Synthesis and characterization studies of 3-formyl chromone Schiff base complexes and their application as antitumor,antioxidant and antimicrobial

A novel Schiff base namely (E)-3-((2,6-dihydroxypyrimidin-4-ylimino)methyl)-4H-chromen-4-one and its Co (II), N (II)i, Cu (II) and Cd (II) complexes have been synthesized and proved by elemental analysis, molar conductance, thermal analysis (TGA), Inductive Coupled plasma (ICP), magnetic moment measurements, X-ray powder diffraction, IR, EI-mass,¹H NMR, ¹³C NMR,UV–Vis. and ESR spectral studies. On the basis of these data, it is evident that the Schiff base acts as bidentate via oxygen atom of carbonyl group and azomethine nitrogen atom for Co (II) complex; monobasic bidentate ligand for Ni (II), Cu (II) and Cd (II) complexes via oxygen atom of hydroxyl group and nitrogen atom of pyrimidine ring. The results showed all complexes have octahedral geometry. The average particle size of the ligand and its complexes were found to be 1.010–0.343 nm. The pharmacological action (antioxidant, antimicrobial and anticancer) of the prepared compounds is studied. The antitumor activity of the ligand and its metal complexes is evaluated against human liver carcinoma (HEPG2) cell. The data displayed the Co (II) complexes strong cytotoxicity where IC₅₀ values of Co (II) complex and 5-fluorouracil (stander drug) are 9.33 and 7.86 μg/ml respectively. The Co (II) and Cd (II) complexes have antibacterial activity more than ampicillin (stander drug). The interaction of the synthesized compounds with calf-thymus DNA (CT-DNA) has been performed via absorption spectra and viscosity technique. The DNA- binding constants have been determined.     

Green synthesis and chemical characterization of silver nanoparticles obtained using Allium saralicum aqueous extract and survey of in vitro antioxidant,cytotoxic, antibacterial and antifungal properties

Allium saralicum R.M. Fritsch has been used in Iranian traditional medicine as a remedial supplement for microbial diseases. This paper reports the green synthesis, chemical characterization and antioxidant, cytotoxic, antibacterial and antifungal properties of silver nanoparticles obtained using aqueous extract of A. saralicum leaves. In this synthesis, no surfactants or stabilizers were used. For characterization, UV–visible spectroscopy, transmission electron microscopy, X‐ray diffraction, energy‐dispersive X‐ray spectroscopy and field emission scanning electron microscopy were used. 2,2‐Diphenyl‐1‐picrylhydrazyl was used in experiments to assess the antioxidant potential of the silver nanoparticles, which revealed an impressive prevention in comparison with butylated hydroxytoluene. The synthesized silver nanoparticles at low doses (1–250 μg dl^?1) did not show marked cytotoxic activity (against cervical cancer cells (Hela), breast cancer cells (MCF‐7) and human embryonic kidney cells (HEK‐293)). Agar diffusion tests were applied to determine the antibacterial and antifungal characteristics. Compared with all standard antimicrobials, the silver nanoparticles showed higher antibacterial and antifungal activities (p ≤ 0.01). Also, the silver nanoparticles inhibited the growth of all bacteria and fungi at concentrations of 31–250 μg ml^?1, and destroyed them at concentrations of 31–500 μg ml^?1 (p ≤ 0.01). Because the silver nanoparticles obtained using aqueous extract of A. saralicum leaves have antioxidant, non‐cytotoxic, antifungal and antibacterial potentials, they can be used as a medical supplement or drug.     

N‐Phenyl‐substituted carbene precursors and their silver complexes: synthesis,characterization and antimicrobial activities

A series of unsymmetrically substituted N‐heterocyclic carbene (NHC) precursors ( 1a , 1b , 1c , 1d , 1e ) were synthesized from the reaction of N‐phenylbenzimidazole with various alkyl halides. These compounds were used to synthesize NHC–silver(I) complexes ( 2a , 2b , 2c , 2d , 2e ). The five new 1‐phenyl‐3‐alkylbenzimidazolium salts ( 1a , 1b , 1c , 1d , 1e ) and their NHC–silver complexes ( 2a , 2b , 2c , 2d , 2e ) were characterized by the ¹H NMR, ¹³C NMR and FT‐IR spectroscopic methods and elemental analysis techniques. Also, the two NHC–silver complexes 2b and 2c were characterized by single‐crystal X‐ray crystallography, which confirmed the linear C―Ag―Cl arrangements. The antibacterial activities of the NHC precursor and NHC–silver complexes were tested against three Gram‐positive bacterial strains (Bacillus subtilis, Listeria monocytogenes and Staphylococcus aureus) and three Gram‐negative bacterial strains (Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa) using the microdilution broth method. The NHC–silver complexes showed higher antibacterial activity than the NHC precursors. In addition, silver complexes 2a , 2b , 2c , 2d showed high antibacterial activity against the Gram‐positive bacteria L. monocytogenes and S. aureus compared to the standard, tetracycline. Copyright © 2014 John Wiley & Sons, Ltd.     

Surface antimicrobial modification of polyamide by poly(hexamethylene guanidine) hydrochloride

Antimicrobial polyamide (PA) received much attention for the demand of packaging and biomedical fields. In this paper, an antimicrobial PA6 membrane was prepared via a surface chemical reaction. A highly effective antibacterial component (PHMG‐E) with terminal epoxy group was firstly synthesized via a reaction between polyhexamethylene guanidine hydrochloride (PHMG) and ethylene glycol diglycidyl ether (EGDE). Then, PHMG‐E was bonded on the surface of PA6 membrane with secondary amine reduced by borane‐tetrahydrofuran (BH₃‐THF). The antimicrobial rates of surface‐modified PA6 membrane (PA6‐PHMG) against Escherichia coli and Staphylococcus aureus were both higher than 99.99%, and the PHMG was non‐leaching due to the chemical bonding. The hydrophilicity of antibacterial PA6 membrane was also significantly improved and the mechanical performance became better.     

Lactoferrin and Its Derived Peptides: An Alternative for Combating Virulence Mechanisms Developed by Pathogens

Due to the emergence of multidrug-resistant pathogens, it is necessary to develop options to fight infections caused by these agents. Lactoferrin (Lf) is a cationic nonheme multifunctional glycoprotein of the innate immune system of mammals that provides numerous benefits. Lf is bacteriostatic and/or bactericidal, can stimulate cell proliferation and differentiation, facilitate iron absorption, improve neural development and cognition, promote bone growth, prevent cancer and exert anti-inflammatory and immunoregulatory effects. Lactoferrin is present in colostrum and milk and is also produced by the secondary granules of polymorphonuclear leukocytes, which store this glycoprotein and release it at sites of infection. Lf is also present in many fluids and exocrine secretions, on the surfaces of the digestive, respiratory and reproductive systems that are commonly exposed to pathogens. Apo-Lf (an iron-free molecule) can be microbiostatic due to its ability to capture ferric iron, blocking the availability of host iron to pathogens. However, apo-Lf is mostly microbicidal via its interaction with the microbial surface, causing membrane damage and altering its permeability function. Lf can inhibit viral entry by binding to cell receptors or viral particles. Lf is also able to counter different important mechanisms evolved by microbial pathogens to infect and invade the host, such as adherence, colonization, invasion, production of biofilms and production of virulence factors such as proteases and toxins. Lf can also cause mitochondrial and caspase-dependent regulated cell death and apoptosis-like in pathogenic yeasts. All of these mechanisms are important targets for treatment with Lf. Holo-Lf (the iron-saturated molecule) can contain up to two ferric ions and can also be microbicidal against some pathogens. On the other hand, lactoferricins (Lfcins) are peptides derived from the N-terminus of Lf that are produced by proteolysis with pepsin under acidic conditions, and they cause similar effects on pathogens to those caused by the parental Lf. Synthetic analog peptides comprising the N-terminus Lf region similarly exhibit potent antimicrobial properties. Importantly, there are no reported pathogens that are resistant to Lf and Lfcins; in addition, Lf and Lfcins have shown a synergistic effect with antimicrobial and antiviral drugs. Due to the Lf properties being microbiostatic, microbicidal, anti-inflammatory and an immune modulator, it represents an excellent natural alternative either alone or as adjuvant in the combat to antibiotic multidrug-resistant bacteria and other pathogens. This review aimed to evaluate the data that appeared in the literature about the effects of Lf and its derived peptides on pathogenic bacteria, protozoa, fungi and viruses and how Lf and Lfcins inhibit the mechanisms developed by these pathogens to cause disease.     

基于无机纳米材料的抗菌抗病毒功能涂层和薄膜

COVID-19在全球的大流行对人类的健康生活和社会的正常运行都造成了严重的危害. 阻断致病微生物通过受污染表面与人类间接接触传播, 或者避免与其直接接触是保护我们免受伤害的主要方法. 目前的解决措施包括设计开发抗菌抗病毒表面涂层和研发由自清洁薄膜或织物制成的个人防护设备. 综述了近年来几种研究广泛的金属、金属氧化物、金属有机框架材料等用于抗菌抗病毒涂层或薄膜的工作, 对其作用机制和微生物灭活效果进行了总结讨论, 并且评估了其本身的毒性以及实际应用的局限性, 最后就抗菌抗病毒涂层和薄膜开发的挑战和新兴研究方向提出了未来展望.     

Synthesis,structural, spectroscopic,and thermal studies of some transition-metal complexes of a ligand containing the amino mercapto triazole moiety

A new series of transition-metal complexes of Schiff base ligand containing the amino mercapto triazole moiety ( HL ) was prepared. The Schiff base and its metal complexes were elucidated by different spectroscopic techniques (infrared [IR], ¹H nuclear magnetic resonance, UV–Visible, mass, and electron spin resonance [ESR]), and magnetic moment and thermal studies. Quantum chemical calculations have been carried out to study the structure of the ligand and some of its complexes. The IR spectra showed that the ligand is chelated with the metal ion in a neutral, tridentate, and bidentate manner using NOS and NO donors in complexes 1 – 6 , 10–12 , and 7 and 8 , respectively, whereas it behaves in a monobasic tridentate fashion using NOS donor sites in copper(II) nitrate complex ( 9 ). The magnetic moment and electronic spectra data revealed octahedral and square pyramidal geometries for complexes 2 , 11 , 12 , and 5 – 8 and 10 , respectively. However, the other complexes were found to have tetrahedral ( 4 ), trigonal bipyramidal ( 1 and 3 ), and square planar ( 9 ) structures. Thermal studies revealed that the chelates with different crystallized solvents undergo different types of interactions and the decomposition pathway ended with the formation of metal oxygen (MO) and metal sulfur (MS) as final products. The ESR spectrum of copper(II) complex 10 is axial in nature with hyperfine splitting with ²B_1g as a ground state. By contrast, complexes 7 and 8 undergo distortion around the Cu(II) center, affording rhombic ESR spectra. The HL ligand and some of its complexes were screened against two bacterial species. Data showed that complex 12 demonstrated a better antibacterial activity than HL ligand and other chelates.     

基于双苯并咪唑及二羧酸配体配合物的合成、结构及抗菌活性

利用双苯并咪唑基配体4,4′-二(苯并咪唑-1-甲基)联苯(bbmb)与V形二羧酸配体4,4′-二羧苯基醚(H2dcpe)合成了配合物{[Ni(bbmb)(dcpe)(H_2O)]·2H_2O}_n(1)和{[Mn_2(bbmb)(dcpe)_2(H_2O)]·1.5H_2O}_n(2)。通过红外、元素分析、X射线单晶衍射、热重分析等检测手段对配合物结构进行了表征。配合物1是具有sql拓扑构型的二维层状化合物。配合物2呈现出含有四核锰构型的二维层状结构。体外抗菌实验证明2个配合物都表现出良好的抗菌活性。     

Synthesis,characterization, crystal structure,and antimicrobial studies of novel thiourea derivative ligands and their platinum complexes

N,N-Di-R-N′-(4-chlorobenzoyl)thiourea (Di-R: diethyl, di-n-propyl, di-n-butyl and diphenyl) ligands (HL^1–4) and their Pt(II) complexes (cis-[Pt(L^1–4-S,O)₂]) have been synthesized and structurally characterized by elemental analyses, FT-IR and NMR spectroscopy. HL² ligand and cis-[Pt(L⁴-S,O)₂] metal complex have been also characterized by a single-crystal X-ray diffraction study. HL², C₁₄H₁₉ClN₂OS, crystallizes in the monoclinic space group P2₁/n (no. 14), with Z = 4, and unit cell parameters, a = 11.1405(16) Å, b = 9.7015(12) Å, c = 14.790(2) Å, β = 106.547(7)°. The cis-[Pt(L⁴-S,O)₂], C₄₀H₂₈Cl₂N₄O₂PtS₂: triclinic, space group P-1 (no. 2), a = 8.9919(3) Å, b = 14.7159(6) Å, c = 15.7954(6) Å, α = 113.9317(18)°, β = 97.4490(18)°, and γ = 105.0492(16)°. Single crystal analysis of complex, cis-[Pt(L^1–4-S,O)₂], revealed that a square planar coordination geometry is formed around the platinum atom by two sulfur and two oxygen atoms of the related ligands, which are in a cis configuration. In addition, the thiourea derivative ligands and their complexes were evaluated for both their in-vitro antibacterial and antifungal activity. The results have been reported, explained, and compared with fluconazole and ampicillin, used as reference drugs.     

由4-氯-6-[2-(吡嗪-2-基亚甲基)肼基]嘧啶构筑的一维银配合物及其抗氧化和抑菌性能

由4-氯-6-[2-(吡嗪-2-基亚甲基)肼基]嘧啶(HL)和硝酸银合成了一维链状配位聚合物[Ag(C_(10)H_9N_6Cl)(NO_3)]_n(1)。在配合物1中,中心Ag离子与来自配体吡嗪环上的N5原子及另一配体上的N1、N4、N6原子进行配位,形成了锯齿形的一维链状结构。此外,锯齿形一维链通过N—H…O和N—H…N氢键相互作用及π-π堆积形成了三维的超分子结构。研究结果表明,与配体HL相比配合物1对超氧负离子和羟基自由基具有更强的自由基清除效能;配合物1对不同细菌的抗菌效果也优于配体HL。