Three Parameter Cytotoxicity Test Kits

IN CYTOTOX products are available worldwide

XTT test principle

Viable cells depend on an intact mitochondrial respiratory chain and an intact mitochondrial membrane. Toxic agents can be identified using mitochondrial dehydrogenases from viable cells.

XTT (2,3-bis[2-methoxy-4-nitro-5-sulfopheny]-2H-tetrazolium-5-carboxyanilide inner salt) is a tetrazolium salt that is cleaved to formazan by the succinate dehydrogenase system which belongs to the mitochondrial respiratory chain, and is only active in viable cells. The mitochondrial succinate dehydrogenase reduces the yellow tetrazolium salt into soluble orange formazan in the presence of an electron coupling reagent.

In contrast to the insoluble formazan salt crystals of MTT, XTT is converted to a water-soluble formazan product without the need for a solubilization step prior spectrophotometric quantification. The enzyme activity is measured at 480 nm (optimum) or at 450 nm.

SRB test principle

Cell proliferation, measured as total protein synthesis, is a very sensitive toxicology marker. Sulforhodamine B (SRB, Acid Red 52) is an anionic dye that binds electrostatically to cellular proteins. The fixed dye is solubilized and is measured photometrically at OD 540 nm with a reference filter of 690 nm. The OD values correlate up to 1.8 OD units with total protein synthesis rate and therefore with cell proliferation.

CVDE test principle

This is a simple assay useful for obtaining quantitative information about the relative density of adherent cells in 96-well plates. After incubation with the test compound, the culture medium is discarded and the cells are washed to remove residual proteins of the culture medium which would interfere with the dye CVDE. CVDE is a dye that binds electrostatically to nuclear proteins and stains DNA.

After elimination of excess dye and solubilization of the fixed dye CVDE, the amount taken up by the cells can be measured spectrophotometrically at 540 nm and can be correlated to cell number.

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