Patent Application
20050153981
This invention relates to aralkyl formylalkyl piperazine derivatives and their applications as a neuro-protective agent.
Cerebral accidents (such as stroke), especially ischemic apoplexy, is currently the third biggest cause of death. It is also the major factor that causes long-term loss of living abilities. In developed countries, strokes make up 10% of the death among men and 17% of the death among women. With the aging of population, it is predicted that there will be a rise of 13% in stroke patients during the next 3 years. Three fourths of stroke survivors will be disabled or dysfunctional, which results in highly increased medical cost and other serious social problems.
There are now two kinds of therapeutic medicines for the treatment of ischemic apoplexy:
The safety and efficiency of the first category of medicines are controversial, especially because of individual differences of patients. In particular, some of the drugs may cause unwanted bleeding aggravating ischemia and its symptoms and increasing the early stage mortality rate. Therefore, their clinical use has been limited.
The second category of medicines is neuroprotecting agents. Studies show that when the brain is in an ischemic state, Excitatory Amino Acid (EAA), a central neurotransmitter, is released in large amounts, acts on EAA receptors, mostly on the effector-comlex (N-methyl-D-aspartate receptor, NMDA receptor), and then opens the Ca2+ and Na2+ channels, changes the ion permeability, and causes imbalance of the ions inside and outside of the neural cells. This primarily will result in large in-flow the Ca2+ and Na2+, which causes swelling and death of nerve cells. In theory, if the activity of NMDA receptor is inhibited partly, the in-flow of Ca2+ can be reduced greatly, and then the ischemic brain injury induced by NMDA receptor will be effectively prevented.
Recent discoveries of different kinds of EAA receptor antagonists have enabled a new approach to treating ischemic brain injuries. Among them, NMDA receptor antagonists are the main candidates for developing new drugs for preventing and treating ischemic apoplexy. Many NMDA receptor antagonists such as GV-150526A, AR-R15896, ACEA-1021, and ZD-9379 are being tested in clinical phases.
NMDA receptor competitive antagonists have two acid groups and high polarity, and are hard to permeate the blood-brain barrier. Their oral bioavailability is low. The piperazine derivative CPP and its analogues are highly selective, strong receptor antagonists, can permeate the blood-brain barrier and have activity after oral administration (Fritz, K. I., Brain Res. 729(1) 66-74, 1996). Ly-274614 is now one of the most effective NMDA receptor competitive antagonists (Cheung, N. S., Eur. J. Pharmacol., 313(½), 159-162, 1996). However, the above-mentioned antagonists have low therapeutic index, with side effects such as damages to motor neuron.
Disjunctive anesthetics acting on cation channel such as PCP and MK-801 are all non-competitive antagonists. These non-competitive antagonists can easily permeate the blood brain barrier; however, they have low selectivity and serious toxicity. Thus they have no or little clinical value.
Since the 1990s, new compounds have been continuously entering clinical trials. It is a long and hard task in this research area to design and synthesize selective and effective NMDA receptor modulators, and the novel antagonists with the lowest psychic and mental toxicities. This task also has great social and economic values.
The first aspect of the present invention is to provide aralkyl formylalkyl piperazine derivatives which have medical value. The aim is to overcome the defects of some present anti-ischemic apoplexy agents, such as induced bleeding, difficulty on transmitting blood brain barrier, low oral bioavailability, low selectivity and high nervous and behavioral toxicities.
The second aspect of the present invention is to provide the application of the above aralkyl formylalkyl piperazine derivatives as neuroprotective agents, especially in the treatment of ischemic cerebral apoplexy.
The third aspect of the present invention is to supply pharmaceutical compositions for the treatment of ischemic cerebral apoplexy.
The aralkyl formylalkyl piperazine derivatives described in present invention are free base or salts of the compounds represented by the following general formula:
in which the salts are independently one of hydrochloride, hydrobromide, sulfate, trifluoroacetate or methanesulfonate, and preferably hydrochloride or hydrobromide. The salt can contain between 0.5-3 molecules of hydrate water.
In the above formula,
The preferable compounds are included as follows:
Particularly preferable is N1-phenacyl-N4-[2-(benzylamino)-2-oxo-ethyl] piperazine.
Their structures are shown in Table 1.
The above-mentioned compounds can be prepared by the following two synthetic routes.
Synthetic route 1:
Synthetic route 2:
Piperazine is used as a starting material to prepare the above-mentioned compounds. The N atom of the piperazine ring is protected by formyl group first, and then alkylated, finally the formyl group is removed by alkaline hydrolysis to obtain compound (III) with a higher purity and yield. The total yield of three procedures is about 40%. Compound (III), an important intermediate, is alkylated at N4 with corresponding halide to obtain compound (IV). When using K2CO3/DMF, the reaction can take place at room temperature, and the yield is about 80%. If using K2CO3/CH3COCH3, NaHCO3/C2H5OH, or Et3N/CHCl3 as reaction systems, the reaction it needs reflux for about 8-24 h, and the color of the reaction mix will deepen as time passes. This will reduce the quality and yield of the products. Compounds IV-1 to IV-33 and IV-44 to IV-68 are obtained by the above mentioned procedures.
The goal compounds IV-34 to IV-43, IV-69 and IV-70 contain difunctional carbonyl and hydroxyl groups. N-benzyl piperazine is reacted with corresponding bromo-aralkyl ketones to obtain N1, N4-disubstituted compound (VI). Compound (VI) is reduced by KBH4 and then hydrogenated by 10% Pd—C at 70° C. in HAC to give compound (VIII). Reduction and hydrogenation of compound (VI) also can be carried out in one step through step h. But when the activity of carbonyl is weak, there are still many unreduced carbonyl materials left. Therefore, carbonyl group should be first reduced by KBH4 before hydrogenation in order to obtain compound (VIII) with sufficient purity.
The goal compounds IV-34 to IV-43, IV-69 and IV-70 can be obtained by using a key intermediate compound (VIII) with halogen-aralkyl ketones.
Halogenated aralkyl formyl alkyl compounds in steps b, d and f can be obtained commercially, but can also be prepared with bromine or copper bromide corresponding aralkyl ketones using methods known in the literature.
The inventors discovered that aralkyl formyl alkyl piperazine derivatives in the present invention are effective against ischemic cerebral apoplexy, and especially, they have therapeutic activities for acute ischemia cerebral infarction. Also, these compounds have neuroprotective activities after ischemic cerebral apoplexy. Therefore, the compounds from this invention can be used to develop acute therapeutic agents against ischemia cerebral infraction and a neuroprotective agent after ischemic cerebral apoplexy.
Using well-known methods in the art an effective amount of the compounds from this invention can be combined with any pharmaceutically acceptable carriers to prepare clinical solid formulations, such as tablets, powders, capsules or injections, etc.
The carriers mentioned above represent the routine pharmaceutical carriers, such as dilutents, excipents (water, etc), filling materials (starch, sugar, etc), adhesives (fibrin derivatives, gelatin, polyvinyl, pyrrolidone, etc), wetting agents (glycerin, etc), surface active agents (cetanol, etc), disintegrants (calcium carbonate, etc) and lubricants (talc powder, calcium stearate, magnesium stearate, etc).
According to claims of this invention, the content of the compound is about 0.1-99.5% in the tablet, powder, capsule or injection.
The inventive compounds can be taken by the patients in the form of oral administration, injection and so on. For oral administration, the compounds can be prepared into regular solid formulations, such as tablets, powders or capsules. For injection, they can be prepared into liquid form.
The dosage of these compounds could be regulated according to the age and the weight of the patients, and specific cases of diseases. Daily whole dosage can be 2-50 mg/kg (po) or 1-20 mg/kg (iv).
The compounds in this invention have showed potent prevention and therapeutic actions on global cerebral ischemia and focal cerebral ischemia on animals. Their therapeutic effects are much better than previously known related drugs.
The inventors also discovered that the inventive compounds have low toxicity levels and fewer side effects for the central nervous system.
A mixture of piperazine (258 g, 3 mol) and methyl formate (180 g, 3 mol) was refluxed for 8 h, the excessive piperazine was removed in vacuo, and collected at 130-134° C./8-10 mm-Hg 240 g of N-formyl piperazine was obtained (70%).
A mixture of the above product (310 mmol), aralkyl formylalkyl halogen (372 mmol), K2CO3 (465 mmol) and KI (30 mmol) in 320 ml of acetone was refluxed for 8-16 h, filtered off; the filtrate was evaporated in vacuo. 5% NaOH (350 ml) was added to the residue, after refluxed for 10 h, and then adjusted to a ph of 8 by 6 N HCl, extracted with CHCl3 (200 ml×3). The combined organic layer was washed with 50 ml of water and saline, dried (MgSO4), filtered and evaporated. The residue was dissolved in 20 ml of ethanol and then adjusted to a ph of 3 by HCl/C2H5OH (5N), the resulting precipitate was recrystallized from aqueous ethanol to obtain N-aralkyl formylalkyl piperazine dihydrochloride (III) (55-60%).
A mixture of compound (III)(10 mmol), aralkyl halogen (12 mmol), KI (1 mmol) and K2CO3 (35 mmol) in DMF (50 ml) was stirred at 25° C.-60° C. for 8-12 h, filtrated, and then evaporated to dryness, 50 ml of water and EtOAc (100 ml×3) were added to the residue, the organic layer was washed with saline, dried (MgSO4). Filtered and evaporated, the residue was dissolved by 30 ml of ethanol and then adjusted to a PH of 2 by HCl/C2H5OH (5N); the resulting precipitate was recrystallized from ethanol or CH3OH to obtain the title product (IV)(60-85%).
A mixture of piperazine (350 mmol), KOH (100 mmol) and hexadecyl-trimethyl ammonium bromide (CTAB, 1 mmol) in water (18 ml) was heated to get a solution. Thereafter, benzyl chloride (100 mmol) in 140 ml of benzene was added to the solution dropwise at 70° C., and refluxed for 1 h. The organic layer was washed with water and saline, dried (MgSO4), filtered and evaporated, the residue was dissolved by 50 ml of ethanol and adjusted to a PH of 2 by HCl/C2H5OH (5N), the resulting precipitate was recrystallized from ethanol to obtain N-benzyl piperazine dihydrochloride (55-86%).
A mixture of N-benzyl piperazine dihydrochloride (20 mmol), aryl formyl alkyl halide (24 mmol), K2CO3 (7 mmol) and KI (2 mmol) in 100 ml of acetone was treated according to the general preparation 2 to obtain compound (VI) (65-75%).
To a mixture of compound (VI) (3.5 mmol) and KHCO3 (8.75 mmol) in methanol (60 ml) was added KBH4 (14 mmol), stirred at room temperature for 2 h, and then at 50° C. for 1 h, adjusted to a PH of 3 by 1N aqueous NaOH and then filtered. The filtrate was extracted with EtOAC (40 ml×3), washed with saline, evaporated to dryness, which was dissolved in 20 ml of ethanol, and adjusted to a PH of 2 by HCl/C2H5OH (5N), the resulting precipitate was recrystallized from ethanol to obtain the title compound (60-80%).
To a mixture of the above compound (VII) in HAc (60 ml) was added 10% Pd—C (0.4 g), stirred with H2 at 70° C. for 4 h, filtered off and evaporated to dryness, which was dissolved in 10 ml of ethanol, and adjusted to a PH of 2 by HCl/C2H5OH (5N), the resulting precipitate was recrystallized from ethanol to obtain the title compound (80-85%).
A mixture of piperazine (2 g, 23.22 mmol), 2-chloro-1-phenylethanone (7.89 g) and K2CO3 (8 g, 58.08 mmol) in 30 ml of DMF was stirred at 50° C. for 8 h, and treated according to the general preparation 2 to give 6.6 g of compound (IV-2) (72%), mp 258-259° C., M+ 322.
Elemental analysis (found): C20H22N2O2.2HCl (C: 60.91%, H: 6.40%, N, 7.26%)
1HNMR (DMSO-d6): δ 3.46 (m, 8H, piperazine-H), 5.09 (s, 4H: 2COCH2N), 7.59-8.02 (m, 10H, ArH).
A mixture of N-formyl piperazine (20 g, 175 mmol), 2-chloro-1-phenylethanone (32.5 g, 210 mmol) and K2CO3 (36 g, 262 mmol) in 180 ml of acetone was treated according to the general preparation 1 to give N-phenacyl piperazine dihydrochloride, 28 g (57%), mp 246-8° C. (dec).
A mixture of 2-bromo-1-(naphthalen-2-yl)ethanone (0.95 g, 3.8 mmol), N-phenacyl piperazine dihydrochloride (0.89 g, 3.2 mmol) and K2CO3 (1.56 g, 11.2 mmol) in 30 ml of DMF was stirred at 50° C. for 10 h, and treated according to the general preparation 2 to give compound (IV-7), 0.88 g (60.69%), mp236-237° C., M+ 373.
Elemental analysis (found): C24H24N2O2.2HCl.1/2H2O.(C: 63.41%, H: 5.87%, N: 5.96%)
1HNMR (DMSO-d6/D2O): δ 3.56 (m, 8H, piperazine-H), 4.90 (s, 2H, PhCOCH2), 5.03 (s, 2H), 7.54-8.63 (m, 12H, ArH).
A mixture of 2-bromo-1-phenylpropan-1-one (3 mmol), N-phenacyl piperazine dihydrochloride (2.5 mmol) and K2CO3 (8.75 mmol) in 30 ml of DMF was treated according to the general preparation 2 to give compound (IV-8), 0.64 g (62%), mp 236-238° C., M+ 336.
Elemental analysis (found): C21H24N2O2.2HCl (C: 62.02%, H: 6.64%, N, 6.57%)
1HNMR (DMSO-d6): δ 1.73 (d, J=6.0, 3H, COCH(CH3)N), 3.56 (m, 8H, piperazine-H), 5.44 (m, br, 1H, COCHN), 4.90 (s, 2H, PhCOCH2), 7.55-8.05 (m, 10H, ArH).
A mixture of 2-chloro-1-(4-methoxyphenyl)ethanone (3 mmol), N-phenacyl piperazine dihydrochloride (3 mmol) and K2CO3 (10 mmol) in 30 ml of DMF was treated according to the general preparation 2 to give compound (IV-9), 0.68 g (62%), mp 226-228° C., M+ 352.
Elemental analysis (found): C21H24N2O3.2HCl.H2O (C: 57.13%, H: 6.10%, N, 6.23%)
1HNMR (DMSO-d6): δ 2.05 (s, 3H, CH3O), 3.56 (m, 8H, piperazine-H), 5.07-5.12 (m, 4H, COCH2N), 7.53-8.04 (m, 9H, ArH).
A mixture of piperazine (1.5 mmol), 2-bromo-1-phenylpropan-1-one (3 mmol), and K2CO3 (8.75 mmol) in 30 ml of DMF was stirred at 50° C. for 8 h, then was treated according to the general preparation 2 to give compound (IV-10), 0.55 g (85%), mp 240-242° C., M+ 350.
Elemental analysis (found): C22H26N2O2.2HCl.1/2H2O (C: 61.40%, H: 6.74%, N: 6.64%)
1HNMR (DMSO-d6): δ 1.73 (d, J=6.0, 6H: 2COCH(CH3)N), 3.56 (m, 8H, piperazine-H), 5.44 (m, br, 2H, COCHN), 7.53-8.06 (m, 10H, ArH).
A mixture of 2-chloro-1-(4-nitrophenyl)ethanone (3.2 mmol), N-phenacyl piperazine dihydrochloride (3 mmol), and K2CO3 (9 mmol) in 30 ml of DMF was treated according to the general preparation 2 to give compound (IV-11), 0.71 g (61%), mp 204-205° C., M+ 367.
Elemental analysis (found): C20H21N3O4.2HCl.3/2H2O (C: 51.71%, H: 5.80%, N: 8.99%)
1HNMR (DMSO-d6): δ 3.56 (m, 8H, piperazine-H), 5.09-5.21 (m, 4H: 2COCH2N), 7.55-9.05 (m, 9H, ArH).
A mixture of 3-bromo-1-phenylpropan-1-one (1.5 g, 8.9 mmol), N-phenacyl piperazine dihydrochloride (2.05 g, 7.4 mmol) and K2CO3 (21.75 mmol) in 30 ml of DMF was treated according to the general preparation 2 to give compound (IV-13), 0.64 g (76%), mp 204-205° C., M+ 336.
Elemental analysis (found): C21H24N2O2.2HCl (C: 61.17%, H: 6.37%, N, 6.48%)
1HNMR (DMSO-d6): δ 3.37-3.41 (m, 4H, NCH2CH2CO), 3.55 (m, 8H, piperazine-H), 5.15 (s, 2H, COCH2N), 7.43-7.95 (m, 10H, ArH).
A mixture of 2-bromo-1-phenylpropan-1-one (3 mmol), N-(2-hydroxy-phenyl acetyl) piperazine hydrochloride (2.5 mmol) and K2CO3 (8.75 mmol) in 30 ml of DMF was treated according to the general preparation 2 to give compound (IV-18), 0.65 g (67%), M+ 353.
Elemental analysis (found): C21H24N2O3.HCl (C: 64.80%, H: 6.42%, N, 7.20%)
1HNMR (DMSO-d6): δ 1.73 (d, J=6.0, 3H, COCH(CH3)N), 3.56 (m, 8H, piperazine-H), 4.77 (s, 1H, PhCHCO), 5.44 (m, br, 1H, COCHN), 7.55-8.05 (m, 10H, ArH).
A mixture of 2-bromo-1-(5-chloro-6-methoxynaphthalen-2-yl)propan-1-one (3.8 mmol), N-phenacyl piperazine dihydrochloride (0.89 g, 3.2 mmol) and K2CO3 (1.56 g, 11.2 mmol) in 30 ml of DMF are stirred at 50° C. for 10 h, then was treated according to the general preparation 2 to give compound (IV-19), 1.09 g (61%), M+ 451.
Elemental analysis (found): C26H27ClN2O3.2HCl.2H2O.
1HNMR (DMSO-d6/D2O): δ 1.70 (d, J=6.0, 3H, COCH(CH3)N), 3.56 (m, 8H, piperazine-H), 4.90 (s, 2H, PhCOCH2), 5.41 (m, br, 1H, COCHN), 8.64-9.11 (m, 4H, ArH).
A mixture of N-benzyl-2-chloroacetamide (3.9 mmol), trans-1-cinnamylpiperazine dihydrochloride (5.1 mmol, prepared by using the general preparation 1) and K2CO3 (8.5 mmol) in 30 ml of DMF was treated according to the general preparation 2 to give compound (IV-21), 0.75 g (69%), mp 226-228° C., M+ 349.
Elemental analysis (found): C22H27N3O.2HCl.H2O (C: 59.97% H: 7.02% N, 9.65%)
1HNMR (DMSO-d6): δ 3.46-3.57 (m, 10H, piperazine-H), 3.87-3.98 (m, 2H, CH═CH) 4.37 (m, 2H, NCH2CH═CH), 6.24 (t, 1H, NHCO), 6.90 (t, 2H, PhCH2NH), 7.27-7.48 (m, 10H, ArH).
IR (KBr): v3310, 3070, 2380, 1660, 1595, 1450, 1280, 1000, 980, 950, 745, 690.
A mixture of 2,4-difluorobenzylsulfonylchloride (3.5 mmol), N-phenacyl piperazine dihydrochloride (3 mmol), and K2CO3 (10.5 mmol) in 30 ml of DMF was treated according to the general preparation 2 to give compound (IV-22), 0.81 g (71%), M+ 412.
Elemental analysis (found): C19H20F2N2O3S.HCl.3/2H2O (C: 57.21%, H: 5.89%, N: 7.10%)
1HNMR (DMSO-d6): δ 3.56 (m, 8H, piperazine-H), 4.89 (s, 2H, ClSO2CH2), 5.09 (s, 2H, COCH2N), 7.24-8.05 (m, 8H, ArH).
This compound has the formula as defined in claim 1, wherein Ar1 and Ar2 represent phenyl respectively; R1, R2, and R3, each represents hydrogen;
A mixture of N-phenacyl piperazine dihydrochloride (1 g, 3.6 mmol), chloroacetyl-benzylamine (0.73 g, 4 mmol, prepared by chloroacetylchloride and benzylamine in 2N aqueous NaOH), KI (10 mg) and K2CO3 (1.8 g, 13 mmol) in 30 ml of DMF was stirred at 50° C. for 8 h, then filtered, and evaporated off the solvent, the residue was extracted with 20 ml of water and EtOAC (50 ml×3). Combined organic layer was washed with water and saline, dried (MgSO4), filtered and evaporated. The residue was dissolved by 10 ml of ethanol and then adjusted to a PH of 2 by HCl/C2H5OH (5N), the resulting precipitate was recrystallized from aqueous ethanol or methanol to obtain compound (IV-23), 0.84 g (55%), mp208-210° C., M+ 351.
Elemental analysis: C21H25N3O2.2HCl. Found (wt %): C 59.40H 6.45 N9.87; Theoretical (wt %): C 59.55H 6.43 N 9.93.
IR (KBr): v 3180, 2950, 1690, 1670, 1570 cm−1.
1HNMR (DMSO-d6): δ 3.35-3.46 (m, 8H, piperazine-H), 3.89 (s, 2H, PhCH2), 4.32 (s, 2H, NCH2CON), 4.88 (s, 2H, COCH2N), 7.23-7.96 (m, 10H, ArH), 9.13 (s, NH).
Purity (HPLC): >99%
A mixture of chloroacetylbenzylamine (3.06 mmol), N-[2-(benzylamino)-2-oxo-ethyl]piperazine dihydrochloride (3 mmol, prepared by using the general preparation 1) and K2CO3 (10.5 mmol) in 30 ml of DMF was treated according to the general preparation 2 to give compound (IV-26), 0.91 g (80%), M+ 365.
Elemental analysis (found): C22H25N3.2HCl.H2O
1HNMR (DMSO-d6): δ 1.74 (d, J=6.0, 3H, COCH(CH3)N), 3.56 (m, 8H, piperazine-H), 4.14 (s, 2H, PhCH2), 4.35 (s, 2H, NCH2CON), 5.44 (m, br, 1H, COCHN), 7.23-8.03 (m, 10H, ArH)
A mixture of chloroacetylbenzylamine (3.06 mmol), N-(4-methoxyphenacyl) piperazine dihydrochloride (3 mmol, prepared by using the general preparation 1) and K2CO3 (10.5 mmol) in 30 ml of DMF was treated according to the general preparation 2 to give compound (IV-28), 0.86 g (74%), M+ 381.
Elemental analysis: C22H27N3O3.2HCl 1/2H2O
1HNMR (DMSO-d6): δ 3.56 (m, 8H, piperazine-H), 3.77 (s, 3H, CH3O), 4.14 (s, 2H, PhCH2), 4.35 (s, 2H, NCH2CON), 5.09 (s, 2H, COCH2N), 7.26-8.03 (m, 9H, ArH).
A mixture of (R)-2-chloro-N-(1-phenylethyl)acetamide (3 mmol), N-phenacyl piperazine dihydrochloride (2.5 mmol) and K2CO3 (8.75 mmol) in 30 ml of DMF was treated according to the general preparation 2 to give compound (IV-29), 0.72 g (63.2%), M+ 365.
Elemental analysis: C22H27N3O2.2HCl.H2O
1HNMR (DMSO-d6): δ 1.44 (d, 3H, NHCHCH3), 3.55 (m, 8H, piperazine-H), 4.04 (s, 1H, PhCHCH3), 4.35 (s, 2H, NCH2CON), 5.12 (s, 2H, COCH2N), 7.23-8.14 (m, 10H, ArH).
A mixture of N-(4-methoxybenzyl)-2-chloroacetamide (3.65 mmol), N-phenacyl piperazine dihydrochloride (3.97 mmol) and K2CO3 (10.5 mmol) in 30 ml of DMF was treated according to the general preparation 2 to give compound (IV-30)(61%), M+ 381.
Elemental analysis: C22H27N3O3 .2HCl 1/2H2O
1HNMR (DMSO-d6): δ 3.55 (m, 8H, piperazine-H), 3.77 (s, 3H, CH3O), 4.14 (s, 2H, PhCH2N), 4.35 (s, 2H, NCH2CON), 5.12 (s, 2H, COCH2N), 7.23-8.14 (m, 9H, ArH).
A mixture of 2-chloro-N-(pyridin-2-ylmethyl)acetamide (1.3 mmol), N-phenacyl piperazine dihydrochloride (1 mmol), and K2CO3 (8.75 mmol) in 30 ml of DMF was treated according to the general preparation 2 to give compound (IV-31), 0.7 g (60.45%), M+ 381.
Elemental analysis: C20H24N4O2.3HCl
1HNMR (DMSO-d6): δ 3.33-3.54 (m, 8H, piperazine-H), 4.33 (s, 2H, NHCH2), 4.39 (s, 2H, NCH2CON), 5.12 (s, 2H, COCH2N), 7.46-8.96 (m, 9H, ArH, pyridine-H).
A mixture of N-[1-(3,4-methylenedioxyphenyl)methyl]-2-chloroacetamide (5 mmol), N-phenacyl piperazine dihydrochloride (5 mmol) and K2CO3 (17.5 mmol) in 60 ml of acetone was treated according to the general preparation 2 to give compound (IV-32), 0.76 g (63.45%), M+ 395.
Elemental analysis: C21H25N2O3 .2HCl 1/2H2O
1HNMR (DMSO-d6): δ 2.42 (s, 2H, OCH2O), 3.33-3.54 (m, 8H, piperazine-H), 4.33 (s, 2H, NH CH2), 4.39 (s, 2H, NCH2CON), 5.12 (s, 2H, COCH2N), 7.25-8.11 (m, 8H, ArH).
A mixture of chloroacetylbenzylamine (0.43 g, 2.3 mmol), N-[1-(5-chloro-6-methoxy-2-naphthoyl)ethyl] piperazine dihydrochloride (0.8 g, 1.9 mmol, prepared by using the general preparation 1) and K2CO3 (0.95 g, 6.6 mmol) in 40 ml of acetone was treated according to the general preparation 2 to give compound (IV-33), 0.86 g (60%), M+ 480.
Elemental analysis (found): C27H30ClN3.2HCl.H2O (C: 57.21%, H: 5.89%, N, 7.10%)
1HNMR (DMSO-d6): δ 1.68 (s, 3 h, CH3CH), 3.64-4.02 (br, 11H, piperazine-H), 4.40 (s, 3H, OCH3), 5.37 (t, 2H, PhCH2), 7.24-7.70 (m, 10H, ArH), 8.34 (m, 1H, NH).
A mixture of N-benzyl-piperazine dihydrochloride (20 mmol, prepared by using the general preparation 3, yield 70%), 2-chloro-1-phenylethanone (24 mmol), K2CO3 (70 mmol) and KI (2 mmol) in 100 ml of acetone was treated according to the general preparation 2 to give N1-benzyl-N4-phenacyl piperazine dihydrochloride (67%).
The above product (3.5 mmol) in 60 ml of methanol was treated according to the general preparation 4 to give N1-benzyl-N-4-(phenylethyl-2-ol) piperazine dihydro-chloride (65%).
N1-benzyl-N4-(phenylethyl-2-ol) piperazine dihydrochloride (2.28 mmol) was treated according to the general preparation 5 to give N-(phenylethyl-2-ol) piperazine dihydrochloride (1.94 mmol) (85%), which was treated with benzoyl chloride (2.33 mmol) and K2CO3 (6.8 mmol) in 10 ml of DMF according to the general preparation 2 to give compound (IV-34), 0.51 g (76.4%), mp 116-118° C., M+ 311.
Elemental analysis (found): C19H22N2O2.HCl
1HNMR (DMSO-d6): δ 3.27-3.65 (m, 10H, NCH2, piperazine-H), 5.21 (m, 1H, CHOH), 7.27-7.47 (m, 10H, ArH).
IR (KCl): v3300, 2940, 1625, 1490, 1100 cm−1.
A mixture of N-(2-phenylethyl-2-ol) piperazine dihydrochloride (3 mmol, prepared in the similar procedure of example 20), 2-bromo-1-phenylethanone (3.6 mmol) and K2CO3 (10.5 mmol) in 15 ml of DMF was treated according to the general preparation 2 to give compound (IV-36), 0.81 g (67.2%), mp 220-221° C., M+ 325.
Elemental analysis (found): C20H24N2O2 .2HCl 1/2H20
IR (KCl): v3300, 2970, 1690, 1620, 1590, 1060 cm−1
A mixture of N-(2-phenylethyl-2-ol) piperazine dihydrochloride (2 mmol), N-benzyl-2-chloroacetamide (2.4 mmol), and K2CO3 (7 mmol) in 10 ml of DMF was treated according to the general preparation 2 to give compound (IV-37), 0.64 g (75.1%), mp 206-208° C., M+ 354.
Elemental analysis (found): C21H27N3O2.2HCl
IR (KCl): v 3350, 3220, 2980, 1680, 1600, 1540 cm−1
A mixture of N-benzyl-piperazine dihydrochloride (2 mmol), 3-bromo-1-phenylpropan-1-one (36 mmol), K2CO3 (105 mmol) and KI (3 mmol) in 150 ml of acetone was treated according to the general preparation 2 to give N1-benzyl-N4-(3-oxo-3-phenylpropyl)-piperazine dihydrochloride (22 mmol)(73.2%).
A mixture of the above product (3.5 mmol) in 60 ml of methanol was treated according to the general preparation 4 to give N1-benzyl-N4-[(3-hydroxy-3-phenyl)propyl] piperazine dihydrochloride (2.6 mmol)(75%), which was treated according to the general preparation 5 to give N-[(3-hydroxy-3-phenyl)propyl] piperazine dihydrochloride (2.07 mmol)(83%).
The above product (2 mmol) was treated with 2-chloro-1-(4-methoxyphenyl)ethanone (2.4 mmol) and K2CO3 (7 mmol) in 10 ml of DMF according to the general preparation 2 to give compound (IV-38), 0.62 g (70.4%), mp 240-243° C., M+ 368.
Elemental analysis (found): C22H28N2O3.2HCl (C: 60.21%, H: 7.03%, N, 6.31%)
A mixture of N-(2-phenylethyl-2-ol) piperazine dihydrochloride (2 mmol), 2-bromo-1-(4-chlorophenyl)ethanone (2.4 mmol) and K2CO3 (7 mmol) in 10 ml of DMF was treated according to the general preparation 2 to give compound (WV-39), 0.63 g (70%), M+ 359.
Elemental analysis (found): C20H23ClN2O2.2HCl.H2O
IR (KCl): v3300, 2960, 1700, 1620, 1570, 1060 cm−1
A mixture of N-(2-phenylethyl-2-ol) piperazine dihydrochloride (2 mmol), 2-bromo-1-(4-methoxyphenyl)ethanone (2.4 mmol) and K2CO3 (7 mmol) in 10 ml of DMF was treated according to the general preparation 2 to give compound (IV-40), 0.66 g (71%), M+ 354.
Elemental analysis (found): C21H26N2O3.2HCl.2H2O
IR (KCl): v3300, 2950, 1690, 1625, 1550, 1060 cm−1
A mixture of N-(2-phenylethyl-2-ol) piperazine dihydrochloride (2 mmol), 2-bromo-1-phenylethanone (2.4 mmol) and K2CO3 (7 mmol) in 10 ml of DMF was treated according to the general preparation 2 to give compound (IV-41), 0.52 g (63%), M+ 338.
Elemental analysis (found): C21H26N2O2 .2HCl
IR (KCl): v3300, 2870, 1750, 1610, 1590, 1030 cm−1
According to the literature (Luzzi, Br J Pharmacol, 95: 1271, 1988), maximum contraction of isolated longitudinal ileomuscle preparations of guinea pig induced by L-Glu, were used to examine the activities of the compounds on the NMDA receptor.
Methods: L-Glu was used to induce the contraction of the isolated muscle preparations, Ketamine (the antagonist of NMDA receptor ion channel) and Ifenprodil (the antagonist of NMDA receptor polyamine site) were used as the positive control. 13 compounds were tested, the results indicate that 8 compounds could inhibit from the maximum contraction induced by Glu, showed the antagonistic activities on NMDA receptor (10−5M); 5 compounds (IV-1, 9, 10, 11, 35) could excite preparations directly and induce preparations contraction, showed Glu-like excited action. The results were showed on Table 2.
*represents the restrain rate of compound (10−5M) inducing the contraction of preparations
With the mice models of anoxia induced by sodium nitrite (225 mg/kg, ip), the rate of the prolonging the survival duration of the mice was observed to evaluate the compound's activities of against anoxia. Of the 40 compounds (20 mg/kg sc) in this invention screened, the result showed that these compounds could prolong to various degrees the survival duration of the mice. The rates of the prolongation of 9 compounds (IV-2, 10, 23, 32, 34, 36, 39, 40, 41) were more than 50%, which indicated the effect of anti-cerebral anoxia. IV-23 and IV-2 prolonged the survival duration by 100% of the animals, showing remarkably protective action for cerebral anoxia. (Table 3)
The animal models of the bilateral common carotid artery occlusion with exsanguine hypotension in the rats were used to investigate the effect against global cerebral ischemia.
Methods: The animals were administrated four compounds (IV-2, 23, 34, 36) orally for 3 days before the experiment. One hour after administration (20 mg/kg, 5 ml/kg), (saline (5 ml/kg) as vehicle group and Nimodipine (1 mg/kg) as positive control), the EEG recovery time of the rats on reperfusion after 10 min occlusion was observed to evaluate the effect of compounds on anti-cerebral ischemia. The results of the 4 compounds were shown on Table 4.
The results indicate that compared with the saline group, 3 compounds (IV-23, IV-34 and IV-2) significantly shortened the recovery time of EEG after cerebral ischemia in rats. These results suggested that the compounds could protect brain from damage induced by ischemia-reperfusion. The activities of IV-23 and IV-34 were comparable with Nimodipine.
The focal ischemia rat model by occlusion of middle cerebral artery (MCA) was used to determine the protective effects of the compounds on focal cerebral ischemia. The infarct size after focal cerebral ischemia and the weight percentage of cerebral hemisphere were calculated to evaluate the compounds' effects on focal cerebral ischemia. The results of the two compounds (IV-20, 21, 22, 23, 33) are shown on Table 5.
*P > 0.05,
**P < 0.01 compared with saline group
Percentage of infarct volume: IV-23, IV-33 and IV-22 (20 mg/kg, ig) decreased the infarct region weight and percentage of infarct region weight to right hemisphere weight significantly (p<0.01); The Nimodipine group (20 mg/kg) showed no difference compared with the saline group (p=0.072).
Neurological deficit score: IV-23 decreased the rat Neurological deficit scores significantly, stronger than Nimodipine, 24 hours after operation. The results showed that compound IV-23 has a better protective effect on focal cerebral ischemia induced by occluded middle cerebral artery than others.
1. The Preclinical Pharmacodynamic Results of IV-23 in Animals
(1) The Anti-Anoxia Effects of IV-23 in Mice
a. Anoxia Caused by Sodium Nitrite
One model was established to test the time needed for mice to die because of anoxia caused by sodium nitrite (225 mg/kg, ip). IV-23 (20 mg/kg, sc) can prolong the time for 100%, indicating significant anti-cerebral anoxic anoxia activity.
b. Anoxic Anoxia Experiment
Methods: Male Kunming mice were divided into 8 groups, 12 mice for each group. One group is injected subcutaneously with saline (0.2 mg/10 g, sc), other groups with ACEA1021 (NMDA receptor antagonist under clinical trial) or IV-23. 30 minutes after administration, the animals were put separately into wide-mouth bottles with soda lime, which more quickly closed. The survival time for each mice was recorded, and the group average of survival time was calculated and compared with the saline group.
Experimental results: The average survival time of the saline group was 14.05±0.65 minutes; The survival time of the IV-23 and ACEA-1021 groups was significantly longer in comparison (Table 6). ED50 for IV-23 and ACEA-1021 were 6.2 mg/kg and 29.2 mg/kg, respectively, suggesting a protective effect of IV-23 for cerebral anoxia.
Note:
Compared with saline: *p < 0.05, **p < 0.01
(2) Protection of IV-23 Against Global Cerebral Ischemia in Rats
The effect of IV-23 on cerebral ischemia-reperfusion in rats was studied using four arteries reversible occlusion by measuring the recovering time of the electroencephalogram and the righting reflex (a short time indicates a strong effect). IV-23 (5 mg/kg, 10 mg/kg, 20 mg/kg, ip, respectively) shortened obviously the recovering time and the righting reflex time compared with the saline group and the Nimodipine group (1 mg/kg, p<0.01), indicating that IV-23 has protection on global cerebral ischemia-reperfusion injury in rats.
Δ P > 0.05, ΔΔ P < 0.05, ΔΔΔ P < 0.01 compared with a saline group
*P > 0.05, **P < 0.05, ***P < 0.01 compared with a Nimodipine group
(3) Protection of IV-23 on Focal Cerebral Ischemia in Rats.
a. The Focal Cerebral-Infarction of Using Electrical Coagulation to Occlude MCA:
The percentage for necrosis: compared with the vehicle control group, 10 mg/kg and 20 mg/kg of IV-23 significantly decreased the infarct size and the ratio between infarct size and the right cerebral hemisphere (p<0.01). For the 5 mg/kg group, the percentage of the rat's infarct size was decreased, but the difference is not significant (p=0.098). The effect is not significant for the Nimodipine mg/kg. The behavioral score of 24 hours after the operation: the score of the middle-dose and the high-dose groups were significantly decreased, the difference for middle-dose group was significantly (p<0.01) better than the group of Nimodipine. The results show that IV-23 has a great theraputic effect on the focal cerebral-infarction caused by ligation of MCA (Table 8), the effect is dose-related.
*P > 0.05,
**P < 0.05,
***P < 0.01 compared with negative criteria
a. Focal brain injury caused by photochemical induction of occlusion of the artery:
Compared with the vehicle (saline), IV-23 can significantly improve the rat's neurological deficit (p<0.05), decrease the weight of infarct area, the percent by weight of infarct area, per the right cerebra hemisphere (p<0.01). The percentage of infarction was lowered by 52% at 24 hours after operation. Compared with ACEA-1021, IV-23 can significantly reduce the neurological deficit score and the percentage of infarct area (p<0.01) (See Tab 9).
*P > 0.05,
**P < 0.05,
***P < 0.01 compared with vehicle.
ΔP>0.05,
ΔΔP<0.05,
ΔΔΔP < 0.01 compared with positive control.
b. Temporary occlusion of the right MCA in rats caused by suture. The results show that ACEA-1021 can significantly reduce the ratio of volume after being under ischemia for 6 hours. Different doses of IV-23 can reduce the percent of volume of infarction significantly, and it is related with time of ischemia (Table 10). After 6 hours of ischemia, 5 mg/kg will significantly reduce the volume of the cerebral infarction; after 3 hours of ischemia, 5 mg/kg can reduce the volume by 46.3% (Table 11).
acompared with saline for 1 hr
bcompared with saline for 3 hr
ccompared with saline for 6 hr
*
The three models of focal cerebral ischemia showed that IV-23 reduces the volume of cerebral ischemic significantly, it has clear protective and therapeutic effects, and the effect is much better than that of Nimodipine and ACEA-1021.
1. Effects on the Hippocampal Neuron of Newborn Rats:
Electro-physiological Analysis: When tested using the whole-cell patch clamp technique with rapidly isolated rat CA1 pyramidal neuron, IV-23 inhibited the electric current induced by NMDA (100 μm), and the inhibitive effect showed dose dependency. IC50: 562.7±1.1 μm (n=4, Hill coefficient 1.17), demonstrating that IV-23 inhibits the depolarization of the neuronal cell induced by NMDA, confirming that IV-23 is an antagonist of the NMDA receptor (See
Methods: The whole-cell patch-clamp technique. Separate the rat's hippocampi, slash the brain piece into 500 μm thick. Get the CA1 area of hippocampi, put it into artificial cerebral spinal fluid (ACSF) to incubate for more than 1 hour. Then the solution is oxygen saturated. After the incubation of the brain piece, put it into ACSF with protease XIII (1 mg/ml) for 5 minutes. Using trypsin inhibitor type II-S (3 mg/ml) to terminate the protease digestion, and then using test tube to break the brain piece to obtain free cells, let it stand for a while and then start the experiment.
The electro-physiological experiment used the technique of whole-cell patch-clamp. The amplifier in the experiment is Axon-200A patch-clamp amplifier, with the DigiData-1200A as a sampling port. The software used is AxoScope Version 1.0. The experiment uses as a standard the electric current generated by the whole-cell. The effect of various samples on the electric current was observed. IC50 was determined by proportion of different concentrations to the electric current of NMDA.
Results: IV-23 inhibits the electric current induced by NMDA in a concentration dependant way. IC50 is 562.7±1.1 μm (n=4), the Hill Coefficient is 1.17, indicating IV-23's inhibition to the depolarization of the neuronal cells.
2. IV-23 Reduces Injury to Neuronal Cells Caused By NMDA:
Primary culture of rat cerebral cortical neuronal cells were used. The results showed that IV-23 significantly reduced the increase of LDH specific activity caused by NMDA in the supernatant of primary culture of neuronal cell (Table 12), indicating that IV-23 has a protective effect on the injury (Table 13). This is further evidence that IV-23 is a new NMDA receptor antagonist, and has anti-cerebral ischemic injury functions as well.
**P < 0.01, compared with normal
*P < 0.05, **P < 0.01, compared with normal saline group.
3. Acute Toxicity of IV-23
LD50 (mice, mg/kg, 95% confidence limit) of i.v. and p.o. are 132.77(115.79-147.86) mg/kg and 855.73(737.87-970.70) mg/kg, respectively.
4. The Genotoxicity of IV-23
The Ames test of IV-23 was negative.
The rodent microkernel experiment of IV-23 was negative.
The chromosome aberration trial in mammalian cultural cell was negative.
5. The Antiplatelet Agglutination of IV-23
At a concentration of 1×10−4M, IV-23 did inhibit rats platelet aggregation induced by ADP, which suggested that its anti-cerebral infarction activities are not by the way of anticoagulation.
6. Conclusions:
IV-23 is a novel antagonist of NMDA receptor. It has an obvious effect on protecting the rats' primary culture nerve cell from the damage induced by NMDA. For focal cerebral infarction induced by rats' cerebral arterial ligation, oral administration (10 mg/kg) and injection (2.5 mg/kg) have evident therapeutic effects. IV-23's therapeutic action is better than Nimodipine and positive control ACEC-1021. IV-23 has a protective action against the global cerebral ischemia reperfusion damage. The induced mutation experiment is negative. IV-23 has shown obvious activity and safety on the models of rats' global and focal cerebral ischemia, indicating that it has preventive and therapeutic applications for human cerebral infraction.
| Number | Date | Country | Kind |
|---|---|---|---|
| 02111614.8 | May 2002 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN03/00273 | 4/16/2003 | WO |
