Sinteza disubstituiranih 1,2,4-oksadiazolnih zaviralcev človeške DNA topoizomeraze IIα

Velikanje, Melita (author), Sollner Dolenc, Marija (mentor), Perdih, Andrej (co-mentor)

Rak je skupina bolezni, za katere je značilno nekontrolirano deljenje celic. Encim človeška DNA topoizomeraza IIα je uveljavljena tarča pri zdravljenju rakavih obolenj, saj katalizira topološke spremembe v molekuli DNA in je tako nujno potreben encim za uspešen potek celične delitve. Z vezavo majhnih organskih spojin lahko delovanje encima zavremo ter tako tudi preprečimo delitev rakavih celic. Zaviralce človeške DNA topoizomeraze IIα delimo na topoizomerazne strupe ter katalitične zaviralce. Zaradi neželenih učinkov topoizomeraznih strupov, ki se uporabljajo v klinični praksi, predvsem kardiotoksičnosti in indukcije sekundarnih rakavih obolenj, je vse večja težnja po razvoju novih katalitičnih zaviralcev. V magistrski nalogi smo na osnovi do sedaj poznanega odnosa med strukturo in delovanjem kemijskega razreda 3,5-disubstituiranih 1,2,4-oksadiazolov, ki delujejo kot katalitični zaviralci topoizomeraze IIα in se vežejo v ATP vezavno mesto encima, sintetizirali 11 novih analogov. Pridobili pa smo še 6 komercialno dostopnih derivatov, ki so strukturno podobni sintetiziranim spojinam. Zaviralno aktivnost vseh spojin smo ovrednotili z in vitro testom relaksacijske encimske aktivnosti topo IIα. Sintetizirani derivati niso izboljšali zaviralne aktivnosti v primerjavi s spojinami, ki so bile že sintetizirane v sklopu predhodnih raziskav. Izmed ovrednotenih komercialno dostopnih spojin je spojina 44 pri testiranju izkazala obetavne rezultate. Ta rezultat nakazuje, da uvedba lipofilnih fragmentov na fenilni obroč, ki ima vezano acetamidno skupino, ugodno vpliva na zaviralni učinek 3,5-disubstituiranih 1,2,4-oksadiazolov. Za aktivno spojino 44 smo pokazali tudi, da spada v skupino katalitičnih zaviralcev in da zmanjša spodbujanje cepitve, ki jo povzroča topoizomerazni strup etopozid, ter tako deluje preko drugega mehanizma. Molekulsko sidranje je nakazalo, da je tvorba dodatnih hidrofobnih interakcij med metilno skupino in preostanki v ATP vezavnem mestu možen razlog za opaženo boljšo topo IIα zaviralno aktivnost te spojine. S pridobljenimi rezultati smo razširili poznavanje odnosa med strukturo in delovanjem 3,5-disubstituiranih 1,2,4-oksadiazolov kot katalitičnih zaviralcev človeške topoizomeraze IIα ter pridobili koristne informacije za nadaljnji razvoj te skupine potencialnih protirakavih učinkovin do spojin, ki bi imele primerljivo učinkovitost kot klinično uporabni topoizomerazni II strupi ter bi sočasno izkazovale manjšo pojavnost neželenih učinkov.

• Language: Slovenian
• Keywords: rak, topoizomeraza IIα, 3, 5-disubstituirani 1, 2, 4-oksadiazoli, katalitični zaviralci
• Work type: Master's thesis/paper
• Organization: FFA - Faculty of Pharmacy
• Year: 2022
• PID: 20.500.12556/RUL-137526
• Publication date in RUL: 21.06.2022

Secondary language

• Language: English
• Title: Synthesis of disubstituted 1,2,4-oxadiazole inhibitors of human DNA topoisomerase IIα

Abstract

Cancer is a group of diseases that have the capability of indefinite cell proliferation. Enzyme human DNA topoisomerase IIα is a well-established target in cancer treatment because it catalyses the induction of topological changes of the DNA molecule and is essential for successful cell division. Small organic compounds can inhibit this enzyme, consequently stopping the cell proliferation of cancer cells. Inhibitors of human DNA topoisomerase IIα are divided into topo II poisons and catalytic inhibitors. Due to serious adverse effects of topo II poisons widely used in chemotherapy, especially cardiotoxicity and induction of secondary malignancies, there is a growing tendency to develop new catalytic inhibitors. In this Master’s thesis, based on the previously known Structure-Activity Relationship of the 3,5-disubstituted 1,2,4-oxadiazoles, a class of catalytic inhibitors that bind to the enzyme’s ATP binding site, we synthesized 11 new derivatives. Additionally, we obtained 6 commercially available derivatives which are structurally similar to our synthesized compounds. All compounds were evaluated using an in vitro topo IIα DNA relaxation assay to determine whether they possess inhibitory activity. None of the synthesized derivatives showed improved topo IIα inhibitory activity compered to compounds which were synthesized in previous research. Among the commercially available derivatives compound 44 displayed promising topo IIα inhibition. This result indicates that additional substitution of the phenyl ring with bonded acetamido group might be beneficial for increased inhibitory activity of the 3,5-disubstituted 1,2,4-oxadiazoles. We also confirmed that compound 44 is a catalytic inhibitor and it can mitigate DNA damage caused by topoisomerase poison etoposide, thus acting via a different mechanism. Molecular docking indicated that a formation of new hydrophobic interactions between the methyl group and residues of the ATP binding site could be plausible reason for the observed better inhibitory activity. Based on the obtained results, we extended the knowledge regarding the SAR of the 3,5-disubstituted 1,2,4-oxadiazoles as topo IIα catalytic inhibitors and gained valuable information for further development of this group of potential anticancer agents towards compounds that would possess comparable efficacy as clinically used topoisomerase II poisons and at the same time display a lower incidence of adverse reactions.

• Keywords: Key words: cancer, topoisomerase IIα, 3, 5-disubstituted 1, 2, 4-oxadiazoles, catalytic inhibitors