Heterocyclic Amines (HCA)

Heterocyclic amines (HCAs) contain at least one heterocyclic ring (with atoms of at least 2 different elements) and one amine group, attached to the heterocyclic ring. Major groups of HCAs are beta-Carbolines, Pyrrolidines, Pyrroles (in Hb and vitamin B12), Pyridines (vitamin B3 and B6) and Pyrimidines (vitamin B1), including Purines (adenine, guanine).

Many HCA are harmless, or even beneficial (eg vitamins), whereas others, created by cooking or burning, may cause cancer.

HCA in cigarette smoke

The following HCA are a few of the HCA found in cigarette smoke: Trp-P-1 (12), Trp-P-2 (14), 4-aminobiphenyl (16), MeIQx (12) and Glu-P-1 (19)

But exactly the same HCA are also found in cooked foods: Trp-P-1 (13), Trp-P-2 (15), 4-aminobiphenyl (17), MeIQx (18) and Glu-P-1 (20)

Carcinogenic HCA in cooked food

HCAs form when amino acids and creatine react at high cooking temperatures.

• 2-amino-3-methylimidazo[4,5-f]quinoline (IQ; in broiled sardines, cooked beef) [1]
• 2-amino-3,4-dimethylimidazo[4,5-f]quinoline [2][3]
• 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx; in various cooked foods) [4]
• 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP; in cooked meat and fish) [5][6]

Mutagenic HCA in cooked foods

• 2-amino-1-methyl-6-(4-hydroxyphenyl)imidazo[4,5-b]pyridine (4'-OH-PhIP; in broiled beef) [7] (creatine + tyrosine + glucose)
• 2-amino-4-hydroxymethyl-3,8-dimethylimidazo[4,5-g]quinoxaline (4-CH2OH-8-MeIQx; in beef extract) [8]
• 2-amino-1,7,9-trimethylimidazo[4,5-g]quinoxaline (7,9-DiMeIgQx++ +; in beef extract) [9]

• 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1)
• 2-aminodipyrido[1,2-a:3',2'-d]imidazole (Glu-P-2)
• 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1)
• 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2)
• 2-amino-9H-pyrido[2,3-b]indole (A alpha C)
• 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeA alpha C)