Benzopyrene

A benzopyrene is an organic compound with the formula C20H12. Structurally spoken, the colourless isomers of benzopyrene are pentacyclic hydrocarbons and are fusion products of pyrene and a phenylene group. Two isomeric species of benzopyrene are benzo[a]pyrene and the less common benzo[e]pyrene. They belong to the chemical class of polycyclic aromatic hydrocarbons.

Related compounds include cyclopentapyrenes, dibenzopyrenes, indenopyrenes and naphthopyrenes. Benzopyrene is a component of pitch and occurs together with other related pentacyclic aromatic species such as picene, benzofluoranthenes, and perylene. Moreover, they can be found in coal tar (after a forest fire), after eruption of volcanoes, in cigarette smoke, wood smoke, and in burnt foods such as coffee. Especially fumes that develop from fat dripping on blistering charcoal are rich in benzopyrene, which can condense on barbecued goods.

Benzopyrenes are problematic because they intercalate into DNA, interfering with transcription. They are considered pollutants and carcinogens. Especially the mechanism of action of benzo(a)pyrene-related DNA modification is well investigated and relates to the activity of cytochrome P450 subclass 1A1 (CYP1A1).Seemingly, the high activity of CYP1A1 in the intestinal mucosa prevents major amounts of ingested benzo(a)pyrene to enter portal blood and systemic circulation. The intestinal (but not hepatic) detoxification mechanism seems to depend on receptors that recognize bacterial surface components (TLR2).