The Influence of Oxidative Stress, Carcinogens and Cloning on DNA ...

O
O
N-OH-3-ABA
O
O
NH
NO 2
3-NBA
Nitro-reduction
NHOH
O-acetyltransferase
Or
sulfotransferase
H
N
O
O
R
Reduction
N-acetylation
R: -COCH 3 / -SO 3H
NH
Figure 12: Proposed metabolic activation pathway <strong>of</strong> 3-NBA (281)
27
Introduction
Heterocyclic aromatic amines (HAAs) represent the second equally important class <strong>of</strong> exoge-
nous DNA adducts that contribute to human cancer risk ( 290) . <strong>The</strong>y are formed in consequence
<strong>of</strong> cooking foods at high temperatures <strong>and</strong>/or for long period <strong>of</strong> time (291) , especially frying or
grilling proteinaceous foods such as meat (291, 292) , fish <strong>and</strong> poultry, as products <strong>of</strong> protein pyrolysis
(293, 294) . <strong>The</strong>y are also generated from occupational source (295) , environmental source
(296) <strong>and</strong> tobacco smoking (290, 297) . Many <strong>of</strong> these HAAs were used in laboratory experiments
as well as color additives in pharmaceutical preparations <strong>and</strong> cosmetics, antioxidant in manu-
O
O
O
Ac
N
N
NH 2
3-ABA
O-acetylation Or O-sulfonation
N-nitrinium ion N-acetyl-nitrinium ion
Non-acetylated 3-NBA-DNA adducts Acetylated 3-NBA-DNA adducts
Ac
O
O
R
Ac
N