Aldisine Alkaloids from the Philippine Sponge <i>Stylissa </i><i>m</i><i>assa</i> Are Potent Inhibitors of Mitogen-Activated Protein Kinase Kinase-1 (MEK-1)

Abstract

Raf/MEK-1/MAPK cascade inhibitor activity-directed fractionation of the sponge Stylissa massa afforded eight known alkaloids: aldisine (1), 2-bromoaldisine (2), 10Z-debromohymenialdisine (3), 10E-hymenialdisine (4), 10Z-hymenialdisine (5), hymenin (6), oroidin (7), and 4,5-dibromopyrrole-2-carbonamide (8). Both 4 and 5 showed significant enzyme inhibitory activity (IC(50) 3 and 6 nM, respectively). Secondary assays identified these compounds as potent MEK-1 inhibitors. Compounds 4 and 5 also inhibited the growth of human tumor LoVo cells.