Strong Hydrogen-bonding Interactions Research Articles

Stabilizing MXene-based nanofiltration membrane by forming analogous semi-interpenetrating network architecture using flexible poly(acrylic acid) for effective wastewater treatment

Two-dimension MXene (Ti3C2Tx) membrane has attracted widespread interest in water treatment to relieve the problem of clean water shortage. Nevertheless, notorious swelling and subsequent instability problems of the MXene-based membrane when immersing in water hinder its wide application, owing to the weak interaction between the adjacent MXene laminates. Herein, a feasible strategy is proposed to stabilize and tune the nanochannels of MXene-based membranes and achieve superior nanofiltration efficiency. Poly(acrylic acid) (PAA) macromolecules are firstly inserted into the MXene nanosheets and form PAA-modified MXene (PAA-MXene) dispersion. Then, the dispersion is vacuum filtered on the electrospun polyacrylonitrile (PAN) nanofibrous substrate to form an ultra-thin PAA-MXene hydrogel barrier layer, thus assembling into PAA-MXene/PAN composite membrane. The MXene laminates will be intertwined by the long chain of flexible PAA macromolecules and thus form homologous semi-interpenetrating network structure with MXene as physical crosslinker through strong hydrogen-bond interaction, which will restrict the obvious structural change of MXene nanosheets and effectively adjust their d-spacing at ∼14.28 Å with MXene: PAA mass ratio of 1:0.5. The synergic effect of PAA and MXene nanosheets, as well as electrospun PAN nanofibrous substrate, endows the PAA-MXene/PAN membrane with superior nanofiltration performance to various dyes. The optimum PAA-MXene/PAN membrane possesses permeate fluxes of 271.26, 516.34, 300.83 L m−2 h−1 and rejections of 98.92%, 99.52%, 98.12% to DR80, AB8GX and AB90 at 0.1 MPa, respectively, which exhibit distinct advantage than the MXene-based membrane in literature. In addition, the PAA-MXene/PAN membrane has good long-time durability and is more suitable for low pressure nanofiltration. All these make PAA-MXene/PAN membrane a promising nanofiltration membrane for wastewater treatment.

Synthesis, spectral characterization, single crystal X-ray diffraction, and antimicrobial properties of 1-(4-iodo-1-hydroxynaphthalen-2-yl)ethan-1-one

This paper describe synthesis of 1-(4-iodo-1-hydroxynaphthalen-2-yl)ethan-1-one (3) from 2-acetyl-1-naphthol 2 by using I 2 /HIO 3 in ethanol under reflux condition. The structure of titled compound confirmed through spectral techniques. A well grown single crystal was developed using solvent evaporation technique for their X-ray diffraction analysis. The results showed that compound 3 crystallize in the monoclinic crystal system with Z value of four and space group symmetry P21/n. Whereas unit cell dimensions and angles are a; 7.5183 Å, b; 9.7529 Å, c; 14.8633 Å, α; 90°, β; 91.923°, γ; 90°. Moreover crystal data and packing view demonstrated that crystal was stabilized by one strong classical hydrogen bond interaction (O(2)-H(2)...O(1)) and two weak intermolecular hydrogen bonding. The synthesized compound was evaluated for antimicrobial activity against the Bacillus subtilis, Escherichia Coli, Pseudomonas Aeruginosa, Aspergillus flavus, Aspergillus Niger and Candida albicans organisms. Biological activity revealed that the compound 3 show significant to moderate activity. Single crystal packing view of 1-(4-iodo-1-hydroxynaphthalen-2-yl)ethan-1-one.

Energy frameworks and Hirshfeld surface analysis of supramolecular features in three new phosphoric triamides: tuning the intermolecular interactions via the substituent effect

Supramolecular features observed in the crystal structures of phosphoric triamides are mostly influenced by strong hydrogen bond interaction N—H...OP. With the aid of substituent groups a scenario can be created where the crucial role of weak interactions towards the stabilization of the overall molecular packing, in the absence of any strong interaction can be evaluated more reliably. In this context, we have studied the supramolecular features of three new phosphoric triamides 1 – 3, with [NH]P(O)[N]2, [C(O)N]2P(O)[N] and [C(O)N]2P(O)[NH] segments, respectively. The compounds crystallize in the monoclinic space groups P21/c for 1 and 2 with one phosphoric triamide molecule and in P21 for 3 with two molecules in the asymmetric unit. The intermolecular interactions and their energies are evaluated using Hirshfeld surface and energy framework analyses revealing that the presence or absence of substituent groups such as 2-oxo-3-oxazolidinyl may serve as a crucial cohesive factor in the supramolecular assembly. The substituent alters the intermolecular interaction contributions, with subsequent changes in the formation of different weak interactions and molecular assemblies. The structure of 2 bearing this substituent displays the highest energy interaction without any strong interaction. The crystal packing is stabilized by a variety of interactions involving the weak hydrogen bonds with the PO and CO acceptor sites. The effects of substituent groups on the molecular frameworks formed by various intermolecular interactions are analyzed in detail via energy framework diagrams. Finally, a biological study by the molecular docking method indicates that the studied here compounds could be appropriate candidates as SARS-CoV-2 inhibitors.

A versatile hydrogel network-repairing strategy achieved by the covalent-like hydrogen bond interaction.

Hydrogen bond engineering is widely exploited to impart stretchability, toughness, and self-healing capability to hydrogels. However, the enhancement effect of conventional hydrogen bonds is severely limited by their weak interaction strength. In nature, some organisms tolerate extreme conditions due to the strong hydrogen bond interactions induced by trehalose. Here, we report a trehalose network–repairing strategy achieved by the covalent-like hydrogen bonding interactions to improve the hydrogels’ mechanical properties while simultaneously enabling them to tolerate extreme environmental conditions and retain synthetic simplicity, which proves to be useful for various kinds of hydrogels. The mechanical properties of trehalose-modified hydrogels including strength, stretchability, and fracture toughness are substantially enhanced under a wide range of temperatures. After dehydration, the modified hydrogels maintain their hyperelasticity and functions, while the unmodified hydrogels collapse. This strategy provides a versatile methodology for synthesizing extremotolerant, highly stretchable, and tough hydrogels, which expand their potential applications to various conditions.

Computer Aided Drug Design Approach to Screen Phytoconstituents of Adhatoda vasica as Potential Inhibitors of SARS-CoV-2 Main Protease Enzyme.

A novel coronavirus (COVID-19) was identified as one of the severe acute respiratory syndrome coronaviruses (SARS-CoV-2) and emerged as a pandemic in 2020. Thus, there is an urgent need to screen and develop an agent to suppress the proliferation of viral particles of SARS-CoV-2, and several drugs have entered clinical trial phases to assess their therapeutic potential. The objective of the present study is to screen phytochemicals against the main viral protease using molecular docking studies. The phytochemicals vasicine, vasicinone, vasicinolone, vasicol, vasicolinone, adhatodine, adhavasicinone, aniflorine, anisotine, vasnetine, and orientin from Adhatoda vasica were selected, and the compounds were docked with various viral protein targets, including specific SARS-CoV-2 main protease (PDBID:6Y84), using AutoDock, Schrodinger, Biovia discovery studio, and virtual screening tools. Adhatodine and vasnetine showed a better binding affinity of −9.60 KJ/mol and −8.78 KJ/mol, respectively. In molecular docking simulations for 10 ns, these compounds illustrated strong hydrogen-bonding interactions with the protein active site and induced a potential conformational change in the ligand-binding site. The results were compared with the antiviral drugs nirmatrelvir and ritonavir. These results suggest that these phytochemicals can be studied as potential inhibitors against SARS-CoV-2 protease and may have an antiviral effect on coronavirus. However, further in vitro and in vivo efficacy activity needs to be investigated for these phytochemicals.

Effects of aramid nanofibers on the mechanical properties of epoxy resin and improved adhesion with aramid fiber

AbstractInspired by the application of nano‐fillers in composite materials, well‐dispersed aramid nanofibers (ANFs) were prepared and added into the epoxy resin (EP) to improve the toughness and tenacity properties of the ANF/EP composites. The composites were characterized by mechanical property test, surface analysis, thermodynamic property analysis, and contact angle. Results showed that when the EP was added with 0.15 wt% ANF, the tensile strength, bending strength, and impact strength are increased by 28.2%, 81.9%, and 81.8% compared with pure EP, respectively. The thermal stability and infiltration of the composites are improved. The interlaminar shear strength and interfacial shear strength of the aramid fiber were increased by 53.1% and 92.7% compared with the not reinforced EP, demonstrating that the epoxy reinforced with ANF is also beneficial for improving the interfacial bonding strength of aramid fiber and EP. The mechanism of the epoxy reinforcement by ANF and the interface enhancements showed that the ANF could cause several crack bridges and strong hydrogen bond interaction interface.

An anti-freezing and anti-drying multifunctional gel electrolyte for flexible aqueous zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) have attracted immense attention for flexible energy storage devices due to their high safety and low cost. However, conventional flexible aqueous ZIBs will undergo severe capacity loss at subzero temperature due to the inevitably freeze of electrolytes. In addition, under large bending or stretching strains, the encapsulation of devices would be damaged, which causes the evaporation of water in electrolytes and results in device failure. Herein, an anti-freezing and anti-drying gel electrolyte based on polyacrylamide (PAM) and glycerol (Gly) is developed. The strong hydrogen-bonding interactions between PAM or Gly and water molecules not only avoid the crystallization of the gel electrolyte at low temperatures, but also constrain the free water and restrict its evaporation. Therefore, such gel electrolyte displays a high ionic conductivity of 9.65 × 10−5 S cm−1 at −40°C. Furthermore, it can restrict the dehydration process when the electrolyte is exposed to ambient environment. The flexible ZIBs based on such gel electrolyte exhibit excellent electrochemical performance at −40°C and the devices without encapsulation retain 98% of their initial capacity in ambient condition after 30 days. This work provides a route to design anti-freezing and anti-drying gel electrolytes for aqueous energy storage devices.

Design and evaluation of sodium alginate/polyvinyl alcohol blend hydrogel for 3D bioprinting cartilage scaffold: molecular dynamics simulation and experimental method

To determine the optimum composition of AS/PVA for bioprinting cartilage scaffold, a molecular simulation combining experimental method was employed to investigate the microstructure, physicochemical properties and printability of AS/PVA blending hydrogels at different compositions. The compatibility analysis results show that SA and PVA have a good compatibility, they are miscible at any compositions. Mechanical properties analysis indicates that the tensile strength of 8SA/2PVA is the best, and compared with 8SA/2PVA, 7SA/3PVA possesses a better toughness and similar tensile strength. Moreover, FFV value and pore size decrease with the increase of PVA content, indicating the incorporation of PVA makes the system denser and pore size smaller, and the hydrogel of 8SA/2PVA possesses the optimal pore structure for the proliferation of chondrocytes. The main reason behind the conclusions obtained above is attributed to the strong hydrogen bond and intermolecular interaction between SA and PVA molecular chains. Finally, the results of printability indicates that, due to the fluidity of PVA, the forming quality becomes worse with the increase of PVA content, and when the PVA content in hydrogel precursors is within 30 wt.%, the forming quality is relatively good. Comprehensive considering the results above, the blend hydrogel of 8SA/2PVA was selected out and considered to be the most suitable for 3D printing cartilage scaffolds.

Co-modification of corn straw lignin and its enhancement on glue-free fiberboard based on freezing activated wood fibers

Glue-free fiberboard, as a substitute for traditional fiberboard, does not contain a large amount of synthetic resins, which can avoid harm to human health and environment. However, glue-free fiberboard still has some disadvantages of insufficient mechanical strength and excessive thickness swelling of water absorption. Here, corn straw lignin was co-modified by demethylation/hydrothermal degradation to obtain high hydroxyl content increased by 210.85% compared with raw lignin. The co-modified lignin was then introduced into freezing activated wood fibers to prepare the environment-friendly medium density fiberboard (MDF). The effect of co-modified lignin content on the properties of MDF was investigated. MDF with 3 wt% co-modified lignin exhibited the best comprehensive performance with the modulus of elasticity (MOE) of 5809 MPa, modulus of rupture (MOR) as high as 70 MPa, internal bonding strength (IB) of 2.29 MPa and thickness swelling (TS) as low as 16.65%, completely matching the requirements of the Chinese national standard GB/T 11718-2009 and EU national standard BS EN 622–5–2009. The interaction mechanism of co-modified lignin on the wood fibers was further explored by Fourier infrared spectroscopy (FTIR), differential scanning calorimeter (DSC) and scanning electron microscope (SEM) analysis. The phenolic structures of co-modified lignin could be chemically crosslinked with wood fibers during the hot-pressing process and the large amount of hydroxyl groups provided strong hydrogen bond interactions for the glue-free fiberboard. The glue-free fiberboard enhanced by co-modified lignin with excellent comprehensive performance exhibits a broad application prospect.11MDF: medium density fiberboard; MOR: modulus of rupture; MOE: modulus of elasticity; IB: internal bonding strength; TS: thickness expansion; DSC: differential scanning calorimetry

Effective and Selective Removal of Phosphate from Wastewater Using Guanidinium-Functionalized Polyelectrolyte-Modified Electrodes in Capacitive Deionization

The potential phosphorus shortage along with phosphorus pollution has drawn global attention, calling for effective technologies for phosphorus removal and recovery from wastewater. Capacitive deionization (CDI) is a promising technology for salt removal and nutrient recovery. However, their performances suffer from limited ion storage capacity and low selectivity, e.g., phosphate removal was lower than the other salts. Herein, guanidinium-functionalized polyelectrolyte-coated carbon nanotube (Gu-PAH/CNT) electrodes were prepared through the self-assembly technique. The Gu-PAH/CNT electrodes selectively adsorbed phosphate ions and prevented the repulsion of coions due to the combined effect of the ion-selective polyelectrolyte layer and the NH protons of Gu groups, resulting in strong electrostatic and hydrogen-bond interactions with phosphate ions. The Gu-PAH/CNT anode was coupled with a COOH-CNT cathode for selective capture of phosphate in a CDI device. The phosphate ion adsorption capacity of Gu-PAH/CNT electrodes is up to 23–30 mg PO43– g–1 in a phosphate solution with a wide pH range and mixtures (NaH2PO4/NaCl, NaH2PO4/Na2SO4, and NaH2PO4/NaNO3) at 1.2 V, presenting superior electroadsorption capacity, phosphate selectivity, and stable regeneration property. These encouraging results demonstrate that functionalized polyelectrolyte-modified electrode materials act as powerful platforms for effective and selective removal and recovery of specific contaminants from wastewater.

Characterization of Novel Solid Dispersions of Moringa oleifera Leaf Powder Using Thermo-Analytical Techniques

Moringa oleifera leaf powder (MOLP) has been identified as the most important functional ingredient owing to its rich nutritional profile and healthy effects. The solubility and functional properties of this ingredient can be enhanced through solid dispersion technology. This study aimed to investigate the effects of polyethylene glycols (PEGs) 4000 and 6000 as hydrophilic carriers and solid dispersion techniques (freeze-drying, melting, solvent evaporation, and microwave irradiation) on the crystallinity and thermal stability of solid-dispersed Moringa oleifera leaf powders (SDMOLPs). SDMOLPs were dully characterized using powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). The PXRD results revealed that the solid dispersions were partially amorphous with strong diffraction peaks at 2θ values of 19° and 23°. The calorimetric and thermogravimetric curves showed that PEGs conferred greater stability on the dispersions. The FTIR studyrevealed the existence of strong intermolecular hydrogen bond interactions between MOLP and PEG functional groups. MOLP solid dispersions may be useful in functional foods and beverages and nutraceutical formulations.

Fabrication of polyurethane porous composite films using biomass-based Juncus effusus fibers for oil removal from water

Oil spills cause serious ecological threats to aquatic life. High-performance polymer composite films using biomass fibers for rapidly removing oil from wastewater are exceptionally attractive due to sustainable development and high efficiency. Herein, we report a novel polymer composite film composed of polyurethane (PU) and biomass-based Juncus effusus (JE), which was fabricated using the nonsolvent induced phase separation method. The Juncus effusus/polyurethane (JEPU) composite films exhibited a highly controllable porous structure with the addition of JE powders. Owing to the strong hydrogen-bond interactions between biomass JE and PU matrix, the JEPU composite films showed good interface compatibility and enhanced mechanical property. Tensile stress-strain measurements demonstrated that the 2%JEPU showed tensile strength and strain of 1.14 MPa and 280.61%, respectively. Furthermore, the JEPU composites possess desirable hydrophobicity/oleophilicity with a water contact angle of 127°, exhibiting a good oil absorption capacity. The developed JEPU composite films may broaden the application range of industrial crops and products in eliminating oil contaminants from water.

KOH/thiourea aqueous solution: A potential solvent for studying the dissolution mechanism and chain conformation of corn starch

Non-derivatizing, high-efficiency and low-toxicity solvents are important for studying the dissolution behavior and potential applications of starch. In this study, we investigated the starch dissolution mechanism and molecular conformation in KOH/thiourea aqueous solutions and compared these with KOH/urea and KOH aqueous solutions. Solubility analysis revealed that the KOH/thiourea solution demonstrates a better ability to dissolve corn starch than KOH/urea and KOH solutions. Rheological behavior and dynamic and static light scattering indicated that starch is stable in KOH/thiourea solution and exists as a regular star structure. Fourier transform infrared spectroscopy, 13C NMR, and molecular dynamics simulations indicated that hydrated K+ and OH− destroy the strong starch hydrogen bond interactions; thiourea hydrate self-assembles into a shell surrounding the starch-KOH complex through interaction with KOH, whereas there is no direct strong interaction between urea and KOH. Therefore, adding thiourea to a KOH solution can promote dissolution and prevent self-aggregation of the starch chain.

Highly fluorescent polyethylene glycol-ascorbic acid complex for imaging and antimicrobial therapeutics

In this report, a facile and eco-friendly method was developed to synthesize a potent antimicrobial agent, effective against fungus, bacteria, and virus. The biocompatible FDA approved polymer, polyethylene glycol (PEG), has been modified by ascorbic acid to form fluorescent polyethylene glycol-ascorbic acid complex (FL PEG AA). The flourescence of FL PEG AA complex could be tuned from green to red in the visible range with varying ascorbic acid(AA) concentrations. The Density Functional Theory (DFT) and the Time-Dependent Density Functional Theory (DT-DFT) on ascorbic acid–monoethylene glycol and ascorbic acid–hexaethylene glycol studies were performed to understand the electronic and bonding nature of FL PEG-ascorbic acid (FL PEG AA) system. The emission of FL PEG AA can be ascribed to the integrated core of FL PEG AA through strong hydrogen-bonding interactions. The fluorescence of FL PEG AA was successfully applied to understand its cellular uptake by breast cancer cells. The FL PEG AA complex showed significant inhibition of growth, when tested against fungus (Candida albicans), bacteria: gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) and the virus (Bacteriophage lambda). The antimicrobial activity of the FL PEG AA system supports the application of this novel formulation as a potent antimicrobial agent. Due to its viscous physical nature, the FL PEG AA complex could be applied as a coating agent or aerosol spray.

A simple but effective ferrocene-based dual-channel colorimetric acetate electro-optical chemosensor

Acetate is one of the carboxylate anions with the unique trigonal chemical structure, which can form strong hydrogen-bond interaction with hydrogen-bond donors. In this sense, designing receptors that can recognize and sense the acetate ion at very low levels is thought to be more and more important. A novel and simple ferrocene-based colorimetric chemosensor (E)-1-(ferrocenyl)-2-(2,4-dinitrophenyl)hydrazine (denoted below as Sensor 1) for acetate ion detection bearing hydrazone N–H group as the binding site has been successfully prepared and spectroscopically characterized. The anion recognition via hydrogen-bonding interaction was investigated by electrochemistry and UV–Vis spectroscopic measurements. Sensor 1 realized dual-channel recognition with remarkable selectivity towards acetate over other anions. In particular, the recognition process of acetate ion could be easily accompanied by a visual color change from light yellow to purple, which allowed for quick and simple “naked-eyes” detection without resorting to spectroscopic instrumentation. The binding mechanism was revealed as the hydrogen interaction between Sensor 1 and acetate ion, with binding constant of (4.95±0.12) × 105 M−1 and detection limit of 0.84±0.03 µM (corresponding to 45.05±1.61 ppb) in dimethyl sulphoxide.

Catalytic oxidation of styrene by dinuclear Mn(III) coordination compound with asymmetric tridentate half-Salen type NNO-donor ligand

A new methoxo bridged dinuclear Mn(III) coordination compound, [Mn2(µ-OMe)2(L)2(MeOH)2]Cl2∙2MeOH (1), with tridentate N2O-donor half-Salen ligand was synthesized by the reaction of MnCl2·4H2O and (Z)-3-((2-aminocyclohexyl)amino)-1-phenylbut-2-en-1-one (HL) in methanol and characterized by spectroscopic methods and elemental analysis. The structure of compound 1 was also determined by single crystal X-ray diffraction studies which indicated it is a dinuclear Mn(III) coordination compound. Two Mn(III) are connected together by two methoxo bridges and have distorted octahedral geometry. The coordination compound is ionic and two chloride anions appear as the counter anions which are involved in strong hydrogen bond interactions. The catalytic activity of compound 1 was investigated in oxidation of styrene in the presence of hydrogen peroxide as a green oxidant. The effects of influencing parameters like molar ratio of the reagents, temperature and the presence of different solvents were investigated. The results of catalytic studies indicated the selectivity and activity of this catalytic system considerably depend on the reaction condition. Temperature and molar ratio of oxidant to substrate have high influence on both conversion and selectivity of the oxidation products. The best selectivity toward styrene epoxide was obtained at 40 °C and the best TOF was 66.4 h−1. The results indicate half-salen Mn(III) coordination compound can act as selective and efficient catalyst for oxidation of styrene under mild condition

Functional and structural analysis of catabolite control protein C that responds to citrate

Catabolite control protein C (CcpC) belongs to the LysR-type transcriptional regulator (LTTR) family, which regulates the transcription of genes encoding the tricarboxylic acid branch enzymes of the TCA cycle by responding to a pathway-specific metabolite, citrate. The biological function of CcpC has been characterized several times, but the structural basis for the molecular function of CcpC remains elusive. Here, we report the characterization of a full-length CcpC from Bacillus amyloliquefaciens (BaCcpC-FL) and a crystal structure of the C-terminal inducer-binding domain (IBD) complexed with citrate. BaCcpC required both dyad symmetric regions I and II to recognize the citB promoter, and the presence of citrate reduced citB promoter binding. The crystal structure of CcpC-IBD shows two subdomains, IBD-I and IBD-II, and a citrate molecule buried between them. Ile100, two arginines (Arg147 and Arg260), and three serines (Ser129, Ser189, and Ser191) exhibit strong hydrogen-bond interactions with citrate molecules. A structural comparison of BaCcpC-IBD with its homologues showed that they share the same tail-to-tail dimer alignment, but the dimeric interface and the rotation between these molecules exhibit significant differences. Taken together, our results provide a framework for understanding the mechanism underlying the functional divergence of the CcpC protein.

Characterization of a natural biodegradable edible film obtained from arrowroot starch and iota-carrageenan and application in food packaging

Future food packaging trends are shifting to natural and eco-friendly materials developed from biopolymers such as starch and other hydrocolloids, to reduce pollution from synthetic polymers. Arrowroot starch (AS) (3.5, 3, 2.5, and 2%) and iota-carrageenan (IC) (0.5, 1, 1.5, and 2%) were blended to develop biodegradable edible films (AS/IC-BEF), which were compared against AS-BEF (4%, control). All films were characterized based on their physico-mechanical and barrier properties, functional group properties, crystallinity properties, thermal properties, and soil and seawater biodegradation. AS-BEF exhibited smooth surface, high transparency, and completed composting soil biodegradation in 7 days whereas AS/IC-BEF samples exhibited higher tensile strength, water solubility, swelling properties, and barrier properties, but completed biodegradation after 30 days. XRD analysis indicated IC fractions contributed to increase in degree of crystallinity (28.35°) and FTIR signaled strong hydrogen bond interactions between polymers. AS/IC-BEF samples demonstrated melting temperatures between 158 and 190 °C while glass transition temperatures ranged from 153 to 176 °C, which resulted in maximum weight loss around 50–55% at melting temperatures. Finally, AS/IC-BEF samples successfully inhibited weight loss of cherry tomatoes at room temperature and extended their shelf life to 10 days, which indicated that the AS/IC composite material produced a BEF with potential food and industrial applications.

Synthesis and Molecular Docking Studies of some Pyrano[2,3-c] Pyrazole as an Inhibitor of SARS-Coronavirus 3CL Protease

The widespread global COVID-19 pandemic due to the lack of specific treatment and the urgent situation requires the use of all resources to remedy this scourge. The current study aimed to use molecular docking tools to find potential drug candidates for treatment. The pyrano[2,3-c] pyrazole 5(a-e) was targeted against the Main protease (Mpro), which plays a vital role in the replication and transcription of the Corona viral genome. The 3CL Protease (PDB ID 6LU7) was modeled, and the compounds were docked using Autodock Vina software, and ADMET data have been studied. All synthesized compounds were well engaged into the active site of the main protease with strong hydrogen bond interaction and a good score of energy. The 5b have been classed as the best inhibitor with an energy score of -6.2 kcal/mol, similar to the one given by chloroquine (-6.2Kcal/mol). Moreover, the molecular interaction studies showed that protease structure had multiple active site residues for all studied compounds. Our finding confirms the potential of these derivatives as lead compounds against the selected target protein of coronavirus, which needs further analysis and dynamic simulation studies to propose then develop a new antiviral treatment.

Comprehensive sequence and structure analysis of algal lipid catabolic enzyme Triacylglycerol lipase: an in silico study to vitalize the development of optimum engineered strains with high lipid productivity

Microalgae as an alternative renewable resource for biofuel production have captured much significance. Nonetheless, its economic viability is a field of major concern for researchers. Unraveling the lipid catabolic pathway and gaining insights into the sequence-structural features of its primary functioning enzyme, Triacylglycerol lipase, will impart valuable information to target microalgae for augmented lipid content. In the present study, a genome-wide comparative study on putative Triacylglycerol lipase (TAGL) enzyme from algal species belonging to varied phylogenetic lineages was performed. The comprehensive sequence analysis revealed that TAGL comprises of three distinct conserved domains, such as, Patatin, Class III Lipase, and Abhydro_lipase, and also confirmed the ubiquitous presence of GXSXG motif in the sequences analyzed. In the absence of a crystal structure of algal TAGL till date, we developed the first 3D model of patatin domain of TAGL from an oleaginous microalga, Phaedactylum tricornutum, employing homology modeling, docking and molecular dynamic simulations methods. The domain-substrate complex having the low-ranking docking score revealed the binding of palmitic acid to the TAGL patatin domain surface with strong hydrogen bond interactions. The simulation results implied that the substrate-complexed patatin domain and the free enzyme adopted a more stable conformation after 40 ns. This is the first ever attempt to provide in-silico insights into the structural and dynamical insights on catalytic mechanism of the TAGL patatin domain. Subsequently, these findings aided our understanding on their structural stability, folding mechanism and protein-substrate interactions, which could be further utilized to design site-specific mutagenic experiments for engineering microalgal strains. Communicated by Ramaswamy H. Sarma