Resazurin indicator

This indicator possesses the advantage that it may be used under aerobic conditions, in contrast to dyes such as methylene blue (115). Resazurin has also been applied in the study of the dehydrogenation of isopropanol and sorbitol (103), (118). 

The relationship of the dicarboxylic amino acids, aspartic and glutamic acids to this process has also been studied (106). This investigation has been facilitated by a quantitative method for the codetermination (23) of the dehydrogenation indicator, resazurin, and its reduction product, resorufin. The wood destroying molds used were Trameles cinnabarina and Lentinus lepideus. 

The metabolism studies with cyanide present showed no dehydrogenation whatsoever of the substrate. It is thus considered likely that the resazurin and the resorufin interact with some metal bearing system, possibly the cytochromes participating in the hydrogen transfer. Although the resazurin (or resorufin) may interact in a system several steps removed from the dehydrogenation of the particular substrates, the relative rates of reduction of the indicator are still comparable with the relative oxidation rates of the substrates. 

Fermentation of lactose during the growth of micro-organisms in milk has a major effect on its redox potential. The decrease in the h of milk caused by the growth of lactic acid bacteria is shown in Figure 11.3. A rapid decrease in h occurs after the available 02 has been consumed by the bacteria. Therefore, the redox potential of cheese and fermented milk products is negative. Reduction of redox indicators (e.g. resazurin or... 

Resazurin is a chemical redox indicator that functions like the tetrazolium compounds. The resazurin reduction assay approach has successfully replaced tritiated thymidine incorporation for some HTS applications (Ahmed, Gogal, and Walsh 1994 Shum et al. 2008). Resazurin can be dissolved in physiological buffers resulting in an intense blue solution that is added directly to growing... 

One example is the known interference by reducing compounds that affect the chemical conversion of substrate to a colored indicator. This is especially true for the tetrazolium assays (Ulukaya, Colakogullari, and Wood 2004 Chakrabarti et al. 2000 Pagliacci et al. 1993 Collier and Pritsos 2003). The growing list of interfering compounds includes ascorbic acid and sulfhydryl reagents such as glutathione, coenzyme A, dithiothreitol, etc. Similar interferences by compounds that affect the oxidation and reduction chemistry of cells are likely to cause artifacts with the resazurin reduction assay. Assays that measure markers of metabolism also can be influenced by the pH of the culture medium and other factors that may stimulate or stress the metabolic rates of cells. 

FIGURE 6.4 Comparison of effects of Alamar blue (resazurin) and GF-AFC reagents on viability of cells measured using a luminescent ATP assay. Resazurin or GF-AFC was incubated with 10,000 DU145 cells per well for 18 hr prior to measuring ATP as an indicator of cell viability. Alamar blue reagent is more toxic to cells. 

FIGURE 6.5 Comparison of sensitivity of resazurin reduction and GF-AFC cleavage assays for detection of numbers of cells. Values are plotted as signal-to-noise (S N) ratios. Comparison of data at S N = 3 indicates approximately 30-fold better sensitivity of the GF-AFC assay after 30 min of incubation compared to resazurin incubated for 3.5 hr. 

Beilstein Handbook Reference) Azoresorcin BRN 0221382 Diazoresorcinol EINECS 208-987-1 7-Hydroxy-3H-fenoxazin-3-on-10-oxid 7-Hydroxy-3H-phenoxazin-3-one 10-oxide NSC 10438 3H-Phenoxazin-3-one, 7-hydroxy-, 10-oxide Resazoin Resazurin Resazurine. An acid-base indicator pH 3.8 orange, pH... 

A suitable redox indicator is Resazurin. The method is based on visual determination of colour change of the redox indicator with time relative to microbiological activity. 

Methylene blue is the most widely used dye and it undergoes a color change from blue to white when reduced. Resazurin, like methylene blue, is a redox indicator but unlike methylene blue, it undergoes a series of color changes from blue and mauve to pink as it is reduced. The use of these dyes is restricted to products that do not contain inherent reducing components. 

Nutrients (P, N, Fe, Mg, Ca, K) and trace elements required for aerobic degradation (Mn, Cu, Co, Ni, B, Mo, Se) are provided by the mineral nutrient solutions defined by the ASTM and ISO methods. Also added are the reduction agent sodium sulfide and the redox indicator resazurin. The main difference between these two mineral nutrient solutions is the buffer system used (hydrogen carbonate buffer with ASTM and hydrogen phosphate buffer with ISO standard). While the ISO methods quantifies the CO2 dissolved in water and considers it when calculating the degradation rates, the ASTM method does not offer this option [286]. 

ProUferation/Viability Assays Based on Metabolic Activity of Cells Besides the incorporation of nucleosides into DNA, cell-viability dyes and kits have become valid options to monitor cell viability, activation and the increasing number of viable cells during cell proHferation. Table 5 Hsts the assays that are based on the metabolic activity of cells. They are also used as an indirect measure of cytotoxicity. The viability/metabolic reagents based on redox indication dyes like tetrazolium (MTT, XTT, MTS WST-1) and resazurin (Alamar Blue) are popular substitutes for radioactive compovmds. The tetrazolium assays are colorimetric assays based on bioreduction of tetrazolium salt into a either insoluble (MTT) or soluble (XTT, MTS,WST-1) colored substance formazan by mitochondrial succinate dehydrogenase. The reaction occurs only in live cells, and the... 

To evaluate bacterial contamination of wool fibers, it is suggested to use an index suggested by A. 1. Sapozhnikova, which characterizes discoloration rate of resazurin solution, a weak organic dye and currently hydrogen acceptor. It is also indicator of both presence and activity of reductase enzyme [40]. 

Fig.1 Metabolism of resazurin (Alamar Blue ) by Trichomonas vaginalis. Resazurin is rapidly reduced to reso-rufin by the parasites, but is also reduced by the ascorbic acid in the medium, making it an unreliable indicator for the presence of T. vaff/nafe trophozoites. The ascorbate or a similar reducing agent is essential for trophozoite growth and thus cannot be omitted from the medium. Resorufin is stable in the medium but is rapidly further reduced by the trophozoites...

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