The CANCER RISK of BENZO[α] PYRENE

Abstract # 30

Presented by My Linh Tran

Math and Science DivisionSan Jose City College

Spring 2006

Instructor Dr. Adamczeski,Madeline

ABSTRACT

When people eat burnt barbequed food, they may carelessly consume significant amounts of carcinogens, some of which called aromatic hydrocarbons. The definition of aromatic hydrocarbon can be extended from simple one ring to substances that have two or more benzene-like rings joined together by common bonds (e.g. polycyclic aromatic hydrocarbons). Benzopyrene (BaP) is categorized as a polycyclic aromatic hydrocarbon and is recognized as one of the most carcinogenic of the group. BaP is formed from a reaction between one of the twenty essential amino acids and creatine in the process of cooking meats at high temperature. Creatine is an amino acid that does not occur in protein but is found in the muscle tissues of vertebrates both in the free form and as phosphocreatine (e.g. it supplies energy for muscle contraction). After eating BaP, our body attempts to rid of the foreign substance by converting it into a water-soluble compound for metabolism, a diol expoxide. This compound, in turn, reacts with and binds to cellular DNA. Consequently, diol expoxide alters DNA and mutates genes. This presentation introduces BaP, shows reaction mechanism involving BaP, and explains how BaP can cause cancer.

Benzopyrene- Polycyclic Aromatic Hydrocarbons and Mutations

• Seminar Outline• Introduction: • What is Benzopyrene? • Burnt barbeque, meat, fish,• How is it made?• Where can we find it • Structure • C20H12• Toxicity data research• Epoxidation• Chemical evaluation• Properties: • Benzene• Flat, sp2, conjugated pi electrons• Stable• Reacts with oxygen and other electrophiles• Biological evaluation• Metabolism:• Liver MFO enzyme• Water-soluble epoxy groups • Reactions with epoxy groups• Epoxides of benzopyrene• DNA mutation• It becomes similar to dA and dG• General information• Dose • Duration• Pathway• Individual• VI. Conclusion • The dose makes the poison• BBQ at low temperature• Use thinner slice of meat• Teriyaki sauce or turmeric-garlic sauce before barbeque

SUMMER BARBEQUE

WOULD YOU EAT THIS?

The well known Polycyclic Aromatic Hydrocarbon

OVERVIEW

• Introduction• What is Benzo[α]pyrene?• Chemical properties• What is its effect on

humans?• How is it made?• Where can we find it?• Prevention

BENZO[α]PERENE (BaP)

•Yellow crystals or Powder•Molecular formula: C20H12•Formula weight: 252.31 amu•CAS No: 50-32-8•Boiling point: 495 oC•Melting point: 176 oC

•RAT LD50 50mg / kg•MOUSE LDLO 500mg / kg•FROG LDLO 11 mg/kg

BARBEQUE and POLYCYCLIC and CANCER

• SOURCE: BURNT Barbeque

• EFFECT: Formed from a reaction between amino acids and creatine when meats are cooked at high temperature

• Creatine: an amino acid that does not occur in proteins but is found in the muscle tissue of vertebrates both in the free form and as phosphocreatine; supplies energy for muscle contraction

• CONSEQUENCE: MUTATION

• After eating or inhaling, body attempts to rid itself of the foreign substance by converting it into a water-soluble metabolism: DIOL EXPOXIDE

• DIOL EXPOXIDE Metabolite reacts with & binds to cellular DNA

• DIOL EXPOXIDE altering the DNA & leading to mutations or cancers

HOW BaP CAUSE MUTATIONS?

STABILITY OF BaP

• Stable, incompatible with strong oxidizing agents

• Causes oxidation, gain one or more electrons, undergoes reduction, oxidation number of atom decrease

• PERCHLORATES• PEROXIDES• PERMANGANATES• CHLORATES• NITRATES• CHLORINE• BROMINE• FLOURINE

BaP- SITE of EPOXIDATION

http://www.nyu.edu/projects/geacintov/images/WEB_Figures/WEB_PAH2.jpg

SIMILAR to the BASES THEY REPLACE

HYDROLYSIS of EPOXIDE

(R,S,S,R) enantiomer:

On reaction with DNA, DE derived (BaP) are largely selective for G adduct formation

DIOL EPOXIDE HYDROLASE

DIOL EPOXIDE

DNA- DIOL EPOXIDE

• Altered DNA by replication• Altered RNA by transcription• Incorrect protein synthesis• Shortened DNA by replication through blockage• Shortened RNA by transcription blockage

HOW ARE WE EXPOSED TO BaP?

• Breathing air contaminated by smoke from incomplete combustion & vehicle exhaust

• Eating meats and fish that have been smokes or charbroiled

• Smoking tobacco products

WHERE BaP CAN BE FOUND?

• Wildfires and Control burning• Combustion engine vehicles• Charbroiled meat • Burning or scrap tires

Very toxic in the environment- may cause long-term damageBaP is not produced commercially in the United States except as research chemicalBaP has decreased it emission over last 13 yearsEmissions from Prodtion Processes have reduced greatest

BaP ENVIRONMENTAL INFORMATION

PREVENTIONS

• Barbecue meat at low temperatures, do not overcook

• Use thinner slices of meat (they cook faster and with less heat)

• Turn the meat more frequently • Teriyaki sauce or turmeric-garlic sauce before

barbeque

• Marinade before grilling

VISITED WEBSITES

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