2,4-Dialkyl-8,9,10,11-tetrahydrobenzo[g]pyrimido[4,5-c]isoquinoline-1,3,7,12(2H,4H)-tetraones as new leads against Mycobacterium tuberculosis.

Given the re-emergence of tuberculosis in Europe and beyond, the search for novel bio-active compound classes against this disease is of utmost importance. As a result of a high intrinsic tolerance of the etiological agent, Mycobacterium tuberculosis, towards most antibiotics and xenobiotics, the search for such new compounds is far from trivial. Further exacerbated by the rapid generation and spread of drug resistant M. tuberculosis and fuelled by the HIV/AIDS pandemic, halting the tuberculosis epidemic is of paramount importance. As part of our program to design new 2-aza-anthraquinones with anti-mycobacterial activity, various dialkyltetrahydrobenzo[g]pyrimido[4,5-c]isoquinolinetetraones were designed and synthesised. The compounds were submitted to a biological evaluation in which the activity against M.tb H37Rv(lux) was observed, as well as the acute toxicity towards J774 A.1 macrophages. From these results, the selectivity index was calculated. Furthermore, the activity of the most promising compounds was further studied against a multi-drug resistant LAM-1 strain and against intracellular replicating M.tb. The study was further extended with a comet assay and a VITOTOX™ assay to investigate the possibility of observable genotoxic effects caused by these compounds.

Anti-mycobacterial activity of 1,3-diaryltriazenes.

The rapid generation and spread of the drug resistant tuberculosis has led to an ongoing demand for novel compounds for therapeutic use. Identification and study of compounds with the ability to inhibit Mycobacterium tuberculosis is of paramount importance. For this reason, a library of substituted 1,3-diaryltriazenes based on the acting component of the anti-trypanosomal drug, diminazene aceturate was created and evaluated for its potential as anti-tubercular agent. Several compounds were identified with sub-micro molar inhibitory concentrations against M. tuberculosis and other clinically relevant mycobacterial species such as Mycobacterium bovis, Mycobacterium avium and Mycobacterium ulcerans. Although the library of the compounds showed a considerable acute cytotoxicity, a genotoxicity could not be observed. Finally, the triazene 14 was selected with the best biological properties (IC50 = 3.26 µM, NI50 = 24.22 µM, SI = 7.44). The compound 14 showed the ability to inhibit the growth of intracellular replicating and multi-drug resistant M. tuberculosis. The results suggest the molecule to be an interesting scaffold for further study and optimization.

Biological evaluation of diazene derivatives as anti-tubercular compounds.

Despite efforts made in chemotherapeutic research in the past and present, Mycobacterium tuberculosis (M.tb), the etiological agent of tuberculosis, still causes more than a million deadly casualties each year, second only to HIV. The rapid generation and spread of drug resistant strains, a problem exacerbated by co-infection with HIV demands further efforts in the investigation of novel classes of anti-tubercular compounds. A library of eight substituted diazenecarboxamides, three carbamoyldiazenecarboxylates and four diazene-1,2-dicarboxamides was synthesized in a straightforward manner followed by a biological evaluation of the compounds. We observed minimal inhibitory concentrations below 10 µg/mL against the H37Rv lab strain of M.tb. Three compounds that showed a potency of 90% growth inhibition of M.tb at a concentration lower than 10 µg/mL were further evaluated and showed potency against other clinically relevant mycobacterial species such as Mycobacterium bovis, Mycobacterium avium and Mycobacterium ulcerans. The selected compounds were examined for acute cell toxicity on a murine macrophage like monocyte cell line J774 A.1 in which the cell viability was reduced by 50% at concentrations ranging from 7.4 µg/mL to 20.7 µg/mL. Neither of the three compounds showed signs of genotoxicity by VITOTOX or by Comet assay. The study was complemented by demonstration of the inhibition of intracellular replication of M.tb H37Rv inside J774 A.1 cells at 2 µg/mL concentration and the susceptibility of a MDR LAM-1 strain at concentrations between 5 and 1 µg/mL of the most active compound.