Some Properties of 2,3,5-Triphenyltetrazolium Chloride and Several Iodo Derivatives

Aromatic−Aromatic Interaction between 2,3,5-Triphenyl-2H-tetrazolium Chloride and Poly(sodium 4-styrenesulfonate)

Aromatic-aromatic interactions are found between the cationic molecule 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) and the molecule poly(sodium 4-styrenesulfonate) (PSS) which makes the overall interaction of TTC with PSS more intense than the interaction with other polyanions containing sulfonate groups and produces a decrease on the redox ability of TTC. Diafiltration was used to compare the binding of TTC to PSS, poly(sodium vinylsulfonate) (PVS), and the more hydrophobic poly(sodium 2-(N-acrylamido)-2-methyl-propanesulfonate) (PAMPS). The UV-vis spectrum of TTC is changed in the presence of the aromatic polyanion. The 1H NMR signals of TTC are broadened and shifted in the presence of PSS, suggesting the occurrence of pi-pi interactions. Moreover, nuclear Overhauser effects (NOE) between the TTC and PSS protons are found. Possible structures for the complex are proposed.

The histochemical localization of triphosphopyridine nucleotide diaphorase

A histochemical method is described for the localization of triphosphopyridine nucleotide diaphorase using a recently synthesized tetrazolium salt (Nitro-BT). By virtue of the favorable histochemical properties of this reagent, it has been possible to demonstrate that whereas DPN diaphorase is usually restricted to the mitochondria, the TPN diaphorase activity of corresponding cells was distributed throughout the cytoplasm in granules too fine to be considered mitochondria. Furthermore, although the diaphorase alone is responsible for the passage of electrons from TPNH to the tetrazole, it has been found that sites of activity of different TPN-linked dehydrogenases can be visualized in tissue sections, and characteristic loci for each enzyme may be observed. For example, whereas TPN diaphorase and isocitric dehydrogenase have an extensive distribution in the kidney cortex, 6-phosphogluconic dehydrogenase is limited to the cells of the macula densa.

In vitro studies of the metabolism of tissue slices. I. Metabolic and physical factors influencing the penetration of tetrazolium salts

The use of tetrazolium salts for metabolic studies has been dismissed on the basis of their poor penetration into fresh tissue slices. In view of the fact that the penetration of these compounds can be visualized, it was felt that knowledge of the factors involved would be important. Factors, known to influence the penetration of oxygen, were examined with respect to the tetrazolium salts. The penetration of tetrazolium salt into tissue slices was a regular and predictable phenomenon. It was found that decreasing the metabolism of the cells in the slice substantially increased the penetration of these compounds, while increases in metabolism, by addition of substrate (such as succinate) to the incubating medium, considerably decreased their penetration. Increasing concentrations of the salt in the medium resulted in greater but limited penetration. It is our belief that the metabolism of tissue slices can be effectively studied with the aid of the tetrazolium salts, the portion of the population of cells participating in any reaction being accurately established by measuring the depth of the zone of reduced dye.

Acceleration of tetrazolium reduction by bacteria

Conditions were assessed which would permit more rapid recognition of bacterial growth than has been previously reported using tetrazolium salts. Microtitration trays were used. 2-(p-Iodophenyl)-3(p-nitrophenyl)-5-phenyltetrazolium chloride is rapidly reduced by respiring cells in tissue homogenates but is more toxic than other tetrazoliums when added to growing bacterial cultures. Phenazine methosulfate (PMS), an intermediate electron carrier, potentiates tetrazolium reduction. Growth was readily detected by the addition of these compounds after 3 to 4 h of incubation in Schaedler broth. The final concentration prior to addition to tray wells was 1.0 mg/ml for 2-(p-iodophenyl)-3(p-nitrophenyl)-5-phenyltetrazolium chloride and 0.06 mg/ml for PMS. Addition of 0.5 to 0.8 g of agar per liter of broth enhanced subsequent tetrazolium reduction.

Succinate dehydrogenase activity in the developing molar of the Mongolian gerbil Meriones unguiculatus

The distribution of succinate dehydrogenase in the odontogenic tissues in the Mongolian gerbil, ranging in age from 18 days prenatal to 8 days postnatal, was studied. Activity levels were designated negative, trace, slight, moderate, strong and very, dependent upon visual observations. The results indicated increased levels of activity as the tissue layers differentiated from the lamina stage through early apposition. The cell layer displaying the most succinate dehydrogenase activity was the ameloblastic layer while the stratum intermedium layer was the next most active cell layer. Succinate dehydrogenase activity appeared to be related to the degree of differentiation and functional competency of the odontogenic tissues in the Mongolian gerbil.

Tetrazolium salts and formazans

The history of the tetrazolium salts and formazans goes back 100 years, to when Friese (1875) reacted benzene diazonium nitrate with nitromethane, to produce a cherry-red "Neue Verbindung". This was the first formazan. 19 years later, Von Pechmann and Runge (1894) oxidised a formazan to produce the first tetrazolium salt. Many hundreds of tetrazolium salts and formazans were prepared in the following years, but only a handful have found applications in biological research. This article has attempted to describe the properties of these compounds, and to illustrate how the tetrazolium salt-formazan reaction has been exploited to serve an extremely wide variety of functions.

Reduction of tetrazolium salts by pleuropneumonialike organisms

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