Design, synthesis and evaluation of covalent thiazole-based inhibitors of MurA ligase and monoamine oxidases

Odkritje protibakterijskih učinkovin v začetku dvajsetega stoletja je drastično izboljšalo kakovost življenja in omogočilo razvoj moderne medicine. Pretirana in prepogosta uporaba protibakterijskih učinkovin je nato privedla do pospešenega razvoja odpornosti bakterij in predstavlja grožnjo javnemu zdravju in vrnitvi v obdobje pred odkritjem antibiotikov. Med potencialnimi tarčami za razvoj novih protibakterijskih učinkovin je peptidoglikan, ki gradi bakterijsko celično steno. Encim MurA je ključni encim, ki katalizira prvo stopnjo biosinteze peptidoglikana. Monoaminske oksidaze (MAO) so encimi, ki katalizirajo reakcijo oksidativne deaminacije monoaminov. Njihovi zaviralci se uporabljajo pri terapiji Parkinsonove bolezni, Alzheimerjeve bolezni in ostalih nevrodegenerativnih bolezni, ki predstavljajo velik izziv pri odkrivanju uspešnega zdravljenja. V sklopu laboratorijskega dela smo s pomočjo molekulskega sidranja in predhodno sintetiziranih derivatov tiazola načrtovali in sintetizirali nove spojine. Izhajali smo iz 5-bromotiazola oziroma tiazol-5-karbonitrila, na katera smo preko dušika na mestu 2 vezali različne funkcionalne skupine. Z biološkim testiranjem smo ugotavljali ali s pripenjanjem kislih funkcionalnih skupin izboljšamo njihovo zaviralno aktivnost na encimu MurA. Selektivnost delovanja spojin smo preverili še na encimih MAO-A in MAO-B. Uspešnost zaviranja encima MurA smo primerjali z izhodnimi spojinami in spojinama vodnicama a in b z znanim zaviralnim delovanjem. V primerjavi z izhodnimi spojinami smo zaviralno aktivnost povečali, spojine 12, 23 in 26 pa so imele boljše zaviranje kot spojini vodnici. Ugotovili smo, da imajo spojine z vezano karboksilno kislino boljšo zaviralno delovanje v primerjavi z estri. Vse aktivne spojine so selektivne za encim MurA, saj ni nobena izkazovala zaviralnega delovanja na izoencimih MAO. Sintetizirani derivati tiazola s pripetimi kislimi substrati predstavljajo dobro izhodišče za nadaljnje optimizacije zadetkov, ki bodo kovalentno zavirali encim MurA. Zaradi tega predstavlja naše delo pomemben prispevek k razvoju novih protibakterijskih učinkovin.The discovery of antibacterial agents at the beginning of the 20th century drastically improved the quality of life and enabled the development of modern medicine. The excessive and overuse of antibacterial agents has led to the accelerated emergence of antibiotic resistance in pathogenic bacteria. This poses a threat to public health and a return to the pre-antibiotic era. One of the potential targets for the development of new antibacterial agents is peptidoglycan, which builds the bacterial cell wall. The MurA enzyme is a key enzyme that catalyzes the first step of peptidoglycan biosynthesis. Monoamine oxidases (MAOs) are enzymes that catalyze the oxidative deamination of monoamines. Their inhibitors are used in the therapy of Parkinson’s disease, Alzheimer’s disease, and other neurodegenerative diseases, that pose a major challenge in finding a successful treatment. Using docking and previously synthesized thiazole derivatives, we designed and synthesized novel compounds and evaluated their inhibitory effects on MurA. In addition, their inhibitory effect on the enzymes MAO-A and MAO-B was assayed to confirm their selectivity for the enzyme MurA. We started from a thiazole to which a bromine or carbonitrile was attached at position 5 and various functional groups were attached via nitrogen at position 2. Through biological assays we determined whether the attachment of acidic groups improved inhibitory activity. The efficacy of inhibition of the MurA enzyme was compared with parent and lead compounds with known inhibitory activity. Inhibitory activity has been improved in comparison with parent compounds, while compounds 12, 23 and 26 were more active than the lead. We demonstrated that the binding of carboxylic acid and its esters improved the inhibitory activity compared to previously tested thiazole derivatives. All synthesized compounds are selective for the MurA enzyme, as none of them sufficiently inhibits the MAO isoenzymes. The synthesized thiazole derivatives with attached acidic substrates represent a good starting point for further optimization of hits, that covalently inhibit MurA enzyme to develop new potential antibacterial agents