Chitin oligosaccharides alleviate atherosclerosis progress in ApoE;mice by regulating lipid metabolism and inhibiting inflammation

Atherosclerosis is driven both by hyperlipidemia and inflammation. Chitin oligosaccharides(NACOS) have shown pharmacological effects on multiple diseases via hypolipidemic and/or anti-inflammatory activities. The present study aims to evaluate whether NACOS treatment can prevent atherosclerosis induced by a highfat-diet(HFD) in Apolipoprotein E-knockout(Apo E;) mice. Results showed that 300 and 900 mg/kg b.w./day NACOS supplementation for 14 weeks significantly decreased atherosclerotic lesions up to 45% and 67% in compared with the HFD(P < 0.05), as measured in the valve area of the aortic root. Further, NACOS supplementation significantly reduced the serum hyperlipidemia and circulating proinflammatory cytokines including interleukin-1β, interleukin-6, monocyte chemoattractant protein-1 and tumor necrosis factor-α. NACOS decreased the hepatic Hmgcr to reduce cholesterol synthesis, activated the genes involved in reverse cholesterol transport to enhance cholesterol efflux and excretion, and reduced the intestinal Npc1L1 to lower cholesterol absorption. Additionally, NACOS enhanced cecum short chain fatty acids production and intestinal integrity. Thus, NACOS supplementation ameliorated atherosclerosis via altering lipid metabolism and reducing inflammation. These findings indicate that NACOS may be a potential functional food material for attenuating atherosclerosis development.

Chitin oligosaccharides for the food industry:production and applications

Chitin oligosaccharides(CHOS),high-value-added oligomers linked by N-acetyl-d-glucosamine(GlcNAc,NAG),and a small amount of d-glucosamine(GlcN,GA),have aroused increasing interest due to their excellent biological properties,including antibacterial,anti-inflammatory,and immunoprotective activities,and intestinal regulation.The efficient production and utilization of CHOS with high performance can solve problems from chitin as biowaste.However,the large-scale production of well-defined CHOS has not been fully accomplished due to the limited biotechnology and separation methods,thus impeding the research on their biological functions as well as their accurate applications.In this review,we comprehensively summarize the current preparation methods of CHOS,including the chemical,physical,enzymatic and biosynthetic methods.The advantages and disadvantages of the methods are discussed in terms of efficiency,economy,and environmental effects.Furthermore,the applications of CHOS in the food industry and their contributions to human health based on their excellent bioactivities are expounded.It is hoped that this review will help in providing new insights into the production of CHOS with high precision,and support the application of CHOS in serving the food industry as nutritional supplements or foods for special medical purposes.

Combinatorial metabolic engineering of Escherichia coli for de novo production of structurally defined and homogeneous Amino oligosaccharides

Amino oligosaccharides(AOs)possess various biological activities and are valuable in the pharmaceutical,food industries,and agriculture.However,the industrial manufacturing of AOs has not been realized yet,despite reports on physical,chemical,and biological approaches.In this study,the de novo production of chitin oligosaccharides(CHOS),a type of structurally defined AOs,was achieved in Escherichia coli through combinatorial pathway engineering.The most suitable glycosyltransferase for CHOS production was found to be NodCL from Mesorhizobium Loti.Then,by knocking out the nagB gene to block the flow of N-acetyl-d-glucosamine(NAG)to the glycolytic pathway in E.coli and adjusting the copy number of NodCL-coding gene,the CHOS yield was increased by 6.56 times.Subsequently,by introducing of UDP-N-acetylglucosamine(UDP-GlcNAc)salvage pathway for and optimizing fermentation conditions,the yield of CHOS reached 207.1 and 468.6 mg/L in shake-flask cultivation and a 5-L fed-batch bioreactor,respectively.Meanwhile,the concentration of UDP-GlcNAc was 91.0 mg/L,the highest level reported in E.coli so far.This study demonstrated,for the first time,the production of CHOS with distinct structures in plasmid-free E.coli,laying the groundwork for the biosynthesis of CHOS and providing a starting point for further engineering and commercial production.