In vitro and Intracellular Antibacterial Activity of Sudapyridine (WX-081) Against Tuberculosis

Advancements and challenges in tuberculosis drug discovery: A comprehensive overview

Tuberculosis continues to pose a health challenge causing the loss of millions of lives despite the existence of multiple drugs, for treatment. The emergence of drug-resistant strains has made the situation more complex making it increasingly difficult to fight against this disease. This review outlines the challenges associated with TB drug discovery, the nature of Mycobacterium tuberculosis shedding light on the mechanisms that lead to treatment failure and antibiotic resistance. We explore promising drug targets, encompassing inhibition of mycolyarabinogalactan peptidoglycan (MAGP) assembly, mycolic acid biosynthesis, DNA replication, transcription, translation, protein synthesis, and bioenergetics/metabolism pathways. A comprehensive overview of the global pipeline of anti-tuberculosis drugs at various stages of clinical trials, the diverse strategies being pursued to tackle this complex disease. By gaining an understanding of the mechanisms that contribute to resistance development and identifying suitable targets, we can pave the way for more effective treatments and contribute to global efforts to combat drug-resistant tuberculosis.

Bactericidal and sterilizing activity of sudapyridine-clofazimine-TB47 combined with linezolid or pyrazinamide in a murine model of tuberculosis

As an obligate aerobe, Mycobacterium tuberculosis relies on its branched electron transport chain (ETC) for energy production through oxidative phosphorylation. Regimens targeting ETC exhibit promising potential to enhance bactericidal activity against M. tuberculosis and hold the prospect of shortening treatment duration. Our previous research demonstrated that the bacteriostatic drug candidate TB47 (T) inhibited the growth of M. tuberculosis by targeting the cytochrome bc1 complex and exhibited synergistic activity with clofazimine (C). Here, we found synergistic activities between C and sudapyridine (S), a structural analog of bedaquiline (B). S has shown similar anti-tuberculosis efficacy and may share a mechanism of action with B, which inhibits ATP synthesis and the energy metabolism of bacteria. We evaluated the efficacy of SCT in combination with linezolid (L) or pyrazinamide (Z) using a well-established murine model of tuberculosis. Compared to the BPa(pretomanid)L regimen, SCT and SCTL demonstrated similar bactericidal and sterilizing activities. There was no significant difference in activity between SCT and SCTL. In contrast, SCZ and SCTZ showed much higher activities, with none of the 15 mice experiencing relapse after 2 months of treatment with either SCZ or SCTZ. However, T did not contribute to the activity of the SCZ. Our findings emphasize the efficacy and the potential clinical significance of combination therapy with ETC inhibitors. Additionally, cross-resistance exists not only between S and B but also between S/B and C. This is supported by our findings, as spontaneous S-resistant mutants exhibited mutations in Rv0678, which are associated with cross-resistance to B and C.

Non-tuberculous mycobacterial disease: progress and advances in the development of novel candidate and repurposed drugs

Non-tuberculous mycobacteria (NTM) are opportunistic pathogens that can infect all body tissues and organs. In particular, the lungs are the most commonly involved organ, with NTM pulmonary diseases causing serious health issues in patients with underlying lung disease. Moreover, NTM infections have been steadily increasing worldwide in recent years. NTM are also naturally resistant to many antibiotics, specifically anti-tuberculosis (anti-TB) drugs. The lack of drugs targeting NTM infections and the increasing drug resistance of NTM have further made treating these mycobacterial diseases extremely difficult. The currently recommended NTM treatments rely on the extended indications of existing drugs, which underlines the difficulties of new antibiotic discovery against NTM. Another challenge is determining which drug combinations are most effective against NTM infection. To a certain extent, anti-NTM drug development depends on using already available antibiotics and compounds. Here, we aimed to review new antibiotics or compounds with good antibacterial activity against NTM, focusing on their mechanisms of action, in vitro and in vivo antibacterial activities.

Antibacterial activity of the novel compound Sudapyridine (WX-081) against Mycobacterium abscessus

Objective

This study aimed to investigate sudapyridine (WX-081) antibacterial activity against Mycobacterium abscessus in vitro and its effect on in vivo bacterial growth and host survival using a zebrafish model of M. abscessus infection.

Methods

WX-081 in vitro antibacterial activity was assessed based on growth inhibition of M. abscessus standard strain ATCC19977 and 36 clinical isolates. Maximum tolerated concentrations (MTCs) of WX-081, bedaquiline, and azithromycin and inhibition of M. abscessus growth were assessed in vivo after fluorescently labelled bacilli and drugs were injected into zebrafish. Bacterial counts were analysed using one-way ANOVA and fluorescence intensities of zebrafish tissues were analysed and expressed as the mean ± SE. Moreover, Kaplan-Meier survival analysis was conducted to assess intergroup differences in survival of M. abscessus-infected zebrafish treated with different drug concentrations using a log-rank test, with a p value <0.05 indicating a difference was statistically significant.

Results

Drug sensitivity testing of M. abscessus standard strain ATCC19977 and 36 clinical isolates revealed MICs ranging from 0.12-0.96 µg/mL and MIC50 and MIC90 values of 0.48 µg/mL and 0.96 µg/mL, respectively. Fluorescence intensities of M. abscessus-infected zebrafish tissues was lower after treatment with the WX-081 MTC (62.5 µg/mL) than after treatment with the azithromycin MTC (62.5 µg/mL) and the bedaquiline MTC (15.6 µg/mL). When the concentration of WX-081 increased from 1.95µg/mL to 1/8 MTC(7.81µg/mL), the survival rate of zebrafish at 4-9 dpf decreased from 90.00% to 81.67%.

Conclusion

WX-081 effectively inhibited M. abscessus growth in vitro and in vivo and prolonged survival of M. abscessus-infected zebrafish, thus indicating that WX-081 holds promise as a clinical treatment for M. abscessus infection.

Design, synthesis and anti-Tb evaluation of chalcone derivatives as novel inhibitors of InhA

A series of halogenated chalcone derivatives were designed and developed for anti-tubercular activity. Novel molecules were designed and in-silico screening were performed using admetSAR, SwissADME, and Osiris Property Explorer. From the initial filter the top 10 compounds were docked using the Autodock tool 1.5.6. and the binding energies of the docked compounds were higher than the standard drugs Isoniazid.and Ethionamide. Based on the in-silico and docking results, the top halogenated chalcones were synthesized and characterized using FT-IR, mass spectrometry, 1H, and 13C NMR spectroscopy. The chalcones were further evaluated for anti-tubercular activity using MABA against the H37Rv strain. Among the series of compounds, DK12 and DK14 showed potent in-vitro activity, with MICs of 0.8 µg/ml, in comparison with 1.6 µg/ml of the first-line drug Isoniazid. Further molecular dynamics simulations studies for 100 ns revealed that the key interaction with TYR 158 were observed in both DK12 and DK14 in the InhA active site. The compound DK12 further showed significant interactions with PHE 149 and ARG 153 residues and is a hit molecule among the series. Further DK12 and DK14 does not show any significance toxicity. The compounds DK12 needs to be optimized and further investigation to be carried out against InhA.Communicated by Ramaswamy H. Sarma.