2015-06-10 Synthesis of potentially irreversible Akt inhibitors

Van der Westhuizen, Leandi (2014-12)

Thesis

ENGLISH ABSTRACT: Cancer is a leading cause of disease worldwide, with an increasing number of cases reported annually. A member of the phosphatidylinositol 3-kinase-Akt (PI3K-Akt) pathway, Akt, has been found to be dysregulated in certain cancers, aiding in cancer development and progression. There are several known reversible inhibitors of this kinase, but there have been no irreversible inhibitors reported thus far. The aim of this project was therefore to design and synthesise irreversible inhibitors of Akt. Two sets of potential inhibitors were designed, with the first based on the structure of the Type V reversible inhibitor, Akti-1/2. The structure of this inter-domain inhibitor was partly altered, keeping its piperidinyl benzimidazolone functionality intact and replacing the other half of the compound with reported heterocyclic inhibitors of Akt. The second set included the same heterocyclic moieties as the first set, with the piperidinyl benzimidazolone functionality replaced by a 1,2,3-triazole ring-containing structure. Various synthetic routes were explored towards these two sets of compounds, with the key reaction towards the first set being the metal-catalysed synthesis of the required benzimidazolone functionality. Unfortunately, this reaction was found to be exceedingly difficult and no target compounds could be obtained. The key reaction towards the second set of compounds was a click reaction, specifically a copper(I)-catalysed azide alkyne cycloaddition, enabling the convenient synthesis of the 1,4-disubstituted 1,2,3-triazole ring. This route proved more successful, with two target compounds successfully synthesised. These are N-[2-(1-{1-[4-(3-phenylimidazo[1,2-a]pyridin-2-yl)benzyl]piperidin-4-yl}-1H-1,2,3-triazol-4-yl)phenyl]acrylamide and N-[3-(1-{1-[4-(3-phenylimidazo[1,2-a]pyridin-2-yl)benzyl]-piperidin-4-yl}-1H-1,2,3-triazol-4-yl)phenyl]acrylamide. These target compounds were biochemically evaluated for activity against wild-type Akt using iFLiK and HTRF® KinEASE™ assays. Encouragingly, both target compounds had activity against wild-type Akt1, with IC50 values in the nanomolar range. Further evaluation, by LC-MS, revealed the latter compound to be an irreversible inhibitor of wild-type Akt1. This is the first reported irreversible inhibitor of Akt and is proof that Akt can be covalently modified by an appropriate inhibitor. This discovery has allowed for many possibilities for future research towards potent irreversible inhibitors of Akt.

AFRIKAANSE OPSOMMING: Kanker is een van die vernaamste oorsake van siekte ter wêreld, met ‘n groeiende aantal gevalle wat jaarliks aangemeld word. Daar is bevind dat Akt, ‘n lid van die fosfatidielinositol 3-kinase-Akt (PI3K-Akt) roete, gedisreguleer is in sekere vorme van kankers en daardeur kankerontwikkeling en –voortsetting bevorder. Daar is verskeie bekende omkeerbare onderdrukkers van hierdie kinase, maar daar is tot dusver nog geen onomkeerbare onderdrukkers gerapporteer nie. Die doel van hierdie projek was dus om onomkeerbaare onderdrukkers van Akt te ontwerp en te sintetiseer. Twee stelle potensiële onderdrukkers is ontwerp, waarvan die eerste stel gebasseer op die struktuur van die bekende Tipe V omkeerbare onderdrukker, Akti-1/2. Die struktuur van hierdie interdomein onderdrukker is deels verander, met die piperidinielbensimidasoloon funksionaliteit onaangeraak en die ander helfte daarvan vervang deur berigte heterosikliese onderdrukkers van Akt. Die tweede stel verbindings het dieselfde heterosikliese gedeeltes gehad, met die piperidinielbensimidasoloon funksionaliteit vervang deur ‘n 1,2,3-triasoolring-bevattende raamwerk. Verskeie sintetiese roetes is ondersoek ten einde hierdie twee stelle verbinsdings te sintetiseer, met die metaalgekataliseerde sintese van die vereiste bensimidasoloon funksionaliteit as die kernstap in die sintese van die eerste stel verbindings. Ongelukkig is hierdie reaksie as uiters moeilik bevind en geen teikenverbindings kon verkry word nie. Die sleutelreaksie na die tweede stel verbindings was ‘n kliekreaksie, spesifiek ‘n koper(I)gekataliseerde asied-alkyn sikloaddisie, wat die gerieflike sintese van die 1,4-digesubstitueerde 1,2,3-triasool moontlik gemaak het. Hierdie roete was meer suksesvol as die eerste, met twee teikenverbindings suksesvol gesintetiseer. Hierdie verbindings is N-[2-(1-{1-[4-(3-fenielimidaso[1,2-a]piridin-2-iel)bensiel]piperidin-4-iel}-1H-1,2,3-triasol-4-iel)feniel]akrielamied en N-[3-(1-{1-[4-(3-fenielimidaso[1,2-a]piridin-2-iel)bensiel]piperidin-4-iel}-1H-1,2,3-triasol-4-iel)feniel]akrielamied. Deur die gebruik van iFLiK en HTRF® KinEASE™ assessering, is hierdie teikenverbindings biochemies geëvalueer vir aktiwiteit teenoor wilde-tipe Akt1. Beide teikenverbindings het aktiwiteit teenoor wilde-tipe Akt getoon, met IC50 waardes in die nanomolaarruimte. Verdere evaluasie, met behulp van vloeistofchromatografie-massaspektrometrie, het daarop gewys dat die laasgenoemde verbinding ‘n onomkeerbare onderdrukker van wilde-tipe Akt1 is. Dit is die eerste bekende onomkeerbare onderdrukker van Akt en bewys dat Akt wel kovalent gewysig kan word deur ‘n geskikte onderdrukker. Hierdie resultaat maak die deur oop vir verskeie moontlikhede vir toekomstige navorsing met die oog op meer kragtige onderdrukkers van Akt.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/86892
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