Dihydroquinoline Carbamate DQS1-02 as a Prodrug of a Potent Acetylcholinesterase Inhibitor for Alzheimer’s Disease Therapy: Multigram-Scale Synthesis, Mechanism Investigations, in Vitro Safety Pharmacology, and Preliminary in Vivo Toxicology Profile

Abstract

We previously characterized a set of potent pseudo-irreversible inhibitors of acetylcholinesterase (AChE) based on a redox prodrug strategy. Among the various synthesized prodrugs, compound 1, namely DQS1-02, displayed favorable physicochemical properties and was chosen to achieve the necessary prerequisite investigations prior to preclinical evaluation. Herein, we first report a practical multigram-scale nine-step synthesis of prodrug 1 with a good overall yield (18%) as well as a full investigation on the inhibition mechanism of AChE by the parent drug 2 by means of UV−vis spectroscopy, NMR, and tandem mass spectrometry. In the second part, we describe the ADME properties of DQS1-02, the safety pharmacology of both compounds 1 and 2, and the preliminary results of an in vivo toxicology study in rats. Last but not the least, we also demonstrated that AChE inhibitor 2 was highly selective for AChE, whereas the corresponding prodrug 1 proved to be remarkably safe, making it a valuable preclinical candidate.

Pleiotropic prodrugs: Design of a dual butyrylcholinesterase inhibitor and 5-HT6 receptor antagonist with therapeutic interest in Alzheimer’s disease

“…The stability of the carbamate 18 in buffer or in presence of BuChE and its possible in vitro decarbamoylation were tested. We used in this aim a new analytical method described by Alix et al [39] and developed for compound 5 [31]. Owing to its high homology with the active-site sequence of the human BuChE and its commercial availability, butyrylcholinesterase form equine source eqBuChE is commonly used for in vitro assays and was chosen for this study.…”

Inhibiting Acetylcholinesterase to Activate Pleiotropic Prodrugs with Therapeutic Interest in Alzheimer’s Disease

“…The in vitro decarbamoylation of 20 in the presence of AChE was established according to a new analytical method developed by Alix et al [19]. A large excess of Electrophorus electricus ( eel )AChE was added to a solution of 20 in a phosphate-buffered saline (PBS) buffer (pH 7.4) at 25 °C.…”

Design, Synthesis, and In Vitro Biological Activities of a Bio-Oxidizable Prodrug to Deliver Both ChEs and DYRK1A Inhibitors for AD Therapy

“…As a complement to the preceding studies, the ability of compounds 14 and 4 to cross the blood brain barrier (BBB) by passive diffusion was determined by PAMPA BBB assays. Unsurprisingly [39,40,41,42], the obtained values showed that the quinolinium salt 14 is not able to cross the BBB by this transport process (Pe = 0.00 × 10 −6 cm·s −1 ), whereas the dihydroquinoline compound 4 , which is more lipophilic, diffuses moderately (Pe = 2.41 × 10 −6 cm·s −1 ).…”

“…Other reports also suggest a role of the DYRK1A activity in the amyloid beta peptide (Aβ) accumulation [34,35]. For many years, our group has been interested in the development of new ChEIs, with the aim of replacing the marketed AChEIs by more specific and less toxic ones [36,37,38,39,40,41,42]. In this context, we previously patented and reported on the design of brain-penetrant bio-oxidative prodrugs of potent pseudo-irreversible AChE carbamate-based inhibitors (Scheme 1A) [41].…”