Vpliv bioizosterne zamenjave pirazola s triazolom na zaviralno delovanje tetrahidropiranskih zaviralcev InhA

Pirc, Urša (author), Pajk, Stane (mentor)

Tuberkuloza je nalezljiva bolezen, ki jo povzroča bakterija Mycobacterium tuberculosis. V razvitem svetu je večinoma izkoreninjena, vendar kljub terapiji, v manj razvitih državah še vedno povzroča številne smrti. Veliko oviro pri zdravljenju s antituberkulotiki predstavlja naraščajoča pojavnost na zdravila odporne tuberkuloze. Obetajoča tarča antituberkulotikov je zaviranje sinteze mikolnih kislin. Pri sintezi sodeluje FAS II, ki je specifičen le za mikobakterije. Glavni encim sintezne poti FAS II je InhA, NADH odvisna enoil-acil reduktaza, ki reducira dolge verige trans-2-enoil-acil-maščobnih kislin. Struktura InhA vsebuje podenote, ki imajo poleg vezavnega mesta za NADH tudi več alfa in beta zank, kar ustvari hidrofobni žep, v katerega se lahko vežejo lipofilni acil substrati. Izoniazid, zdravilo prvega izbora, učinkovito zavira InhA. Za svoje delovanje potrebuje aktivacijo z encimom Kat G, ki pa je glavni vir rezistence, saj lahko hitro mutira. Spojine, ki bi direktno zavirale encim InhA, bi tako lahko delovale tudi proti rezistentnim sevom. Namen magistrske naloge je bil sintetizirati tetrahidropiranski tip zaviralca InhA, kjer smo pirazolni obroč zamenjali s triazolnim. Triazolne derivate smo sintetizirali z baker(II) katalizirano cikloadicijo azida in alkina, tako imenovano klik reakcijo. Sintetizirani derivati so se med seboj razlikovali po skupini na mestu 4 triazolnega obroča. Izoliranim spojinam smo določali IC50 vrednost na encimu InhA. Samo spojina, ki na četrtem mestu triaziolnega obroča ni imela vezane skupine, je zavirala encim v mikromolarnem območju. Predvidevamo, da je glavni vzrok slabe zaviralne aktivnosti sintetiziranih spojin njihova slaba topnost, saj so se na mikrotitrski ploščici spojine obarjale. S podaljševanjem stranske verige triazolnega obroča, ki ne tvori ključnih interakcij z encimom, ne izboljšamo zaviralne aktivnosti, vplivamo pa na topnost spojin.

• Language: Slovenian
• Keywords: tuberkuloza, direktni zaviralci InhA, klik reakcija
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FFA - Faculty of Pharmacy
• Year: 2022
• PID: 20.500.12556/RUL-143307
• Publication date in RUL: 14.12.2022

Secondary language

• Language: English
• Title: Effect of bioisosteric replacement of pyrazol with triazole on the inhibitory activity of tetrahydropyran type InhA inhibitors

Abstract

Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis. It has been largely eliminated from industrialized countries, but despite therapy still causes many deaths in less developed countries. Growing incidence of drug-resistant tuberculosis poses a major risk for public health. An attractive target for antituberculous drugs is inhibition of the bacterial fatty-acid biosynthesis or FAS pathway. FAS II is specific for Mycobacteria which causes selective toxicity of antibacterial agents. The key enzyme of the FAS II synthesis pathway is InhA, an NADH-dependent enoyl-acyl reductase that facilitates reduction of long-chain trans-2-enoyl-acyl fatty acids. InhA structure contains NADH binding site and several alpha and beta loops, creating a hydrophobic pocket for lipophilic acyl substrates. Isoniazid, first line drug, effectively inhibits InhA. Isoniazid is a prodrug and must be activated by the Kat G enzyme. Mutation of kat G gene is the main source of resistance. Compounds that directly inhibit the InhA enzyme are a promising target for isoniazid resistant strains of bacteria. The objective of the thesis was to synthesize a tetrahydropyran type of InhA inhibitor, where the pyrazole ring was replaced by a triazole ring. Triazole derivatives were synthesized by copper(II) catalyzed cycloaddition of azide and alkyne, the so-called click reaction. The IC50 values were determined for the isolated compounds. Only the compound without the attached group on the triaziol ring showed inhibiting potential in the micromolar range. The compounds precipitated on the microtiter plate therefore the main cause of the poor inhibiting potential is poor solubility of the synthetized compounds. Based on these results we conclude that lengthening the side chain of the triazole ring does not improve the inhibiting potential but can affect the solubility of the compounds.

• Keywords: tuberculosis, direct InhA inhibitors, click reaction