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

AD 0261 exhibits potent inhibitory activity on lipid peroxide generation (IC50: 0.022 μM) and superoxide anion production (IC50: 0.9-4.0 μM). It dose-dependently inhibits cytokine release/production from PHA-P-stimulated lymphocytes and all lymphocyte activation parameters, achieving 50% inhibition within 1-10 μM. AD 0261 also 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.