Strong Hydrogen-bonding Interactions Research Articles

In silico modeling revealed phytomolecules derived from Cymbopogon citratus (DC.) leaf extract as promising candidates for malaria therapy

The emergence of varying levels of resistance to currently available antimalarial drugs significantly threatens global health. This factor heightens the urgency to explore bioactive compounds from natural products with a view to discovering and developing newer antimalarial drugs with novel mode of actions. Therefore, we evaluated the inhibitory effects of sixteen phytocompounds from Cymbopogon citratus leaf extract against Plasmodium falciparum drug targets such as P. falciparum circumsporozoite protein (PfCSP), P. falciparum merozoite surface protein 1 (PfMSP1) and P. falciparum erythrocyte membrane protein 1 (PfEMP1). In silico approaches including molecular docking, pharmacophore modeling and 3D-QSAR were adopted to analyze the inhibitory activity of the compounds under consideration. The molecular docking results indicated that a compound swertiajaponin from C. citratus exhibited a higher binding affinity (−7.8 kcal/mol) to PfMSP1 as against the standard artesunate-amodiaquine (−6.6 kcal/mol). Swertiajaponin also formed strong hydrogen bond interactions with LYS29, CYS30, TYR34, ASN52, GLY55 and CYS28 amino acid residues. In addition, quercetin another compound from C. citratus exhibited significant binding energies −6.8 and −8.3 kcal/mol with PfCSP and PfEMP1, respectively but slightly lower than the standard artemether-lumefantrine with binding energies of −7.4 kcal/mol against PfCSP and −8.7 kcal/mol against PfEMP1. Overall, the present study provides evidence that swertiajaponin and other phytomolecules from C. citratus have modulatory properties toward P. falciparum drug targets and thus may warrant further exploration in early drug discovery efforts against malaria. Furthermore, these findings lend credence to the folkloric use of C. citratus for malaria treatment. Communicated by Ramaswamy H. Sarma

Phase transition, optical, and elastic properties of a new hybrid organic–inorganic perovskite: [(R)-(+)-3-aminoquinuclidine]KI3

A new hybrid organic–inorganic perovskite, (R-3AQ)KI3 [R-3AQ2+ = (R)-(+)-3-aminoquinuclidine], has been synthesized and comprehensively characterized by experimental approaches and density functional theory calculations. Our experimental results demonstrate that (R-3AQ)KI3 has a typical perovskite structure and exhibits a reversible order–disorder phase transition at temperatures of 457 and 443 K on heating and cooling, respectively. Under ultraviolet irradiation, a clear yellowish-green emission peaked at 556 nm was observed for (R-3AQ)KI3. The calculated electronic structure shows that (R-3AQ)KI3 possesses a typical direct bandgap with a value of 3.74 eV and its valence band maximum and conduction band minimum primarily arise from the I-5p and I-5s orbitals, respectively. In addition, the elastic calculations indicate that (R-3AQ)KI3 displays a relatively large structure stiffness, relatively small elastic anisotropy, and fairly low acoustic velocity, owing to the rigid K–I bonds and the strong hydrogen bond interactions between the [KI3]2− perovskite framework and R-3AQ2+ cations. These results suggest that the mechanical robustness of this multifunctional (R-3AQ)KI3 makes it a good candidate material for sensing applications.

NMR and DFT studies of monounsaturated and ω-3 polyunsaturated free fatty acids in the liquid state reveal a novel atomistic structural model of DHA

Structures of low-energy conformers of caproleic acid (CA; 10:1 cis-9), oleic acid (OA; 18:1 cis-9), α-linolenic acid (ALA; 18:3 cis-9,12,15 ω-3), eicosapentaenoic acid (EPA; 20:5 cis-5,8,11,14,17 ω-3), and docosahexaenoic acid (DHA; 22:6 cis-4,7,10,13,16,19 ω-3) in the liquid state, based on detailed 1D NOE and density functional theory calculations of 1H NMR chemical shifts are presented. Transient 1D NOE experiments with variable mixing time showed significant through-space proximity of the CH2–COOH protons and the terminal CH3– groups. Variable temperature 1H NMR experiments revealed strong intermolecular centro-symmetric cyclic hydrogen bond interactions of the carboxylic groups of the monounsaturated oleic and caproleic acids (δ(COOH) ∼ 12.0–12.4 ppm), ALA and EPA (δ(COOH) ∼ 11.0 ppm). On the contrary, the carboxylic proton of DHA is strongly shielded with δ(COOH) ∼ 8.5 ppm. DFT calculations were interpreted in terms of aggregates of dimerized fatty acids with parallel and antiparallel interdigitated structures. The antiparallel arrangement was found to be in excellent agreement with experimental 1D NOE NMR data. For the dimeric DHA, a flip-flop process between a classical intermolecular centro-symmetric hydrogen bond through carboxylic groups and a novel intramolecular hydrogen bond between the carboxylic group and the terminal ω-3 double bond is demonstrated.

Comparative Study of Molecular Interaction of Quercetin and Imatinib with BCR-ABL Fusion Protein In-Silico for the Selective Anti-CML Activity of Quercetin

Aim: To study the comparative molecular interactions of Quercetin and Imatinib with the active sites of Breakpoint Cluster Region (BCR)-Abelson (ABL) fusion protein using molecular docking analysis for the selective anti-Chronic myeloid leukemia (CML) activity. Materials and Methods: In this study, Group 1 is binding affinity of Imatinib with BCR-ABL Fusion Protein and Group 2 is binding affinity of Quercetin with BCR-ABL Fusion Protein. The sample size was calculated with pretest power 80%. The sample size per group is 10 and total sample size is 20. The protein structure of BCR-ABL fusion protein was collected from the protein data bank (PDB) website and the ligand structures were collected from the NCBI-PUBCHEM website. The binding energy (kcal/mol) was calculated using Autodock Vina Software. The non-covalent protein ligand interactions were detected using protein–ligand interaction profiler (PLIP) webserver. Results: The mean binding affinity of Imatinib (-10.34 kcal/mol) was significantly (p=<0.001, p<0.001, 2-tailed t-test) higher than Quercetin (-8.8 kcal/mol) towards the active sites of BCR-ABL fusion protein. Conclusion: In Spite of lesser binding affinity of Quercetin compared to Imatinib, Quercetin can make strong hydrogen bond and hydrophobic interactions with the aminoacid residues at the active sites of BCR-ABL fusion protein. It suggests that, Quercetin may bind selectively to the cells of CML and inhibit their proliferation and can act as novel Anti-CML agent.

Comparative Study of Molecular Interactions of Thymol and Imatinib with BCR-ABL Fusion Protein In-Silico for the Selective Anti-CML Activity of Thymol

Aim: To study the comparative molecular interactions of Thymol and Imatinib with the active sites of Breakpoint Cluster Region (BCR)-Abelson (ABL) fusion protein using molecular docking analysis for the selective anti-Chronic myeloid leukemia (CML) activity. Materials and Methods: In this study, Group 1 is binding affinity of Imatinib with BCR-ABL Fusion Protein and Group 2 is binding affinity of Thymol with BCR-ABL Fusion Protein. The sample size was calculated with pretest power 80%. The sample size per group is 10 and total sample size is 20. The protein structure of BCR-ABL fusion protein was collected from the protein data bank (PDB) website and the ligand structures were collected from the NCBI-PUBCHEM website. The binding energy (kcal/mol) was calculated using Autodock Vina Software. Results: The mean binding affinity of Imatinib (-10.4 kcal/mol) was significantly (p=<0.001, p<0.001, 2-tailed t-test) higher than Thymol (-6.89 kcal/mol) towards the active sites of BCR-ABL fusion protein. Conclusion: In Spite of lesser binding affinity of Thymol compared to Imatinib, Thymol can make strong hydrogen bond and hydrophobic interactions with the aminoacid residues at the active sites of BCR-ABL fusion protein. It suggests that, thymol may bind selectively to the cells of CML and inhibit their proliferation and can act as novel Anti-CML agent.

Macroscale Superlubricity with Ultralow Wear and Ultrashort Running-In Period (∼1 s) through Phytic Acid-Based Complex Green Liquid Lubricants.

Liquid superlubricity has attracted much attention, due to its ability to significantly reduce friction on the macroscale. However, the severe wear caused by the long running-in period is still one of the bottlenecks restricting the practical application of liquid superlubricating materials. In this work, the obtained polyethylene glycol-phytic acid (PEG-PA) composite liquid lubricants showed outstanding superlubricating properties (μ ≈ 0.006) for Si3N4/glass friction pairs with an ultrashort running-in period (∼1 s) under high Hertzian contact pressure of ∼758 MPa. More importantly, even after up to 12 h (∼700 m of travel), only about 100 nm deep wear scars were found on the surface of the glass sheet (wear rate = 2.51× 10-9 mm3 N-1 m-1). From the molecular point of view, the water molecules anchored between the two friction pairs have extremely low shear force during the friction process, and the strong hydrogen bond interaction between PEG and PA greatly improves the bearing capacity of the lubricant. This work addresses the challenge of liquid superlubricant simultaneously exhibiting low shear force and high load-carrying capacity and makes it possible to obtain liquid superlubrication performance with an extremely short running-in time.

Design of a highly flexible, self-healing, conductive and antimicrobial hydrogel with organic-inorganic network structure

A simple strategy to develop a conductive and antimicrobial self-healing hydrogel with organic-inorganic network was more conducive to actual production and application. Herein, we report a simple strategy (one-pot radical polymerization) to prepare self-healing conductive hydrogels based on alkaline calcium bentonite (ACBt)/poly (acrylic acid) (PAA). The ACBt participated in the construction of organic-inorganic crosslinking networks of hydrogels through acid-base neutralization reactions between its active -Ca-OH group and acrylic acid. Additionally, ACBt, as an inorganic crosslinker, endows hydrogels with extraordinary sensing ability, and it does not require tedious organic modification. Thus, satisfactory mechanical properties were achieved, including excellent tensile strength of 0.74 MPa, high tensile strain of 3880%, and extraordinary toughness of 3.596 MJ/m3. Moreover, the abundant –COOH groups on the PAA chain could promote the strong hydrogen bond interaction between the organic-inorganic network structure, thus endowing the hydrogel with excellent self-healing ability. More importantly, the ACBt/PAA conductive hydrogels exhibit excellent antibacterial activity against Escherichia coli (Gram-negative bacteria) and Staphylococcus aureus (Gram-positive bacteria), which have potential applications as flexible antibacterial materials to monitor movements of the human body in real time.

Evaluation of Zerumbone as an EGFR Tyrosine Kinase Inhibitor by Molecular Docking Method

Objective: EGFR-TK domain is of great importance in the initiation and progression of various cancer types, especially lung cancer. The existing EGFR-TK inhibitors have numerous side effects, which make them improper to be utilized as cancer therapeutics. In this study, we aimed to analyze the activity of zerumbone as an anticancer agent targeting EGFR by molecular docking approach and to evaluate its activity in comparison with curcumin.
 Material and Method: MEP and HOMO-LUMO analyses were achieved at B3LYP/6-31G(D,P) level to evaluate electrostatic interactions that affect binding of EGFR with zerumbone and curcumin. Their binding energies were determined by molecular docking and compared with erlotinib as reference ligand.
 Result and Discussion: Docking studies showed higher bindings (lower binding energy) for curcumin and zerumbone with binding energies -8.0 and -7.6 kcal/mol, respectively, compared to erlotinib (-7.54 kcal/mol). However, there is no significant difference between them. The ΔE energy gap of zerumbone and curcumin were 5.09 and 3.68 eV which implies that these compounds have more stability but less electronegativity in comparison with erlotinib (ΔE=2.22eV). Also, zerumbone showed strong hydrogen bond interactions with EGFR, making it candidate as EGFR inhibitor, as did both in curcumin and erlotinib. It was concluded that zerumbone may have potential for inhibitory activity against EGFR-TK.

An imidazole based luminescent Zn (II) metal–organic framework for sensing of nitroaromatic explosives

The Zn(II)-based IFP-1 (IFP = imidazolate framework Potsdam) was successfully synthesized by solvothermal process to detect the nitroaromatic compounds (NACs) including nitrobenzene (NB), 1,3‑dinitrobenzene (1,3-DNB), 1,2‑dinitrobenzene (1,2-DNB), 1,4‑dinitrobenzene (1,4-DNB), 4‑nitrotoluene (4-NT) and 2,4,6-trinitrophenol (TNP). It was found that IFP-1 gives the maximum emission intensity at 338 nm upon excitation at 288 nm. The quenching constant (KSV) for all the analytes was found in the order as follows: TNP > DNP > NB > NT > 1,2-DNB > 1,4-DNB > 1,3-DNB. The localization of the amide group of 2-methylimidazolate-4-amide-5-imidate ligand in the walls of the channels provides feasible interacting sites for incoming analytes. These suitable geometrical characteristics of IFP-1 provide close proximity to NACs leading to their prompt sensing ability. The fluorescence intensity was reduced by 71 % in the presence of TNP. IFP-1 shows high selective detection of TNP even in presence of other nitroaromatic compounds. However, the sensing ability of IFP-1 towards TNP is highest over other NACs with high quenching constant (Ksv) of 1.12 × 105 M−1 and a low detection limit of 0.23 µM, indicating a good detection limit. A detailed investigation has been carried out on the fluorescence quenching mechanism by DFT calculation. This study showed that the high sensitivity of the compound towards TNP is possible because of the formation of non-fluorescent ground state complex formation driven by strong pi-pi stacking interaction and electrostatic hydrogen bond interactions.

Two-photon absorption of FAPbBr3 perovskite nanocrystals

Perovskite nanocrystals (NCs) with high two-photon absorption (TPA) cross-section are of great interest due to their potential applications in three-dimensional optical data storage and multiphoton fluorescence microscopy. Among various perovskite materials, FAPbBr3 NCs show a better development prospect due to their excellent stability. However, there are few reports on their nonlinear optical properties. In this work, the nonlinear optical behavior of FAPbBr3 NCs is studied. The methods of multiphoton absorption photoluminescence saturation and open aperture Z-scan technique were applied to determine the TPA cross-section of FAPbBr3 NCs, which was around 2.76 × 10−45 cm4⋅s⋅photon−1 at 800 nm. In addition, temperature-dependent photoluminescence induced by TPA was investigated, and the small longitudinal optical phonon energy and electron–phonon coupling strength was obtained, which confirm the weak Pb–Br interaction. Meanwhile, it is found that the exciton binding energy in FAPbBr3 NCs was 69.668 meV, which may be ascribed to the strong hydrogen bond interaction. It is expected that our findings will promote the application of FAPbBr3 NCs in optoelectronic devices.

Self-intercepting interference of hydrogen-bond induced flexible hybrid film to facilitate lithium extraction

Supported lithium-ion sieve (LIS) adsorbents have received widespread attention due to their excellent inherent adsorption potential toward lithium (Li) in the liquid Li source. However, LIS-based adsorbents still suffer from slow Li extraction rate and reduced Li selectivity caused by the embedding of the active sites and the adverse effects of high level of competing ions from the seawater/brine. Here, relying on the hydrogen bond (OMnO···HO) interaction, a LIS-based sandwich heterostructure is designed by the confinement of 0D MnO2·0.3H2O (HMO) nanoparticles into the interlayer of a flexible 2D MXene/1D cellulose nanofiber (MC) hybrid film (HMO@MC). Benefiting from the strong hydrogen bond interaction, the HMO@MC hybrid film achieves an excellent LIS utilization (up to 96 %) and a maximum Li adsorption capacity of 21.39 mg g−1, outperforming most LIS-based adsorbents. More impressively, the HMO@MC heavily reduces the Li migration barrier by self-intercepting interference through the steric hindrance effect of surface functional groups, thereby obtaining a fast Li adsorption rate (18.23 mg g−1 HMO, 12 h) and a super-high Li selectivity (e.g., Li/Na of 29231.8 and Li/Mg of 3605.9). This work offers a new adsorbent designing idea for Li extraction from liquid lithium source and will inspire more efforts in constructing LIS-based adsorbents for Li recovery.

Crystal structure, DFT, molecular docking and dynamics simulation studies of 4,4-dimethoxychalcone

In the current study, the compound 4,4-dimethoxychalcone (DMC) was structurally studied and analyzed by in silico approach against Mpro to investigate its inhibitory potential. The molecular structure of the compound was confirmed by the single crystal X-ray diffraction studies. The crystal structure packing is characterized by various hydrogen bonds, C-H…π and π…π stacking. Intermolecular interactions are quantified by Hirshfeld surface analysis and the electronic structure was optimized by DFT calculations; results are in agreement with the experimental studies. Further, DMC was virtually screened against SARS-CoV-2 main protease (PDB-ID: 6LU7) using molecular docking, and molecular dynamics (MD) simulations to identify its inhibitory potential. A significant binding affinity exists between DMC and Mpro with a -6.00 kcal/mol binding energy. A MD simulation of 30ns was carried out; the results predict DMC possessing strong binding affinity and hydrogen-bonding interactions within the active site during the simulation period. Therefore, based on the results of the current investigation, it can be inferred that a DMC molecule may be able to inhibit Mpro of COVID-19.

Thiourea-Catalyzed Amidation of Esters: A New Method for the Preparation of Amides

Abstract: Although amides are one of the most abundant bonds in biology and medicinal chemistry, methods to prepare them are still limited. To expand on current methods for the formation of amides bonds, organocatalysts (thiourea-based) were developed to mediate the conversion of esters to amides. The reactions proceed in good to moderate yields and tolerate a variety of functional groups. 1 H NMR titration and computational studies show a strong hydrogen-bonding interaction between the thiourea catalyst and the ester moiety. This hydrogen-bonding interaction is proposed to be the driving force for the amidation of esters.

Curcumin based pyrazole-thiazole hybrids as antiproliferative agents: Synthesis, pharmacokinetic, photophysical properties, and docking studies

A series of new curcumin pyrazole-thiazole hybrids (C1-C8) were synthesized and characterized by fundamental spectral analysis. The synthesized compounds were tested for antiproliferative activity against the colorectal cancer cell line (COLO-205), breast cancer cell line (MCF-7), liver cancer cell line (HepG-2), lung cancer cell line (A549), and cervical cancer cell line (HeLa) using cisplatin as a positive control. The compounds C7 (IC50 values of 8.57 ± 1.09 µM for COLO-205, 9.22 ± 0.73 µM for MCF-7, 16.95 ± 1.16 µM for HepG-2, 8.48 ± 1.36 µM for A549, and 7.22 ± 1.08 µM for HeLa), C2, and C5 displayed the most potent antiproliferative activity against the growth of all tested cell lines. For the three compounds (C2, C5, and C7), which were shown to have high in vitro anti-cancer activity, we have carried out a kinase inhibitory assay against the EGFR and HER2, where the compound C7 has exhibited double inhibitory potency towards the EGFR when compared to reference erlotinib. Furthermore, in silico molecular docking studies on EGFR (PDB ID: 4HJ0) and HER2 (PDB ID: 3P0Z) proteins revealed that the potent ligands exhibited higher affinity with an active pocket of receptors showing strong hydrogen bond interactions. The compounds C5 and C2 showed potent antioxidant activity. In addition, the drug-likeness of the hybrids was assessed by predicting their physicochemical, pharmacokinetic (ADME), toxicity profiles, and photophysical properties.

Bifunctional Lewis Base Catalyzed Asymmetric N-Allylic Alkylation of 2-Hydroxypyridines.

A chiral Lewis base catalyzed enantioselective N-allylic alkylation of 2-hydroxypyridines and MBH carbonates is documented, affording a convenient access to N-alkylated 2-pyridones with up to 99% ee and 99% yield. Experimental and computational studies have revealed that the strong hydrogen bond interaction between the chiral Lewis base catalyst and 2-hydroxypyridines plays a crucial role in this reaction for the reactivity, chemoselectivity, and enantioselectivity.

Universal Ligands for Dispersion of Two-Dimensional MXene in Organic Solvents.

Ligands can control the surface chemistry, physicochemical properties, processing, and applications of nanomaterials. MXenes are the fastest growing family of two-dimensional (2D) nanomaterials, showing promise for energy, electronic, and environmental applications. However, complex oxidation states, surface terminal groups, and interaction with the environment have hindered the development of organic ligands suitable for MXenes. Here, we demonstrate a simple, fast, scalable, and universally applicable ligand chemistry for MXenes using alkylated 3,4-dihydroxy-l-phenylalanine (ADOPA). Due to the strong hydrogen-bonding and π-electron interactions between the catechol head and surface terminal groups of MXenes and the presence of a hydrophobic fluorinated alkyl tail compatible with organic solvents, the ADOPA ligands functionalize MXene surfaces under mild reaction conditions without sacrificing their properties. Stable colloidal solutions and highly concentrated liquid crystals of various MXenes, including Ti2CTx, Nb2CTx, V2CTx, Mo2CTx, Ti3C2Tx, Ti3CNTx, Mo2TiC2Tx, Mo2Ti2C3Tx, and Ti4N3Tx, have been produced in various organic solvents. Such products offer excellent electrical conductivity, improved oxidation stability, and excellent processability, enabling applications in flexible electrodes and electromagnetic interference shielding.

Weak Noncovalent Interactions in Three Closely Related Adamantane-Linked 1,2,4-Triazole N-Mannich Bases: Insights from Energy Frameworks, Hirshfeld Surface Analysis, In Silico 11β-HSD1 Molecular Docking and ADMET Prediction.

Structural analysis and docking studies of three adamantane-linked 1,2,4-triazole N-Mannich bases (1-3) are presented. Compounds 1, 2 and 3 crystallized in the monoclinic P21/c, P21 and P21/n space groups, respectively. Crystal packing of 1 was stabilized by intermolecular C-H⋯O interactions, whereas compounds 2 and 3 were stabilized through intermolecular C-H⋯N, C-H⋯S and C-H⋯π interactions. The energy frameworks for crystal structures of 1-3 were described. The substituent effect on the intermolecular interactions and their contributions were described on the basis of Hirshfeld surface analyses. The 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) inhibition potential, pharmacokinetic and toxicity profiles of compounds 1-3 were determined using in silico techniques. Molecular docking of the compounds into the 11β-HSD1 active site showed comparable binding affinity scores (-7.50 to -8.92 kcal/mol) to the 11β-HSD1 co-crystallized ligand 4YQ (-8.48 kcal/mol, 11β-HSD1 IC50 = 9.9 nM). The compounds interacted with key active site residues, namely Ser170 and Tyr183, via strong hydrogen bond interactions. The predicted pharmacokinetic and toxicity profiles of the compounds were assessed, and were found to exhibit excellent ADMET potential.

Comprehensive in silico screening of flavonoids against SARS-CoV-2 main protease

In the current pandemic caused by the new coronavirus (SARS-CoV-2), computational drug discovery can play an essential role in finding potential therapeutic agents. Thanks to its anti-viral, antibacterial, and anti-inflammatory properties, sage (Salvia officinalis) is used in traditional medicine. In this study, drugs proposed against COVID-19, including Lopinavir, Remdesivir, Favipiravir, and main flavonoids of sage, were docked favorably against novel coronavirus main protease. Molecular docking findings indicate that Rutin, Luteolin-7-glucoside, Apigenin, and Hispidulin make strong interactions with better binding affinity than selected commercial drugs in the study. But Rutin is the only flavonoid that makes strong hydrogen bond interactions with catalytic dyad and crucial Mpro residues and has more binding affinity than protease inhibitor PF-07321332 as an oral antiviral (PAXLOVID™). Further analysis of Molecular Dynamics and MM-PBSA predicted that chosen ligands could form stable complexes with the main protease. Also, ADMET analysis shows that main flavonoids are expected to have appropriate pharmacokinetic and no toxic properties. The results of the in silico study suggest that Salvia officinalis as a rich source of potent anti-coronavirus flavonoids may play a significant role in counteracting the replication of SARS-CoV-2. Communicated by Ramaswamy H. Sarma

Bio-inspired polybenzoxazine coating: Anti-corrosion and anti-abrasion performance enhancement through monomer design

Polybenzoxazine (PBZ) is a kind of high corrosion-resistant polymer, however, the brittleness and weak adhesion strength of PBZ have puzzled their applications. In this work, we introduced ether amine molecules into benzoxazine monomers via molecule design, and then copolymerized them with tannic acid (TA) to realize flexible PB-TA coating systems, aiming at achieving durable corrosion and abrasion protection for steel structures. It is found that the PB-TA copolymer gains favorable plasticity up to 39.44 % elongation. Meanwhile, TA provides more active sites and stronger hydrogen bond interaction, which increases the crosslinking density of PB-TA coating and achieves a high adhesion strength (13.57 MPa) to the mild steel substrate. Further experiments evidence that the PB-6TA coating (with 6 % mass of TA addition in the PBZ) presents high corrosion resistance (>109 Ω.cm2 after 600 h salt spraying test), far beyond polyurethane and epoxy resin coatings. Also, the PB-6TA coating exhibits a higher anti-friction ability during cyclic wear corrosion test than the pristine PBZ coating. It is expected that this work may help boost the development of polybenzoxazine-based coatings with long-term corrosion resistance in harsh marine environments.

Insights into the rheological properties, multi-scale structure and in vitro digestibility changes of starch-β-glucan complex prepared by ball milling

High amylose corn starch (HACS)-oat β-glucan (OBG) complex was prepared by ball milling treatment. The morphology and structure of the samples were characterized, and the digestibility of the samples was studied. SEM analysis showed that the grain structure of oat β-glucan-starch after ball milling showed an irregular aggregate shape. The rheological results indicated that the apparent viscosity of the solution of HACS-OBG complex prepared by ball milling, with the values of both G′ and G″ decreasing on the increase of OBG addition. Multi-scale structure analysis showed that the disorder of the crystal structure and short-range structure of the HACS-OBG complex would lead to the decrease of the double helix structure content. In terms of digestibility, the RDS of the complex decreased from 75.88 % to 66.26 %, which suppressed the digestibility of starch. Molecular docking and quantum chemistry techniques further demonstrated the strong hydrogen bond interaction between HACS and OBG and the inhibition rate of OBG on the enzyme, which was conducive to the slow digestion of HACS-OBG complex. Therefore, ball milling treatment can promote the binding of OBG to starch, which may be an effective method for postprandial blood glucose control.