Effects of konjac glucomannan on the water distribution of frozen dough and corresponding steamed bread quality.

The influences of konjac glucomannan (KGM) on the water distribution of frozen dough and steamed bread quaility made from frozen dough were addressed in this study. Low Field Nuclear Magnetic Resonance (LF-NMR) analysis demonstrated that the less tightly bound water of the dough was transferred to tightly bound water with the increase of KGM. Differential Scanning Calorimetry (DSC) showed that the freezable water of the frozen dough was transferred to non-freezable water with increasing the amount of KGM. DSC and LF-NMR results indicated the water state in the frozen dough was consistent. The addition of KGM enhanced the height and whiteness of steamed bread, but it decreased springiness, cohesiveness and resilience of steamed bread. As the KGM substitution rate increased, the hardness of steamed bread first decreased and then increased. The steamed bread with 1.5% of KGM showed the best quality.

Interaction mechanism of aloe-emodin with trypsin: molecular structure-affinity relationship and effect on biological activities.

The molecular mechanism of interaction between aloe-emodin (AE) and trypsin was investigated, exhibiting remarkable outcomes. To detect the interaction mechanism, the binding of AE with trypsin was examined by a multi-spectroscopy and molecular docking method. Results showed that the binding of AE and trypsin would lead to static quenching and their binding forces were van der Waals forces and hydrogen bonding. The results of simultaneous and three-dimensional fluorescence spectroscopy showed that the combination of AE and trypsin caused changes in the microenvironment around the trypsin fluorophore, which might change the spatial structure of trypsin. FT-IR spectroscopy showed that the contents of α-helix and ß-turn in trypsin were decreased and the contents of ß-sheet, random coil and antiparallel ß-sheet were increased. Moreover, all these experimental results were verified and reasonably explained by molecular docking results. We also investigated the enzyme activity of trypsin and the antioxidant activity of AE. The results showed that both the enzyme activity of trypsin and the antioxidant activity of AE were decreased after interaction between AE and trypsin. The findings outlined in this study should elucidate the molecular mechanisms of interaction between AE and trypsin and contribute to making full use of AE in the food industry.

Extraction optimization, characterization and immunity activity of polysaccharides from Fructus Jujubae.

The versatile Fructus Jujubae is widely used in Chinese and Korean traditional medicine. In this study, the extraction optimization, characterization and immunostimulatory activities of polysaccharides from Fructus Jujubae were investigated. Based on a four-variable-three-level Box-Behnken statistical design, the optimal extraction parameters were optimized as follows: extraction temperature 90 °C, extraction time 3.23 h, water to raw material ratio 33:1 and extraction 3 times. Under these conditions, the experimental yield of polysaccharides was 6.47 ± 0.26%, which was close to the predicted yield value (6.54%). The crude Fructus Jujubae polysaccharide was further purified by DEAE-cellulose chromatography repeatedly, and two homogenous fractions, designated as RQP1d and RQP2d with molecular weight of 83.8 and 123.0 kDa respectively, were obtained. Their structures were determined by chemical analysis, Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). Finally, preliminary immunological tests indicated that both RQP1d and RQP2d significantly stimulated NO production in RAW264.7 macrophages, and promoted LPS-induced splenocyte proliferation. These data implied Fructus Jujubae polysaccharides had the potential to be explored as novel natural immunostimulant for using in functional foods or medicine.

Chitosan coupling makes microbial biofilms susceptible to antibiotics.

Microbial biofilms, prevalent in nature and inherently resistant to both antimicrobial agents and host defenses, can cause serious problems in the chemical, medical and pharmaceutical industries. Herein we demonstrated that conjugation of an aminoglycoside antibiotic (streptomycin) to chitosan could efficiently damage established biofilms and inhibit biofilm formation. This method was suitable to eradiate biofilms formed by Gram-positive organisms, and it appeared that antibiotic contents, molecular size and positive charges of the conjugate were the key to retain this anti-biofilm activity. Mechanistic insight demonstrated chitosan conjugation rendered streptomycin more accessible into biofilms, thereby available to interact with biofilm bacteria. Thus, this work represent an innovative strategy that antibiotic covalently linked to carbohydrate carriers can overcome antibiotic resistance of microbial biofilms, and might provide a comprehensive solution to combat biofilms in industrial and medical settings.

Variation in antioxidant activities of polysaccharides from Fructus Jujubae in South Xinjiang area.

The Fructus Jujubae has been widely used as favorable food and folk medicine in China and Russia. In this study, we compared the carbohydrate constituents and antioxidative effects of Fructus Jujubae polysaccharides from five different production areas in South Xinjiang. Results demonstrated that the average annual temperature (r=0.590) and frost-free period (r=0.779) were well correlated to the uronic acid content, while the neutral carbohydrate content showed negative correlation with precipitation amount (r=-0.567). Antioxidative tests indicated that Fructus Jujubae polysaccharides could scavenge chemicals-induced reactive oxygen species in a dose-dependent manner. In addition, these polysaccharides could rescue H2O2-induced HUVEC death. The antioxidative activity of polysaccharides from the Fructus Jujubae might contribute to their diverse medicinal and nutritional values.

A decrease in moisture absorption-retention capacity of N-deacetylation of hyaluronic acid.

The linear non-sulfated glycosaminoglycan, hyaluronic acid (HA), is widely distributed throughout connective, epithelial and neural tissues etc., and is of great importance in tissue hydration, lubrication and cellular function. Along with the age growth, HA will lose its acetyl groups under action of HA N-deacetylase in vivo. However, the biological consequence of this physiological process remains largely unknown. Herein two highly N-deacetylated HAs, dHA-6 and dHA-10 were generated via the NH2NH2-HIO3 procedure. Their molecular weights were estimated to be 24 and 16 kDa by high performance gel-permeation chromatography (HPGPC), and the N-deacetylation degrees were 79.4 % and 93 % respectively, as determined by (1)H nuclear magnetic resonance (NMR). The study on moisture-absorption (Ra) and -retention (Rh) abilities demonstrated that the Ra values of dHAs under conditions of 81 % or 43 % relative humidity, as well as the Rh values of dHAs under dry condition or 43 % relative humidity, were significantly smaller than that of their respective re-N-acetylated products. The decline of moisture-absorption and -retention capacity after HA N-deacetylation were consistent with the appearance of unsolvated amides remained in the N-deacetylated products, as indicated by circular dichroism (CD) spectroscopy. Our findings implied that HA N-deacetylation, in addition to the decrease of HA contents in the elderly persons, might account for manifestations of naturally aged skin, such as laxity, sagging, and wrinkling.

Antioxidative properties of crude polysaccharides from Inonotus obliquus.

The mushroom Inonotus obliquus has been widely used as a folk medicine in Russia, Poland and most of the Baltic countries. In this study, water-soluble and alkali-soluble crude polysaccharides (IOW and IOA) were isolated from I. obliquus, and the carbohydrate-rich fractions IOW-1 and IOA-1 were obtained respectively after deproteination and depigmentation. Their contents, such as neutral carbohydrate, uronic acid and protein, were measured. Their antioxidant properties against chemicals-induced reactive species (ROS) including 1,1'-Diphenyl-2-picrylhydrazyl (DPPH) radical, hydroxyl radical and superoxide anion radical, as well as their protective effects on H(2)O(2)-induced PC12 cell death were investigated. Results showed that I. obliquus polysaccharides can scavenge all ROS tested above in a dose-dependent manner. IOA and its product IOA-1 could rescue PC12 cell viability from 38.6% to 79.8% and 83.0% at a concentration of 20µg/mL. Similarly, IOW and its product IOW-1 at the same dose, can also increase cell viability to 84.9% and 88.6% respectively. The antioxidative activities of water-soluble and alkali-soluble polysaccharide constituents from I. obliquus might contribute to diverse medicinal and nutritional values of this mushroom.