Synthesis and evaluation of N-methylvinylpyridine and epoxybenzene covalent fragments

Tarčni kovalentni inhibitorji so spojine, ki z nekatalitičnim aminokislinskim ostankom v tarčnem encimu tvorijo kovalentno vez in na ta način zavrejo njegovo aktivnost. Kovalenten zaviralec dobimo s pripenjanjem elektrofilne funkcionalne skupine na nekovalenten zaviralec oziroma fragment. Čeprav imajo tarčni kovalentni inhibitorji kar nekaj prednosti, pa je njihova uporaba pri načrtovanju novih zdravilnih učinkovin še vedno omejena zaradi morebitnega pojava neželenih stranskih učinkov, ki so lahko posledica reakcije elektrofilne funkcionalne skupine v zaviralcu z netarčnimi nukleofili v organizmu. Monoamin oksidaza (MAO) je flavoencim vezan na zunanjo mitohondrijsko membrano. Poznamo dve obliki MAO: MAO-A in MAO-B, ki imata v 73 % podobno aminokislinsko zaporedje. Za zdravljenje depresije so se sprva uporabljali ireverzibilni neselektivni MAO zaviralci, zaradi neželenih stranskih učinkov pa je razvoj šel v smeri selektivnih zaviralcev. Selektivni reverzibilni zaviralci MAO-A se prav tako uporabljajo za zdravljenje depresije, medtem ko se selektivni reverzibilni zaviralci MAO-B uporabljajo pri terapiji Parkinsonove bolezni. Rezistenca bakterij na mnoge protibakterijske učinkovine predstavlja veliko grožnjo javnemu zdravju, zato je razvoj učinkovitih selektivnih protibakterijskih učinkovin izredno pomemben. Encim MurA predstavlja dobro tarčo, saj sodeluje v začetnih stopnjah biosinteze peptidoglikana. S kvarternizacijo dušikovega atoma na piridinu lahko dosežemo večjo hitrost in kemoselektivnost vezave spojine na cisteinske ostanke tarčnih proteinov, zato smo sintetizirali vinilpiridine ter iz njih še N-metilvinilpiridine. Zaviralne lastnosti smo preverili na encimih hMAO-A, hMAO-B, MurA in imunoproteasomski podenoti β5i. Spojini 6 in 7, ki sta metilirana analoga spojin 2 in 3, sta močnejša zaviralca hMAO-A kot nemetilirana analoga. Epoksid A je selektivno zaviral hMAO-A, zato smo ga resintetizirali (spojina 25), sintetizirali pa smo še deset fragmentov, ki imajo na fenilnem obroču različne elektron akceptorske substituente ter tako preverili odnos med strukturo in delovanjem teh spojin. Encim hMAO-A selektivno zavirajo spojine s sferično obliko, encim hMAO-B pa linearne hidrofobne spojine.Targeted covalent inhibitors are compounds that form a covalent bond with a non-catalytic amino acid residue in targeted enzyme and thus inhibit its activity. Covalent inhibitors can be designed via attachement of an electrophilic functional group to a non-covalent inhibitor or fragment. Although the usage of targeted covalent inhibitors has several advantages, their application in drug design is still limited due to the possible occurence of side effects resulting from the reaction of electrophilic functional group with non-target nucleophiles in the body. Monoamine oxidase (MAO) is a flavoenzyme bound to outer mitochondrial membrane. There are two isoforms of MAO: MAO-A and MAO-B, which share 73 % amino acid sequence identity. At first, irreversible non-selective MAO inhibitors were used to treat depression, and selective inhibitors were later designed to mitigate the side effects. Selective reversible MAO-A inhibitors are used to treat depression, while selective reversible MAO-B inhibitors are used in the management of Parkinson\u27s disease. Bacterial resistance is a major threat to public health. Therefore, the development of effective and selective antibacterial agents is of essence. MurA enzyme is a good target for new drugs as it participates in early stages of peptidoglycan biosynthesis. Quaternization of the nitrogen atom on pyridine can result in higher binding rates and chemoselectivity of binding to the cysteine residues of targeted proteines. Thus, vinylpyridines and N-methylvinylpyridines were synthesized. The inhibitory potencies were determined on hMAO-A, hMAO-B, MurA and β5i imunoproteasome subunit. Compounds 6 and 7, the methylated analogues of 2 and 3, are more potent hMAO-A inhibitors than non-methylated derivatives. Epoxide A selectively inhibited hMAO-A, therefore we resynthesized it (25) and prepared ten additional fragments with different electron acceptor substituents on the phenyl ring. Compounds were tested and the structure activity relationships were analyzed. Compounds with spherical shape are hMAO-A selective, while linear and hydrophobic compounds are hMAO-B selective inhibitors