Design, synthesis and evaluation of some new 4-aminopyridine derivatives in learning and memory

Article abstract of DOI:10.1016/j.bmcl.2013.03.026

Some new anilide and imide derivatives of 4-aminopyridine (4AP) were synthesized and evaluated against antiamnesic, cognition enhancing and anticholinesterase activity through their respective in vitro and in vivo models. These newly synthesized derivatives have illustrated an enhanced cognition effect on elevated plus maze model and also demonstrated a significant reversal in scopolamine-induced amnesia in same model. The IC₅₀ value of synthesized compounds showed maximum activity of 4APMb compared to standard drug donepezil and other derivatives, whereas its enzyme kinetic study revealed a non-competitive inhibition of acetycholinesterase (AChE) and a competetive inhibition of butyrylcholinesterase (BChE). Significant inhibitions in AChE activity by all the synthesized compounds were found in specific brain regions that is prefrontal cortex, hippocampus and hypothalamus. The docking study confirmed their consensual interaction with AChE, showed an affinity and binding with the key peripheral anionic site residues Trp-286, Tyr-124 and Tyr-341 of AChE.

Full text of DOI:10.1016/j.bmcl.2013.03.026

Bioorganic & Medicinal Chemistry Letters 23 (2013) 2984–2989
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Design, synthesis and evaluation of some new 4-aminopyridine
derivatives in learning and memory
⇑
Saurabh K. Sinha, Sushant K. Shrivastava
Pharmaceutical Chemistry Research Laboratory, Department of Pharmaceutics, Indian Institute of Technology, Banaras Hindu University, Varanasi, UP 221005, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Some new anilide and imide derivatives of 4-aminopyridine (4AP) were synthesized and evaluated
against antiamnesic, cognition enhancing and anticholinesterase activity through their respective
in vitro and in vivo models. These newly synthesized derivatives have illustrated an enhanced cognition
effect on elevated plus maze model and also demonstrated a significant reversal in scopolamine-induced
amnesia in same model. The IC50 value of synthesized compounds showed maximum activity of 4APMb
compared to standard drug donepezil and other derivatives, whereas its enzyme kinetic study revealed a
non-competitive inhibition of acetycholinesterase (AChE) and a competetive inhibition of butyrylcholin-
esterase (BChE). Significant inhibitions in AChE activity by all the synthesized compounds were found in
specific brain regions that is prefrontal cortex, hippocampus and hypothalamus. The docking study con-
firmed their consensual interaction with AChE, showed an affinity and binding with the key peripheral
anionic site residues Trp-286, Tyr-124 and Tyr-341 of AChE.
Received 1 October 2012
Revised 21 February 2013
Accepted 8 March 2013
Available online 16 March 2013
Keywords:
4
-Aminopyridine
Nootropic
Antiamnesic
Anticholinesterase
Elevated plus maze
Ó 2013 Elsevier Ltd. All rights reserved.
Progressive impairment in memory, cognitive functions and
behavioral disturbance has always been a major area of concern
for complex neurodegenerative disorders of the central nervous
system such as Alzheimer’s disease (AD).1 Patients suffering with
AD have low level of acetylcholine (ACh) and biosynthetic enzyme
choline acetyltransferase (ChAT) in the cortex and hippocampus.2
,3
2
Scheme 1. The synthetic pathway of the compounds here presented. Reagents and conditions: (a) THF, 25 °C, 3 h; (b) Ac O, AcONa, 80 °C 5 h.
⇑
Corresponding author. Tel.: +91 9452156527; fax: +91 5422368428.
E-mail addresses: sksinha.rs.phe@itbhu.ac.in, skshrivastava.phe@itbhu.ac.in
(
S.K. Shrivastava).
0
960-894X/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmcl.2013.03.026

S. K. Sinha, S. K. Shrivastava / Bioorg. Med. Chem. Lett. 23 (2013) 2984–2989
2985
Table 1
Concentration of synthesized derivatives and donepezil required for 50% inhibition of
AChE and BChE
Compound
IC50
(
lM) ± SEM
Selectivity for AChEa
AChE
BChE
4
4
4
4
APSa
APSb
APMa
APMb
40.33 ± 0.88
0.49 ± 0.02
48.67 ± 1.20
0.03 ± 0.014
0.04 ± 0.012
56.45 ± 0.60
1.39
7.79
13.49
367
3.82 ± 0.83
656.85 ± 1.60
11.02 ± 0.76
15.24 ± 0.88
Donepezil
381
a
Selectivity for AChE is defined as IC50 (BChE)/IC50 (AChE).
Figure 2. Effect of synthesized derivatives and donepezil (5 and 10 mg/kg) on
acetylcholinesterase (AchE) activity on different region of rat brain [A] prefrontal
cortex [B] hippocampus [C] hypothalamus. Results are expressed as mean ± SEM
Figure 1. Effect of synthesized derivatives and Donepezil on learning impairment
on elevated plus maze in wistar rats [A] at dose (5 mg/kg), [B] at dose (10 mg/kg).
(n = 6).
These parameters have a vital role in learning and memory there-
fore, in order to treat this specific disease it is necessary to improve
cholinergic neurotransmission which may be achieved by prevent-
ing the biotransformation of acetylcholine into the inactive metab-
olites choline and acetate at the specific sites of brain.4 Based on
this approach some drugs have been established and used to treat
Table 2
Reverse effect of synthesized derivative on scopolamine-induced amnesia on elevated
plus maze in rats
Treatment [dose (mg/kg)]
Transfer latency (s)
5
,6
the AD. The utility of 4AP derivatives in treating various neuro-
muscular disorders such as multiple sclerosis, botulism, spinal cord
injury, Alzheimer’s disease and myasthenia gravis have already
Day 1
Day 2
VEHICLE
SCP (1.0)
67.67 ± 0.88
86.83 ± 0.90
77.67 ± 0.76
74.83 ± 0.60
66.83 ± 0.60
65.50 ± 0.76
80.50 ± 0.76
77.67 ± 0.66
64.67 ± 0.84
61.33 ± 0.61
65.33 ± 0.66
62.50 ± 0.76
62.50 ± 0.76
81.50 ± 0.76
71.67 ± 0.66
a
7
,8
b
been reported in previous investigations which may be attrib-
uted to its capacity to penetrate the blood–brain barrier9 but the
therapeutic applications of the most common 4AP derivatives such
4
4
4
4
4
4
4
4
APSa (5.0) + SCP (1.0)
APSa (10.0) + SCP
APSb (5.0) + SCP
APSb (10.0) + SCP
APMa (5.0) + SCP
APMa (10.0) + SCP
APMb (5.0) + SCP
APMb (10.0) + SCP
70.00 ± 0.57b
60.67 ± 0.66b
58.33 ± 0.88
b
10
11
as tacrine and velnacrine have been restricted due to their high
toxicity. Another tacrine derivative amiridine is now under Phase
b
75.33 ± 0.80
72.50 ± 0.76b
1
2
b
III study in Japan.
56.33 ± 0.88
b
53.83 ± 0.60
Donepezil (5.0) + SCP
Donepezil (10.0) + SCP
56.67 ± 0.66b
54.50 ± 0.76b
NH
2
OH NH
2
NH
2
Data are expressed as mean ± SEM (n = 6). Data were statistically analyzed by one
way ANOVA.
N
N
a
N
Significantally different from control (vehicle treated) group p <0.001.
b
Tacrine
Velnacrine
Amiridine
Significantally different from scopolamine treated group p <0.001.

2
986
S. K. Sinha, S. K. Shrivastava / Bioorg. Med. Chem. Lett. 23 (2013) 2984–2989
Several carbamate derivatives of 4AP and Schiff bases of styryl-
pyridine have been synthesized and evaluated for their anticholin-
determined by adopting Ellman method.21 The results showed a
comparable activity and selectivity of 4APMb (0.03 ± 0.014 M),
(367) was observed with reference standard donepezil
(0.04 ± 0.012 M), (381) for AChE inhibition respectively (Table 1).
l
1
3,14
esterase activity.
This activity has also been evaluated in some
amides and imides derivatives of m-aminobenzoic acid and p-ami-
l
1
5,16
22
nobenzoic acid.
Some 4-aminobutyric acid (GABA) and 2-ind-
Further, enzyme kinetics study was also perform for the most ac-
olinone derivatives of 4-Aminopyridine have been reported to
possess antiamnesic activity.17 Docking study of different AChE
inhibitors revealed that the amino acid residues Tyr-72, Tyr-124,
Glu-285, Trp-286, and Tyr-341 constitute the peripheral anionic
site (PAS) in human acetylcholinesterase enzyme (hAChE). Binding
of ligands with these residues may be the key to the allosteric
modulation of hAChE catalytic activity.18 In our previous study,
some Schiff bases of 4-aminopyridine have been reported as cogni-
tion enhancing, antiamnesic and anticholinesterase activity. In
view of these facts we have designed and synthesized some new
anilide and imide derivatives of 4AP and evaluated for the same
activity as discussed earlier.
tive compound 4APMb, which demonstrated a non-competitive
inhibition of AChE (K
i
= 0.042 ± 0.016) and competitive inhibition
of BChE (K = 15.64 ± 0.66) enzymes. The non-competitive inhibi-
i
2
3
tion suggested a possible interaction of compound with the
peripheral anionic site (PAS) of AChE and was also confirmed by
docking studies. The synthesized compounds were then evaluated
for antiamnesic and cognition enhancing property in rat elevated
2
4
plus maze (EPM) model which is a simple method for evaluation
of learning and memory that depends upon measuring the transfer
latency of rats. A natural revulsion in rats to open and high spaces
have been observed, where in these types of studies animals usu-
ally spend more time in enclosed arms rather than open arms in
1
9
2
5
The reaction carried out of 4AP with succinic anhydride as well
as 4AP with maleic anhydride in tetrahydrofurane at room temper-
ature resulted the respective 4APSa and 4APMa compounds. These
derivatives were transformed into 4APSb and 4APMb, by heating it
in acetic anhydride with an equimolecular amount of sodium ace-
plus maze test. This suggests a reduced transfer latency, where
animals moves from the open arms to the enclosed arms that de-
pends on previous experience of rats entering the open arm which
may be attributed to an enhanced memory. Pre-treatment with
tested compounds resulted in reduced transfer latency as com-
pared to control group on first and second day of EPM exposure
in significant and dose dependant manner, indicating facilitated
learning process (Fig. 1). The scopolamine (1 mg/kg) significantly
increased transfer latency as compared to control group [p
<0.001], resulting in amnesia which was reversed by tested com-
2
0
tate (Scheme 1). The reaction was monitored by TLC and forma-
tion of these compounds was confirmed by clear observation of
1
shifting of value of –NH
2
group of 4AP in IR and H NMR. In IR dou-
À1
À1
blet values of 3456 and 3395 cm shifted to 3369 cm (4APSa
and 4APMa) which disappeared in case of compounds 4APSb and
1
26
4
9
APMb. Likewise in H NMR 4.5 d ppm shifted to downfield 8.9 and
.3 d ppm for 4APSa and 4APMa while a total disappearance of the
pounds and donepezil significantly [p <0.001] (Table 2). The three
specific brain regions that are involved in processing of memory
and high innervations of cholinergic neurons include prefrontal
cortex, hippocampus and hypothalamus. It is reported that 50–
90% reduction in ChAT, an enzyme which synthesizes acetylcholine
peak was observed in 4APSb and 4APMb.
The 50% inhibitory concentration (IC50) of all the derivatives on
acetycholinesterase (AChE) and butyrylcholinesterase (BChE) was
Figure 3. Hydrophobic interactions: 4AP ring of 4APMb are well placed in the hydrophobic pockets.

S. K. Sinha, S. K. Shrivastava / Bioorg. Med. Chem. Lett. 23 (2013) 2984–2989
2987
is observed in hippocampus, cortex and hypothalamus in patients
processes in both young and aged rats.31 Therefore, in vivo AChE
activity was determined which showed that all the synthesized
compounds inhibited the AChE activity in distinct brain regions
prefrontal cortex, hippocampus and hypothalamus compared to
control [p <0.01, p <0.05 and p <0.001], respectively (Fig. 2). These
results also confirmed that anilide and imide derivatives of 4AP
significantly enhanced cholinergic neurotransmission in these dis-
tinct brain regions and attributed to enhanced learning and mem-
ory functions due to their anti-cholinesterase activity. Acute
toxicity studies didn’t show any signs of toxicity and mortality
with dementia of Alzheimer’s Type (DAT).2
7,28
Hippocampus is per-
manently involved in memories that have to be acquired and re-
trieved. It is also temporarily involved in memory consolidation
and as an area for the temporary storage of the to-be-consolidated
2
9
information. This information is further transferred into prefron-
tal cortex where short-term memory is converted into long term
memory (a process called as consolidation).30 It has also been re-
ported through several Investigations that, hypothalamus stimula-
tion facilitates hippocampus dependent learning and memory
Figure 4. Docking model of compound [A] 4APMb and [B] Donepezil at the active sites of AChE. The hydrogen bonds are displayed as dashed yellow.

2
988
S. K. Sinha, S. K. Shrivastava / Bioorg. Med. Chem. Lett. 23 (2013) 2984–2989
up to a dose of 100 mg/kg of body weight as evident through a nor-
mal behavioral pattern of rats up to the desired period of observa-
tion (details in Supplementary data).
The synthesized compounds 4APSb and 4APMb showed much
better AChE and BChE inhibitory activity, reversing acute memory
loss and learning impairment as compared to 4APSa and 4APMa.
On first day 4APMb produced lesser transfer latency (61.33 ±
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.bmcl.2013.03.
026. These data include MOL files and InChiKeys of the most
important compounds described in this article.
0
.61 s) compared to scopolamine treated group (86.83 ± 0.90 s).
References and notes
However, on second day transfer latency (53.83 ± 0.60 s) was lesser
than first day, which illustrated the beneficial role of 4APMb in
reversing acute memory loss and learning impairment compared
to other derivatives and donepezil in both dose level.
1
2
.
.
Bartus, R. T.; Dean, R. L.; Beer, B.; Lippa, A. S. Science 1982, 217, 408.
Perry, E. K.; Perry, R. H.; Blessed, G.; Tomlinson, B. E. Neuropathol. Appl.
Neurobiol. 1978, 4, 273.
3. Gil-Bea, F. J.; Garcia-Alloza, M.; Dominguez, J.; Marcos, B.; Ramirez, M. J.
Neurosci. Lett. 2005, 375, 37.
Hakansson, L. Acta Neurol. Scand. 1993, 88, 7.
The crystal structure of AChE with high resolution was retrieved
from the protein data bank (pdb code: 1B41).32 The structure was
prepared in the following procedures by protein preparation wiz-
ard in Maestro 9.2 (Schrödinger, LLC, 2011), including adding
hydrogens, assigning partial charges using the OPLS-2005 force
field and assigning protonation states, and a restrained, partial en-
ergy minimization. Finally, the cocrystal ligand (snake-venom tox-
in fasciculin-II) was removed, and the resulting structure was used
as the receptor model in docking studies. Docking studies were
carried out to provide a better interpretation of the biological pro-
file of 4APMb and donepezil toward AChE. It was observed that
4.
5. Giacobini, E. Aging (Milano) 2001, 13, 247.
6. Lahiri, D. K.; Farlow, M. R.; Greig, N. H.; Sambamurti, K. Drug Dev. Res. 2002, 56,
267.
7.
Polman, C. H.; Bertelsmann, F. W.; van Loenen, A. C.; Koeteier, J. C. Arch. Neurol.
994, 51, 292.
Stork, C. M.; Hoffman, R. S. J. Toxicol. Clin. Toxicol. 1994, 32, 583.
1
8
.
9. Murray, N. M. F.; Newsome-Davis, J. Neurology 1981, 31, 265.
1
0. Galisteo, M.; Rissel, M.; Sergent, O.; Chevanne, M.; Cillard, J.; Guillouzo, A.;
Lagadic-Gossmann, D. J. Pharmacol. Exp. Ther. 2000, 294, 160.
1. Birks, J.; Wilcock, G. K. Cochrane Database Syst. Rev. 2004. http://dx.doi.org/
10.1002/14651858.CD004748. Art. No.: CD004748.
2. Moskovskij, N. I.; Grigorieva, I. V.; Sokolchik, E. I. Zh. Nevrol. Psikhiatr. Im. S S
Korsakova 1991, 91, 53.
1
1
1
1
1
1
1
4
APMb and donepezil were properly positioned into the enzyme
gorge and showed interaction with the internal amino acid residue
Tyr-341 and Trp-286 by means of a interaction. The 4AP ring
3. Scipione, L.; De Vita, D.; Musella, A.; Flammini, L.; Bertoni, S.; Barocelli, E.
Bioorg. Med. Chem. Lett. 2008, 18, 309.
4. Cavallito, C. J.; Yun, H. S.; Edwards, M. L.; Foldes, F. F. J. Med. Chem. 1971, 14,
p–p
130.
of 4APMb was well placed in the hydrophobic pockets formed by
Tyr-341, Trp-286, Val-294, Phe-297, Leu-289, Tyr-124 and Tyr-72
and exhibited strong hydrophobic interactions (Fig. 3). The study
clearly demonstrated that both compounds were able to bind with
the key peripheral anionic site (PAS) residue Trp-286, Tyr-124 and
Tyr-341. The carbonyl oxygen of 4APMb was involved in forming a
bifurcated hydrogen bond with Phe-295 (determine substrate
specificity) and Arg-296. Introduction of carbon-carbon unsatura-
tion in case of 4APMb results high G-score (À7.16) indicates the
high binding ability in comparison of other derivatives suggested
the molecular flexibility on biological activity. The methoxy group
of donepezil was observed in establishing the H-bond with Phe-
5. Trujillo-Ferrara, J.; Montoya Cano, L.; Espinoza-Fonseca, M. Bioorg. Med. Chem.
Lett. 2003, 13, 1825.
6. Correa-Basurto, J.; Alcantara, I. V.; Espinoza-Fonseca, L. M.; Trujillo-Ferrara, J.
G. Eur. J. Med. Chem. 2005, 40, 732.
7. Andreani, A.; Leoni, A.; Locatelli, A.; Morigi, R.; Rambaldi, M.; Pietra, C.; Villetti,
G. Eur. J. Med. Chem. 2000, 35, 77.
18. Barak, D.; Kronman, C.; Ordentlich, A.; Ariel, N.; Bromberg, A.; Marcus, D.;
Lazar, A.; Velan, B.; Shafferman, A. J. Biol. Chem. 1994, 269, 6296.
1
9. Sinha, S. K.; Shrivastava, S. K. Med. Chem. Res. 2012, 19. http://dx.doi.org/
0.1007/s00044-012-9982-4.
20. General procedure for the synthesis of compounds
-oxo-4-(pyridin-4-ylamino)butanoic acid (4APSa)
AP (0.470 g, 5 mmol) was dissolved in 5 ml of tetrahydrofurane in a 25-ml
1
4
4
conical flask. To this solution equimolar quantity (0.5 g, 5 mmol) of succinic
anhydride was added and reaction mixture was stirring up to 3 h at 25 °C. The
reaction progress was monitored by TLC using mobile phase as
chloroform:methanol (6:4). On completion of reaction the resultant product
2
95 backbone, suggested that the compounds might probably act
33,34
via the AChE inhibition (Fig. 4).
ADME or Pharmacokinetic
4APSa was collected by filtration then washed three times with 0.001 M HCl
properties were also predicted for all the compounds by using
the QikProp 3.4 module of the software consisting of principal
descriptors and physiochemical properties with analysis of the
logP (octanol/water), % human oral absorption, Lipinski’s rule of
five violation, CNS activity and permeability through MDCK (Ma-
din-Darby Canine Kidney) cells in nm/s etc. (MDCK cells are con-
sidered to be a good mimic for the blood–brain barrier).The
compounds 4APSb and 4APMb illustrated good oral absorption,
CNS activity and permeability through blood–brain barrier and
also satisfy Lipinski’s rule for drug likeliness of the synthesized
and crystallized from 95% ethanol. Yield: 81.6%, mp: 232–234 °C, R 0.50, IR
f
À1
(
(
KBr,
m
cm ): 3413 (OH), 3369 (NH), 2950 (CH, CH
2
), 1725 (CO, COOH), 1680
) (d ppm): 11.3 (s, 1H, COOH), 8.9 (s, 1H, NH),
.3–8.5 (m, 4H, pyridine ring), 2.9 (t, 2H, CH –COOH), 2.5 (t, 2H, CH –CONH);
C NMR (d ppm): 179 (CONH), 173 (COOH), 153, 149, 109 (pyridine ring), 30,
8 (CH ); Anal. Calcd for C : C, 55.67; H, 5.19; N, 14.43; Found: C,
4.78; H, 5.26; N, 14.10.
-(Pyridin-4-yl)pyrrolidine-2,5-dione (4APSb)
1
CO, CONH); H NMR (DMSO-d
6
8
2
2
1
3
2
5
1
2
9 10 2 3
H N O
A solution of 4APSa (0.970 g, 5 mmol) in anhydrous tetrahydrofuran (5 ml) and
equimolecular amount of sodium acetate (0.410 g) and acetic anhydride
(
0.5 ml) was heated and stirred at 60 °C for 5 h, followed by evaporation of the
solvent under vacuum. The residue was washed three times with 0.001 M HCl,
À1
yielding 4APSb. Yield: 72.6%, mp: 186–188 °C, R
(CH, CH
), 1690 (CO); 1H NMR (DMSO-d
ring), 2.7 (dt, 4H, CH2); C NMR (d ppm): 185 (CO); 153, 149, 109 (pyridine
ring), 35 (CH ); Anal. Calcd for C : C, 61.36; H, 4.58; N, 15.90; Found: C,
0.28; H, 4.32; N, 15.48.
Z)-4-oxo-4-(pyridin-4-ylamino)but-2-enoic acid (4APMa)
AP (0.470 g, 5 mmol) was dissolved in 5 ml of tetrahydrofurane in a 25-ml
f
0.52, IR (KBr,
m
cm ): 2950
3
5
compounds.
2
6
) (d ppm): 8.3–8.5 (m, 4H, pyridine
13
2
9 8 2 2
H N O
6
(
4
Conclusions and future directions
Thus, from the above study we have successfully identified a
new class of potent cognition enhancing and antiamnesic drugs.
Among the identified compounds, compound 4APMb deserves fur-
ther clinical studies which can lead to a discovery of a new lead
having a potent cognition enhancing and antiamnesic properties.
conical flask. To this solution equimolar quantity (0.490 g, 5 mmol) of maleic
anhydride was added and reaction mixture was stirring up to 3 h at 25 °C. The
reaction progress was monitored by TLC using mobile phase as
chloroform:methanol (6:4). On completion of reaction the resultant product
4APMa was collected by filtration then washed three times with 0.001 M HCl
and crystallized from 95% ethanol. Yield: 78.6%, mp: 222–224 °C, R
f
0.42, IR
À1
(
KBr,
m
cm ): 3413 (OH), 3369 (NH), 3103 (CH, CH@CH), 1730 (CO, COOH),
1
6
1685 (CO, CONH); H NMR (DMSO-d ) (d ppm): 11.5 (s, 1H, COOH), 9.3 (s, 1H,
Acknowledgments
NH), 8.3–8.5 (m, 4H, pyridine ring), 6.9 (d, 1H, CH–COOH), 6.7 (t, 1H, CH–
CONH); 13C NMR (d ppm): 179 (CONH), 173 (COOH), 153, 149, 109 (pyridine
9 8 2 3
ring), 122 (CH@CH); Anal. Calcd for C H N O : C, 56.25; H, 4.20; N, 14.58;
Found: C, 56.80; H, 4.36; N, 14.23.
The authors gratefully acknowledge the University Grants Com-
mission (UGC), New Delhi, India for the financial support to Mr.
Saurabh K Sinha. Grant No. R/Dev./IX-Sch./(SRF-JRF) Pharm./15402.
1
-(Pyridin-4-yl)-1H-pyrrole-2,5-dione (4APMb)
A solution of 4APMa (0.960 g, 5 mmol) in anhydrous tetrahydrofuran (5 ml)

S. K. Sinha, S. K. Shrivastava / Bioorg. Med. Chem. Lett. 23 (2013) 2984–2989
2989
and equimolecular amount of sodium acetate (0.410 g) and acetic anhydride
0.5 ml) was heated and stirred at 60 °C for 5 h, followed by evaporation of the
26. Snyder, P. J.; Bednar, M. M.; Cromer, J. R.; Maruff, P. Alzheimers Dement. 2005, 1,
126.
27. Davies, P.; Maloney, A. J. Lancet 1976, 25, 1403.
28. Harley, C. W.; Lacaille, J. C.; Galway, M. Brain Res. 1983, 270, 335.
29. Knowlton, B. J.; Fanselow, M. S. Curr. Opin. Neurobiol. 1998, 8, 293.
30. Tronel, S.; Matthijs, G. P. F.; Susan, J. S. Learn. Mem. 2004, 11, 453.
31. Soriano-Mas, C.; Redolar-Ripoll, D.; Aldavert-Vera, L.; Morgado-Bernal, I.;
Segura-Torres, P. Behav. Brain Res. 2005, 160, 141.
(
solvent under vaccum. The residue was washed three times with 0.001 M HCl,
À1
yielding 4APMb. Yield: 74.8%, mp: 202–204 °C, R
f
0.38, IR (KBr,
m
cm ): 3127
1
(
CH, CH@CH), 1685 (CO); H NMR (DMSO-d
6
) (d ppm): 8.3–8.5 (m, 4H, pyridine
ring), 6.9 (dd, 2H, CH@CH); C NMR (d ppm): 190 (CO); 153, 149, 109 (pyridine
1
3
9 6 2 2
ring), 125 (CH@CH); Anal. Calcd for C H N O : C, 62.07; H, 3.47; N, 16.09;
Found: C, 61.85; H, 3.38; N, 16.22.
2
1. In vitro and in vivo estimation of acetylcholinesterase activity carried out
according to method described by Ellman (Biochem. Pharmacol., 1961, 7, 88–95)
and Zdrazilova (Z. Naturforsch., 2004, 59, 293–296). Detailed procedures are
described in Supplementary data.
2. Lineweaver, H.; Burk, D. J. Am. Chem. Soc. 1934, 56, 658.
3. Bartolini, M.; Bertucci, C.; Cavrini, V.; Andrisano, V. Biochem. Pharmacol. 2003,
32. Kryger, G.; Harel, M.; Giles, K.; Toker, L.; Velan, B.; Lazar, A.; Kronman, C.;
Barak, D.; Ariel, N.; Shafferman, A.; Silman, I.; Sussman, J. L. Acta Crystallogr.
Sect. D 2000, 56, 1385.
33. Friesner, R. A.; Banks, J. L.; Murphy, R. B.; Halgren, T. A.; Klicic, J. J.; Mainz, D. T.;
Repasky, M. P.; Knoll, E. H.; Shaw, D. E.; Shelley, M.; Perry, J. K.; Francis, P.;
Shenkin, P. S. J. Med. Chem. 2004, 47, 1739.
2
2
6
5, 407.
4. Sharma, A. C.; Kulkarni, S. K. Prog. Neuropsychopharmacol. Biol. Psychiatry 1992,
6, 117.
5. Itoh, J.; Nabeshima, T.; Kameyama, T. Psychopharmacology (Berl.) 1990, 101, 27.
34. Halgren, T. A.; Murphy, R. B.; Friesner, R. A.; Beard, H. S.; Frye, L. L.; Pollard, W.
T.; Banks, J. L. J. Med. Chem. 2004, 47, 1750.
35. Moorthy, N. S. H. N.; Karthikeyan, C.; Trivedi, P. Med. Chem. 2009, 5, 549.
2
2
1