The mechanisms of
catechol-induced cytotoxicity were studied in cultures of
neuroblastoma N2a cells. The minimal cytotoxic concentration after 72 h was 20 micromol x l(-1). The EC50 after 72 h was 38 micromol x l(-1). There was not a correlation between the cytotoxicity and the formation of
quinones in the medium.
Catechol-induced cytotoxicity was increased significantly when
superoxide dismutase (SOD) was added. The addition of
catalase did not protect cells, but this
enzyme reverted the deleterious effect of SOD. The experimental studies showed a detrimental effect of
deferoxamine on
catechol-induced cytotoxicity suggesting that cells need
iron to maintain its metabolism.
NF-kappaB inhibitors increased the cytotoxicity, suggesting that this factor is also important for cell viability.
L-cysteine and
N-acetyl-L-cysteine protected cells significantly in a dose-dependent manner. The use of
monochlorobimane showed that
catechol induced
reduced glutathione (GSH) depletion after 24 h, prior to cell death. The mode of cell death was studied by flow cytometry after double staining with
annexin V and
propidium iodide.
Catechol induced apoptosis after 72 h. Furthermore,
catechol also induced nuclear fragmentation. These data showed that
catechol-induced cytotoxicity to N2a cell was not directly a consequence of
reactive oxygen species production. Rather, it was due to GSH depletion followed by the induction of apoptosis.