Synthetic approaches towards bedaquiline and its derivatives

Synthetic approaches and therapeutic applications of FDA-approved antibacterial agents: A comprehensive review from 2003 to 2023

The increasing threat of antibiotic resistance has necessitated the development of new antibacterial agents. 33 novel antibacterial agents have been approved by the U.S. Food and Drug Administration (FDA) within the two-decade timeframe from 2003 to 2023. These novel antibacterial agents included new chemical classes, such as lipopeptides, 18-membered macrolides, diaromatic quinolones, and nitroimidazoles, as well as modified existing classes, such as quinolones, tetracyclines, β-lactams, macrolides, oxazolidinones, and aminoglycosides. Nonetheless, during these twenty years, approval for new antibiotics was notably absent in 6 different years, and the total number of antibiotics approved was considerably less than that of other drug classes, including anticancer drugs. In this review, we provide an extensive analysis of the synthetic approaches and therapeutic applications of these approved antibacterial agents. We believe that this review will help further research on potential antibacterial agents for clinical use and development of next generation of antibacterial agents.

Synthesis of arylated tetrahydrobenzo[H]quinoline-3-carbonitrile derivatives as potential hits for treatment of diabetes

Aim: Quinoline scaffolds are serving as the core structure for numerous antifungal, analgesic, antipyretic, anti-inflammatory drugs as well as have also been investigated for their potential antidiabetic properties. Though further exploration is required in this area as the current antidiabetic agents, such as acarbose, miglitol and voglibose, are associated with several adverse side effects. In this context, arylated tetrahydrobenzo[H]quinoline-3-carbonitrile derivatives were designed and evaluated as potential antidiabetic agents.Materials & methods: A one-pot multicomponent reaction of 6-methoxy-1-tetralone with ethyl cyanoacetate, ammonium acetate and varying aldehydes yielded a range of new arylated tetrahydrobenzo[h]quinoline-3-carbonitrile molecules 1-36.Results: Compounds 2-5, 12, 13, 19 and 32-34 showed excellent inhibition against α-amylase (IC50 = 3.42-15.14 μM) and α-glucosidase (IC50 = 0.65-9.23 μM) enzymes in comparison to the standard acarbose (IC50 = 14.35 μM). In addition, all compounds revealed significant to moderate DPPH radical scavenging activity (SC50 = 21.30-138.30 μM) compared with BHT (SC50 = 64.40 μM). Kinetic studies confirmed competitive inhibition mode, while molecular docking studies comprehend ligands' interaction with enzyme's active sites and absorption, distribution, metabolism, and excretion analysis confirms that all synthetic derivatives are nontoxic.Conclusion: This research offers a range of lead candidates to become antidiabetic agents after further advanced study.

Application of Chiral Transfer Reagents to Improve Stereoselectivity and Yields in the Synthesis of the Antituberculosis Drug Bedaquiline

Bedaquiline (BDQ) is an important drug for treating multidrug-resistant tuberculosis (MDR-TB), a worldwide disease that causes more than 1.6 million deaths yearly. The current synthetic strategy adopted by the manufacturers to assemble this molecule relies on a nucleophilic addition reaction of a quinoline fragment to a ketone, but it suffers from low conversion and no stereoselectivity, which subsequently increases the cost of manufacturing BDQ. The Medicines for All Institute (M4ALL) has developed a new reaction methodology to this process that not only allows high conversion of starting materials but also results in good diastereo- and enantioselectivity toward the desired BDQ stereoisomer. A variety of chiral lithium amides derived from amino acids were studied, and it was found that lithium (R)-2-(methoxymethyl)pyrrolidide, obtained from d-proline, results in high assay yield of the desired syn-diastereomer pair (82%) and with considerable stereocontrol (d.r. = 13.6:1, e.r. = 3.6:1, 56% ee), providing BDQ in up to a 64% assay yield before purification steps toward the final API. This represents a considerable improvement in the BDQ yield compared to previously reported conditions and could be critical to further lowering the cost of this life-saving drug.

Characterization of stress degradation products of bedaquiline fumarate and bedaquiline by LC-PDA and LC-MS

Bedaquiline fumarate was a first-in-class diarylquinoline drug used for the treatment of M. tuberculosis and its main biologically active form was bedaquiline. This paper studied and compared the degradation products of bedaquiline fumarate and bedaquiline using LC-PDA, LC-MS, and NMR techniques under thermal, alkaline, acidic, oxidative, and photolytic conditions respectively. A LC method was established and optimized to separate all analytes of bedaquiline fumarate and bedaquiline. All degradation products were identified by LC-HRMS/MS and LC-MSn. Bedaquiline fumarate formed three degradation products (DP1, DP2, and DP3) related to fumarate under photolytic condition and formed demethylation product DP4 under acid condition. Bedaquiline formed four degradation products (IM1, IM2, IM3, and IM4) related to the side chains of tertiary alcohol and tertiary amine groups under photolytic condition and formed DP4 under acid condition. The two compounds were stable under thermal, alkaline, and oxidative conditions. DP1 and DP2 indicate that the fumarate could take cis-trans isomerization under light condition. DP3, IM3 and IM4 were first reported degradation products of bedaquiline fumarate and bedaquiline. Compared the degradation behavior of bedaquiline fumarate with bedaquiline, the fumarate form can make the side chain of bedaquiline more stable. It is better to avoid acid and light contact during their storage and manufacturing process.

Synergistic Li/Li Bimetallic System for the Asymmetric Synthesis of Antituberculosis Drug TBAJ-587

TBAJ-587, an analogue of the antituberculosis drug bedaquiline (BDQ), bearing a diarylquinoline skeleton retains the high bacterial potency, is less toxic, and has a better pharmacokinetic profile than the parent molecule, which has entered phase I clinical trials. In contrast to its fascinating bioactivity, however, the highly efficient synthesis of this molecule is still an unsolved challenge. Herein, the first asymmetric synthesis of TBAJ-587 based on a synergistic Li/Li bimetallic system is reported. The product could be obtained in an excellent yield of 90% and an enantiomeric ratio (er) of 80:20. Furthermore, the reaction could be conducted on a 5 g scale, and the product was obtained with 99.9:0.1 er after a simple recrystallization. The realization of this protocol will greatly aid the demand for clinical drug production.

Quinoline Hydrazide/Hydrazone Derivatives: Recent Insights on Antibacterial Activity and Mechanism of Action

Antibiotics are becoming gradually ineffective due to drug resistance, leading to greater difficulty in the treatment of infectious diseases. Therefore, the development of new chemical entities with different mechanisms of action is essential in the fight against resistant microorganisms. Various studies have shown that quinoline hydrazide/hydrazone derivatives possess several biological activities, such as antimalarial, antitubercular, anticancer, anti-inflammatory, and antimicrobial. Among these activities, the antibacterial activity of quinoline hydrazide/hydrazone derivatives is noteworthy. The synthetic flexibility of the quinoline ring has led to the development of a wide range of structurally diverse quinoline hydrazide/hydrazone derivatives, which can act at various bacterial targets such as DNA gyrase, glucosamine-6-phosphate synthase, enoyl ACP reductase, and 3-ketoacyl ACP reductase. This review emphasizes the antibacterial potential of various reported quinoline hydrazide/hydrazone derivatives based on substitution in the quinoline ring. The antibacterial activity of various metal-quinoline hydrazide/hydrazone complexes is also discussed. The aim of this review is to assemble and scrutinize the latest reports in this promising area of drug development.

Diastereoselectivity is in the Details: Minor Changes Yield Major Improvements to the Synthesis of Bedaquiline**

Bedaquiline is a crucial medicine in the global fight against tuberculosis, yet its high price places it out of reach for many patients. Herein, we describe improvements to the key industrial lithiation‐addition sequence that enable a higher yielding and therefore more economical synthesis of bedaquiline. Prioritization of mechanistic understanding and multi‐lab reproducibility led to optimized reaction conditions that feature an unusual base‐salt pairing and afford a doubling of the yield of racemic bedaquiline. We anticipate that implementation of these improvements on manufacturing scale will be facile, thereby substantially increasing the accessibility of this essential medication.

The Medicinal Chemistry of Chalcones as Anti-Mycobacterium tuberculosis Agents

Abstract:

Tuberculosis (TB), a highly fatal infectious disease, is caused by Mycobacterium tuberculosis (Mtb) that has inflicted mankind for several centuries. In 2019, the staggering number of new cases reached 10 million resulting in 1.2 million deaths. The emergence of multidrug-resistance-Mycobacterium tuberculosis (MDR-TB) and extensively drug-resistant-Mycobacterium tuberculosis (XDR-TB) is a global concern that requires the search for novel, effective, and safer short-term therapies. Nowadays, among the few alternatives available to treat resistant-Mtb strains, the majority have limitations, which include drug-drug interactions, long-term treatment, and chronic induced toxicities. Therefore, it is mandatory to develop new anti-Mtb agents to achieve health policy goals to mitigate the disease by 2035. Among the several bioactive anti-Mtb compounds, chalcones have been described as the privileged scaffold useful for drug design. Overall, this review explores and analyzes 37 chalcones that exhibited anti-Mtb activity described in the literature up to April 2021 with minimum inhibitory concentration (MIC90) values inferior to 20 µM and selective index superior to 10. In addition, the correlation of some properties for most active compounds was evaluated, and the main targets for these compounds were discussed.

Defueling the cancer: ATP synthase as an emerging target in cancer therapy

Reprogramming of cellular metabolism is a hallmark of cancer. Mitochondrial ATP synthase (MAS) produces most of the ATP that drives the cell. High expression of the MAS-composing proteins is found during cancer and is linked to a poor prognosis in glioblastoma, ovarian cancer, prostate cancer, breast cancer, and clear cell renal cell carcinoma. Cell surface-expressed ATP synthase, translocated from mitochondrion to cell membrane, involves the angiogenesis, tumorigenesis, and metastasis of cancer. ATP synthase has therefore been considered a therapeutic target. We review recent various ATP synthase inhibitors that suppress tumor growth and are being tested for the clinic.

Synthesis and evaluation of pyridine-derived bedaquiline analogues containing modifications at the A-ring subunit

Despite promising efficacy, the clinical use of the anti-tubercular therapeutic bedaquiline has been restricted due to safety concerns. To date, limited SAR studies have focused on the quinoline ring (A-ring), and as such, we set out to explore modifications within this region in an attempt to discover new bedaquiline variants with an improved safety profile. We herein report the development of unique synthetic strategies that facilitated access to novel bedaquiline analogues leading to the discovery that anti-tubercular activity could be retained following replacement of the quinoline motif with pyridine heterocycles. This discovery is anticipated to open up multiple new avenues for exploration in the design of improved anti-tubercular therapeutics.

Inhibitors of F1F0-ATP synthase enzymes for the treatment of tuberculosis and cancer

The spectacular success of the mycobacterial F₁F₀-ATP synthase inhibitor bedaquiline for the treatment of drug-resistant tuberculosis has generated wide interest in the development of other inhibitors of this enzyme. Work in this realm has included close analogues of bedaquiline with better safety profiles and 'bedaquiline-like' compounds, some of which show potent antibacterial activity in vitro although none have yet progressed to clinical trials. The search has lately extended to a range of new scaffolds as potential inhibitors, including squaramides, diaminoquinazolines, chloroquinolines, dihydropyrazolo[1,5-a]pyrazin-4-ones, thiazolidinediones, diaminopyrimidines and tetrahydroquinolines. Because of the ubiquitous expression of ATP synthase enzymes, there has also been interest in inhibitors of other bacterial ATP synthases, as well as inhibitors of human mitochondrial ATP synthase for cancer therapy. The latter encompass both complex natural products and simpler small molecules. The review seeks to demonstrate the breadth of the structural types of molecules able to effectively inhibit the function of variants of this intriguing enzyme.