Inhibitor Report for: CHEMBL1818384

Out of the prominent global ailments, tuberculosis (TB) is still one of the leading causes of death worldwide due to infectious disease. Development of new drugs that shorten the current tuberculosis treatment time and have activity against drug resistant strains is of utmost importance. Towards these goals we have focused our efforts on developing novel anti-TB compounds with the general structure of 1-adamantyl-3-phenyl urea. This series is active against Mycobacteria and previous lead compounds were found to inhibit the membrane transporter MmpL3, the protein responsible for mycolic acid transport across the plasma membrane. However, these compounds suffered from poor in vitro pharmacokinetic (PK) profiles and they have a similar structure/SAR to inhibitors of human soluble epoxide hydrolase (sEH) enzymes. Therefore, in this study the further optimization of this compound class was driven by three factors: (1) to increase selectivity for anti-TB activity over human sEH activity, (2) to optimize PK profiles including solubility and (3) to maintain target inhibition. A new series of 1-adamantyl-3-heteroaryl ureas was designed and synthesized replacing the phenyl substituent of the original series with pyridines, pyrimidines, triazines, oxazoles, isoxazoles, oxadiazoles and pyrazoles. This study produced lead isoxazole, oxadiazole and pyrazole substituted adamantyl ureas with improved in vitro PK profiles, increased selectivity and good anti-TB potencies with sub mug/mL minimum inhibitory concentrations.

Adamantyl ureas were previously identified as a group of compounds active against Mycobacterium tuberculosis in culture with minimum inhibitor concentrations (MICs) below 0.1 mug/ml. These compounds have been shown to target MmpL3, a protein involved in secretion of trehalose mono-mycolate. They also inhibit both human soluble epoxide hydrolase (hsEH) and M. tuberculosis epoxide hydrolases. However, active compounds to date have high cLogP's and are poorly soluble, leading to low bioavailability and thus limiting any therapeutic application. In this study, a library of 1600 ureas (mostly adamantyl ureas), which were synthesized for the purpose of increasing the bioavailability of inhibitors of hsEH, was screened for activity against M. tuberculosis. 1-Adamantyl-3-phenyl ureas with a polar para substituent were found to retain moderate activity against M. tuberculosis and one of these compounds was shown to be present in serum after oral administration to mice. However, neither it, nor a closely related analog, reduced M. tuberculosis infection in mice. No correlation between in vitro potency against M. tuberculosis and the hsEH inhibition were found supporting the concept that activity against hsEH and M. tuberculosis can be separated. Also there was a lack of correlation with cLogP and inhibition of the growth of M. tuberculosis. Finally, members of two classes of adamantyl ureas that contained polar components to increase their bioavailability, but lacked efficacy against growing M. tuberculosis, were found to taken up by the bacterium as effectively as a highly active apolar urea suggesting that these modifications to increase bioavailability affected the interaction of the urea against its target rather than making them unable to enter the bacterium.

The treatment of tuberculosis is becoming more difficult due to the ever increasing prevalence of drug resistance. Thus, it is imperative that novel anti-tuberculosis agents, with unique mechanisms of action, be discovered and developed. The direct anti-tubercular testing of a small compound library led to discovery of adamantyl urea hit compound 1. In this study, the hit was followed up through the synthesis of an optimization library. This library was generated by systematically replacing each section of the molecule with a similar moiety until a clear structure-activity relationship was obtained with respect to anti-tubercular activity. The best compounds in this series contained a 1-adamantyl-3-phenyl urea core and had potent activity against Mycobacterium tuberculosis plus an acceptable therapeutic index. It was noted that the compounds identified and the pharmacophore developed is consistent with inhibitors of epoxide hydrolase family of enzymes. Consequently, the compounds were tested for inhibition of representative epoxide hydrolases: M. tuberculosis EphB and EphE; and human soluble epoxide hydrolase. Many of the optimized inhibitors showed both potent EphB and EphE inhibition suggesting the antitubercular activity is through inhibition of multiple epoxide hydrolase enzymes. The inhibitors also showed potent inhibition of humans soluble epoxide hydrolase, but limited cytotoxicity suggesting that future studies must be towards increasing the selectivity of epoxide hydrolase inhibition towards the M. tuberculosis enzymes.

Out of the prominent global ailments, tuberculosis (TB) is still one of the leading causes of death worldwide due to infectious disease. Development of new drugs that shorten the current tuberculosis treatment time and have activity against drug resistant strains is of utmost importance. Towards these goals we have focused our efforts on developing novel anti-TB compounds with the general structure of 1-adamantyl-3-phenyl urea. This series is active against Mycobacteria and previous lead compounds were found to inhibit the membrane transporter MmpL3, the protein responsible for mycolic acid transport across the plasma membrane. However, these compounds suffered from poor in vitro pharmacokinetic (PK) profiles and they have a similar structure/SAR to inhibitors of human soluble epoxide hydrolase (sEH) enzymes. Therefore, in this study the further optimization of this compound class was driven by three factors: (1) to increase selectivity for anti-TB activity over human sEH activity, (2) to optimize PK profiles including solubility and (3) to maintain target inhibition. A new series of 1-adamantyl-3-heteroaryl ureas was designed and synthesized replacing the phenyl substituent of the original series with pyridines, pyrimidines, triazines, oxazoles, isoxazoles, oxadiazoles and pyrazoles. This study produced lead isoxazole, oxadiazole and pyrazole substituted adamantyl ureas with improved in vitro PK profiles, increased selectivity and good anti-TB potencies with sub mug/mL minimum inhibitory concentrations.

New chemotherapeutics active against multidrug-resistant Mycobacterium tuberculosis are urgently needed. We report on the identification of an adamantyl urea compound that shows potent bactericidal activity against M. tuberculosis and a unique mode of action, namely the abolition of the translocation of mycolic acids from the cytoplasm, where they are synthesized to the periplasmic side of the plasma membrane and are in turn transferred onto cell wall arabinogalactan or used in the formation of virulence-associated, outer membrane, trehalose-containing glycolipids. Whole-genome sequencing of spontaneous-resistant mutants of M. tuberculosis selected in vitro followed by genetic validation experiments revealed that our prototype inhibitor targets the inner membrane transporter MmpL3. Conditional gene expression of mmpL3 in mycobacteria and analysis of inhibitor-treated cells validate MmpL3 as essential for mycobacterial growth and support the involvement of this transporter in the translocation of trehalose monomycolate across the plasma membrane.

Adamantyl ureas were previously identified as a group of compounds active against Mycobacterium tuberculosis in culture with minimum inhibitor concentrations (MICs) below 0.1 mug/ml. These compounds have been shown to target MmpL3, a protein involved in secretion of trehalose mono-mycolate. They also inhibit both human soluble epoxide hydrolase (hsEH) and M. tuberculosis epoxide hydrolases. However, active compounds to date have high cLogP's and are poorly soluble, leading to low bioavailability and thus limiting any therapeutic application. In this study, a library of 1600 ureas (mostly adamantyl ureas), which were synthesized for the purpose of increasing the bioavailability of inhibitors of hsEH, was screened for activity against M. tuberculosis. 1-Adamantyl-3-phenyl ureas with a polar para substituent were found to retain moderate activity against M. tuberculosis and one of these compounds was shown to be present in serum after oral administration to mice. However, neither it, nor a closely related analog, reduced M. tuberculosis infection in mice. No correlation between in vitro potency against M. tuberculosis and the hsEH inhibition were found supporting the concept that activity against hsEH and M. tuberculosis can be separated. Also there was a lack of correlation with cLogP and inhibition of the growth of M. tuberculosis. Finally, members of two classes of adamantyl ureas that contained polar components to increase their bioavailability, but lacked efficacy against growing M. tuberculosis, were found to taken up by the bacterium as effectively as a highly active apolar urea suggesting that these modifications to increase bioavailability affected the interaction of the urea against its target rather than making them unable to enter the bacterium.

The treatment of tuberculosis is becoming more difficult due to the ever increasing prevalence of drug resistance. Thus, it is imperative that novel anti-tuberculosis agents, with unique mechanisms of action, be discovered and developed. The direct anti-tubercular testing of a small compound library led to discovery of adamantyl urea hit compound 1. In this study, the hit was followed up through the synthesis of an optimization library. This library was generated by systematically replacing each section of the molecule with a similar moiety until a clear structure-activity relationship was obtained with respect to anti-tubercular activity. The best compounds in this series contained a 1-adamantyl-3-phenyl urea core and had potent activity against Mycobacterium tuberculosis plus an acceptable therapeutic index. It was noted that the compounds identified and the pharmacophore developed is consistent with inhibitors of epoxide hydrolase family of enzymes. Consequently, the compounds were tested for inhibition of representative epoxide hydrolases: M. tuberculosis EphB and EphE; and human soluble epoxide hydrolase. Many of the optimized inhibitors showed both potent EphB and EphE inhibition suggesting the antitubercular activity is through inhibition of multiple epoxide hydrolase enzymes. The inhibitors also showed potent inhibition of humans soluble epoxide hydrolase, but limited cytotoxicity suggesting that future studies must be towards increasing the selectivity of epoxide hydrolase inhibition towards the M. tuberculosis enzymes.