title: Esters of Pyrazinoic Acid Are Active against Pyrazinamide-Resistant Strains of Mycobacterium tuberculosis and Other Naturally Resistant Mycobacteria In Vitro and Ex Vivo within Macrophages.
abstract: Pyrazinamide (PZA) is active against major Mycobacterium tuberculosis species (M. tuberculosis, M. africanum, and M. microti) but not against M. bovis and M. avium. The latter two are mycobacterial species involved in human and cattle tuberculosis and in HIV coinfections, respectively. PZA is a first-line agent for the treatment of human tuberculosis and requires activation by a mycobacterial pyrazinamidase to form the active metabolite pyrazinoic acid (POA). As a result of this mechanism, resistance to PZA, as is often found in tuberculosis patients, is caused by point mutations in pyrazinamidase. In previous work, we have shown that POA esters and amides synthesized in our laboratory were stable in plasma (M. F. Simões, E. Valente, M. J. Gómez, E. Anes, and L. Constantino, Eur J Pharm Sci 37:257-263, 2009, http://dx.doi.org/10.1016/j.ejps.2009.02.012). Although the amides did not present significant activity, the esters were active against sensitive mycobacteria at concentrations 5- to 10-fold lower than those of PZA. Here, we report that these POA derivatives possess antibacterial efficacy in vitro and ex vivo against several species and strains of Mycobacterium with natural or acquired resistance to PZA, including M. bovis and M. avium. Our results indicate that the resistance probably was overcome by cleavage of the prodrugs into POA and a long-chain alcohol. Although it is not possible to rule out that the esters have intrinsic activity per se, we bring evidence here that long-chain fatty alcohols possess a significant antimycobacterial effect against PZA-resistant species and strains and are not mere inactive promoieties. These findings may lead to candidate dual drugs having enhanced activity against both PZA-susceptible and PZA-resistant isolates and being suitable for clinical development.
authors.affiliation: Research Institute for Medicines, iMed-ULisboa, Faculdade de Farmácia da Universidade de Lisboa, Lisbon, Portugal Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal.
authors.forename: David
authors.identifier: http://orcid.org/0000-0001-9602-1516
authors.initials: D
authors.lastname: Pires
authors.affiliation: Research Institute for Medicines, iMed-ULisboa, Faculdade de Farmácia da Universidade de Lisboa, Lisbon, Portugal.
authors.forename: Emília
authors.initials: E
authors.lastname: Valente
authors.affiliation: Research Institute for Medicines, iMed-ULisboa, Faculdade de Farmácia da Universidade de Lisboa, Lisbon, Portugal Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal.
authors.forename: Marta Filipa
authors.initials: MF
authors.lastname: Simões
authors.affiliation: Research Institute for Medicines, iMed-ULisboa, Faculdade de Farmácia da Universidade de Lisboa, Lisbon, Portugal Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal.
authors.forename: Nuno
authors.initials: N
authors.lastname: Carmo
authors.affiliation: Department of Pharmacy, Lausanne University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: Bernard
authors.initials: B
authors.lastname: Testa
authors.affiliation: Research Institute for Medicines, iMed-ULisboa, Faculdade de Farmácia da Universidade de Lisboa, Lisbon, Portugal constant@ff.ul.pt eanes@ff.ul.pt.
authors.forename: Luís
authors.initials: L
authors.lastname: Constantino
authors.affiliation: Research Institute for Medicines, iMed-ULisboa, Faculdade de Farmácia da Universidade de Lisboa, Lisbon, Portugal Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal constant@ff.ul.pt eanes@ff.ul.pt.
authors.forename: Elsa
authors.identifier: http://orcid.org/0000-0001-5934-0198
authors.initials: E
authors.lastname: Anes
mesh_terms: D000438:Alcohols / Q000494:pharmacology; D000995:Antitubercular Agents / Q000494:pharmacology*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D024881:Drug Resistance, Bacterial; D004952:Esters; D006801:Humans; D008264:Macrophages / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D016955:Moraxella bovis / Q000187:drug effects; D009161:Mycobacterium / Q000187:drug effects*; D015269:Mycobacterium avium Complex / Q000187:drug effects; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D011355:Prodrugs; D011718:Pyrazinamide / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology*
chemical_list: D000438:Alcohols; D000995:Antitubercular Agents; D004952:Esters; D011355:Prodrugs; D011718:Pyrazinamide; C005296:pyrazinoic acid