Chemical constituents of Gentianaceae XXIV: Anti-Mycobacterium tuberculosis activity of naturally occurring xanthones and synthetic analogs.

Anti-Mycobacterium tuberculosis H37 RV data are presented for the individual xanthones of Canscora decussata Schult and Swertia purpurascens Wall (Gentianaceae); a few, from the former species, showed significant activity. Additionally, sturcture--activity relationships of these compounds are evaluated on the basis of the minimum inhibitory concentration data of 18 naturally occurring xanthones bearing 1,3,5- 1,3,5,6-, 1,3,6,7-, 1,3,5,8-, 1,3,5,6,7-, and 1,3.6,7,8-oxygenated patterns and six synthetic analogs.