Extraction, Purification, Physicochemical Properties, and Activity of a New Polysaccharide From Cordyceps cicadae

Abstract

The polysaccharides from C. cicadae were extracted by ultrasonically-assisted enzymatic extraction (UAEE). Response surface analysis was used to determine the optimum parameters as follows: addition of enzymes, 0.71%; extraction temperature, 60°C; extraction time, 18 min; liquid-solid ratio, 46:1 (mL/g). The extraction yield of polysaccharide was 3.66 ± 0.87%. A novel polysaccharide fraction (JCH-a1) from C. cicadae was extracted and then purified by cellulose DEAE-32 and Sephadex G-100 anion exchange chromatography. The analysis results showed that the molar ratio of galactose, glucose, and mannose in JCH-a1 cells (60.7 kDa) was 0.89:1:0.39. JCH-a1 with a triple helix contains more α-glycosides and has strong thermal stability. Moreover, JCH-a1 showed strong antioxidant activity and acted as a strong inhibitor of α-glucosidase in vitro. In addition, JCH-a1 can prolong the lifespan of C. elegans. The present study might provide a basis for further study of JCH-a1 as an antioxidant and hypoglycemic food or drug.

Keywords: Cordyceps cicadae (C. cicadae); extraction; physicochemical properties; polysaccharide; purification.

FIGURE 1

Tri-dimensional response surface plots and contour plots illustrating the interaction between the different variables on the yield of JCH. ((a,A) enzymatic addition and ultrasonic temperature; (b,B) enzymatic addition and ultrasound time; (c,C) enzymatic addition and liquid-solid ratio; (d,D) ultrasonic temperature and ultrasonic time; (e,E) ultrasonic temperature and liquid-solid ratio; (f,F) ultrasonic time and liquid-solid ratio; R1, JCH yield).

FIGURE 2

(A) The crude JCH was applied to a DEAE–32 column (B) JCH-a obtained from DEAE–32 was eluted with a Superdex-G100.

FIGURE 3

(A) HPLC chromatogram of the monosaccharide standards and JCH-a1. Peaks: 1 Mannose, 2 Ribose, 3 Rhamnose, 4 Glucuronic acid, 5 Galacturonic acid, 6 N- acetyl-glucosamine, 7 Glucose, 8 N- acetyl-galactose, 9 Galactose, 10 Xylose, 11 Arabinose, 12 Fucose; (B) GPC of JCH-a1.

FIGURE 4

SEM of JCH-a1 [(A) 10 μm; (B) 5 μm]; AFM images of JCH-a1 (C,D).

FIGURE 5

Changes in the maximum absorption wavelength (λ_max) of JCH-a1/Congo red complex with various NaOH concentrations.

FIGURE 6

(A) Inhibition on the α-glucosidase activity of acarbose; (B) inhibition on the α-glucosidase activity of JCH-a1; (C) inhibition kinetic diagram of JCH-a1; (D) lineweaver-Burk plots for a-glucosidase inhibition by JCH-a1.

FIGURE 7

The OD of E. coli is reported daily for each concentration of JCH-a1.

FIGURE 8

JCH-a1 can extend the lifespan of C. elegans. (A) At 20°C, C. elegans longevity was cultured at different concentrations of JCH-a1 and survival was monitored. (B) At 20°C, the mean lifespan, median lifespan and maximum lifespan of C. elegans were cultured at different concentrations of JCH-a1. * represents significant difference (P < 0.05), and ^** represents extremely significant difference (P < 0.01).

FIGURE 9

JCH-a1 improved the health of C. elegans. (A) Survival curves of N2 with or without JCH-a1 at 37°C for heat stress. (B) Survival of N2 cultured with or without JCH-a1 in S-buffer containing 30 mM H₂O₂ for oxidative stress. (C) Survival of N2 cultured with or without JCH-a1 in S-buffer containing 300 mM NaCl for osmotic stress. (D) Survival curves of N2 with or without JCH-a1 at UV conditions for UV stress.