The authors report on the synthesis and biological evaluation of new compounds whose structure combines tacrine and indole moieties. Tacrine-indole heterodimers were designed to inhibit cholinesterases and β-amyloid formation, and to cross the blood-brain barrier. The most potent new acetylcholinesterase inhibitors were compounds 3c and 4d (IC50 = 25 and 39 nM, respectively). Compound 3c displayed considerably higher selectivity for acetylcholinesterase relative to human plasma butyrylcholinesterase in comparison to compound 4d (selectivity index: IC50 [butyrylcholinesterase]/IC50 [acetylcholinesterase] = 3 and 0.6, respectively). Furthermore, compound 3c inhibited β-amyloid-dependent amyloid nucleation in the yeast-based prion nucleation assay and displayed no dsDNA destabilizing interactions with DNA. Compounds 3c and 4d displayed a high probability of crossing the blood-brain barrier. The results support the potential of 3c for future development as a dual-acting therapeutic agent in the prevention and/or treatment of Alzheimer's disease.
- MeSH
- Acetylcholinesterase metabolism MeSH
- Alzheimer Disease drug therapy MeSH
- Amyloid beta-Peptides metabolism MeSH
- Cholinesterase Inhibitors chemistry pharmacology MeSH
- Molecular Targeted Therapy MeSH
- Dimerization MeSH
- DNA chemistry MeSH
- Blood-Brain Barrier MeSH
- Indoles chemistry pharmacology MeSH
- Inhibitory Concentration 50 MeSH
- Humans MeSH
- Ligands MeSH
- Neuroprotective Agents chemistry pharmacology MeSH
- Drug Evaluation, Preclinical MeSH
- Molecular Dynamics Simulation MeSH
- Molecular Docking Simulation MeSH
- Tacrine chemistry pharmacology MeSH
- Protein Binding MeSH
- Structure-Activity Relationship MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, N.I.H., Extramural MeSH
BACKGROUND: The design of new heterodimeric dual binding site acetylcholinesterase inhibitors constitutes the main goal-directed to the development of new anticholinesterase agents with the expanded pharmacological profile. Multi-target compounds are usually designed by combining in a hybrid molecule with two or more pharmacophoric moieties that are known to enable interaction with the selected molecular targets. METHODS: All compounds were tested for their inhibitory activity on human AChE/BChE. The Ellman´s method was used to determine inhibition kinetics and IC50 values. In order to predict passive bloodbrain penetration of novel compounds, modification of the parallel artificial membrane permeation assay has been used. Docking studies were performed in order to predict the binding modes of new hybrids with hAChE/ hBChE respectively. RESULTS: In this study, we described the design, synthesis, and evaluation of series tacrine-coumarin and tacrine-quinoline compounds which were found to show potential inhibition of ChEs and penetration of the blood-brain barrier. CONCLUSION: Tacrine-quinoline hybrids 7a exhibited the highest activity towards hBChE (IC50 = 0.97 µmol) and 7d towards hAChE (IC50 = 0.32 µmol). Kinetic and molecular modelling studies revealed that 7d was a mixed-type AChE inhibitor (Ki = 1.69 µmol) and 7a was a mixed-type BChE inhibitor (Ki = 1.09 µmol). Moreover, hybrid 5d and 7c could penetrate the CNS.
- MeSH
- Cholinesterase Inhibitors chemistry pharmacology MeSH
- Blood-Brain Barrier drug effects MeSH
- Kinetics MeSH
- Coumarins chemistry pharmacology MeSH
- Humans MeSH
- Models, Molecular MeSH
- Permeability drug effects MeSH
- Molecular Docking Simulation MeSH
- Tacrine chemistry pharmacology MeSH
- Thiourea chemistry pharmacology MeSH
- Structure-Activity Relationship MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
A novel series of acridine-coumarin hybrids was synthesized and biologically evaluated for their potential inhibitory effect on both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). The newly synthesized derivatives 9a-d have shown higher activity against human AChE (hAChE) compared with 7-MEOTA as the standard drug. Among them derivative 9b exhibited the most potent acetylcholinesterase inhibitory activity, with an IC50 value of 5.85μM compared with 7-MEOTA (IC50=15μM). Molecular modelling studies were performed to predict the binding modes of compounds 9b, 9c and 9f with hAChE/hBuChE.
- MeSH
- Acetylcholinesterase chemistry metabolism MeSH
- Acridines chemical synthesis chemistry metabolism pharmacology MeSH
- Cholinesterase Inhibitors chemical synthesis chemistry metabolism pharmacology MeSH
- Inhibitory Concentration 50 MeSH
- Catalytic Domain MeSH
- Coumarins chemistry MeSH
- Humans MeSH
- Molecular Docking Simulation * MeSH
- Chemistry Techniques, Synthetic MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
Alzheimer's disease is a multifactorial disease that is characterized mainly by Amyloid-β (A-β) deposits, cholinergic deficit and extensive metal (copper, iron)-induced oxidative stress. In this work we present details of the synthesis, antioxidant and copper-chelating properties, DNA protection study, cholinergic activity and amyloid-antiaggregation properties of new multifunctional tacrine-7-hydroxycoumarin hybrids. The mode of interaction between copper(II) and hybrids and interestingly, the reduction of Cu(II) to Cu(I) species (for complexes Cu-5e-g) were confirmed by EPR measurements. EPR spin trapping on the model Fenton reaction, using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trap, demonstrated a significantly suppressed formation of hydroxyl radicals for the Cu-5e complex in comparison with free copper(II). This suggests that compound 5e upon coordination to free copper ion prevents the Cu(II)-catalyzed decomposition of hydrogen peroxide, which in turn may alleviate oxidative stress-induced damage. Protective activity of hybrids 5c and 5e against DNA damage in a Fenton system (copper catalyzed) was found to be in excellent agreement with the EPR spin trapping study. Compound 5g was the most effective in the inhibition of acetylcholinesterase (hAChE, IC50=38nM) and compound 5b was the most potent inhibitor of butyrylcholinesterase (hBuChE, IC50=63nM). Compound 5c was the strongest inhibitor of A-β1-40 aggregation, although a significant inhibition (>50%) was detected for compounds 5b, 5d, 5e and 5g. Collectively, these results suggest that the design and investigation of multifunctional agents containing along with the acetylcholinesterase inhibitory segment also an antioxidant moiety capable of alleviating metal (copper)-induced oxidative stress, may be of importance in the treatment of Alzheimer's disease.
- MeSH
- Acetylcholinesterase chemistry MeSH
- Alzheimer Disease drug therapy metabolism MeSH
- Amyloid beta-Peptides chemistry MeSH
- Butyrylcholinesterase chemistry MeSH
- Cholinesterase Inhibitors * chemical synthesis chemistry MeSH
- GPI-Linked Proteins chemistry MeSH
- Coumarins * chemical synthesis chemistry MeSH
- Humans MeSH
- Copper chemistry MeSH
- Oxidative Stress * MeSH
- Peptide Fragments chemistry MeSH
- Tacrine * chemical synthesis chemistry MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
A new series of substituted tacrine/acridine and tacrine/tacrine dimers with aliphatic or alkylene-thiourea linkers was synthesized and the potential of these compounds as novel human acetylcholinesterase (hAChE) and human butyrylcholinesterase (hBChE) inhibitors with nanomolar inhibition activity was evaluated. The most potent AChE inhibitor was found to be homodimeric tacrine derivative 14a, which demonstrated an IC50 value of 2 nM; this value indicates an activity rate which is 250-times higher than that of tacrine 1 and 7500-times higher than 7-MEOTA 15, the compounds which were used as standards in the study. IC50 values of derivatives 1, 9, 10, 14b and 15 were compared with the dissociation constants of the enzyme-inhibitor complex, Ki1, and the enzyme-substrate-inhibitor complex, Ki2, for. A dual binding site is presumed for the synthesized compounds which possess two tacrines or tacrine and acridine as terminal moieties show evidence of dual site binding. DFT calculations of theoretical desolvation free energies, ΔΔGtheor, and docking studies elucidate these suggestions in more detail.
- MeSH
- Acetylcholinesterase chemistry metabolism MeSH
- Acridines chemistry MeSH
- Enzyme Activation drug effects MeSH
- Butyrylcholinesterase chemistry metabolism MeSH
- Cholinesterase Inhibitors chemistry pharmacology MeSH
- Humans MeSH
- Molecular Conformation MeSH
- Models, Molecular MeSH
- Piperazines chemistry MeSH
- Tacrine chemistry MeSH
- Thiourea chemistry MeSH
- Protein Binding MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
