J.R. Anacona

Metal complexes of the flavonoid quercetin: antibacterial properties

Two types of complexes were obtained when quercetin (L) was reacted with metal ions in EtOH. The compounds [M(L)Cl2(H2O)2] (M = MnII or CoII) and the semi-oxidized complexes [M(L)2CL2] · 2H2O (M = CdII or HgII) were characterized by elemental analysis., conductivity and magnetic susceptibility measurements, i.r., u.v.–vis. and e.p.r. spectroscopy. The ν(C=O) stretching mode located on the C ring of the ligand and the complexes remains in the same range, showing that this oxygen atom does not participate in coordination to the metal ions. Magnetic susceptibilities and e.p.r. spectra of powdered samples indicated that the monomeric form of the complexes in the solid state, and the paramagnetic nature of the CdII and HgII complexes is attributable to the semiquinone character of the ligand. The antibacterial activity of the metal complexes were tested against five bacterial strains and compared with penicillin activity.

Synthesis and antibacterial activity of metal complexes of ciprofloxacin

The interactions of ciprofloxacin (HCipro) with transition metals have been investigated. Two types of complexes, [M(Cipro)(OAc)(H2O)2] · 3H2O (M = MnII, CoII, CuII or CdII) and [M(Cipro)(OAc)] · 6H2O (M = NiII or ZnII), were obtained and characterized by physicochemical and spectroscopic methods. The i.r. spectra of the complexes suggest that the ciprofloxacin behaves as a monoanionic bidentate ligand. In vitro antibacterial activities of the HCipro and the complexes were tested.

Synthesis, characterization and antibacterial activity of a Schiff base derived from cephalexin and sulphathiazole and its transition metal complexes.

Metal(II) coordination compounds of a cephalexin Schiff base (HL) derived from the condensation of cephalexin antibiotic with sulphathiazole were synthesized. The Schiff base ligand, mononuclear [ML(OAc)(H2O)2] (M(II)=Mn, Co, Ni, Zn) complexes and magnetically diluted trinuclear copper(II) complex [Cu3L(OH)5] were characterized by several techniques, including elemental and thermal analysis, molar conductance and magnetic susceptibility measurements, electronic, FT-IR, EPR and (1)H NMR spectral studies. The analytical and molar conductance values indicated that the acetate ions coordinate to the metal ions. The Schiff base ligand HL behaves as a monoanionic tridentate NNO and tetradentate NNOO chelating agent in the mono and trinuclear complexes respectively.

Manganese(II) and palladium(II) complexes containing a new macrocyclic Schiff base ligand: antibacterial properties

Complexes of tetradentate macrocyclic Schiff base ligand, L, with MnII and PdII ions have been synthesized by the template condensation of 1,10-phenanthroline-2, 9-dicarboxaldehyde, 2,3-diamino-1,4-naphthoquinone and 1,2-dibromoethane in EtOH. The complexes were characterized by physicochemical and spectroscopic methods and an octahedral geometry is suggested for their structure. They have been screened for antibacterial activity against several bacteria, and the results are compared with the activity of penicillin.

Synthesis and antibacterial activity of metal complexes of cefazolin

Cefazolin (Hcefaz) interacts with transition metal(II) ions to give [M(cefaz)Cl] complexes (M = MnII, CoII, NiII, CuII, ZnII, PdII) and [Ag2(cefaz)2Cl2] which were characterized by physicochemical and spectroscopic methods. Their i.r. and the 1H-n.m.r. spectra suggest that cefazolin behaves as a monoanionic tetradentate ligand. The complexes have been screened for antibacterial activity and the results are compared with the activity of cefazolin.

SYNTHESIS AND ANTIBACTERIAL ACTIVITY OF SOME METAL COMPLEXES OF BETA-LACTAMIC ANTIBIOTICS

Abstract An overview of the results of the interaction of β-lactamic antibiotics with some transition metal ions is given. Several complexes have been synthesized and characterized by physicochemical and spectroscopic methods. Some exhibit very promising antibacterial activity. Clavulanic acid (L1), penicillin (L2), ampicillin (L3), cephalexin (L4), cefazolin (L5) and cephalothin (L6) were allowed to react with metal ions in methanol under nitrogen. IR spectra of clavulanic acid, penicillin and ampicillin complexes showed strong modifications of the carbonyl group located on the lactamic ring, indicating that this oxygen participates in the coordination to the metal ions along with the carboxylate group. Thus L1 and L2 behave as monoanionic bidentate ligands while L3 behaves as a monoanionic tridentate ligand. The IR spectra of cephalexin, cefazolin and cephalotin chelates show that the beta lactamic carbonyl group does not participate in coordination to the metal ions. A relationship between the structure of the complexes and their antibacterial activity can be observed. In vitro antibacterial activity of the antibiotics and the complexes were tested using the filter paper diffusion method and the chosen strains include Escherichia coli ATCC 10536, Pseudomonas aeruginosa ATCC 9027, Salmonella typhimorium ATCC 14028, Staphylococcus aureus ATCC 6538, Bacillus cereus ATCC 9634, Proteus mirabilis 35659, Proteus vulgaris ATCC 9920, Klebsiella pneumoniae ATCC 10031, Salmonella sp, Shigella sp ATCC 11126, Streptococcus viridans and Salmonella enteritidis ATCC 497.

Synthesis, characterization and antibacterial activity of a tridentate Schiff base derived from cephalothin and sulfadiazine, and its transition metal complexes

Metal(II) coordination compounds of a cephalothin Schiff base (H2L) derived from the condensation of cephalothin antibiotic with sulfadiazine were synthesized. The Schiff base ligand, mononuclear [ML(H2O)3] (M(II)=Mn,Co,Ni,Zn) complexes and magnetically diluted dinuclear copper(II) complex [CuL(H2O)3]2 were characterized by several techniques, including elemental and thermal analysis, molar conductance and magnetic susceptibility measurements, electronic, FT-IR, EPR and (1)H NMR spectral studies. The cephalothin Schiff base ligand H2L behaves as a dianionic tridentate NOO chelating agent. The biological applications of complexes have been studied on two bacteria strains (Escherichia coli and Staphylococcus aureus) by agar diffusion disc method.

SYNTHESIS AND CHARACTERIZATION OF METAL COMPLEXES WITH PENICILLIN

Abstract The reaction of Ni(II), Zn(II), Cd(II), Fe(III) and La(III) ions with sodium penicillinate at room temperature has allowed the isolation of two types of complexes with the following general formulae: M(pen)2 · nH2O (M = Ni(II), Zn(II), Cd(II); n = 3,4) and M(pen)2 · Cl · nH2O (M = Fe(III), La(III); n = 2). The complexes were characterized by physjcochemical and spectroscopic methods. A monomeric structure is proposed with octahedrally coordinated metals ions. The divalent ions are coordinated through the amide and β-lactam carbonyls and a car-boxylate group from penicillin while the trivalent ions are coordinated through the carboxylate group and the amide carbonyl only.

SYNTHESIS AND CHARACTERIZATION OF METAL COMPLEXES WITH AMPICILLIN

Abstract The reaction, in water, of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) ions with sodium ampicillinate at room temperature has allowed isolation of dimers with the following general formula [M(amp)Cl]2 × nH2O (n = 1.5−3.2). The complexes were characterized by elemental analyses, conductivity measurements, magnetic susceptibilities and spectroscopic methods (IR, Raman, EPR and UV-Visible). A dinuclear structure based on octahedrally coordinated metal ions is proposed.

Synthesis and antibacterial activity of cephradine metal complexes

Cephradine (Hcephra) interacts with transition metal ions to give [Fe(cephra)Cl2] and [M(cephra)Cl] complexes (M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)) which were characterized by physicochemical and spectroscopic methods; a tetrahedral geometry is suggested for their structures where cephradine behaves as monoanionic tridentate ligand. The complexes have been screened for antibacterial activity against several bacteria, and the results showed that all metal complexes tested had lower antibiotic activity than the free ligand.