Studies on the tumor-promoting activities of additives in biomaterials: inhibition of metabolic cooperation by additives such as pigments and phenolic antioxidants

The inhibitory activities on the intercellular gap-junctional communication were investigated using the V79 metabolic cooperation (MC) assay for the detection of tumor-promoting activities of additives such as pigments and phenolic antioxidants. Among six pigments, four chemicals showed inhibitory activities. The inhibitory potencies were ranked in the following order: sudan I > purple 201 > blue 204 > green 202. Sudan I and purple 201 showed stronger inhibitory activities than lithocholic acid, which is known to be a tumor promotor. However, quinizarine and red 225 did not inhibit at any concentration. Relating to eight phenolic antioxidants, four chemicals also showed inhibitory activities. Combining the present findings with previous ones, there are many factors that have tumor-promoting activities via inhibitory action on gap-junctional intercellular communication in biomaterials.