cerevisiae.Table 1.The IC50 values (��mol/L) of the chemicals measured by the bioluminescence assay having the exposure of 2.5 h or 5 h compared to the results (minimum inhibitory concentration, ��mol/L) of the conventional agar diffusion assay.2.1.1. Antimicrobial agentsEvidently, 5,6-benzoflavone (Table 1) is the most potent among the chemicals tested and concidered as toxic for yeast cells. Additionally, a concentration of 750 nM caused total inhibition of bioluminescence throughout an exposure of 4 hours and at 7.5 nM the bioluminescence response, depending on the exposure time, varied between 41% (after 30 min exposure) of the response in blank to 65% of the response in blank (Figure 1a).

The results are not unexpected, since 5,6-benzoflavone is known to be a strong inducer of certain enzymes belonging to the CYP 450 superfamily and has the same induction potency as the carcinogenic benzo(a)pyrene. For this reason 5,6-benzoflavone is widely used for studies in toxic effects in mammals mediated by aryl hydrocarbon receptor [30]. On the other hand as far as we know, no data in the literature on non-specific toxicity measured by a yeast-based bioassay is available for 5,6-benzoflavone.Figure 1.a. Bioluminescence response to 5,6-benzoflavone in real-time monitoring during exposure of 4 h. Squares (0.75 nM), diamonds (7.5 nM), circles (75 nM) and triangles (750 nM) denote for concentration of 5,6-benzoflavone used, respectively. The error bars …

We also obtained interesting results in an exposure of rapamycin (shown in Figure 1b as an example).

It is clearly evident that the toxicity of 5,6-benzoflavone (Figure 1a) and rapamycin (Figure 1b) can be followed in real-time after the administration of the toxicant and the luciferase substrate D-luciferin. The emission is dose-dependent and the toxicity can be followed kinetically inside the thermostated measurement chamber of Cilengitide the multilabel reader.The bioluminescence responses to nystatin (Figure 2) were different from the responses to other tested chemicals. Low concentrations of nystatin had no inhibitory effect on the yeast sensor cells; the light production was similar to that of the blank (100%).

At a concentration of 0.54-1.08 ��M, the bioluminescence response, depending on the exposure time, varied between 290% (an exposure of 5 hours) and 371% (an exposure of 2.5h), while a concentration of 5.40 ��M caused total inhibition of bioluminescence and can be considered as Carfilzomib toxic for the yeast sensor. After an exposure of 10 hours, the peak values at low concentrations of nystatin were not visible any more. This effect was seen repeatedly and was statistically significant in the control experiments.