Sinteza, karakterizacija in biokemijsko vrednotenje delno nasičenih derivatov nitroksolina

Virant, Matej (author), Sosič, Izidor (mentor)

Nitroksolin je znana protibakterijska učinkovina, za katero je bilo odkritih več sekundarnih indikacij, izmed katerih velja izpostaviti zaviranje katepsina B in MetAP2. Omenjena encima pri prekomernem izražanju in preveliki katalitični aktivnosti sodelujeta pri progresiji številnih bolezni. Sintetizirali, karakterizirali in biokemijsko smo ovrednotili štiri delno nasičene in nitrirane derivate nitroksolina. Izhajali smo iz 8-hidroksikinolina, mu delno nasitili kinolinski obroč in nato na različna mesta uvedli nitro skupino. Za substitucijo na meta mesto smo izvedli večstopenjsko sintezo. Najprej smo acetilirali aminsko in hidroksilno skupino, nato selektivno odščitili hidroksilno skupino ter zatem izvedli še regioselektivno nitriranje. Temu je sledila še odščita aminske skupine. Vse spojine smo ovrednotili v smislu protibakterijskega delovanja ter preverili zmožnost zaviranja katepsina B in MetAP2. Medsebojno smo primerjali, kateri izmed pripravljenih derivatov ima dobro protibakterijsko delovanje in kateri uspešneje zavira oba encima, nato pa smo vrednosti primerjali še z nitroksolinom. Endopeptidazno aktivnost katepsina B najbolje zavirata spojini 6 in 9, vendar slabše kot nitroksolin. Pri zaviranju eksopeptidazne aktivnost katepsina B sta se kot najboljši pokazali spojini 6 in 9, ki hkrati delujeta tudi bolje od nitroksolina. Spojina 8 sicer dobro zavira MetAP2, a slabše kot nitroksolin. Tudi protibakterijsko delovanje je daleč najboljše pri nitroksolinu v primerjavi z vsemi sintetiziranimi spojinami. Vzrok slabšega delovanja je strukturna sprememba molekule, in sicer delno nasičenje kinolinskega obroča, kar ima precejšnje funkcionalne posledice. Pride namreč do preprečitve zmožnosti kelacije dvovalentnih kationov med dušikom na kinolinskem obroču in hidroksilno skupino. Kljub temu smo lahko z rezultati zadovoljni, saj smo pridobili derivate, ki imajo nizko molekulsko maso in še vedno ohranjajo sposobnost zaviranja obeh encimov. Tako predstavljajo dobre izhodiščne točke za morebitno nadaljnjo optimizacijo.

• Language: Slovenian
• Keywords: nitroksolin, derivati ​​nitroksolina, nasičeni derivati, sekundarne indikacije, katepsin B, metionin aminopeptidaza 2, polifarmakologija
• Work type: Master's thesis/paper
• Organization: FFA - Faculty of Pharmacy
• Year: 2020
• PID: 20.500.12556/RUL-114820
• Publication date in RUL: 14.03.2020

Secondary language

• Language: English
• Title: Synthesis, characterization and biochemical evaluation of partly saturated nitroxoline derivatives

Abstract

Nitroxoline is a known antibacterial drug for which secondary indications were discovered. Namely, nitroxoline can inhibit cathepsin B and MetAP2 in the low micromolar and nanomolar range, respectively. Overexpression and aberrant activity of these two enzymes has been implicated in many processes which are related to pathological conditions. Four partly saturated and nitrated nitroxoline derivatives were synthesized, characterized and evaluated biochemically. The starting compound for the synthesis was 8-hydroxyquinoline which was first partially reduced, resulting in ring saturation. The nitro group was then introduced at various positions on the partly saturated quinoline ring. To achieve substitution at the meta position several synthetic steps were performed. First, the acetylation to protect the amino and hydroxyl group was performed, then the hydroxyl group was selectively deprotected. Finally, the regioselective nitration was performed, followed by the removal of the protection of amino group. We assayed the compounds for antibacterial activity and on both enzymes, i.e cathepsin B and MetAP2. We compared the results for all newly prepared compounds with the values known for nitroxoline. Compounds 6 and 9 showed the best inhibition of the endopeptidase activity of cathepsin B, which was not better than determined for nitroxoline. However, both 6 and 9 did inhibit the exopeptidase activity of cathepsin B better than nitroxoline. Compound 8 was proved as the most promising MetAP2 inhibitor, albeit it was less effective than nitroxoline. Also, the antibacterial activity is by far the best for nitroxoline in comparison with the synthesized compounds. Most probably, the underlying cause of worse inhibition is the structural change introduced by partial saturation. These compounds loose their ability to chelate bivalent cations between the quinoline nitrogen and the hydroxyl group. Nevertheless, the results are encouraging, because the prepared compounds retain inhibitory properties in the micromolar range, which renders these derivatives as good starting point for further medical chemistry optimization.

• Keywords: nitroxoline, nitroxoline derivatives, saturated derivatives, secondary indications, cathepsin B, methionine aminopeptidase 2, polypharmacology