Benzopyrene

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Chemical structure of benzo[a]pyrene
Chemical structure of benzo[e]pyrene

A benzopyrene is an organic compound with the formula C20H12. Structurally speaking, the colorless 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.[1] It is naturally emitted by forest fires and volcanic eruptions and can also be found in coal tar, cigarette smoke, wood smoke, and burnt foods such as coffee. Fumes that develop from fat dripping on blistering charcoal are rich in benzopyrene, which can condense on grilled goods.[2]

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).[3] Seemingly, the high activity of CYP1A1 in the intestinal mucosa prevents major amounts of ingested benzo(a)pyrene from entering portal blood and systemic circulation.[4] The intestinal (but not hepatic) detoxification mechanism seems to depend on receptors that recognize bacterial surface components (TLR2).[5]

Evidence exists to link benzo[a]pyrene to the formation of lung cancer.[6]

References

  1. ↑ W. D. Betts "Tar and Pitch" in Kirk‑Othmer Encyclopedia of Chemical Technology, 1997, John Wiley & Sons, New York. doi: 10.1002/0471238961.20011802052020.a01
  2. ↑ Larsson, B. K.; Sahlberg, GP; Eriksson, AT; Busk, LA (1983). "Polycyclic aromatic hydrocarbons in grilled food". J Agric Food Chem. 31 (4): 867–873. doi:10.1021/jf00118a049. PMID 6352775. 
  3. ↑ Uno, S.; Dalton, TP; Dragin, N; Curran, CP et al. (2006). "Oral Benzo[a]pyrene in Cyp1 knockout mouse lines: CYP1A1 important in detoxication, CYP1B1 metabolism required for immune damage independent of total-body burden and clearance rate". Mol Pharmacol. 69 (4): 1103–1112. doi:10.1124/mol.105.021501. PMID 16377763. 
  4. ↑ Uno, S.; Dragin, N; Miller, ML; Dalton, TP et al. (2008). "Basal and inducible CYP1 mRNA quantitation and protein localization throughout the mouse gastrointestinal tract". Free Radic Biol Med. 44 (4): 570–83. doi:10.1016/j.freeradbiomed.2007.10.044. PMC 2754765. PMID 17997381. 
  5. ↑ Do, KN; Fink, LN; Jensen, TE; Gautier, L; Parlesak, A (2012). "TLR2 controls intestinal carcinogen detoxication by CYP1A1". In Lebedeva, Irina V. PLoS ONE 7 (3): e32309. doi:10.1371/journal.pone.0032309. PMC 3307708. PMID 22442665. 
  6. ↑ Denissenko, M. F.; Pao, A.; Tang, M.-s.; Pfeifer, G. P. (1996). "Preferential Formation of Benzo[a]pyrene Adducts at Lung Cancer Mutational Hotspots in P53". Science 274 (5286): 430–2. doi:10.1126/science.274.5286.430. PMID 8832894. 
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