Načrtovanje in sinteza C-1 substituiranih derivatov glukozamina kot zaviralcev encima MurA

Goljevšček, Sara (author), Frlan, Rok (mentor)

Pojav odpornosti bakterij na že odkrite protibakterijske učinkovine predstavlja vedno večji problem v zdravstvu, zato je razvoj novih učinkovin ključnega pomena pri boju z odpornostjo. Biosinteza peptidoglikana, ki je prisoten samo v bakterijski celični steni in je nujen za preživetje bakterij, je že dolgo tarča delovanja različnih protibakterijskih učinkovin. Še posebej zanimiva tarča so encimi Mur, ki sodelujejo v začetnih stopnjah biosinteze peptidoglikana, a je trenutno kot zaviralec omenjenih encimov na voljo le fosfomicin, zato ti encimi predstavljajo pomembno tarčo pri nadaljnjem razvoju protibakterijskih učinkovin. Namen magistrske naloge je bila sinteza zaviralcev encima MurA, pri čemer smo izhajali iz N-acetilglukozamina in poskušali pripraviti spojine z modifikacijami na mestu C-1, ki bi izkazovale dobro zaviralno delovanje na MurA v bakteriji Escherichia coli. Želeli smo čim bolj posnemati naravni substrat UDP-N-acetilglukozamin, tako da smo uporabili N-acetilglukozamin za ustrezno usmerjenost funkcionalnih skupin in lažje prehajanje bakterijske celične stene in s pripravo spojin z lipofilnimi fragmenti, ki bi se dobro vezale v aktivno mesto encima. Načrtovali smo sintezo osmih končnih spojin iz N-acetilglukozamina, kateremu smo najprej zaščitili vse hidroksilne skupine, razen skupine na mestu C-1. Na to mesto smo nato pripeli različne substituente. Med končnimi spojinami so imele tri spojine amidno vez in štiri spojine triazol, pri čemer sta imeli obe skupini vezane različne substituente. Dobljenim vmesnim produktom smo na koncu odstranili acetilne zaščitne skupine z bazično hidrolizo in dobili smo sedem končnih spojin, pri eni izmed spojin pa je bila hidroliza neuspešna in je nismo uspeli sintetizirati. Končnim spojinam smo tudi ovrednotili zaviralno aktivnost s pomočjo bioloških testov in od vseh spojin je imela spojina 5 rezidualno aktivnost 38 %, zato smo ji določili IC50, ki je znašal 502 μM. Z optimizacijo spojine 5 bi lahko prišli še korak bližje sintezi novega zaviralca encima MurA, zato pričakujemo, da bo imelo naše delo pomembno vlogo pri razvoju novih zaviralcev MurA in bo prispevalo k ustvarjanju novih protibakterijskih učinkovin, ki bodo delovale na odporne seve.

• Language: Slovenian
• Keywords: encim MurA, N-acetilglukozamin, odpornost, peptidoglikan, protibakterijske učinkovine
• Work type: Master's thesis/paper
• Organization: FFA - Faculty of Pharmacy
• Year: 2024
• PID: 20.500.12556/RUL-158274
• Publication date in RUL: 01.06.2024

Secondary language

• Language: English
• Title: Design and synthesis of C-1 substituted glucosamine derivatives as MurA enzyme inhibitors

Abstract

Bacterial resistance to already discovered antibacterial agents is becoming an ever-increasing problem in healthcare. Crucial steps in the fight against resistance are taken with the development of new antibacterial agents. The biosynthesis of peptidoglycan, present only in the bacterial cell wall and essential for bacterial survival, has been a target of various antibacterial agents for a long time. Particularly interesting targets are the Mur enzymes involved in the initial stages of biosynthesis. Currently, only fosfomycin is available, therefore the Mur enzymes provide substantial opportunities for further antibacterial substance development. The purpose of the master's thesis was the synthesis of MurA enzyme inhibitors deriving from N-acetylglucosamine. We attempted to create compounds with modifications at the C-1 position that would exhibit good inhibitory activity on MurA in Escherichia coli bacteria. Our goal was to mimic the natural substrate UDP-N-acetylglucosamine as closely as possible. We aimed to achieve this objective by using N-acetylglucosamine for the suitable orientation of functional compounds, facilitating their passage through the bacterial cell wall and by producing compounds with lipophilic fragments that could bind well to the enzyme's active site. We planned the synthesis of 8 final compounds derived from N-acetylglucosamine by at first protecting all of its hydroxyl groups except the one at the C-1 position. By attaching various substituents to this position, we created 3 compounds that had an amide bond and 4 compounds that had a triazole bond, with both groups having different substituents bound. Acetyl protecting groups were removed from the obtained intermediate products at the end through basic hydrolysis, resulting in 7 final compounds. However, hydrolysis was unsuccessful for one of the compounds, and we were unable to synthesize it. We evaluated the inhibitory activity of the final compounds by means of biological testing. Only compound 5 exhibited the residual activity of 38%. We determined its IC50 value, which amounted to 502 μM. By optimizing compound 5, we could come one step closer to synthesizing a new inhibitor of the enzyme MurA. Therefore, we expect that our work will play an important role in the development of new MurA inhibitors and will contribute to the creation of new antibacterial agents that act on resistant strains.

• Keywords: antibacterial agents, MurA enzyme, N-acetylglucosamine, peptidoglycan, resistance