Formazan Derivative Research Articles

In vitro chemosensitivity testing of leukemic cells: development of a semiautomated colorimetric assay.

A rapid chemosensitivity assay was developed, employing the human continuous leukemic cell lines HL 60, K 562, FLG 29.1. This automated colorimetric assay is based on the characteristic of viable, metabolically active cells to cleave p-iodonitrotetrazolium violet (INT) into a red formazan derivative, whose optical density is readable at 492 nm by an automated microtiter-plate reader photometer. A linear relationship was found between the viable cell number and the optical density of INT cleaved by the cellular samples. Dead cells did not reduce INT and did not interfere with the formazan derivative generation and the photometric reading. Leukemic cell lines were also tested for INT formazan derivative generation after exposure to antileukemic drugs at various concentrations, representative of plasma levels obtainable in vivo. A dose-dependent inhibition was detected, with different sensitivity patterns, related both to the drugs and to the different cell lines. A significant correlation between the viable cell number and the amount of tetrazolium salt cleaved was also demonstrated after drug exposure. INT assay allows the processing of a great number of samples and gives the opportunity to screen several drugs, saving time and yielding fully reliable results.

A revised method for the spectrophotometric determination of glyoxylic acid

The spectrophotometric determination of glyoxylic acid at 520 nm based on formation of the 1,5-diphenyl formazan derivative is revised. The colour can be developed at room temperature if the acid or its sodium salt is pure. The molar absorptivity is improved to 32 250 l mol −1 cm −1. The differences from the earlier procedures are discussed.

Diagnostic Accuracy of the Nitroblue Tetrazolium Test

The nitroblue tetrazolium (NBT) test was performed in 22 normal control subjects and in 101 patients with bacterial and nonbacterial illnesses. A maximum of 10% of neutrophils of healthy subjects are capable of reducing NBT dye to a black formazan derivative. Three of eight untreated patients with bacteremia had normal NBT test results. The mean NBT value for untreated bacteremic patients was 21.5%. In patients with acute bacterial infection without bacteremia, 68% had a positive NBT test, the mean NBT value being 20%. Positive NBT tests were noted in three of four patients with viral illnesses, four of five patients with Hodgkin disease, and two of four with lymphomas. The NBT test has some value in diagnosing bacterial infections; however, it may be misleading and should be interpreted in the light of the clinical picture and other laboratory data.

Quantitative reduction of triphenyl tetrazolium chloride as a measure of viability in cereal seeds

The reduction of 2,3,5-triphenyl tetrazolium chloride (TTC) to a coloured formazan derivative by dehydrogenase enzyme systems in viable seeds has been examined. TTC reduction occurs in dry but not wetmilled tissue and the coloured product could be extracted by any of several organic solvents. This formazan product was estimated spectrophotometrically at 480 nm. The influence of fineness of grinding the tissue, TTC concentration, period of treatment, sample size, vacuum infiltration of the milled tissue with TTC and of extracting solvent were examined and a standard procedure is suggested. Using this procedure, a close correlation between seed viability and TTC reduction was demonstrated. The advantages of this method over the widely used topographical method for estimating seed viability with TTC are discussed.

Studies on Dormancy of0Gladiolus Corms. I. Refinement of the Triphenyl Tetrazolium Chloride Method for Estimating the Dormancy of Gladiolus Corms

SummaryThe level of dehydrogenase activity was determined in different parts of gladiolus corms and cormels during various stages of dormancy by a refined triphenyl tetrazolium chloride (TTC) method, in which tissue is considered to be active if the red formazan derivative is produced. A negative correlation between the depth of dormancy and the rate of TTC reduction was found. In corms the terminal bud was found suitable for determining the state of dormancy, but in cormels samples of the whole structure were taken.

A new technique for direct detection of glycoproteins and polysaccharides after electrophoresis or immunoelectrophoresis in agar gel

A technique for the detection of glycoproteins and polysaccharides after electrophoresis or immunoelectrophoresis in agar gels is described. The method is based on the formation of aldehyde-aryl hydrazones from the carbohydrates oxidized by periodic acid. The aldehyde-aryl hydrazones are subsequently converted to a formazan derivative by coupling with a diazonium salt.