Hydroxyethyl curdlan as a novel water soluble derivative: Synthesis,characterization, and antioxidant capacity

In this study, hydroxyethyl curdlans (HeCDs) with different molecular weights were successfully fabricated. The structure and properties of the synthesized HeCDs were measured by FTIR, ¹³C nuclear magnetic resonance (NMR), and Raman spectroscopy and compared with curdlan. The degree of crystallinity of HeCDs was measured with X-ray diffractometry (XRD). Differential scanning calorimetry and thermogravimetric analysis were performed to determine thermal properties of HeCs. Solubility of HeCDs was tested in water, common organic solvents, and NaOH solution. Antioxidant activities of HeCs were investigated using various in vitro assay systems. The HeCDs exhibited a dose-dependent free radical scavenging activity as shown by their DPPH radical, ABTS radical and superoxide anion radical inhibition, and ferrous chelating ability and reducing power. The improved water solubility property and antioxidant activity of these curdlan derivatives could have a wide range of applications, particularly its use as an antioxidant in food, food packaging, biomedical, and pharmaceutical industries.     

Synthesis,characterization and antibacterial studies of some new tellurated azo compounds

A series of tellurated azo compounds [i.e. (4-HOC₆H₄N=N-Ar)TeBr₃ and (4-HOC₆H₄N=N-Ar)₂TeBr₂, where Ar=5-BrC₆H₃, 5-CH₃C₆H₃ and 5-NO₂C₆H₃] were prepared by the reaction of the corresponding 2-(4-hydroxyphenylazo)aryl mercury chloride with tellurium tetrabromide in 1:1 and 2:1?mole ratio, respectively in dry dioxane as a solvent. The reduction of (4-HOC₆H₄N=N-Ar)TeBr₃ by hydrazine hydrate gave the corresponding ditelluride (i.e., (4-HOC₆H₄N=N-Ar)₂Te₂). Treatment of (4-HOC₆H₄N=N-Ar)₂TeBr₂ with hydrazine hydrate afforded the corresponding tellurides, (4-HOC₆H₄N=N-Ar)₂Te), in good yields. The structures of all newly synthesized compounds were assigned on the basis of their elemental and spectroscopic data. The antibacterial activity of tellurated azo compounds along with mercurated azo compounds was tested with agar diffusion method against the bacteria strains Staphylococcus aureus and Escherichia coli. The antibacterial activities of tellurated azo compounds were in some cases equal or better than those of the reference drug. The mercurated azo compounds were found to be the more antibacterial activity of than those of tellurated azo compounds.     

Preparation,characterization of some transition metal complexes of hydrazone derivatives and their antibacterial and antioxidant activities

A new series of metal complexes of Pd(II), Cd(II) and Cu(II, I) of polydentate Schiff base ligand (H₂L), namely ((Z)-2-(phenylamino)-N'-(thiophen-2-ylmethylene) acetohydrazide) have been prepared. The ligand and its metal complexes have been characterized based on various physicochemical studies as elemental analyses, molar conductance, spectral (UV–Vis, MS, IR, ¹H NMR, ¹³C NMR and XRD), magnetic moment measurements and thermal studies (TG, DTG). In the view of previous studies, the ligand (H₂L) acts as polydentate one and coordinates with metal ions to form all metal complexes. The kinetic and thermodynamic parameters of decomposition process (ΔG, ΔH, ΔS) were calculated. The possible structures of the metal complexes have been computed using the molecular mechanic calculations using the hyper chem. 8.03 molecular modeling program. The calculations are performed to obtain the optimized molecular geometry. The antibacterial study of the selected compounds was assayed against two pathogenic bacteria. Moreover, the complexes (Cu II, I), Cd(II), Pd(II)) and the ligand revealed excellent antioxidant properties and could be useful in fighting the free radicals which occur in close connection with cancerous cells. It was remarkable that the two complexes (Cu II, I) demonstrated stronger antioxidant effects than their parent compounds. It is clear that the new complexes are good active compounds for use in a variety of applications.     

Synthesis,characterization, thermal stability and antibacterial activity of coumarin based methacrylate copolymers

Monomer of 7-methacryloyloxy-4-methylcoumarin(MAOMC) was synthesized and characterized by FTIR, 1H-NMR and 13C-NMR spectroscopy. Copolymers of MAOMC with butoxyethylmethacrylate(BOEMA) at different feed compositions were prepared by free radical solution polymerization at(70 ± 1) °C in ethylmethylketone(EMK) using benzyl peroxide(BPO) as an initiator. The copolymers were characterized by FTIR and 1H-NMR spectroscopy. Thermogravimetric analysis(TGA) and differential scanning calorimetry(DSC) of the copolymers showed moderate thermal stability and higher Tg values. Gel permeation chromatography(GPC) was used to find out the molecular weights of the different copolymers. Antibacterial activities of the copolymers were also investigated against the selected pathogenic bacteria's. The antibacterial activity of the copolymer increases as the MAOMC content increases in the copolymer. This shows that coumarin moiety plays a very important role in the antibacterial activity.     

Synthesis,spectral characterization,thermal, computational and antibacterial studies of lanthanide complexes with 2-fluorobenzoic acid-(5-R-2-hydroxy-benzylidene)hydrazide {R = chloro or bromo)

Tridentate Schiff base ligands, 2-Fluorobenzoic acid-(5-chloro-2-hydroxy benzylidene)hydrazide {H₂L_Cl} and 2-Fluorobenzoic acid-(5-bromo-2-hydroxybenzylidene)hydrazide {H₂L_Br} have been used to prepare a variety of lanthanide complexes [HNEt₃][LnL_x(NO₃)₂(H₂O)]H₂O, Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Er. The ¹H and ¹³C NMR of lanthanum in conjunction with the infrared, elemental, thermal, molecular mass and conductance measurements enable the assignment of the formula to these complexes. The anionic unit [LnL_x(NO₃)₂(H₂O)]^? contains one tridentate ONO-donor, L^2?, which coordinates the metal ions via the phenolate-O, the imine-N and the deprotonated amide-O atoms in enol tautomeric form. The coordination environment around central metal ion is completed by two bidentate nitrate ligands and one coordinated water molecule to give a coordination number of eight for Ln(III). In order to get a better insight into the structural features of the complexes, their molecular geometries were fully optimized using density functional theory calculations at the M06-2X/6-31G¹ level of theory. The antibacterial activity results, on a panel of six different bacterial strains, show that the activity of the complexes is higher than that of the free ligands and in some cases higher than that of amoxicillin which is taken as standard reference drug. Compared to the free ligands, the emission spectra of the complexes exhibit a blue-shift with a clear enhancement in the emission intensity.     

NiO nanoparticle doped-PVA-MF polymer nanocomposites: Preparation,Congo red dye adsorption and antibacterial activity

The standard of living has been improved by industrial “revolution” and the demand of new production increases due to population explosion. In the race of industrialization humans are busy discharging harmful gases in atmosphere, dumping unhealthy wastes in soil and discharging of toxic sewage in natural water resources. The present work reports the synthesis of polymer nanocomposite of blend encapsulated with NiO nanoparticles (K1-K5). The polymer nanocomposite films (K1-K5) were characterized by FTIR, XRD, TGA and SEM. The electrostatic interaction between the polymer matrix and encapsulated NiO nanoparticles increases the chemical stability in this order water > NaOH > HCl solution confirmed by contact angle (55° to 99°). The Congo red (CR) dye adsorption values increases in polymer nanocomposite films (K1-K5) were analyzed by an effect by an effect of contact time 45% to 68%, by an effect of CR dye concentration 48% to 70%. But the CR dye adsorption by S3 composite and nanocomposite films (K1-K5) are inversely proportional to the pH scale 4–10. Among four different bacterial strains Bacillus subtilis 25 mm and Staphylococcus aureus 25 mm has shown best antibacterial activity. The result confirms enhancement of antibacterial activity of S3 blend after the doping of NiO nanoparticles. The present results may be a roadmap to develop some transparent and flexible polymer nanocomposite films for water treatment in textile industries and efficient antibacterial activity.     

Synthesis,characterization, and antioxidant activity of a new Gd(III) complex

A new gadolinium(III) complex of 5-aminoorotic acid (HAOA) was synthesized by reaction of the respective inorganic salt in molar ratio of 1:3 to ligand. The structure of the complex was determined by elemental analysis, FT-IR, and FT-Raman spectroscopies. Significant differences in the IR and Raman spectra of the complex were observed as compared to the spectra of the free ligand. Detailed vibrational analysis of HAOA and Gd(III)-AOA systems revealed that the binding mode in the complex was bidentate through the carboxylic oxygens. The newly synthesized gadolinium(III) complex of 5-aminoorotic acid (GdAOA) showed antioxidant properties. The antioxidant activity of both HAOA and GdAOA was related with their electron donor properties.     

Synthesis,characterization, thermal,antimicrobial and antioxidant studies of some transition metal dithiocarbamates

Metal dithiocarbamate complexes of Co(II) [1], Cu(II) [2], Mn(II) [3], Cr(III) [4], and Pd(II) [5] have been synthesized using sodium N-ethyl-N-phenyldithiocarbamate (NaL). The complexes were characterized by elemental analyses, FTIR and UV–vis spectroscopic techniques, magnetic moment, molar conductance and thermal analyses (TGA and DSC). The infrared spectra indicated the coordination of dithiocarbamate through the two sulphur atoms in a symmetrical bidentate fashion. The thermal behavior of these complexes showed that the hydrated complexes lost water molecules in the first step, followed by decomposition of the ligand molecules in the final steps. Mass loss considerations at these final decomposition steps indicate conversion of the complexes to sulphides. The antimicrobial potentials of the complexes were evaluated against some selected bacteria strains (Escherichia coli, Pseudomonas aureginosa, Salmonella typhi and Staphylococcus aureus) and fungi organisms (Aspergillus flavus and Fasiparium oxysporium). The compounds showed a broad spectrum of fungicidal and bactericidal activities which exceeds that of the control drugs at a 100 μg/mL concentration. The antioxidant properties of the ligand and its Cu(II) complex were evaluated in vitro using DPPH assay, and the complex was found to exhibit better radical scavenging ability than the free ligand.     

Synthesis,characterization, and antioxidant activities of three Cu(II) complexes with Schiff-base ligands

Cu(II) complexes of three bis(pyrrol-2-yl-methyleneamine) ligands were synthesized and characterized by elemental analyses, mass spectra, and IR spectra. X-ray diffraction analysis shows that [CuL³]₂ is a dinuclear complex with an extremely distorted square-planar geometry. Furthermore, the antioxidant activities of the compounds have been investigated. The electrochemical properties of the Cu(II) complexes have also been studied by cyclic voltammetry. The Cu(II) complexes show similar superoxide dismutase (SOD) activity compared with that of the native Cu, Zn-SOD.     

Synthesis of 5-{[(1Hbenzo[d]imidazol-2-yl)sulfonyl]methyl}-3-phenyl-4,5-dihydroisoxazole derivatives,invitro antibacterial and antioxidant studies along with their insilico analyses

Synthesis of a series of novel sulfone derivatives 6(a-u) possessing benzimidazoles and isoxazoline rings tailored in a single molecule 5(a-u) was done by reactions using 5-(bromomethyl)-3-phenyl-4,5-dihydroisoxazoles 3(a-u) and 5-{[(1H-benzo[d]imidazol-2-yl)thio]methyl}-3-phenyl-4,5-dihydroisoxazoles 4(a-u) molecules. The chemical structures of all the newly synthesized compounds were established by IR, ¹HNMR, ¹³CNMR and LCMS spectral data. The biological characteristics of the novel sulfone compounds, such as their antioxidant and antibacterial activity, were evaluated. Among the synthesized sulfones derivatives, compounds 6 g, 6b, and 6e demonstrated outstanding antibacterial activity while compounds 6b, 6c, 6i, 6j, and 6 k demonstrated higher antioxidant activity. Further insilico absorption, distribution, metabolism, excretion, and toxicity (ADMET) studies of synthesized sulfones were studied which exhibited excellent intestinal absorption which is more than 80 %, and relatively moderate toxicity. Molecular docking studies confirmed the antibacterial and antioxidant potential which is comparable with the standard.     

Biosynthesis of Bixa orellana seed extract mediated silver nanoparticles with moderate antioxidant,antibacterial and antiproliferative activity

Biosynthesis of metallic silver nanoparticles (AgNPs) has gained much interest and offers an attractive alternate to physical and chemical approaches. In recent year several safe, easy, cost-effective, reproducible, and environmentally friendly synthesis approaches for silver nanoparticles have been developed. In this research work, a simple, cheap, and unexplored method was applied on green synthesis of AgNPs using secondary metabolites extracted from Bixa orellana seeds. The seeds are rich of flavonoids and phenolic compounds which presumably responsible for the fast reduction and stabilization of silver ion into silver nanoparticles. The biosynthesis process is very likely to be able to reduce silver ions under simple physiological conditions. The surface plasmon resonance (SPR) that was appeared at 420 nm in UV–vis spectrum, had confirmed the formation of AgNPs. Moreover, the functional groups in secondary metabolite that act as reducing, capping and stabilizing agents for silver nanoparticles, are identified by Fourier transform infrared (FTIR) spectra. An X-ray diffraction analysis generated four peaks for Bixa orellana seed extract mediated AgNPs positioned at 2θ angles of 38.1°, 44.2°, 64.6°, and 77.5° corresponding to crystal planes (1 1 1), (2 0 0), (2 2 0), and (3 1 1). Field emission scanning electron microscope (FESEM) and transmission electron microscopy (TEM) images confirmed the formation of nanosized silver particles. The z-average of the synthesized particles measured by dynamic light scattering (DLS) was found to be 92.9 nm. AgNPs synthesized exhibited remarkable antioxidant activity, antibacterial and antiproliferative activity against human breast (MCF-7) cell line. On the basis of our results, we conclude that biologically synthesized AgNPs exhibited favorable characteristics and have the potential to be used in biomedical fields.     

Synthesis,spectral characterization,antioxidant, anticancer in vitro,and DNA cleavage studies of a series of ruthenium(II) complexes bearing Schiff base ligands

Ruthenium(II) complexes with 2-acetylpyridine-thiosemicarbazones (L¹–L⁴) were synthesized and characterized by analytical and spectral (FT-IR, UV–vis, NMR [¹H, ¹³C and ³¹P], and ESI-Mass) methods. Systematic biological investigations, free radical scavenging, anticancer activities, and DNA cleavage studies, were carried out for the complexes. Antioxidant studies showed that the complexes have significant antioxidant activity against DPPH, hydroxyl, nitric oxide radicals and hydrogen peroxide assay. The in vitro cytotoxicity of complexes against breast cancer (MCF-7) cell line was assayed showing high cytotoxicity with low IC₅₀ values indicating their efficiency in destroying the cancer cells even at very low concentrations. The DNA cleavage studies showed that the complexes efficiently cleaved DNA.     

Synthesis, characterization and biological activity of polyketones

Polyketone resins have been prepared by the Friedel-Crafts polymerization of dithiophenylidenecyclopentanone (Ⅰ), dithiophenylidenecyclohexanone (Ⅱ) and dithiophenylideneacetone (Ⅲ) with adipoyl, sebacoyl and terephthaloyl dichlorides using boron trifluoride as catalyst and carbon disulphide as solvent. Polymers were characterized with IR, 1 H-NMR, and the results showed the presence of carbonyl of ketonic groups in the main chain. The polyketones have inherent viscosities of 0.40-0.70 dL/g. All the polymers are semicrystalline and most of them are partially soluble in most common organic solvents but freely soluble in aprotic solvents. The temperatures of 50% weight loss are as high as 185℃ to 280℃ in air, indicating that these aromatic polyketones have excellent thermal stability. All the polyketones were tested for their antimicrobial activity against bacteria and fungi.     

Synthesis,spectroscopic characterization and thermal studies of some rare earth metal complexes of unsymmetrical tetradentate Schiff base ligand

The solid complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III) and Gd(III) with 4-hydroxy-3-(1-{2-(2-hydroxy-benzylidene)-aminophenylimino}-thyl)-6-methy-pyran-2-one (H₂L) derived from o-phenylenediamine, 3-acetyl-6-methyl-(2H)pyran,2,4(3H)-dione (dehydroacetic acid or DHA) and salicylic aldehyde have been synthesized and characterized by elemental analysis, conductometry, magnetic susceptibility, UV–visible, FTIR, ¹H NMR spectra, X-ray diffraction, and thermal analysis and screened for antimicrobial activity. The FTIR spectral data suggest that the ligand behaves as a dibasic tetradentate ligand with ONNO donar atoms sequence towards central metal ion. From the microanalytical data, the stoichiometry of the complexes has been found to be 1:1 (metal:ligand). The physico-chemical data suggest distorted octahedral geometry for La(III), Ce(III), Pr(III), Nd(III), Sm(III) and Gd(III) complexes. The X-ray diffraction data suggest monoclinic crystal system for La(III) and Ce(III) and orthorhombic crystal system for Pr(III) and Nd(III) complexes. Thermal behaviour (TGA/DTA) of the complexes was studied and kinetic parameters were determined by Horowitz–Metzger and Coats–Redfern methods. The ligand and their metal complexes were screened for antibacterial activity against Staphylococcus aureus, Escherichia coli and Bacillus sp. Fungicidal activity against Aspergillus niger, Trichoderma and Fusarium oxysporum.     

Chemical composition,antibacterial and antioxidant activities of essential oils from leaves of three Melaleuca species of Pakistani flora

This study presents essential oil composition of three Melaleuca species namely, Melaleuca bracteata F. Muell, Melaleuca fulgens R. Br. subsp. steedmanii and Melaleuca leucadendron (L.) L. collected from different regions of Pakistan. The chemical composition of essential oils was analyzed by GC-FID and GC–MS. Eugenol methyl ether was identified as a principal component in M. bracteata (82.3%), M. fulgens (87.8%) and M. leucadendron (95.4%) oils. In vitro antibacterial studies were done by agar well diffusion and microdilution method and the tested essential oils exhibited bacteriostatic and bactericidal effects against the tested foodborne pathogens at 4–8 µg/ml. Time kill assay showed significant bactericidal effect of oils for four weeks. The antioxidant potential was assessed by free radical scavenging activity and reducing power assay. The oils showed strong antioxidant activity with approximately 89.0–89.5% inhibition of 2,2-diphenyl-1-picrylhydrazyl radical and ferric reducing power in the range of 1.94 ± 0.007–2.04 ± 0.04% at 100 µg/ml.     

左旋多巴胺Schiff碱的合成,表征和抗菌活性

近来,资料表明Schiff碱作为相转移催化烷基化的良好中间体,在药物合成、催化、分析化学等领域有着重要应用。Schiff碱及其衍生物与金属形成的配合物具有抑菌、杀菌、抗肿瘤、抗病毒等多方面的生物活性,在医学领域有广泛的应用前景[1,2]。本文利用广西丰富的天然资源左旋多巴为原料,与芳香醛酮反应,合成并表征了8种左旋多巴胺Schiff碱(其中4-硝基苯甲醛、香兰醛、4-氯苯甲醛、肉桂醛、大茴香醛及水杨醛缩多巴胺Schiff碱未见文献报道),并研究它们对金黄色葡萄球菌、大肠杆菌的体外抑菌活性。1实验部分1·1药口和试剂硅胶GH254、硅胶H(200-3…     

Synthesis,characterization, antibacterial,and thermal studies of unsymmetrical Schiff-base complexes of cobalt(II)

Cobalt(II) complexes of a new series of unsymmetrical Schiff bases have been synthesized and characterized by their elemental analyses, melting points, magnetic susceptibility, thermogravimetric analysis, differential scanning calorimetry, infrared (IR), and electronic spectral measurements. The purity of the ligands and the metal complexes are confirmed by microanalysis, while the unsymmetrical nature of the ligands was further corroborated by ¹H-NMR. Comparison of the IR spectra of the Schiff bases and their metal complexes confirm that the Schiff bases are tetradentate and coordinated via N₂O₂ chromophore. The magnetic moments and electronic spectral data support square-planar geometry for the cobalt(II) complexes. The complexes were thermally stable to 372.3°C and their thermal decomposition was generally via the partial loss of the organic moiety. The Schiff bases and their complexes were screened for in vitro antibacterial activities against 10 human pathogenic bacteria and their minimum inhibitory concentrations were determined. Both the free ligands and cobalt(II) complexes exhibit antibacterial activities against some strains of the microorganisms, which in a number of cases were comparable with, or higher than, that of chloramphenicol.     

Formation of diaryl sulfides and sulfoxides: Synthesis,characterization and structure activity correlation studies

Abstract

The synthesis of a series of stable diarylsulfides and sulfoxides is reported. All the newly synthesized compounds were characterized by ¹H, ¹³C NMR and mass spectroscopic techniques. A detailed mechanistic study indicates that the formation of sulfoxides follows the oxidation. In addition to synthesis, characterization and mechanistic studies, the glutathione peroxidase(GPx) mimetic activity of the newly synthesized compounds is described. It is observed that the diaryl sulfides having a heterocyclic ring attached to the nitrogen atom facilitates the oxidation of the sulfur center to form the corresponding sulfoxides. The substituents attached to the nitrogen atom play an important role in the catalytic activity of the substituted diaryl sulfides. The obtained data supports for the higher antioxidant activity of diaryl sulfides than that of the corresponding sulfoxides.     

Novel methacrylate copolymers with fluorine containing: Synthesis, characterization, reactivity ratios, thermal properties and biological activity

New methacrylate based monomers 2-(4-benzoylphenoxy)-2-oxoethyl-2-methylacrylate (BOEMA), 2-(4-acetylphenoxy)-2-oxoethyl-2-methylacrylate (AOEMA), and 2-[(4-fluorophenyl)amino]-2-oxoethyl-2-methylacrylate (FPAMA), were synthesized first time. The free-radical-initiated copolymerization of AOEMA and BOEMA with FPAMA were carried out in 1,4-dioxane solution at 65 °C using 2,2′-azobisisobutyronitrile (AIBN) as an initiator with different monomer-to-monomer ratios in the feed. The monomers and copolymers were characterized by FTIR, ¹H NMR and ¹³C NMR spectral studies. The copolymer compositions were evaluated by nitrogen content in polymers. The reactivity ratios of the monomers were determined by the application of Fineman-Ross and Kelen-Tudos methods. The analysis of reactivity ratios revealed that BOEMA and AOEMA are less reactive than FPAMA, and copolymers formed are statistically in nature. The molecular weights ( and ) and polydispersity index of the polymers were determined using gel permeation chromatography. Thermogravimetric analysis of the polymers reveals that the thermal stability of the copolymers increases with an increase in the mole fraction of FPAMA in the copolymers. Glass transition temperatures of the copolymers were found to decrease with an increase in the mole fraction of FPAMA in the copolymers. The prepared homo and copolymers were tested for their antimicrobial activity against bacteria, fungi and yeast.     

Synthesis of Cu-TiNT,characterization, and antibacterial properties evaluation

Copper ion–exchanged titanate nanotubes (Cu-TiNTs) had been prepared from a simple ion-exchange reaction between copper salt and sodium titanate nanotubes (Na-TiNT) which was synthesized by alkaline hydrothermal synthesis starting from titanium oxide of anatase phase. A thorough structural and morphological characterization of Cu-TiNT (and Na-TiNT) was done by using various material characterization techniques, such as X-ray diffraction, Raman spectroscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy to reveal retention of tubular structure of titanate nanotubes with decoration of copper (II) oxide on the surface of the tubes as well as an exchange of Na⁺ ion by Cu²⁺ ion in the interlamellar space. The antibacterial properties of the Cu-TiNT were evaluated by broth macrodilution method using microtiter trays, with concentration ranging between 512 and 0.5 μg/mL. The Cu-TiNT demonstrated no clinically relevant antibacterial activity alone (minimum inhibitory concentration ≥ 1024 μg/mL), but when associated with gentamicin, this compound enhanced the antibiotic activity of this drugs against strains of Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. The results were very promising to the utilization of the Cu-TiNT as an adjuvant to the antibiotic therapy.