Bacteria Chelating agents, antibacterial

Because parasites are dependent on the host cell for nutrients and essential components, the arguments mentioned previously for alteration of the optimal metal concentration and its application to antibacterial and antiviral therapy are equally valid in the case of parasites. The sequestration of zinc and subsequent biochemical effects may present an example of this and the behaviour is somewhat reminiscent of the early and classic demonstration of the mode of action of 8-hydroxyquinoline (oxine). This reagent is also trypanocidal and, as with bacterial systems, cobalt protects against the lethal action [88]. The mode of action of oxine is presumably the same as for bacteria (see Chapter 9). Other chelating agents studied in... 

Chelating agents may manifest their antiviral activity by metal sequestration and, as with bacteria and parasites, the natural differences between the host and invading cells may be exploited. Chelating agents with antiviral activity include the thiosemicarbazones, 1,10-phenanthrolines and phosphonoacetates. The latter compounds may act by zinc chelation. Metal complexes with antiviral action are platinum and palladium amines, as well as the antibacterial silver and mercury species. 

Microbes acquire iron by utilizing very specific, low molecular weight iron chelators called siderophores. The resistance of bacteria to previously effective antibiotics can be circumvented in part by covalent coupling of antibiotics to siderophores. Some synthetic siderophores have been found to possess significant antibacterial activity themselves. They have also been found to have considerable potential as nontoxic, organ selective MRI contrast agents (27). 

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