9-Hydroxybenfluron induced inhibition of proliferation and metabolism in HeLa cells.

The highest concentration of 9-hydroxybenfluron (HBF) tested, namely 4.05 mumol l-1, induced immediate cytotoxic effects which were manifested by total inhibition of cell proliferation after only 24 h of culture. In a certain proportion of the cells cytolytic effects were observed at longer times of culture. Lower concentrations of HBF induced toxicity that was concentration- and time-dependent. The toxic effect appeared to occur in two phases. Cells, which had lost their ability to divide, did not stop their metabolism in which glutamine was the main source of energy. The results suggest that HBF primarily interferes with one of the phases of the cell cycle and only secondarily influences energy processes. Because benfluron (BF) and HBF have similar effects, it is suggested that the cytotoxicity of BF can be ascribed to the influence of its metabolite, HBF.