Vidofludimus (SC12267) (4SC-101, SC12267) is a novel small molecule inhibitor of dihydroorotate dehydrogenase (DHODH).

DHODH (human):134 nM

DHODH inhibition assay: In vitro DHODH inhibition assay mixture contains 50 μM decycloubiquinone, 100 μM dihydroorotate, and 60 μM 2,6-dichloroindophenol. The amount of enzyme is adjusted such that an average slope of approximately 0.2 AU/min will be achieved in the assay for the positive control (eg, without inhibitor). Measurements are conducted in 50 mM TrisHCl, 150 mM KCl, 0.1% Triton X-100, and pH 8.0 at 30°C in a final volume of 1 ml. The components are mixed, and the reaction is started by adding dihydroorotate. The reaction is followed spectrophotometrically by measuring the decrease in absorption at 600 nm for 2 minutes. The assay is linear in time and enzyme concentration. Inhibitory studies are conducted in a standard assay with additional variable amounts of inhibitor. For the determination of the IC50 values (concentration of inhibitor required for 50% inhibition), eight different inhibitor concentrations are applied. Each data point is recorded in triplicates on a single measurement day.