Effects of Malachite Green and Its Major Metabolite, Leucomalachite Green, in Micromass Cultures of Rat Embryonic Cells

Embryonic mesenchyme limb (LB) and midbrain (CNS) cells cultured at high density were exposed to different concentrations of the fungicide malachite green (MG) and its major metabolite leucomalachite green (LMG). The concentration response curves were analysed, and two endpoints were calculated: the concentrations (μg/mL) that produced 50% inhibition of viability/proliferation (IC50-P) and differentiation (IC50-D). In LB as well as in CNS cultures, dose-dependent inhibition of both processes was observed. MG was approximately 200 to 300 times more toxic than LMG. The reduction of cell survival and differentiation took place at similar concentrations (P/D~1). IC5-P values ranged from 0.02-0.08 and 5-17μg/mL for MG and LMG, respectively. Malachite green was strongly teratogenic in both, LB and CNS cultures (IC50-D<10 μg/mL). The mean IC50-D (μg/mL) for LMG was 15.6±0.41 (LB) and 3.7±0.15 (CNS).