Carcinogens-Environment

CNBY PPT 9

What is a chemical carcinogen?

A chemical that can cause cancer by altering DNA, often through forming electrophilic compounds that react with nucleophilic sites in DNA

What are DNA adducts?

Covalent attachments of chemical moieties to DNA that can cause mutations if not repaired

How can chemical carcinogens act?

Directly or by being metabolized into more carcinogenic compounds

What are Polycyclic Aromatic Hydrocarbons (PAHs)?

Carcinogens formed from burning organic substances like coal, wood, or meat fat; they can form DNA adducts

What is the most common PAH in cigarette smoke?

Benzo[a]pyrene (BP)

How do PAHs cause mutations?

They form DNA adducts, e.g., BP diol epoxides mainly cause G → T transversions

What is the role of CYP1A1 enzyme in PAH metabolism?

It metabolizes PAHs in the liver; its activity varies among individuals, affecting carcinogen exposure

What are Heterocyclic Amines (HCAs)?

Carcinogens formed when meat is cooked at high temperatures from reactions between amino acids, sugars, and creatine/creatinine

How can HCA formation be reduced?

Oven-roasting, marinating meat, or coating with breadcrumbs before frying; avoid charring

Examples of HCAs include?

Phe-P-1, IQ, and Mel Q

How do PAHs and HCAs differ in formation?

PAHs form from smoke when fat/juices drip onto fire; HCAs form from chemical reactions in meat at high heat

What are nitrosamines/nitrosamides?

Carcinogens found in tobacco and formed when nitrites react with amines in smoked/preserved meats

How do nitrosamines cause DNA damage?

By forming alkylated O6-guanine derivatives; MGMT enzyme can repair this in one step

What is Bisphenol A (BPA)?

A chemical used in polycarbonate plastics and epoxy resins, often leached into food and drinks

How does BPA affect DNA and cells?

Causes DNA methylation, reduces DNA repair proteins, and acts as an anti-estrogen disrupting hormonal function

How can BPA exposure be reduced?

Use BPA-free containers, avoid heating plastics not meant for microwaves, reduce canned food use

What role does nitric oxide (NO) play in smoked meats?

Binds myoglobin to preserve red color, forming nitrosomyoglobin