Triphenyltetrazolium

As will be discussed later (Sections 7.4.2.1 and 7.4.2.2), tetrazolium salts are not stable under basic conditions. Depending on the substituent, however, acidic conditions may allow some transformations. Thus, 2,3,5-triphenyltetrazolium chloride can be converted to the disulfonic acid derivative by the action of concentrated sulfuric acid or oleum.1... 

Tetrazolium salts are unstable in basic solutions yielding intense colors. This reaction is still little understood.233,234 In the reaction of 2,3,5-triphenyltetrazolium with hydroxide, it is postulated that a hydroxide ion is involved first as a counterion later leading to the hypothetical A-hydroxy-formazan (147).229 Weiner studied the kinetics of this reaction and identified 1,3,5-triphenylformazan in 10% yield. In concentrated alkaline solutions, the A-hydroxytetrazole (148) has been isolated from triphenyltetrazolium chloride (Scheme 19).235,236... 

Materials Required Hydrocortisone acetate 0.350 g aldehyde-free absolute ethanol 100 ml triphenyltetrazolium chloride solution [a 0.5% w/v solution of 2,3,5, -triphenyltetrazolium chloride in aldehyde-free ethanol (96%)] 10 ml dilute tetramethylammonium hydroxide solution [Dilute 10 ml of tetramethylammonium hydroxide solution (10%) to 100 ml with aldehyde-free ethanol (96%). It contains about 1% w/v of C4H13NO. To be prepared immediately before use] 10 ml. 

Our final conclusion was therefore that the mechanism of intramolecular oxidative cyclization of 1,3,5-triphenylformazan to 2,3,5-triphenyltetrazolium perchlorate involves cyclization of the initial radical cation and deprotonation as the rate-determining step, following the mechanistic scheme e-c-P-e. 

Growth conditions in deep-well microtiter plates were optimized with respect to optimal expression of active enzymes (Fig. 2.2.1.1). The best results were obtained with an expression time of 20 h at 37 °C (Fig. 2.2.1.1, lanes 7-9). Subsequently, E. coli cells were enzymatically disrupted by lysozyme treatment, and the carboligase activity was monitored by a modified tetrazolium salt color assay [16], This color assay is based on the reduction of the 2,3,5-triphenyltetrazolium chloride (TTC) 13 to the corresponding formazan 15, which has an intense red color (Fig. 2.2.1.2A). Before screening ofa BFD variant library, substrates and products were tested in the color assay. Neither substrate, benzaldehyde 4 nor dimethoxy-acetaldehyde 8, reduced TTC 13 however, the product 2-hydroxy-3,3-dimethoxy-propiophenone 10 already caused color formation at low concentrations of 2.5-10 mM (Fig. 2.2.1.2B). Benzoin 12 as the product also gave a color change at a similar concentration (data not shown). 

Fig. 2.2.1.2 Colorimetric assay for carboligase activity. A) DMA-HPP 10 reduces 2,3,5-triphenyltetrazolium 13 chloride to the respective formazan 15, which has an intense red color. B) Formation of the red formazan 15 dye can be observed only in the presence of DMA-HPP 10 neither substrate dimethoxyacetaldehyde 8 nor benzaldehyde 4 causes any change in color.

The photochemical change of 2,3,5-triphenyltetrazolium chloride (CXXX) to triphenylformazan (CXXXI) and 2,3-(2,2 -biphenylene) 5-phenyltetrazolium chloride (CXXXII) is an example of a photooxidation-photoreduction process.84 106... 

TOF-SIMS Time-of-flight secondary ion mass spectrometry TTC 2,3,5-Triphenyltetrazolium chloride... 

Cerebral infarct volume was evaluated 22 h after reperfusion in rats subjected to 2 h MCAo. Animals were sacrificed by decapitation and the brains were rapidly removed. Eight serial sections from each brain were cut at 2-mm intervals from the frontal pole using a rat brain matrix (Harvard Apparatus, MA, USA). To measure ischemic damage, brain slices were stained in a solution containing 2% 2,3,5-triphenyltetrazolium chloride (TTC) in saline, at 37 °C. After 10 min incubation, the slices were transferred to 10% neutral buffered formaldehyde and... 

Because amounts of vitamin B12 are very low in foods, tissues, and body fluids, bioautography is used before densitometry. A selected strain of Escherichia coli is used as a microorganism for the bioautography. Growth spots are enhanced by the addition of 2,3,5-triphenyltetrazolium chloride, which is converted to the red-colored formazan by E. coli growth. Determination of vitamin B12 in human plasma and erythrocytes was accomplished by one-dimensional bioautography.A... 

Figure 11 Activity staining of a cell-free extract from the Synechococcus transformant. The extracts were separated on a 8% homogeneous nondenaturing polyacrylamide gel. The gel was incubated with menthylviologen (0.125% w/v) and 2,3,5-triphenyltetrazolium chloride (0.125% w/v) in a hydrogen-saturated solution as described in material and methods. Lane 1, soluble protein fraction from Chostridium pasteurianum, 0.357 mg. lane 2, total protein fraction from the transformant harboring pKE4-9SH, 0.383 mg. lane 3, total protein fraction from Synechococcus wildtype cells, 0.429 mg.

When 2,3,5-triphenyltetrazolium chloride (16), formed by oxidation of the formazan 15, is exposed to sunlight or ultraviolet light in dilute solution, it disproportionates to the bridged tetrazolium salt 17 and the formazan (Scheme 3). By carrying out the irradiation in the presence of dilute nitric acid the formazan is reoxidized to the tetrazolium salt (16), so that high yields of the bridged salt result. Reduction of 17 gives first the stable. 

Formazans are accessible by interaction of hydrazones with arenediazonium salts. When R = Ph, the colourless 2,3,5-triphenyltetrazolium chloride is formed. It is reconverted into the red formazan by reducing agents, e.g. by reducing enzymes. By this method, the part of a cell in which biological reductions occur can be stained. 

Dehydrogenase is an enzyme present in all living microbiological material. The presence of this enzyme can be determined using 2,3,5-triphenyltetrazolium chloride. This colourless water-soluble compound is reduced to a red compound called formasan in the presence of dihydrogenase enzyme. This compound can be extracted in ethanol, the content determined photometrically, and a relationship with microbiological activity can then be estabhshed. 

TPTZ 2,3,5-Triphenyltetrazolium chloride 2,3,5-Triphenyl-2H-tetrazolium chloride 2,3,5-Triphenyl-2H-tetrazolium chloride monohydrate TTC... 

Triphenylstannium acetate. See Fentin acetate Triphenylstibine. See Triphenylantimony 2,3,5-Triphenyltetrazolium chloride 2,3,5-Triphenyl-2H-tetrazolium chloride 2,3,5-Triphenyl-2H-tetrazolium chloride monohydrate. See Tetrazolium chloride Triphenyl thiophosphate 0,0,0-Triphenyl thiophosphate. See Triphenyl phosphorothionate... 

Periodate-permanganate aqueous solution of Nal04 (2%, m/v) mixed 2 1 (v/v) with solution of KMn04 (1%, m/v) in aqueous Na2C03 (2%, m/v) Triphenyltetrazolium chloride 2,3,5-triphenyltetrazolium chloride (4%, m/v) in methanol, mixed 1 1 (v/v) with NaOH (1 moll" ) in methanol... 

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