Carboxymethylation and acetylation of the polysaccharide from Cordyceps militaris and their α-glucosidase inhibitory activities

Abstract

The crude polysaccharide extracted from Cordyceps militaris was chemically modified to obtain carboxymethylated derivatives (CM-CPS) and acetylated derivatives (AC-CPS). The physicochemical characterizations were comparatively investigated by chemical methods, high-performance gel permeation chromatography, FT-IR spectra, NMR analysis, Congo red test, scanning electron microscopy, atomic force microscopy and differential scanning calorimetry. Then α-glucosidase inhibitory activities were conducted to determine the structure-bioactivity relationship. Results indicated that carboxymethylation and acetylation modification of polysaccharide were successful with the carboxymethyl substitutions might being C-6, C-2 and acetyl substitutions at C-3, C-6 inferred from NMR analysis. In addition, the tertiary structure, ultrastructure, melting properties were also different from native polysaccharide. Besides, α-glucosidase inhibitory activities of derivatives exhibited differently with CM-CPS to be the lowest. Therefore, it was concluded that change of structure in polysaccharide had certain effect on bioactivity with degree of substitution and substituents position being the influence factors.

Preparation, characterization and antioxidant activity of acetylated garlic polysaccharide, and garlic polysaccharide‐Zn (II) complex

“…As shown in Figure 3, the peak of chemical shift 100–105 ppm belonged to C1, which is shown that the glycosidic bonds are β‐glycosidic bonds, and consistent with the results of 1 H NMR, the peaks at 70–80 ppm were C2, C3, and C5, the peaks at 65–60 ppm were C4 and C6 1,16 . There is no signal in low field from 160 ppm to 180 ppm, which indicates that PS did not contain uronic acid, which was in accordance with the result of IR spectrum 15 …”

“…The C1 proton signals of α‐type pyranose were more than 5.0 ppm, β‐type is less than 5.0 ppm, so the two types can be distinguished 22 . It was showed in Figure 2 that almost all the signals of proton appeared in the region of δ 3.4–4.4 ppm, which were the typical signals of PS 15 . It belongs to fructan and its glycoside bond is linked by β‐glycoside bond.…”

“…For PS (Figure 1(a)), the stretching vibration band of 3368 cm −1 hydroxyl (O─H), 2935 cm −1 methylene (C─H), 1634 cm −1 hydroxyl (OH) rotational vibration, 1129 cm −1 intermediate alcohol group (O─H) shear vibration band, 1025 cm −1 glycosyl ring (C─O─C) stretching vibration band, 934 cm −1 fructofuranose ring symmetry stretching vibration band, and 817 cm −1 shearing vibration band of fruit furanose methylene (C─H) 1,3 . Among them, 1129 and 1025 cm −1 are the characteristic absorption bands of ketal characteristic group (C─O─C─O─C), 14,15 and 934 and 817 cm −1 are the related absorption bands of fructan 11…”

“…After acetylation, the acetylmethyl proton peak at δ 2.2 ppm high field can be used to determine the success of acetylation modification ( 15,20 ).…”

Inhibition of Calcium Oxalate Formation and Antioxidant Activity of Carboxymethylated Poria cocos Polysaccharides

“…Polysaccharides (PCP-C0) 2.2.1. Carboxymethylation of PCP-C0 [23][24][25]. 300 mg PCP-C0 was suspended in 15 mL of isopropanol, stirred at room temperature for 15 min, slowly added 10 mL of 30% NaOH solution, stirred at 50°C water bath for 1 h, then added 2.63 g of monochloroacetic acid, and then heated at 60°C for 2 h. After cooling to room temperature, adjust to neutrality with 0.5 mol/L HCl, dialyze with distilled water (Mw retention 3000 Da) for 3 days, and concentrate and freezedry to obtain carboxymethylated polysaccharides (PCP-Cs) with different degrees of substitution.…”