Elevated expression of fucosylated glycoconjugates and fucosyltransferases (Fuc-Ts) is found in various tumor cells and has been correlated with aspects of tumor progression such as cell adhesion and metastasis. Thus, fucosyltransferase inhibitors are potentially useful as anti-tumor agents. In the present study, three known spirocyclic drimanes (1, 2, and 3) were isolated from the culture broth of the fungus Stachybotrys cylindrospora. Compound 1 (stachybotrydial) exhibits potent inhibitory activity against alpha 1,3-fucosyltransferase (Fuc-TV) during screening, while compounds 2 and 3 show no such inhibitory activity. Kinetic analysis indicates that compound I is an uncompetitive inhibitor with respect to GDP-fucose and a noncompetitive inhibitor with respect to N-acetyllactosamine with hi values of 10.7 and 9.7 mu M, respectively. In addition, all three compounds also possess inhibitory activity against sialyltransferase (ST) but not against beta 1,4-galactosyltransferase. These observations provide novel chemical structure information that will help in the design of novel Fuc-T and ST inhibitors. (c) 2005 Elsevier Inc. All rights reserved.