Cytotoxic Activity of LCS-1 is not Only due to Inhibition of SOD1
Background The cytotoxic activity of the pyridazin-3-one derivative LCS-1 was previously suggested to be due to the inhibition of superoxide dismutase 1 (SOD1). However, no direct evidence was provided that LCS-1 inhibits SOD1 within cells.
Methods In this study, we investigated the cytotoxic activity of LCS-1 against bloodstream forms of Trypanosoma brucei , a protozoan parasite that does not express copper/zinc-containing SOD1, but an iron-containing superoxide dismutase (FeSOD).
Results At 250 µM, LCS-1 did not inhibit the activity of FeSOD in cell lysates of bloodstream forms of T. brucei , confirming that the compound is a specific inhibitor of SOD1. However, LCS-1 displayed substantial trypanocidal activity with a minimum inhibitory concentration of 10 µM and a half-maximal effective concentration of 1.36 µM, indicating that the cytotoxic action of the compound cannot solely be due to inhibition of SOD1.