Antitubercular activity of triterpenoids from Lippia turbinata

Assay-guided fractionation of the antitubercular MeOH-CH2Cl2 extract obtained from Lippia turbinata led to the isolation of four novel triterpenoidls-3 beta ,25-epoxy-3 alpha ,21 alpha -dihydroyloxy)olean-12-ene-28-oic acid (1); 3 beta ,25-epoxy-3 alpha ,21 alpha -dihydroxy-22 beta -angeloyloxylean-12-ene-28-oic acid (2); 3 beta ,25-epoxy-3 alpha ,21 alpha -dihydroxy-22 beta -tigloyloxylean-12-ene-28-oic acid (3); and 3 beta ,25-epoxy-3 alpha -hydroxy-22 beta-(2-methylbutan-1-oyloxy)olean-12-ene-28-oic acid (4)-together with the known triterpenoids lantanilic acid (5), camaric acid (6), lantanolic acid (7), and rehmannic acid (8). The MIC values of 1-8 for growth inhibition of Mycobacterium tuberculosis were determined in the radiorespirometric BACTEC system.