Mutagenicity of Heterocyclic Amines by Biomimetic Chemical Models for Cytochrome P450 in Ames Assay

Abstract

Heterocyclic amines (HCAs) are a family of mutagenic and carcinogenic compounds produced during cooking or other burning processes, and exist in the environment. HCAs are metabolically activated by cytochrome P450, conjugated by phase II enzymes, to react with guanine bases. The aim of this study is to establish a chemical model for cytochrome P450 as an alternative to S-9 mix for detecting HCA mutagenicity in Salmonella strain. A chemical model was developed by comparing the mutagenicity of 3-amino-1-methyl-5H-pyrido [4,3-b]indole (Trp-P-2) in the presence of an iron porphyrin and an oxidant. The iron porphyrin derivatives, water-soluble 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrinatoiron (III) chloride (4-MPy) or water-insoluble 5,10,15,20-tetrakis (penta‰uorophenyl)porphyrinatoiron (III) chloride (F 5 P), and the oxidant tert-butyl hydroperoxide (t-BuOOH), magnesium monoperoxyphthalate or iodosylbenzene were used. 4-MPy or F 5 P with t-BuOOH activated Trp-P-2, and the activity was similar with either porphyrin. Water-soluble model has a better chance to detect unstable compound, since the tester strain was exposed in the whole incubation period in the mutation procedure with 4-MPy. The eŠectiveness of 4-MPy/t-BuOOH was evaluated with other HCAs; IQ, MeIQ, MeIQx, Glu-P-1, Glu-P-2, PhIP, Trp-P-1, MeAaC and AaC. All HCAs except for MeAaC and AaC were mutagenic in Salmonella typhimurium TA1538. MeAaC and AaC were not mutagenic in TA1538, but they were mutagenic in S. typhimurium TA1538/pYG219, which overexpresses O-acetyltranferase on the TA1538 genetic background. Although the HCAs mutagenicity with the chemical model was weaker than that with S-9 mix, the chemical models activated HCAs without S-9 mix in the Ames assay.

Ruthenium porphyrin and oxidant convert N-nitrosodialkylamines into direct-acting mutagen in the Ames assay

“…We have already reported that a chemical model, consisting of Fe porphyrin plus hydroperoxide or peracid, oxidised aromatic amines, heterocyclic amines and polyaromatic hydrocarbons to mutagenic compounds. [22][23][24]32 RuMe 3 has efficiently oxidised inactive compounds under mild conditions using Cl 2 pyNO as an oxidant. [26][27][28] The Cl 2 pyNO in the Ames assay can be used at higher concentrations due to the low toxicity.…”

“…We have reported the detection of the mutagenicity of aromatic amines, 22 heterocyclic amines 23 and polyaromatic hydrocarbons 24 by a chemical model in the Ames assay. The N-nitrosodialkylamines mutagenicity was also detected in the presence of 5,10,15,20-tetrakis( pentafluorophenyl)porphyrinatoiron(III) chloride (FeF 5 ) and tert-butyl hydroperoxide (t-BuOOH); however, an increased number of bacteria were required in the assay.…”

Oxidation of N-Alkyl-N-(3-carboxypropyl)nitrosamines by Iron Porphyrin and Oxidant Forms Alkylating Mutagens

“…In the present study, we applied a chemical model for cytochrome P450 as an alternative for metabolic activation to the Ames assay (7,8). Previous reports have shown that the chemical models consisting of iron porphyrin or ruthenium porphyrin plus an oxidant have induced mutagenicity in aromatic amines, heterocyclic amines, polyaromatic hydrocarbons, and N-nitrosodialkylamines in Salmonella strains (20)(21)(22)(23). The 4-MPy plus t-BuOOH system activated MCPN, ECPN, PCPN and BCPN into direct-acting mutagens.…”

Modelling the Effects of Roselle Extract, Potato Peel Flour, and Beef Fat on the Sensory Properties and Heterocyclic Amines Formation of Beef Patties Studied by Using Response Surface Methodology

“…These metabolites react with the DNA of various tissues to form adducts that lead to cancer problems. The HCAs have shown mutagenic capacity in the Ames test [ 10 ] and carcinogenic capacity in studies with rodents [ 11 , 12 ]. Besides, it has been demonstrated the formation of HCAs-DNA adducts in colorectal human tissue [ 13 ].…”