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Bioassay-guided chromatographic separation of the antimycobacterial extract of the leaves of Piper sanctum afforded 14 new compounds, identified as 2-oxo-12-(3‘,4‘-methylenedioxyphenyl)dodecane (1), 2-oxo-14-(3‘,4‘-methylenedioxyphenyl)tetradecane (2), 2-oxo-16-(3‘,4‘-methylenedioxyphenyl)hexadecane (3), 2-oxo-18-(3‘,4‘-methylenedioxyphenyl)octadecane (4), 2-oxo-14-(3‘,4‘-methylenedioxyphenyl)-trans-13-tetradecene (5), 2-oxo-16-(3‘,4‘-methylenedioxyphenyl)-trans-15-hexadecene (6), 2-oxo-18-(3‘,4‘-methylenedioxyphenyl)-trans-17-octadecene (7), 2-oxo-16-phenyl-trans-3-hexadecene (8), methyl [6-(10-phenyldecanyl)tetrahydropyran-2-yl]acetate (9), methyl 2-(6-tridecyltetrahydro-2H-pyran-2-yl)acetate (10), methyl 2-(5-tetradecyltetrahydro-2-furanyl)acetate (11), 2-oxo-14-(3‘,4‘-methylenedioxyphenyl)-trans-3-tetradecene (12), 2-oxo-16-(3‘,4‘-methylenedioxyphenyl)-trans-3-hexadecene (13), and 2-oxo-16-phenyl-3-hexadecane (14). In addition, p-eugenol (15), methyleugenol (16), Z-piperolide (17), demethoxyyangonin (18), 5,6-dehydro-7,8-dihydromethysticin (19), cepharanone B (20), piperolactam A (21), cepharadione B (22), N-trans-feruloyltyramine (23), and N-trans-(p-coumaroyl)tyramine (24) were obtained from the anti-TBC stem extract of the plant. GC-MS and HPLC analyses of the essential oils of the leaves and stem revealed that safrol (25) was the major component of the oils. Compounds 2, 3, 6, 18−21, and 24 inhibited the growth of Mycobacterium tuberculosis when tested by the MABA assay, with MIC values ranging from 4 to 64 μg/mL.

In an effort to develop new and more potent therapies to treat tuberculosis, a library of compounds was screened for M. tuberculosis UDP-Gal mutase inhibition. Nitrofuranylamide 1 was identified as a hit in this screen, possessing good antituberculosis activity. This paper describes the synthesis and evaluation of an expanded set of nitrofuranylamides. We have discovered a number of nitrofuranylamides with submicromolar M. tuberculosis MIC values and acceptable therapeutic indexes. The MIC activity did not correlate with UDP-Gal mutase inhibition, suggesting an alternative primary cellular target was responsible for the antituberculosis activity. The compounds were only active against mycobacteria of the tuberculosis complex. On the basis of these results, four compounds were selected for in vivo testing in a mouse model of tuberculosis infection, and of these compounds one showed significant antituberculosis activity.

Four novel compounds consisting of two new pimaranes, lecheronol A (1) and lecheronol B (2), an acylated cycloartane, 3-O-β-lauroyl-cycloart-(23E)-en-25-ol (10), and a highly oxygenated novel chalconoid, α,β,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 CH2Cl2/MeOH (1:1) extract of the aerial parts of Sapium haematospermum. Compounds 1, 3 (3α-hydroxyolean-12-ene), 8 [3α-hydroxylup-20(29)-en], and 9 (cycloartanol) were found most active, with MIC values of 4, 12.2, 13.4, and 8 μg/mL, respectively. Cytotoxicity tests in Vero cells for compounds 1, 3, 8, and 9 gave IC50 values of 104.8, 127.2, 127.2, and 102.4 μg/mL, respectively.

The emergence of resistant strains of Plasmodium falciparumand Mycobacterium tuberculosisunderscores the need for novel drugs that are effective against these microorganisms.

Pyridines and pyrazines substituted with 1,2,4-oxadiazole-5-ones, 1,2,4-oxadiazole-5-thiones, and 1,3,4-oxathiazoline-2-ones were synthesized and tested against Mycobacterium tuberculosis. The two former ring systems were documented in the literature to act as carboxylic acid isosteres. The latter series was synthesized as possible synthetic intermediates to 1,2,4-thiadiazole-3-ones and was included in this study due to their interesting activity. Pivaloyloxymethyl derivatives of the isosteres were also prepared in order to increase their lipophilicity and therefore improve their cellular permeability. The derivatized isosteres were expected to be biotransformed by esterases to the active species after penetration of the mycobacterial cell wall. Biological properties of the compounds were compared with the unmodified polar isosteres of pyrazinoic and nicotinic acids. The majority of the compounds exhibited activities ranging from 0.5 to 16 times the potency of pyrazinamide.

Dicationic 2,5-bis(4-guanidinophenyl)furans 5a−5f, 2,5-bis[4-(arylimino)aminophenyl]furans 6a−6b and 6e−6k, and 2,5-bis[4-(alkylimino)aminophenyl]furans 6c−6d have been synthesized starting from 2,5-bis[tri-n-butylstannyl]furan. Thermal melting studies with poly dA•dT and the duplex oligomer d(CGCGAATTCGCG)2 demonstrated high DNA binding affinities for a number of the compounds. The binding affinities are highly dependent on structure and are significantly affected by substituents both on the phenyl rings of the 2,5-diphenylfuran nucleus and on the cationic centers. Of the 17 novel dicationic compounds synthesized, six (6a, 6b, 5b, 6f, 6h, 6i) exhibited MICs of 2 μg/mL or less versus Mycobacterium tuberculosis. Of the compounds screened against Candida albicans, three gave MICs of 2 μg/mL or less (5b, 6h, 6i), and two (5b, 6i) were fungicidal, unlike a standard antifungal drug fluconazole, which was fungistatic. In addition, one of the tested compounds (6i) exhibited a MIC of <1 μg/mL against Aspergillus fumigatus, while also being a fungicidal against this organism. Finally, when evaluated against an expanded fungal panel, compound 6h showed good activity against Cryptococcus neoformans and Rhizopus arrhizus.

Assay-guided fractionation of the antitubercular MeOH−CH2Cl2 extract obtained from Lippia turbinata led to the isolation of four novel triterpenoids&sbd;3β,25-epoxy-3α,21α-dihydroxy-22β-(3-methylbut-2-en-1-oyloxy)olean-12-ene-28-oic acid (1); 3β,25-epoxy-3α,21α-dihydroxy-22β-angeloyloxyolean-12-ene-28-oic acid (2); 3β,25-epoxy-3α,21α-dihydroxy-22β-tigloyloxyolean-12-ene-28-oic acid (3); and 3β,25-epoxy-3α-hydroxy-22β-(2-methylbutan-1-oyloxy)olean-12-ene-28-oic acid (4)&sbd;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.

Three novel triterpenes, 3,4-seco-olean-12-ene-3,28-dioic acid (4), 3α-hydroxyolean-11-en-28,13β-olide (5), and 3α-hydroxyoleane-11:13(18)-dien-28-oic acid (6), were isolated from the aerial parts of the Argentinean shrub, Junellia tridens. Another five compounds&sbd;oleanolic (1), oleanonic (2), and epioleanolic acids (3), all biosynthetically related to the three new oleananes, and epibetulinic acid (7) and sitosterol (8)&sbd;were also isolated. Structures were elucidated primarily by 1D and 2D NMR and mass spectrometry, and all protons and carbons of the three novel compounds were fully assigned by NMR. We report the minimum inhibitory concentrations of these compounds against Mycobacterium tuberculosis and conclude that they are responsible for antitubercular activity originally observed in the crude plant extract. LC-MS data is provided on the occurrence of triterpenes 1−6 in six other species of Junellia.

The metabolic response of freshly harvested, nude-mouse-derived Mycobacterium leprae to biophysical parameters was studied to facilitate an understanding of axenic culture requirements. Quantitation of intracellular ATP and the rate of [U-14C]palmitic acid incorporation into phenolic glycolipid I (PGL-I) were used as metabolic indicators after axenic incubation in modified Dubos medium under various biophysical conditions. PGL-I synthesis was optimal at 33 degrees C, whereas ATP was optimally maintained at less than or equal to 33 degrees C. Both metabolic indices showed sharp reductions at 37 degrees C. After 5 days of incubation, PGL-I synthesis and ATP maintenance showed pH optima of 5.1 to 5.6, with the higher value appearing optimal for ATP maintenance after extended incubation. Metabolic activity was negatively affected by strong reducing agents, and ATP maintenance was optimal when the gaseous environment was maintained at 2.5 to 10% oxygen. The results may partially explain the failure to cultivate the leprosy bacillus in vitro.

Measurement of intracellular ATP of Mycobacterium leprae after direct in vitro exposure to antimicrobial agents was evaluated as a rapid means of identifying potentially useful therapeutic agents. Nude mouse-derived M. leprae was incubated in an axenic modified Dubos medium in the presence or absence of antimicrobial agents for up to 3 weeks. ATP was then assayed by using the firefly bioluminescence technique. Rifampin, clofazimine, and ethionamide each effected a significantly accelerated rate of ATP decay compared with controls. Dapsone appeared inactive, possibly reflecting a general insensitivity of this system to compounds acting at certain loci. The system appeared suitable for assessing comparative activity of new structural analogs of clofazimine. Other active compounds included erythromycin, minocycline, chloramphenicol, gramicidin, and, to a lesser extent, cycloserine, cephalothin, ciprofloxacin, tetracycline, and gramicidin S. The penicillins, bacitracin, isoniazid, nalidixic acid, trimethoprim, polymyxin B, and griseofulvin were all inactive. The system appears sensitive to agents with various modes of action and may prove useful as a primary screen for antileprosy drugs.

In an attempt to study the structural dependence of antimycobacterial activity of the guaianolide dehydrocostus lactone and its derivatives, m-chloroperoxybenzoic acid oxidations of dehydrocostus lactone (1a) were performed. Three new monoepoxides, one previously synthesized diepoxide, and two new diepoxides were obtained. Two of the monoepoxides are C-10 epimers (3a, 3b), while the 4(15)-monoepoxide (2) has the 4α-O-configuration. The known diepoxide (4a) contains a C-10 α-epoxide and a β-epoxide at C-4. The diepoxides 4b and 4c, each with a C-4 α-epoxy group, differ in the configuration of the epoxide ring at C-10. Allylic oxidation of dehydrocostus lactone (1a) with selenium dioxide/tert-butyl hydroperoxide afforded the known 3-epizaluzanin C (1b). The relative configurations of compounds 1b−4c were established by 1D and 2D NMR techniques (¹H, ¹³C, COSY, NOESY, HMQC, and HMBC) as well as comparison with literature data. The molecular structures of lactones 1b, 4a, and 4c were determined by single-crystal X-ray diffraction. In radiorespirometric bioassays against Mycobacterium tuberculosis and Mycobacterium avium, dehydrocostus lactone (1a) exhibited minimum inhibitory concentrations of 2 and 16 μg/mL, respectively. In contrast, its monoepoxides (2, 3a, and 3b) and diepoxides (4a−c), as well as its hydrogenated derivatives and other analogues (1b, 1c, 5, and 6), showed significantly lower activities against M. tuberculosis.

Bioactivity-guided fractionation of the petroleum ether extract of Azorella madreporica Clos has led to the isolation of the novel, antitubercular mulinane diterpenoid 1. The structure has been elucidated on the basis of its 1D and 2D NMR spectra and by comparison with mulinolic acid 2 and a dehydration product 3 obtained from 1. The MIC of 1 for growth inhibition of the H37Rv strain of Mycobacterium tuberculosis was determined as 20 μg/mL. LC-MS and NMR have suggested the presence of this new compound in four other species of Azorella.

Leprosy affects over 10 million people in the world. The disease is a model of graded cell-mediated immunity, in this case to the causative organism, Mycobacterium leprae. The clinical manifestations are due to (i) bacterial progression, (ii) immunologic responses of the host, (iii) peripheral nerve damage due to either or both bacterial progression and immunologic responses of the host, and (iv) preventable secondary deformities following nerve damage, which account for most of the stigma of the disease. Treatment modalities are now available to control or minimize the effects of bacterial progression, harmful immunologic responses of the host, peripheral nerve damage, and secondary deformities. Unique biochemical characteristics of M. leprae reside in the cell wall and associated macromolecules. Some of these molecules are potent immunogens in humans, while others constitute the structural integrity of the bacillus. Proteins of M. leprae are currently under intensive investigation as a result of deoxyribonucleic acid cloning of M. leprae genes. Structure-function and antigenic relationships of M. leprae proteins should become available by using recombinant deoxyribonucleic acid procedures coupled with T- and B-cell cloning to advance our understanding of the immunologic reactions encountered in Hansen's disease. Until recently, the study of the immunology of leprosy has been stymied by the lack of immunologically specific M. leprae antigens. The definition of specific antigens and production of recombinant and synthetic immunologic reagents have fostered state-of-the-art research efforts into new immunodiagnostic procedures and development of a leprosy vaccine. Also discussed is progress in understanding of the mechanism(s) underlying the M. leprae-specific immunodeficiency associated with lepromatous leprosy, including the role of suppressor T cells and defective macrophage function. Metabolic studies of M. leprae suggest intact catabolic pathways and energy generation with purine bases and catalase as possible growth factors. Special attention may also need to be given to biophysical parameters for eventual in vitro cultivation. Rapid in vitro systems, using quantitation of bacillary metabolic activity, may soon replace the lengthy mouse footpad test for determining the viability and drug susceptibility of the leprosy bacillus.