Asian Journal of Green Chemistry
Volume:4 Issue: 1, Winter 2020

Lactoperoxidase (LPO) enzyme inhibition by tautomeric propylthiouracil (PTU) structures have been investigated in this work based on the in silico methodologies. Six possible PTU structures have been optimized to obtain their energy-minimized structures based on quantum mechanics computations. Afterwards, their interactions with LPO enzyme have been evaluated based on molecular docking simulations. The results indicated that the structural changes of PTU analogues could perturbate the interaction properties, in which it could be seen by either the magnitudes of binding energies or the types of interacting amino acids. In this work, the original thio-keto structure of PTU showed better interaction properties with LPO enzyme; however, the properties for other PTU derivatives have been deviated from this reference model. It is known that the tautomerism is common for biological structures; therefore, exploring their arisen effects on the structural properties and activities could reveal insightful information for judging their potency and efficacy.

In this work, TiO2-graphene/chitosan nanocomposite with high photocatalytic activity was successfully synthesized and characterized by various analyses such as XRD, TEM, SEM, EDX and DRS. The photocatalytic activity was tested vs. removal of methyl red as ananionic dye under black light radiation. Based on the results, TiO2-graphene/chitosan nanocomposite could effectively remove methyl red, and demonstrate an excellent photocatalytic enhancement over TiO2 and TiO2-graphene samples. The degradation reaction fit well to a Langmuir-Hinshelwood kinetic model implying that the reaction rate is depended on the initial adsorption step. An artificial neural network (ANN) comprising four input variables (TiO2-graphene/chitosan dosage, initial dye concentration, reaction time and temperature of the solution), eight neurons and an output variable (Removal efficiency %) was optimized, tested and validated for methyl red degradation by the prepared TiO2-graphene/chitosan nanocomposite. The results showed that the predicted data from the designed ANN model are in good agreement with the experimental data with a correlation coefficient (R2) of 0.9831. Based on the results, reaction time is the most influential variable and the temperature of solution is the less influential parameter in the removal efficiency of methyl red.

This study concerns the removal of acid blue-15 (AB-15) from water using chitosan through the batch sorption. To get the best percentage of removal, several experimental parameters have been used such as the initial concentration, temperature, and pH. The results show that the pH of the interaction medium does not indicate a significant influence in the adsorption process. In addition, the percentage of removal increased with the increase of dosage of chitosan and temperature of the reaction vessel. Furthermore, the percentage of removal decreases with the increase in the initial concentration of the AB-15 solution. The adsorption of AB-15 on the chitosan fits better with the Freundlich (R2= 0.998) than the Langmuir model. The adsorption kinetics follows the pseudo-first order (R2> 0.998) but not the pseudo-second-order model. The obtained results of this study show that chitosan has a potential application as a membrane to remove the AB-15 from industrial effluents.

In this study, we synthesized Ag supported on hydroxyapatite-core-shell-γ-Fe2O3 nanoparticles (γ-Fe2O3@HAp-Ag NPs) as a new, lewis acid, and reusable heterogeneous nancatalyst. Then, it was successfully used for the synthesis of β-azido alcohols and β-thiocyanohydrins from the regioselective conversation of some epoxides by azide and thiocyanate anions in water. The reaction afforded the corresponding products with high regioselectivity under mild reaction conditions.

The reverse water gas shift reaction over the prepared tungsten carbide alloy (WC/AC) from date palm fronds catalyst was studied by CO2 hydrogenation, temperature-programmed reduction of the WC/AC catalyst. In comparison to the reaction of CO2 alone, hydrogen can significantly promote the CO formation in the RWGS reaction. The formate derived from association of H2 and CO2 is proposed to be the key intermediate for CO production. Formate dissociation mechanism is the major reaction route for CO production. The reverse water gas shift (RWGS) reaction over WC/AC with potassium (K) promoter was studied by means of CO2 hydrogenation at temperature programmed. The main role of Potassium oxide (K2O) was to provide catalytic activity for decomposition of formats, besides acting as a promoter for CO2 adsorption. Hydrogen was dissociatively adsorbed on WC/AC and could spill over to K2O to associate with CO2. This resulted in the formation of formate species for the production of CO.

Polyethylene glycol-bis (N-methylimidazolium) dihydroxide, [PEG(mim)2][OH]2, was prepared from the reaction of polyethylene glycol-bis (N-methylimidazolium) dibromide and sodium hydroxide in aqueous media at ambient temperature. The obtained solid was used as a novel, green, recyclable and efficient basic phase-transfer catalyst in the synthesis of 2-amino-3-cyano-4H-pyrans via the one-pot three-component condensation reaction of aromatic aldehydes, malononitrile and 1,3-dicarbonyl compounds in water at room temperature. The reactions without any basic reactants and in the presence of trace amounts of the catalyst gave the corresponding products with high yields in short reaction times. The phase-transfer catalyst could be successfully reused without the significant decrease in its activity.

In this research article, we report the synthesis of imidazo[1,2-a]pyridine derivatives through Ugi condensation in the presence of saccharin as an organocatalyst used in a three component reaction. The convenient synthetic protocol, short reaction times, easy work up, good to excellent yields and mild reaction conditions make this process both practical and attractive.

The aim of this study is to investigate the effectiveness of isora fibre mixed with 1% calcium carbonate (CaCO3) as reinforcement for polypropylene (PP) thermoplastic matrix. Isora fibers were subjected to mercerization prior to blending with PP in order to obtain good interfacial adhesion with the matrix.  A  PP/isora composite has been prepared by melt blending of PP with 5%, 10%, 15%, 20% alkali treated Isora fibre in co-rotating twin screw extruder. The extruded strands are pelletized and then injection moulded to obtain specimens. The optimum compositions of the PP/alkali treated isora composites were mixed with 1% CaCO3. Fibre-matrix adhesion will be analysed by mechanical and thermal properties of the composites were evaluated.

In this research work, TiO2-SiO2/alginate nanocomposite with high surface area has been prepared and applied as adsorbent for the removal of azo dye methyl orange from aqueous solutions. Characteristics of phases and crystallite size of TiO2-SiO2/alginate nanocomposite were obtained from XRD and the surface area and pore size distribution were achieved from BET and BJH analysis methods. TiO2-SiO2/alginate nanocomposite with pure anatase phase, the average crystallite size of 8.3 nm, has specific surface area of 188.4 m2/g–1. To find the nature of adsorption procedure, the equilibrium adsorption isotherms were investigated. The linear correlation coefficients of Langmuir, Freundlich and Temkin isotherms were obtained. Based on results, Langmuir isotherm model fitted the experimental data better than the other models. According to the Langmuir isotherm model, the maximum adsorption capacity of TiO2-SiO2/alginate nanocomposite for sequestering methyl orange was about 68.85 mg/ . Furthermore, negative ΔG0 and ΔH0 values obtained through thermodynamic investigation indicated that the adsorption of methyl orange onto TiO2-SiO2/alginate nanocomposite was simultaneous and exothermic in nature, respectively.

Antioxidant activity is strongly influenced by the amount of total phenolics, natural habitat and the specific growing conditions (climate, soil minerals, humidity external contaminants), flowering period and other factors. A number of degenerative diseases i.e. cancer, autoimmune diseases, rheumatoid arthritis, cardiovascular etc. are due to oxidative stress. The human body has several mechanisms to counteract oxidative stress, by producing natural antioxidants or by submitting them to the outside through food and/or supplements. Once the antioxidant enters the body, it does not necessarily pass unchanged through the gastro-intestinal tract. It must therefore be considered bioavailability and bioactivity. The bioavailability of phenolic and polyphenolic compounds was studied in detail over the past two decades, whether by examining the kinetic models of polyphenol absorption in body fluids of healthy free radicals or by enhancing the immune system and reducing the risk of cancer and degenerative diseases. In recent years, there has been an increased interest in finding natural antioxidants because they can interfere with the distribution of reactions of free radicals. The most effective components are phenolic compounds contained in many vegetable raw materials.