Sinteza in vrednotenje tiazolnih zaviralcev encima MurA

Pogačnik, Jerneja (author), Pajk, Stane (mentor), Hrast, Martina (co-mentor)

Kljub odkritju in uspešnemu razvoju protibakterijskih učinkovin, učinkovitost zdravljenja bakterijskih okužb vztrajno pada. Glavni razlog pripisujemo razvoju odpornosti bakterijskih sevov na posamezne protibakterijske učinkovine. V klinični uporabi je širok nabor protibakterijskih zdravilnih učinkovin, a je potreba po razvoju antibiotikov z novim mehanizmom delovanja zelo velika. Zanimivo in obetavno področje razvoja predstavljajo bakterijski encimi, ki sodelujejo pri sintezi glavnega gradnika celične stene, to je peptidoglikana. Z zaviranjem sinteze peptidoglikana tako sprožimo celično smrt. Prednost tega mehanizma delovanja je selektivna toksičnost, zaviramo zgolj rast bakterijske celice, saj peptidoglikan v človeški celici ni prisoten. MurA (UDP-N-acetilglukozamin enolpiruvil transferaza) je encim, ki sodeluje v prvi stopnji sinteze peptidoglikana, v klinični uporabi pa je zdravilna učinkovina fosfomicin, ki ga uspešno zavira. V sklopu magistrske naloge smo sintetizirali nove potencialne zaviralce MurA encima. Izhajali smo iz šestih derivatov 2-aminotiazola, iz katerih smo pripravili 2-bromotiazolne derivate. Nato smo iz različnih bromotiazolov sintetizirali osem derivatov 2-viniltiazolov in poskusili s sintezo 2-jodotiazola. Pridobljenim spojinam smo z biokemijskim testiranjem določili zaviralno delovanje na MurA iz Escherichia coli. Najmočnejše zaviralno delovanje je izkazalo šest sintetiziranih spojin (2, 5, 7, 11, 16 in 23). Te so zavirale encim v nizkem mikromolarnem območju, rezidualna aktivnost spojin je bila nižja od 50 % pri koncentraciji 500 µM. Najmočneje je delovala spojina 23 (IC50 = 70 µM), z vinilno skupino na mestu 2 in karboksilno skupino na mestu 4. Sledijo ji bromidni derivati, najbolje je delovala spojina 2 (IC50 = 85 µM) s terc-butilno skupino in spojina 11 (IC50 = 141 µM) z metilno skupino na mestu 4 in karboksilno skupino na mestu 5. Dobro zaviralno delovanje je izkazala še spojina 16 (IC50 = 471 µM) z vinilno skupino na mestu 2 in karboksilatom na mestu 4. Ugotovili smo, da sta tako vinilna kot bromidna skupina ključni za zaviralno delovanje spojine, najmočnejši zaviralec pa je bil derivat 2-viniltiazolna (spojina 23). Velik vpliv na delovanje so imele na tiazolni obroč vezane stranske funkcionalne skupine, zaradi katerih so se bromotiazoli (2, 5, 7, 11) izkazali kot dobri encimski zaviralci. Spojini 23 in 2 predstavljata potencialno dobro izhodišče za razvoj močnejših in selektivnejših zaviralcev encima MurA.

• Language: Slovenian
• Keywords: MurA encim, bromotiazoli, vinitiazoli, peptidoglikan, protibakterijske učinkovine.
• Work type: Master's thesis/paper
• Organization: FFA - Faculty of Pharmacy
• Year: 2021
• PID: 20.500.12556/RUL-129904
• Publication date in RUL: 09.09.2021

Secondary language

• Language: English
• Title: Synthesis and evaluation of thiazole-based MurA inhibitors

Abstract

Successful development of antibacterial agents and the effectiveness of treatment of bacterial infections is steadily declining. The main reason is development of bacterial resistance to individual antibacterial agents. There is a wide range of antibacterial drugs in clinical use, nevertheless new drugs with novel mechanisms of action are required. Interesting and promising field for development of new antibacterial are bacterial enzymes involved in the synthesis of the main building block of the cell wall, peptidoglycan. By inhibiting peptidoglycan synthesis, cell death is thus triggered. The main advantage of this mechanism of action is selective toxicity, which means that inhibition occurs only in bacterial cells, as peptidoglycan is not present in the human cell. MurA (UDP-N-acetylglucosamine enolpiruvyl transferase) is an enzyme involved in the first stage of peptidoglycan synthesis. The therapeutically effective drug in clinical use is phosphomycin. In this master's thesis we synthesized new potential inhibitors of the MurA enzyme. The starting points were 2-aminothiazole derivatives from which we synthesized 2-bromothiazoles. Then we exchanged the bromide atom with the vinyl group and one with an iodine atom. The inhibitory activity of the obtained compounds was determined by using biochemical assays on MurA from Escherichia coli. Six compounds (2, 5, 7, 11, 16 in 23) showed the most potent inhibitory effect. They inhibited the enzyme in the low micromolar range and the residual activities of the compounds were lower than 50% at a concentration of 500 µM. Compound 23 (IC50 = 70 µM) had the strongest effect, with a vinyl group at position 2 and a carboxyl group at position 4. Compounds 2 (IC50 = 85 µM) and 11 ( IC50 = 141 µM) both with the bromide atom in the position 2 on the thiazole ring were identified as potent inhibitors. Compound 16 (IC50 = 471 µM) with a vinyl group at position 2 also showed promising inhibitory activity. In conclusion, both the vinyl group and bromide atom were crucial for the inhibitory action of the compound, nevertheless the 2-vinylthiazole derivative (compound 23) proved to be the most potent inhibiotr of MurA. Side groups attached on thiazole showed a large impact on inhibition, which proved that bromothiazoles (2, 5, 7, 11) are good enzyme inhibitors. Compounds 23 and 2 represent a good starting point for the development of stronger and more selective MurA enzyme inhibitors.

• Keywords: MurA enzyme, bromothiazoles, vinylthiazoles, peptidoglycan, antibacterial agents.