Synthesis and Anti-Chikungunya Virus (CHIKV) Activity of Novel 1,4-Naphthoquinone Sulfonamide and Sulfonate Ester Derivatives

Chikungunya virus (CHIKV) is a re-emerging disease caused by an alphavirus of the Togaviridae family. Since its first description in 1952, the disease has spread worldwide, affecting populations in both tropical and temperate countries. To date, there is no licensed vaccine or specific pharmacological treatment. Therefore, there is an increasing urgency in developing new antiviral drugs capable of specifically inhibiting viral replication. In the present work, we report the synthesis and antiviral activity evaluation of nineteen naphthoquinone derivatives, containing a sulfonamide or sulfonate group. Cell viability assays indicated a low toxic potential for all tested compounds and inhibitory assays against CHIKV identified five compounds with potent activity. The compounds were also evaluated for their virucidal potential, and the results demonstrated that compound 11a exhibited a virucidal effect higher than 70% in the treatment with 20 µM. Furthermore, in silico studies were performed to predict the antiviral drug targets.

Organic-Sulfonate Functionalized Graphene as a High Temperature Lubricant for Efficient Antifriction and Antiwear in Water-Based Drilling Fluid

The lubricity of drilling fluid resistant to high-temperature over 200℃ is still one of the technological breakthroughs. In this study, the graphene modified with sodium dodecylbenzene sulfonate (SDBS) was selected as a resistant to high-temperature lubricant. Our results show that the drilling fluids have high stability after aging at 240°C with the assistance of the SDBS/graphene. Excitingly, the tribological performance test results revealed that the SDBS/graphene exert excellent anti-friction and anti-wear properties. Compared with the base slurry, the friction coefficient and wear rate of the SDBS/graphene slurry are reduced by 76% and 59%, respectively. The deposited film composed of graphene, Al2O3, SiO2, Fe2O3, FeSO4 actualized the protection of the sliding contact zone, proving that the sulfonate group on the SDBS/graphene contributed to prompt the deposition of the graphene and bentonite and then enhanced tribological properties of the drilling fluids. Overall, the graphene modified with SDBS is expected to solve the difficulty to form effective deposited film and poor lubricity of the drilling fluid under high-temperature.

Coarse-grained molecular models of the surface of hair

We present a coarse-grained molecular model of the surface of human hair, which consists of a lipid monolayer, in the MARTINI framework. Using molecular dynamics simulations, we identify a lipid grafting distance that yields a monolayer thickness consistent with atomistic simulations and experimental measurements of hair surfaces. Coarse-grained models for fully-functionalised, partially damaged, and fully damaged hair surfaces are created by randomly replacing neutral thioesters with anionic sulfonate groups. This mimics the progressive removal of fatty acids from the hair surface by bleaching. We study the structure of the lipid monolayer at different degrees of damage using molecular dynamics simulations in vacuum as well as in polar (water) and non-polar (n-hexadecane) solvents. We also compare the wetting behaviour of water and n-hexadecane on the hair surfaces through contact angle measurements conducted using molecular dynamics simulations and experiments. Our model captures the experimentally-observed transition of the hair surface from hydrophobic (and oleophilic) to hydrophilic (and oleophobic) as the level of bleaching damage increases. By using surfaces with different damage ratios, we obtain contact angles from the simulations that are in good agreement with experiments for both solvents on virgin and bleached human hairs. In both the molecular dynamics simulations and further experiments using biomimetic surfaces, the cosine of the water contact angle increases linearly with the sulfonate group surface coverage. We expect that the proposed systems will be useful for future molecular dynamics simulations of the adsorption and tribological behaviour of hair surfaces.

Sulfation modification of dopamine in brain regulates aggregative behavior of animals

Behavioral plasticity and the underlying neuronal plasticity represent a fundamental capacity of animals to cope with environmental stimuli. Behavioral plasticity is controlled by complex molecular networks that act under different layers of regulation. While various molecules have been found to be involved in the regulation of plastic behaviors across species, less is known about how organisms orchestrate the activity of these molecules as part of a coherent behavioral response to varying environments. Here we discover a mechanism for the regulation of animal behavioral plasticity involving molecular sulfation in brain, a modification of substrate molecules by sulfotransferase (ST)-catalyzed addition of a sulfonate group (SO3) from an obligate donor, 3’-phosphoadenosine 5’-phosphosulfate (PAPS) to the substrates. We investigated aggregation behaviors of the migratory locusts, which are well-known for extreme phase change plasticity triggered by population density. The processes of PAPS biosynthesis acted efficiently on induction of locust behavioral transition: Inhibition of PAPS synthesis solicited a behavioral shift from gregarious to solitarious states; external PAPS dosage, by contrast, promoted aggregation in solitarious locusts. Genetic or pharmacological intervention in the sulfation catalyzation resulted into pronounced solitarizing effects. Analysis of substrate-specific STs suggests a widespread involvement of sulfated neurotransmitters in the behavioral response. Dopamine in brain was finally identified to be actively sulfate conjugated, and the sulfate conjugation enhanced the free DA-mediated behavioral aggregation. Similar results in Caenorhabditis elegans and mouse indicate that sulfation may be involved more broadly in the modulation of animal aggregation. These findings revealed a general mechanism that effectively regulates animal social-like behavioral plasticity possibly through sulfation-mediated modification of neural networks.

Tuning the Mechanical and Thermal Properties of Hydroxypropyl Methylcellulose Cryogels with the Aid of Surfactants

The mechanical and thermal properties of cryogels depend on their microstructure. In this study, the microstructure of hydroxypropyl methylcellulose (HPMC) cryogels was modified by the addition of ionic (bis (2-ethylhexyl) sodium sulfosuccinate, AOT) and non-ionic (Kolliphor® EL) surfactants to the precursor hydrogels (30 g/L). The surfactant concentrations varied from 0.2 mmol/L to 3.0 mmol/L. All of the hydrogels presented viscous behavior (G″ > G′). Hydrogels containing AOT (c > 2.0 mmol/L) led to cryogels with the lowest compressive modulus (13 ± 1 kPa), the highest specific surface area (2.31 m2/g), the lowest thermal conductivity (0.030 W/(m·°C)), and less hygroscopic walls. The addition of Kolliphor® EL to the hydrogels yielded the stiffest cryogels (320 ± 32 kPa) with the lowest specific surface area (1.11 m2/g) and the highest thermal conductivity (0.055 W/(m·°C)). Density functional theory (DFT) calculations indicated an interaction energy of −31.8 kcal/mol due to the interaction between the AOT sulfonate group and the HPMC hydroxyl group and the hydrogen bond between the AOT carbonyl group and the HPMC hydroxyl group. The interaction energy between the HPMC hydroxyl group and the Kolliphor®EL hydroxyl group was calculated as −7.91 kcal/mol. A model was proposed to describe the effects of AOT or Kolliphor®EL on the microstructures and the mechanical/thermal properties of HPMC cryogels.

The Effect of Reaction Time and Temperature on the Synthesis of Methyl Ester Sulfonate Surfactant from Palm Oil as a Feedstock using Microwave-Assisted Heating

Methyl ester sulfonate is an anionic surfactant that can be synthesized from palm oil as a raw material with the addition of sodium bisulfite and calcium oxide catalyst through transesterification and sulfonation process using microwave-assisted heating. The effect of microwave-assisted heating in the transesterification-sulfonation process was investigated in this study. The transesterification process was carried out using a microwave power of 300 watts for 10 minutes with an addition of a KOH catalyst of 1%. The transesterification process gave a result of palm oil methyl ester with a yield of up to 98% and density of 0.8546 gr/ml, and kinematic viscosity of 3.19 cSt. The sulfonation process is carried out using palm oil methyl ester and sodium bisulfite with a mole ratio of 1:3 and calcium oxide catalyst of 1.5% with the microwave power of 300 watts while varying the sulfonation time and temperature. The physicochemical properties of methyl ester sulfonate were analyzed, and the sulfonate group was characterized using FTIR. The optimum condition gave a yield of up to 98.68%, the density of 0.8657 gr/ml, viscosity of 3.75 cSt, pH of 2.12, and surface tension of up to 27.34 dyne/cm at a temperature of 100oC and sulfonation time of 40 minutes.

Crystal structure of palbociclib isethionate Form B, (C24H30N7O2)(C2H5O4S)

The crystal structure of palbociclib isethionate has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional theory techniques. Palbociclib isethionate crystallizes in space group P-1 (#2) with a = 8.71334(4), b = 9.32119(6), c = 17.73725(18) Å, α = 80.0260(5), β = 82.3579(3), γ = 76.1561(1)°, V = 1371.282(4) Å3, and Z = 2. The crystal structure is dominated by cation⋯anion and cation⋯cation hydrogen bonds, which result in layers roughly parallel to the (104) plane. Both hydrogen atoms on the protonated nitrogen atom of the pyrimidine ring participate in strong hydrogen bonds to the anions. One proton binds to the sulfonate group, while the other bonds to the hydroxyl group of the isethionate anion. The hydroxyl group of the anion acts as a donor to a ketone oxygen atom in the cation. There are also strong N–H⋯N hydrogen bonds, which occur in pairs linking the cations into dimers with rings having a graph set R2,2(8). The powder pattern has been submitted to ICDD® for inclusion in the Powder Diffraction File™.

Anion Exchange Membrane Based on Sulfonated Poly (Styrene-ethylene-butylene-styrene) Copolymers

Sulfonated poly(styrene-ethylene-butylene-styrene) copolymer (S-SEBS) was prepared as an anion exchange membrane using the casting method. The prepared S-SEBS was further modified with sulfonic acid groups and grafted with maleic anhydride (MA) to improve the ionic conducting properties. The prepared MA-grafted S-SEBS (S-SEBS-g-MA) membranes were characterized by Fourier transform infrared red (FT-IR) spectroscopy and dynamic modulus analysis (DMA). The morphology of the S-SEBS and S-SEBS-g-MA was investigated using atomic force microscopy (AFM) analysis. The modified membranes formed ionic channels by means of association with the sulfonate group and carboxyl group in the SEBS. The electrochemical properties of the modified SEBS membranes, such as water uptake capability, impedance spectroscopy, ionic conductivity, and ionic exchange capacity (IEC), were also measured. The electrochemical analysis revealed that the S-SEBS-g-MA anion exchange membrane showed ionic conductivity of 0.25 S/cm at 100% relative humidity, with 72.5% water uptake capacity. Interestingly, we did not observe any changes in their mechanical and chemical properties, which revealed the robustness of the modified SEBS membrane.

Microwave Enhanced Synthesis of Sulfonated Chitosan-montmorillonite for Effective Removal of Methylene Blue

In this work, sulfonated chitosan montmorillonite composite (S-CS-MT) beads were synthesized using a microwave irradiation method designed to have a better saving-time procedure. The potency of S-CS-MT as an adsorbent was assessed for the removal of cationic dyes such as methylene blue (MB) from aqueous solution. The batch adsorption experiments indicated that MB adsorption onto S-CS-MT follows the Pseudo-second-order kinetic and Langmuir isotherm model. The maximum extent obtained from the Langmuir isotherm model for MB adsorption was 188.2 mg g− 1 at 303 K. The thermodynamic study indicated that the adsorption reaction is favorable and spontaneous. These findings indicated that montmorillonite chitosan grafted with the sulfonate group has the ability and efficacy as biohybrid adsorbent for the adsorption of cationic dyes.