SUBSTITUTED XANTHONES AS ANTIMYCOBACTERIAL AGENTS, PART 2 - ANTIMYCOBACTERIAL ACTIVITY

A series of substituted xanthones was tested for their activity agains t four mycobacterial strains (Mycobacterium tuberculosis, M. avium M. lufu, M. smegmatis) by determination of the minimum;inhibitory concent rations (MIC values). For the most active compounds, supplementary cha racterisation was performed by bacterial growth kinetics, which allows a more precise interpretation of their antimycobacterial effects. Fro m the test set, 1-methyl-2,4,7-trinitroxanthone (8a) showed the highes t antimycobacterial activity with a MIC value of 3 mu g/mL against M, tuberculosis, which is comparable to the effect of well known drugs us ed in the treatment of tuberculosis. For all other compounds, the MIC values could not be determined, due to the comparatively low activity and to the poor solubility of the compounds, respectively. The semiqua ntitative evaluation of activity against the different strains of myco bacteria resulted in a classification into three activity classes, whi ch will be used as dependent parameter in QSAR investigations, to be p ublished in Part 3 of this series.