The Polycyclic Aromatic Hydrocarbons can easily be found in many products, such as in exhaust gases, cigarette smoke, smoked foods and grilled meat.
The molecule considered is benzopyrene. This molecule is very complex and undergoes the oxidation reaction by cytochrome P450. The result of this oxidation is the formation of epoxides at the level of a benzopyrene ring. Fortunately, the cell is able to inactivate the epoxide, thanks to a particular enzyme called epoxide hydroxide. This enzyme acts positively in our body, because by opening the epoxy ring it blocks the formation of new epoxides, which turn out to be very dangerous metabolites, as they are powerful electrophiles with a toxic, carcinogenic and teratogenic effect.
Unfortunately there is a drawback. Epoxide hydrolase is a stereospecific enzyme, so it acts on molecules that have a specific spatial conformation. If the forming metabolite has an epoxide in the TRANS position, the enzyme no longer recognizes this substrate, therefore the opening of the epoxy ring and the consequent inactivation of the epoxide no longer occurs. The active metabolite, since it is not inactivated and eliminated, remains in our body by easily binding to DNA and facilitating the onset of skin and lung cancer.
