A library of 31 butyrylcholinesterase (BChE) and cathepsin B (CatB) inhibitors, was screened in vitro for inhibition of deoxyribonuclease I (DNase I). Compounds 22, 8 and 7 are among the most potent synthetic non-peptide DNase I inhibitors reported up to date. Three 8-hydroxyquinoline analogues inhibited both DNase I and BChE with IC50 values below 35 microM and 50 nM, respectively, while 2 nitroxoline derivatives inhibited DNase I and Cat B endopeptidase activity with IC50 values below 60 microM and 20 microM, respectively. Selected derivatives were screened for various co-target binding affinities at dopamine D2 and D3, histamine H3 and H4 receptors and inhibition of 5-lipoxygenase. Compound 8 bound to the H3 receptor and is highlighted as the most promising multifunctional ligand with a favorable pharmacokinetic profile and one of the most potent non-peptide DNase I inhibitors. The present study demonstrates that 8-hydroxyquinoline is a structural fragment critical for DNase I inhibition in the presented series of compounds.
The limited clinical efficacy of current symptomatic treatment and minute effect on progression of Alzheimer's disease has shifted the research focus from single targets towards multi-target-directed ligands. Here, a potent selective inhibitor of human butyrylcholinesterase was used as the starting point to develop a new series of multifunctional ligands. A focused library of derivatives was designed and synthesised that showed both butyrylcholinesterase inhibition and good antioxidant activity as determined by the DPPH assay. The crystal structure of compound 11 in complex with butyrylcholinesterase revealed the molecular basis for its low nanomolar inhibition of butyrylcholinesterase (Ki=1.09+/-0.12nM). In addition, compounds 8 and 11 show metal-chelating properties, and reduce the redox activity of chelated Cu(2+) ions in a Cu-ascorbate redox system. Compounds 8 and 11 decrease intracellular levels of reactive oxygen species, and are not substrates of the active efflux transport system, as determined in Caco2 cells. Compound 11 also protects neuroblastoma SH-SY5Y cells from toxic Abeta1-42 species. These data indicate that compounds 8 and 11 are promising multifunctional lead ligands for treatment of Alzheimer's disease.
Tremendous efforts have been dedicated to the development of effective therapeutics against Alzheimer's disease, which represents the most common debilitating neurodegenerative disease. Multifunctional agents are molecules designed to have simultaneous effects on different pathological processes. Such compounds represent an emerging strategy for the development of effective treatments against Alzheimer's disease. Here, we report on the synthesis and biological evaluation of a series of nitroxoline-based analogs that were designed by merging the scaffold of 8-hydroxyquinoline with that of a known selective butyrylcholinesterase inhibitor that has promising anti-Alzheimer properties. Most strikingly, compound 8g inhibits self-induced aggregation of the amyloid beta peptide (Abeta1-42), inhibits with sub-micromolar potency butyrylcholinesterase (IC50=215 nM), and also selectively complexes Cu(2+). Our study thus designates this compound as a promising multifunctional agent for therapeutic treatment of Alzheimer's disease. The crystal structure of human butyrylcholinesterase in complex with compound 8g is also solved, which suggests ways to further optimize compounds featuring the 8-hydroxyquinoline scaffold.
Title: Phosphonate inhibitors of antigen 85C, a crucial enzyme involved in the biosynthesis of the Mycobacterium tuberculosis cell wall Gobec S, Plantan I, Mravljak J, Wilson RA, Besra GS, Kikelj D Ref: Bioorganic & Medicinal Chemistry Lett, 14:3559, 2004 : PubMed
The first phosphonate inhibitors of antigen 85C--a major protein component of the Mycobacterium tuberculosis cell wall possessing mycolyltransferase activity were prepared using structure-based design. These potential novel antituberculosis agents, consisting of a phosphonate moiety, hydrophobic alkyl chain and a simple trehalose-mimicking aromatic structure, were designed as tetrahedral transition-state analogue inhibitors of antigen 85C, which catalyzes the key mycolyltransferase reaction involved in cell wall biosynthesis.
