Naslov
Design and evaluation of phenyltetrahydroisoquinoline pyridinium aldoximes as reactivators of nerve-agent-inhibited human cholinesterases

Autori
Maček Hrvat, Nikolina ; Kalisiak, Jaroslaw ; Šinko, Goran ; Zandona, Antonio ; Radić, Zoran ; Sharpless, K. Barry ; Taylor, Palmer ; Kovarik, Zrinka

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Abstract book of the 17th Medical Chemical Defense Conference "Chemical Warfare Agents - old problems and new challenges" / - München, 2019, 138-138

Skup
17th Medical Chemical Defense Conference "Chemical Warfare Agents - old problems and new challenges"

Mjesto i datum
München, Njemačka, 27.03.2019. - 28.03.2019

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
oximes, buryrylcholinesterase, acetylcholinesterase

Sažetak
We designed bifunctional aldoximes that comprise a peripheral site ligand connected to a reactivator function by a covalent linker with the aim of improving the binding affinity by anchoring phenyltetrahydroisoquinoline moiety at the acetylcholinesterase (AChE) peripheral site, and at the same time preventing unproductive binding to the active site. Oximes were synthesized by Huisgen 1, 3 dipolar cycloaddition between pyridinium based azide- and alkyne-building blocks containing phenyltetrahydroisoquinoline (PIQ) moiety and then tested as potential reactivators of cyclosarin-, sarin-, VX- and tabun-inhibited AChE and butyrylcholinesterase (BChE). The reactivators exhibited higher potency than 2-PAM or HI-6 in restoring BChE activity but none was efficient for AChE although the dissociation inhibition constants of AChE were in nM range classifying the tested oximes as its high-affinity ligands. Non-competitive inhibition of AChE and slow reactivation rates indicated that aldoximes were stabilized in the peripheral site in an unproductive form. Although docking proved our hypothesis of the stabilization of PIQ moiety within the peripheral site and the oxime group directed towards the catalytic site of AChE, it seems that the length of the linker had to be optimized so the oxime moiety could approach the enzyme’s phosphylated serine without unbinding from the peripheral site. Due to a lack of peripheral aromatic residues in BChE, aldoximes inhibited BChE less potently than AChE (in sub-nano to micro-molar range). Detailed kinetics of the reactivation of cyclosarin and sarin-inhibited BChE with selected aldoximes showed that the affinity for the phosphylated BChE conjugate in terms of 1/KOX decreased up to 400 times. In addition, the absence of the universality of reactivation restored BChE inhibited with cyclosarin, sarin, but not that inhibited with VX and tabun underlining the comprehensiveness of the reactivation mechanism and the importance of phosphorus moiety conjugated at the catalytic serine. In conclusion, our study demonstrated that high-affinity aldoximes based on the peripheral site ligand did not improve their reactivation capability implying that the stabilization of the oxime group in the vicinity of the phosphorus conjugated at the catalytic serine providing a convenient position for the nucleophilic attack is the major criteria for efficient reactivation. This work was supported by the National Institutes of Health (U01 NS058046U01 and U01 NS 5058048) and by the Croatian Science Foundation (HrZZ-IP-2018-01-7683).

Izvorni jezik
Engleski

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