Sinteza etilsečninskih derivatov 2-aminotiazola kot potencialnih zaviralcev DNA-giraze : enoviti magistrski študij farmacije

Nartnik, Aleš (avtor), Tomašič, Tihomir (mentor)

Pojav odpornosti proti protibakterijskim učinkovinam se nezadržno širi in je že postal problem globalnih razsežnosti, zato farmacevtska industrija pospešeno raziskuje nove potencialne tarče in razvija nove protibakterijske učinkovine. Širjenje »superbakterij«, ki so razvile odpornost proti prav vsem terapevtsko uporabnim protibakterijskim učinkovinam, nas je prisililo v razvoj protibakterijskih učinkovin, ki imajo edinstven mehanizem delovanja. DNA-giraza ima v bakterijski celici pomembno biološko funkcijo, saj sodeluje pri podvajanju molekul DNA in ima edinstveno sposobnost uvajanja dodatnih negativnih zavojev v krožno molekulo DNA. Strukturna podobnost s topoizomerazo IV, ki je prav tako udeležena v uravnavanju topologije in podvajanju molekul DNA, nam odpira možnost dvojnega tarčnega ciljanja. Zaradi njene biološke funkcije, možnosti dvojnega tarčnega ciljanja in dejstva, da DNA-girazo najdemo samo v prokariontskih organizmih, je zanimiva tarča za razvoj novih protibakterijskih učinkovin. V okviru magistrskega dela smo sintetizirali etilsečninske derivate 2-aminotiazola kot potencialne zaviralce DNA-giraze. Za etilsečninski fragment, vezan na amino skupino 2-aminotiazola, je dokazano, da je sposoben ključnih interakcij z Asp73 in s strukturno ohranjeno molekulo vode, zato smo z uvedbo različnih dodatnih substituentov skušali izboljšati fizikalno-kemijske lastnosti načrtovanih spojin. Izhajali smo iz treh različnih izhodnih spojin, zato smo sintetizirali tri različne serije potencialnih zaviralcev s 4,5,6,7-tetrahidrobenzo[1,2-d]tiazolnim, z benzo[1,2-d]tiazolnim in s tiazolnim skeletom. Najboljšo encimsko zaviralno aktivnost je imel derivat pirolamida 6 (IC50 = 1,4 μM), pri katerem ključne interakcije z Asp73 tvori pirolamidni fragment, ki glede na kristalne strukture kompleksov DNA-giraze in zaviralcev tvori eno vodikovo vez manj od etilsečninskega fragmenta. Pri spojinah s tetrahidrobenzo[1,2-d]tiazolnim in s tiazolnim osrednjim skeletom je bil razlog za šibko encimsko zaviralno aktivnost najverjetneje odsotnost kation-π interakcij z Glu50-Arg76 solnim mostom. Serija zaviralcev z nenasičenim benzo[1,2-d]tiazolnim skeletom, ki je teh interakcij sposobna, izkazuje do 90-krat boljšo encimsko aktivnost od nenasičenih analogov (IC50 = 3,9 μM proti 350 μM). Protibakterijsko testiranje spojin je pokazalo zelo šibko delovanje na po Gramu-pozitivne in neaktivnost na po Gramu-negativne bakterije. Razloga za slabo protibakterijsko delovanje sta verjetno prešibka encimska zaviralna aktivnost in to, da so spojine substrat za celične izlivne črpalke, ki znižujejo citoplazemsko koncentracijo v bakterijskih celicah, in ne slaba permeabilnost.

• Jezik: Slovenski jezik
• Ključne besede: bakterijska odpornost etilsečnine 2-aminotiazol protibakterijske učinkovine topoizomeraza IV
• Vrsta gradiva: Magistrsko delo/naloga
• Tipologija: 2.09 - Magistrsko delo
• Organizacija: FFA - Fakulteta za farmacijo
• Kraj izida: Ljubljana
• Založnik: [A. Nartnik]
• Leto izida: 2017
• Št. strani: XIV, 63 f.
• PID: 20.500.12556/RUL-120507
• UDK: 615.015.8:543.057(043.3)
• COBISS.SI-ID: 4324977
• Datum objave v RUL: 21.09.2020

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Synthesis of ethylurea derivatives of 2-aminothiazole as potential inhibitors of DNA-gyrase

Izvleček

The antibiotic resistance phenomenon which is uncontrollably spreading worldwide has already become a problem of global dimensions and as such gives pharmaceutical industry all the more reasons to investigate new potential antibacterial targets and develop new antibacterial agents. Emerging “superbugs” which have developed resistance against all known antibacterial agents has forced us into development of antibacterial agents with a unique mechanism of action. DNA gyrase has an important biological role in process of DNA replication and has unique ability of introducing negative supercoils into circular DNA. Structural similarity with topoisomerase IV, which is also involved in modulation of DNA topology and DNA replication, opens a possibility of dual targeting of both enzymes. Its biological role, possibility of dual targeting and the fact that it is only present in prokaryotes make DNA gyrase an interesting target for development of new antibacterial agents. Within this master’s thesis we synthesized ethylurea derivatives of 2-aminothiazole as potential inhibitors of DNA gyrase. Since it is proven that ethylurea moiety can form key interactions with Asp73 and a bound water molecule we have introduced different substituents to improve physical and chemical properties of designed compounds. We originated from three starting compounds and as a result we have synthesized three different series of potential inhibitors with 4,5,6,7-tetrahydrobenzo[1,2-d]thiazole, benzo[1,2-d]thiazole and thiazole as a central rings. The best inhibitory activity displayed pyrrolamide 6 (IC50 = 1,4 μM) of which, in spite of forming one hydrogen bond less than ethylurea moiety, it is pyrrolamide moiety that anchors the inhibitor in ATP binding site of DNA gyrase. The main reason for weak inhibitory activity of series with 4,5,6,7-tetrahydrobenzo[1,2-d]thiazole and thiazole central rings was inability of forming cation-π interactions between Glu50-Arg76 salt bridge and inhibitors. Series of inhibitors with unsaturated central rings which can form such interaction have shown 90-fold more potent inhibitory activity than their saturated analogs (IC50 = 3,9 μM against 350 μM). Antibacterial testing has shown weak antibacterial activity against Gram-positive bacteria and inactivity against Gram-negative bacteria. Additional testing indicated that these compounds are efflux pump substrates, thus reducing their cytoplasmic concentrations as the main reason for weak antibacterial activity or the lack of it, and not their penetration through cell wall.

• Ključne besede: ethylurea 2-aminothiazole DNA gyrase topoisomerase IV antibacterial