The Control of Hydrophobic Compound Exposure in In Vitro Tests for Genotoxicity

Abstract

Several of the OECD recommended tests for genotoxicity are in vitro tests, involving the use of open plastic vessels and culture plates, rich culture media, or metabolic activation. These result in volatile, sorptive, and biotransformation losses of the test compound, and thus to poorly defi ned exposure. This has implications for the apparent sensitivity of the assay as well as for establishing a reliable relationship between concentration and response. These issues are particularly relevant for hydrophobic organic compounds (HOCs) which are diffi cult to initially dissolve in aqueous media and particularly susceptible to sorptive losses. Therefore, the in vitro genotoxicity testing of HOCs requires techniques that compensate for losses and lead to defi ned and constant dissolved exposure concentrations. Here, passive dosing can play a useful role. Passive dosing involves a dominating reservoir of polymer-sorbed HOC acting as a partitioning source to the test medium, maintaining defi ned and constant dissolved concentrations. This chapter introduces passive dosing for the control of HOC dissolved concentrations during in vitro genotoxicity tests, covering considerations for selecting a suitable passive dosing polymer and its dimensioning, as well as procedures for cleaning and loading the dosing polymer with the test HOC(s).

Natural Ingredients Common in the Trás-os-Montes Region (Portugal) for Use in the Cosmetic Industry: A Review about Chemical Composition and Antigenotoxic Properties

“…D. melanogaster as a model raises few ethical concerns [188]. The short life cycle, the distinct developmental stages, the availability of various tools and reagents, known genome sequence, and the physiological similarity of D. melanogaster with humans (namely on dietary input, xenobiotic metabolizing system, antioxidant enzymes, and DNA repair systems) make them an excellent in vivo model organism to rapidly test toxicity in the whole organism and elucidate the molecular mechanisms underlying the toxicity [160]. In biomedical sciences, experimental evidence has implicated oxidative stress in the pathophysiology of several disease conditions [189].…”

The Beauty and the Toxic Beast: Use of Comet Assay to Study Antigenotoxicity of Natural Ingredients

“…The alkaline (pH > 13) Comet assay is a sensitive and rapid method for detecting DNA strand breaks in single cells. It is used in genotoxicological studies to determine oxidative DNA damage occurring in various health conditions (in combination with certain bacterial enzymes), to show the protective effects of various nutritional factors in chemopreventive studies, to determine sequence-or gene-specific damage and repair (in combination with fluorescence in situ hybridisation) as well as for possible diagnoses [38,39]. It has the advantages of identifying DNA damage at the single-cell level, sensitivity for detecting low levels of DNA damage using a small number of cells per sample (<10.000), it has a low cost and ease of application, and a short time needed to perform this assay and eukaryote single cell population can be both in vivo and in vitro [39,40].…”