Search

In this study, structural characterization, physical property and antioxidant activity of catechin grafted Tremella fuciformis polysaccharide (catechin-g-TPS) were investigated. Crude polysaccharides were isolated from the fruit bodies of T. fuciformis and further purified on DEAE-52 and Sepharose CL-4B chromatography to afford a main purified fraction (named TPS). The molecular weight of TPS was determined as 5.82 × 10(5)Da by HPLC. Then, the free radical mediated grafting of catechin onto TPS was achieved by using a redox system. As compared with the unmodified TPS, catechin-g-TPS showed new bands within the range of 1300-1600 cm(-1) in FT-IR spectrum, and exhibited new signals at around δ 6.00 and 6.80 ppm in (1)H NMR spectrum. Thermogravimetric analysis indicated the thermal stability of catechin-g-TPS was higher than TPS. X-ray diffraction spectrum of catechin-g-TPS exhibited two sharp narrow diffraction peaks at 14.2 and 32.1°, corresponding to the crystalline peaks of catechin. Scanning electron microscopy observation revealed the surface of TPS was smooth, whereas the surface of catechin-g-TPS was much rough. These results all confirmed the successful grafting of catechin onto TPS. Moreover, catechin-g-TPS had higher 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and reducing power as compared to TPS., (Copyright © 2015 Elsevier B.V. All rights reserved.)

In this study, the antioxidant activity and hepatoprotective effect of inulin and catechin grafted inulin (catechin-g-inulin) against carbon tetrachloride (CCl4)-induced acute liver injury were investigated. Results showed that both inulin and catechin-g-inulin had moderate scavenging activity on superoxide radical, hydroxyl radical and H2O2, as well as lipid peroxidation inhibition effect. The antioxidant activity decreased in the order of Vc > catechin >catechin-g-inulin > inulin. Administration of inulin and catechin-g-inulin could significantly reduce the elevated levels of serum aspartate transaminase, alanine transaminase and alkaline phosphatase as compared to CCl4 treatment group. Moreover, inulin and catechin-g-inulin significantly increased the levels of hepatic superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione and total antioxidant capacity, whereas markedly decreased the malondialdehyde level when compared with CCl4 treatment group. Notably, catechin-g-inulin showed higher hepatoprotective effect than inulin. In addition, the hepatoprotective effect of catechin-g-inulin was comparable to positive standard of silymarin. Our results suggested that catechin-g-inulin had potent antioxidant activity and potential protective effect against CCl4-induced acute liver injury., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Hemodialysis can remove uremic solutes but this treatment induces oxidative stress in uremic patients because of hemo-incompatibility. Therefore, we hypothesised that an antioxidant dialysate (a dialysate containing antioxidant(s)) would provide antioxidant defence in uremic patients during hemodialysis. Several herbal extracts were studied and measurements of antioxidant power and stability assays indicated that epigallocatechin gallate (EGCG) was the best of those tested for use as an antioxidant dialysate (EGCG dialysate). We observed that EGCG dialysate could provide the highest level of antioxidant defence at a dialysate flow rate of 500 ml/min and a blood flow rate of 200 ml/min. In addition, some important parameters for hemodialysis were calculated for supporting the protective role of EGCG dialysate. This is the first description of the preparation of an antioxidant dialysate. We suggest that EGCG dialysate will reduce the level of oxidative stress in hemodialysis patients, leading to a decrease of complications associated with oxidative damage., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

In this study, novel chitosan (CS) based active films were developed by grafting natural phenolic antioxidant of protocatechuic acid (PA) onto chitosan backbones. The physicochemical, mechanical and antioxidant properties of three PA grafted CS (PA-g-CS) films with different grafting ratios were characterized. The transparent PA-g-CS films exhibited yellowish color with thickness ranging from 44.1 to 48.6 μm. By contrast with CS film, PA-g-CS films with medium and high grafting ratios showed decreased moisture content, water vapor permeability; however, increased water solubility and tensile strength. The barrier to UV light of CS film could be improved by grafting with PA. An increase in the total color difference was observed for PA-g-CS films, indicating PA-g-CS films were more colored. Among four kinds of films tested, PA-g-CS film with medium grafting ratio exhibited the highest tensile strength (45.7 MPa) and elongation at break (5.05%). According to thermogravimetric analysis, the maximum rates of weight loss for PA-g-CS films appeared at 291.8–294.0 °C. Antioxidant activity assays showed that PA-g-CS films had both dose-dependent and time-dependent scavenging activity on DPPH radical. Our results suggest that PA-g-CS films are expected to serve as novel antioxidant food packaging materials. [ABSTRACT FROM AUTHOR]

In this study, protocatechuic acid (PA) was grafted onto chitosan (CS) by a carbodiimide mediated cross-linking reaction. The structural characterization, physical property and antioxidant activity of PA grafted CS (PA-g-CS) was investigated. As results, three copolymers with different grafting ratios (61.64, 190.11 and 279.69 mg PAE/g) were obtained by varying the molar ratios of reaction substrates. PA-g-CS showed the same UV absorption peaks as PA at 258 and 292 nm. As compared to CS, PA-g-CS exhibited a decreased band at 1596 cm −1 and a new band at 1716 cm −1 , suggesting the formation of amide and ester linkages between PA and CS. New proton signals at δ 6.77–7⋅33 ppm were observed on 1 H NMR spectrum of PA-g-CS, assigning to the methine protons of PA. Signals at δ 150.8–116.6 ppm on 13 C NMR spectrum of PA-g-CS was assigned to the aromatic ring carbon of PA moieties. All the structural information confirmed the successful grafting of PA onto CS. SEM observation showed CS had a smooth surface, while PA- g -CS had a rough surface. TGA revealed the thermal stability of PA-g-CS was lower than CS. Antioxidant activity assays further verified the reducing power and DDPH radical scavenging activity of PA-g-CS was much higher than CS. [ABSTRACT FROM AUTHOR]