The dichloromethane extract of the stem bark of Warburgia ugandensis afforded three new coloratane sesquiterpenes, namely: 6α,9α- dihydroxy-4(13),7-coloratadien-11,12-dial (1), 4(13),7-coloratadien-12,11-olide (2), and 7β-hydroxy-4(13),8-coloratadien-11,12-olide (3), together with nine known sesquiterpenes, i.e., cinnamolide-3β-acetate (4), muzigadial (5), muzigadiolide (6), 11α-hydroxymuzigadiolide (7), cinnamolide (8), 7α-hydroxy-8-drimen-11,12-olide (9), ugandensolide (10), mukaadial (11), ugandensidial (12), and linoleic acid (13). Their structures were assigned on the basis of 1D and 2D-NMR spectroscopic and GC-MS analysis. The compounds were examined for their antimycobacterial activity against Mycobacterium aurum, M. fortuitum, M. phlei and M. smegmatis; and the active constituents showed MIC values ranged from 4 to128 μg/ml compared to the antibiotic drugs ethambutol (MIC ranged from 0.5 to 8 μg/ml) and isoniazid (MIC ranged from 1 to 4 μg/ml). © 2005 Elsevier Ltd. All rights reserved.
