ITH4012 (Ethyl 5-Amino-6,7,8,9-tetrahydro-2-methyl-4-phenylbenzol[1,8]naphthyridine-3-carboxylate), a Novel Acetylcholinesterase Inhibitor with “Calcium Promotor” and Neuroprotective Properties

Abstract

7,8,8] naphthyridine-3-carboxylate (ITH4012) is a novel tacrine derivative that can reduce cell death induced by various compounds with different mechanisms of action, such as thapsigargin (reticular stress), H 2 O 2 (free radicals), and veratridine (calcium overload), in bovine chromaffin cell. Cell viability, quantified as lactic dehydrogenase release, was significantly reduced by ITH4012 at concentrations ranging from 0.01 to 3 M. In the human neuroblastoma cell line SH-SY5Y, ITH4012 also reduced amyloid ␤ 25-35 -induced apoptosis, determined by flow cytometry. ITH4012 caused a slight elevation in the cytosolic concentration of Ca 2ϩ in fura 2-loaded bovine chromaffin cells, which could be related to the induction of protein synthesis relevant for cell survival. Blockade of protein synthesis by cycloheximide or blockade of Bcl-2's active site with HA14-1 (ethyl 2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate) reversed the cytoprotective action of ITH4012. Furthermore, exposure of bovine chromaffin cells for 24 or 48 h to neuroprotective concentrations of this compound enhanced, nearly 3-fold, the expression of the antiapoptotic protein Bcl-2. In conclusion, ITH4012 is a tacrine derivative that maintains acetylcholinesterase-inhibiting activity (IC 50 ϭ 0.8 M) but has the additional property of acting as a calcium promotor, a property leading to neuroprotection through the induction of antiapoptotic proteins.Alzheimer's disease (AD) is a degenerative disorder of the central nervous system found primarily among the aged. It is the most common type of dementia in western societies and has been creating profound economic and social impacts as the elderly population continues to increase (Guttman et al., 1999). The hallmarks of the illness are extracellular deposition of neuritic plaques of amyloid-␤ peptide (A␤), intracellular formation of neurofibrillary tangles, and selective neuronal loss. Of all biochemical changes observed in AD patients, only the reduction in number of functional neuronal nicotinic receptors is related to neuropsychiatric symptoms (Schroder et al., 1991). For this reason, the only pharmacotherapeutical strategy that, until now, has proven to have some efficacy in slowing progression of the illness is that which improves cholinergic neurotransmission, counteracting the deficit of cerebral acetylcholine (Standaert and Young, 1996). Therefore, acetylcholinesterase inhibition is currently the therapeutic strategy most commonly used to treat Alzheimer's patients.On the other hand, moderate chronic depolarization has demonstrated an ability to increase the survival of different neuronal types. Also, there is evidence that this effect is mediated by the mild and sustained elevation of [Ca 2ϩ ] c ,

AChE deficiency or inhibition decreases apoptosis and p53 expression and protects renal function after ischemia/reperfusion

“…Explanations of the neuroprotective effect observed in these studies included activation of the central cholinergic system [10,12], down-regulation of pro-apoptotic p53 and Bax, stimulation of anti-apoptotic Bcl-2 [5,6,9], or blockage of NMDA receptors [11]. However, no consideration of the role of AChE-S was proposed.…”

“…Although the neuroprotective effects of several AChE inhibitors against apoptosis have been reported in vitro, these studies were limited to cell lines or primary cultured cells from the central or peripheral nervous system [5][6][7][8][9][10][11][12]. Explanations of the neuroprotective effect observed in these studies included activation of the central cholinergic system [10,12], down-regulation of pro-apoptotic p53 and Bax, stimulation of anti-apoptotic Bcl-2 [5,6,9], or blockage of NMDA receptors [11].…”

“…Acetylcholinesterase inhibitors (AChEIs) may block the degradation of acetylcholine, thus increasing the efficacy of the remaining cholinergic neurons. However, most AChEIs also have the ability to protect cells against cell death induced by various apoptotic stimuli with different mechanisms of action [5][6][7][8][9][10][11]. All of these studies were based on cell lines derived from the central or peripheral nervous system, and the antiapoptotic mechanisms involved down-regulation of proapoptotic p53 and bax, the stimulation of anti-apoptotic bcl-2 [5,6],or the direct blocking of NMDA receptors [11].…”

Multifunctional neuroprotective drugs targeting monoamine oxidase inhibition, iron chelation, adenosine receptors, and cholinergic and glutamatergic action for neurodegenerative diseases

“…Orozco et al [39] investigated ITH4012 against a variety of toxic stimuli that may be relevant to the pathophysiology of AD. Their studies indicated that ITH4012 reduced cell death that was induced by thapsigargin (causing reticular stress), H 2 O 2 (through the Propargyl MAO inhibitory moiety free radical mechanism) and veratridine (resulting in Ca 2+ overload) at concentrations in the range of 0.01 -3 µM.…”

Novel Multifunctional Anti-Alzheimer Drugs with Various CNS Neurotransmitter Targets and Neuroprotective Moieties

“…This compound has been shown in an early study to have AChE inhibitory activity (IC 50 = 0.8 μM) [92]. ITH-4012 was investigated against a variety of toxic stimuli that may be relevant to the pathophysiology of AD [93]. These studies [101,102] indicated that ITH-4012 reduced cell death induced by thapsigargin (causing reticular stress), H 2 O 2 (through the free radical mechanism) and veratridine (resulting in calcium overload), at concentrations ranging from 0.01 μM to 3 μM.…”