Inhibition of human cholinesterases by O-alkyloximes

Abstract

Acetilkolinesteraza (AChE) i butirilkolinesteraza (BChE) su enzimi koji kataliziraju hidrolizu acetilkolina i njihova inhibicija jedna je od glavnih strategija u liječenju Alzheimerove bolesti (AB). No, budući da je AB multifaktorijalna bolest, noviji pristup liječenju je razvoj lijekova s višestrukim učinkom koji bi istovremeno djelovali na više mogućih uzročnika bolesti. U sklopu ovog diplomskog rada testirano je 20 O-alkiloksima kao inhibitora ljudskih AChE i BChE, a za nekolicinu spojeva procijenjena je sposobnost vezanja u periferno mjesto AChE i sposobnost inhibicije β-amiloidne samoagregacije. Svi ispitani spojevi reverzibilno su inhibirali obje kolinesteraze u mikromolarnom području, s konstantama inhibicije Ki u rasponu 0,30 – 360 μmol dm–3. Najjačim inhibitorom AChE pokazao se spoj 20 (Ki = 6 μmol dm–3), dok je BChE najjače inhibirao spoj 15 (Ki = 0,30 μmol dm–3). Gotovo svi ispitivani O-alkiloksimi pokazali su se selektivnim inhibitorima BChE u odnosu na AChE. Sposobnost vezanja u periferno mjesto AChE i moguće sprječavanje nastajanja neurotoksičnog kompleksa AChE-β-amiloid pokazali su spojevi 2, 18, 19 i 20. Kao inhibitori β-amiloidne samoagregacije istaknuli su se spojevi 18 i 20. Za sve spojeve je in silico procijenjena sposobnost prolaska kroz krvno-moždanu barijeru te je pokazano da bi mogli prijeći krvno-moždanu barijeru pasivnim transportom.Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are enzymes that catalyze the hydrolysis of acetylcholine, and their inhibition is one of the main strategies in the treatment of Alzheimer's disease (AD). But, AD is a multifactorial disease so a new approach to treatment is development of multi-target directed ligands that would simultaneously act on several possible causes of the disease. As part of this thesis, 20 O-alkyloximes were tested as inhibitors of human AChE and BChE, and some of them were also tested for ability to bind to the peripheral site of AChE and to inhibit β-amyloid self-aggregation. All tested compounds reversibly inhibited both cholinesterases with inhibition constants Ki in the range of 0,30 – 360 μmol dm–3. The most potent AChE inhibitor was compound 20 (Ki = 6 μmol dm–3), while that of BChE was compound 15 (Ki = 0,30 μmol dm–3). Tested O-alkyloximes were generally more selective inhibitors of BChE than of AChE. Compounds 2, 18, 19 and 20 showed the ability to bind to the peripheral site of AChE and possible attenaution of formation of the neurotoxic AChE-β-amyloid complex. Compounds 18 and 20 proved to inhibit β-amyloid self-aggregation. All compounds were evaluated in silico for ability to pass the blood-brain barrier and all of them should be able to pass the blood-brain barrier by passive transport