Enhancing the Decolorization of Methylene Blue Using a Low-Cost Super-Absorbent Aided by Response Surface Methodology

The presence of organic dyes from industrial wastewater can cause pollution and exacerbate environmental problems; therefore, in the present work, activated carbon was synthesized from locally available oil palm trunk (OPT) biomass as a low-cost adsorbent to remove synthetic dye from aqueous media. The physical properties of the synthesized oil palm trunk activated carbon (OPTAC) were analyzed by SEM, FTIR-ATR, and XRD. The concurrent effects of the process variables (adsorbent dosage (g), methylene blue (MB) concentration (mg/L), and contact time (h)) on the MB removal percentage from aqueous solution were studied using a three-factor three-level Box–Behnken design (BBD) of response surface methodology (RSM), followed by the optimization of MB adsorption using OPTAC as the adsorbent. Based on the results of the analysis of variance (ANOVA) for the three parameters considered, adsorbent dosage (X₁) is the most crucial parameter, with an F-value of 1857.43, followed by MB concentration (X₂) and contact time (X₃) with the F-values of 95.60 and 29.48, respectively. Furthermore, the highest MB removal efficiency of 97.9% was achieved at the optimum X₁, X₂, and X₃ of 1.5 g, 200 mg/L, and 2 h, respectively.     

Chemistry of bicyclic [1,3,4]thiadiazole 5-5 systems containing ring-junction nitrogen

This review provides a survey of the advances in the methods of formation and chemical reactivity of bicyclic [1,3,4]thiadiazole 5-5 systems containing ring-junction nitrogen over the period from 1989 to the beginning of 2017.     

Tin-Naphthalene Sulfonic Acid Complexes as Photostabilizers for Poly(vinyl chloride)

Poly(vinyl chloride) degrades when exposed to ultraviolet light for long durations; therefore, the photostability of polymeric materials should be enhanced through the application of additives. New organotin complexes containing 4-aminonaphthalene-1-sulfonic acid were synthesized and their role as poly(vinyl chloride) photostabilizers were evaluated. The reaction of 4-amino-3-hydroxynaphthalene-1-sulfonic acid and appropriate di- or trisubstituted tin chloride (triphenyltin chloride, tributyltin chloride, dibutyltin dichloride, and dimethyltin dichloride) in methanol under reflux gave the corresponding tin-naphthalene complexes with yields of 75%–95%. Elemental analyses and spectroscopic techniques including infrared and nuclear magnetic resonance (proton and tin) were used to confirm their structures. The tin complexes were added to poly(vinyl chloride) to produce thin films that irradiated with ultraviolet light. Various parameters were assessed, such as the weight loss, formation of specific functional groups, changes in the surface due to photoirradiation, and rate constant of photodegradation, to test the role played by the organotin complexes to reduce photodegradation in polymeric films. The results proved that organotin complexes acted as photostabilizers in these circumstances. The weight loss, formation of fragments containing specific functional groups, and undesirable changes in the surface of polymeric films were limited in the presence of organotin complexes. Organotin complexes containing three phenyl groups showed the most desirable stabilization effect. These act as efficient primary and secondary photostabilizers, and as decomposers for peroxides. In addition, such an additive inhibits the dehydrochlorination process, which is the main cause of poly(vinyl chloride) photodegradation.     

Solvent effect on the folding dynamics and structure of E6-associated protein characterized from ab initio protein folding simulations

Solvent effect on protein conformation and folding mechanism of E6-associated protein (E6ap) peptide are investigated using a recently developed charge update scheme termed as adaptive hydrogen bond-specific charge (AHBC). On the basis of the close agreement between the calculated helix contents from AHBC simulations and experimental results, we observed based on the presented simulations that the two ends of the peptide may simultaneously take part in the formation of the helical structure at the early stage of folding and finally merge to form a helix with lowest backbone RMSD of about 0.9 A? in 40% 2,2,2-trifluoroethanol solution. However, in pure water, the folding may start at the center of the peptide sequence instead of at the two opposite ends. The analysis of the free energy landscape indicates that the solvent may determine the folding clusters of E6ap, which subsequently leads to the different final folded structure. The current study demonstrates new insight to the role of solvent in the determination of protein structure and folding dynamics.     

Synthesis and biological evaluation of 99mTc-ECF: a new ethionamide derivative for tuberculosis diagnosis

In this work we propose a technetium-99m-labeled derivative from Ethionamide (ETH), further referred to as ^99mTc-ECF for tuberculosis diagnosis. The biological features of this radioactive agent have been studied. The 2-ethylpyridine-4-carbothioamide-ferrocène (ECF) was chemically synthesized and then labeled with technetium-99m. It has been confirmed through this work that ^99mTc-ECF is obtained with high radiolabelling yield (>90 %). Radiochemical analysis of ^99mTc-ECF revealed that the molecule was efficiently labeled with a little free remaining pertechnetate. Only 1–2 % of the tracer was leached out from the complex at 24 h when incubated in serum at 37 °C which confirmed its high stability. The sensitivity test of ECF showed that the group of grafted ferrocenyl does not seem to have largely altered the active site of the molecule. In-vitro investigations were conducted using BCG (Bacille Calmette-Guérin) as analogue of Mycobacterium Tuberculosis and Listeria Monocytogenes as negative control. It was proved that for BCG, ECF has kept the bacteriostatic properties of the parent compound (ETH). In physiological conditions, the measured up-take of the tracer with live bacteria was about 24.1 and 7.1 % for BCG and Listeria Monocytogenese, respectively. The comparison of the ^99mTc-ECF accumulation at sites of BCG infected animals, which is expressed as target-to-non-target ratio (found to be equal to 2.15) with other radiotracers was discussed. This allowed us to consider that ^99mTc-ECF could be a reasonable radiotracer for mycobacterial infections. Obtained results were good and encourage to undergo a similar labeling for the Mycobacterium tuberculosis as perspective of this work.     

Understanding the basis of I50V‐induced affinity decrease in HIV‐1 protease via molecular dynamics simulations using polarized force field

Human immunodeficiency virus (HIV)‐1 protease is one of the most promising drug target commonly utilized to combat Acquired Immune Deficiency Syndrome (AIDS). However, with the emergence of drug resistance arising from mutations, the efficiency of protease inhibitors (PIs) as a viable treatment for AIDS has been greatly reduced. I50V mutation as one of the most significant mutations occurring in HIV‐1 protease will be investigated in this study. Molecular dynamics (MD) simulation was utilized to examine the effect of I50V mutation on the binding of two PIs namely indinavir and amprenavir to HIV‐1 protease. Prior to the simulations conducted, the electron density distributions of the PI and each residue in HIV‐1 protease are derived by combining quantum fragmentation approach molecular fractionation with conjugate caps and Poisson–Boltzmann solvation model based on polarized protein‐specific charge scheme. The atomic charges of the binding complex are subsequently fitted using delta restrained electrostatic potential (delta‐RESP) method to overcome the poor charge determination of buried atom. This way, both intraprotease polarization and the polarization between protease and the PI are incorporated into partial atomic charges. Through this study, the mutation‐induced affinity variations were calculated and significant agreement between experiments and MD simulations conducted was observed for both HIV‐1 protease‐drug complexes. In addition, the mechanism governing the decrease in the binding affinity of PI in the presence of I50V mutation was also explored to provide insights pertaining to the design of the next generation of anti‐HIV drugs. © 2015 Wiley Periodicals, Inc.     

A Simple and Convenient Synthesis of 4‐Ylidene‐5(4H)oxazolone Derivatives: Oxazolone Ring Transformation Leading to Other Heterocyclic Structures

Simple, effective, and high yield synthetic procedure for the synthesis of 4‐ylidene‐5(4H)‐oxazolones 2a–m from arylidene‐malononitriles under solvent‐free conditions is described. The scope of this reaction was investigated, and it was found that the presence of anhydrous sodium acetate gave the corresponding oxazolones in excellent yields. The newly generated oxazolone derivative 2m underwent ring transformation into pyrroles, imidazoles, pyridazine, and triazines.     

Parasitological and Biochemical Efficacy of the Active Ingredients of Allium sativum and Curcuma longa in Schistosoma mansoni Infected Mice

The active ingredients allicin and curcumin have a wide range of actions against fungi, bacteria, and helminths. Therefore, the study was aimed to evaluate the efficacy of allicin (AL) and curcumin (CU) as antischistosomal drugs and their biochemical effects in normal and Schistosoma mansoni-infected mice. Praziquantel (PZQ) was administrated for two successive days while AL or CU was given for two weeks from the week 7th postinfection (PI). The possible effect of different regimens on Schistosoma worms was evaluated by measuring the percentage of the recovered worms, tissue egg load, and oogram pattern. Serum alanine transaminase activity and levels of triglycerides, cholesterol, and uric acid were measured. Liver tissue malondialdehyde and reduced glutathione levels besides, the activities of glutathione-S-transferase, superoxide dismutase and catalase were assessed for the oxidative/antioxidant condition. DNA electrophoresis of liver tissue was used to indicate the degree of fragmentation. There was a significant reduction in the recovered worms and egg load, with a marked change of oogram pattern in all treated groups with PZQ, AL, and CU in comparison with infected-untreated mice. PZQ, AL, and CU prevented most of the hematological and biochemical disorders, as well as significantly improved the antioxidant capacity and enhanced DNA fragmentation in the liver tissue of schistosomiasis mice compared to the infected-untreated group. These promising results suggest that AL and CU are efficient as antischistosomal drugs, and it would be beneficial to test their combination to understand the mechanism of action and the proper period of treatment leading to the best result.     

Conversion of 3-Carbethoxy-4-methyl Coumarin Derivatives into Several New Annelated Coumarin Derivatives

The reaction of ethyl esters of 4-methyl-2-oxo-2H-l-benzo(naphtho) pyran.3-carboxylic acids (1) with aromatic aldehy-des in the presence of piperidine yielded 4-styryl-3-carboxami-dopiperidyl connmrin derivatives 4. The reaction of hydrazlne hydrate with 1 gave acetophenone hydrozone derivatives 5 and acetophenone azine derivatives 6. The reaction of 1 with prima-ry amines afforded compomlds 7—9. And the treatment of la with Grignard reagents afforded 3-aroyl-4-methyl coumarin derivatives 10.