Ionic liquid-supported chiral saldach with tunable hydrogen bonding: synthesis,metalation with Fe(III) and in vitro antimicrobial susceptibility

New water-soluble methylimidazolium ionic liquids (MIILs) bearing N,N′-bis-(salicylidene)-R,R-1,2-diaminocyclohexane (saldach) scaffold, H₂(R¹)₂saldach(2-MeIm⁺X⁻)₂ (4a: R¹=H, X=Cl^–; 4b: R¹=H, X=PF₆^–; 4c: R¹=H, X=BF₄^–; 4d: R¹=ⁱPr, X=Cl^–; 4e: R¹=ⁱPr, X=PF₆^–; 4f: R¹=ⁱPr, X=BF₄^–), and their Fe(III) complexes have been synthesized and structurally characterized as well as their profile of antimicrobial susceptibility was identified. The new saldach-supported MIILs demonstrated a distinctly enhanced biocidal effect toward methicillin resistant Staphylococcus aureus (MRSA) and multidrug-resistant Escherichia coli (MDREC). Compound 4d is the most potent antibacterial agent and could inhibit the growth of all micro-organisms, except A. flavus, more effectively than standard antibiotics.     

Synthesis and antibacterial activity of some novel thieno[2,3-c]pyridazines using 3-amino-5-phenyl-2-ethoxycarbonylthieno[2,3-c]pyridazine as a starting material

3-Amino-5-phenyl-2-ethoxycarbonylthieno[2,3-c]pyridazine (6) was prepared by reaction of 4-cyano-6-phenylpyridazine-3(2H)-thione (4) with ethyl chloroacetate in the presence of sodium ethoxide. Hydrazinolysis of compound 6 yielded the corresponding carbohydrazide, (9) which on treatment with acetylacetone and ethyl acetoacetate produced the novel thieno[2,3-c]pyridazines (10 and 11). Treatment of compound 9 with nitrous acid yielded the corresponding carboazide (13), which upon boiling in toluene furnished imidazo[4′,5′:4,5]thieno[2,3-c]pyridazine (15). Pyrimidothienopyridazines (16–18) were achieved by cyclocondensation of compound 9 with some reagents, namely acetic anhydride, formic acid, and triethyl orthoformate. The newly synthesized compounds were confirmed by elemental analyses and spectral data. The antibacterial activities of the new compounds were also evaluated.     

The development of platinum-rhodium alloy coatings on SS304 using a pulse/direct electrodeposition technique and their application to antibacterial activity

The current research focused on the development of Platinum–Rhodium alloy coating (Pt– Rh) on SS304 and its applications in antibacterial studies. Electrodeposition is considered to be one of the most suitable methods because it enhances the therapeutic effects of noble metals (Pt–Rh alloy). The electrodeposited coating is an economical and time-saving alternative to existing coating methods. The newly developed Pt–Rh coating was investigated using a scanning electron microscope (SEM) and an atomic force microscope (AFM). Using the agar Petri plate and broth culture method, the antibacterial effect of the platinum-rhodium alloy was investigated against Gram-negative Escherichia coli and Gram-positive bacteria such as Staphylococcus saprophytes, Bacillus Subtilis, and Enterococcus faecalis. The Pt–Rh alloy coated samples obtained by Direct current (DC) and Pulse coating (PC 50% and PC 75%) were examined for antibacterial study. The PC 75% Pt–Rh alloy coating exhibits significant antibacterial activity, demonstrating a maximum zone of inhibition while leaving the rest of the coated samples by DC and PC 50% duty cycles. The study also found that when the concentration of Pt–Rh solution rises from 5 μL to 15 μL, so does the antibacterial activity. The findings of the study showed that electrodeposited platinum-rhodium alloy metal ions may be handy bacteriostatic in the coming years.     

Synthesis,characterization and antioxidant,antibacterial activity Zn2+, Cu2+, Ni2+ and Co2+, complexes of ligand [2-(thiophen-2-yl)-1-(thiophen-2-ylmethyl)-1H-benzo[d]imidazole]

New metal complexes of (Zn(II), Co(II), Ni(II) and Cu(II)) based on the ligand 2-(thiophen-2-yl)-1-(thiophen-2-ylmethyl)-1H-benzo[d]imidazole] were synthesized, whose structures were determined with the different spectroscopic techniques ¹H NMR,¹³C NMR, FT-IR, UV–Visible and by mass spectrometry. The thermal analysis was performed by TG-DTA. The antioxidant activity of the ligand and its complexes was evaluated by DPPH (2,2-diphenyl-1-picrylhydrazyl) method, in comparison with the synthetic antioxidant, ascorbic acid. The results obtained showed that the antioxidant activity of the ligand and its complexes is moderate and that the copper complex has a high activity that exceeds that of ascorbic acid. Antimicrobial activity of the ligand and its metal complexes was studied against two Gram-positive bacteria: Bacillus subtilis ILP1428B, Staphylococcus aureus CIP543154 and two Gram-negative bacteria: Pseudomonas aeruginosa ATCC27653, Escherichia coli CIP5412 (American Type Culture Collection)the activity data show that the metal complexes are more potent than the free ligand.     

Comparative evaluation of antibacterial potentials of nano cobalt oxide with standard antimicrobials

Development of suitable potent antimicrobial is the urgent need of modern era to cope up the problem of antimicrobial resistance. The applications of nanotechnology in metal oxides have shown favorable effects to some extent in this area. Thus, the present study was investigated to evaluate the antibacterial properties of cobalt oxide (Co₃O₄) nanoparticles at different concentrations and their comparison with standard antimicrobials i.e. tetracycline and gentamicin. Nanoparticles were synthesized and characterized by standard techniques. The antibacterial potentials of Co₃O₄ nanoparticles against S. aureus and E. coli were determined at various concentrations. The maximum zone of inhibitions of Co₃O₄ nanoparticles against S. aureus and E. coli at 500 μg/ml were 21.17 mm and 24.00 mm, respectively. The Co₃O₄ nanoparticles seemed more effective than gentamicin against S. aureus and E. coli. The nanoparticles with respect to tetracycline showed higher than 1 activity index at ≥ 125 μg/ml for E. coli and ≥31.25 μg/ml for S. aureus. It was also higher than 1 at all compared concentrations with respect to gentamicin against both bacteria. In conclusion, Co₃O₄ nanoparticles seemed to have potent antibacterial potential and these might be very helpful to replace the conventional antimicrobials to solve the problem of antibacterial resistance.     

Synthesis and Antibacterial Activity of Selenium-functionalized Poly(ε-caprolactone)

A selenium-functionalizedε-caprolactone was synthesized by introducing a phenyl selenide group at the 7-position.A polymer was obtained through the ring-opening polymerization of this monomer in a base/thiourea binary organocatalytic system.A living polymerization process was achieved under mild conditions.The resulting polymers had a controlled molecular weight with a narrow molecular weight distributions and high end-group fidelity.Random copolymers could be obtained by copolymerizing this monomer withε-caprolactone.The thermal degradation temperature of the obtained copolymers decreased with the increasing molar ratio of selenide functionalized monomer in copolymers,while the glass transition temperature increased.In addition,the phenyl selenide side group could be further modified to a polyselenonium salt,which resulted in a polymer with good antibacterial properties.The survival rate of E.coli and S.aureus was only 9%with a polymer concentration of 62.5μg/mL.     

Ruellia prostrata Poir. activity evaluated by phytoconstituents,antioxidant, anti-inflammatory,antibacterial activity,and in silico molecular functions

Ruellia prostrata Poir. has been used historically as an anti-cancer, wound healing agent and to treat gonorrhea. We aimed to determine the phytochemicals present in ethyl acetate extract of R. prostrata Poir. (EAERP). We sought to determine the antioxidant, anti-inflammatory, and antibacterial activities in vitro, and toxicity properties in vivo. We also analyzed the Prediction of Activity Spectra for Substances (PASS), physicochemical, ADMET, and drug-likeness properties of phytochemicals in EAERP. To determine phytoconstituents, preliminary phytochemical screening and GC–MS were performed, while FT-IR was used to identify functional groups. The antioxidant activity was evaluated using a DPPH scavenging assay, whereas BSA denaturation and RBC hemolysis inhibition were used to assess anti-inflammatory activity. An agar-well-diffusion assay was performed to estimate the antibacterial activity. Brine shrimp lethality bioassay and oral delivery of EAERP of single-dose were performed to determine cytotoxicity and acute toxicity, respectively. The phytochemical screening revealed the presence of phenols, triterpenoids, saponins, steroids, amino acids, and fat and fixed oils. FT-IR analysis of EAERP showed the presence of many functional groups: alcohols/phenols, carboxylic acids, aldehydes, alkanes, esters, amines, amides, aromatic hydrocarbons, sulfoxides, and alkyl halides. GC–MS revealed the presence of 39 phytoconstituents including steroids, consistent with compounds and functional groups found in preliminary screening and FT-IR. EAERP showed dose-dependent antioxidant activity with an IC₅₀ value of 21.402 µg/mL and anti-inflammatory activity with an IC₅₀ value of 20.564 µg/mL in RBC hemolysis inhibition and 21.115 µg/mL in BSA denaturation assays. EAERP also exhibited dose-related antibacterial activity. EAERP exerted cytotoxicity with an LC₅₀ value of 17.619 μg/mL and acute toxicity with an LD₅₀ value of 4095.328 mg/kg without any adverse effects. The PASS server also predicted that the phytoconstituents of EAERP have antioxidant, anti-inflammatory, and antibacterial activities with probable activity (Pa) ranging from 0.310 to 0.717. Analysis of physicochemical, ADMET, and drug-likeness properties revealed the drug-able efficacy and safety of most compounds. The findings of this study indicated that R. prostrata Poir. contains phytoconstituents with potent antioxidant, anti-inflammatory, and antibacterial activities. Taken together, our measurements suggest that R. prostrata Poir. is a prime candidate for further exploration as a potential therapeutic agent.     

Influence of the particle size on the antibacterial activity of green synthesized zinc oxide nanoparticles using Dysphania ambrosioides extract,supported by molecular docking analysis

Bacteria-associated infections have increased in recent years due to treatment resistance developed by these microorganisms. Due to the high antibacterial capacity associated with their nanometric size, nanoparticles, such as zinc oxide (ZnO), have proven to be an alternative for general medical procedures. One of the methodologies to synthesize them is green synthesis, where the most commonly used resources are plant species. Using Dysphania ambrosioides extract at various synthesis temperatures (200, 400, 600, and 800 °C), zinc oxide nanoparticles (ZnO-NPs) with average sizes ranging from 7 to 130 nm, quasi-spherical shapes, and hexagonal prism shapes were synthesized. Larger sizes were obtained by increasing the synthesis temperature. The ZnO crystalline phase was confirmed by X-ray diffraction and transmission electron microscopy. The sizes and shapes were observed by field emission scanning electron microscopy. The Zn-O bond vibration was identified by Fourier transform infrared spectroscopy. Thermogravimetry showed the stability of ZnO-NPs. The antibacterial evaluations, disk diffusion test, and minimum bactericidal concentration, demonstrated the influence of particle size. The smaller the nanoparticle size, the higher the inhibition for all pathogenic strains: Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, and dental pathogens: Streptococcus mutans, Streptococcus sanguinis, Porphyromonas gingivalis, and Prevotella intermedia. The molecular docking study showed a favorable interaction between ZnO-NPs and some proteins in Gram-positive and Gram-negative bacteria, such as TagF in Staphylococcus epidermidis and AcrAB-TolC in Escherichia coli, which led to proposing them as possible targets of nanoparticles.     

Jute stick extract assisted hydrothermal synthesis of zinc oxide nanoflakes and their enhanced photocatalytic and antibacterial efficacy

In this paper, we used green and hydrothermal methodology to prepare zinc oxide (ZnO) nanoflakes (NFs) with jute stick extract (J–ZnO NFs) as growth substrate. The prepared materials were characterized using different analytical techniques including ultraviolet–visible spectroscopy (UV–vis), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The characteristic absorption peak for ZnO NFs and J–ZnO NFs were observed from the UV–vis spectrum at 373 and 368 nm respectively. The hexagonal wurtzite crystal structure of ZnO NFs and J–ZnO NFs was confirmed by XRD analysis. FESEM and TEM analyses of synthesized J–ZnO NFs confirmed their NFs shape and collectively flower-like structure formation by the assembly of NFs of J–ZnO on cellulose of jute stick extract substrate. The FTIR analysis revealed the functional groups of jute stick extract biomolecules, mainly cellulose, are responsible for the formation of collectivel flower like J–ZnO NFs structure. The XPS analysis revealed the surface and chemical compositions (Zn, C, and O) of J–ZnO NFs. The photocatalytic performance of ZnO NFs and J–ZnO NFs samples was carried out by the degradation of methylene blue (MB) dye solution under UV light irradiation. The degradation efficiency of ZnO NFs and J–ZnO NFs was obtained 79 % and 89 %, respectively, for 5 h. Notably, the degradation efficiency of the J–ZnO NFs was 98 % after 8 h of irradiation, which is very inspiring. The both NFs exhibited first-order kinetics with MB photodegradation. We also examined the possible antibacterial activity of both samples against Escherichia coli (E. coli) pathogens, which demonstrated a significant result with a 17 mm and 19 mm zone of inhibition by ZnO NFs and J–ZnO NFs respectively.