Figure 7.

Proposed catalytic cytochrome P450 cycle implicated in the toxification of 1,2-unsaturated PAs. In analogy to drugs, ethanol and other exogenous compounds, the 1,2-unsaturated PAs (UPAs) enter the catalytic cytochrome P450 cycle as substrate to be metabolized, shown on top of the cycle right side. After several steps, the metabolized UPA leaves the cycle as toxic radical DHPA•, whereby the 1,2-unsaturated PA loses its double bond and changes to pyrrole protein adducts. CYP stands for its various isoforms. As a reminder, regarding cytochrome P450, the term “P450” was used to describe a “pigment” with an absorption maximum at 450 nm within the ferrous-carbon monoxide complex of CYP in rat liver microsomes [191]. The figure was modified and retrieved from an open access report of Teschke and Danan [184].