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Algal Polysaccharides
Published in Gokare A. Ravishankar, Ranga Rao Ambati, Handbook of Algal Technologies and Phytochemicals, 2019
M Clemente-Carazo, V Sanchez, S Condon-Abanto, Garcia-Vaquero Marco
Microalgae are also a promising source of other valuable compounds such as polysaccharides. For instance, extra-cellular and sulphated polysaccharides extracted from Porphyridium, Chlorella and Spirulina sp. namely alguronic acid are used as cosmeceutical, nutraceutical and pharmaceutical (Borowitzka 2013, Laurienzo 2010, Raposo, de Morais and Bernardo de Morais 2013). Recently, microalgal polysaccharides have dragged the attention of the scientific community due to the wide range of biological properties of these compounds (see Tables 1.1 and 1.2). Several bioactivities from microalgal polysaccharides include antiviral, antibacterial, antioxidant, anti-inflammatory, immunomodulatory, antitumour, anti-lipidemic, anti-glycemic, anticoagulant, anti-thrombotic, bio-lubricant and anti-adhesive properties (de Jesus Raposo, de Morais and de Morais 2014a). Moreover, extra-cellular polysaccharides produced by cyanobacteria have also been used as soil conditioners, improving the water holding capacity of the soil and the detoxification of heavy metals/radionuclides and removal of solid matter from contaminated water (Bender and Phillips 2004). Some extra-cellular polysaccharides produced by marine microorganisms are currently in the cosmeceutical market with great success. For example, extra-cellular polysaccharides from Alteromonas macleodii (Abyssine®) and glycoproteins from Pseudoalteromonas sp. (SeaCode®) (Martins et al. 2014). However, the main producers of extra-cellular polysaccharides currently in the market are bacteria from the species Xanthomonas, Leuconostoc, Sphingomonas and Alcaligenes that produce xanthan, dextran, gellan and curdlan (Öner 2013).
Nanoparticle-Mediated Small RNA Deliveries for Molecular Therapies
Published in D. Sakthi Kumar, Aswathy Ravindran Girija, Bionanotechnology in Cancer, 2023
Ramasamy Paulmurugan, Uday Kumar Sukumar, Tarik F. Massoud
While many synthetic biodegradable polymers have been used to synthesize nanoparticles for drugs and nucleic acid deliveries, a number of polymers of natural sources (natural polymers) have also been successfully used for nanoparticle synthesis in drug delivery applications. Carbohydrates, proteins, and muscle fibers are some natural polymers used in nanoparticle synthesis. However, most of these natural polymer materials are derived from plants (starch, hemicellulose, cellulose, glucomannan, pectin, agar, etc.), microbes (curdlan, gellan, and xanthan), algae (alginate and carrageenan), and fungi (pullulan, chitin, and scleroglucon). The gelling property of many of these natural polymers has been explored for drug delivery, especially for the slow release of drugs. Originally natural polymers were used as adjuvants in vaccine deliveries. Natural polymers are widely used in small molecule drug deliveries, but their use in small RNA delivery is very limited. Predominantly, polysaccharide-based nanoparticles were used for siRNA deliveries in cancer therapy. Similarly, chitosan and hyaluronic acid are the other two natural polymers used for siRNA delivery [133]. Since chitosan is a positively charged polymer, it is commonly used to deliver negatively charged nucleic acids. The nanoparticles prepared from other neutral and negatively charged polymers need additional coating for loading of negatively charged nucleic acids or direct conjugation of nucleic acids using cleavable linkers before they can be used for deliveries. Chitosan is combined with other synthetic polymers as hybrid polymers for nucleic acid deliveries. Chitosan has also been used as a coating material to functionalize metal nanoparticles for nucleic acid deliveries. We recently showed that gold–iron oxide nanoparticles coated with chitosan–cyclodextrin hybrid polymer can be used for efficient intranasal delivery of miRNAs as a GBM therapy [37].
Metabolomics of Microbial Biofilms
Published in Chaminda Jayampath Seneviratne, Microbial Biofilms, 2017
Tanujaa Suriyanarayanan, Chaminda Jayampath Seneviratne, Wei Ling Ng, Shruti Pavagadhi, Sanjay Swarup
The analysis of EPS is quite challenging because of its complex nature and difficulty of extraction. Most of the common EPS extraction methodologies are suitable only for obtaining the soluble portion of the EPS. The insoluble portion of EPS is difficult to isolate, and very few methods are developed keeping this criterion in consideration [96]. The abundance of carbohydrate moieties in the EPS greatly complicates the extraction process. Most of these exopolysaccharides are insoluble and not easily separated from the cells, making the precise determination of their physical properties and chemical structures very difficult. Moreover, they can exist in either ordered or disordered forms [98]. The disordered forms are favoured by elevated temperatures and extremely low ionic concentrations. Based on the surrounding environment, biofilms can be exposed to a wide range of hydrodynamic conditions, which can greatly influence the matrix and structure of biofilms. The majority of the matrix exopolysaccharides are very long with linear or branched chains and a molecular mass of 500–2,000 kDa. They can be either homopolymers such as cellulose, curdlan or dextran, or heteropolymers such as alginate, emulsan, gellan or xanthan. They are generally constituted by monosaccharides and some non-carbohydrate substituents such as acetate, pyruvate, succinate and phosphate. The composition and conformation of the sugar monomers determine the properties of the exopolysaccharides and thus ultimately of the biofilm matrix. Mono-carbohydrate exopolysaccharides are often constituted by sugars such as d-glucose, d-galactose, d-mannose, l-fucose, l-rhamnose, l-arabinose, N-acetyl-d-glucose amine and N-acetyl-d-galactose amine as well as the uronic acids d-glucuronic acid, d-galacturonic acid, d-manuronic acid and l-guluronic acid. Some of the less frequently occurring sugar monomers are d-ribose, d-xylose, 3-keto-deoxy-d-mannooctulosonic acid and several hexoseamineuronic acids [96].
Host-directed antileishmanial interventions: Harvesting unripe fruits to reach fruition
Published in International Reviews of Immunology, 2023
Another category of PRRs are C-type lectin receptors (CLRs), but unlike TLRs, they are not always tasked with host defence. For instance, the C-type lectin receptor (CLR), DC-SIGN found on dendritic cells promotes uptake of L. mexicana promastigotes during in vitro infection [33], and its functional blocking is associated with reduced infection in moDCs. Other CLRs such as Dectin-1 have a pronounced macrophage-activating effect in response to L. infantum infection [34]. Stimulation with agonist, curdlan revealed enhanced CD4+ T cell proliferation and DC maturation [34]. That DC-SIGN holds potential as a target for immunomodulation was further validated in a study that reported how alteration in functions of DC-SIGN by polysaccharide moiety of AM3 hinders the capture and uptake of Candida, Leishmania, and Aspergillus parasites [35]. Recently, agonist to aryl hydrocarbon receptor (AhR), has also been associated with granuloma formation, leading to local induction of tumor necrosis factor (TNF) in macrophages and a weakened Th2 response [36].
Linear and branched β-Glucans degrading enzymes from versatile Bacteroides uniformis JCM 13288T and their roles in cooperation with gut bacteria
Published in Gut Microbes, 2020
Ravindra Pal Singh, Sivasubramanian Rajarammohan, Raksha Thakur, Mohsin Hassan
The β- glucans have gained strong attention as an imperative in food supplements, wherein they can act as either immunostimulants in cancer treatments and inflammation10,11 or microbiome modulatory agents.12 The β- glucans are predominantly present in the daily human diet in soluble and insoluble fiber states. These are structurally diverse with a variety of glycosidic linkages. For instance, β-glucans extracted from Euglena (known as paramylon) and bacterial polysaccharides (known as curdlan) are linear in chain with β-1-3 linked,13 while marine macroalgal-extracted glucan (known as laminarin) is branched with β-1-3 and β-1-6 linkages.14 Furthermore, frequency and length of β-1-6 linked glucans depend on the type of sources, i.e. yeast, Laminarin digitata, Lasallia pustulata, and Lentinus edodes.15–18 Curdlan is one of the abundant bio-resources that can be synthesized by several bacteria, including Agrobacterium,19Rhizobium,20 and Cellulomonas species.21,22 In addition, huge quantities of laminarin can accumulate in marine environment upon degradation of macroalgae, and plays a major role in marine carbon cycle.23,24 Therefore, extraction of curdlan and laminarin is much simpler as compared to other natural glycans and can be easily exploited for nutraceutical perspectives.25–27 However, laminarin and curdlan utilizing capability of gut bacteria is still poorly understood.