Inhibitor of dihydroorotate dehydrogenase (Kd = 12 nM; Ki = 179 nM). Inhibits proliferation of mitogen- or cytokine-stimulated lymphoid cells in vitro by inhibiting cell cycle progression from G1 to S. Imunosuppressive agent. Active metabolite of leflunomide (Cat. No. 2228). Purity 99%. MW (observed): 270.21