Potent selective inhibition of 7-O-methyl UCN-01 against protein kinase C.
 UCN-01 is a staurosporine-related compound that was isolated from the culture broth of Streptomyces sp.
 and shows potent and selective inhibitory activity against protein kinase C.
 Cellular inhibitory activity of UCN-01 against protein kinase C and cytotoxicity of UCN-01 were compared with those of staurosporine.
 When the mechanism of inhibitory activity was investigated in vitro, UCN-01 as well as staurosporine inhibited the activity of the catalytic domain of protein kinase C.
 In spite of direct inhibition against the catalytic domain of protein kinase C, cytotoxicity of UCN-01 was much lower than that of staurosporine.
 In addition, UCN-01 showed more selective inhibitory activity against protein kinase C than did staurosporine because of the sole structural difference at C-7.
 Therefore, a series of 7-O-alkyl derivatives of UCN-01 was synthesized and investigated.
 Interestingly, one of the compounds, the beta-methoxy derivative, showed 3-fold greater potency and 17-fold more selective inhibitory activity against protein kinase C than did UCN-01.
