Antimicrobial Activity Of Complexes Research Articles

1D and 2D Coordination Polymers of Calcium with Nonsteroidal Anti-Inflammatory Drugs: Synthesis, Crystal Structures, Hirshfeld Surfaces, Antimicrobial and Antioxidant Activities.

Four alkaline earth metal complexes of ketoprofen (Hket) and indomethacin (Hind) were synthesized and characterized: [Ca(ket)2(H2O)2]n (1), [Mg(ket)2(H2O)2] (2), [Ca(ind)2(EtOH)2]n (3), and [Mg(ind)2(EtOH)2] (4). All compounds were studied by elemental analysis (EA), flame atomic absorption spectrometry (FAAS), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Crystal structures of 1 and 3 were determined by single crystal X-ray diffraction technique T=100 K. The structure of 1 is dominated by a one-dimensional coordination polymer, while 3 is formed by a two-dimensional layer stabilized by the calcium zig-zag chains and π⋅⋅⋅π stacking interactions. Crystal packing arrangements were characterized by fingerprint plots (FPs) that were derived from the Hirshfeld surfaces (HSs). The antioxidant and antimicrobial activities of complexes were evaluated against Gram-positive and Gram-negative bacteria as well as yeasts.

Synthesis, crystal structures, CT-DNA/BSA binding modes and antibacterial activities of Zn(II) and Cr(III) with an acylhydrazone ligand

Two salicylaldehyde-4-hydroxy phenylacetyl acylhydrazone transition metal complexes ZnL2·H2O (I) and [CrL2]NO3·EtOH (II) were synthesized by C15H14N2O3 (HL) with Zn(NO3)2·6H2O and Cr(NO3)3·9H2O. Structures of HL, I and II were characterized by single crystal X-ray diffraction. With the ligand HL belonging to the monoclinic crystal system and the P21/c space group, the coordinating atoms (N and O atoms) in both two complexes I and II exhibited a six-coordinated octahedral geometry centered on the metal ion. Thermal stabilities of the two complexes were analyzed by TG-DTG techniques, which illustrated the maximum thermal decomposition peak temperatures of two complexes were both higher than 170 °C, exhibiting strong thermal stabilities. UV–vis absorption spectroscopy and microcalorimetry were used to determine interaction patterns of I and II with CT-DNA, showing that I and II effectively bound to CT-DNA through the intercalation mode and the interactions processes of I and II with CT-DNA were spontaneous, exothermic entropy reduction reactions. Fluorescence spectroscopy and microcalorimetry were used to determine the interactions of I and II with BSA, presenting that the two complexes can effectively bind to BSA and form non-fluorescent matrix complexes and the interactions processes were spontaneous exothermic and entropy reducing, and each of interaction duration was within 48 min. In addition, the antimicrobial activities of complexes I and II against S. aureus, P. aeruginosa, B. subtilis and E. coli were determined, revealing II exhibited stronger inhibition activity against P. aeruginosa than gentamicin sulfate at 0.5 mg·L-1. Complexes I and II were expected to be used as alternative drugs of gentamicin sulfate in the future.

Synthesis, Characterization and Antimicrobial Properties of Mixed-Ligand Complexes of Some Metal(II) Ions with Barbituric Acid and 1,10-Phenanthroline Ligands

Many pathogenic organisms have developed resistance to many antibiotics, which leads to an increase in the spread of many microbial infections. There is an urgent need to find more effective drugs to curb widespread transmission. Hence, this study synthesized and evaluated the antimicrobial activities of mixed-ligand complexes of Cu(II), Co(II), Ni(II), Mn(II), and Zn(II) ions with barbituric acid and 1,10 phenanthroline ligands in effort to find more effective antibiotics. The complexes were characterized using elemental analysis, metal analysis, melting points, solubility tests, and spectroscopic analyses (IR and UV-visible). The antimicrobial activities of the complexes were evaluated against two gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus), two gram-negative bacteria (Pseudomonas aeruginosa and Clostridium spp.), and four pathogenic fungi (Candida albicans, Aspergillus flavus, Aspergillus niger, and Saccharomyces cerevisiae). The biological activities of the metal complexes were compared to the activities of some conventional antibiotics. The molecular formulas for the complexes in 1:1:1 (L-M-L) were established based on the results of the elemental and metal analyses. The IR spectroscopic data results showed the coordination of 1,10-phenanthroline to the metal ions through the nitrogen donor atom, while barbituric acid coordinated with the metal ions through nitrogen and oxygen atoms. The formation of the complexes was confirmed by UV-visible spectroscopic data. Many of the mixed-ligand metal complexes demonstrated higher biological activities than the standard drugs and also succeeded where the conventional antibiotics failed. Therefore, the metal complexes could be considered as more efficacious antibiotics that could be added to the arsenal of effective antibiotics for the prevention of the intrinsic problems of multidrug resistance.
 Keywords: Bacteria, Fungi, Ligands, Metal complexes, Multidrug resistance, Barbituric acid

Supramolecular Structure and Antimicrobial Activity of Ni(II) Complexes with s-Triazine/Hydrazine Type Ligand

The two complexes, [Ni(DPPT)2](NO3)2*1.5H2O (1) and [Ni(DPPT)(NO3)Cl].EtOH (2), were synthesized using the self-assembly of (E)-2,4-di(piperidin-1-yl)-6-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)-1,3,5-triazine (DPPT) with Ni(NO3)2*6H2O in the absence and presence of NiCl2*6H2O, respectively. In both cases, the neutral tridentate DPPT ligand is found coordinated to the Ni(II) via three N-atoms from the hydrazone, pyridine and s-triazine rings. Hence, the homoleptic complex 1 has a NiN6 hexa-coordination environment while two NO3− are counter anions in addition to one-and-a-half crystallized hydration water molecules are found acting as an outer sphere. The heteroleptic complex 2 has a NiN3O2Cl coordination sphere where the coordination environment of the Ni(II) is completed by one bidentate nitrate and one chloride ion leading to a neutral inner sphere while the outer sphere contains one crystallized ethanol molecule. Both complexes have distorted octahedral coordination environments around the Ni(II) ion. Using Hirshfeld analysis, the intermolecular contacts H…H and O…H in 1 and the Cl…H, O…H, N…H, H…H, C…H and C…C in 2 are found to be the most important for crystal stability. The antimicrobial activity of complexes 1 and 2 was assessed against different bacterial and fungal strains, and the results were compared with the free ligand as well as the antibacterial (Gentamycin) and antifungal (Ketoconazole) positive controls. Both Ni(II) complexes are better antibacterial and antifungal agents than the free ligand. Interestingly, both Ni(II) complexes have similar antifungal activity against C. albicans compared to Ketoconazole.

Preparation, Structures and Antimicrobial Activity of Ni(II) Complexes on the Base of Enrofloxacin with Dicumarol Derivative

Objective: To synthesize Ni(II) complexes on the base of enrofloxacin with dicumarol derivative and to investigate their antioxidant and antimicrobial potentials. Methods: Ni(II) complexes have been synthesized by classical thermal methods by mixing aqueous metal solutions with ethanol ligands and enrofloxacin in a 1:1 molar ratio. A biologically strong ligand was prepared by refluxing a dicoumarol derivative in aldehyde and ethanol. The structures of the ligands and their nickel complexes were investigated and confirmed by elemental analysis, FT-IR, 1H-NMR, 13C-NMR and mass spectroscopy. The thermal behavior of newly synthesized mixed-ligand Ni(II) complexes was studied by thermogravimetric analysis. Ferric-reducing antioxidant power (FRAP) (antioxidant activity) of all complexes were measured. All the compounds were screened for their antimicrobial activity against E. coli; P. aeruginosa; S. pyogenes; C. albicans and A. niger using Luria Broth dilution method for MIC values. Both the ligand and its complex were screened for antioxidant and antimicrobial activity in vitro. Findings: Antioxidant and antimicrobial activities of complexes were found to be better than the parent ligands used for complex formation. MIC values for complex C5 (-CH3 derivative) were found to be between 40-70 mg/mL and FRAP values was 82.44 mmol/100g, indicative of its ferric reducing antioxidant power. These result show that complex C5 (-CH3 derivative) was found more potential as antimicrobial and antioxidant agent. Novelty : The coordination of metal complex with enrofloxacin (antibiotic) draws a scheme for the synthesis of new drug as well as increasing the activity of enrofloxacin that is currently in use. Current work supports that the activity of antibiotics could be increased by coordination of metal ion complex. There could be a possibility that these complexes allow to reduce the dose of drug introduced into the body. Keywords: Dicumarol; Antimicrobial; Antioxidant; Thermal Analysis; TGA

Structural characterization and antimicrobial evaluation of chromium(III) and cobalt(III) complexes with 2,2-diMe-1,3-pdta: Tuning dimensionality of coordination polymer and the water content by alkyl substitution

Hexadentate 2,2-dimethyl-1,3-propanediamine-N,N,N’,N’-tetraacetate (2,2-diMe-1,3-pdta) ligand, containing two methyl substituents at the central carbon atom of a 1,3-propanediamine, has been prepared and used for the synthesis of Na[Cr(2,2-diMe-1,3-pdta)]·3.75H2O (1) and Na[Co(2,2-diMe-1,3-pdta)]·3.88H2O (2) complexes. These complexes were characterized by IR and electronic absorption spectroscopy, and single-crystal X-ray diffraction analysis. NMR (1H and 13C) spectroscopy was additionally applied for the characterization of complex 2. Crystallographic data indicate that the two investigated crystals are isostructural and contain 2,2-diMe-1,3-pdta ligand coordinated to metal ion through 2N and 4O atoms forming an octahedral complex in which the six-membered 1,3-propanediamine chelate ring adopts a twist-boat conformation. There are four such complex anions in the symmetry independent part of the unit cell. Each complex anion is further connected to the sodium counterion(s) via the bridging carboxylate group(s). Structural changes in 2,2-diMe-1,3-pdta-Cr(III) complex stimulated solely by the presence of alkyl side groups are discussed. The present study shows that in 1,3-pdta-type complexes of Cr(III) and Co(III), the environment at coordination centre can be modified by introducing substitution in one of the carbon atoms of the diamine and the resulting difference in the subunit structure can bring about noticeable change in molecular and crystal structure. The examples illustrate the importance of the steric effect for the fine tuning of the dimensionality of the resulting coordination polymer and the water content. The antimicrobial activity of complexes 1 and 2 was evaluated against different bacterial and Candida spp., while their cytotoxic effects were tested on the normal human lung fibroblast cell line (MRC-5).

Synthesis, Structure, and Antimicrobial Activity of Complexes of Bivalent Metals with 1-Naphthylacetic Acid

Synthesis, Structure, and Antimicrobial Activity of Complexes of Bivalent Metals with 1-Naphthylacetic Acid

Cu(II), Co(II), Mn(II) complexes with 5-phenyltetrazole and polypyridyl ligands: Synthesis, characterization and evaluation of the cytotoxicity and antimicrobial activity

In this work, six new mixed-ligand Cu(II), Co(II), Mn(II) complexes with 5-phenyltetrazole (HL) and polypyridine ligands (phen – 1,10-phenanthroline, dmbipy – 2,2′-bi-4-picoline, dmphen – 4,7-dimethyl-1,10-phenanthroline, phendione – 1,10-phenanthroline-5,6-dione), namely, [Cu(dmbipy)(L)2] (1), [Cu2(dmphen)2(L)4] (2), [Cu(phendione)(L)2] (3), [Co3(phen)2(L)6] (4), [Mn3(phen)2(L)4(OAc)2] (5), [Mn(H2O)4(phen)]·phen·2L (6), are reported. Complexes have been characterized by EPR and IR-spectroscopy, elemental, thermogravimetric and powder X-ray diffraction analysis. Molecular structures of [Cu(dmphen)2L]·L·6H2O (2a), [Co3(phen)2(HL)2(L)4(OH)2]·1.9EtOH·1.1DMSO (4a), [Mn3(phen)2(L)4(OAc)2]·H2O (5·H2O) and [Mn(H2O)4(phen)]·phen·2L (6) have been determined by single crystal X–ray diffraction. The UV–vis spectroscopy has been applied to study the behavior of the compounds in solution. All complexes have been screened in vitro for their cytotoxic activity against human cancer cell lines: larynx carcinoma (Hep2), hepatocellular carcinoma (HepG2) and breast adenocarcinoma (MCF-7). Cu(II) complexes exhibit significant dose-dependent cytotoxic effect: [Cu2(dmphen)2(L)4] (2), [Cu(phendione)(L)2] (3) are found to be the most cytotoxic. The antimicrobial activity of complexes and ligands has been investigated against Escherichia coli, Staphylococcus aureus, Penicillium italicum and Colpoda steinii.

Synthesis, characterization, DFT calculation, DNA binding and antimicrobial activities of metal complexes of dimedone arylhydrazone

The diazotization, coupling and metallization process was employed to create hydrazone chelating ligand (HL) and its Co(II), Cu(II) and Ni(II) complexes. Elemental analysis, FT-IR, UV–visible, thermal analysis, 1H NMR, and 13C NMR were utilized to propose their structures. The reaction between metal (II) with HL produced mononuclear complexes and the molar conductivity results demonstrated that the complexes are all non-electrolytes that fall within a certain range 8–12 Ω−1 cm2 mol−1. Co(II) and Ni(II) complexes have pseudooctahedral coordination geometry, whereas Cu(II) complexes have square planar coordination geometry. The metal ion interacts with the ligand. as a monobasic bidentate by (CO) as well as deprotonating hydrazone moiety (NH). Besides, the optimized structure, bond lengths, and angles of the ligand and its complexes determined quantum chemical parameters were estimated by molecular modeling. Electronic absorption dilution and viscosity analysis techniques were used to study the compounds' DNA binding activities. With a binding constant in the 5.13 × 105 M−1 range. The results revealed that the complexes bind to CT-DNA in grooves followed by partial incorporation of the ligand between the DNA base stacks. The cytotoxicity of the new complexes was examined versus human carcinoma cell lines, HepG-2 & MCF-7, and compared to positive controls as vinblastine and colchicine. The DPPH free radical-scavenging assay was used to evaluate the anti-oxidant capacity of all compounds in-vitro. Finally, the antimicrobial activities of the complexes against fungal (Candida albicans), gram negative bacteria (Escherichia coli), and gram positive bacteria (Escherichia coli) were investigated using the disc-diffusion process (Staphylococcus aureus).

Gold(III) bisdithiolate complexes: molecular conductors that also exhibit anticancer and antimicrobial activities

Introduction Au(III) complexes with dithiolene ligands have been used as molecular conductors and magnetic materials [1]. These compounds feature square planar geometries, as that for cisplatin the Pt(II)-based compound in clinical use as chemotherapeutic drug. Based on the molecular structure, a similar mechanism of action, e.g. antitumor activity and interaction with DNA should be expected for these compounds. Reports on the biological activity of similar gold(III) compounds are relatively scarce in the literature. Only recently, a Au(III) 1,2-dithiolene cyclometalated complex had proved its potential against Gram-positive bacteria [2]. In this study we evaluated two related Au(III) complexes containing N-alkyl-1,3-thiazoline-2-thione dithiolate ligand, [Au(R-thiazdt)2]−1 (R = ethyl-1; R = hydroxyethyl-2) [3a,b] as antitumor and antimicrobial agents. The compounds were assessed in vitro towards cisplatin sensitive ovarian cancer cells (A2780), bacteria and fungus of clinical importance such as Staphylococcus aureus and Candida. Spectroscopic studies were also performed to evaluate the interaction with DNA. Materials and methods The gold complexes were synthesised as previously described [3a,b]. The cytotoxic activity against the A2780 ovarian cancer cells was assessed by the IC50 determined by the MTT assay. The antimicrobial activities of complexes 1 and 2 were assessed by the MIC values towards the Gram+ S. aureus, and the fungal strains C. glabrata and C. albicans, using reported methods [4,5]. The ability of compounds to bind to DNA was assessed by fluorescence spectroscopy using ethidium bromide (EB) as the fluorescence probe. Results Complexes 1 and 2 presented high cytotoxic activity in the cisplatin sensitive A2780 cells even superior than cisplatin. Complex 1 was able to inhibit the growth of S. aureus and both Candida strains, while 2 was much less active. The fluorescence studies revealed a weak interaction of compounds with CT-DNA, in contrast with that found for cisplatin, although the interaction of 2 is somewhat stronger than that found for 1. Discussion and conclusions Results evidenced the importance in what way minor modifications of the Au dithiolate structure can result in loss of activity in particular the antimicrobial activity. In contrast with cisplatin, DNA is not the main target involved in their mode of action. Further studies are needed to explore other potential targets and the mechanism of action.

Mixed-ligand manganese(II) complexes with 5-phenyltetrazole and polypyridine derivatives: Synthesis, crystal structures and biological activity

Mixed-ligand manganese(II) complexes [Mn3(bipy)2L4(OAc)2] (1), [Mn2(dmbipy)2L2(OAc)2] (2) and [Mn(dmphen)2L2] (3), where L – 5-phenyltetrazolate anion, bipy – 2,2′-bipyridine, dmbipy – 2,2′-bi-4-picoline, dmphen – 4,7-dimethyl-1,10-phenanthroline, have been synthesized and characterized by elemental analysis, IR spectroscopy, cyclic voltammetry and powder X-ray diffraction. Single‐crystal X‐ray diffraction analysis was carried out to determine crystal structures of complexes. The UV-vis spectroscopy has been applied to show the stability of the compounds in solution. The effect of the compounds on viability of HepG2 and Hep-2 cell lines has been investigated. Complex [Mn(dmphen)2L2] was found to be the most cytotoxic with IC50 values of 5.7 ± 0.6 µM (HepG2 cells) and 8.1 ± 1.2 µM (Hep-2 cells). The antimicrobial activity of complexes and ligands has been investigated against E. coli, S. aureus, P. italicum and C. steinii. All complexes have shown protistocidal activity against C. steinii. Complexes have been found to exhibit antioxidant activity measured spectrophotometrically using ABTS•+ radical.

Cu(II), Co(II), Mn(II) Complexes with 5-Phenyltetrazole and Polypyridyl Ligands: Synthesis, Characterization and Evaluation of the Cytotoxicity and Antimicrobial Activity

In this work, six new mixed-ligand Cu(II), Co(II), Mn(II) complexes with 5-phenyltetrazole (HL) and polypyridine ligands (phen – 1,10-phenanthroline, dmbipy – 2,2’-bi-4-picoline, dmphen – 4,7-dimethyl-1,10-phenanthroline, phendione – 1,10-phenanthroline-5,6-dione), namely, [Cu(dmbipy)(L)2] (1), [Cu2(dmphen)2(L)4] (2), [Cu(phendione)(L)2] (3), [Co3(phen)2(L)6] (4), [Mn3(phen)2(L)4(OAc)2] (5), [Mn(H2O)4(phen)]·phen·L2 (6), are reported. Complexes have been characterized by EPR and IR-spectroscopy, elemental, thermogravimetric and powder X-ray diffraction analysis. Molecular structures of [Cu(dmphen)2L]·L·6H2O (2a), [Co3(phen)2(HL)2(L)4(OH)2]·1.9EtOH·1.1DMSO (4a), [Mn3(phen)2(L)4(OAc)2]·H2O (5∙H2O ) and [Mn(H2O)4(phen)]·phen·L2 (6) have been determined by single crystal X–ray diffraction. The UV-vis spectroscopy has been applied to study the behavior of the compounds in solution. All complexes have been screened in vitro for their cytotoxic activity against human cancer cell lines: larynx carcinoma (Hep2), hepatocellular carcinoma (HepG2) and breast adenocarcinoma (MCF-7). Cu(II) complexes exhibit significant dose-dependent cytotoxic effect: [Cu2(dmphen)2(L)4] (2), [Cu(phendione)(L)2] (3) are found to be the most cytotoxic. The antimicrobial activity of complexes and ligands has been investigated against Escherichia coli, Staphylococcus aureus, Penicillium italicum and Colpoda steinii.

Synthesis of Co(II) and Ni(II) Asymmetric Tetraazamacrocyclic Complexes and Their Electrochemical and Antimicrobial Studies

In this work, the synthesis of two asymmetric Co(II) and Ni(II) tetraazamacrocyclic complexes has been carried out by the template method. The synthesized complexes have been characterized by various analytical techniques such as elemental analysis, UV-Vis, IR, and Mass spectroscopy. The mass spectral studies of the complexes have been found to agree with theoretically calculated values. The calculated molar conductance values for the two complexes suggest a non-electrolytic nature of the complexes. A distorted octahedral geometry has been assigned to both the complexes as shown by spectral studies. Results of the electrochemical studies of the complexes through cyclic voltammetry indicate that metal centers can be differentiated by their intrinsic redox systems, viz. Co(III)/Co(II), Co(II)/Co(I) and Ni(II)/Ni(I). Moreover, antimicrobial activities of complexes have been investigated against E. coli, S. aureus, B. subtilis, and P. aeruginosa pathogens. The results of these studies indicate that both the complexes exhibit significant antimicrobial activity against the tested pathogens.

Synthesis, characterization and antibacterial activity of [Zn(formato)2(4,4′-bipy)] complex

Zn-based MOFs, [Zn(formato)2(4,4′-bipy)] (4,4′-bipy = 4,4′-bipyridine) (1), had been successfully synthesized and characterized by elemental analysis (CHN), single crystal X-ray analysis and Single crystal X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). Then, the antimicrobial activities of complex 1 against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were evaluated by measuring growth inhibition curves and the zones of inhibition. The experimental data showed that 1 exhibited superior antibacterial activities in comparison with the zinc ion and the formic acid ligand as well as the 4,4′-bipy ligand, and the mechanism of action might be associated with the generation of reactive oxygen species (ROS).

Syntheses, structure, Hirshfeld analysis and antimicrobial activity of four new Co(II) complexes with s-triazine-based pincer ligand

The [Co(BPMT)(H2O)2Cl]Cl; (1), [Co(BPMT)(H2O)3](ClO4)2·H2O; (2), [Co(BPMT)(NO3)2]; (3) and [Co(BPMT)(H2O)3](NO3)2·H2O; (4) pincer complexes of 2,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine, (BPMT) ligand were synthesized by self-assembly technique in methanol as solvent. In all complexes, the BPMT acting as a tridentate N-donor pincer ligand. The Co(II) is hexa-coordinated in complexes 1, 2 and 4 with distorted octahedral coordination geometry while 3 has a rare hepta-coordinated Co(II) comprised a CoN3O4 coordination sphere with two bidentate nitrate ions as ligand. In 1, the most important contacts are the Cl…H (16.5%) and O…H (9.8%) interactions. For complexes 2–4, the O…H and C…O (anion-π stacking) contacts are the most important. The percentages of O…H contacts are 40.2, 39.2–37.2 and 36.4% in complexes 2–4, respectively while the percentages of C…O (anion-π stacking) contacts are 2.8, 3.2–3.7 and 2.5%, respectively. The natural charge populations of the cobalt central metal ion (Co(II)) are decreased to 0.891, 0.948, 0.950–0.953 and 0.951 e due to the interactions with the ligand groups coordinating it. The antimicrobial activity of complexes 1–3 were evaluated and compared with some commercial antibiotics. Complex 1 has better antimicrobial activity against all microbes compared to complexes 2 and 3. Also, 1 and 2 performed better than Amoxicillin, Tetracycline and Ampicillin antibiotics against E. coli and C. albicans.

Antimicrobial Activity of Silver Camphorimine Complexes against Candida Strains.

Hydroxide [Ag(OH)L] (L = IVL, VL, VIL, VIIL), oxide [{AgL}2}(μ-O)] (L = IL, IIL, IIIL, VL, VIL) or chloride [AgIIL]Cl, [Ag(VIL)2]Cl complexes were obtained from reactions of mono- or bicamphorimine derivatives with Ag(OAc) or AgCl. The new complexes were characterized by spectroscopic (NMR, FTIR) and elemental analysis. X-ray photoelectron spectroscopy (XPS), ESI mass spectra and conductivity measurements were undertaken to corroborate formulations. The antimicrobial activity of complexes and some ligands were evaluated towards Candida albicans and Candida glabrata, and strains of the bacterial species Escherichia coli, Burkholderia contaminans, Pseudomonas aeruginosa and Staphylococcus aureus based on the Minimum Inhibitory Concentrations (MIC). Complexes displayed very high activity against the Candida species studied with the lowest MIC values (3.9 µg/mL) being observed for complexes 9 and 10A against C. albicans. A significant feature of these redesigned complexes is their ability to sensitize C. albicans, a trait that was not found for the previously investigated [Ag(NO3)L] complexes. The MIC values of the complexes towards bacteria were in the range of those of [Ag(NO3)L] and well above those of the precursors Ag(OAc) or AgCl. The activity of the complexes towards normal fibroblasts V79 was evaluated by the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay. Results showed that the complexes have a significant cytotoxicity.

Low-dimensional compounds containing bioactive ligands. Part XI: Synthesis, structures, spectra, in vitro anti-tumor and antimicrobial activities of 3d metal complexes with 8-hydroxyquinoline-5-sulfonic acid

Five 3d metal [M(H2O)2(SQ)]n complexes, where M is Mn (1), Co (2), Ni (3), Zn (4) and Cu (5), and SQ is the dianion of 8-hydroxyquinoline-5-sulfonic acid have been prepared and characterized by IR spectroscopy and elemental analysis. X-ray structure analysis of 1 and 5 in combination with IR spectroscopy of all five complexes showed that complexes 1–4 are isostructural 2D polymers, while 5 is 1D polymer due to the different bonding character of SQ. Stability of all complexes in DMSO was proved by UV–Vis spectroscopy and for 4 also verified by 1H and 13C NMR spectroscopy. Cytotoxic activity tests against cervical carcinoma HeLa, colon carcinoma HCT116 and normal human fibroblast MRC-5 cell lines showed moderate but selective cytotoxicity of all complexes. Complex 1 exhibited highest activity with IC50 = 39.1 and 33.4 µM, respectively, but is lower than activity of cisplatin (CP) which IC50 = 24.3 and 14.3 µM, respectively. However, their cytotoxic activity against healthy MRC-5 cells (IC50 > 92 µM) is much lower than CP (IC50 = 19.7 µM). Antimicrobial activity of all complexes against 9 strains of pathogenic bacteria, five mould species and two yeast species is negligible.

Synthesis, spectroscopic studies, DFT calculations, cytotoxicity and antimicrobial activity of some metal complexes with ofloxacin and 2,2′-bipyridine

Five new mixed ligand metal complexes were synthesized by the reaction of Zn(II), Zr(IV), Ce(III), Th(IV) and U(VI) with ofloxacin (HOfl) and 2,2′-bipyridine (Bipy) in presence of NaOH with 1:1:1:1 M ratio. The chelation possibility of the HOfl and Bipy towards metal ions has been proposed in the light of elemental analysis, molar conductance, spectral (mass, IR, UV–Vis. and 1H NMR), magnetic and thermal studies. Infrared spectra suggest that ligands interact with metal ions as bidentate. Electronic and magnetic data proposed the octahedral structure for all complexes. The experimental studies were complemented by quantum chemical calculation. DFT calculations were carried out and ΔE for compounds in LUMO and HOMO was evaluated and indicated that the U(VI) complex with small energy gap value ΔE (0.168eV), is more reactive than all complexes. The antimicrobial activity of the complexes against various microorganisms was tested and the in vitro anticancer activity against breast (MFC7) and Colon (HCT-116) cell lines was also screened.

Thermal, spectral and biological investigation of new nickel complexes with imidazole derivatives

Four new Ni(II) complexes with acrylate and imidazole (Him) or imidazole derivatives [2-methylimidazole(2-MeIm)/5-methylimidazole(5-MeIm)/2-ethylimidazole(2-EtIm)] as ligands were prepared and characterized. All coordination compounds were characterized by elemental analysis, infrared (FTIR) and ultraviolet-visible-near-infrared (UV-Vis-NIR) spectroscopy, mass spectroscopy, magnetic moments measurements and thermal analysis (TG). The resulted complexes were formulated as follows: [Ni(HIm)2(acr)2] (1), [Ni(2-MeIm)2(acr)2(H2O)]·H2O (2), [Ni(5-MeIm)2(acr)2]·H2O· (3), [Ni(2-EtIm)2(acr)2(H2O)]·H2O (4). On the basis of magnetic moments measurements and on UV–Vis–NIR spectra, for all Ni(II) complexes was proposed an octahedral stereochemistry. Acrylate ions act as bidentate in complexes (1) and (3); meanwhile, in (2) and (4) they behave as bidentate and unidentate. Antimicrobial activity of complexes was investigated on ATCC reference and clinical microbial strains. The MIC (minimum inhibitory concentration) values revealed moderate antimicrobial activity of complex (1) against Enterococcus faecium and of complex (2) against Pseudomonas aeruginosa and Bacillus subtilis.

Synthesis, characterization, antiproliferative, and antimicrobial activity of osmium(II) half-sandwich complexes

New osmium(II)-arene complexes [(η6-C6H6)OsCl(C5H4N-2-CH=N-C6H5X)](PF6) (X = p-flouro (1), p-chloro (2), p-methyl (3)) were synthesized by reaction of the corresponding bidentate N,N′-ligands with the osmium-arene precursor [(η6-C6H6)Os(μ-Cl)Cl]2 in a 2:1 ratio. These complexes were characterized by UV–Vis, IR, 1H, 13C NMR spectroscopy, and elemental analysis and, for compound 1, a single crystal X-ray structure was also obtained. The complexes were investigated for antiproliferative activity in vitro against MCF-7 (human breast adenocarcinoma), Caco-2 (human epithelial colorectal adenocarcinoma), and HepG2 (human hepatocellular carcinoma) tumor cell lines. To test their selectivity, the non-tumor HEK293 (human embryonic kidney) cell line was used. The compounds were selective toward the tumor cell lines when compared to the known anticancer drug 5-fluorouracil which displayed low selectivity. The compounds were substantially more active against Caco-2 than 5-fluorouracil. They also showed moderate activity against the other two tumor cell lines. In addition, the antimicrobial activity of complex 2 was explored against a panel of antimicrobial-susceptible and -resistant Gram-negative and Gram-positive bacteria. Complex 2 showed anti-mycobacterial activity against Mycobacterium smegmatis and bactericidal activity against drug-resistant Enterococcus faecalis and methicillin-resistant Staphylococcus aureus ATCC 43300.