Design and Synthesis of Imidazole and Triazole Pyrazoles as Mycobacterium Tuberculosis CYP121A1 Inhibitors

The emergence of untreatable drug-resistant strains of Mycobacterium tuberculosis is a major public health problem worldwide, and the identification of new efficient treatments is urgently needed. Mycobacterium tuberculosis cytochrome P450 CYP121A1 is a promising drug target for the treatment of tuberculosis owing to its essential role in mycobacterial growth. Using a rational approach, which includes molecular modelling studies, three series of azole pyrazole derivatives were designed through two synthetic pathways. The synthesized compounds were biologically evaluated for their inhibitory activity towards M. tuberculosis and their protein binding affinity (K_D). Series 3 biarylpyrazole imidazole derivatives were the most effective with the isobutyl ( 10 f ) and tert-butyl ( 10 g ) compounds displaying optimal activity (MIC 1.562 μg/mL, K_D 0.22 μM ( 10 f ) and 4.81 μM ( 10 g )). The spectroscopic data showed that all the synthesised compounds produced a type II red shift of the heme Soret band indicating either direct binding to heme iron or (where less extensive Soret shifts are observed) putative indirect binding via an interstitial water molecule. Evaluation of biological and physicochemical properties identified the following as requirements for activity: LogP >4, H-bond acceptors/H-bond donors 4/0, number of rotatable bonds 5–6, molecular volume >340 ų, topological polar surface area <40 Ų.     

β-酮脂酰-ACP合成酶（FabH）抑制剂研究进展

脂肪酸的生物合成对病原细菌的存活至关重要。近年来,在这一生物合成途径中所涉及的关键酶引起了人们的广泛关注。其中β-酮脂酰-ACP合成酶Ⅲ(KAS Ⅲ,FabH)控制着细菌脂肪酸生物合成的起始步骤,普遍存在于病原体中且在人体中无其同源蛋白,成为新型抗菌药物靶标研究的热点。抑制FabH酶活性的小分子抑制剂有望成为对细菌具选择性而对人体无毒的广谱抗菌药。本文对脂肪酸的生物合成,FabH相关结构研究以及目前FabH抑制剂的研究进展进行了综述。     

Cephem-Pyrazinoic Acid Conjugates: Circumventing Resistance in Mycobacterium tuberculosis

Tuberculosis (TB) is a leading source of infectious disease mortality globally. Antibiotic-resistant strains comprise an estimated 10 % of new TB cases and present an urgent need for novel therapeutics. β-lactam antibiotics have traditionally been ineffective against M. tuberculosis (Mtb), the causative agent of TB, due to the organism's inherent expression of β-lactamases that destroy the electrophilic β-lactam warhead. We have developed novel β-lactam conjugates, which exploit this inherent β-lactamase activity to achieve selective release of pyrazinoic acid (POA), the active form of a first-line TB drug. These conjugates are selectively active against M. tuberculosis and related mycobacteria, and activity is retained or even potentiated in multiple resistant strains and models. Preliminary mechanistic investigations suggest that both the POA “warhead” as well as the β-lactam “promoiety” contribute to the observed activity, demonstrating a codrug strategy with important implications for future TB therapy.     

毛细管电泳-激光诱导荧光检测分枝杆菌脱氧核糖核酸限制性内切酶谱

建立了毛细管电泳分离-激光诱导荧光检测（CE-LIFD）分析分枝杆菌脱氧核糖核酸（DNA）限制性内切酶谱的新方法。用聚合酶链反应(PCR)扩增分枝杆菌hsp65基因的长度为439 bp的片段,该扩增片段经限制性内切酶BstEⅡ和 HaeⅢ酶切后,分别用CE-LIFD装置和常规琼脂糖电泳（AGE）对比检测酶切片段。对PCR扩增片段的酶切样品的预处理和CE条件进行了优化,获得了8种分枝杆菌DNA的限制性内切酶谱图。 DNA片段相对迁移时间的相对标准偏差（RSD）≤3.6%。结果表明,CE的分离效能明显高于AGE,是研究DNA限制性内切酶谱的更有效的检测手段。     

Improved Synthesis of Capuramycin and Its Analogues

Capuramycin and its congeners are considered to be important lead molecules for the development of a new drug for multidrug‐resistant (MDR) Mycobacterium tuberculosis infections. Extensive structure–activity relationship studies of capuramycin to improve the efficacy have been limited because of difficulties in selectively chemically modifying the desired position(s) of the natural product with biologically interesting functional groups. We have developed efficient syntheses of capuramycin and its analogues by using new protecting groups, derived from the chiral (chloro‐4‐methoxyphenyl)(chlorophenyl)methanols, for the uridine ureido nitrogen and primary alcohol. The chiral nonracemic (2,6‐dichloro‐4‐methoxyphenyl)(2,4‐dichlorophenyl)methanol derivative is a useful reagent to resolve rac‐3‐amino‐1,3‐dihydro‐5‐phenyl‐2H‐1,4‐benzodiazepin‐2‐one, the (S)‐configuration isomer of which plays a significant role in improving the mycobactericidal activity of capuramycin.     

Structure-Based Design and Synthesis of Piperidinol-Containing Molecules as New Mycobacterium abscessus Inhibitors

Non-tuberculous mycobacterium (NTM) infections, such as those caused by Mycobacterium abscessus, are increasing globally. Due to their intrinsic drug resistance, M. abscessus pulmonary infections are often difficult to cure using standard chemotherapy. We previously demonstrated that a piperidinol derivative, named PIPD1, is an efficient molecule both against M. abscessus and Mycobacterium tuberculosis, the agent of tuberculosis, by targeting the mycolic acid transporter MmpL3. These results prompted us to design and synthesize a series of piperidinol derivatives and to determine the biological activity against M. abscessus. Structure-activity relationship (SAR) studies pointed toward specific sites on the scaffold that can tolerate slight modifications. Overall, these results identified FMD-88 as a new promising active analogue against M. abscessus. Also, we determined the pharmacokinetics properties of PIPD1 and showed that intraperitoneal administration of this compound resulted in promising serum concentration and an elimination half-life of 3.2 hours.     

Discovery,Synthesis and Evaluation of a Ketol-Acid Reductoisomerase Inhibitor

Ketol-acid reductoisomerase (KARI), the second enzyme in the branched-chain amino acid biosynthesis pathway, is a potential drug target for bacterial infections including Mycobacterium tuberculosis. Here, we have screened the Medicines for Malaria Venture Pathogen Box against purified M. tuberculosis (Mt) KARI and identified two compounds that have K_i values below 200 nm . In Mt cell susceptibility assays one of these compounds exhibited an IC₅₀ value of 0.8 μm . Co-crystallization of this compound, 3-((methylsulfonyl)methyl)-2H-benzo[b][1,4]oxazin-2-one (MMV553002), in complex with Staphylococcus aureus KARI, which has 56 % identity with Mt KARI, NADPH and Mg²⁺ yielded a structure to 1.72 Å resolution. However, only a hydrolyzed product of the inhibitor (i.e. 3-(methylsulfonyl)-2-oxopropanic acid, missing the 2-aminophenol attachment) is observed in the active site. Surprisingly, Mt cell susceptibility assays showed that the 2-aminophenol product is largely responsible for the anti-TB activity of the parent compound. Thus, 3-(methylsulfonyl)-2-oxopropanic acid was identified as a potent KARI inhibitor that could be further explored as a potential biocidal agent and we have shown 2-aminophenol, as an anti-TB drug lead, especially given it has low toxicity against human cells. The study highlights that careful analysis of broad screening assays is required to correctly interpret cell-based activity data.     

Chemometrical analysis of computed QSAR parameters and their use in biological activity prediction

This study gives a quantitative structure-activity relationship (QSAR) correlation of the 72 N-benzylsalicylamide derivatives properties with their antimycobacterial activity. The antimycobacterial activity was measured as the minimal inhibition concentration (MIC) determined for four strains of mycobacterium (M. avium, M. kansasii, M. kansasii clin.-clinically isolated form, and M. tuberculosis) after 14 days and after 21 days of cultivation. The objective was to identify the factors most closely defining biological activity of N-benzylsalicylamides, in order to enable QSAR prediction of new derivatives with high antimycobacterial activity. Optimal properties for the QSAR analysis were selected from several physicochemical properties, including lipophilicity parameter log P, molecular mass M, molar refraction MR, NMR chemical shifts, polarizability, etc. Many of the considered properties are different from those typically used in traditional QSAR. Selection of the most important properties was performed by one-way Analysis of Variance (ANOVA) and correlation analysis using the significance coefficients and the correlation coefficients, respectively. The chosen variables were further used in artificial neural networks (ANN) for predicting biological activity in the form of-log(MIC). Presented at the 1st International Conference “Applied Natural Sciences” on the occasion of the 10th anniversary of the University of Ss. Cyril and Methodius, Trnava, 7–9 November 2007.