Santiago Conde

Novel Tacrine−8-Hydroxyquinoline Hybrids as Multifunctional Agents for the Treatment of Alzheimer’s Disease, with Neuroprotective, Cholinergic, Antioxidant, and Copper-Complexing Properties

Tacrine and PBT2 (an 8-hydroxyquinoline derivative) are well-known drugs that inhibit cholinesterases and decrease beta-amyloid (Abeta) levels by complexation of redox-active metals, respectively. In this work, novel tacrine-8-hydroxyquinoline hybrids have been designed, synthesized, and evaluated as potential multifunctional drugs for the treatment of Alzheimers disease. At nano- and subnanomolar concentrations they inhibit human acetyl- and butyrylcholinesterase (AChE and BuChE), being more potent than tacrine. They also displace propidium iodide from the peripheral anionic site of AChE and thus could be able to inhibit Abeta aggregation promoted by AChE. They show better antioxidant properties than Trolox, the aromatic portion of vitamin E responsible for radical capture, and display neuroprotective properties against mitochondrial free radicals. In addition, they selectively complex Cu(II), show low cell toxicity, and could be able to penetrate the CNS, according to an in vitro blood-brain barrier model.

Neuroprotective and Cholinergic Properties of Multifunctional Glutamic Acid Derivatives for the Treatment of Alzheimer’s Disease

Novel multifunctional compounds have been designed, synthesized, and evaluated as potential drugs for the treatment of Alzheimers disease (AD). With an L-glutamic moiety as a suitable biocompatible linker, three pharmacophoric groups were joined: (1) an N-benzylpiperidine fragment selected to inhibit acetylcholinesterase by interacting with the catalytic active site (CAS), (2) an N-protecting group of the amino acid, capable of interacting with the acetylcholinesterase (AChE)-peripheral anionic site (PAS) and protecting neurons against oxidative stress, and (3) a lipophilic alkyl ester that would facilitate penetration into the central nervous system by crossing the blood-brain barrier. At submicromolar concentration, they inhibit AChE and butyrylcholinesterase (BuChE) of human origin, displace the binding of propidium iodide from the PAS of AChE, and could thus inhibit Abeta aggregation promoted by AChE. They also display neuroprotective properties against mitochondrial free radicals, show low toxicity, and could be able to penetrate into the CNS.

N-Benzylpiperidine derivatives of 1,2,4-thiadiazolidinone as new acetylcholinesterase inhibitors

A new family of 1,2,4-thiadiazolidinone derivatives containing the N-benzylpiperidine fragment has been synthesised. The acetylcholinesterase (AChE) inhibitory activity of all compounds was measured using Ellmans method and some of them turned out to be as potent as tacrine. Furthermore, compound 13 was as active as tacrine in reversing the blockade induced by tubocurarine at rat neuromuscular junction. Additionally, receptor binding studies provided new lead compounds for further development of alpha2-adrenergic and sigma-receptor antagonists. Molecular dynamic simulation using X-ray crystal structure of AChE from Torpedo californica was used to explain the possible binding mode of these new compounds.

New Melatonin–N,N-Dibenzyl(N-methyl)amine Hybrids: Potent Neurogenic Agents with Antioxidant, Cholinergic, and Neuroprotective Properties as Innovative Drugs for Alzheimer’s Disease

Here, we describe a new family of melatonin-N,N-dibenzyl(N-methyl)amine hybrids that show a balanced multifunctional profile covering neurogenic, antioxidant, cholinergic, and neuroprotective properties at low-micromolar concentrations. They promote maturation of neural stem cells into a neuronal phenotype and thus they could contribute to CNS repair. They also protect neural cells against mitochondrial oxidative stress, show antioxidant properties, and inhibit human acetylcholinesterase (AChE). Moreover, they displace propidium from the peripheral anionic site of AChE, preventing the β-amyloid aggregation promoted by AChE. In addition, they show low cell toxicity and can penetrate into the CNS. This multifunctional profile highlights these melatonin-N,N-dibenzyl(N-methyl)amine hybrids as useful prototypes in the research of innovative drugs for Alzheimers disease.

Switching Reversibility to Irreversibility in Glycogen Synthase Kinase 3 Inhibitors: Clues for Specific Design of New Compounds

Development of kinase-targeted therapies for central nervous system (CNS) diseases is a great challenge. Glycogen synthase kinase 3 (GSK-3) offers a great potential for severe CNS unmet diseases, being one of the inhibitors on clinical trials for different tauopathies. Following our hypothesis based on the enhanced reactivity of residue Cys199 in the binding site of GSK-3, we examine here the suitability of phenylhalomethylketones as irreversible inhibitors. Our data confirm that the halomethylketone unit is essential for the inhibitory activity. Moreover, addition of the halomethylketone moiety to reversible inhibitors turned them into irreversible inhibitors with IC(50) values in the nanomolar range. Overall, the results point out that these compounds might be useful pharmacological tools to explore physiological and pathological processes related to signaling pathways regulated by GSK-3 opening new avenues for the discovery of novel GSK-3 inhibitors.

N-Acylaminophenothiazines: neuroprotective agents displaying multifunctional activities for a potential treatment of Alzheimer’s disease

We have previously reported the multifunctional profile of N-(3-chloro-10H-phenothiazin-10-yl)-3-(dimethylamino)propanamide (1) as an effective neuroprotectant and selective butyrylcholinesterase inhibitor. In this paper, we have developed a series of N-acylaminophenothiazines obtained from our compound library or newly synthesised. At micro- and sub-micromolar concentrations, these compounds selectively inhibited butyrylcholinesterase (BuChE), protected neurons against damage caused by both exogenous and mitochondrial free radicals, showed low toxicity, and could penetrate into the CNS. In addition, N-(3-chloro-10H-phenothiazin-10-yl)-2-(pyrrolidin-1-yl)acetamide (11) modulated the cytosolic calcium concentration and protected human neuroblastoma cells against several toxics, such as calcium overload induced by an L-type Ca2+-channel agonist, tau-hyperphosphorylation induced by okadaic acid and Aβ peptide.

Glycogen Synthase Kinase‑3 Inhibitors as Potent Therapeutic Agents for the Treatment of Parkinson Disease.

Parkinsons disease (PD) is a devastating neurodegenerative disorder characterized by degeneration of the nigrostriatal dopaminergic pathway. Because the current therapies only lead to temporary, limited improvement and have severe side effects, new approaches to treat PD need to be developed. To discover new targets for potential therapeutic intervention, a chemical genetic approach involving the use of small molecules as pharmacological tools has been implemented. First, a screening of an in-house chemical library on a well-established cellular model of PD was done followed by a detailed pharmacological analysis of the hits. Here, we report the results found for the small heterocyclic derivative called SC001, which after different enzymatic assays was revealed to be a new glycogen synthase kinase-3 (GSK-3) inhibitor with IC(50) = 3.38 ± 0.08 μM. To confirm that GSK-3 could be a good target for PD, the evaluation of a set of structurally diverse GSK-3 inhibitors as neuroprotective agents for PD was performed. Results show that inhibitors of GSK-3 have neuroprotective effects in vitro representing a new pharmacological option for the disease-modifying treatment of PD. Furthermore, we show that SC001 is able to cross the blood-brain barrier, protects dopaminergic neurons, and reduces microglia activation in in vivo models of Parkinson disease, being a good candidate for further drug development.

Thienylhalomethylketones: Irreversible glycogen synthase kinase 3 inhibitors as useful pharmacological tools.

Thienylhalomethylketones, whose chemical, biological, and pharmaceutical data are here reported, are the first irreversible inhibitors of GSK-3beta described to date. Their inhibitory activity is likely related to the cysteine residue present in the ATP-binding site, which is proposed as a relevant residue for modulation of GSK-3 activity. The good cell permeability of the compounds allows them to be used in different cell models. Overall, the results presented here support the potential use of halomethylketones as pharmacological tools for the study of GSK-3beta functions and suggest a new mechanism for GSK-3beta inhibition that may be considered for further drug design.

Non-Cholinergic Pharmacotherapy Approaches to the Future Treatment of Alzheimers Disease

Research on the molecular basis of Alzheimers disease has elucidated pathogenic pathways from which a range of rational pharmacological interventions has emerged. The most promising strategies involve approaches to retarding, halting or preventing the formation or accumulation of beta amyloid plaques and neurofibrillary tangles. Other therapeutic approaches include those acting via excitatory amino acid receptors, limiting the oxidative stress and inflammatory response associated with dementia, molecules with nerve growth factor like activity. In the present article these and the other recent advances in the neurobiology and pharmacotherapy of AD will be reviewed.

Regio- and enantioselectivity of the Candida antarctica lipase catalyzed amidations of Cbz-l- and Cbz-d-glutamic acid diesters

Abstract Candida antarctica lipase (CAL) catalyzed amidation of Cbz-glutamic acid diesters takes place in a regioselective way to give the corresponding monoamide derivatives. The regioselectivity was found to be dependent on the reacting Glu enantiomer. Thus, amidations of Cbz- l -Glu diesters regiospecifically afforded α-amide while the γ-ester is selectively substituted in the d -enantiomer. This enzymatic reaction also shows enantioselectivity when a chiral amine is used as nucleophile.