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Journal: International journal of biological macromolecules


The global health emergency generated by coronavirus disease 2019 (COVID-19) has prompted the search for preventive and therapeutic treatments for its pathogen, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). There are many potential targets for drug discovery and development to tackle this disease. One of these targets is the main protease, Mpro or 3CLpro, which is highly conserved among coronaviruses. 3CLpro is an essential player in the viral replication cycle, processing the large viral polyproteins and rendering the individual proteins functional. We report a biophysical characterization of the structural stability and the catalytic activity of 3CLpro from SARS-CoV-2, from which a suitable experimental in vitro molecular screening procedure has been designed. By screening of a small chemical library consisting of about 150 compounds, the natural product quercetin was identified as reasonably potent inhibitor of SARS-CoV-2 3CLpro (Ki ~ 7 μM). Quercetin could be shown to interact with 3CLpro using biophysical techniques and bind to the active site in molecular simulations. Quercetin, with well-known pharmacokinetic and ADMET properties, can be considered as a good candidate for further optimization and development, or repositioned for COVID-19 therapeutic treatment.


In this study, we prepared seven polysaccharides extracted from five algae including one brown alga Saccharina japonica, one red alga Porphyra haitanensis and three green algae Codium fragile, Enteromorpha linza and Bryopsis plumose. The chemical composition and capability of moisture-absorption and moisture-retention were investigated in comparison with those of hyaluronic acid (HA). The low molecular weight polysaccharides extracted from brown seaweed exhibited the highest moisture-absorption and moisture-retention abilities of all of the polysaccharides studied and performed better than HA. The relationships between chemical composition (including sulfated groups, monosaccharide, and molecular weight) and the functions of polysaccharides were also studied. We found the sulfated group was a main active site for moisture-absorption and moisture-retention abilities. These abilities were also related to molecular weight; with the exception of the low molecular weight polysaccharide extracted from red seaweed, lower molecular weight improved moisture-absorption and moisture-retention abilities.

Concepts: Plant, Nori, Water, Green algae, Brown algae, Red algae, Seaweed, Algae


Pear-derived Weissella sp. TN610 produced extracellular glycosyltransferase activity responsible for the synthesis of soluble exopolysaccharide from sucrose. Acid and dextranase-catalyzed hydrolysis revealed that the synthesized polymer was a glucan. According to (1)H and (13)C NMR analysis, the glucan produced by TN610 was a linear dextran made of 96% α-(1→6) and 4% α-(1→3) linkages. Zymogram analysis confirmed the presence of a unique glucansucrase of approximately 180kDa in the cell-free supernatant from TN610. The crude enzyme, optimally active at 37°C and pH 5, has promising potential for application as a food additive since it catalyzes dextran synthesis in sucrose-supplemented milk, allowing its solidification. A 4257-bp product corresponding to the mature glucansucrase gene was amplified by PCR from TN610. It encoded a polypeptide of 1418 residues having a calculated molecular mass of 156.089kDa and exhibiting 96% and 95% identity with glucansucrases from Lactobacillus fermentum Kg3 and Weissella cibaria CMU, respectively.

Concepts: Food additives, Antioxidant, Lactobacillus fermentum, Molecular biology, Vinegar, Protein, Enzyme, Food additive


In the current work, chitosan extracted from waste shrimp shells was used in finishing formulation for cotton fabric, along with DMDHEU and other chemicals, imparting multiple performance characteristics such as wrinkle free, antibacterial and flame retardant properties. The finished fabrics were evaluated for textile properties like tensile strength, bending length, yellowness index and functional properties like crease recovery angle, antibacterial activity and flame retardancy and also for the ecological properties like formaldehyde release. The finished fabric showed excellent crease recovery, antibacterial property and flame retardancy which were retained to a moderate extent even after 20 washes. Besides formaldehyde scavenging action, chitosan clearly showed its positive role in imparting multifunctional properties to cotton.

Concepts: Aramid, Tent, Fire retardant, Yarn, Tensile strength, Flame retardant, Cotton, Textile


Chitosan (CS) nanofibers with a diameter of 150-200nm were fabricated from a mixed chitosan/poly (vinyl alcohol) (PVA) solution by the electrospinning method. The nascent CS/PVA nanofibers were treated with 0.5M NaOH solution to make stable CS nanofibers by removing PVA under aqueous conditions. Hen egg-white lysozyme was immobilized on electrospun CS nanofibers via cross-linked enzyme aggregates (CLEAs) and used for effective and continuous antibacterial applications. The maximum amount of lysozyme immobilized on the CS nanofibers was determined to be 62.3mg/g of nanofibers under the optimum conditions. The immobilized lysozyme-CLEA retained more than 75.4% of its initial activity after 80 days of storage at room temperature, while the free lysozyme lost all of its activity under the same conditions. In addition, the immobilized lysozyme-CLEA retained more than 76% of its activity after 100 consecutive uses. Finally, the durability of the lysozyme-CLEA immobilized CS nanofibers showed bacteriostasis ratios of 82.4%, 79.8%, 83.4%, and 84.1% after 10 cycles against 4 pathogenic bacteria, viz. Staphylococcus aureus, Bacillus subtilis, Shigella flexneri, and Psedomonas aeruginosa, respectively. These results demonstrated that lysozyme-CLEA immobilized CS nanofibers could be used as a promising material for enhanced and continuous antibacterial applications.

Concepts: Firmicutes, Shigella flexneri, Staphylococcus aureus, Bacillus subtilis, Immobilized enzyme, Bacillus, Microbiology, Bacteria


The roots of Sanguisorba officinalis are used in traditional Chinese medicine for the treatment of diseases such as inflammation and internal haemorrhage. Several scientific investigations involving extraction and pharmacological studies of terpenoids and triterpenoid glycosides from this herb have been carried out. However, little is known regarding the immunomodulatory and antioxidant properties of polysaccharides from S. officinalis. Hence the polysaccharides from this herb have been investigated here. The hot water extract of S. officinalis has been fractionated using size-exclusion chromatography to obtain four polysaccharide fractions designated as SOP-1, SOP-2, SOP-3 and SOP-4. The range of molecular masses of these fractions were from 280Da to 2000kDa, and their sugar compositions consisted mainly of fructose, glucose, xylose, arabinose, and rhamnose. The antioxidant activities of the crude polysaccharide fractions were evaluated in a biological assay using Saccharomyces cerevisiae, whereas the radical scavenging activity was measured using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Analysis of the immunomodulatory activities of these polysaccharide fractions were measured by using mouse macrophages. Most of the polysaccharide fractions have stimulated the production of nitric oxide and tumour necrosis factor-α (TNF-α), and also displayed antioxidant activities. These results suggest that the roots of S. officinalis are likely to have therapeutic value for the treatment of cancer.

Concepts: Xylose, Saccharomyces pastorianus, Glycosidic bond, Fungus, Saccharomyces cerevisiae, Polysaccharide, Monosaccharide, Glucose


Bio-based nanocomposite films were successfully developed using nanofibrillated cellulose (NFC) as the reinforcing phase and kappa-carrageenan (KCRG) as the matrix. NFC was successfully synthesis from short stable cotton fibers by chemo-mechanical process. The bionanocomposites were prepared by incorporating 0.1, 0.2, 0.3, 0.4, 0.5, and 1wt% of the NFC into a KCRG matrix using a solution casting method there characterization was done in terms of thermal properties (DSC), morphology (SEM), water vapor transmission rate (WVTR), oxygen transmission rate (OTR), X-ray diffractograms (XRD), and tensile properties. The main conclusion arising from the analysis of the result is that the bionanocomposites containing 0.4wt% of NFC exhibited the highest enhancement in tensile strength it is almost 44% improvement. WVTR and OTR results showed improvement of all nanocomposite film compare to control KCRG film.

Concepts: Water vapor, Cellulose, Materials science, Cellulose fiber, Water, Moisture vapor transmission rate, Cotton, Tensile strength


The chemical composition of shaddock (Citrus paradisi) mainly consisted of polyphenols, proteins and polysaccharides. However, polysaccharides from shaddock materials have received much less consideration than polyphenols. Herein, a water-soluble neutral polysaccharide from the endodermis of shaddock was isolated and showed good bioactivities. Crude polysaccharides from the endodermis of shaddock (EPS) was extracted with hot water and separated on a DEAE Sepharose FF gel filtration column to obtain NEPS. The IR and UV spectra of NEPS showed that NEPS was mainly composed of polysaccharide and there are no proteins existing in NEPS. The DPPH radical scavenging and reducing power of NEPS are much lower than those of crude EPS; however, Citrus flavonoids significantly improved the DPPH radical scavenging potential and reducing power of NEPS. The crude EPS (5mg/mL) showed a similar inhibitory effect (77.92±5.03%) with NEPS (5mg/mL) (74.63±4.71%) on α-amylase.

Concepts: Vitamin C, Polymer, Nitrogen, Pomelo, Citrus, Protein, Flavonoid, Polysaccharide


In order to develop a promising substitute for heparin, N-succinyl chitosan (NSC) was chemically modified by sulfating agent N(SO(3)Na)(3), which were synthesized with sodium bisulfite and sodium nitrite in aqueous solution. The N-succinyl chitosan sulfates (NSCS) products were characterized by infrared spectroscopy (FT-IR) and (13)C NMR. The degree of substitution (DS) of NSCS depended on the ratio of sulfating agent to N-succinyl chitosan, reaction temperature, reaction time and pH of sulfation agent. N-succinyl chitosan sulfates with DS of 1.97 were obtained under optimal conditions. The in vitro coagulation assay of NSCS was determined by activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) assays. The results showed that NSCS obviously prolonged APTT. The anticoagulant activity strongly depended on DS, molecular weight (M(w)) and concentration of NSCS. The anticoagulant activity of NSCS promoted with the increase of DS and concentration, and NSCS exhibited the best anticoagulant activity with the M(w) of 1.37×10(4).

Concepts: Spectroscopy, Factor XII, Heparin, Concentration, Partial thromboplastin time, Warfarin, Chemistry, Prothrombin time


The optimal conditions for sulfation of polysaccharides from persimmon fruits (PFP) with chlorosulfonic acid-pyridine (CSA-Pyr) method were determined by response surface methodology. Box-Behnken design was applied to evaluate the effects of three independent variables (volume ratio of Pyr to CSA, volume ratio of PFP to SO(3)Pyr and reaction time) on the degree of substitution (DS), molecular weight (MW) and activated partial thromboplastin time (APTT) of sulfated polysaccharides (PFP-S). The APTT activity of PFP-S could be improved by application of various volume ratio of Pyr to CSA, volume ratio of PFP to SO(3)Pyr and reaction time, which was possible due to the degradation of polysaccharides to different extent and increasing of DS. The optimal conditions to obtain the strongest APTT of PFP-S were the volume ratio of CSA to Pyr of 1:8, the volume ratio of SO(3)Pyr to PFP of 1:3.6 and the reaction time of 3h, respectively.

Concepts: Partial thromboplastin time, Persimmon