Inhibitory effect of ascorbate on cell growth: relation to catalase activity

The effect of ascorbate on cell growth was examined using primary cultured hepatocytes and chondrocytes elicited from guinea pigs and six kinds of cell lines derived from the tissue and blood of mammals. Cells were cultured in medium supplemented with or without ascorbate at various concentrations for 24 and 48 h. There were differences among the cells used here in the effect of ascorbate on growth, and also in the concentrations of ascorbate required to lower cell viabilities. This indicates that different cell species have varying sensitivities to ascorbate in medium. On the other hand, cells such as HL-60, which showed growth inhibition at higher concentrations of ascorbate in medium among observed cells, were damaged by the exposure to higher concentrations of hydrogen peroxide (H2O2). Furthermore, there was a positive correlation between the activity of catalase in cells that decomposed H2O2 and the concentration of ascorbate required to lower cell viability (p < 0.01). These results indicate that the concentration of ascorbate in medium required to inhibit cell growth depends on the activity of catalase in the cells.