AD 0261 is a radical scavenger. It has a strong inhibitory action on the generation of lipid peroxides and superoxide anions.

AD 0261 displays strong inhibitory action on the generation of lipid peroxides (IC50: 0.022 μM) and superoxide anions (IC50: 0.9-4.0 μM). It inhibits cytokine release and/or production from PHA-P-stimulated lymphocytes in a dose-dependent manner. AD 0261 inhibits all parameters which are indicative of lymphocyte activation with 50% inhibition being achieved in a range of 1-10 μM. AD 0261 suppresses ornithine decarboxylase activity (IC50: ~1.0 μM).

For measurement of [3H]TdR incorporation, cells are incubated for 16 h, and additional (6 h) incubation is carried out in the presence of [3H]TdR (0.5 μCi/well). [3H]TdR incorporation is evaluated in a liquid scintillation counter. IL-2 release from lymphocytes is estimated after 20 h incubation by enzyme immunoassay using the commercially available kits. IL-2 receptor expression is quantitated by flow cytometry using a FITC-labelled monoclonal antibody which recognizes a chain of the IL-2 receptor complex. Cell viability is determined by either the trypan blue exclusion test or propidium iodide staining.