Evaluation of colloidal platinum on cytotoxicity, oxidative stress and barrier permeability across the gut epithelium

Colloidal platinum (Pt) is widely consumed due to its health promoting benefits. However, the exact biological effects of these nanoparticles have not been studied in detail, particularly in the gut. In the present study we observed that colloidal Pt was not cytotoxic towards three different epithelial colon cancer cell lines. Co-treatment of the colon cancer cell line Caco-2 with the oxidative stress inducing agent hydrogen peroxide (H(2)O(2)) and colloidal Pt resulted in a significant decrease in H(2)O(2) induced oxidative stress. Colloidal Pt by itself did not induce any oxidative stress. Additionally, both overnight pretreatment of Caco-2 cells with colloidal Pt followed by 1 h treatment with H(2)O(2), or co-treatment of cells for 1 h with colloidal Pt and H(2)O(2) resulted in a significant recovery of cell death. Of note, the same protective effects of colloidal Pt were not observed when the oxidative stress was induced in the presence of 2, 2-azobis (2-amidinopropane) dihydrochloride, indicating that the source of free radicals may define the outcome of anti-oxidant activity of colloidal Pt. Colloidal Pt was also able to cross a model intestinal barrier formed in vitro with differentiated Caco-2 cells easily. Overall, our data indicate that colloidal Pt was not toxic towards intestinal epithelial cells, reduced H(2)O(2) induced oxidative stress, protected from oxidative stress related death of intestinal epithelial cells and could pass a model gut barrier easily. Colloidal Pt can therefore be consumed orally for its anti-oxidant and other health promoting benefits.