Starch nanoparticles as a bio-nanocatalyst in synthesis of diheteroaryl thioethers

Nanostarch is shown to be a highly efficient, eco-friendly and heterogenous organocatalyst for the synthesis of the diheteroaryl thioethers via one-pot reaction of methylcarbonyls, thiourea and iodine in DMSO. This method offers significant advantages such as available starting materials, higher purity and excellent yield of products, very easy reaction conditions and absence of any tedious purification. Furthermore, because of employing eco-friendly catalyst without using transition metal catalysts, this novel method emerges as a green-approach leading to less harmful residues. Moreover, a mechanism was proposed to rationalize the reaction and the role of starch nanoparticles was also investigated in these transformations.     

Spectrophotometric determination of acidity constants by two-rank annihilation factor analysis

Annihilation of the contribution of one chemical component from the original data matrix is a general method in rank annihilation factor analysis (RAFA). However, RAFA is not applicable for studying the protonation equilibria of multiprotic acids. In this work, a two-rank annihilation factor analysis (TRAFA) method was proposed for determination of the acidity constants of diprotic acids. After recording the electronic absorbance spectra of the acids at different pH, the contributions of both H₂A and A²⁻ were annihilated from the absorbance data, which made feasible the determination of two successive acidity constants. The method was validated by analysis of simulated data and its application to the determination of the acidity constants of calmagite, as a reference compound. A close agreement was obtained between the resulted values by TRAFA and the declared values. Indeed, the method was used for determination of the acidity constants of two new chromenone derivatives in binary solvents mixtures of methanol and water. The effects of changing solvent composition on acidity constant data were explained by linear solvation free energy relationships (LSFER) utilizing solvatochromic parameters.     

Silica supported perchloric acid (HClO4-SiO2): an efficient reagent for the preparation of primary carbamates under solvent-free conditions

The synthesis of primary carbamates from structurally diverse compounds containing a hydroxyl group has been performed in high yields and purity, and without any epimerization under solvent-free conditions using HClO₄-SiO₂ as a mild, convenient, and effective reagent. The procedure is operationally simple, efficient, and environmentally benign.     

Green synthesis and chemical characterization of copper nanoparticles using Allium saralicum leaves and assessment of their cytotoxicity,antioxidant, antimicrobial,and cutaneous wound healing properties

In recent decades, nanotechnology is growing rapidly owing to its widespread application in science and industry. The aim of the experiment was the green synthesis of copper nanoparticles using Allium saralicum R.M. Fritsch aqueous extract and assessment of their cytotoxicity, antioxidant, antibacterial, antifungal, and cutaneous wound healing effects under in vitro and in vivo conditions. These nanoparticles were characterized by Fourier transformed infrared spectroscopy (FT‐IR), UV–visible spectroscopy, field emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). DPPH free radical scavenging test was done to assess the antioxidant properties, which indicated similar antioxidant potentials for CuNPs@Allium and butylated hydroxytoluene. Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), and Minimum Fungicidal Concentration (MFC) were specified by macro‐broth dilution assay. CuNPs@Allium indicated higher antibacterial and antifungal effects than all standard antibiotics (p ≤ 0.01). Also, CuNPs@Allium inhibited the growth of all bacteria at 1–8 mg/ml concentrations and removed them at 2–8 mg/ml concentrations (p ≤ 0.01). In the case of antifungal properties of CuNPs@Allium, they prevented the growth of all fungi at 1–4 mg/ml concentrations and destroyed them at 2–8 mg/ml concentrations (p ≤ 0.01). In vivo experiment, after creating the cutaneous wound, the rats were randomly divided into six groups (n = 10): untreated control, treatment with Eucerin basal ointment, treatment with 3% tetracycline ointment, treatment with 0.2% CuSO₄ ointment, treatment with 0.2% A. saralicum ointment, and treatment with 0.2% CuNPs@Allium ointment. Use of CuNPs@Allium ointment in the treatment groups substantially reduced (p ≤ 0.01) the wound area, total cells, neutrophil, macrophage, and lymphocyte and remarkably raised (p ≤ 0.01) the wound contracture, hydroxyl proline, hexosamine, hexuronic acid, fibrocyte, and fibrocytes/fibroblast rate compared to other groups. The synthesized CuNPs@Allium had high cell viability dose‐dependently (Investigating the effect of the plant on HUVEC cell line) and revealed this method was nontoxic. The results revealed the useful non‐cytotoxic, antioxidant, antibacterial, antifungal, and cutaneous wound healing effects of CuNPs@Allium.     

l-Arginine as a base and ligand for the palladium-catalyzed C-C and C-N cross-coupling reactions in aqueous media

l-Arginine (2-amino-5-guanidinopentanoic acid) acts as a base and ligand in reaction medium, exhibits a very high activity and recyclability to palladium-catalyzed C-C and C-N cross-coupling reactions in aqueous media. The corresponding Suzuki products were obtained in good to excellent yields by using various aryl halides (I, Br, Cl). Also, the cross coupling reactions of arylboronic acids with various amines in aqueous medium proceed in good to excellent yield under same conditions. Furthermore, the catalyst could be easily separated from the reaction mixture and could be recycled several times without significant loss in its catalytic activity.     

Partial least squares-based multivariate spectral calibration method for simultaneous determination of beta-carboline derivatives in Peganum harmala seed extracts

The partial least squares regression method has been applied for simultaneous spectrophotometric determination of harmine, harmane, harmalol and harmaline in Peganum harmala L. (Zygophyllaceae) seeds. The effect of pH was optimized employing multivariate definition of selectivity and sensitivity and best results were obtained in basic media (pH > 9). The calibration models were optimized for number of latent variables by the cross-validation procedure. Determinations were made over the concentration range of 0.15-10 μg mL⁻¹. The proposed method was validated by applying it to the analysis of the β-carbolines in synthetic quaternary mixtures of media at pH 9 and 11. The relative standard errors of prediction were less than 4% in most cases. Analysis of P. harmala seeds by the proposed models for contents of the β-carboline derivatives resulted in 1.84%, 0.16%, 0.25% and 3.90% for harmine, harmane, harmaline and harmalol, respectively. The results were validated against an existing HPLC method and it no significant differences were observed between the results of two methods.