Evaluation of some plant-derived secondary metabolites against sensitive and multidrug-resistant Mycobacterium tuberculosis

The results on the bioevaluation of thirty five plant-derived secondary metabolites against one sensitive and three multidrugresistant clinical isolates of Mycobacterium tuberculosis are reported. Results toward the sensitive strain showed that five products gave MIC values of 12.5 μg/mL: the alkaloids 6-methoxydihydrochelerytrine (2) and 6-methoxy-dihydrochelirubine (6), the flavanone pinostrobin (17), 1-hydroxy-benzoisochromanquinone (23) and 23-hydroxy-5a-lanosta-7,9(11),24-triene-3-one (33). These were followed by the peracetylstrictosidine lactam (12) and the quinone aloe-emodin (24) which displayed MICs of 6.25 μg/mL. Finally, liriodenine (8) was the most active (MIC: 3.125 μg/mL) of all secondary metabolites. Results with the multidrug-resistant clinical isolates showed that 6-methoxy-dihydrochelirubine (6) was the most active (MIC: 12.5 μg/mL).