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. 2023 May 4;28(9):3880.
doi: 10.3390/molecules28093880.

Ultrasound-Microwave Combined Extraction of Novel Polysaccharide Fractions from Lycium barbarum Leaves and Their In Vitro Hypoglycemic and Antioxidant Activities

Na Quan  1 , Yi-Dan Wang  1 , Guo-Rong Li  2 , Zi-Qi Liu  1 , Jing Feng  3 , Chun-Lei Qiao  1 , Hua-Feng Zhang  1
Affiliations

Ultrasound-Microwave Combined Extraction of Novel Polysaccharide Fractions from Lycium barbarum Leaves and Their In Vitro Hypoglycemic and Antioxidant Activities

Na Quan et al. Molecules. .

Abstract

Ultrasound-microwave combined extraction (UMCE), gradient ethanol precipitation, chemical characterization, and antioxidant and hypoglycemic activities of Lycium barbarum leaf polysaccharides (LLP) were systematically studied. The optimal conditions for UMCE of LLP achieved by response surface method (RSM) were as follows: microwave time of 16 min, ultrasonic time of 20 min, particle size of 100 mesh, and ratio of liquid to solid of 55:1. Three novel polysaccharide fractions (LLP30, LLP50, LLP70) with different molecular weights were obtained by gradient ethanol precipitation. Polysaccharide samples exhibited scavenging capacities against ABTS and DPPH radicals and inhibitory activities against α-glucosidase and α-amylase. Among the three fractions, LLP30 possessed relatively high antioxidant and hypoglycemic activities in vitro, which showed a potential for becoming a nutraceutical or a phytopharmaceutical for prevention and treatment of hyperglycemia or diabetes.

Keywords: Lycium barbarum leaves; antioxidant capacity; hypoglycemic activity; polysaccharides; ultrasound–microwave combined extraction.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Effects of microwave time (a), ultrasonic time (b), particle size (c), and ratio of liquid to solid (d) on extraction yield of LLP.
Figure 2
Figure 2
Response surface plots of ultrasound–microwave combined extraction. (a) microwave time versus ultrasonic time; (b) microwave time versus particle size; (c) microwave time versus ratio of liquid to solid; (d) ultrasonic time versus particle size; (e) ultrasonic time versus ratio of liquid to solid; (f) particle size versus ratio of liquid to solid.
Figure 2
Figure 2
Response surface plots of ultrasound–microwave combined extraction. (a) microwave time versus ultrasonic time; (b) microwave time versus particle size; (c) microwave time versus ratio of liquid to solid; (d) ultrasonic time versus particle size; (e) ultrasonic time versus ratio of liquid to solid; (f) particle size versus ratio of liquid to solid.
Figure 3
Figure 3
Contour plots of ultrasound–microwave combined extraction. (a) microwave time versus ultrasonic time; (b) microwave time versus particle size; (c) microwave time versus ratio of liquid to solid; (d) ultrasonic time versus particle size; (e) ultrasonic time versus ratio of liquid to solid; (f) particle size versus ratio of liquid to solid.
Figure 3
Figure 3
Contour plots of ultrasound–microwave combined extraction. (a) microwave time versus ultrasonic time; (b) microwave time versus particle size; (c) microwave time versus ratio of liquid to solid; (d) ultrasonic time versus particle size; (e) ultrasonic time versus ratio of liquid to solid; (f) particle size versus ratio of liquid to solid.
Figure 4
Figure 4
Viscosity-average molecular weights of LLP.
Figure 5
Figure 5
Antioxidant activities of polysaccharides extracted from Lycium barbarum leaves. (A) ABTS assay; (B) DPPH assay.
Figure 6
Figure 6
In vitro hypoglycemic activities of polysaccharides extracted from Lycium barbarum leaves. (A) α-glucosidase; (B) α-amylase.
See this image and copyright information in PMC

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