The Development of Improved Therapeutics through a Glycan- “Designer” Approach
Peter Grunwald in Pharmaceutical Biocatalysis, 2019
There are four known types of glycosylation based on the type of carbohydrate-peptide linkage: N-linked (Asparagine), O-linked (Threonine, Serine) C-linked (via Carbon atom) and S-glycosylation (Cysteine). Glycosylation can be further diversified on the base of glycosidic linkage, glycan composition, structure, and length. The N-type glycosylation in which glycan is attached to the amine group of asparagine residue resulting in formation of amide bond, is the most prevalent naturally occurring glycosylation type. The most common glycan linkage in human body among N-glycans is N-acetylglucosamine (GlcNAcβ1-Asn) found abundant in human serum. Overall different N-glycans are prevalent structures in prokaryotic surface proteins with a unique species-specific oligosaccharide structure; for that reason the glycoproteins derived from pathogens are excellent immunogens. The synthesis of N-glycans is well described for both prokaryotes and eukaryotes. While glycosylation in prokaryotes can be easily predicted and controlled the synthesis of all eukaryotic N-glycans is more complexed.
Role of Tumor Cell Membrane in Hyperthermia
Leopold J. Anghileri, Jacques Robert in Hyperthermia In Cancer Treatment, 2019
Glycoproteins and glycolipids are components in the plasma membrane of all mammalian cells. Glycoproteins usually contain multiple sugar chains with different structures. The identification of the carbohydrate moieties of a great number of glycoproteins and glycolipids has been accomplished during the last two decades.97,98 All sugar molecules in a glycoprotein are attached to the polypeptide backbone as side chains of oligosaccharides or polysaccharides that are formed by O-glycosidic bonds between carbon-1 (the anomeric carbon) of one monosaccharide and any of three or more ring carbons of another monosaccharide. Alpha- or beta-glycosidic linkages can be formed by the anomeric carbon; in each case the oxygen atom is below or above the plane of the sugar ring, respectively. The carbohydrate-peptide linkage takes place through the terminal reducing groups of these oligo- or polysaccharides (Figure 6). Pronase digestion of glycoproteins and analysis of the isolated glycopeptides has been the method used to isolate carbohydrate chains for structural analysis.99
Medicinal Mushrooms
Anil K. Sharma, Raj K. Keservani, Surya Prakash Gautam in Herbal Product Development, 2020
β-D-glucans are a naturally occurring structural constituent of the cell walls of mushrooms, mycelium, yeast, and certain bacteria. About 50% of the mass for the cell wall in a fungus is made up of β-glucans (Rop et al., 2009; Wasser, 2002; Wasser and Weis, 1999a). Research into the active polysaccharides in basidiomycetes has identified them as β-D-glucans (Rop et al., 2009; Vetvicka et al., 2008). β-glucans contain a glucose polymer-chain core which are held together by a linear linkage. The glycosidic linkage can present as (β-1 → 3), (β-1 → 4), (β-1 → 6), or a mixture of these (Volman et al., 2010a). However, the designation of the branching depends on the species of the mushroom (Rop et al., 2009). This is the reason why β-glucans from different sources have different structures. For instance, the structure for the β-glucans of mushrooms which have β-1 → 3 and β-1 → 6 side branches is different from those of bacteria that have β-1 → 4 side branches (Sakagami and Aoki, 1991).
Extraction and chemical characterization of novel water-soluble polysaccharides from two palm species and their antioxidant and antitumor activities
Published in Egyptian Journal of Basic and Applied Sciences, 2020
Dawood H. Dawood, Mohamed S. Elmongy, Amr Negm, Mohamed A. Taher
It could be divided the linkages in the structure of glycoproteins into two categories on the basis of their stability to alkali: O- glycosidic linkages and N-glycosidic linkages [53]. The alkali-sensitive O-glycosidic linkages (involving Xyl, GlcNAc, Gal or Man and Ser or Thr) were readily split in relatively mild conditions by a β-elimination mechanism resulting in the release of the carbohydrate moiety. This method has been widely employed to analyze the type of linkages in glycoproteins [51]. In this study, the distinct absorbance at 240 nm in the presence of alkali treatment exhibiting that the β-elimination reaction had taken place. Thus, the sugars were linked to the polypeptide backbone via an O-linkage in CM and CH polysaccharides, similar findings have been reported by Dawood et al. [44] and Tsai et al. [54].
Effect of rutin on pharmacokinetic modulation of diclofenac in rats
Published in Xenobiotica, 2020
Ashish Dogra, Abhishek Gour, Shipra Bhatt, Priyanka Sharma, Anjna Sharma, Pankul Kotwal, Priya Wazir, Prashant Mishra, Gurdarshan Singh, Utpal Nandi
Nowadays, the use of oral bioavailability enhancer (bioenhancer) has also gained significant importance. The use of bioenhancer for a drug is a pharmacological approach to occur positive pharmacokinetic interaction of a drug through intended drug interaction. Bioenhancer helps to reduce severe dose-related toxicity that can be beneficial to continue prolonged duration of drug therapy as well as can achieve better patient compliance. In other way, the use of bioenhancer can trim down the dose to offset dose-dependent side effects (Randhawa et al., 2011; Tatiraju et al., 2013). In this direction, rutin can also be a perfect choice as it is a glycoside of quercetin, which is reported to have the potential to elevate plasma concentrations of drugs (Randhawa et al., 2011). However, quercetin is also found to lessen the oral exposure of drugs (Vrolijk et al., 2015; Yu et al., 2011). Generally, the addition of glycosidic linkage to the aglycone part prominently affects the physicochemical properties and, consequently, its therapeutic efficacy. Hence, it would be useful to explore the role of rutin on the pharmacokinetic modulation and consequent efficacy of diclofenac.
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.
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