A diverse 5,000-compound library was synthesized from commercially available diamines and screened for activity against Mycobacterium tuberculosis in vitro, revealing 143 hits with MIC equal to or less than 12.5 µM. New prospective scaffolds with antitubercular activity derived from homopiperazine, phenyl-and benzyl substituted piperazines, 4-aminomethylpiperidine, 4-aminophenylethylamine, 4,4'-methylenebiscyclohexylamine were identified. Compound SQ775 derived from homopiperazine, and compound SQ786 derived from benzylpiperazine had potent antimicrobial activity against M. tuberculosis in experimental animals in vivo.Among infectious diseases, tuberculosis (TB) remains the leading single-agent killer in the world: 2 billion people are infected with latent TB and at risk for development of active disease and, annually, more than 8 million people advance to active and contagious TB. More than 2 million people die of pulmonary TB every year. [1][2][3] Decades of misuse of existing antibiotics and poor compliance with a prolonged TB drug regimen that involves four different drugs for two months, and two drugs for an additional four months, have created an epidemic of drug-resistant TB. In countries where adequate supplies of the drugs are not readily available, the prevalence of multi-drug resistant TB (MDR-TB) is reported to be as high as 50%. 4,5 In the early 1990s, New York City had one of the worst outbreaks of MDR-TB the country has ever experienced, and the city spent nearly $1 billion over two years on containment. 6 Over the last few years our research efforts have been focused on the discovery of novel scaffolds with antimycobacterial activity and the development of new anti-tubercular agents that can improve the current therapeutic regimen and be effective in treatment of MDR-TB. We synthesized several combinatorial libraries, totaling over 100K compounds, and screened them against Mycobacterum tuberculosis (M. tuberculosis). The first library of 63,238 compounds with the 1,2-ethylenediamine pharmacophore of ethambutol (EMB) 7 lead to the identification of a drug candidate, SQ109 (N-Geranyl-N'-(2-adamantyl)ethane-1,2-diamine). [7][8][9] To further enhance structural diversity, we designed, synthesized, and evaluated * Author to whom correspondence should be addressed. Elena Bogatcheva, Sequella, Inc., 9610 Medical Center Drive, Suite 200, Rockville, MD 20850, (301) for antitubercular activity other diamine libraries, with an emphasis on modification of the linker between two nitrogen atoms, Figure 1. Here we present the synthesis and in vitro screening of a diverse library derived from commercially available "ready-to-use" diamine templates that led to identification of new scaffolds with activity against M. tuberculosis. Preliminary in vivo efficacy data of selected hits are also reported. HHS Public AccessA targeted diamine library of approximately 5,000 compounds was synthesized in one step on 96-well plates from commercially available diamines via solution phase reductive alkylation in ...

New delivery vehicles and routes of delivery were developed for the capuramycin analogue SQ641. While this compound has remarkable in vitro potency against Mycobacterium tuberculosis, it has low solubility in water and poor intracellular activity. We demonstrate here that SQ641 dissolved in the water-soluble vitamin E analogue ␣-tocopheryl polyethylene glycol 1000 succinate (TPGS) or incorporated into TPGS-micelles has significant activity in a mouse model of tuberculosis.SQ641 is an analogue of capuramycin (CM), a naturally occurring nucleoside-based compound produced by Streptomyces griseus. It was derived from a library of over 7,000 CM analogues created by Daiichi-Sankyo (Japan) and was identified as the most potent of the translocase I (TL1) inhibitors, with good activity against mycobacteria (2-4, 8, 9). The target of CM and its analogues is TL1, an essential enzyme for biosynthesis of bacterial cell walls. It is an ideal drug target because inhibition of TL1 leads to cell death and the enzyme is unique to bacteria, reducing the likelihood of toxicity.Sequella licensed the rights to develop the CM analogue library and extended the studies of SQ641. Following on the work performed by Daiichi-Sankyo, we demonstrated (7, 8) that SQ641 shows good activity against both Mycobacterium tuberculosis (MIC ϭ 1.0 g/ml) and Mycobacterium avium complex (MIC ϭ 0.016 to 16 g/ml) bacteria and kills M. tuberculosis faster than many other antituberculosis (anti-TB) drugs, including isoniazid (INH) and rifampin (rifampicin). The SQ641 compound has an extraordinary postantibiotic effect of 55 h against M. tuberculosis and is active against multidrug-resistant M. tuberculosis. SQ641 is strongly synergistic with ethambutol, streptomycin, and SQ109, Sequella's lead antitubercular drug in clinical trials, and is effective in preventing the development of drug-resistant mutants of M. tuberculosis.Unfortunately, SQ641 has limited water solubility and is rapidly expelled from infected cells via P glycoprotein-mediated rapid efflux (4). These limitations result in only modest intracellular activity against M. tuberculosis and poor in vivo activity. In the rapid mouse TB model (6), SQ641 in aqueous solution did not completely prevent body weight loss, and in the chronic model of TB, SQ641 was only able to reduce CFU in the lungs by 0.7 log, compared to the levels for the infected and untreated control groups (data not shown).We were able to overcome these shortcomings by the addition of ␣-tocopheryl polyethylene glycol 1,000 succinate (TPGS), a water-soluble vitamin E analogue (Eastman, Kingsport, TN). We previously published data demonstrating that formulations of TPGS-solubilized SQ641 and TPGS-based SQ641 micelles improved SQ641 solubility and demonstrated higher intracellular activity than SQ641 in aqueous solution (7). In this study, we investigated the activity of these TPGSbased formulations of SQ641 in the chronic mouse model of TB.

In vitro, SQ641 was the most potent of the capuramycin analogues against all NTM tested, both laboratory and clinical strains.

The last 10 years have seen resurgent industry activity in discovery and development of new drugs for the treatment of tuberculosis (TB), a growing widespread and devastating (more than 2 million deaths annually) bacterial infection that is of increasing concern in developing and developed nations alike. This review describes drugs currently being evaluated in the clinic for treatment of uncomplicated and drug resistant pulmonary TB, and updates the literature on 5 new drugs that entered clinical trials in the last 4 years.

We recently reported that compounds created around a dipiperidine scaffold demonstrated activity against Mycobacterium tuberculosis (Mtb) (Bogatcheva, E.; Hanrahan, C.; Chen, P.; Gearhart, J.; Sacksteder, K.; Einck, L.; Nacy, C.; Protopopova, M. Bioorg. Med. Chem. Lett.2010, 20, 201). To optimize the dipiperidine compound series and to select a lead compound to advance into preclinical studies, we evaluated the structure-activity relationship (SAR) of our proprietary libraries. The (piperidin-4-ylmethyl)piperidine scaffold was an essential structural element required for antibacterial activity. Based on SAR, we synthesized a focused library of 313 new dipiperidines to delineate additional structural features responsible for antitubercular activity. Thirty new active compounds with MIC 10-20μg/ml on Mtb were identified, but none was better than the original hits of this series, SQ609, SQ614, and SQ615. In Mtb-infected macrophages in vitro, SQ609 and SQ614 inhibited more than 90% of intracellular bacterial growth at 4μg/ml; SQ615 was toxic to these cells. In mice infected with Mtb, weight loss was completely prevented by SQ609, but not SQ614, and SQ609 had a prolonged therapeutic effect, extended by 10-15days, after cessation of therapy. Based on in vitro and in vivo antitubercular activity, SQ609 was identified as the best-in-class dipiperidine compound in the series.