Amycolatopsin B is a glycosylated polyketide isolated by Microbial Screening Technologies. The amycolatopsins are closely related to the ammocidins and apoptolidins. Amycolatopsin A and C, bearing a hydroxyl group at the 6-methyl position, selectively inhibit the mycobacteria, M. bovis and M. tuberculosis and exhibit a low level of cytotoxicity toward mammalian cells.