been used in the PsP industry, was first used to extract PsP. The extraction conditions were optimized by the response surface method (RSM). Both the extraction yield and antioxidant function were simultaneously considered during the optimization process. The indicators of PsP’s level and antioxidant activity in vitro were used to present the extraction yield of the UAE-DESs method, the purity, and the antioxidant effect of PsP. Under the optimal conditions, which included a liquid–solid ratio of 26:1 (mL:g), extraction temperature of 80 °C, ultrasonic time of 51 min, and ultrasonic power of 82 W, the PsP extraction yield could reach (43.61 ± 0.09)%, which was obviously higher than single DESs (33.81%) and UAE (5.83%), respectively, and the PsP appeared favorably antioxidant function. This research proposed an efficient extraction method for PsP, filled the basic research gap, and further improved the development of PsP as a dietary supplement with antioxidant function in the food industry.

Comparison of Polygonatum sibiricum Polysaccharides Found in Young and Mature Rhizomes

“…The distinction between young and mature rhizomes was conducted according to Li et al [23], and the practical experience of our team in previous research. The PsP extraction was carried out by using the ultrasound-assisted extraction-deep eutectic solvents (UAE-DESs) method, which our team has employed in previous studies [24].…”

“…Then, anhydrous ethanol was added into the centrifuge tube at a liquid-to-mixture ratio of 4:1. After the sample was processed by alcohol precipitation at 4 °C for 12 h, PsP was collected by using centrifugation at 5000 rpm for 15 min [24,28].…”

“…The PsP content was determined by employing 0.2% anthrone-sulfuric acid reagent according to a procedure described by Sun et al [24]. The 100 µL PsP extract was added into 1.9 mL distilled water, then 8 mL of 0.2% anthrone-sulfuric acid solution was added into them.…”

“…The content of protein was determined by Coomassie brilliant blue test procedure described by Sun et al [24]. Before adding 5 mL Coomassie brilliant blue test solution, 100 µL of the extract was added to 0.9 mL of distilled water.…”

“…The DPPH free radical scavenging ability was evaluated by the method described by Sun et al [24], which existed small modifications. First, an 80 µmol/L DPPH methanol solution was prepared and stored away from light.…”