Synthesis, characterization and antimicrobial activity of Fe(II), Zn(II), Cd(II) and Hg(II) complexes with 2,6-bis(benzimidazol-2-yl) pyridine ligand.

2,6-Bis(benzimidazol-2-yl)pyridine (L) ligand and complexes [M(L)Cl(2)] and [Fe(L)(2)](ClO(4))(2) (M=Zn, Cd, Hg) have been synthesized. The geometries of the [M(L)Cl(2)] complexes were derived from theoretical calculation in DGauss/DFT level (DZVP basis set) on CACHE. The central M(II) ion is penta-coordinated and surrounded by N(3)Cl(2) environment, adopting a distorted trigonal bipyramidal geometry. The ligand is tridentate, via three nitrogen atoms to metal centre and two chloride ions lie on each side of the distorted benzimidazole ring. In the [Fe(L)(2)](ClO(4))(2) complex, the central Fe(II) ion is surrounded by two (3N) units, adopting a octahedral geometry. The elemental analysis, molecular conductivity, FT-Raman, FT-IR (mid-, far-IR), (1)H, and (13)C NMR were reported. The antimicrobial activities of the free ligand, its hydrochloride salt, and the complexes were evaluated using the disk diffusion method in dimethyl sulfoxide (DMSO) as well as the minimal inhibitory concentration (MIC) dilution method, against 10 bacteria and the results compared with that for gentamycin. Antifungal activities were reported for Candida albicans, Kluyveromyces fragilis, Rhodotorula rubra, Debaryomyces hansenii, Hanseniaspora guilliermondii, and the results were referenced against nystatin, ketaconazole, and clotrimazole antifungal agents. In most cases, the compounds tested showed broad-spectrum (Gram positive and Gram negative bacteria) activities that were either more effective than or as potent as the references. The binding of two most biologically effective compounds of zinc and mercury to calf thymus DNA has also been investigated by absorption spectra.

Susceptibilities of Mycobacterium leprae and M. avium complex to the H2O2-Fe-mediated halogenation system supplemented with antimicrobial agents.

The susceptibilities of Mycobacterium leprae and M. avium complex (MAC) to the H2-O2-Fe-mediated halogenation system supplemented with antimicrobial agents were evaluated by fluorescein diacetate-ethidium bromide (FDA/EB) staining. In the case of M. leprae, the number of greenstained bacteria (intact cells) was reduced in the presence of the H2O2-Fe-mediated halogenation system supplemented with agents possessing antileprosy activity, such as rifampin, 4,4'-diaminodiphenylsulfone (dapsone), clofazimine, and ofloxacin. In the case of the MAC strain, although viable units of the organisms were reduced by the halogenation system alone, the number of greenstained cells in the FDA/EB stain was not reduced, even when the halogenation system was used in combination with ofloxacin. Because stainability of the cells is related to structural and functional intactness of the membrane, differences between M. leprae and the MAC strain imply possible differences in the rigidity of the cell membrane.

Oxygen metabolism in phagocytes of leprotic patients: enhanced endogenous superoxide dismutase activity and hydroxyl radical generation by clofazimine.

We examined the generation of active oxygens (O2-, H2O2, and OH X ) and the superoxide dismutase (SOD) activity of polymorphonuclear leukocytes (PMNs) and monocytes from 14 leprotic patients manifesting a bacillary index above 2.2. Patients with disease of more than 4 years in duration showed significantly enhanced SOD activity and a decrease in O2- and OH X production. The antileprotic agent, clofazimine, significantly increased the generation of OH X in a dose-dependent manner, with a subsequent decrease in H2O2, but had no effect on the SOD activity of the PMNs and monocytes. In medium containing FeSO4 or Fe2+-EDTA, the drug elevated OH X production markedly further. Phagocytic SOD in PMNs and monocytes of leprotic patients was both host and bacillus derived, because the presence of cyanide, to which human-derived cuprozinc SOD is susceptible, did not completely abrogate SOD activity. The difficulty in treating leprosy may be partly ascribable to decreased phagocytic OH X generation, which in leprosy patients is apparently due to the uptake of Hansen bacillus-derived SOD. Clofazimine may be effective in leprosy by chelating Fe2+, with the resultant potentiation of the catalyzing activity of Fe2+ in the Haber-Weiss reaction increasing OH X formation from H2O2.