Preparation, Antibacterial Activity, and Catalytic Application of Magnetic Graphene Oxide-Fucoidan in the Synthesis of 1,4-Dihydropyridines and Polyhydroquinolines

CuFe2O4@SiO2@L-arginine@Cu(I) as a new magnetically retrievable heterogeneous nanocatalyst with high efficiency for 1,4-disubstituted 1,2,3-triazoles synthesis

A novel magnetic heterogeneous catalyst was synthesized through the immobilization of copper ions onto the l-arginine functionalized CuFe₂O₄@SiO₂. The prepared catalyst was characterized by Fourier Transform Infrared (FT-IR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), and Energy Dispersive X-Ray spectroscopy (EDX). The resulting catalyst was used in the ultrasonic-assisted synthesis of 1,2,3-triazoles via a one-pot three-component reaction of alkynes, alkyl halides, and sodium azides under green conditions within a short time. The catalyst reusability was investigated after five cycles and no significant loss of activity was observed.

Design and development of novel magnetic Lentinan/PVA nanocomposite for removal of diazinon, malathion, and diclofenac contaminants

Increasing population growth and rapid expansion of the industrialization of the world society have caused severe environmental pollution to the planet. This study was carried out in order to investigate the synthesis of biopolymeric texture nano adsorbent based on the Lentinan (LENT), Poly Vinyl Alcohol (PVA) and Iron Oxide nanoparticles for the removal of environmental pollutants. The spherical structural morphology of Fe₃O₄@LENT/PVA nanocomposite has been determined by FE-SEM analyses. According to the obtained results from FTIR analyses, all absorption bands of the Fe₃O₄, LENT, and PVA, had been existed in nanocomposite and approved the successful formation of it. From EDS analysis, it has been revealed that 57.21 wt% Fe, 17.56 wt% C and 25.23 wt% O. Also, the XRD pattern of the nanocomposite, approved the presence of polymeric and magnetic parts with card no. JCPDS, 01-075-0033. The BET analysis has defined specific surface area (47 m²/g) and total pore volume (0.15 cm³/g). Moreover, high heterogeneity and structural stability of the fabricated Fe₃O₄@LENT/PVA nanocomposite have been proven by TGA. Besides, VSM analysis measured great magnetic property of the nanocomposite (48 emu/g). Also, the Fe₃O₄@LENT/PVA nanocomposite potential for effective removal of malathion (MA), Diazinon (DA), and Diclofenac (DF) from watery solution has studied by an experiment based on the efficacy of adsorbent dosage, pH, and temperature. The adsorption kinetics of three pollutants had investigated using pseudo-first-order (PFO), pseudo-second-order (PSO) and intra-particle diffusion (IPD) velocity equations, the results showed that the kinetics followed PSO velocity equations. Also, the Langmuir, Freundlich, Dubbin-Radushkevich (D-R) and Temkin isotherm models had investigated, and the adsorption isotherm was adopted from the Langmuir model. The results demonstrated that in the presence of Fe₃O₄@LENT/PVA nanocomposite, at the optimal conditions (contact time = 180 min, pH = 5, nanocomposite dosage = 0.20 g/L and temperature of 298 K) the maximum adsorption capacity of MA, DF, and DA were 101.57, 153.28, and 102.75 mg/g, respectively. The antibacterial features of the Fe₃O₄@LENT/PVA nanocomposite, had evaluated by Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria, but the result did not show any antibacterial activity.

1,4-Dihydropyridine as a Promising Scaffold for Novel Antimicrobials Against Helicobacter pylori

The increasing occurrence of multidrug-resistant strains of the gastric carcinogenic bacterium Helicobacter pylori threatens the efficacy of current eradication therapies. In a previous work, we found that several 1,4-dihydropyridine (DHP)-based antihypertensive drugs exhibited strong bactericidal activities against H. pylori by targeting the essential response regulator HsrA. To further evaluate the potential of 1,4-DHP as a scaffold for novel antimicrobials against H. pylori, we determined the antibacterial effects of 12 novel DHP derivatives that have previously failed to effectively block L- and T-type calcium channels. Six of these molecules exhibited potent antimicrobial activities (MIC ≤ 8 mg/L) against three different antibiotic-resistant strains of H. pylori, while at least one compound resulted as effective as metronidazole. Such antimicrobial actions appeared to be specific against Epsilonproteobacteria, since no deleterious effects were appreciated on Escherichia coli and Staphylococcus epidermidis. The new bactericidal DHP derivatives targeted the H. pylori regulator HsrA and inhibited its DNA binding activity according to both in vitro and in vivo analyses. Molecular docking predicted a potential druggable binding pocket in HsrA, which could open the door to structure-based design of novel anti-H. pylori drugs.