Formation Of Hydrogen Bonds Research Articles

Chitosan/magnetic chitin nanowhisker polyelectrolyte membrane for direct methanol fuel cell applications: preparation, characterization, and performance analysis

ABSTRACT A hybrid chitosan-based nanocomposite was fabricated by chitin nanowhiskers coupled with silanized Fe3O4 nanoparticles as a polyelectrolyte membrane for direct methanol fuel cells (DMFCs). The morphological evaluations articulated that the magnetite nanoparticles were uniformly attached to the chitin nanowhiskers. After characterization of the synthesized nanowhiskers, they were incorporated into the chitosan, as a polycationic electrolyte, to investigate the performance of nanocomposite for DMFC applications. An external magnetic field was applied to the magnetic chitin nanowhiskers to induce alignment, and the effects of aligned nanowhiskers, as well as random ones, were also studied. The magnetic chitin nanowhiskers positively influenced the water uptake and proton conductivity due to the formation of hydrogen bonds between the surface functional groups of nanowhiskers and free water molecules. On the other hand, methanol permeation of the chitosan nanocomposites was reduced regarding the tortuous pathways and narrower transportation channels by the presence of nanowhiskers.

Structural Characterization of Pyruvic Acid Dimers Formed inside Helium Nanodroplets by Infrared Spectroscopy and Ab Initio Study.

The structural arrangements of α-keto acid complexes hold significant interest across various fields of chemistry such as enzyme modeling, drug design, or polymer blending. Herein, we report mass-selective infrared (IR) spectra of pyruvic acid monomers and dimers in the range 1720-1820 cm-1 recorded in helium nanodroplets at 0.37 K. The monomer features IR bands at 1807.1 and 1734.5 cm-1, which are assigned to the carboxylic and ketonic C═O stretching vibrations, respectively. Furthermore, the pyruvic acid dimers generated inside the helium nanodroplets are characterized by carboxylic and ketonic C═O stretch vibrations appearing at 1799.2 and 1737.0 cm-1, respectively. This frequency shift of ±7 cm-1 for both C═O stretching bands from the monomer to the dimer demonstrates that the structural motif of the monomer is maintained upon dimer aggregation in helium nanodroplets. The structural assignments were supported by a comparison of the MP2/aug-cc-pVDZ-predicted harmonic vibrational spectra at the C═O stretching region with the experiments. The global minimum monomer structure with an intramolecular hydrogen bond and its dimer stabilized by both inter- and intramolecular hydrogen bonding interactions reproduce the experimental spectra from the monomer and dimer. This assigned dimer structure lies ca.11 kJ/mol above the corresponding global minimum and is favored in helium nanodroplets due to the long-range realignment of molecules via dipole-dipole interaction, followed by short-range stabilization upon intermolecular hydrogen bond formation. The barrier for reconfiguration of the precooled monomer conformer leading to the formation of the most stable dimer structure is around 58 kJ/mol, which is infeasible at 0.37 K.

Introducing Hydrogen-Bonding Microenvironment in Close Proximity to Single-Atom Sites for Boosting Photocatalytic Hydrogen Production.

Inspired by enzymatic catalysis, it is crucial to construct hydrogen-bonding-rich microenvironment around catalytic sites; unfortunately, its precise construction and understanding how the distance between such microenvironment and catalytic sites affects the catalysis remain significantly challenging. In this work, a series of metal-organic framework (MOF)-based single-atom Ru1 catalysts, namely, Ru1/UiO-67-X (X = -H, -m-(NH2)2, -o-(NH2)2), have been synthesized, where the distance between the hydrogen-bonding microenvironment and Ru1 sites is modulated by altering the location of amino groups. The -NH2 group can form hydrogen bonds with H2O, constituting a unique microenvironment that causes an increased water concentration around the Ru1 sites. Remarkably, Ru1/UiO-67-o-(NH2)2 displays a superior photocatalytic hydrogen production rate, ∼4.6 and ∼146.6 times of Ru1/UiO-67-m-(NH2)2 and Ru1/UiO-67, respectively. Both experimental and computational results suggest that the close proximity of amino groups to the Ru1 sites in Ru1/UiO-67-o-(NH2)2 improves charge transfer and H2O dissociation, accounting for the promoted photocatalytic hydrogen production.

Structural and Electronic Evolution of Ethanolamine upon Microhydration: Insights from Hyperfine Resolved Rotational Spectroscopy.

Ethanolamine hydrates containing from one to seven water molecules were identified via rotational spectroscopy with the aid of accurate quantum chemical methods considering anharmonic vibrational corrections. Ethanolamine undergoes significant conformational changes upon hydration to form energetically favorable hydrogen bond networks. The final structures strongly resemble the pure (H2O)3-9 complexes reported before when replacing two water molecules by ethanolamine. The 14N nuclear quadrupole coupling constants of all the ethanolamine hydrates have been determined and show a remarkable correlation with the strength of hydrogen bonds involving the amino group. After addition of the seventh water molecule, both hydrogen atoms of the amino group actively contribute to hydrogen bond formation, reinforcing the network and introducing approximately 21-27% ionicity towards the formation of protonated amine. The findings highlight the critical role of microhydration in altering the electronic environment of ethanolamine, enhancing our understanding of amine hydration dynamics.

Regulating ion transport in lithium metal batteries via metal‐organic frameworks electrolyte modulator

AbstractLow Li+ transference number in liquid electrolytes can lead to uneven lithium deposition and dendrite growth, reducing coulombic efficiency and cycle life of lithium metal batteries. In this study, metal‐organic frameworks (MOFs) are used as electrolyte modulator to regulate Li+ transport. The ‐NH2 group introduced into MOFs can form hydrogen bonds with anions in the electrolyte, immobilizing these anions and thereby facilitating the migration of cations. As a result, a uniform and dense deposition morphology of lithium was achieved. The Li+ transference number is increased from 0.26 to 0.57. The assembled Li||Li symmetrical cell can stably cycle for over for 900 h with an average overpotential below 20 mV. In addition, the rate performance of the battery can be enhanced.

Temperature-Tolerant Versatile Conductive Zwitterionic Nanocomposite Organohydrogel toward Multisensory Applications.

Conductive hydrogels (CHs) are emerging materials for next generation sensing systems in flexible electronics. However, the fabrication of competent CHs with excellent stretchability, adhesion, self-healing, photothermal conversion, multisensing, and environmental stability remains a huge challenge. Herein, a nanocomposite organohydrogel with the above features is constructed by in situ copolymerization of zwitterionic monomer and acrylamide in the existence of carboxylic cellulose nanofiber-carrying reduced graphene oxide (rGO) plus a solvent displacement strategy. The synergy of abundant dipole-dipole interactions and intermolecular hydrogen bonds enables the organohydrogel to exhibit high stretchability, strong adhesion, and good self-healing. The presence of glycerol weakens the formation of hydrogen bonds between water molecules, endowing the organohydrogel with excellent environmental stability (-40 to 60 °C) to adapt to different application scenarios. Importantly, the multimodal organohydrogel presents excellent sensing behavior, including a high gauge factor of 16.3 at strains of 400-1440% and a reliable thermal coefficient of resistance (-4.2 °C-1) over a wide temperature widow (-40 to 60 °C). Moreover, the organohydrogel displays a highly efficient and reliable photothermal conversion ability due to the favorable optical absorbing behavior of rGO. Notably, the organohydrogel can detect accurate human activities at ambient temperature, demonstrating potential applications in flexible intelligent electronics.

Probing the Effects of Size and Charge on the Monohydration and Dihydration of SiF5- and SiF62- via Comparisons with BF4- and PF6.

This study systematically examines the interactions of the trigonal bipyramidal silicon pentafluoride and octahedral silicon hexafluoride anions with either one or two water molecules, (SiF5-(H2O)n and SiF62-(H2O)n, respectively, where n = 1, 2). Full geometry optimizations and subsequent harmonic vibrational frequency computations are performed using the CCSD(T) ab initio method with a triple-ζ correlation consistent basis set augmented with diffuse functions on all non-hydrogen atoms (cc-pVTZ for H and aug-cc-pVTZ for Si, O, and F; denoted as haTZ). Two monohydrate and six dihydrate minima have been identified for the SiF5-(H2O)n systems, whereas one monohydrate and five dihydrate minima have been identified for the SiF62-(H2O)n systems. Both monohydrated anions have a minimum in which the water molecule adopts a symmetric double ionic hydrogen bond (DIHB) motif with C2v symmetry. However, a second unique monohydrate minimum has been identified for SiF5- in which the water molecule adopts an asymmetric DIHB motif along the edge of the trigonal bipyramidal anion between one axial and one equatorial F atom. This Cs structure is more than 2 kcal mol-1 lower in energy than the C2v local minimum at the CCSD(T)/haTZ level of theory. While the interactions between the solvent and ionic solute are quite strong for the monohydrated anions (electronic dissociation energies of ≈12 and ≈24 kcal mol-1 for the SiF5-(H2O)1 and SiF62-(H2O)1 global minima, respectively), these values are nearly perfectly doubled for the dihydrates, with the lowest-energy SiF5-(H2O)2 and SiF62-(H2O)2 minima exhibiting dissociation energies of ≈24 and ≈47 kcal mol-1, respectively. Structures that form hydrogen bonds between the solvating water molecules also exhibit the largest shifts in the harmonic OH stretching frequencies for the waters of hydration. These shifts can exceed -100 cm-1 for the SiF5-(H2O)2 minimum and -300 cm-1 for the SiF62-(H2O)2 minimum relative to an isolated H2O molecule at the CCSD(T)/haTZ level of theory. This work also corrects the OH stretching frequency shifts for two dihydrate minima of PF6- that were previously erroneously reported ( J. Phys. Chem. A 2020, 124, 8744-8752, DOI: 10.1021/acs.jpca.0c06466).

Multi-spectral and docking assessments to explore the combination of an antiviral drug, entecavir with bovine serum albumin

Molecular interaction of entecavir (ETV) with the transport protein, albumin from bovine serum (BSA) was explored through multispectral and molecular docking approaches. The BSA fluorescence was appreciably quenched upon ETV binding and the quenching nature was static. The ETV–BSA complexation and the static quenching process were further reiterated using UV–visible absorption spectra. The binding constant (Ka) values of the complex were found as 1.47 × 104–4.0 × 103 M−1, which depicting a modarate binding strength in the ETV–BSA complexation. The experimental outcomes verified that the stable complexation was primarily influenced by hydrophobic interactions, hydrogen bonds and van der Waals forces. Synchronous and 3-D fluorescence spectral results demonstrated that ETV had significant impact on the hydrophobicity and polarity of the molecular environment near Tyr and Trp residues. Competitive site-markers displacement (with warfarin and ketoprofen) results discovered the suitable binding locus of ETV at site I in BSA. The molecular docking assessments also revealed that ETV formed hydrogen bonds and hydrophobic interactions with BSA, predominantly binding to site I (sub-domain IIA) of BSA.

Impact of solvation on the photoisomerisation dynamics of a photon-only rotary molecular motor

The optimization of the quantum efficiency of single-molecule light-driven rotary motors typically relies on chemical modifications. While, in isolated conditions, computational methods have been frequently used to design more efficient motors, the role played by the solvent environment has not been satisfactorily investigated. In this study, we used multiscale nonadiabatic molecular dynamics simulations of the working cycle of a 2-stroke photon-only molecular rotary motor. The results, which display dynamics consistent with the available transient spectroscopy measurements, predict a considerable decrease in the isomerisation quantum efficiency in methanol solution with respect to the gas phase. The origin of such a decrease is traced back to the ability of the motor to establish hydrogen bonds with solvent molecules. The analysis suggests that a modified motor with a reduced ability to form hydrogen bonds will display increased quantum efficiency, therefore extending the set of engineering rules available for designing light-driven rotary motors.

Synergistic structure engineering and electrochemical activation modulating vanadium oxide cathode toward superior zinc-ion storage

Aqueous zinc-ion batteries (ZIBs) have emerged as competitive systems for grid-scale energy storage due to their high safety and low cost. However, the lack of suitable high-performance cathode composites limits the practical progress of ZIBs. Herein, a novel cathode material, ammonium cation-inserted and oxygen vacancy co-modulated VO2 (named NVE), was firstly synthesized through the ethylene glycol (EG) sacrificial solvent-assisted structure transformation with the ammonium vanadate (named NV) as the precursor. The sacrificial solvent promotes the structural transformation of ammonium vanadate to NH4+-intercalated vanadium oxide and enhances the number of oxygen vacancies in the resulting material. Moreover, the electrochemical activation process was performed for in-situ construction of NH4+-inserted hydrated vanadium oxide (V2O5·nH2O) material. The electrochemical activation process with high anodic voltage enables multiple electron reactions, increasing the utilization of vanadium elements and achieving high capacity. Additionally, the formed hydrogen bonds between the V-O host and inserted NH4+ ions can enhance the structural integrity, while the oxygen vacancies decrease the interaction between the V-O host and inserted Zn2+ ions to boost ion diffusion. Consequently, the resulting activated cathode demonstrates higher capacity (441 mAh/g at 0.1 A/g), superior cycling durability (85.6 % retention over 4000 cycles), and exceptional rate capability (205 mAh/g at 20 A/g). Besides, the fabricated devices based on the activated NVE cathode show decent capacity and excellent flexible stability. Furthermore, the reversible electrochemical Zn2+ storage mechanism upon battery cycling was evaluated by several kinetic measurements and in/ex-situ characterizations. This work provides novel perspectives for the fabrication of advanced cathode materials for superior aqueous ZIBs.

Insight into binding of endogenous neurosteroid ligands to the sigma-1 receptor

The sigma-1 receptor (σ1R) is a non-opioid membrane receptor, which responds to a diverse array of synthetic ligands to exert various pharmacological effects. Meanwhile, candidates for endogenous ligands of σ1R have also been identified. However, how endogenous ligands bind to σ1R remains unknown. Here, we present crystal structures of σ1R from Xenopus laevis (xlσ1R) bound to two endogenous neurosteroid ligands, progesterone (a putative antagonist) and dehydroepiandrosterone sulfate (DHEAS) (a putative agonist), at 2.15-3.09 Å resolutions. Both neurosteroids bind to a similar location in xlσ1R mainly through hydrophobic interactions, but surprisingly, with opposite binding orientations. DHEAS also forms hydrogen bonds with xlσ1R, whereas progesterone interacts indirectly with the receptor through water molecules near the binding site. Binding analyses are consistent with the xlσ1R-neurosteroid complex structures. Furthermore, molecular dynamics simulations and structural data reveal a potential water entry pathway. Our results provide insight into binding of two endogenous neurosteroid ligands to σ1R.

Aloe vera mucilage loaded gelatin electrospun fibers contained in polylactic acid coaxial system and polylactic acid and poly(e-caprolactone) tri-layer membranes for tissue engineering.

Polymeric electrospun mats have been used as scaffolds in tissue engineering for the development of novel materials due to its characteristics. The usage of synthetic materials has gone in decline due to environmental problems associated with their synthesis and waste disposal. Biomaterials such as biopolymers have been used recently due to good compatibility on biological applications and sustainability. The purpose of this work is to obtain novel materials based on synthetic and natural polymers for applications on tissue engineering. Aloe vera mucilage was obtained, chemically characterized, and used as an active compound contained in electrospun mats. Polymeric scaffolds were obtained in single, coaxial and tri-layer structures, characterized and evaluated in cell culture. Mucilage loaded electrospun fibers showed good compatibility due to formation of hydrogen bonds between polymers and biomolecules from its structure, evidenced by FTIR spectra and thermal properties. Cell viability test showed that most of the obtained mats result on viability higher than 75%, resulting in nontoxic materials, ready to be used on scaffolding applications. Mucilage containing fibers resulted on materials with potential use on scaffolding applications due to their mechanical performance and cell viability results.

Discovery of a Series of 4-Amide-thiophene-2-carboxyl Derivatives as Highly Potent P2Y14 Receptor Antagonists for Inflammatory Bowel Disease Treatment.

The P2Y14 receptor has been proven to be a potential target for IBD. Herein, we designed and synthesized a series of 4-amide-thiophene-2-carboxyl derivatives as novel potent P2Y14 receptor antagonists based on the scaffold hopping strategy. The optimized compound 39 (5-((5-fluoropyridin-2-yl)oxy)-4-(4-methylbenzamido)thiophene-2-carboxylic acid) exhibited subnanomolar antagonistic activity (IC50: 0.40 nM). Moreover, compound 39 demonstrated notably improved solubility, liver microsomal stability, and oral bioavailability. Fluorescent ligand binding assay confirmed that 39 has the binding ability to the P2Y14 receptor, and molecular dynamics (MD) simulations revealed the formation of a unique intramolecular hydrogen bond (IMHB) in the binding conformation. In the experimental colitis mouse model, compound 39 showed a remarkable anti-IBD effect even at low doses. Compound 39, with a potent anti-IBD effect and favorable druggability, can be a promising candidate for further research. In addition, this work lays a strong foundation for the development of P2Y14 receptor antagonists and the therapeutic strategy for IBD.

Exploring the AC conductivity and dielectric properties of PVA films doped with Erythrosin B.

Abstract Erythrosin B (EB) doped in PVA film was processed utilizing the casting procedure, and the structure was investigated via the Fourier Transformation infrared technique (FTIR). FTIR analysis presented a strong formation of intermolecular hydrogen bonds among PVA and EB hydroxyl groups (OH). Characteristic temperature and frequency variation of dielectric behavior and AC electrical conductivity for films of PVA doped with Erythrosin B were analyzed at (293-383 K) temperature and (102-106 Hz) frequency. The AC conductivity dependency indicates that the predominant conduction mechanism in PVA doped with Erythrosin B films follows the correlated barrier hopping (CBH) model. The charge carriers' hopping involving localized states causes a relaxation process. Estimates were made for the AC conductivity activation energy and the conductivity relaxation energy. Frequency and temperature affect the dielectric constant (e/) and the dielectric loss (e//). The complex impedance spectrum (Z/ vs. Z//) showed single semicircular arcs with a decreased radius with increasing temperature. The relaxation peaks in the electric modulus representation are clearly defined, and the relaxation period has been calculated.

3D printable elastomers with exceptional strength and toughness.

Three-dimensional (3D) printing has emerged as an attractive manufacturing technique because of its exceptional freedom in accessing geometrically complex customizable products. Its potential for mass manufacturing, however, is hampered by its low manufacturing efficiency (print speed) and insufficient product quality (mechanical properties). Recent progresses in ultra-fast 3D printing of photo-polymers1-5 have alleviated the issue of manufacturing efficiency, but the mechanical performance of typical printed polymers still falls far behind what is achievable with conventional processing techniques. This is because of the printing requirements that restrict the molecular design towards achieving high mechanical performance. Here we report a 3D photo-printable resin chemistry that yields an elastomer with tensile strength of 94.6 MPa and toughness of 310.4 MJ m-3, both of which far exceed that of any 3D printed elastomer6-10. Mechanistically, this is achieved by the dynamic covalent bonds in the printed polymer that allow network topological reconfiguration. This facilitates the formation of hierarchical hydrogen bonds (in particular, amide hydrogen bonds), micro-phase separation and interpenetration architecture, which contribute synergistically to superior mechanical performance. Our work suggests a brighter future for mass manufacturing using 3D printing.

In Silico Drug Repurposing Against PSMB8 as a Potential Target for Acute Myeloid Leukemia Treatment.

PSMB8 emerges as a prominent gene associated with cancer survival, yet its potential therapeutic role in acute myeloid leukemia (AML) remains unexplored within the existing literature. The principal aim of this study is to systematically screen an expansive library of molecular entities, curated from various databases to identify the prospective inhibitory agents with an affinity for PSMB8. A comprehensive assortment of molecular compounds obtained from the ZINC15 database was subjected to molecular docking simulations with PSMB8 by usingtheAutoDock tool in PyRx (version 0.9.9) to elucidate binding affinities. Following the docking simulations, a select subset of molecules underwent further investigation through comprehensive ADMET (absorption, distribution, metabolism, excretion, and toxicity) analysis employing AdmetSar and SwissADME tools. Finally, RMSD, RMSF, Rg, and H bond analyses were conducted via GROMACS to determine the best conformationally dynamic molecule that represents the candidate agent for the study. Following rigorous evaluation, Adozelesin, Fiduxosin, and Rimegepant have been singled out based on considerations encompassing bioavailability scores, compliance with filter criteria, and acute oral toxicity levels. Additionally, ligand interaction analysis indicates that Adozelesin and Fiduxosin exhibit an augmented propensity for hydrogen bond formation, a factor recognized for its facilitative role in protein-ligand interactions. After final analyses, we report that Fiduxosin may offera treatment possibility by reversing the low survival rates caused by PSMB8 high activation in AML. This study represents a strategic attempt to repurpose readily available pharmaceutical agents, potentially obviating the need for de novo drug development, and thereby offering promising avenues for therapeutic intervention in specific diseases.

Optimization and Mechanistic Insight of Phenol Removal using an Effective Green Kaolin Adsorbent through Experimental and Computational Approaches

The discharge of phenols into the aquatic environment has detrimentally affected human health and the aquatic ecosystem. Hence, removing phenols from polluted water bodies has been a global concern. In this study, a natural and low-cost adsorbent, kaolin, was used to remove phenol from aqueous solutions. Experimental and computational approaches were applied to optimize the removal efficiency and provide mechanistic insight into the phenol removal process. Based on the response surface methodology findings, the optimum conditions were pH 1.6, 40 min, 50 mg/L, and 2 g with 92.19% maximum percentage removal. The regeneration test shows that kaolin retained over 76.76% of adsorption capacities. SEM and FESEM reveals the surface morphology and effectiveness of kaolin as phenol removal. The best fit for the Isotherm adsorption for the phenol on kaolin is Freundlich isotherm, which indicated multilayer adsorption. The hydroxyl group from phenol (-OH) and the siloxane group of kaolin (Si-O-Si) shifted, suggesting the presence of a hydrogen bond between kaolin and phenol during adsorption, as determined by one- and two-dimensional IR spectroscopy. Density functional theory calculations were used to support the experimental results by providing information on the Mulliken charge and electronic transition of the complex to improve understanding of the adsorption of phenol on kaolin. Based on the quantum theory of atoms in molecules analysis (QTAIM) and the reduced density gradient non-covalent interaction (RDG-NCI) technique, the chemical reaction occurring during the removal of phenol by kaolin was determined to occur through hydrogen bonding and classified as an intermediate type (∇2ρ(r) > 0 and H < 0). Further characterizations employing molecular electrostatic potential, global reactivity, and local reactivity descriptors were conducted to investigate the mechanism of the phenol adsorption on kaolin. The findings demonstrated that phenol functions as an electrophile while kaolin acts as a nucleophile during the formation of hydrogen bonds, where the interaction occurred between the O2 atom of kaolin (electron donor) and the H13 atom of phenol (electron acceptor).

Construction of macromolecular structure model of Luling coal and study on the dynamic mechanism of micro-wetting process

The physicochemical structure and energy composition of coal macromolecules are the major factors affecting coal wettability. This study thus employed 13C-NMR, FTIR, and XPS to determine the chemical structure of coal in the No. 10 coal seam of the Luling coal mine and gain insights into the molecular mechanisms of coal wetting. The results showed that the molecular formula of the Luling 10 model was C290H223O25N5S. Through molecular dynamics simulation, upon the stable adsorption of sodium dodecyl sulfate (SDS) on the coal surface, both the mobility of water molecules and the water molecule content in the interfacial adsorption layer increased. After SDS was added, except for the hydrogen bond energy, the increase rate of each potential energy increased, and van der Waals energy and bond length energy changed the most. The reason for the decrease of hydrogen bond energy is that more atoms in coal macromolecules form hydrogen bonds with polar water molecules. The increase of SDS promoted the significant changes of bond length energy, bond angle energy and van der Waals force of coal, thus increasing the wettability of coal. Taken together, our findings provide important insights into the molecular mechanisms through which surfactants improve chemical wetting.

Antiasthamatic Activity of Betulinic Acid as a Current Bioactive Compound in an Experimental Model

aims: The purpose of this study was to assess BA&amp;#039;s effectiveness in treating bronchial asthma and to use molecular docking to find BA&amp;#039;s binding energy with β-adrenoceptor. background: The natural triterpenoid molecule betulinic acid (BA) has many biological and therapeutic uses, one of which is the relief of asthma symptoms. objective: The purpose of this study was to assess BA&amp;#039;s effectiveness in treating bronchial asthma and to use molecular docking to find BA&amp;#039;s binding energy with β-adrenoceptor. method: Methods: The extraction technique involved the use of ethanol as a solvent and the herb Bacopa monnieri. Budesenoid was used as a standard drug. AutoDock vina in PyRx 0.8 was used for the molecular docking investigation. An acute toxicity examination was conducted according to OECD guideline 425. A guinea pig model of asthma called anaphylactic microshock was employed to ascertain the antiasthmatic efficacy of the medication under investigation. Antiasthmatic activity was performed by dividing the animals into four groups each containing six animals. Group 1 was the control group received only vehicle. Group 2 was the standard group received budesenoid. Group 3 was the test group received B. monnieri extract. Group 4 was the test group received betulinic acid (BA). result: Results: In terms of binding affinity, BA has a value of -7.45 kcal/mol. In line with earlier findings, molecular docking showed that BA bound to the hydrophobic cavity of LOX-5, and the formation of hydrogen bonds altered the micro-environment and structure of LOX-5. This resulted in a reduction in enzyme activity. The mean pre-convulsion time for Drug-1 was 506.66 in comparison to the control group as observed in guinea pig model of asthma. conclusion: Conclusion: It may be a good analytical approach to test BA or BA derivatives with a stronger antiasthmatic profile with the help of computed properties. BA was found effective in reducing anaphylaxis in animal model, thus, it may be useful against asthma. other: Conclusion: It may be a good analytical approach to test BA or BA derivatives with a stronger antiasthmatic profile with the help of computed properties. BA was found effective in reducing anaphylaxis in animal model, thus, it may be useful against asthma.

Binding of steroid substrates reveals the key to the productive transition of the cytochrome P450 OleP.

OleP is a bacterial cytochrome P450 involved in oleandomycin biosynthesis as it catalyzes regioselective epoxidation on macrolide intermediates. OleP has recently been reported to convert lithocholic acid (LCA) into murideoxycholic acid through a highly regioselective reaction and to unspecifically hydroxylate testosterone (TES). Since LCA and TES mainly differ by the substituent group at the C17, here we used X-ray crystallography, equilibrium binding assays, and molecular dynamics simulations to investigate the molecular basis of the diverse reactivity observed with the two steroids. We found that the differences in the structure of TES and LCA affect the capability of these molecules to directly form hydrogen bonds with N-terminal residues of OleP internal helix I. The establishment of these contacts, by promoting the bending of helix I, fosters an efficient trigger of the open-to-closed structural transition that occurs upon substrate binding to OleP and contributes to the selectivity of the subsequent monooxygenation reaction.