Evidence was found that the inhibitory action of Cu(DMP)2NO3, the copper(I) complex of 2,9-dimethyl-1,10-phenanthroline (DMP), on Mycoplasma gallisepticum is a consequence of the ultimate toxicity of copper, and not that of the ligand, DMP. From uptake studies with radiolabeled 67Cu and [14C]DMP, we concluded that significantly more copper than DMP is bound to the mycoplasmal cell. It appeared that dissociation of Cu(DMP)2+ occurred shortly after interaction with the cell membrane. Copper was transported across the cytoplasmic membrane. A strong dependence of copper uptake on the incubation medium was observed in the absence of DMP. The main function of the ligand DMP appeared to be as a vehicle for the transport of copper from nontoxic copper-medium complexes to membrane-buried cellular ligands.
Various physiological important activities of Mycoplasma gallisepticum were inhibited by the copper(I) complex of 2,9-dimethyl-1,10-phenanthroline [Cu(DMP) Investigations on the mode of action of the copper(I) complex of 2,9-dimethyl-1,10-phenanthroline [Cu(DMP)2NO3] on Paracoccus denitrificans have been described previously (25). Interference with the cytoplasmic membrane, resulting in inhibition of respiratory electron transport, was found to constitute the main mode of action of this copper complex.Cu(DMP)2NO3 and related copper complexes are also known to have a strong growth inhibitory effect on Mycoplasma gallisepticum (1, 2). This organism is pathogenic for fowl, in which it attacks the epithelium of the respiratory tract.There are many differences in morphology, ultrastructure, and physiology between P. denitrificans and M. gallisepticum. P. denitrificans is a nonfermentative, gram-negative bacterium. It is dependent on respiratory electron transport for the supply of energy (4)
In the course of an investigation into the synthesis and properties of 3‐aryl‐4‐hydroxycoumarins a new direct synthesis of these compounds was found. In an acid medium 4‐hydroxycoumarin can be coupled directly to a diazotized aniline to form the desired 4‐hydroxycoumarin derivative.
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