Effects of some cosmetic dyes and pigments on the proliferation of human foreskin fibroblasts and cellular oxidative stress; potential cytotoxicity of chlorophyllin and indigo carmine on fibroblasts.

Introduction: Fibroblasts and fibroblast-like cells (FLCs) are highly distributed in the dermis layer of the skin and gastrointestinal tract. A few studies have investigated the effects of color additives of cosmetic products on human fibroblasts. Therefore, this in vitro study was conducted to investigate the effects of 9 synthetic and natural dyes (indigo carmine, carmine, sunset yellow, tropaeolin, acid green 25, chlorophyllin, tartrazine, lissamine, and amaranth) on human foreskin fibroblast cells.

Methods: MTT assay was applied to investigate the effects of dyes on human normal fibroblast cells. For investigating the possible mechanism of cytotoxicity, the effect of dyes was evaluated on parameters of cellular oxidative stress including lipid peroxidation and reactive oxygen species (ROS) as well as lactate dehydrogenase.

Results: In the MTT assay, a significant reduction (p ≤ 0.05) was observed in the viability of fibroblast cells by chlorophyllin and indigo carmine at concentrations higher than 10 and 100 (μg/ml), respectively. Acid green 25 caused a significant reduction at very high concentrations (1000 and 2000 μg/ml), which was not toxic. The effect of other investigated dyes was not significant on the fibroblasts. A trend in increased cell proliferation by amaranth and carmine was observed, but this enhancement was not statistically significant. No significant changes were observed in lipid peroxidation or lactate dehydrogenase. Chlorophyllin caused a significant increase in the production of cellular ROS.

Conclusions: Indigo carmine and chlorophyllin had cytotoxicity on human fibroblasts, and thus, further studies are required on their safety of use in cosmetics and pharmaceuticals.