Examples of Lung Toxicants Requiring Activation

The activation of pulmonary toxicants falls into three main categories or mechanisms, depending either on the site of formation of the activated compound or on the nature of the reactive intermediate. 

The parent compound may be activated in the liver, with the reactive metabolite then transported by the circulation to the lung. As would be expected, the activated compounds may lead to covalent binding and damage to both liver and lung tissue. 

Another means of metabolic activation is the cyclic reduction/oxidation of the parent compound, resulting in high rates of consumption of NADPH and production of superoxide anion. Either the depletion of NADPH and/or the formation of reactive oxygen radicals could lead to cellular injury. 

The following three chemicals serve to illustrate these three mechanisms of activation. 

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