Partial Least-Squares Study of the Effects of Organic Modifier and Physicochemical Properties on the Retention of Some Thiazoles

JPC – Journal of Planar Chromatography – Modern TLC - Reversed-phase (RP) HPTLC with aqueous ammonia-organic modifier (acetonitrile, dioxane, acetone) mobile phases has been used to...     

Electrochemical synthesis, characterization and some properties of a polymer derived from thioflavin S

Polymeric films derived from thioflavin S were electrosynthesized on mild steel and silver electrodes in sulfuric acid and lithium perchlorate-containing aqueous solutions. The introduction of thioflavin S in an acidic solution protected the surface of steel from corrosion. The electrochemical behavior of the steel coated with a layer of poly(thioflavin) was examined by electrochemical impedance spectroscopy. The films exhibited a capacitive behavior and were semi-conductive in nature. Infra red reflectance measurements of the polymer films at the steel surface showed that the polymer structure retained the aromatic structure of the benzene and thiazole rings with the distinction of a nitrogen quinone vibrational band. Surface morphology of the polymer film was examined with scanning electron microscopy. The films are yellow, compact and dense when electrochemically formed onto steel surfaces when compared to a blue rather porous when formed onto silver electrode. The mechanism of electropolymerization of thioflavin is given and found similar to that of aniline with the possibility of metal chelation with the sulfur and/or nitrogen in the thiazole ring.     

Determination of diamine oxidase by a kinetic method with 2,2''-azino-di(3-ethylbenzthiazoline-6-sulfonate)

Hydrogen peroxide, the product of diamine oxidase-catalyzed putrescine or cadaverine oxidation, formed in proportion to the enzyme activity, is measured spectrophotometrically by using the above sulfonate (ABTS) and peroxidase. Only one reagent solution containing 3 mmol of putrescine or 10 mmol of cadaverine, 4 mmol of ABTS and 3000 U of peroxidase per litre of 0.2 mol l^-1 Tris—0.1 mol l^-1 HCl buffer pH 7.5 is needed. Absorbance changes are measured at 410 nm over the first 3 min of the reaction. This initial oxidation rate of the chromogen enables diamine oxidase activity up to 230 U l^-1 to be determined.     

Thermal analysis and kinetics of the copper-lead matte roasting process

In this paper, the results of copper-lead matte investigations are presented. Investigated copper-lead matte is intermediate product of the lead production in TREPCA-Zvečan. In the first part of the paper characterization of starting material is presented, consisting of: chemical composition analysis (XRQ), scanning electron microscopy (SEM) and diffractometry (XRD). Thermal properties of investigated matte were determined using differential thermal analysis (DTA) at characteristic temperatures. Using results of induced analysis, mechanism of matte oxidation process was determined. In the second part of the paper kinetic parameters describing oxidative roasting of copper-lead matte are presented. For activation energy calculations, non-isothermal methods defined by Kissinger and Ozawa were used [1, 2]. Kinetic equation describing oxidation process was determined using Sharps method of reduced half time of reaction [3].     

Spectrophotometric determination of ethanol by an enzymatic method with 2, 2'-azino-di(3-ethylbenzthiazo- line-6-sulfonate)

The method is based on the oxidation of ethanol in the presence of alcohol oxidase, followed by oxidation of 2,2'-azino-di(3-ethylbenzthiazoline-6-sulfonate) in the presence of peroxidase.     

Reversal of Regioselectivity of Nitrone Cycloadditions by Lewis Acids

The regio‐ and stereoselectivity of cycloadditions of the nitrone 1a and the chiral, sugar‐derived nitrones 13a and 13b with 3‐(prop‐2‐enoyl)‐1,3‐oxazolidin‐2‐one ( 2 ) depends on the nature of the Lewis acid catalyst used. Addition of Lewis acid reverses the regioselectivity of the cycloaddition, and improves the anti‐diastereoselectivity in the case of chiral nitrones. The sterically favored isoxazolidin‐5‐yl‐substituted adducts 3, 4 , and 14 – 17 are produced as the major products in the absence of Lewis acid, while the electronically favored regioisomers with isoxazolidin‐4‐yl substituents ( 5, 6 , and 18 – 21 , respectively) are obtained as major products in the [Ti(OⁱPr)₂Cl₂] catalyzed reactions. The reactions of nitrone 13b with 2 in the presence of other Lewis acids such as ZnCl₂, ZnBr₂, ZnI₂ and MgI₂/I₂ gave both regioisomeric pairs of the diastereoisomers, favoring the 4‐substituted congeners. The diastereoisomeric isoxazolidines 3a – 6a were reduced with NaBH₄ in THF/H₂O with subsequent desilylation to yield the separable diols 9 – 12 . Reduction of the diastereoisomeric isoxazolidines 19a and 18a afforded the chiral alcohols 23 and 22 , the latter of which was analyzed by X‐ray crystallography.     

The separation of some Bi- and tervalent cations on zirconium phosphate columns

Summary On small columns filled with the inorganic cation-exchanger zirconium phosphate, Zn²⁺-Cd²⁺ were quantitatively and Ni²⁺-Co²⁺ partly separated. The exchanger was in the NH₄+ form, and 0.5–4N NH₄Cl served as eluent. With the exchanger in the H+ form, U0₂ ²⁺ was separated from bivalent cations and ferric iron by stepwise elution with 0.1, 0.5 and 4N HCl solutions.

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Zusammenfassung An kleinen Säulen des anorganischen Kationenaustauschers Zirkoniumphosphat wurden Zn²⁺ und Cd²⁺ quantitativ, Ni²⁺ und Co²⁺ teilweise getrennt. Der Austauscher lag in der NH₄+-Form vor, 0,5-bis 4-n Ammoniumchlorid diente als Eluent. Mit der H+-Form des Austauschers wurde UO₂ ²⁺ von zweiwertigen Kationen und von Fe³⁺ durch schrittweise Elution mit 0,1-, 0,5- und 4-n Salzsäure getrennt.

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Résumé On a séparé Zn²⁺-Cd²⁺ quantitativement et Ni²⁺-Co²⁺ partiellement sur de petites colonnes remplies de phosphate de zirconium comme échangeur minéral cationique. L'échangeur se trouvait sous forme NH₄+ et l'on a pris NH₄Cl 0,5-4N comme éluant. Avec l'échangeur sous forme H⁺, on a séparé UO₂ ²⁺ des cations bivalents et de l'ion ferrique par élution graduelle avec des solutions chlorhydriques 0,1, 0,5 et 4N.

     

Herbal Arsenal against Skin Ailments: A Review Supported by In Silico Molecular Docking Studies

Maintaining healthy skin is important for a healthy body. At present, skin diseases are numerous, representing a major health problem affecting all ages from neonates to the elderly worldwide. Many people may develop diseases that affect the skin, including cancer, herpes, and cellulitis. Long-term conventional treatment creates complicated disorders in vital organs of the body. It also imposes socioeconomic burdens on patients. Natural treatment is cheap and claimed to be safe. The use of plants is as old as mankind. Many medicinal plants and their parts are frequently used to treat these diseases, and they are also suitable raw materials for the production of new synthetic agents. A review of some plant families, viz., Fabaceae, Asteraceae, Lamiaceae, etc., used in the treatment of skin diseases is provided with their most common compounds and in silico studies that summarize the recent data that have been collected in this area.     

Limoniastrum monopetalum–Mediated Nanoparticles and Biomedicines: In Silico Study and Molecular Prediction of Biomolecules

An in silico approach applying computer-simulated models helps enhance biomedicines by sightseeing the pharmacology of potential therapeutics. Currently, an in silico study combined with in vitro assays investigated the antimicrobial ability of Limoniastrum monopetalum and silver nanoparticles (AgNPs) fabricated by its aid. AgNPs mediated by L. monopetalum were characterized using FTIR, TEM, SEM, and DLS. L. monopetalum metabolites were detected by QTOF–LCMS and assessed using an in silico study for pharmacological properties. The antibacterial ability of an L. monopetalum extract and AgNPs was investigated. PASS Online predictions and the swissADME web server were used for antibacterial activity and potential molecular target metabolites, respectively. Spherical AgNPs with a 68.79 nm average size diameter were obtained. Twelve biomolecules (ferulic acid, trihydroxy-octadecenoic acid, catechin, pinoresinol, gallic acid, myricetin, 6-hydroxyluteolin, 6,7-dihydroxy-5-methoxy 7-O-β-d-glucopyranoside, methyl gallate, isorhamnetin, chlorogenic acid, 2-(3,4-dihydroxyphenyl)-5,7-dihydroxy-4-oxo-4H-chromen-3-yl 6-O-(6-deoxy-β-l-mannopyranosyl)-β-d-glucopyranoside) were identified. The L. monopetalum extract and AgNPs displayed antibacterial effects. The computational study suggested that L. Monopetalum metabolites could hold promising antibacterial activity with minimal toxicity and an acceptable pharmaceutical profile. The in silico approach indicated that metabolites 8 and 12 have the highest antibacterial activity, and swissADME web server results suggested the CA II enzyme as a potential molecular target for both metabolites. Novel therapeutic agents could be discovered using in silico molecular target prediction combined with in vitro studies. Among L. Monopetalum metabolites, metabolite 12 could serve as a starting point for potential antibacterial treatment for several human bacterial infections.