Effect of Food Additive E171 and Titanium Dioxide Nanoparticles (TiO2-NPs) on Caco-2 Colon Cancer Cells

The food coloring agent E171 raises many questions concerning its negative impact on human health because of the fact that it contains nanoparticle fractions (NPs, diameter < 100 nm). Numerous studies showed its influence on organisms, including the ability to disrupt the intestinal barrier. In the present study, we verified the potential toxicity and pro-inflammatory activity of three different E171 samples (containing NPs fractions) and one TiO2 NPs sample (60-600 <mu>g mL(-1)) towards Caco-2 colon cancer cells. The experiments revealed no significant changes in terms of the vitality of Caco-2 cells after 24 h of exposure (XTT test). However, after 72 h, a decrease in the proliferation of Caco-2 cells caused by three TiO(2 )substances was observed. Moreover, deterioration of the metabolic activity of Caco-2 cells (ATP test) by all analyzed substances at 300 and 600 mu g mL(-1) was seen. While a 24-h exposure to each tested substance resulted in a negligible release of LDH, a prolonged exposure (72 h) indicated an elevated release of LDH, suggesting potential toxicity. All TiO2 samples induced the elevated release of two primary proinflammatory cytokines, i.e., IL-1 beta and TNF-alpha, in a dose-independent manner. The discrepancies in the results come from the differences in the share of individual sizes in four TiO2 products.