Synthesis, biological profiling and mechanistic studies of 4-aminoquinoline-based heterodimeric compounds with dual trypanocidal–antiplasmodial activity.

YesDual submicromolar trypanocidal–antiplasmodial compounds have been identified by screening and chemical synthesis of 4-aminoquinoline-based heterodimeric compounds of three different structural classes. In Trypanosoma brucei, inhibition of the enzyme trypanothione reductase seems to be involved in the potent trypanocidal activity of these heterodimers, although it is probably not the main biological target. Regarding antiplasmodial activity, the heterodimers seem to share the mode of action of the antimalarial drug chloroquine, which involves inhibition of the haem detoxification process. Interestingly, all of these heterodimers display good brain permeabilities, thereby being potentially useful for late stage human African trypanosomiasis. Future optimization of these compounds should focus mainly on decreasing cytotoxicity and acetylcholinesterase inhibitory activity

Neuroprotective effects of the multitarget agent AVCRI104P3 in brain of middle-aged mice

Molecular factors involved in neuroprotection are key in the design of novel multitarget drugs in aging and neurodegeneration. AVCRI104P3 is a huprine derivative that exhibits potent inhibitory effects on human AChE, BuChE, and BACE-1 activities, as well as on AChE-induced and self-induced Aβ aggregation. More recently, cognitive protection and anxiolytic-like effects have also been reported in mice treated with this compound. Now, we have assessed the ability of AVCRI104P3 (0.43 mg/kg, 21 days) to modulate the levels of some proteins involved in the anti-apoptotic/apoptotic processes (pAkt1, Bcl2, pGSK3β, p25/p35), inflammation (GFAP and Iba1) and neurogenesis in C57BL/6 mice. The effects of AVCRI104P3 on AChE-R/AChE-S isoforms have been also determined. We have observed that chronic treatment of C57BL/6 male mice with AVCRI104P3 results in neuroprotective effects, increasing significantly the levels of pAkt1 and pGSK3β in the hippocampus and Bcl2 in both hippocampus and cortex, but slightly decreasing synaptophysin levels. Astrogliosis and neurogenic markers GFAP and DCX remained unchanged after AVCRI104P3 treatment, whereas microgliosis was found to be significantly decreased pointing out the involvement of this compound in inflammatory processes. These results suggest that the neuroprotective mechanisms that are behind the cognitive and anxiolytic effects of AVCRI104P3 could be partly related to the potentiation of some anti-apoptotic and anti-inflammatory proteins and support the potential of AVCRI104P3 for the treatment of brain dysfunction associated with aging and/or dementia

Neuroprotective effects of the multitarget agent AVCRI104P3 in brain of middle-aged mice

Funding: Funding for this study was provided by the Ministerio de Ciencia, Innovación y Universidades, the Agencia Estatal de Investigación (AEI) and FEDER (SAF2009-10553, SAF2017-82771-R) and the Generalitat de Catalunya (2014SGR52, 2017SGR106).Molecular factors involved in neuroprotection are key in the design of novel multitarget drugs in aging and neurodegeneration. AVCRI104P3 is a huprine derivative that exhibits potent inhibitory effects on human AChE, BuChE, and BACE-1 activities, as well as on AChE-induced and self-induced Aβ aggregation. More recently, cognitive protection and anxiolytic-like effects have also been reported in mice treated with this compound. Now, we have assessed the ability of AVCRI104P3 (0.43 mg/kg, 21 days) to modulate the levels of some proteins involved in the anti-apoptotic/apoptotic processes (pAkt1, Bcl2, pGSK3β, p25/p35), inflammation (GFAP and Iba1) and neurogenesis in C57BL/6 mice. The effects of AVCRI104P3 on AChE-R/AChE-S isoforms have been also determined. We have observed that chronic treatment of C57BL/6 male mice with AVCRI104P3 results in neuroprotective effects, increasing significantly the levels of pAkt1 and pGSK3β in the hippocampus and Bcl2 in both hippocampus and cortex, but slightly decreasing synaptophysin levels. Astrogliosis and neurogenic markers GFAP and DCX remained unchanged after AVCRI104P3 treatment, whereas microgliosis was found to be significantly decreased pointing out the involvement of this compound in inflammatory processes. These results suggest that the neuroprotective mechanisms that are behind the cognitive and anxiolytic effects of AVCRI104P3 could be partly related to the potentiation of some anti-apoptotic and anti-inflammatory proteins and support the potential of AVCRI104P3 for the treatment of brain dysfunction associated with aging and/or dementia

Novel Donepezil-Based Inhibitors of Acetyl- and Butyrylcholinesterase and Acetylcholinesterase-Induced Beta-Amyloid Aggregation

A novel series of donepezil-tacrine hybrids designed to simultaneously interact with the active, peripheral and midgorge binding sites of acetylcholinesterase (AChE) have been synthesized and tested for their ability to inhibit AChE, butyrylcholinesterase (BChE), and AChE-induced A aggregation. These compounds consist of a unit of tacrine or 6-chlorotacrine, which occupies the same position as tacrine at the AChE active site, and the 5,6-dimethoxy-2-[(4-piperidinyl)methyl]-1-indanone moiety of donepezil (or the indane derivative thereof), whose position along the enzyme gorge and the peripheral site can be modulated by a suitable tether that connects tacrine and donepezil fragments. All of the new compounds are highly potent inhibitors of bovine and human AChE and BChE, exhibiting IC50 values in the subnanomolar or low nanomolar range in most cases. Moreover, six out of the eight hybrids of the series, particularly those bearing an indane moiety, exhibit a significant A antiaggregating activity, which makes them promising anti-Alzheimer drug candidates

SYNTHESIS, PHARMACOLOGICAL EVALUATION, AND MOLECULAR MODELING OF A NOVEL FAMILY OF 6-CHLOROTACRINE-BASED DUAL BINDING SITE ACETYLCHOLINESTERASE INHIBITORS

In the last decade, the design of novel classes of inhibitors of the enzyme acetylcholinesterase (AChE) as therapeutic interventions for Alzheimer\u2019s disease (AD) has been mostly driven by the pivotal finding that AChE can bind the β-amyloid peptide (Aβ), thereby promoting Aβ aggregation as an early event in the neurodegenerative cascade of AD. Blockade of the peripheral site of AChE, the Aβ recognition zone within the enzyme, is expected to affect the AChE-induced Aβ aggregation and could be a potential strategy to modulate the progression of AD. Novel classes of AChE inhibitors (AChEIs) targeting the peripheral site of AChE are emerging as promising disease-modifying anti-Alzheimer drug candidates. Of particular interest are the so-called dual binding site AChEIs, i.e. inhibitors able to simultaneously bind both the active and peripheral sites of AChE, which exhibit significant Aβ antiaggregating effects and high AChE inhibitory potencies. Two isomeric series of dual binding site AChEIs have been designed, synthesized, and tested for their ability to inhibit AChE, butyrylcholinesterase, AChE-induced and self-induced Aβ aggregation and β-secretase (BACE-1). The new hybrids consist of a unit of 6-chlorotacrine and a multicomponent reactionderived pyrano[3,2-c]quinoline scaffold as the active-site and peripheral-site interacting moieties, respectively, connected through an oligomethylene linker containing an amido group at variable position. Molecular modeling studies have confirmed the dual site binding of these hybrids, which retain the potent and selective human AChE inhibitory activity of the parent 6-chlorotacrine, while exhibiting a significant in vitro Aβ anti-aggregating effect and BACE-1 inhibitory activity, thus constituting promising anti-Alzheimerdrug candidates

Huprine-tacrine heterodimers as anti-amyloidogenic compounds of potential interest against Alzheimer's and prion diseases

A family of huprine-tacrine heterodimers has been developed to simultaneously block the active and peripheral sites of acetylcholinesterase (AChE). Their dual site binding for AChE, supported by kinetic and molecular modeling studies, results in a highly potent inhibition of the catalytic activity of human AChE and, more importantly, in the in vitro neutralization of the pathological chaperoning effect of AChE toward the aggregation of both the beta-amyloid peptide (Abeta) and a prion peptide with a key role in the aggregation of the prion protein. Huprine-tacrine heterodimers take on added value in that they display a potent in vitro inhibitory activity toward human butyrylcholinesterase, self-induced Abeta aggregation, and beta-secretase. Finally, they are able to cross the blood-brain barrier, as predicted in an artificial membrane model assay and demonstrated in ex vivo experiments with OF1 mice, reaching their multiple biological targets in the central nervous system. Overall, these compounds are promising lead compounds for the treatment of Alzheimer's and prion diseases

Tacrine-based dual binding site acetylcholinesterase inhibitors as potential disease-modifying anti-Alzheimer drug candidates

Two novel families of dual binding site acetylcholinesterase (AChE) inhibitors have been developed, consisting of a tacrine or 6-chlorotacrine unit as the active site interacting moiety, either the 5,6-dimethoxy-2-[(4-piperidinyl)methyl]-1-indanone fragment of donepezil (or the indane derivative thereof) or a 5-phenylpyrano[3,2-c]quinoline system, reminiscent to the tryciclic core of propidium, as the peripheral site interacting unit, and a linker of suitable length as to allow the simultaneous binding at both sites. These hybrid compounds are all potent and selective inhibitors of human AChE, and more interestingly, are able to interfere in vitro both formation and aggregation of the beta-amyloid peptide, the latter effects endowing these compounds with the potential to modify Alzheimer's disease progression

Functional and autoradiographic characterization of dopamine D2-like receptors in the guinea pig heart.

Dopamine receptors include the D1- (D1 and D5 subtypes) and D2-like (D2, D3, and D4 subtypes) families. D1-like receptors are positively and D2-like receptors negatively coupled to the adenylyl cyclase. Dopamine D2-like (D4 subtype) receptors have been identified in human and rat hearts. However the presence of D2 and D3 receptor subtypes is unclear. Furthermore, their role in cardiac functions is unknown. By autoradiographic studies of guinea pig hearts, we identified D3 and D4 receptors, using the selective radioligands [3H]-7-OH-DPAT and [3H]emonapride (YM-09151-2 plus raclopride). Western blot analysis confirmed D3 and D4 receptors in the right and left ventricle of the same species. Selective agonists of D3 and D4 receptors (+/-)-7-OH-DPAT and PD 168 077 (10(-9) to 10(-5) M, respectively) induced a significant negative chronotropic and inotropic effect in the isolated guinea pig heart preparation. Negative inotropic effect induced by PD 168 077 was associated with an inhibition in cyclase activity. No changes in cyclase activity were found with (+/-)-7-OH-DPAT. The aim of this study is to support the presence of D3 and D4 receptors in the heart. Although our results suggest that D3 and D4 receptors are functionally active in the heart, we need additional information with an antagonist and an agonist of improved potency and selectivity to understand the respective roles of D3 and D4 receptors in the cardiac functions

Pattern recognition by pentraxins

Pentraxins are a family of evolutionarily conserved pattern-recognition proteins that are made up of five identical subunits. Based on the primary structure of the subunit, the pentraxins are divided into two groups: short pentraxins and long pentraxins. C-reactive protein (CRP) and serum amyloid P-component (SAP) are the two short pentraxins. The prototype protein of the long pentraxin group is pentraxin 3 (PTX3). CRP and SAP are produced primarily in the liver while PTX3 is produced in a variery oftissues during inflammation. The main functions of short pentraxins are to recognize a variery of pathogenic agents and then to either eliminate them or neutralize their harmful effects by utilizing the complement pathways and macrophages in the host. CRP binds to modified low-densiry lipoproteins, bacterial polysaccharides, apoptotic cells, and nuclear materials. By virtue of these recognition functions, CRP participates in the resolution ofcardiovascular, infectious, and autoimmune diseases. SAP recognizes carbohydrates, nuclear substances, and amyloid fibrils and thus participates in the resolution of infectious diseases, autoimmuniry, and amyloidosis. PTX3 interacts with several ligands, including growth factors, extracellular matrix component and selected pathogens, playing a role in complement activation and facilitating pathogen recognition by phagoeytes. In addition, data in gene-targeted mice show that PTX3 is essential in female fertiliry, participating in the assembly of the cumulus oophorus extracellular matrix. PTX3 is therefore a nonredundant component ofthe humoral arm of innate immuniry as well as a tuner of inflammation. Thus, in conjunction with the other components ofinnate immuniry, the pentraxins use their pattern-recognition properry for the benefit of the host