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Four novel compounds consisting of two new pimaranes, lecheronol A (1) and lecheronol B (2), an acylated cycloartane, 3-O-beta-lauroyl-cycloart-(23E)-en-25-ol (10), and a highly oxygenated novel chalconoid, alpha,beta,3,4,5,2',4',6'-octahydroxydihydrochalcone (12), were isolated along with seven known triterpene derivatives and three flavonol glucosides from Mycobacterium tuberculosis growth-inhibiting fractions of the CH(2)Cl(2)/MeOH (1:1) extract of the aerial parts of Sapium haematospermum. Compounds 1, 3 (3 alpha-hydroxyolean-12-ene), 8 [3 alpha-hydroxylup-20(29)-en], and 9 (cycloartanol) were found most active, with MIC values of 4, 12.2, 13.4, and 8 microg/mL, respectively. Cytotoxicity tests in Vero cells for compounds 1, 3, 8, and 9 gave IC(50) values of 104.8, 127.2, 127.2, and 102.4 microg/mL, respectively.

Bioassay-guided fractionation of the antibacterial CH(2)Cl(2)-MeOH extract obtained from the aerial parts of the Argentinean plant Caiophora coronata led to the isolation of a new triterpene, 1beta,3beta-dihydroxyurs-12-en-27-oic acid, 1, and a new iridoid, 1alpha-methoxy-6alpha,10-dihydroxyisoepiiridomyrmecin (caiophoraenin), 2, along with the known iridoid isoboonein 3. Their structures were established by spectroscopic techniques (1D and 2D NMR, HRFABMS, FTIR). The MIC values of isolated compounds were determined against methicillin-sensitive (MSSA) and -resistant (MRSA) strains of Staphylococcus aureus, Bacillus subtilis (BS), vancomycin-resistant Enterococcus faecium (VREF), Escherichia coli (EC), E. coli imp (ECimp), and Candida albicans (CA). Compound 1 was found active against BS, MSSA, MRSA, VREF, and ECimp with MIC values of 2, 4, 4, 4, and 16 microg/mL, respectively.

Screening of plants from South America for antitubercular activity and subsequent assay-guided fractionation resulted in the isolation and characterization of several pentacyclic triterpenoids. The MIC values of 22 triterpenoids were determined using the radiorespiratory BACTEC assay and range from 8 microM to above 128 microM. The structure-activity relationships are discussed.