Zhongqin Chen

A novel cross-linked enzyme aggregates (CLEAs) of papain and neutrase-production, partial characterization and application

The neutrase (EC 3.4.24.4) and papain (EC 3.4.22.2) were together immobilized ascross-linked enzyme aggregates (N-P-CLEAs) and their properties were characterized. The influence of the precipitant, cross-linking ratio of glutaraldehyde and cross-linking time were investigated. Ethanol was selected as the more efficient precipitant compared with ammonium sulfate. The proper cross-linking ratio of enzyme and glutaraldehyde was 1:5 (v/v) and the optimized cross-linking time was 4h. N-P-CLEAs showed obvious improvement in thermal stability and pH stability than the free enzyme (P<0.05) and could hold relatively high activity retention in nonpolar and hydrophilic solvents and without activity loss at 4°C for more than six months. The cross-linking reaction had been appeared in N-P-CLEAs and more orderly microscopic surface morphology of N-P-CLEAs was observed. The molecular weight and thermal denaturation temperature of N-P-CLEAs were increased while the isoelectric point was decreased compared with those of the free enzymes. Application of N-P-CLEAs in bean proteins and zein showed a higher degree of hydrolysis, such as the hydrolysis degree of mung bean protein hydrolyzed by N-P-CLEAs was 12%, increased by approximately 4.5% compared to that of free enzyme. The results demonstrated that the N-P-CLEAs was suitable for application in food protein hydrolysis.

Physicochemical characterization of the oolong tea polysaccharides with high molecular weight and their synergistic effects in combination with polyphenols on hepatocellular carcinoma

This study was to investigate the synergistic effects of polysaccharides with the molecular weight more than 80kDa (OTPS1) and polyphenols (OTP) isolated from oolong tea on hepatocellular carcinoma (HCC) in vitro and in vivo. The physicochemical properties of OTPS fractions were characterized. The synergistic effects of OTPS1 and OTP were evaluated based on the combination index (CI). Results showed that the highest uronic acid contents (32.96%) and viscosity (239.56mLg-1), multicavity structure of OTPS1 were contributed to the synergistic effects with OTP (52.17% content of epigallocatechin-3-gallate (EGCG)). OTPS1 and OTP showed the strongest synergism ability on SMMC7721 cells (CI<0.2). Co-administrated with OTPS1 and OTP exhibited the synergistic effects on the tumor proliferation and growth with the CI values of 0.34 and 0.39, respectively. Antioxidative and immune levels of the mice were obviously increased after combination administration. These results suggested that OTPS1 in combination with OTP might be functional supplements for the treatment of HCC.

Effects of simulated gastrointestinal digestion in vitro on the chemical properties, antioxidant activity, α-amylase and α-glucosidase inhibitory activity of polysaccharides from Inonotus obliquus

This study was aimed to investigate the impacts of gastrointestinal digestion in vitro on the physicochemical properties and the biological activities of polysaccharides from Inonotus obliquus (UIOPS-1). Results showed that the monosaccharides composition, structure and conformation of polysaccharides were remarkably altered, and the molecular weight (Mw) of UIOPS-1 was steadily decreased from 105.02kDa to 88.97kDa and 36.74kDa after simulated digestion. The reducing ends were increased and the free monosaccharides including d-glucose, d-galactose and d-xylose were released suggested that the degradation of UIOPS-1 was caused by disrupting the aggregates and glycosidic bonds. The antioxidant activities of UIOPS-1 were significantly increased after gastric digestion (P<0.05), however, they were decreased after intestinal digestion. The α-amylase and α-glucosidase inhibitory activities of UIOPS-1 were significantly increased after digestion indicating a good control of postprandial hyperglycemia (P<0.001). The results indicated that UIOPS-1 still exhibited antioxidant and antihyperglycemic potential after gastrointestinal digestion, which could be considered as a promising candidate for functional foods.

Preparation, Characterization and Application of Polysaccharide-Based Metallic Nanoparticles: A Review

Polysaccharides are natural biopolymers that have been recognized to be the most promising hosts for the synthesis of metallic nanoparticles (MNPs) because of their outstanding biocompatible and biodegradable properties. Polysaccharides are diverse in size and molecular chains, making them suitable for the reduction and stabilization of MNPs. Considerable research has been directed toward investigating polysaccharide-based metallic nanoparticles (PMNPs) through host–guest strategy. In this review, approaches of preparation, including top-down and bottom-up approaches, are presented and compared. Different characterization techniques such as scanning electron microscopy, transmission electron microscopy, dynamic light scattering, UV-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction and small-angle X-ray scattering are discussed in detail. Besides, the applications of PMNPs in the field of wound healing, targeted delivery, biosensing, catalysis and agents with antimicrobial, antiviral and anticancer capabilities are specifically highlighted. The controversial toxicological effects of PMNPs are also discussed. This review can provide significant insights into the utilization of polysaccharides as the hosts to synthesize MPNs and facilitate their further development in synthesis approaches, characterization techniques as well as potential applications.

Effects of polysaccharides from Inonotus obliquus and its chromium (III) complex on advanced glycation end-products formation, α-amylase, α-glucosidase activity and H2O2-induced oxidative damage in hepatic L02 cells

In the present study, the antioxidant activity, anti-glycation activity, α-amylase, α-glucosidase inhibitory activity of polysaccharides from Inonotus obliquus (UIOPS) and its chromium (III) complex (UIOPC) were investigated. Their protective effects against H2O2-induced oxidative damages in hepatic L02 cells were also assessed. Results demonstrated that UIOPC and UIOPS exhibited remarkable DPPH scavenging activity, ferric reducing power and hemolysis inhibitory activity. UIOPC also showed significant inhibitory capacity on α-amylase and α-glucosidase than UIOPS (P < 0.05), suggesting a good regulation of the postprandial hyperglycemia. Three phases of advanced glycation end products (AGEs) formation were effectively inhibited by UIOPC and UIOPS. Moreover, pretreatment with UIOPC and UIOPS markedly attenuated the oxidative damage induced by H2O2 in hepatic L02 cells via enhancing the cell viability, inhibiting the morphology alteration and maintaining the integrity of mitochondria. These results indicated that the anti-diabetic mechanism of UIOPC might involve in the homoeostasis of blood glucose and the recovery of endogenous antioxidant system. The elucidation of the potential anti-diabetic mechanism will facilitate the further study and application of the polysaccharides-metal complex in the functional food industry.

Hypoglycemic effects of polysaccharides from corn silk (Maydis stigma) and their beneficial roles via regulating the PI3K/Akt signaling pathway in L6 skeletal muscle myotubes

In the present study, the physicochemical properties of polysaccharides from corn silk (CSP) with different molecular weights were characterized and their inhibitory actions against α-glucosidase and α-amylase were evaluated. Then their effects on glucose uptake and mechanism of action in PI3K/Akt signaling pathway were also determined in L6 skeletal muscle cells. Results demonstrated that CSP could significantly inhibit α-amylase and α-glucosidase. CSP were non-toxic and they considerably increased the 2-NBDG uptake (P < 0.05) in L6 cells. Additionally, CSP regulated the PI3K/Akt signaling pathway and promoted the translocation of GLUT4 to the plasma membrane that would enhanced the glucose uptake in rat L6 skeletal muscle cells. Among the tested polysaccharides, CSP2 with the molecular weight of 62.16 kDa exerted appreciable hypoglycemic activity. Altogether it was suggested that CSP could be the promising candidate in the treatment of Type 2 Diabetes Mellitus (T2DM). The elucidation of the potential anti-diabetic mechanism of the polysaccharides from corn silk will facilitate their utilization in the functional food industries.

Physicochemical properties of polysaccharides from Lentinus edodes under high pressure cooking treatment and its enhanced anticancer effects

This study was to investigate the physicochemical properties and anticancer effects of polysaccharides from Lentinus edodes extracted under high pressure cooking treatment (HPLPS) in vitro and in vivo. The extraction efficiency was improved. The main molecular weight of HPLPS was about 540 and about 227 kDa. And the inhibitory effects on HepG2 and HeLa cells of HPLPS were significantly increased (p < 0.05). The in vivo anticancer effect on H22 tumor bearing mice model was evaluated. The tumor growth inhibitory rate of HPLPS-H was 67.66%. The activities of ALT and AST were decreased. The activities of SOD, CAT, GSH-Px were notably increased. The expressions of IL-2 and TNF-α were increased while the expression of VEGF was decreased. These results suggested that high pressure-assisted extracted polysaccharides from Lentinus edodes might be effectively used for the treatment of hepatocellular carcinoma through its antioxidant and immunomodulatory effects.

Preparation and characterization of a novel nanocomposite with double enzymes immobilized on magnetic Fe 3 O 4 -chitosan-sodium tripolyphosphate

In this study, a novel and efficient synchronously immobilization of double enzymes (DE, alcalase and trypsin) were developed by using the chitosan and sodium tripolyphosphate-coated magnetic nanoparticles (Fe3O4@CS-TPP) as support. The physicochemical properties of DE-Fe3O4@CS-TPP NPs were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and magnetic measurements. The preparation conditions and stabilities were also optimized and assessed. Results showed that the optimum preparation conditions were as follows: ratio of alcalase and trypsin of 3:1, enzyme concentration of 6% (w/w), temperature of 50 °C and pH of 9.0, the enzyme concentration absorbed by Fe3O4@CS-TPP NPs of 6 mg mL-1, immoblization time of 4 h, and glutaraldehyde content of 3% (w/w). The Km and Vmax values were determined as 0.5035 mg mL-1, 6.900 mg mL-1 min-1 for the immobilized enzymes, respectively. DE-Fe3O4@CS-TPP NPs was more stable than the free enzyme above 40 °C. The activity of DE-Fe3O4@CS-TPP NPs was preserved 86% after 35 days storage and retained more than 60% of its initial activity after ten times of successive reuse. Application of DE-Fe3O4@CS-TPP NPs in various protein hydrolysis showed favorable degrees of hydrolysis, yields and antioxidant activity. The results demonstrated that the DE-Fe3O4@CS-TPP NPs were suitable for application in food protein hydrolysis.