Seaweed polysaccharide fibers:Solution properties,processing and applications

Seaweed polysaccharides with abundantly renewable sources and charming properties have attracted arising attention.Alginate,carrageenan and agar with the largest are the most predominant species of common seaweed polysaccharides.This review will first provide a comprehensive overview of general information on seaweed polysaccharides regarding solubility,multilevel structure,viscoelasticity,and gelation.Then we summarize preparation methods of seaweed polysaccharides fibers including wet-spinning technique,electrospinning technique and microfluidic spinning.The applications of seaweed polysaccha-rides fibers,based on many excellent inherent properties,including biocompatibility,suitable microstruc-ture,nontoxicity,potential bioactivity,good intrinsic flame retardancy and thermal stability,are described in detail.

Effects of Enteromorpha prolifera polysaccharides on growth performance,intestinal barrier function and cecal microbiota in yellow-feathered broilers under heat stress

Background Global warming leading to heat stress(HS)is becoming a major challenge for broiler production.This study aimed to explore the protective effects of seaweed(Enteromorpha prolifera)polysaccharides(EPS)on the intestinal barrier function,microbial ecology,and performance of broilers under HS.A total of 144 yellow-feathered broilers(male,56 days old)with 682.59±7.38 g were randomly assigned to 3 groups:1)TN(thermal neutral zone,23.6±1.8℃),2)HS(heat stress,33.2±1.5℃ for 10 h/d),and 3)HSE(HS+0.1%EPS).Each group contained 6 replicates with 8 broilers per replicate.The study was conducted for 4 weeks;feed intake and body weights were measured at the end of weeks 2 and 4.At the end of the feeding trial,small intestine samples were collected for histomorphology,antioxidant,secretory immunoglobulin A(s Ig A)content,apoptosis,gene and protein expression analysis;cecal contents were also collected for microbiota analysis based on 16S r DNA sequencing.Results Dietary EPS promoted the average daily gain(ADG)of broilers during 3–4 weeks of HS(P<0.05).At the end of HS on broilers,the activity of total superoxide dismutase(T-SOD),glutathione S-transferase(GST),and the content of s Ig A in jejunum were improved by EPS supplementation(P<0.05).Besides,dietary EPS reduced the epithelial cell apoptosis of jejunum and ileum in heat-stressed broilers(P<0.05).Addition of EPS in HS group broilers'diet upregulated the relative m RNA expression of Occludin,ZO-1,γ-GCLc and IL-10 of the jejunum(P<0.05),whereas downregulated the relative m RNA expression of NF-κB p65,TNF-αand IL-1βof the jejunum(P<0.05).Dietary EPS increased the protein expression of Occludin and ZO-1,whereas it reduced the protein expression of NF-κB p65 and MLCK(P<0.01)and tended to decrease the protein expression of TNF-α(P=0.094)in heat-stressed broilers.Furthermore,the proportions of Bacteroides and Oscillospira among the three groups were positively associated with jejunal apoptosis and pro-inflammatory cytokine expression(P<0.05)and negatively correlated with jejunal Occludin level(P<0.05).However,the proportions of Lactobacillus,Barnesiella,Subdoligranulum,Megasphaera,Collinsella,and Blautia among the three groups were positively related to ADG(P<0.05).Conclusions EPS can be used as a feed additive in yellow-feathered broilers.It effectively improves growth performance and alleviates HS-induced intestinal injury by relieving inflammatory damage and improving the tight junction proteins expression.These beneficial effects may be related to inhibiting NF-κB/MLCK signaling pathway activation and regulation of cecal microbiota.

Extraction and Antioxidant Functions of Polysaccharides from Seaweed

Dried seaweed powder was used as the raw material to extract polysaccharides by ethanol precipitation after water bath. Extraction temperature, extrac- tion duration, solution pH and solid to liquid ratio were selected as technical parameters which required to be optimized. With the extraction rate of seaweed poly- saccharides as an index, single-factor experiment and orthogonal experiment were carried out to determine the optimal extraction technique. Seaweed polysaceharides were extracted with the optimal technical parameters to analyze the biological activities. Savage method was used to process seaweed polysaceharide extract. In vitro biological activities of preliminarily purified seaweed polysaeeharides were investigated successively, including reducing ability, antioxidant ability and antibacterial activity. The results showed that there was a positive correlation between polysaccharide concentration and its reducing ability, antioxidant ability and antibacterial activity. Furthermore, there was also a correlation among the reducing ability, antioxidant ability and antibacterial activity of seaweed polysaecharides; the relation- ship between each two of these three indicators was similar to positive linear correlation.

Molecular mechanisms of anti-cancer bioactivities of seaweed polysaccharides

Seaweed is a traditional Chinese medicine homologous to food,in which polysaccharides are responsible for anti-cancer by enhancing immunity,inducing cancer cell apoptosis,inhibiting cancer cell invasion and metastasis or directly scavenging oxidative free radicals that induce cancer cell changes.Among them,regulating immunity and promoting cancer cell apoptosis are intensively studied due to the important role in preventing cancer.Here we reviewed seaweed in the apoptosis-inducing signaling pathways including PI3K/AKT,ROS and JNK and discussed challenges in studying seaweed.