Yeast Assays

Dioxin-like activity was assessed by the AhR recombinant yeast assay (AhR-RYA) performed as described in Noguerol et al. [79]. BP1, with an EC50 value of 0.61 mg/L showed tenfold more dioxin-like activity than BP3, with an EC50 value of 6.8 mg/L. However, two of their metabolites, 4HB and DHMB, presented 4 and 11 times higher activities, with EC50 values of 0.16 and 0.59 mg/L, respectively. No dioxin-like activity was observed for either 4DHB or THB. 

De Serres FJ, Hoffmann GR, von Borstel J, et al. 1981. Summary report on the performance of yeast assays. In Progress in mutation researeh, vol. 1. Elsevier/North Holland, 67-76. 

Chlorobenzene was not mutagenic in a variety of bacterial and yeast assays. Existing data suggest that genotoxicity may not be an area of concern for chlorobenzene exposure in humans."... 

Figure 19.4 Experimental procedure for the assessment of phototoxicity of formulations using the yeast assay. Formulations are spread on agar previously seeded by yeast cells. Photocytotoxicity is assessed by colonies counting after growth on complete medium, whereas genetically altered colonies (here gene conversion involving the t ptophan locus) are detected using selective growth medium (here tryptophan-free), [39].

I. 8-Methoxypsoralen, chlorpromazine and sunscreen compounds in bacterial and yeast assays. Mutation Research,... 

Routledge, E.J. and Sumpter, J.P. (1996). Estrogenic activity of surfactants and some of their degradation products assessed using a recombinant yeast assay. Environmental Toxicology and Chemistry, 15 241-248. 

Miller, D, Wheals, B. B., and Beresford, N., 2001, Estrogenic activity of phenolic additives determined by an in vitro yeast assay, Env. Health Persp. 109 133-138. 

DIPE has been tested for genotoxic activity in bacterial mutation assays, a yeast assay for mitotic gene conversion, and in tests using rat liver and Chinese hamster ovary cells with structural chromosome damaging the end point. Negative responses were observed in the bacterial and yeast assays. 

Estrogenic activity assayed by the yeast assay (Section 7.3.5) has been used to fractionate samples of domestic sewage treatment effluent (Desbrow et al. 1998). It was shown that the major estrogenic activity could be accounted for by the presence of 17p estra-diol (2.7 to 48 + 16 ng/1) and estrone (1.4 to 76 + 10 ng/1), whereas concentrations of 17a-ethynylestrone were much lower (0.2 to 7.0 + 3.7 ng/1). Assays for the adverse effect of these compounds on fish is discussed in Section 7.3.5. 

Not all chemicals exposed to the yeast assay are amenable to this screen. However, a widely held assumption, that yeast cell walls present a major preclusive physi-... 

All of the synthetic sterols were assayed in rad52 DNA-damaging and RAD bioassays and some selected analogs have also been tested for cytotoxicity to Vero cells the results are presented in Table 7. All synthetic 7a-hydroxy analogs showed activity in our DNA-damaging bioassay with 37 and 38 having activity comparable to natural sterols isolated from Pseudobersama mossambicensis. 7a-Hydroxy sterols were also active in Vero cell cytotoxicity assay. However, an inverse correlation between activity in the yeast assay and the cytotoxicity assay was noted. Thus, the 7a-hydroxy sterol which was the most active in the DNA-damaging assay was the epoxide 38, with... 

In contrast to 7a-hydroxy sterols the 7p-hydroxy analogs 45 and 46 were completely inactive in the yeast assay, but showed moderate cytotoxicity in the Vero cell assay. These results suggested that the bioactivity of 7p-hydroxy sterols may involve a different mechanism of action than their a-counterparts. The sp-hydroxy sterols 47, 48 and 49 were found to be inactive in the yeast assay regardless of their side-chain functionalities and were not tested in the Vero cell assay. The results also indicated the requirement of a hydroxy function at C-7 of the sterol nucleus for biological activity in this class of compounds. 

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