WO2019068771A1

WO2019068771A1 - Use of sigma receptor ligands in age-related cognitive impairments

Info

Publication number: WO2019068771A1
Application number: PCT/EP2018/076921
Authority: WO
Inventors: Manuel Merlos Roca; Daniel Zamanillo Castanedo
Original assignee: Esteve Pharmaceuticals, S.A.
Priority date: 2017-10-04
Filing date: 2018-10-03
Publication date: 2019-04-11

Abstract

The invention relates to sigma-1 receptor inhibitors and, in particular, to compounds of general formula (I), (I) having pharmacological activity towards the sigma receptor, for use in the treatment of age related cognitive impairments.

Description

USE OF SIGMA RECEPTOR LIGANDS IN AGE-RELATED COGNITIVE IMPAIRMENTS

FIELD OF THE INVENTION

The present invention relates to the use of sigma receptor inhibitors and more particularly to some pyrazole derivatives, and to the use of pharmaceutical compositions comprising them for the treatment of age-related cognitive impairments.

BACKGROUND OF THE INVENTION

With an increasingly aged population, cognitive impairment or normal (non-pathological) cognitive aging is a major health and social issue worldwide. Cognitive decline is among the most feared aspects of growing old. It is also the most costly, in terms of the financial, personal and societal burdens.

Although there is little age-associated decline in some mental functions, such as verbal ability, some numerical abilities and general knowledge, other mental capabilities decline from middle age onwards, or even earlier. The latter include aspects of memory, attention, processing speed, visuospatial performance, executive functioning, and reasoning. Slowed speed of information processing appears to account for a substantial proportion of age- associated decline in all affected cognitive domains. These aging-related deficits are important for carrying out everyday activities, living independently and leading a fulfilling life and present challenges to our aging society.

Within the range defined by "normal cognitive aging" i.e. in people who would not meet the criteria for dementia or any of the varieties of mild cognitive impairment, people differ greatly in the degree to which their brains decline with age. Some memory issues are due to stress, anxiety, or depression. There are contributions to understanding individual differences in normal cognitive ageing from genetics, general health and medical disorders such as atherosclerotic disease, biological processes such as inflammation, neurobiological changes, diet and lifestyle. It is known that normal aging is accompanied by increased neuroinflammation and synaptic dysfunction, nevertheless the onset and progression of these deficits throughout the life span remain unknown. Normal cognitive aging is associated with a decline in various memory abilities in many cognitive tasks. The phenomenon is known as age-related memory impairment (AMI) or age-associated memory impairment (AAMI). Age-related memory impairment is characterized by self-perception of memory loss. About 40% of people aged 65 or older have age associated memory impairment. About 1 % of them will progress to dementia (G. Small. BMJ (2002) 324, 1502).

Existing evidence from observational studies suggests that dietary factors including antioxidants, fatty acids, folate, and B vitamins are associated with lower incidence of cognitive decline, stroke, and dementia. However, despite a wealth of data from prospective studies, few interventions have reported positive effects of nutritional supplementation on cognitive outcomes.

Consequently, it is an object of the present invention to provide novel medicaments, which are suitable for the treatment of age-related cognitive impairment.

The sigma (σ) receptor is a cell surface and endoplasmic reticulum receptor expressed in the central nervous system (CNS) among other tissues. From studies of the biology and function of sigma receptors, evidence has been presented that sigma receptor ligands may be useful in the treatment of psychosis and movement disorders such as dystonia and tardive dyskinesia, and motor disturbances associated with Huntington's chorea or Tourette's syndrome and in Parkinson's disease (Walker, J.M. et al, Pharmacological Reviews, 1990, 42, 355). It has been reported that the known sigma receptor ligand rimcazole clinically shows effects in the treatment of psychosis (Hanner, M. et al. Proc. Natl. Acad. Sci., 1996, 93:8072-8077). The sigma binding sites have preferential affinity for the dextrorotatory isomers of (+)SKF 10047, (+)cyclazocine, and (+)pentazocine and also for some narcoleptics such as haloperidol.

The sigma receptor has at least two subtypes, which may be discriminated by stereoselective isomers of these pharmacoactive drugs. SKF 10047 has nanomolar affinity for the sigma 1 (σ-1 ) site, and has micromolar affinity for the sigma (σ-2) site. Haloperidol has similar affinities for both subtypes. Endogenous sigma ligands are not known, although progesterone has been suggested to be one of them. The existence of sigma receptors in the central nervous system (CNS), immune and endocrine systems have suggested a likelihood that it may serve as link between the three systems. Activation of σ-1 receptor (σ-I R) is thought to play a crucial role in learning and memory thought modulating neurotransmission and N-methyl-D-aspartate (NMDA)-type of glutamatergic system (Maurice et al, 2001 . Brain Res. Rev. 37, 1 16-132). Indeed, agonists for σ-I R are effective in attenuating the learning deficits in aged and senescence- accelerated mice (Monnet and Maurice, 2006. J Pharmacol. Sci. 100, 93-1 18). Also, in early Alzheimer's disease (AD) brain, reduction of σ-1 R is detected.

Document WO2016138135 describes the neuroprotective effect of σ-I R agonists in a Huntington's disease cell model. The ability of these agonists to promote activation of pro- survival pathways was inhibited in the presence of selective σ-I R antagonists. All these findings suggest that the neuroprotective and neurorestorative actions of the σ-1 R provide a broad therapeutic window for σ-1 R agonists.

Because none of the studied σ-1 R agonists have been used in clinical so far, there is a need for alternative compounds for the treatment of age-related cognitive impairments. Surprisingly, the inventors of the present invention have found that inhibitors of σ-I R are effective compounds for the treatment of age-related cognitive impairments.

SUMMARY OF THE INVENTION

The inventors of the present invention have found that sigma-receptor ligands, in particular, sigma-1 receptor (σ-I R) ligands that are selective σ-I R antagonists, surprisingly are effective for the treatment of age-related cognitive impairments.

As it is shown in the Examples accompanying the present invention, the inventors have demonstrated that the cognitive responses of old wild type mice are significantly improved after chronic treatment with compound of Example 1 . Moreover, the cognitive responses of these old wild type mice treated with this compound were similar to the responses of old sigma-1 receptor heterozygous mice, i.e. mice carrying one single allele of the sigma-1 receptor, and consequently express about a -50% of the total amount of sigma-1 receptor.

Therefore, in a first aspect, the invention is directed to a sigma-1 receptor inhibitor for use in the treatment or prevention of age-related cognitive impairments. In a particular embodiment, said compound is selected from a sigma-1 receptor antagonist, a sigma-1 receptor neutral antagonist, a sigma-1 receptor inverse agonist and a sigma-1 receptor partial antagonist. In a preferred embodiment, said compound inhibiting the sigma-1 receptor for use in the treatment of an age-related cognitive impairment is a compound according to general formula (I):

(I)

wherein

Ri is selected from the group consisting of hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted non-aromatic heterocyclyl, substituted or unsubstituted aromatic heterocyclyl, substituted or unsubstituted heterocyclylalkyl, -COR₈, -C(0)OR₈, -C(0)NR₈R₉, -CH=NR₈, -CN, -OR₈, -OC(0)R₈, -S(0)_t-R₈, -NR₈R₉, -N R₈C(0)R₉, -N0₂, - N=CR₈R9, and halogen; R2 is selected from the group consisting of hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted, aromatic or non-aromatic heterocyclyl, substituted or unsubstituted heterocyclylalkyl, - COR₈, -C(0)OR₈, - C(0)NR₈R₉, -CH=NR₈, -CN, -OR₈, -OC(0)R₈, -S(0)_t-R₈, -N R₈R₉, -N R₈C(0)R₉,

-NO2, -N =CR₈R₉, and halogen ;

R3 and R₄ are independently selected from the group consisting of hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted, aromatic or non-aromatic heterocyclyl, substituted or unsubstituted heterocyclylalkyl, - CORs, -C(0)OR₈, -C(0)NR₈R₉, -CH=NR₈, -CN, -OR₈, -OC(0)R₈, -S(0)_t-R₈, -

NR₈Rg, -NR₈C(0)Rg, -NO2, -N=CR₈R9, and halogen, or together they form an optionally substituted fused ring system;

R5 and R6 are independently selected from the group consisting of hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted, aromatic or non-aromatic heterocyclyl, substituted or unsubstituted heterocyclylalkyl, - CORs, -C(0)OR₈, -C(0)NR₈R₉, -CH=NR₈, -CN, -OR₈, -OC(0)R₈, -S(0)_t-R₈, - NRsRg, -NR₈C(0)R₉, -NO2, -N=CR₈R₉, and halogen, or together form, with the nitrogen atom to which they are attached, a substituted or unsubstituted, aromatic or non-aromatic heterocyclyl group; n is selected from 1 , 2, 3, 4, 5, 6, 7 or 8; t is 1 ,2 or 3;

Re and Rg are each independently selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted, aromatic or non-aromatic heterocyclyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryloxy, and halogen; or a pharmaceutically acceptable salt, isomer, prodrug or solvate thereof.

In another aspect, the invention is directed to a compound inhibiting sigma-1 receptor, in particular those of general formula (I), for use as adjuvant therapy in the treatment of age- related cognitive impairment. In another aspect, the invention is directed to a pharmaceutical composition for use in the treatment of an age-related cognitive impairment comprising at least a compound as defined above, wherein the composition further comprises at least a pharmaceutically acceptable carrier, adjuvant and/or vehicle.

Another aspect of the invention refers to a method of treatment of a patient suffering from an age-related cognitive impairment, which comprises administering to the patient in need of such a treatment a therapeutically effective amount of a compound as defined above.

Another aspect of the invention refers to a method of treatment of a patient suffering from an age-related cognitive impairment, which comprises administering to the patient in need of such a treatment a therapeutically effective amount of a compound as defined above as adjuvant therapy.

These aspects and preferred embodiments thereof are additionally also defined in the claims.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 : Behavioural responses in the object recognition test in young and old wild-type mice (white columns) and young and old sigma-1 receptor heterozygous mice (grey columns) ^*** p<0.001 HET vs WT of corresponding age group (Two-way Anova + Bonferroni).

Figure 2: Sigma-1 receptor expression in the hippocampus of young and old wild-type mice (white columns) and young and old sigma-1 receptor heterozygous mice (grey columns). ^*** p<0.001 HET vs WT of corresponding age group (Two-way Anova + Bonferroni); # p<0.55 Old vs young of corresponding genotype group (Two-way Anova + Bonferroni).

Figure 3: Behavioral responses in the object recognition test in old wild type before and after treatment with Example 1 compound (white columns), old sigma-1 receptor heterozygous before and after treatment with Example 1 compound (greycolumns) and sigma-1 receptor heterozygous mice treated with saline (dashed column). ^***p<0.001 HET vs WT of corresponding age group (one-way Anova + Fisher's LSD test); # p<0.05 WT treated with Example 1 compound vs WT baseline value (before treatment). DETAILED DESCRIPTION OF THE INVENTION

As described above, the inventors have demonstrated that the impaired cognitive responses revealed in old wild type mice in a spatial working memory test (the object recognition paradigm) were not observed in old sigma-1 receptor heterozygous mice (Example 2). Mice carrying one single allele of the sigma-1 receptor (heterozygous mice) express about a ~50% of the total amount of sigma-1 receptor (Example 3). These results suggest that a reduction in the expression of sigma-1 receptor attenuates age-related cognitive deficits. In addition, as it is shown in the Example 4 below, the behavioural responses in the object recognition paradigm in wild type old animals treated with a compound according to the present invention are significantly improved. Thus, the results clearly show that the inhibition of sigma-1 receptor improves an age-related cognitive impairment. Thus, in a first aspect, the invention is directed to a sigma-1 receptor inhibitor, herein referred to as the "compound of the invention", for use in the treatment or prevention of an age-related cognitive impairment.

The term "sigma-1 receptor inhibitor" as used herein refers to any type of receptor ligand or drug that binds with high affinity to the sigma-receptor, preferably to the sigma-1 receptor (σ-1 R) subtype and blocks or dampens agonist-mediated responses. As an example, said σ-I R inhibitor is an antagonist. Antagonists have affinity but no efficacy for their cognate receptors, and binding will disrupt the interaction and inhibit the function of an agonist at receptors

Thus, in a particular embodiment of the invention, said inhibitor is selected from a sigma-1 receptor antagonist, a sigma-1 receptor neutral antagonist, a sigma-1 receptor inverse agonist and a sigma-1 receptor partial antagonist. In a more preferred embodiment, said inhibitor is a sigma-1 receptor antagonist.

The expression "binding with high affinity to the sigma receptor" refers to compounds of the invention that can replace a ligand in competitive binding assays, preferably in competitive radioligand-binding assays as exemplary described in WO2006/021462, e.g. in binding assays for the o1 -receptor performed as described (DeHaven-Hudkins et al., Eur J Pharmacol, 1992, 227, 371 ) or binding assays for o2-receptor as described (Radesca et al., J Med Chem,1991 , 34, 3058). Preferably, binding of the compounds of the invention, with respect to binding to the sigma-1 receptor subtype, is measured by competing with the binding of 3[H]-(+)-pentazocine, e.g. in radioligand-assays as described in the art (e.g. in DeHaven-Hudkins et al., 1992). Preferably, compounds of the invention when assayed at a concentration of 10-7M yield at least 25%, more preferably at least 45%, even more preferably at least 65%, yet even more preferably at least 75%, most preferably at least 85% binding to the sigma-1 receptor in 3[H]-(+)-pentazocine radioligand-assays as defined above.

The expression "binding selectively to the sigma-1 receptor" refers to compounds of the invention that shows nanomolar affinity for its target while showing either a percentage of inhibition less than 50% when tested at 1 micromolar in a panel of other non-specific targets or when there is one hundred times less affinity or functional activity for those non-specific targets. The term "age-related cognitive impairment" as used herein refers to the normal aging process in a subject and which is associated with declines in certain cognitive abilities, such as memory, attention, processing speed, visuospatial performance, executive functioning, and reasoning. Thus, in a particular embodiment, said age-related cognitive impairment refers to a cognitive ability which declines with age selected from the group consisting of memory, attention, processing speed, visuospatial performance, executive functioning, reasoning or combinations thereof.

As used herein, the term "treating age-related cognitive impairment" or "treatment of age- related cognitive impairment" refers to one or more of the following:

(1 ) inhibiting the disease and its progression; for example, inhibiting a disease, condition or disorder in an individual who is experiencing or displaying the pathology or symptomatology of the disease, condition or disorder (i.e., arresting further development of the pathology and/or symptomatology) such as in case of age- related cognitive impairment, arresting or delaying a) the decline in memory (long term and/or short term); b) the decline in attentional control (e.g. simple and divided attention); c) the decline in processing speed (e.g. language skills, decision making); d) the decline in visuospatial skills; e) the decline in executive functions (e.g. problem-solving, planning); and f) the decline in reasoning, and

(2) ameliorating the disease; for example, ameliorating a disease, condition or disorder in an individual who is experiencing or displaying the pathology or symptomatology of the disease, condition or disorder (i.e., reversing the pathology or symptomatology) such as in case of age-related cognitive impairment, a) improvement in memory (long term and/or short term); b) improvement in attentional control (e.g. simple and divided attention); c) improvement in processing speed (e.g. language skills, decision making); d) improvement in visuospatial skills; e) improvement in executive functions (e.g. problem-solving, planning); and f) improvement in reasoning.

Thus, in a particular embodiment of the invention, said age-related cognitive impairment is selected from the group consisting of memory impairment, attention impairment, processing speed impairment, visuospatial performance impairment, executive functioning impairment, reasoning impairment and combinations thereof. In a more particular embodiment, said age-related cognitive impairment is memory impairment.

In a preferred embodiment of the invention, the compound inhibiting the sigma-receptor, preferably the sigma-1 receptor subtype, for use in the treatment of age-related cognitive impairment is a compound according to formula I:

(I) wherein

Ri is selected from the group consisting of hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted non-aromatic heterocyclyl, substituted or unsubstituted aromatic heterocyclyl, substituted or unsubstituted heterocyclylalkyl, -CORs, -C(0)ORs, -C(0)NR₈R₉, -CH=NR₈, -CN, -OR₈, -OC(0)R₈, -S(0)_t-R₈, -NR₈R₉, -N R₈C(0)R₉, -N0₂, - N=CR₈R9, and halogen;

R2 is selected from the group consisting of hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted arylalkyi, substituted or unsubstituted, aromatic or non-aromatic heterocyclyl, substituted or unsubstituted heterocyclylalkyl, - COR₈, -C(0)OR₈, - C(0)NR₈R₉, -CH=NR₈, -CN, -OR₈, -OC(0)R₈, -S(0)_t-R₈, -N R₈R₉, -N R₈C(0)R₉, -NO2, -N =CR₈R₉, and halogen;

R3 and R₄ are independently selected from the group consisting of hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted arylalkyi, substituted or unsubstituted, aromatic or non-aromatic heterocyclyl, substituted or unsubstituted heterocyclylalkyl, - CORs, -C(0)OR₈, -C(0)NR₈R₉, -CH=NR₈, -CN , -OR₈, -OC(0)R₈, -S(0)_t-R₈, - N R₈R₉, -N R₈C(0)R₉, -NO2, -N=CR₈R₉, and halogen, or together they form an optionally substituted fused ring system;

R5 and R6 are independently selected from the group consisting of hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted arylalkyi, substituted or unsubstituted, aromatic or non-aromatic heterocyclyl, substituted or unsubstituted heterocyclylalkyl, -

CORs, -C(0)OR₈, -C(0)NR₈R₉, -CH=NR₈, -CN , -OR₈, -OC(0)R₈, -S(0)_t-R₈, - NR₈R₉, -NR₈C(0)R₉, -NO2, -N=CR₈R₉, and halogen, or together form, with the nitrogen atom to which they are attached, a substituted or unsubstituted, aromatic or non-aromatic heterocyclyl group; n is selected from 1 , 2, 3, 4, 5, 6, 7 or 8;

t is 1 ,2 or 3;

In a preferred embodiment of the use as defined above the compound is characterized in that Ri selected from H, -CORs, or substituted or unsubstituted alkyl, preferably it is selected from H, methyl or acetyl. In a preferred embodiment of the use as defined above the compound is characterized in that Ri is hydrogen.

In a preferred embodiment of the use as defined above the compound is characterized in that R2 is H or alkyl, preferably methyl or H.

In a preferred embodiment of the use as defined above the compound is characterized in that R3 and R₄ are situated in the meta and para positions of the phenyl group.

In a preferred embodiment of the use as defined above the compound is characterized in that R3 and R₄ are independently selected from halogen, or substituted or unsubstituted alkyl, more preferably selected from halogen or haloalkyl.

In an especially preferred embodiment of the use as defined above the compound is characterized in that both R3 and R₄ together with the phenyl group form an optionally substituted fused ring system. More preferably, said fused ring system is selected from a substituted or unsubstituted fused aryl group and a substituted or unsubstituted aromatic or partially aromatic fused heterocyclyl group. Said fused ring system preferably contains two rings and/or from 9 to about 18 ring atoms, more preferably 9 or 10 ring atoms. Even more preferably, the fused ring system is naphthyl, especially a 2-naphthyl ring system, substituted or unsubstituted.

In a preferred embodiment of the use as defined above the compound is characterized in that n is selected from 2, 3, 4, more preferably n is 2. In a preferred embodiment of the use as defined above the compound is characterized in that R₅ and R6, together, form a morpholin-4-yl group. In a preferred variant of the invention the sigma ligand of general formula (I) is selected from:

[1 ] 4-{2-(1 -(3,4-Dichlorophenyl)-5-methyl-1 H pyrazol-3-yloxy)ethyl} morpholine, [2] 2-[1 -(3,4-Dichlorophenyl)-5-methyl-1 H-pyrazol-3-yloxy]-N,N-diethylethanamine hydrochloride,

[3] 1 -(3,4-Dichlorophenyl)-5-methyl-3-[2-(pyrrolidin-1 -yl)ethoxy]-1 H-pyrazole hydrochloride,

[4] 1 -(3,4-Dichlorophenyl)-5-methyl-3-[3-(pyrrolidin-1 -yl)propoxy]-1 H-pyrazole hydrochloride,

[5] 1 -{2-[1 -(3,4-Dichlorophenyl)-5-methyl-1 H-pyrazol-3-yloxy]ethyl}piperidine,

[6] 1 -{2-[1 -(3,4-dichlorophenyl)-5-methyl-1 H-pyrazol-3-yloxy]ethyl}-1 H-imidazole, [7] 3-{1 -[2-(1 -(3,4-Dichlorophenyl)-5-methyl-1 H-pyrazol-3-yloxy)ethyl]piperidin-4-yl}- 3H-imidazo[4,5-b]pyridine,

[8] 1 -{2-[1 -(3,4-Dichlorophenyl)-5-methyl-1 H-pyrazol-3-yloxy]ethyl}-4- methylpiperazine,

[9] Ethyl 4-{2-[1 -(3,4-dichlorophenyl)-5-methyl-1 H-pyrazol-3-yloxy]ethyl}piperazine carboxylate,

[10] 1 -(4-(2-(1 -(3,4-dichlorophenyl)-5-methyl-1 H-pyrazol-3-yloxy)ethyl)piperazin-1 - yl)ethanone,

[1 1 ] 4-{2-[1 -(4-Methoxyphenyl)-5-methyl-1 H-pyrazol-3-yloxy]ethyl}morpholine hydrochloride,

[12] 1 -(4-Methoxyphenyl)-5-methyl-3-[2-(pyrrolidin-1 -yl)ethoxy]-1 H-pyrazole,

[13] 1 -(4-Methoxyphenyl)-5-methyl-3-[3-(pyrrolidin-1 -yl)propoxy]-1 H-pyrazole,

[14] 1 -[2-(1 -(4-Methoxyphenyl)-5-methyl-1 H-pyrazol-3-yloxy)ethyl]piperidine,

[15] 1 -{2-[1 -(4-Methoxyphenyl)-5-methyl-1 H-pyrazol-3-yloxy]ethyl}-1 H-imidazole, [16] 4-{2-[1 -(3,4-Dichlorophenyl)-5-phenyl-1 H-pyrazol-3-yloxy]ethyl}morpholine hydrochloride,

[17] 1 -(3,4-Dichlorophenyl)-5-phenyl-3-[2-(pyrrolidin-1 -yl)ethoxy]-1 H-pyrazole hydrochloride,

[18] 1 -(3,4-Dichlorophenyl)-5-phenyl-3-[3-(pyrrolidin-1 -yl)propoxy]-1 H-pyrazole,

[19] 1 -{2-[1 -(3,4-Dichlorophenyl)-5-phenyl-1 H-pyrazol-3-yloxy]ethyl}piperidine,

[20] 1 -{2-[1 -(3,4-Dichlorophenyl)-5-phenyl-1 H-pyrazol-3-yloxy]ethyl}-1 H-imidazole hydrochloride,

[21 ] 2-{2-[1 -(3,4-dichlorophenyl)-5-phenyl-1 H-pyrazol-3-yloxy]ethyl}-1 ,2,3,4- tetrahydroisoquinoline hydrochloride, [22] 4-{4-[1 -(3,4-Dichlorophenyl)-5-methyl-1 H-pyrazol-3-yloxy]butyl}morpholine hydrochloride,

[23] 1 -(3,4-Dichlorophenyl)-5-methyl-3-[4-(pyrrolidin-1 -yl)butoxy]-1 H-pyrazole,

[24] 1 -{4-[1 -(3,4-Dichlorophenyl)-5-methyl-1 H-pyrazol-3-yloxy]butyl}piperidine hydrochloride,

[25] 1 -{4-[1 -(3,4-Dichlorophenyl)-5-methyl-1 H-pyrazol-3-yloxy]butyl}-4- methylpiperazine dihydrochloride,

[26] 1 -{4-[1 -(3,4-Dichlorophenyl)-5-methyl-1 H-pyrazol-3-yloxy]butyl}-1 H-imidazole, [27] 4-[1 -(3,4-Dichlorophenyl)-5-methyl-1 H-pyrazol-3-yloxy]-N,N-diethylbutan-1 - amine,

[28] 1 -{4-[1 -(3,4-dichlorophenyl)-5-methyl-1 H-pyrazol-3-yloxy]butyl}-4- phenylpiperidine hydrochloride,

[29] 1 -{4-[1 -(3,4-dichlorophenyl)-5-methyl-1 H-pyrazol-3-yloxy]butyl}-6,7-dihydro-1 H- indol-4(5H)-one,

[30] 2-{4-[1 -(3,4-dichlorophenyl)-5-methyl-1 H-pyrazol-3-yloxy]butyl}-1 ,2,3,4- tetrahydroisoquinoline,

[31 ] 4-{2-[1 -(3,4-dichlorophenyl)-5-isopropyl-1 H-pyrazol-3-yloxy]ethyl}morpholine hydrochloride,

[32] 2-[1 -(3,4-Dichlorophenyl)-5-isopropyl-1 H-pyrazol-3-yloxy]-N,N-diethylethanamine, [33] 1 -(3,4-Dichlorophenyl)-5-isopropyl-3-[2-(pyrrolidin-1 -yl)ethoxy]-1 H-pyrazole hydrochloride,

[34] 1 -(3,4-Dichlorophenyl)-5-isopropyl-3-[3-(pyrrolidin-1 -yl)propoxy]-1 H-pyrazole hydrochloride,

[35] 1 -{2-[1 -(3,4-Dichlorophenyl)-5-isopropyl-1 H-pyrazol-3-yloxy]ethyl}piperidine, [36] 2-{2-[1 -(3,4-dichlorophenyl)-5-isopropyl-1 H-pyrazol-3-yloxy]ethyl}-1 ,2,3,4- tetrahydroisoqui-noline hydrochloride,

[37] 4-{2-[1 -(3,4-dichlorophenyl)-1 H-pyrazol-3-yloxy]ethyl}morpholine,

[38] 2-[1 -(3,4-dichlorophenyl)-1 H-pyrazol-3-yloxy] N,N-diethylethanamine,

[39] 1 -(3,4-dichlorophenyl)-3-[2-(pyrrolidin-1 -yl)ethoxy]-1 H-pyrazole,

[40] 1 -{2-[1 -(3,4-dichlorophenyl)-1 H-pyrazol-3-yloxy]ethyl}piperidine,

[41] 1 -(3,4-dichlorophenyl)-3-[3-(pyrrolidin-1 -yl)propoxy]-1 H-pyrazole,

[42] 1 -{2-[1 -(3,4-Dichlorophenyl)-5-methyl-1 H-pyrazol-3-yloxy]ethyl}piperazine dihydrochloride,

[43] 1 -{2-[1 -(3,4-Dichlorophenyl)-5-methyl-1 H-pyrazol-3-yloxy]ethyl}pyrrolidin-3- amine,

[44] 4-{2-[1 -(3,4-Dichlorophenyl)-4,5-dimethyl-1 H-pyrazol-3-yloxy]ethyl}morpholine, [45] 2-[1 -(3_!4-Dichlorophenyl)-4_!5-dimethyl-1 H-pyrazol-3-yloxy]-N,N- diethylethanamine hydrochloride,

[46] 1 -(3,4-Dichlorophenyl)-4,5-dimethyl-3-[2-(pyrrolidin-1 -yl)ethoxy]-1 H-pyrazole hydrochloride,

[47] 1 -(3,4-Dichlorophenyl)-4,5-dimethyl-3-[3-(pyrrolidin-1 -yl)propoxy]-1 H-pyrazole hydrochloride,

[48] 1 -{2-[1 -(3,4-Dichlorophenyl)-4,5-dimethyl-1 H-pyrazol-3-yloxy]ethyl}piperidine, [49] 4-{4-[1 -(3,4-dichlorophenyl)-1 H-pyrazol-3-yloxy]butyl}morpholine hydrochloride, [50] (2S,6R)-4-{4-[1 -(3,4-dichlorophenyl)-1 H-pyrazol-3-yloxy]butyl}-2,6- dimethylmorpholine hydrochloride,

[51 ] 1 -{4-[1 -(3,4-Dichlorophenyl)-1 H-pyrazol-3-yloxy]butyl}piperidine hydrochloride, [52] 1 -(3,4-Dichlorophenyl)-3-[4-(pyrrolidin-1 -yl)butoxy]-1 H-pyrazole hydrochloride, [53] 4-[1 -(3,4-dichlorophenyl)-1 H-pyrazol-3-yloxy]-N,N-diethylbutan-1 -amine oxalate, [54] N-benzyl-4-[1 -(3,4-dichlorophenyl)-1 H-pyrazol-3-yloxy]-N-methylbutan-1 -amine oxalate,

[55] 4-[1 -(3,4-dichlorophenyl)-1 H-pyrazol-3-yloxy]-N-(2-methoxyethyl)-N-methylbutan- 1 -amine oxalate,

[56] 4-{4-[1 -(3,4-dichlorophenyl)-1 H-pyrazol-3-yloxy]butyl}thiomorpholine oxalate, [57] 1 -[1 -(3,4-Dichlorophenyl)-5-methyl-3-(2-morpholinoethoxy)-1 H-pyrazol-4- yl]ethanone oxalate,

[58] 1 -{1 -(3,4-dichlorophenyl)-5-methyl-3-[2-(pyrrolidin-1 -yl)ethoxy]-1 H-pyrazol-4- yl}ethanone oxalate,

[59] 1 -{1 -(3,4-dichlorophenyl)-5-methyl-3-[2-(piperidin-1 -yl)ethoxy]-1 H-pyrazol-4- yl}ethanone oxalate,

[60] 1 -{1 -(3,4-dichlorophenyl)-3-[2-(diethylamino)ethoxy]-5-methyl-1 H-pyrazol-4- yl}ethanone oxalate,

[61] 4-{2-[5-Methyl-1 -(naphthalen-2-yl)-1 H-pyrazol-3-yloxy]ethyl}morpholine,

[62] N,N-Diethyl-2-[5-methyl-1 -(naphthalen-2-yl)-1 H-pyrazol-3-yloxy]ethanamine,

[63] 1 -{2-[5-Methyl-1 -(naphthalen-2-yl)-1 H-pyrazol-3-yloxy]ethyl}piperidine

hydrochloride,

[64] 5-Methyl-1 -(naphthalen-2-yl)-3-[2-(pyrrolidin-1-yl)ethoxy]-1 H-pyrazole

hydrochloride, their salts, different alternative pharmaceutically acceptable salts, solvates or prodrugs. In a more preferred embodiment of the use as defined above the compound is 4-{2-[5- methyl-1 -(naphthalen-2-yl)-1 H-pyrazol-3-yloxy]ethyl}morpholine or its pharmaceutically acceptable salts, solvates or a prodrug thereof. In a still more preferred embodiment of the use as defined above the compound is 4-{2-[5- methyl-1 -(naphthalen-2-yl)-1 H-pyrazol-3-yloxy]ethyl}morpholine hydrochloride or solvates or a prodrug thereof.

The term "alkyl" as used herein refers to a straight or branched hydrocarbon chain radical consisting of carbon and hydrogen atoms, containing no saturation, having one to eight carbon atoms, and which is attached to the rest of the molecule by a single bond, e. g., methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyl, n-pentyl, etc. Alkyl radicals may be optionally substituted by one or more substituents such as a aryl, halo, hydroxy, alkoxy, carboxy, cyano, carbonyl, acyl, alkoxycarbonyl, amino, nitro, mercapto, alkylthio, etc. If substituted by aryl it corresponds to an "arylalkyl or aralkyl" radical, such as benzyl and phenethyl.

The term "alkenyl" as used herein refers to an alkyl radical having at least two carbon atoms and having one or more unsaturated bonds.

The term "cycloalkyl" as used herein refers to a stable 3-to 10-membered monocyclic or bicyclic radical which is saturated or partially saturated, and which consist solely of carbon and hydrogen atoms, such as cyclohexyl or adamantyl. The cycloalkyl radicalmay be optionally substituted by one or more substituents such as alkyl, halo, hydroxy, amino, cyano, nitro, alkoxy, carboxy, alkoxycarbonyl, etc.

The term "aryl" as used herein refers to single and multiple ring radicals, including multiple ring radicals that contain separate and/or fused aryl groups. Typical aryl groups contain from 1 to 3 separated or fused rings and from 6 to about 18 carbon ring atoms, such as phenyl, naphthyl, indenyl, fenanthryl or anthracyl radical. The aryl radical may be optionally substituted by one or more substituents such as hydroxy, mercapto, halo, alkyl, phenyl, alkoxy, haloalkyl, nitro, cyano, dialkylamino, aminoalkyl, acyl, alkoxycarbonyl, etc.

The term "heterocyclyl" as used herein refers to a stable 3-to 15 membered ring radical which consists of carbon atoms and from one to five heteroatoms selected from the group consisting of nitrogen, oxygen, and sulfur, preferably a 4-to 8-membered ring with one or more heteroatoms, more preferably a 5-or 6-membered ring with one or more heteroatoms. It may be aromatic or not aromatic. For the purposes of this invention, the heterocycle may be a monocyclic, bicyclic or tricyclic ring system, which may include fused ring systems; and the nitrogen, carbon or sulfur atoms in the heterocyclyl radical may be optionally oxidised; the nitrogen atom may be optionally quaternized ; and the heterocyclyl radical may be partially or fully saturated or aromatic. Examples of such heterocycles include, but are not limited to, azepines, benzimidazole, benzothiazole, furan, isothiazole, imidazole, indole, piperidine, piperazine, purine, quinoline, thiadiazole, tetrahydrofuran, coumarine, morpholine; pyrrole, pyrazole, oxazole, isoxazole, triazole, imidazole, etc.

The term "alkoxy" as used herein refers to a radical of the formula -ORa where Ra is an alkyl radical as defined above, e.g., methoxy, ethoxy, propoxy, etc.

The term "amino" as used herein refers to a radical of the formula-Nhb, -NHRa or -NRaRb, optionally quaternized, wherein Ra and Rb is an alkyl radical as defined above, e.g., methoxy, ethoxy, propoxy, etc.

The terms "halo" or "hal" as used herein refer to bromo, chloro, iodo or fluoro. The term "fused ring system" as used herein refers to a polycyclic ring system that contains fused rings. Typically, the fused ring system contains 2 or 3 rings and/or up to 18 ring atoms. As defined above, cycloalkyl radicals, aryl radicals and heterocyclyl radicals may form fused ring systems. Thus, fused ring system may be aromatic, partially aromatic or not aromatic and may contain heteroatoms. A spiro ring system is not a fused-polycyclic by this definition, but fused polycyclic ring systems of the invention may themselves have spiro rings attached thereto via a single ring atom of the system. Examples of fused ring systems are, but are not limited to, adamantyl, naphthyl (e.g. 2-naphthyl), indenyl, fenanthryl, anthracyl, pyrenyl, benzimidazole, benzothiazole, etc. Unless otherwise stated specifically in the specification, all the groups may be optionally substituted, if applicable. References herein to substituted groups in the compounds of the present invention refer to the specified moiety that may be substituted at one or more available positions by one or more suitable groups, e. g., halogen such as fluoro, chloro, bromo and iodo ; cyano; hydroxyl ; nitro ; azido ; alkanoyl such as a Ci-6 alkanoyl group such as acyl and the like; carboxamido; alkyl groups including those groups having 1 to about 12 carbon atoms or from 1 to about 6 carbon atoms and more preferably 1 -3 carbon atoms; alkenyl and alkynyl groups including groups having one or more unsaturated linkages and from 2 to about 12 carbon or from 2 to about 6 carbon atoms; alkoxy groups having one or more oxygen linkages and from 1 to about 12 carbon atoms or 1 to about 6 carbon atoms; aryloxy such as phenoxy; alkylthio groups including those moieties having one or more thioether linkages and from 1 to about 12 carbon atoms or from 1 to about 6 carbon atoms; alkylsulfinyl groups including those moieties having one or more sulfinyl linkages and from 1 to about 12 carbon atoms or from 1 to about 6 carbon atoms ; alkylsulfonyl groups including those moieties having one or more sulfonyl linkages and from 1 to about 12 carbon atoms or from 1 to about 6 carbon atoms; aminoalkyl groups such as groups having one or more N atoms and from 1 to about 12 carbon atoms or from 1 to about 6 carbon atoms; carbocylic aryl having 6 or more carbons, particularly phenyl or naphthyl and aralkyi such as benzyl. Unless otherwise indicated, an optionally substituted group may have a substituent at each substitutable position of the group, and each substitution is independent of the other.

Unless otherwise stated, the compounds of the invention are also meant to include compounds which differ only in the presence of one or more isotopically enriched atoms. For example, compounds having the present structures except for the replacement of a hydrogen by a deuterium or tritium, or the replacement of a carbon by a ¹³C- or ¹⁴C-enriched carbon or ¹⁵N-enriched nitrogen are within the scope of this invention.

The term "pharmaceutically acceptable salts, solvates, prodrugs" refers to any pharmaceutically acceptable salt, ester, solvate, or any other compound which, upon administration to the recipient is capable of providing (directly or indirectly) a compound as described herein. However, it will be appreciated that non-pharmaceutically acceptable salts also fall within the scope of the invention since those may be useful in the preparation of pharmaceutically acceptable salts. The preparation of salts, prodrugs and derivatives can be carried out by methods known in the art. For instance, pharmaceutically acceptable salts of compounds provided herein are synthesized from the parent compound which contains a basic or acidic moiety by conventional chemical methods. Generally, such salts are, for example, prepared by reacting the free acid or base forms of these compounds with a stoichiometric amount of the appropriate base or acid in water or in an organic solvent or in a mixture of the two. Generally, nonaqueous media like ether, ethyl acetate, ethanol, isopropanol or acetonitrile are preferred. Examples of the acid addition salts include mineral acid addition salts such as, for example, hydrochloride, hydrobromide, hydroiodide, sulphate, nitrate, phosphate, and organic acid addition salts such as, for example, acetate, maleate, fumarate, citrate, oxalate, succinate, tartrate, malate, mandelate, methanesulphonate and p- toluenesulphonate. Examples of the alkali addition salts include inorganic salts such as, for example, sodium, potassium, calcium, ammonium, magnesium, aluminium and lithium salts, and organic alkali salts such as, for example, ethylenediamine, ethanolamine, N,N- dialkylenethanolamine, triethanolamine, glucamine and basic aminoacids salts.

Particularly favored derivatives or prodrugs are those that increase the bioavailability of the compounds of this invention when such compounds are administered to a patient (e.g., by allowing an orally administered compound to be more readily absorbed into the blood) or which enhance delivery of the parent compound to a biological compartment (e.g., the brain or lymphatic system) relative to the parent species. Any compound that is a prodrug of a compound of formula (I) is within the scope of the invention. The term "prodrug" is used in its broadest sense and encompasses those derivatives that are converted in vivo to the compounds of the invention. Such derivatives would readily occur to those skilled in the art, and include, depending on the functional groups present in the molecule and without limitation, the following derivatives of the present compounds: esters, amino acid esters, phosphate esters, metal salts sulfonate esters, carbamates, and amides. Examples of well known methods of producing a prodrug of a given acting compound are known to those skilled in the art and can be found e.g. in Krogsgaard-Larsen et al. "Textbook of Drug design and Discovery" Taylor & Francis (april 2002).

The compounds of the invention may be in crystalline form either as free compounds or as solvates and it is intended that both forms are within the scope of the present invention. Methods of solvation are generally known within the art. Suitable solvates are pharmaceutically acceptable solvates. In a particular embodiment the solvate is a hydrate.

The compounds of general formula (I) or their salts or solvates are preferably in pharmaceutically acceptable or substantially pure form. By pharmaceutically acceptable form is meant, inter alia, having a pharmaceutically acceptable level of purity excluding normal pharmaceutical additives such as diluents and carriers, and including no material considered toxic at normal dosage levels. Purity levels for the drug substance are preferably above 50%, more preferably above 70%, most preferably above 90%. In a preferred embodiment it is above 95% of the compound of formula (I), or of its salts, solvates or prodrugs.

The compounds of the present invention represented by the above described general formula (I) may include enantiomers depending on the presence of chiral centres or isomers depending on the presence of multiple bonds (e.g. Z, E). The single isomers, enantiomers or diastereoisomers and mixtures thereof fall within the scope of the present invention.

The compounds of general formula (I) and their salts or solvates can be prepared according to the process disclosed in the document WO2006/021462.

The obtained reaction products may, if desired, be purified by conventional methods, such as crystallisation and chromatography. Where the above described processes for the preparation of compounds of the invention give rise to mixtures of stereoisomers, these isomers may be separated by conventional techniques such as preparative chromatography. If there are chiral centers the compounds may be prepared in racemic form, or individual enantiomers may be prepared either by enantiospecific synthesis or by resolution. One preferred pharmaceutically acceptable form is the crystalline form, including such crystalline form in pharmaceutical composition. In the case of salts and solvates the additional ionic and solvent moieties must also be non-toxic. The compounds of the invention may present different polymorphic forms, it is intended that the invention encompass all such forms. In a preferred embodiment, said polymorphic form is the polymorphic form of the hydrochloride salt of 4-{2-[5-Methyl-1 -(naphthalen-2-yl)-1 H- pyrazol-3-yloxy]ethyl} morpholine as described in WO201 1/095579.

As used herein, the terms "treat", "treating" and "treatment" include the eradication, removal, reversion, alleviation, modification, or control of age-related cognitive impairments and/or its related symptoms. More particularly, as used herein, the term "treating age-related cognitive impairment" or "treatment of age-related cognitive impairment" are as described above.

In a particular embodiment of the invention, the subject to be treated according to the invention is a subject 40 years of age or older, preferably 50 years of age or older, more preferably 60 years of age or older, even more preferably 65 years of age or older and still even more preferably 70 years of age or older.

Another aspect of this invention relates to a method of treating an age-related cognitive impairment, comprising administering to a patient in need of such a treatment a therapeutically effective amount of a compound of as defined above or a pharmaceutical composition thereof.

Another aspect of the invention is a method of treatment of a patient suffering from an age-related cognitive impairment, which comprises administering to the patient in need of such a treatment a therapeutically effective amount of a compound as defined above or a pharmaceutical composition of the invention as adjuvant therapy.

Another aspect of the invention is a method of treatment of a patient suffering from an age-related cognitive impairment, which comprises administering to the patient in need of such a treatment a therapeutically effective amount of a compound as defined above.

In another aspect, the invention is directed to a use of a sigma-1 receptor inhibitor, more particularly, a compound of general formula (I) as above defined in the preparation of a medicament for the treatment of age-related cognitive impairment.

In another aspect, the invention is directed to a use of a sigma-1 receptor inhibitor, more particularly, a compound of general formula (I) as above defined, in the preparation of a medicament for age-related cognitive impairment adjuvant therapy. The present invention further provides pharmaceutical compositions comprising a compound of this invention, or a pharmaceutically acceptable salt, derivative, prodrug or stereoisomers thereof together with a pharmaceutically acceptable carrier, adjuvant, or vehicle, for administration to a patient. In another particular embodiment, the invention refers to a pharmaceutical composition according to the invention for use in the treatment or prevention of an age-related cognitive impairment. In a more particular embodiment, the invention refers to a pharmaceutical composition for use in the treatment of an age-related cognitive impairment selected from the group consisting of memory impairment, attention impairment, processing speed impairment, visuospatial performance impairment, executive functioning impairment, reasoning impairment and combinations thereof. In a more preferred embodiment, said age- related cognitive impairment is memory impairment.

In another aspect, the invention is thus directed to the use as defined above of a pharmaceutical composition comprising a compound as defined above, wherein the composition further comprises a pharmaceutically acceptable carrier, adjuvant and/or vehicle.

Examples of pharmaceutical compositions include any solid (tablets, pills, capsules, granules etc.) or liquid (solutions, suspensions or emulsions) composition for oral, topical or parenteral administration.

In a preferred embodiment, the pharmaceutical compositions are in oral form, either solid or liquid. Suitable dose forms for oral administration may be tablets, capsules, syrops or solutions and may contain conventional excipients known in the art such as binding agents, for example syrup, acacia, gelatin, sorbitol, tragacanth, or polyvinylpyrrolidone; fillers, for example lactose, sugar, maize starch, calcium phosphate, sorbitol or glycine; tabletting lubricants, for example magnesium stearate; disintegrants, for example starch, polyvinylpyrrolidone, sodium starch glycollate or microcrystalline cellulose; or pharmaceutically acceptable wetting agents such as sodium lauryl sulfate.

The solid oral compositions may be prepared by conventional methods of blending, filling or tableting. Repeated blending operations may be used to distribute the active agent throughout those compositions employing large quantities of fillers. Such operations are conventional in the art. The tablets may for example be prepared by wet or dry granulation and optionally coated according to methods well known in normal pharmaceutical practice, in particular with an enteric coating.

The pharmaceutical compositions may also be adapted for parenteral administration, such as sterile solutions, suspensions or lyophilized products in the appropriate unit dosage form. Adequate excipients can be used, such as bulking agents, buffering agents or surfactants.

The mentioned formulations will be prepared using standard methods such as those described or referred to in the Spanish and US Pharmacopoeias and similar reference texts. Administration of the compounds or compositions of the present invention may be by any suitable method, such as intravenous infusion, oral preparations, and intraperitoneal and intravenous administration. Oral administration is preferred because of the convenience for the patient and the chronic character of the diseases to be treated.

Generally an effective administered amount of a compound of the invention will depend on the relative efficacy of the compound chosen, the severity of the disorder being treated and the weight of the sufferer. However, active compounds will typically be administered once or more times a day for example 1 , 2, 3 or 4 times daily, with typical total daily doses in the range of from 0.1 to 1000 mg/kg/day. In a preferred embodiment of the use of the compounds of the invention the compounds, optionally in the form of a pharmaceutical composition, are administered once daily.

In a preferred embodiment of the use of the compounds of the invention, the compound is administered as a daily dose of from to 100 mg to 600 mg per day. Even more preferably, the compound is administered as a daily dose of from 200 mg to 400 mg per day.

The compounds and compositions of this invention may be used to provide with other drugs a combination therapy. The other drugs may form part of the same composition, or be provided as a separate composition for administration at the same time or at different time. Advantageously, the other drugs are selected among the known drugs currently used in the treatment of age-related cognitive impairment.

The following examples are given only as further illustration of the invention; they should not be taken as a definition of the limits of the invention.

EXAMPLES

Example 1 The hydrochloride salt of compound 4-{2-[5-Methyl-1 -(naphthalen-2-yl)-1 H-pyrazol-3- yloxy]ethyl} morpholine has been prepared as disclosed in document WO201 1/064315:

1 H-NMR (DMSO-d6) 6 ppm: 10,85 (bs, 1 H), 7,95 (m, 4H), 7,7 (dd, J=2,2, 8,8 Hz,1 H), 7,55 (m, 2H), 5,9 (s, 1 H), 4,55 (m, 2H), 3,95 (m, 2H), 3,75 (m, 2H), 3,55-3,4 (m, 4H), 3,2 (m, 2H), 2,35 (s, 3H).

HPLC purity: 99.8%.

Example 2

Cognition response in old mice.

Materials and methods

Animals

Young (7-8 weeks) and old (20-24 months) sigma-1 receptor heterozygous mice and wild- type mice were used. Mice of the two genotypes were in a pure C57BI6/J congenic background. Mice were housed four per cage in a temperature (21 ± 1 °C) and humidity (55 ± 10 %) controlled environment. Food and water were available ad libitum. All the experiments were performed during the light phase of a 12 h light/dark cycle (lights on at 8 am and off at 8 pm). All animal procedures were conducted in accordance with the standard ethical guidelines (European Communities Directive 86/60-EEC) and approved by the local ethical committee (Comite Etic d'Experimentacio Animal, CEEA-PRBB). Our institution has also the Animal Welfare Assurance (#A5388-01 , IACUC Approval Date 06/08/2009) granted by the Office of Laboratory Animal Welfare (OLAW) of the National Institutes of Health (USA). All behavioral experiments were performed under blind conditions.

Object Recognition Paradigm

The object recognition paradigm evaluates spatial working memory with a predominant involvement of responses mediated by the hippocampus. Object recognition memory was assayed in the V-maze, a black Plexiglas maze with two corridors (30 cm long ^χ 4.5 cm wide) set in V with a 90° angle, and 15 cm high walls (Puighermanal et al., 2009). On day one, mice were habituated for 9 min to the maze where the task was performed. On the second day, mice were put back in the maze for 9 min where two identical objects were presented, and the time the animals spent exploring each object was recorded. Mice were put again (24 h later) in the maze for 9 min, where one of the familiar objects was changed for a novel object, and the total time spent exploring each of the two objects (novel and familiar) was computed. Object exploration was defined as the orientation of the nose to the object at a distance < 2 cm. A discrimination index was calculated as the difference between the time spent exploring the novel and familiar object divided by the total time exploring the two objects. High discrimination index is considered to reflect greater memory retention for the familiar object. The total exploration time was recorded as an indicator of the locomotor activity.

Experimental groups

The following experimental groups of young and old animals were tested in both cognitive paradigms:

Group 1 : Young wild-type mice (n = 10)

Group 2: Young sigma-1 receptor heterozygous mice (n = 1 1 )

Group 3: Old wild-type mice (n = 8)

Group 4: Old sigma-1 receptor heterozygous mice (n = 8)

Results

The cognitive responses of the young wild-type and sigma-1 receptor heterozygous mice were similar in the object recognition paradigm. However, the impaired cognitive response revealed in the old wild-type mice compared with the young wild-type mice was not observed in the old sigma-1 receptor heterozygous mice (Figure 1 ).

Example 3

Materials and methods

Gene expression using Quantitative Reverse Transcription-PCR

Total RNA was extracted from frozen hippocampus (groups 1 , 2, 3 and 4) using TRI reagent with Ribopure Kit (Ambion/Applied biosystems, Foster City, CA, USA). Thereafter, a two- step quantitative real-time PCR (RT-qPCR) was performed. RNA samples were converted into cDNA using a High Capacity cDNA Reverse Transcription Kit (Applied Biosystems). The PCR reaction mixture was incubated on the Bio-Rad CFX384 Touch Real-Time PCR Detection System (Bio-Rad). All samples were assayed in triplicate. The cycle thresholds for each sample were obtained and data were analysed using the comparative Ct method (2-AACt) with the WT vehicle group serving as the calibrator (Livak & Schmittgen, 201 1 ). TaqMan® gene expression assays (hydrolysis probes, Applied Biosystems) for o1 receptor (o1 R) (Mm00448086_m1 ) were used, β-2-microglobulin (Mm00437762_m1 ) was used as endogenous reference gene. Statistical analysis

Data are expressed as mean±SEM. A robust analysis (one iteration) was used to obtain mean±SEM for RT-qPCR data. Data were analysed by two-way ANOVA, followed, when necessary, by a Bonferroni's multiple comparisons test. Data were considered statistically significant when P< 0.05. All statistical analyses were performed using GraphPad Prism 6 (GraphPad Software, La Jolla, CA, USA).

Results

The sigma 1 receptor expression in the hippocampus was reduced by 50% in both young and old sigma-1 receptor heterozygous mice (Figure 2)

Example 4

Effects of Example 1 compound on the cognitive responses in old mice.

Materials and methods

The cognitive responses of sigma-1 receptor heterozygous and wild-type old mice were evaluated in the object recognition paradigm at basal conditions as well as 30 days after the chronic treatment with Example 1 compound.

Animals

Old (20-24 months) sigma-1 receptor heterozygous mice and wild-type mice were used. Mice of the two genotypes were in a pure C57BI6/J congenic background. Mice were housed four per cage in a temperature (21 ± 1 °C) and humidity (55 ± 10 %) controlled environment. Food and water were available ad libitum. All the experiments were performed during the light phase of a 12 h light/dark cycle (lights on at 8 am and off at 8 pm). All animal procedures were conducted in accordance with the standard ethical guidelines (European Communities Directive 86/60-EEC) and approved by the local ethical committee (Comite Etic d'Experimentacio Animal, CEEA-PRBB). All behavioral experiments were performed under blind conditions.

Object Recognition paradigm

The object recognition paradigm evaluates spatial working memory with a predominant involvement of responses mediated by the hippocampus. Object recognition memory was assayed in the V-maze, a black Plexiglas maze with two corridors (30 cm long ^χ 4.5 cm wide) set in V with a 90° angle, and 15 cm high walls (Puighermanal et al., 2009). On day one, mice were habituated for 9 min to the maze where the task was performed. On the second day, mice were put back in the maze for 9 min where two identical objects were presented, and the time the animals spent exploring each object was recorded. 24 hours later, mice were put again in the maze for 9 min, where one of the familiar objects was changed for a novel object, and the total time spent exploring each of the two objects (novel and familiar) was computed. Object exploration was defined as the orientation of the nose to the object at a distance < 2 cm. A discrimination index was calculated as the difference between the time spent exploring the novel and familiar object divided by the total time exploring the two objects. High discrimination index is considered to reflect greater memory retention for the familiar object. The total exploration time was recorded as an indicator of the locomotor activity.

Compound administration

The drug as described in Example 1 was dissolved in hydroxypropyl methylcellulose 0.5 % and administered intraperitoneously (i.p.). A dose of 20 mg/kg twice a day was administered in old sigma-1 receptor heterozygous mice and wild-type mice during 30 days.

Experimental groups

The following experimental groups were tested in the cognitive paradigm:

Group 1 : Old (20-24 months) wild-type mice (n = 10) treated with compound of Example 1 .

Group 2: Old (20-24 months) sigma-1 receptor heterozygous mice (n = 12) treated with compound of Example 1 .

Group 3: Old (20-24 months) sigma-1 receptor heterozygous mice (n = 4) treated with Saline.

Statistical analysis

Data are expressed as mean ± SEM, and were compared by using a one-way ANOVA (genotype as between group factors) followed by subsequent post-hoc analysis (Fisher's LSD test) when appropriate. Statistical significance criterion was P < 0.05.

Results: Effects of chronic administration of compound of Example 1 (20 mg/kg twice a day) on novel object recognition paradigm in old wild type mice.

One-way ANOVA revealed a significant improvement of cognitive performance in the old sigma-1 receptor heterozygous mice compared to wild-type animals before starting the chronic treatment, as revealed by a significantly higher discrimination index in the novel object recognition paradigm (p < 0.001 ).

A significant increase in the discrimination index was revealed in old wild-type mice (p < 0.5) after 30 days of chronic administration of compound of Example 1 (20 mg/kg twice daily) when compared to the cognitive performance before treatment, indicating a cognitive improvement promoted by this chronic treatment in old wild type mice. No significant differences were observed in the discrimination index in old sigma-1 receptor heterozygous mice before and after chronic treatment with S1 RA or vehicle. Interestingly, the discrimination index of old wild type after chronic treatment with compound of Example 1 was similar to old sigma-1 receptor heterozygous mice (Figure 3).

Conclusions

1 . Impaired cognitive responses were revealed in old wild-type mice compared with young wild-type mice in the object recognition paradigm before receiving the chronic treatments. This memory impairment was not observed in old sigma-1 receptor heterozygous mice (Example 2), which expressed approximately half of the wild-type amount of sigma-1 receptor expression (Example 3), suggesting a protective role of this receptor on the cognitive deficit produced by ageing.

2. The cognitive responses of old wild type mice were significantly improved after chronic treatment with compound of Example 1 (20 mg/kg twice daily) during 30 days (Example 4). The cognitive responses of these old wild type mice treated with compound of Example 1 were similar to the responses of old sigma-1 receptor heterozygous mice.

3. The cognitive responses of old sigma-1 receptor heterozygous mice were not significantly modified after chronic treatment with compound of Example 1 (20 mg/kg twice daily) during 30 days.

4. In summary, the constitutive single allele deletion of the sigma-1 receptor (heterozygous mice, Example 2), which showed a reduction in the expression of sigma-1 receptor (Example 3), and/or the chronic treatment with compound of Example 1 improved the cognitive responses in old mice (Example 4), suggesting that sigma-1 receptor is a possible novel target for protective effects on the cognitive impairment produced by ageing.

References

Puighermanal E, Marsicano G, Busquets-Garcia A, Lutz B, Maldonado R, Ozaita A. Cannabinoid modulation of hippocampal long-term memory is mediated by mTOR signaling. Nature Neuroscience. 12, 1 152-1 158 (2009).

Claims

A sigma-1 receptor inhibitor for use in the treatment or prevention of an age-related cognitive impairment.

The sigma-1 receptor inhibitor for use according to claim 1 , wherein said inhibitor is selected from a sigma-1 receptor antagonist, a sigma-1 receptor neutral antagonist, a sigma-1 receptor inverse agonist and a sigma-1 receptor partial antagonist.

The sigma-1 receptor inhibitor for use according to claim 1 or 2 wherein said compound has the general formula (I):

(I) wherein

Ri is selected from the group consisting of hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyi, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted non- aromatic heterocyclyl, substituted or unsubstituted aromatic heterocyclyl, substituted or unsubstituted heterocyclylalkyl, -COR₈, -C(0)OR₈, -C(0)NR₈R₉, -CH=NR₈, -CN, -OR₈, - OC(0)R₈, -S(0)t-R₈, -NR₈R₉, -NR₈C(0)R₉, -N0₂, - N=CR₈R₉, and halogen;

R2 is selected from the group consisting of hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyi, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted, aromatic or non-aromatic heterocyclyl, substituted or unsubstituted heterocyclylalkyl, - CORs, -C(0)OR₈, -C(0)NR₈R₉, -CH=NR₈, -CN, -OR₈, -OC(0)R₈, -S(0)t-R₈, -N R₈R₉, - N R₈C(0)R₉, -NO2, -N =CR₈R₉, and halogen; R3 and R₄ are independently selected from the group consisting of hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted, aromatic or non-aromatic heterocyclyl, substituted or unsubstituted heterocyclylalkyl, -COR₈, -C(0)OR₈, -C(0)NR₈R₉, -CH=NR₈, -CN , -OR₈, -OC(0)R₈, -S(0)t- R₈, -N R₈R₉, -NR₈C(0)R₉, -NO2, -N=CR₈R₉, and halogen, or together they form an optionally substituted fused ring system;

R5 and R6 are independently selected from the group consisting of hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted arylalkyl, substituted or unsubstituted, aromatic or non-aromatic heterocyclyl, substituted or unsubstituted heterocyclylalkyl, -COR₈, -C(0)OR₈, -C(0)NR₈R₉, -CH=NR₈, -CN, -OR₈, -OC(0)R₈, -S(0)t- R₈, -NR₈R₉, -N R₈C(0)R₉, -NO2, -N=CR₈R₉, and halogen, or together form, with the nitrogen atom to which they are attached, a substituted or unsubstituted, aromatic or non-aromatic heterocyclyl group; n is selected from 1 ,

2,

3, 4, 5, 6, 7 or 8; t is 1 ,2 or 3;

4. The sigma-1 receptor inhibitor for use according to claim 3, wherein the compound is characterized in that Ri is hydrogen.

5. The sigma-1 receptor inhibitor for use according to any of claims 3 or 4, wherein the compound is characterized in that R2 is H or alkyl, preferably methyl or H.

6. The sigma-1 receptor inhibitor for use according to any of claims 3 to 5, wherein the compound is characterized in that R3 and R₄ together with the phenyl forms a naphthyl group.

7. The sigma-1 receptor inhibitor for use according to any of claims 3 to 6, wherein the compound is characterized in that n is selected from 2, 3, 4, more preferably n is 2.

8. The sigma-1 receptor inhibitor for use according to any of claims 3 to 7, wherein the compound is characterized in that R₅ and R6, together, form a morpholine-4-yl group.

9. The sigma-1 receptor inhibitor for use according to any of claims 3 to 8, wherein the compound is selected from 4-{2-[5-Methyl-1 -(naphthalen-2-yl)-1 H-pyrazol-3- yloxy]ethyl}morpholine or its pharmaceutically acceptable salts, solvates or a prodrug thereof and 4-{2-[5-Methyl-1 -(naphthalen-2-yl)-1 H-pyrazol-3- yloxy]ethyl}morpholine hydrochloride or solvates or a prodrug thereof.

10. The sigma-1 receptor inhibitor for use according to any one of claims 1 to 9, wherein said age-related cognitive impairment is selected from the group consisting of memory impairment, attention impairment, processing speed impairment, visuospatial performance impairment, executive functioning impairment, reasoning impairment and combinations thereof.

1 1 . The sigma-1 receptor inhibitor for use according to claim 10, wherein said age- related cognitive impairment is memory impairment.

12. A pharmaceutical composition comprising a sigma-1 receptor inhibitor according to any one of claims 1 to 1 1 for use in the treatment or prevention of an age-related cognitive impairment.

13. Pharmaceutical composition for use according to claim 12, wherein said age-related cognitive impairment is selected from the group consisting of memory impairment, attention impairment, processing speed impairment, visuospatial performance impairment, executive functioning impairment, reasoning impairment and combinations thereof.

14. Pharmaceutical composition for use according to claims 1 to 13, wherein the composition further comprises a pharmaceutically acceptable carrier, adjuvant and/or vehicle.

15. A sigma-1 receptor inhibitor for use according to any one of claims 1 to 1 1 or a pharmaceutical composition for use according to claims 12 or 13 for use as adjuvant therapy in the treatment of age-related cognitive impairment.