Sinteza novih zaviralcev bakterijske DNA giraze A z 1,5-naftiridinskim skeletom

Kokot, Maja (author), Anderluh, Marko (mentor)

Protibakterijska zdravila so ena najpogosteje predpisanih in uporabljenih zdravil. Dolgotrajna prepogosta in nepremišljena uporaba je pripeljala do pojava bakterijske odpornosti ter zmanjšanja učinkovitosti do sedaj obstoječih protibakterijskih zdravil. Zaradi razvijajoče se odpornosti raste potreba po iskanju novih tarč oz. načrtovanju in razvoju novih zdravil. Ena izmed novejših skupin protibakterijskih zdravil so tudi tako imenovani novi zaviralci podenote A bakterijske DNA giraze (NBTI). Kot že samo ime pove, gre za zaviralce DNA giraze. Gre za esencialni encim, ki kontrolira in vzdržuje topološko stanje molekule DNA v celici. Ima posebno zmožnost uvajanja negativnih supernavojev v verigo DNA v prisotnosti ATP. Z vezavo NBTI-ja v aktivno mesto encima zavremo delovanje DNA giraze in onemogočimo proces podvojevanja ali prepisovanja DNA. NBTI so sestavljeni iz 3 delov: biciklični levi del (LHS), distančnik in aromatski desni del (RHS). V sklopu magistrske naloge smo se osredotočili na sintezo novih zaviralcev bakterijske DNA giraze A z 1,5-naftiridinskim skeletom. Pri tem smo ohranili levi del molekule ter distančnik in spreminjali le desni del molekule, ki je ključen za vezavo učinkovine med podenoti A DNA giraze. Sistem dela je bil sestavljen iz dveh delov. Najprej smo naredili prvo serijo spojin. Nato pa je sledilo načrtovanje na osnovi optimizacije najboljše spojine iz prve serije. Druga serija je potekala v smeri halogenih interakcij. Želeli smo dokazati, da lahko z uvedbo halogenov na specifično mesto v strukturi dosežemo močnejše delovanje zaradi dodatne halogene interakcije. Končnim spojinam smo določili IC50, ki je merilo jakosti učinkovine in predstavlja koncentracijo učinkovine, ki zmanjša aktivnost encima na 50 % najvišje aktivnosti encima DNA giraze ter MIC, ki je minimalna inhibitorna koncentracija in predstavlja najnižjo koncentracijo učinkovine, ki še zavira rast preiskovane bakterije. Biološka testiranja so potrdila naše napovedi. V primeru halogenov na mestu para so vrednosti IC50 in MIC po homologoni vrsti navzdol upadale, iz česar lahko sklepamo, da je za povečano jakost odgovorna halogena vez med halogenom in kisikom Ala86.

• Language: Slovenian
• Keywords: DNA giraza A, zaviralci, NBTI, DNA, topoizomeraza
• Work type: Master's thesis/paper
• Organization: FFA - Faculty of Pharmacy
• Year: 2019
• PID: 20.500.12556/RUL-109909
• Publication date in RUL: 10.09.2019

Secondary language

• Language: English
• Title: Synthesis of novel DNA Gyrase A inhibitors with 1,5-naphthyridine scaffold

Abstract

Antibacterial drugs are one of the most common prescribed and used drugs. Long-term, to common and reckless antibiotic use is the reason of the bacterial resistance appearance and effectiveness decrease up to now existing antibacterial drugs. Due to the developing resistance, there is a need to research new targets and develop new drugs. One of the newest antibacterial drugs are so-called novel bacterial topoisomerase inhibitors (NBTIs). They are inhibitors of bacterial DNA gyrase. DNA gyrase is essential enzyme, that control and maintain the topological state of the DNA in the cell. It has the ability to introduce negative supercoils into DNA in the presence of ATP. By binding NBTI in active site of the enzyme, we inhibit DNA gyrase and disable DNA translation and transcription. NBTIs are composed of 3 parts: bicyclic left-hand side (LHS), the linker and an aromatic right-hand side (RHS). Within the framework of the master's degree we focused on the synthesis of novel DNA Gyrase A inhibitors with 1,5-naphthyridine scaffold. We kept left side and the linker and changed just the right side, that binds to the GyrA subunits. Our work system consists of two parts. First, we have synthesized and evaluated one series of compounds. In the next step the optimization of the most potent compound from the first series has followed. The second series was designed to reach the presumable halogen interaction, which we deemed important based on docking results. We wanted to prove, that with introduction of halogens we can reach more potent compounds because of additional halogen interaction. We have evaluated compound’s potency by determining their IC50 that is a measure of the potency of active substance and represent the concentration of the active substance, that decrease enzyme activity on 50% the highest activity of DNA gyrase and MIC, that is minimal inhibitory concentration and present the lowest concentration of active substance, that inhibit grow of bacterium. Biological assays confirmed our hypothesis. In case of halogen on para position, were decreasing IC50 and MIC values by homologues row. We can assume, that halogen bond between halogen atom and enzyme oxygen is responsible for the increased potency.

• Keywords: GyrA, inhibitors, NBTIs, DNA topoisomerase