Salmonella/human S9 mutagenicity test: a collaborative study with 58 compounds

Abstract

A large and extensive body of data on the use of human liver S9 fractions in the Salmonella mutagenicity test (Ames test) is presented; the data were obtained from a collaborative study by JEMS/BMS (Bacterial Mutagenicity Test Study Group) members and the Human and Animal Bridging Research Organization (HAB). In this study, the mutagenicity of 58 chemicals, many of which were judged to be human carcinogens by the IARC, was determined by the Ames test (the pre-incubation method at 37 degrees C for 20 min) in the presence of a selected human liver S9 fraction with a high drug-metabolic activity or a pooled human liver S9 fraction with a moderate drug-metabolic activity. For reference, mutagenicity was also examined in the presence of a phenobarbital/5,6-benzoflavone-pretreated rat liver S9 fraction, which is normally used in mutagenicity testing systems. The bacterial test strains consisted of Salmonella typhimurium TA100, TA98 or YG7108. The data indicated that the mutagenicity of chemicals in the rat and human liver S9 fractions varied considerably, depending on the chemicals in question. In addition, a large inter-individual diversity in the mutagenic response to mutagens, depending on the chemical structures of the mutagens, was also demonstrated using two selected human S9 fractions. Most of the mutagens tested in this study (75%; 36 out of 48 compounds that were judged to be mutagenic in at least one S9 fraction) were less mutagenic in the presence of the two human S9 fractions than in the presence of the rat S9 fraction. On the other hand, the other compounds (25%), including some aromatic amines and nitrosamines, showed a more potent mutagenicity in the presence of either one of the two human S9 fractions than in the presence of the rat S9 fraction. These data strongly suggest that the use of human liver S9 fraction in mutagenicity testing systems may be useful for a better understanding of the mutagenic effects of chemicals on humans.

Genotoxicity of acrylamide in vitro: Acrylamide is not metabolically activated in standard in vitro systems

“…The human liver S9 (HLS-104) was prepared from a human liver sample, which was legally procured from the NDRI (National Disease Research Interchange) in Philadelphia, USA, with permission to use for research purpose only. HLS-104 showed high activity of CYP2E1 [Hakura et al, 2005]. We prepared microsomal fraction from the S9 according to an established procedure [Suzuki et al, 2000].…”

Toxic potentials of ten herbs commonly used for aphrodisiac effect in Turkey

“…The S9 mix included 30% of S9 microsomal fractions. S9 mix was 0.083 mL 1.00 M KCl, 0.080 mL 0.25 M MgCl 2 .6H 2 O, 0.063 mL 0.20 M glucose-6-phosphate, 0.250 mL 0.04 M NADP, 1.270 mL 0.20 M NaH 2 PO 4 buffer, and 0.750 mL S9 microsomal fraction (39).…”

Urinary Mutagenicity in Chemical Laboratory Workers Exposed to Solvents

“…A sample was considered positive when the MI was equal to or greater than 2 for at least one of the tested doses and if it had a reproducible dose-response 21) . Several authors have used this parameter in their works [22][23][24][25] . According to Mortelmans and Zeiger 26) , in an important review of the Ames test a widely used approach is to analyze the results and to set a minimum fold increase, usually 2-3 folds, in revertants (over the solvent control) as a cut-off between mutagenic and nonmutagenic responses.…”