Phytochemical study of the roots of Euphorbia phosphorea Mart. (Euphorbiaceae) was carried out through chromatographic techniques, resulting in the isolation of a new ent-abietane diterpene named 11β,12β-dihydroxy-ent-abieta-8(14),13(15)-dien-16,12α-olide (1), and of nine known ent-abietane diterpenes jolkinolide A (2), jolkinolide E (3), euphorin H (4), euphopilolide (5) jolkinolide F (6), ent-12-hydroxy-12[R]-abieta-8(14),13(15)-dien-16,12-olide (7), ent-11α-hydroxyabieta-8(14),13(15)-dien-16,12α-olide (8), 17-hydroxyjolkinolide B (9) and caudicifolin (10). The structures of all compounds were established using spectroscopic techniques such as 1D and 2D NMR, and the structure of the compound 1 was established also with MS, IR and ECD. All compounds were submitted to an in silico study through of a predictive model and then submitted to in vitro tests against Mycobacterium tuberculosis and M. smegmatis for evaluation of their antimycobacterial activity. Compounds 5 and 9 showed mycobacterial growth inhibition with MIC values of 62.5 μM against M. tuberculosis and M. smegmatis, respectively.

Cytidine deaminase (MtCDA), encoded by cdd gene (Rv3315c), is the only enzyme identified in nucleotide biosynthesis pathway of Mycobacterium tuberculosis that is able to recycle cytidine and deoxycytidine. An M. tuberculosis knockout strain for cdd gene was obtained by allelic replacement. Evaluation of mRNA expression validated cdd deletion and showed the absence of polar effect. MudPIT LC-MS/MS data indicated thymidine phosphorylase expression was decreased in knockout and complemented strains. The cdd disruption does not affect M. tuberculosis growth both in Mid- dlebrook 7H9 and in RAW 264.7 cells, which indicates that cdd is not important for macrophage invasion and virulence.

Tuberculosis remains among the top causes of death triggered by a single pathogen. Herein, a greener synthetic approach for isonicotinoylhydrazones is described using ultrasound energy. These compounds were used as starting materials for synthesizing pentacyanoferrate(II)-isonicotinoylhydrazones, which inhibited the reaction catalyzed by Mycobacterium tuberculosis 2-trans-enoyl-ACP(CoA) reductase (MtInhA) in a time-dependent manner. The most active coordination complex showed an increase of more than ten-fold in the MtInhA inhibition rate constant compared with lead pentacyano(isoniazid)ferrate(II) (IQG607). Additionally, the new series of metal-based compounds demonstrated antitubercular activity against a drug-susceptible Mycobacterium tuberculosis (Mtb) strain and was devoid of toxicity to mammalian cells (IC50 > 20 µmol L-1, half maximal inhibitory concentration). Finally, one of the synthesized compounds showed intracellular activity similar to isoniazid in a macrophage model of Mtb infection, indicating that this chemical class may furnish novel structures to embark on the preclinical phase of anti-tuberculosis drug development.

BACKGROUND Tuberculosis (TB) is an infectious disease caused mainly by the bacillus Mycobacterium tuberculosis. The better understanding of important metabolic pathways from M. tuberculosis can contribute to the development of novel therapeutic and prophylactic strategies to combat TB. Nucleoside hydrolase (MtIAGU-NH), encoded by iunH gene (Rv3393), is an enzyme from purine salvage pathway in M. tuberculosis. MtIAGU-NH accepts inosine, adenosine, guanosine, and uridine as substrates, which may point to a pivotal metabolic role. OBJECTIVES Our aim was to construct a M. tuberculosis knockout strain for iunH gene, to evaluate in vitro growth and the effect of iunH deletion in M. tuberculosis in non-activated and activated macrophages models of infection. METHODS A M. tuberculosis knockout strain for iunH gene was obtained by allelic replacement, using pPR27xylE plasmid. The complemented strain was constructed by the transformation of the knockout strain with pNIP40::iunH. MtIAGU-NH expression was analysed by Western blot and LC-MS/MS. In vitro growth was evaluated in Sauton’s medium. Bacterial load of non-activated and interferon-γ activated RAW 264.7 cells infected with knockout strain was compared with wild-type and complemented strains. FINDINGS Western blot and LC-MS/MS validated iunH deletion at protein level. The iunH knockout led to a delay in M. tuberculosis growth kinetics in Sauton’s medium during log phase, but did not affect bases and nucleosides pool in vitro. No significant difference in bacterial load of knockout strain was observed when compared with both wild-type and complemented strains after infection of non-activated and interferon-γ activated RAW 264.7 cells. MAIN CONCLUSION The disruption of iunH gene does not influence M. tuberculosis growth in both non-activated and activated RAW 264.7 cells, which show that iunH gene is not important for macrophage invasion and virulence. Our results indicated that MtIAGU-NH is not a target for drug development.