NaCl胁迫下外源壳聚糖对菜用大豆光合作用及叶绿体活性氧代谢的影响

采用蛭石栽培,以菜用大豆为试材,研究外源壳聚糖对NaCl胁迫下幼苗叶片光合作用及叶绿体活性氧(ROS)代谢的影响,以期探明NaCl胁迫下壳聚糖调控菜用大豆光合作用的生理机制。结果显示:NaCl胁迫下,外源壳聚糖通过诱导非气孔因素显著缓解了菜用大豆在胁迫中期(第6~12天)净光合速率(Pn)的下降;外源壳聚糖显著抑制了叶绿体O-·2的产生速率及H2O2含量的上升,显著提高了超氧化物歧化酶(SOD)、过氧化物酶(POD)、谷胱甘肽还原酶(GR)活性及抗坏血酸过氧化物酶(APX)在胁迫中期(第6~12天)的活性。无盐条件下,外源壳聚糖在处理早期对上述各指标产生了显著影响,中、后期该作用消失。上述结果表明:外源壳聚糖在NaCl胁迫下对菜用大豆的作用与无盐条件下不同;NaCl胁迫下,壳聚糖可诱导菜用大豆叶绿体保护酶活性及As A-GSH循环的运转速率,及时清除过量ROS,以抑制盐胁迫对光合膜的伤害,这可能是壳聚糖缓解Pn下降,进而缓解菜用大豆干质量下降的重要原因之一;外源壳聚糖的作用具有时效性。     

明胶-壳聚糖可食膜的制备及性能表征

以明胶和壳聚糖为成膜材料,以水蒸气透过率、抗拉强度和断裂伸长率为考察指标,研究可食膜制备的最佳工艺条件,同时采用红外光谱、X-射线衍射、扫描电镜和热稳定性分析对可食膜进行了性能表征研究。结果表明,最佳成膜工艺条件为:明胶与壳聚糖共混比例4∶6,明胶浓度1.5%,甘油浓度0.3%,吐温-80浓度0.1%,该工艺条件下制得的可食性共混膜较单一成分的膜具有较低的水蒸气透过率,且抗拉强度和断裂伸长率较高。对复合膜的性能表征研究结果表明,明胶与壳聚糖之间相容性较好,相互作用强烈。     

Recent Modifications of Chitosan for Adsorption Applications: A Critical and Systematic Review

Chitosan is considered to be one of the most promising and applicable materials in adsorption applications. The existence of amino and hydroxyl groups in its molecules contributes to many possible adsorption interactions between chitosan and pollutants (dyes, metals, ions, phenols, pharmaceuticals/drugs, pesticides, herbicides, etc.). These functional groups can help in establishing positions for modification. Based on the learning from previously published works in literature, researchers have achieved a modification of chitosan with a number of different functional groups. This work summarizes the published works of the last three years (2012–2014) regarding the modification reactions of chitosans (grafting, cross-linking, etc.) and their application to adsorption of different environmental pollutants (in liquid-phase).     

Chitosanases from Family 46 of Glycoside Hydrolases: From Proteins to Phenotypes

Chitosanases, enzymes that catalyze the endo-hydrolysis of glycolytic links in chitosan, are the subject of numerous studies as biotechnological tools to generate low molecular weight chitosan (LMWC) or chitosan oligosaccharides (CHOS) from native, high molecular weight chitosan. Glycoside hydrolases belonging to family GH46 are among the best-studied chitosanases, with four crystallography-derived structures available and more than forty enzymes studied at the biochemical level. They were also subjected to numerous site-directed mutagenesis studies, unraveling the molecular mechanisms of hydrolysis. This review is focused on the taxonomic distribution of GH46 proteins, their multi-modular character, the structure-function relationships and their biological functions in the host organisms.     

The Potential of Chitosan and Its Derivatives in Prevention and Treatment of Age-Related Diseases

Age-related, diet-related and protein conformational diseases, such as atherosclerosis, diabetes mellitus, cancer, hypercholesterolemia, cardiovascular and neurodegenerative diseases are common in the elderly population. The potential of chitosan, chitooligosaccharides and their derivatives in prevention and treatment of age-related dysfunctions is reviewed and discussed in this paper. The influence of oxidative stress, low density lipoprotein oxidation, increase of tissue stiffness, protein conformational changes, aging-associated chronic inflammation and their pathobiological significance have been considered. The chitosan-based functional food also has been reviewed.     

Long-Term Feeding of Chitosan Ameliorates Glucose and Lipid Metabolism in a High-Fructose-Diet-Impaired Rat Model of Glucose Tolerance

This study was designed to investigate the effects of long-term feeding of chitosan on plasma glucose and lipids in rats fed a high-fructose (HF) diet (63.1%). Male Sprague-Dawley rats aged seven weeks were used as experimental animals. Rats were divided into three groups: (1) normal group (normal); (2) HF group; (3) chitosan + HF group (HF + C). The rats were fed the experimental diets and drinking water ad libitum for 21 weeks. The results showed that chitosan (average molecular weight was about 3.8 × 10⁵ Dalton and degree of deacetylation was about 89.8%) significantly decreased body weight, paraepididymal fat mass, and retroperitoneal fat mass weight, but elevated the lipolysis rate in retroperitoneal fats of HF diet-fed rats. Supplementation of chitosan causes a decrease in plasma insulin, tumor necrosis factor (TNF)-α, Interleukin (IL)-6, and leptin, and an increase in plasma adiponectin. The HF diet increased hepatic lipids. However, intake of chitosan reduced the accumulation of hepatic lipids, including total cholesterol (TC) and triglyceride (TG) contents. In addition, chitosan elevated the excretion of fecal lipids in HF diet-fed rats. Furthermore, chitosan significantly decreased plasma TC, low-density lipoprotein cholesterol (LDL-C), very-low-density lipoprotein cholesterol (VLDL-C), the TC/high-density lipoprotein cholesterol (HDL-C) ratio, and increased the HDL-C/(LDL-C + VLDL-C) ratio, but elevated the plasma TG and free fatty acids concentrations in HF diet-fed rats. Plasma angiopoietin-like 4 (ANGPTL4) protein expression was not affected by the HF diet, but it was significantly increased in chitosan-supplemented, HF-diet-fed rats. The high-fructose diet induced an increase in plasma glucose and impaired glucose tolerance, but chitosan supplementation decreased plasma glucose and improved impairment of glucose tolerance and insulin tolerance. Taken together, these results indicate that supplementation with chitosan can improve the impairment of glucose and lipid metabolism in a HF-diet-fed rat model.     

壳聚糖对芒果离体叶片渗透胁迫的缓解效应

研究不同浓度壳聚糖溶液对芒果(Mangiferaindica)离体叶片在20%聚乙二醇(PEG-6000)渗透胁迫条件下生理生化的影响,结果表明,渗透胁迫下,壳聚糖可减缓叶片中水分的丧失以及叶绿素含量的下降,并能提高过氧化物酶活性和增加脯氨酸含量。因此,壳聚糖可有效缓解渗透胁迫对植物的损伤,提高植物的抗旱性。     

NaCl plus chitosan as a dietary salt to prevent the development of hypertension in spontaneously hypertensive rats

The effect of NaCl plus 3% chitosan on the systolic blood pressure of spontaneously hypertensive rats (SHR) were evaluated and compared with NaCl plus KCl (NaCl, 49.36% + KCl 49.36%) and chitosan or NaCl treatment alone. In SHR, administration of NaCl plus chitosan (44 mM Na/day) for two months significantly decreased the systolic blood pressure greater than of NaCl plus KCl and NaCl alone. NaCl plus chitosan resulted, though not statistically significant, in decreased urinary Na⁺ excretion and decreased blood urea nitrogen levels. Urinary creatinine of NaCl plus chitosan was slightly decreased compared to 3 treated groups. Serum electrolytes levels, however, remained unchanged. The combination of NaCl and chitosan may be superior to the conventional use of NaCl plus KCl or NaCl alone in the prevention of hypertension. Even though these supplementary diets have demonstrated potential anti-hypertensive effects in the experimental animal model, further research is needed before any recommendations can be made.     

壳聚糖对丰都红心柚保鲜效果的影响

采用H202氧化降解法制备相对分子质量(Mw)为1 500～2000的低分子质量壳聚糖.先用有益微生物制剂100液浸果2 min,再用浓度为1.5%的低分子质量壳聚糖涂膜保鲜丰都红心柚.试验结果表明,在常温和普通民房贮藏条件下贮藏100天,其烂果率为9.2%、干疤率为10.3%,防腐保鲜效果优于化学防腐保鲜剂.     

魔芋葡苷聚糖/壳聚糖共混胶黏剂应用于胶合板的研究

以胶合强度为考察指标,进行魔芋葡苷聚糖/壳聚糖共混配比胶黏剂工艺的制备研究.试验结果表明,胶黏剂中各组分用量的较佳参数为:壳聚糖1%,魔芋葡苷聚糖1.5%,NaOH为1%.此配比制备的胶黏剂压制的胶合板,干状胶合强度最大;在壳聚糖1%,魔芋葡苷聚糖1.5%,NaOH为2%的配比时,胶合板的湿状胶合强度最大.