In vitro correlation between two colorimetric assays and the pyruvic acid consumption by fibroblasts cultured to determine the sodium laurylsulfate cytotoxicity.

The target of this research was to determine the cytotoxicity of sodium laurylsulfate on single-layer cultures of human fibroblasts, using two colorimetric methods (neutral red and MTT tests) and the evaluation of the pyruvic acid consumption by the cells. For the determination of the cytotoxicity by colorimetric tests, we have determined the absorbance at 540 nm using a spectrophotometer. Pyruvic acid, present in the culture medium, is the mitochondria's C3 energetic metabolite. So, a measure of the cell's consumption of pyruvic acid was developed. The reaction is as follows: Pyruvic acid + NADH --> Lactic acid + NAD+ and the enzyme employed is the LDH (lactate dehydrogenase). This method can be used to measure cytotoxicity, proliferation, and the cell's activation. The method is rapid, precise, and lacks any toxic byproduct. The absorbance was measured using a spectrophotometer at 340 nm. The consumption of pyruvic acid follows upon the fibroblast's growth. Sodium laurylsulfate cytotoxicity test after 24 h shows that the NR colorimetric test and the pyruvic acid consumption are correctly correlated (r = 0.91, alpha = 0.05). This dosage can be used to study the barrier properties of the corneocyte layer without destroying the artificial skin.