Benzopyrene

Benzopyrene
Chemical name	Benzo[a]pyrene
Chemical formula	C20H12
Molecular mass	252.31 g/mol
CAS number	[50-32-8]
Density	1.24 g/cm3
Melting point	179 °C
Boiling point	495 °C
SMILES	C1\C=C2\C=C/Cc3ccc4cc5ccccc5c1c4c23

Benzopyrene, C₂₀H₁₂, is a five-ring polycyclic aromatic hydrocarbon that is mutagenic and highly carcinogenic. It is a crystalline yellow solid. Benzopyrene is a product of incomplete combustion at temperatures between 300 and 600°C. Is found in coal tar, in automobile exhaust fumes (especially from diesel engines), tobacco smoke, and in charbroiled food. Recent studies have revealed that levels of benzopyrene in burnt toast are significantly higher than once thought.

Consequences of Benzopyrene

Researchers at Kansas State University recently discovered a link between vitamin A and emphysema in smokers. Benzopyrene was found to be the link to the deficiency, since it induces vitamin A deficiency in rats.

Chemical structure of benzo-[a]-pyrene

On October 18, 1996, a study was published that provided the first true molecular evidence conclusively linking components in tobacco smoking to lung cancer. A chemical found in tobacco smoking, benzopyrene, was shown to cause genetic damage in lung cells that is identical to the damage observed in the DNA of most malignant lung tumours.

A 2001 National Cancer Institute study found levels of benzopyrene to be significantly higher in foods that were cooked well-done on the barbecue, particularly steaks, chicken with skin, and hamburgers. Japanese scientists showed that cooked beef contains mutagens, chemicals that are capable of altering the chemical structure of DNA.

Interaction with DNA

Chemical structure of the carcinogen benzopyrene diol epoxide

Benzopyrene diol epoxide ((+)-7R,8S-dihydroxy-9S,10R-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene) is a product of cytochrome P450 oxidation of benzopyrene. This molecule intercalates in DNA, covalently modifying the guanine nucleobases through the epoxide functionality. This can disrupt the normal process of copying DNA, and may lead to cancer. This mechanism of action is similar to that of aflatoxin.

References

• "Benzopyrene and Vitamin A deficiency". Researcher links cigarettes, vitamin A and emphysema. URL accessed on March 5, 2005.
• "Benzopyrene in Barbeque". Newhouse A1. URL accessed on March 5, 2005.
• "Lung cancer as consecuence by Benzopyrene in smokers". Lung Cancer. URL accessed on March 5, 2005.
• "Levels of Benzopyrene in Burnt toasts". Guardian Unlimited. URL accessed on March 5, 2005.
• "DNA interaction with Benzopyrene". DNA. URL accessed on March 5, 2005.

See also

• Benzene
• Pyrene, a four-ring analog.

This article about an organic compound is a . You can Wikipedia by expanding it.