Potent and selective phosphodiesterase (PDE) 4 inhibitor (IC50 values are 0.28, > 100, 160 and 330 nM at PDE4, PDE1, PDE2 and PDE3 respectively). Inhibits eosinophil chemotaxis and increases progressive motility of spermatozoa in vitro. Purity 98%. MW (observed): 411.8