MORPHOLOGICAL TRANSFORMATION OF SYRIAN-HAMSTER EMBRYO CELLS IN PRIMARY CULTURE BY MALACHITE GREEN CORRELATES WELL WITH THE EVIDENCE FOR FORMATION OF REACTIVE FREE-RADICALS

Malachite green (MG) (green crystals with metallic luster and very sol uble in water) is highly cytotoxic to mammalian cells and also acts as a liver tumor promoter. In view of its industrial importance and poss ible exposure to individuals, MG poses a potential environmental healt h hazard. We have studied the effect of MG on the formation of morphol ogically transformed colonies using Syrian hamster embryo (SHE) cell t ransformation assay. MG induced a dose-related increase in the formati on of transformed foci, the optimum concentration being 0.05 mu g/ml. Electron spin resonance (ESR) analysis using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin-trapping agent showed the formation of reacti ve free radicals during the in vitro metabolism of MG. The present stu dy suggests a close relationship between the morphological transformat ion of SHE cells by MG and the possible involvement of reactive free r adical formation.