Synthesis and Biological Activity of Some Benzochromenoquinolinones: Tacrine Analogs as Potent Anti-Alzheimer's Agents

Article abstract of DOI:10.1002/cbdv.201800488

Alzheimer's disease (AD) is a well-known neurodegenerative disorder affecting millions of old people worldwide and the corresponding epidemiological data emphasize the importance of the disease. As AD is a multifactorial illness, various single target directed drugs that have reached clinical trials have failed. Therefore, various factors associated with outset of AD have been considered in targeted drug discovery. In this work, various benzochromenoquinolinones were synthesized and evaluated for their cholinesterase and BACE1 inhibitory activities as well as neuroprotective and metal-chelating properties. Among the synthesized compounds, 14-amino-13-(3-nitrophenyl)-2,3,4,13-tetrahydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-7,12-dione (6m) depicted the best inhibitory activity toward acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with IC₅₀s of 0.86 and 6.03 μm, respectively. Also, the compound could inhibit β-secretase 1 (BACE1) with IC₅₀=19.60 μm and showed metal chelating ability toward Cu²⁺, Fe²⁺, and Zn²⁺. In addition, docking study demonstrated desirable interactions of compound 6m with amino acid residues characterizing AChE, BChE, and BACE1.

Full text of DOI:10.1002/cbdv.201800488

Title: Synthesis and biological activity of some
benzochromenoquinolinones: Tacrine analogues as potent anti-
Alzheimer’s agents
Authors: Mohammad Mahdavi, Roshanak Hariri, Seyedeh Sara
Mirfazli, Hania Lotfian, Arezoo Rastergari, Omidreza Firuzi,
Najmeh Edraki, Bagher Larijani, Tahmineh Akbarzadeh, and
Mina Saeedi
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Chem. Biodiversity 10.1002/cbdv.201800488
Link to VoR: http://dx.doi.org/10.1002/cbdv.201800488

10.1002/cbdv.201800488
Chemistry & Biodiversity
Synthesis and biological activity of some benzochromenoquinolinones: Tacrine analogues
as potent anti-Alzheimer’s agents
a
b
c
b
Mohammad Mahdavi , Roshanak Hariri , Seyedeh Sara Mirfazli , Hania Lotfian , Arezoo
Rastergari b, Omidreza Firuzi d, Najmeh Edraki d, Bagher Larijani a, Tahmineh Akbarzadeh b,e, Mina
Saeedi f,e

a
Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Research
Institute, Tehran University of Medical Sciences, Tehran, Iran
b
Department of Medicinal Chemistry, Faculty of Pharmacy, Tehran University of Medical
Sciences, Tehran, Iran
c Department of Medicinal Chemistry, School of Pharmacy-International Campus, Iran University
of Medical Sciences, Tehran, Iran
d
Medicinal and Natural Products Chemistry Research Center, Shiraz University of Medical
Sciences, Shiraz, Iran
e
Persian Medicine and Pharmacy Research Center, Tehran University of Medical Sciences,
Tehran, Iran
f Medicinal Plants Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences,
Tehran, Iran
This paper is dedicated to the memory of our unique teacher in Chemistry and Medicinal
Chemistry, Professor Abbas Shafiee.
Abstract
 Corresponding author. Tel.: +98-21-64122219; fax: +98-21-89785317
E-mail address: m-saeedi@tums.ac.ir (M. Saeedi)
1
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10.1002/cbdv.201800488
Chemistry & Biodiversity
Alzheimer’s disease (AD) is a well-known neurodegenerative disorder affecting millions of old
people worldwide and the corresponding epidemiological data emphasize the importance of the
disease. As AD is a multifactorial illness, various single-target directed drugs that have reached
clinical trials have failed. Therefore, various factors associated with outset of AD have been
considered in targeted drug discovery. In this work, various benzochromenoquinolinones were
synthesized and evaluated for their cholinesterase and BACE1 inhibitory activities as well as
neuroprotective and metal-chelating properties. Among the synthesized compounds, 14-amino-
13-(3-nitrophenyl)-3,4-dihydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-7,12(2H,13H)-dione
(6m) depicted the best inhibitory activity toward acetylcholinesterase (AChE) and
butyrylcholinesterase (BChE) with IC50s of 0.86 and 6.03 µM, respectively. Also, it could
inhibit β-secretase 1 (BACE1) with IC50 = 19.60 µM and showed metal chelating ability toward
Cu2+, Fe2+ and Zn2+. In addition, docking study demonstrated desirable interactions of compound
6m with amino acid residues characterizing AChE, BChE, and BACE1.
Keywords: Alzheimer’s, BACE1, Benzochromenoquinolinones, Cholinesterase, Docking study,
Neuroprotectivity, Tacrine
Introduction
Alzheimer's disease (AD) has recently emerged as a controversial neurodegenerative
diseases among elderly people.[1] Cognitive impairment and memory loss along with aggressive
behavior and severe changes in the personality are the remarkable problems faced by patients with
AD.[2] However, there is no definite cure to stop the progression of the disease and the current
drugs only provide symptomatic treatment of AD which is achieved by the acetylcholinesterase
inhibitors (AChEIs).[3] Now, it has been proved that different cellular processes such as reduction
2
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10.1002/cbdv.201800488
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of acetylcholine (ACh) in the brain,[4] tau protein aggregation,[5] extracellular plaque deposits of
the β-amyloid peptide (Aβ),[6] and metal homeostasis dysfunction[7] are involved in the creation
and progression of AD. Multi aspects of the disease have made it difficult and sometimes
impossible to be cured and hence, recent research has focused on this fact to develop efficient
multi-target compounds against AD.[8,9]
Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are two enzymes which
contribute to the hydrolysis of ACh into acetic acid and choline to allow the corresponding pieces
to be reused and renovated into new neurotransmitters for the next message.[10] Cholinesterase
inhibitors (ChEIs) are compounds which inhibit those enzymes from breaking down ACh in order
to increase its level and duration of action.[11] Currently, there are three FDA approved drugs
including rivastigmine, galantamine, and donepezil which are ChEIs.[12] It should be noted that
tacrine was the first accepted ChEI by FDA for the treatment of AD, however, it was removed
from the market due to its hepatotoxicity and lots of efforts were dedicated to develop synthesis
of tacrine analogs.[13-15] As the most effective approach to the symptomatic treatment of AD is still
inhibition of AChE and BChE, tacrine has been considered as the main scaffold and various tacrine
derivatives[16-20] especially multifunctional agents inhibiting β-amyloid aggregation, β-secretase,
monoamino oxidases, and tau protein phosphorylation have been designed and synthesized. They
also are capable of binding to biometals and scavenging reactive oxygen species (ROS) (Fig.
1).[21,22] Recently, analogues of anticholinesterase drugs such as donepezil and tacrine have been
investigated against depression.[23,24] It was revealed that they could improve cognition in
depressed people which may delay conversion to diagnosis of AD.
In order to meet our goal in developing novel anticholinesterase agents[25-29] which may
improve cognitive impairment, herein, we synthesized some benzochromenoquinolinone
3
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10.1002/cbdv.201800488
Chemistry & Biodiversity
derivatives and evaluated for their biological activities with the aim of developing anti-
Alzheimer’s agents.
Results and discussion
Design of Compounds
The rationale behind the design of compounds comes back to the hybridization of scaffolds
which have been endorsed for desired biological activities (Fig. 2). Tacrine moiety was considered
as the main core for inducing ChEI activity. It has been revealed that the replacement of benzene
fused ring by pyran moiety has led to potent pyranotacrines as ChE inhibitors.[30] As indicated by
Marco et al., 4H-pyrano[2,3-b]quinolone derivative (A)[31] showed AChEI activity with IC50 of
0.87 µM. Also, our previous study revealed that aminopyrazolopyranoquinolines (B and C) have
depicted potent AChE (IC50 = 2.77 µM) and BChE (IC50 = 0.06 µM) inhibitory activity.[18]
Moreover, Shafiee et al. reported different tacrine-based analogues and among them compound D
was found to be effective ChEI (AChEI, IC50 = 0.052 µM and BChEI, IC50 = 0.006 µM).[32] In a
study reported by Han et al.,[33] BACE1 inhibitory activity of bis(7)-tacrine was confirmed. Also,
1,4-naphthoquinones such as 2-hydroxy-1,4-naphthoquinone (E) have shown BACE1 inhibitory
activity (IC50 = 5.96 µM).[34] It seems that hybridization of the corresponding scaffolds leads to
obtain multi-target activity of synthesized compounds against AD.
Chemistry
Synthetic route for the preparation of benzochromenoquinolinone derivatives 6a-p is
demonstrated in Scheme 1. Initially, required 2-amino-4aryl-5,10-dioxo-5,10-dihydro-4H-
benzo[g]chromene-3-carbonitriles 4 were prepared easily according to the reaction reported in the
4
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10.1002/cbdv.201800488
Chemistry & Biodiversity
literature[35] by the reaction of 2-hydroxynaphthalene-1,4-dione 1, aromatic aldehydes 2,
malononitrile 3 in the presence of piperidine in refluxing ethanol. Finally, all derivatives 6 were
synthesized through the reaction of compound 4 and cyclohexanone 5 in the presence of AlCl3 in
dry 1,2-dichloroethan (DCE) under reflux conditions.
Pharmacology
AChE and BChE inhibitory activity
All synthesized novel benzochromenoquinolinone derivatives 6a-p were evaluated for
their cholinesterase inhibitory activity based on the modified Ellman’s method[36] comparing with
tacrine and rivastigmine as the reference drugs (Table 1). As can be seen in Table 1, the best AChEI
activity
was
obtained
by
14-amino-13-(3-nitrophenyl)-2,3,4,13-tetrahydro-1H-
benzo[6,7]chromeno[2,3-b]quinoline-7,12-dione (6m) with IC50 = 0.86 µM. It should be noted
that 14-amino-13-(4-fluorophenyl)-2,3,4,13-tetrahydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-
7,12-dione (6c) was also found as a strong anti-AChE agent with IC50 = 0.89 µM. It was revealed
that the presence of nitro and fluorine groups at 3- and 4- position of aryl group connected to
benzochromenoquinolinone moiety led to high AChEI activity. The significant point is related to
analogues of compounds 6m and 6c; compounds 6l/6n (IC50s = 4.22 µM /inactive) and 6b (IC50 =
>100 µM), respectively, proving remarkable reduction of AChEI activity. It was concluded that
the anti-AChE activity was directly depended on the electronic property and position of substituent
on the aryl ring. Changing substituents to chlorine afforded interesting results. The presence of
chlorine at 3- position of aryl group (6e) resulted in good AChEI activity (IC50 = 1.447 µM).
Changing the position of Cl led to the reduction of activity in such a manner that compounds 6d
and 6f demonstrated lower activity with IC50s = 5.312 and 14.395 µM, respectively. Also,
5
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10.1002/cbdv.201800488
Chemistry & Biodiversity
increasing the number of chlorine afforded good and moderate anti-AChE activity as compounds
6g and 6h showed IC50s = 7.57 and 27.52 µM, respectively. It was indicated that the presence of
Cl at 3- position of aryl group induced better activity as observed for the compound 6e but
increasing the number of Cl atom not only did not increase inhibitory activity but also decreased
the anti-AChE activity. Another instructive point came back to the presence of bromine on the aryl
group in compounds 6i-k. The best activity was obtained by compound 6j possessing 3-
bromophenyl with IC50 = 1.80 µM, whereas compounds 6i and 6k showed lower activity with
IC50s = 2.77 and 13.79 µM, respectively. Comparing the AChEI activity of halogenated derivative
(6b-k) revealed that the size of halogens played no significant role and their position on the aryl
moiety was found to be much more important factor in such a manner that the order of AChEI
activity of 2-halosubstituted derivatives was 2-Br>2-Cl>2-F. Conversely, the order of activity was
observed as 4-F>4-Br>4-Cl for 4-halosubstituted derivatives. The absence of a substituent on the
aryl moiety also led to good activity in compound 6a (IC50 = 1.71 µM) and the presence of methyl
group afforded good to moderated inhibitory activity in compounds 6o and 6p (IC50s = 3.01 and
13.95 µM, respectively).
As shown in Table 1, the anti-BChE activity of compounds 6a, 6b, 6f-i, 6k, 6l, 6n-p was
not significant, however, the best BChEI activity was obtained by compound 6m (IC50 = 6.03 µM)
which was also the most active AChEI. Compounds 6c, 6d, 6e, and 6j showed good to moderate
activity with IC50s = 13.85, 29.02, 27.31, and 15.63 µM, respectively. It seems that the presence
of an electron-withdrawing group at 3- position of aryl moiety induced strengthening effect on
BChEI activity as observed in the case of AChEI activity.
Kinetic studies of AChE and BChE inhibition
6
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Chemistry & Biodiversity
To study the inhibition mode of AChE and BChE induced by the most potent compound
6m, a kinetic study was conducted as the same as ChE inhibition assay.[15] As it is clear in Fig. 3
and 4, graphical analysis of the Lineweaver-Burk reciprocal plots showed a mixed type of
inhibition confirming the fact that compound 6m binds to the both peripheral anionic site (PAS)
and the catalytic anionic site (CAS) of both AChE and BChE. The inhibition constant for AChEI
and BChEI were calculated as Ki = 1.22 and 7.89 µM, respectively.
Beta secretase (BACE1) inhibitory activity
β-Secretase (BACE1) plays a remarkable role in the synthesis of neurotoxic β-amyloid
(Aβ) peptides in the brain and it remains to be a versatile and challenging target in AD drug
discovery development and clinical trials are under underway.[37] In this regard, the most active
anti-AChE compound 6m was evaluated for its BACE1 inhibitory activity which showed IC50 =
19.60± 0.9 µM comparing with OM99-2 (IC50 = 0.014±0.003 µM).
Neuroprotection effect against Aβ-induced damage
Neuroprotective effect of compound 6m against damage induced by Aβ25-35 was
investigated in PC12 cells by MTT assay. This compound showed no significant activity up to the
concentration of 25 µM.
Metal chelating
Role of oxidative stress in the pathogenesis of AD has been widely supported in the
literature since the level of lipid peroxidation, DNA and protein oxidation products increases in
the brain of patients with AD. Unregulated reaction of molecular oxygen with the redox active
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10.1002/cbdv.201800488
Chemistry & Biodiversity
metals such as Fe, Cu, and Zn leads to the generation of ROS.[38] However, the role of metal-ion
homeostasis especially in the central nervous system needs to be considered in design of anti-AD
agents. Herein, the most active ChE inhibitor 6m was studied for its chelating ability toward Cu2+,
Fe2+ and Zn2+ in methanol using UV-vis spectrophotometer. As can be seen in Fig. 5, UV
absorption of compound 6m depicted a blue shift with addition of Cu2+, Zn2+, and Fe2+ confirming
the interaction of 6m and those metal ions. It worth mentioning that compound 6m depicted more
strong interaction with Fe2+ as the higher change was observed in the wavelength of absorbance of
treated solution of compound 6m and ferrous ions.
1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity
Now, it is clear that oxidative damage is present within the brains of patients with AD.[39]
In this respect, compound 6m was candidate for the evaluation of anti-oxidant activity, DPPH
radical scavenging activity in comparison to hydroxyanisole (BHA) as a standard antioxidant.
However, it showed no remarkable antioxidant activitiy (IC50>500 µM).
Docking studies
AChE and BChE inhibitory activity of compound 6m
Molecular docking study was performed using smina in Linux platform. Compound 6m
was subjected to docking into the 3D structure of AChE (1EVE) and BChE (1P0P) by smina. The
range of minimized affinity values of the poses of compound 6m is −17.35 and −15.35 kcal/mol,
respectively. The interactions of the best-docked conformation of compound 6m with the active
site residues of 1EVE is depicted in Fig. 6. Significantly, it formed a hydrogen bond with Tyr334.
Comparative analysis of the interactions of compound 6m with the binding site residues of BChE
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Chemistry & Biodiversity
is depicted in Fig. 7. As shown in Fig. 7, ligand has formed four hydrogen bonds with Trp82,
Trp430, Tyr440 and His438 through nitrogen and oxygen of the ligand which enhanced binding
of ligand to the active site.
BACE1 inhibitory activity of compound 6m
Docking results related to BACE1 inhibitory activity indicated that compound 6m is
located in the binding site of BACE1 as the same as SC7 (crystal ligand). BACE1 inhibition values
of the compound 6m ligand is −10.33 kcal/mol. Interactions of compound 6m with the active site
residues of 2QP8 is figured out in Fig. 8. Hydrogen bond between Ser71 and nitro group is clearly
shown which fixed ligand binding to the active site. Other interactions are depicted in 2D diagram
presented in Fig. 8.
Binding mode of compound 6m
1EVE: It is well accommodated in the peripheral anionic site (PAS) and the catalytic site
(CAS) of AChE.[40] As shown in Fig. 6, there is a hydrogen bond between nitro group and Tyr334
in the PAS. There is a remarkable sandwich π-π hydrophobic interactions between southern site of
selected ligand (tetrahydroquinoline) and two amino acids residue (Trp84 and Phe330) from the
anionic site at the gorge opening. Another hydrophobic interaction was provided similarly between
quinoline moiety and Phe330. Van der Waals and pi-alkyl interactions were presented with Trp84
and Phe330 residues.
1P0P: Similarly, compound 6m oriented rigidly in the active site of 1P0P1. Nitro and
amino groups formed four hydrogen bonds with Tyr440, Trp430, Trp82 and His438 in the catalytic
triad and anionic site. Several pi-alkyl interactions were provided through the interactions of
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10.1002/cbdv.201800488
Chemistry & Biodiversity
quinoline as well as aryl moieties (of naphthoquinone) and Ala328. On the other side, quinoline
moiety and aryl ring connected to benzochromenoquinolinone moiety facilitated numerous π-π
hydrophobic interactions with Trp82 and His438 residues.
2QP8: Fig. 8 represents the binding mode of compound 6m with 2QP8. Hydrogen bonding
with Ser71 and hydrophobic interactions with Tyr132, Thr292, Gly291 and Ilu171 around
quinoline moiety and aryl ring as well as similar interaction with Gln134 in other side led to well
orientation of compound 6m in the active site. Also, Van der Waals interaction with amino acid
Gly74 and pi-alkyl interaction between aryl ring and Leu91 residue well fixed the compound in
the BACE1 active site.
Conclusion
In conclusion, a wide range of benzochromenoquinolinone derivatives were synthesized
and evaluated for their biological activity responsible for the creation of AD. They included
cholinesterase and BACE1 inhibitory activities as well as neuroprotective and metal-chelating
properties. Among the synthesized compounds, compound 6m depicted the best ChE and
BACE1 inhibitory activity. Also, it demonstrated metal chelating ability toward Cu2+, Fe2+ and
Zn2+. Desired biological activities and low hepatotoxicity[19] made these compounds as the
versatile anti-AD agents.
Experimental
1
Melting points were determined on a Kofler hot stage apparatus and are uncorrected. H
and 13C NMR spectra were recorded on a Bruker FT-500, using TMS as an internal standard. IR
10
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10.1002/cbdv.201800488
Chemistry & Biodiversity
spectra were obtained on a Nicolet Magna FTIR 550 spectrophotometer (KBr disks). Elemental
analysis was performed on an Elementar Analysensysteme GmbH Vario EL III CHNS mode.
General procedure for the synthesis of 2-amino-4arryl-5,10-dioxo-5,10-dihydro-4H-
benzo[g]chromene-3-carbonitriles 4
A mixture of hydroxynaphthalene-1,4-dione 1 (1 mmol), aromatic aldehydes 2 (1 mmol),
and malononitrile 3 (1.1 mmol) in the presence of piperidine (1 mmol) was heated in EtOH (10
mL) for 5 h under reflux conditions. After completion of reaction (checked by TLC), the solvent
was evaporated, the crude was extracted by chloroform and used for further reaction without
purification.
General procedure for the synthesis of benzochromenoquinolinone derivatives 6a-p
A mixture of compound 4 (1 mmol) and cyclohexanone (5) (1 mmol) was added to the
suspension of AlCl3 in dry DCE (2 mmol in 30 mL) and heated at reflux for 12 h. After completion
of reaction (checked by TLC), DCE was evaporated, the crude was extracted with ethyl acetate.
The organic phase was dried over Na2SO4 and the solvent was evaporated under vacuum. All
compounds were recrystallized from petroleum and ethyl acetate to give pure products 6.
14-Amino-13-phenyl-2,3,4,13-tetrahydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-7,12-dione
(6a)
Yield: 75%, mp> 250 °C, IR (KBr): 3435, 3250, 3055, 2850, 1650, 1452 cm-1. 1H NMR (500 MHz,
DMSO-d6): 8.03 (d, J = 7.0 Hz, 1H, H8), 7.92 (d, J = 7.0 Hz, 1H, H11), 7.82-7.81 (m , 2H, H9,
H10), 7.44 (d, J = 7.5 Hz, 2H, H2ʹ, H6ʹ), 7.22 (t, J = 7.5 Hz, 2H, H3ʹ, H5ʹ), 7.12 (t, J = 7.5 Hz, 1H,
H4ʹ), 5.82 (s, 2H, NH2), 5.43 (s, 1H, H13), 2.61-2.62 (m, 2H, H4), 2.35 (d, J = 16.5 Hz, 1H, H1),
11
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Chemistry & Biodiversity
2.19 (d, J = 16.5 Hz, 1H, H1), 1.71-1.69 (m, 4H, H2, H3). 13C NMR (125MHz, DMSO-d6): 182.6,
177.9, 153.4, 152.8, 151.5, 150.4, 142.8, 134.4, 133.8, 131.2, 130.6, 128.4, 128.2, 126.7, 126.0,
125.9, 122.9, 113.8, 97.7, 33.8, 32.0, 23.0, 22.2, 21.9. Anal. Calcd for C26H20N2O3: C, 76.45; H,
4.94; N, 6.86. Found: C, 76.21; H, 4.73; N, 6.64.
14-Amino-13-(2-fluorophenyl)-2,3,4,13-tetrahydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-
7,12-dione (6b)
1
Yield: 70%, mp > 250 °C. IR (KBr): 3420, 3252, 3055, 2850, 1645, 1443 cm-1. H NMR (500
MHz, DMSO-d6): 8.04 (d, J = 6.5 Hz, 1H, H8), 7.90 (d, J = 6.5 Hz, 1H, H11), 7.84-7.80 (m , 2H,
H9, H10), 7.72 (d, J = 8.0 Hz, 1H, H4ʹ), 7.21 (dd, J = 13.0, 8.0 Hz, 1H, H3ʹ), 7.12-7.09 (m, 1H,
H6ʹ), 7.07-7.03 (m, 1H, H5ʹ), 5.60 (s, 2H, NH2), 5.50 (s, 1H, H13), 2.59-2.57 (m, 2H, H4), 2.35
(d, J = 15.5 Hz, 1H, H1), 2.18 (d, J = 15.5 Hz, 1H, H1), 1.70-1.69 (m, 4H, H2, H3). 13CNMR (125
MHz, DMSO-d6): 182.5, 177.9, 160.4 (d, JC-F = 245 Hz), 153.2, 152.9, 151.4, 151.0, 142.0, 134.5,
133.9, 131.9, 131.1, 130.5, 129.2, 128.6 (d, JC-F = 12.5 Hz), 126.0 (d, JC-F = 21.5 Hz), 124.2, 120.5,
115.6 (d, JC-F = 21.5 Hz), 114.0, 96.2, 31.9, 30.0, 23.1, 22.9, 22.1. Anal. Calcd for C26H19FN2O3:
C, 73.23; H, 4.49; N, 6.57. Found: C, 73.53; H, 4.29; N, 6.27.
14-Amino-13-(4-fluorophenyl)-3,4-dihydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-
7,12(2H,13H)-dione (6c)
1
Yield: 74%, mp > 250 °C. IR (KBr): 3431, 3251, 3050, 2850, 1650, 1455 cm-1. H NMR (500
MHz, DMSO-d6): 8.03 (d, J = 7.0 Hz, 1H, H8), 7.92 (d, J = 7.0 Hz, 1H, H11), 7.82-7.81 (m , 2H,
H9, H10), 7.45-7.44 (m, 2H, H2ʹ, H6ʹ), 7.03 (t, J = 7.0 Hz, 2H, H3ʹ, H5ʹ), 5.84 (s, 2H, NH2), 5.44
(s, 1H, H13), 2.58-2.57 (m, 2H, H4), 2.35 (d, J = 16.0 Hz, 1H, H1), 2.18 (d, J = 16.0 Hz, 1H, H1),
1.70-1.69 (m, 4H, H2, H3). 13CNMR (125 MHz, DMSO-d6): 182.7, 177.9, 160.9 (d, JC-F = 242.5
Hz), 153.4, 152.9, 151.5, 150.5, 143.0, 139.0, 134.4, 133.9, 131.2, 130.5 (d, JC-F = 20.0 Hz), 126.1,
12
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Chemistry & Biodiversity
125.9, 122.7, 114.8 (d, JC-F = 22.5 Hz), 113.9, 97.5, 33.1, 32.1, 23.0, 22.1, 21.9. C26H19FN2O3: C,
73.23; H, 4.49; N, 6.57. Found: C, 73.12; H, 4.29; N, 6.25.
14-Amino-13-(2-chlorophenyl)-3,4-dihydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-
7,12(2H,13H)-dione (6d)
1
Yield: 75%, mp > 250 °C. IR (KBr): 3430, 3252, 3050, 2851, 1645, 1450 cm-1. H NMR (500
MHz, DMSO-d6): 8.05 (d, J = 7.0 Hz, 1H, H8 ), 7.87-7.81 (m, 3H, H9, H10, H11), 7.49 (d, J =
7.0 Hz, 1H, H3ʹ), 7.28 (d, J = 7.0 Hz, 1H, H6ʹ), 7.24-7.17 (m, 2H, H5ʹ, H4ʹ), 5.51(s, 1H, H13),
5.44 (s, 2H, NH2), 2.57-2.56 (m, 2H, H4), 2.31 (d, J = 16.0 Hz, 1H, H1), 2.17 (d, J = 16.0 Hz, 1H,
13
H1), 1.68-1.67 (m, 4H, H2 , H3). C NMR (125 MHz, DMSO-d6): 182.5, 177.8, 153.2, 153.0,
151.5, 150.8, 139.3, 134.5, 133.9, 132.4, 132.1, 131.0, 130.5, 129.6, 128.9, 127.7, 126.1, 125.9,
120.9, 114.0, 96.8, 33.1, 31.8, 22.9, 22.1, 21.8 . C26H19ClN2O3: C, 70.51; H, 4.32; N, 6.33. Found:
C, 70.21; H, 4.52; N, 6.52.
14-Amino-13-(3-chlorophenyl)-3,4-dihydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-
7,12(2H,13H)-dione (6e)
1
Yield: 75%, mp > 250 °C. IR (KBr): 3425, 3251, 3050, 2850, 1651, 1438 cm-1. H NMR (500
MHz, DMSO-d6): 8.05 (d, J = 6.5 Hz, 1H, H8 ), 7.88-7.82 (m, 3H, H9, H10, H11), 7.49 (s, 1H,
H2ʹ) 7.28 (d, J = 7.5 Hz, 1H, H4ʹ), 7.24-7.17 (m, 2H, H5ʹ, H6ʹ), 5.52 (s, 1H, H13), 5.45 (s, 2H,
NH2), 2.58-2.57 (m, 2H, H4), 2.32 (d, J = 15.5 Hz, 1H, H1), 2.18 (d, J = 15.5 Hz, 1H, H1), 1.70-
1.68 (m, 4H, H2 , H3). 13C NMR (125 MHz, DMSO-d6): 182.5, 177.8, 153.2, 153.0, 151.5, 150.8,
139.3, 134.6, 134.0 132.4, 132.1, 131.1, 130.5, 129.6, 128.9, 127.7, 126.0, 125.9, 120.9, 114.0,
96.8, 33.1, 31.8, 22.9, 22.1, 21.8. C26H19ClN2O3: C, 70.51; H, 4.32; N, 6.33. Found: C, 70.21; H,
4.55; N, 6.63.
13
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Chemistry & Biodiversity
14-Amino-13-(4-chlorophenyl)-3,4-dihydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-
7,12(2H,13H)-dione (6f)
1
Yield: 75%, mp > 250 °C. IR (KBr): 3450, 3261, 3055, 2856, 1651, 1428 cm-1. H NMR (500
MHz, DMSO-d6): 8.05 (d, J = 7.0 Hz, 1H, H8 ), 7.94 (dd, J = 7.0, 1.5 Hz, 1H, H11), 7.88-7.83
(m, 2H, H9, H10), 7.46 (d, J = 8.0 Hz, 2H, H3ʹ, H5ʹ) 7.28 (d, J = 8.0 Hz, 2H, H2ʹ, H6ʹ), 5.87 (s,
2H, NH2), 5.46 (s, 1H, H13), 2.60-2.58 (m, 2H, H4), 2.38-2.35 (d, J = 17.5 Hz, 1H, H1), 2.21-2.18
13
(d, J = 17.5 Hz, 1H, H1), 1.70-1.68 (m, 2H, H2, H3). C NMR (125 MHz, DMSO-d6): 182.6,
177.8, 153.3, 152.9, 151.5, 150.6, 141.7, 134.5, 133.5, 131.4, 131.2, 130.6, 130.5, 128.6, 128.0,
125.9, 122.4, 113.9, 97.5, 33.2, 31.9, 23.0, 22.2, 21.9. C26H19ClN2O3: C, 70.51; H, 4.32; N, 6.33.
Found: C, 70.31; H, 4.52; N, 6.13.
14-Amino-13-(2,3-dichlorophenyl)-3,4-dihydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-
7,12(2H,13H)-dione (6g)
1
Yield: 70%, mp > 250 °C. IR (KBr): 3432, 3250, 3050, 2852, 1650, 1440 cm-1. H NMR (500
MHz, DMSO-d6): 8.07 (d, J = 7.0 Hz, 1H, H8 ), 7.91 (d, J = 7.0 Hz, 1H, H11), 7.86-7.85 (m, 2H,
H9, H10), 7.55 (d, J = 7.5 Hz, 1H, H4ʹ) 7.49 (d, J = 7.5 Hz, 1H, H6ʹ), 7.28 (t, J = 7.5 Hz, 1H,
H5ʹ), 5.67(s, 1H, H13), 5.47 (s, 2H, NH2), 2.60-2.58 (m, 2H, H4), 2.35 (d, J = 17.0 Hz, 1H, H1),
2.20 (d, J = 17.0 Hz, 1H, H1), 1.71-1.69 (m, 4H, H2, H3). 13C NMR (125 MHz, DMSO-d6): 182.5,
177.9, 153.5, 153.2, 151.7, 150.8, 142.1, 139.5, 134.6, 132.4, 132.0, 131.1, 130.6, 129.8, 128.5,
126.0, 125.9, 120.3, 116.8, 114.3, 96.6, 33.3, 31.9, 22.9, 22.1, 21.8. C26H18Cl2N2O3 : C, 65.42; H,
3.80; N, 5.87. Found: C, 65.62; H, 4.1; N, 5.67.
14-Amino-13-(2,4-dichlorophenyl)-3,4-dihydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-
7,12(2H,13H)-dione (6h)
14
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Chemistry & Biodiversity
1
Yield: 70%, mp > 250 °C. IR (KBr): 3425, 3245, 3056, 2852, 1650, 1450 cm-1. H NMR (500
MHz, DMSO-d6): 8.06 (d, J = 6.5 Hz, 1H, H8 ), 7.90 (d, J = 6.5 Hz, 1H, H11), 7.84-7.83 (m, 2H,
H9, H10), 7.62 (d, J = 8.5 Hz, 1H, H5ʹ), 7.51(s, 1H, H3ʹ), 7.34 (d, J = 8.5 Hz, 1H, H6ʹ), 5.56 (s,
1H, H13), 5.46 (s, 2H, NH2), 2.59-2.58 (m, 2H, H4), 2.34 (d, J = 16.0 Hz, 1H, H1), 2.19 (d, J =
13
16.0 Hz, 1H, H1), 1.70-1.69 (m, 4H, H2, H3). C NMR (125 MHz, DMSO-d6): 182.5, 177.7,
153.3, 153.0, 151.5, 151.1, 138.3, 134.5, 133.9, 133.1, 132.5, 131.0, 130.5, 128.9, 127.8, 127.6,
126.2, 126.0, 120.2, 114.2, 96.3, 33.0, 31.9, 22.9, 22.1, 21.8. C26H18Cl2N2O3: C, 65.42; H, 3.80;
N, 5.87. Found: C, 65.72; H, 3.65; N, 5.57.
14-Amino-13-(2-bromophenyl)-3,4-dihydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-
7,12(2H,13H)-dione (6i)
1
Yield: 77%, mp > 250 °C. IR (KBr): 3430, 3250, 3045, 2856, 1645, 1450 cm-1. H NMR (500
MHz, CDCl3): 8.15 (d, J = 7.0 Hz, 1H, H8), 8.01(d, J = 7.0 Hz, 1H, H11), 7.70-7.69 (m, 2H, H9,
H10), 7.53 (d, J = 7.0 Hz, 1H, H3ʹ), 7.33 (d, J = 7.0 Hz, 1H, H6ʹ), 7.18-7.04 (m, 2H, H4ʹ, H5ʹ),
5.59 (s, 2H, H13), 4.62 (s, 2H, NH2), 2.80-2.78 (m, 2H, H4), 2.35-2.24 (m, 2H, H1), 1.82-1.79
(m, 4H, H2, H3). 13C NMR (125 MHz, CDCl3): 183.1, 177.7, 154.6, 153.2, 151.1, 150.9, 145.2,
141.6, 134.2, 133.6, 132.8, 131.5, 130.8, 129.1, 128.7, 126.6, 126.3, 123.2, 122.6, 114.3, 98.3,
35.6, 32.1, 23.1, 22.4, 22.2. C26H19BrN2O3: C, 64.08; H, 3.93; N, 5.75. Found: C, 64.38; H, 4.13;
N, 5.42.
14-Amino-13-(3-bromophenyl)-3,4-dihydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-
7,12(2H,13H)-dione (6j)
1
Yield: 77%, mp > 250 °C. IR (KBr): 3430, 3245, 3055, 2850, 1642, 1450 cm-1. H NMR (500
MHz, CDCl3): 8.11 (d, J = 7.0 Hz, 1H, H8), 8.00 (d, J = 7.0 Hz, 1H, H11), 7.70-7.68 (m, 2H, H9,
H10), 7.62 (s, 1H, H2ʹ), 7.22 (d, J = 7.5 Hz, 1H, H4ʹ), 7.07-7.01 (m, 2H, H5ʹ, H6ʹ), 5.61 (s, 2H,
15
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H13), 4.60 (s, 2H, NH2), 2.81-2.79 (m, 2H, H4), 2.33-2.28 (m, 2H, H1), 1.81-1.79 (m, 4H, H2,
H3). 13C NMR (125 MHz, CDCl3): 183.2, 178.0, 154.3, 153.0, 151.2, 150.4, 145.0, 141.2, 134.0,
133.4, 132.2, 131.3, 130.4, 129.0, 128.6, 126.4, 126.0, 123.7, 122.1, 114.4, 98.5, 35.4, 32.1, 23.2,
22.4, 22.1. C26H19BrN2O3: C, 64.08; H, 3.93; N, 5.75. Found: C, 64.30; H, 4.21; N, 5.40.
14-Amino-13-(4-bromophenyl)-3,4-dihydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-
7,12(2H,13H)-dione (6k)
1
Yield: 78%, mp > 250 °C. IR (KBr): 3430, 3245, 3052, 2850, 1650, 1450 cm-1. H NMR (500
MHz, CDCl3): 8.13 (d, J = 6.5 Hz, 1H, H8), 7.99 (d, J = 6.5 Hz, 1H, H11), 7.69-7.68 (m, 2H, H9,
H10), 7.39-7.33 (m, 4H, H2ʹ, H3ʹ, H5ʹ, H6ʹ), 5.24 (s, 1H, H13), 4.28 (s, 2H, NH2), 2.84-2.82 (m,
13
2H, H4), 2.38-2.30 (m, 2H, H1), 1.85-1.83 (m, 2H, H2, H3). C NMR (125 MHz, DMSO-d6):
183.2, 177.8, 155.0, 153.5, 150.9, 150.3, 140.6, 134.2, 133.7, 132.1, 131.6, 130.8, 130.6, 126.6,
126.3, 122.1, 121.7, 114.8, 98.0, 35.4, 32.3, 23.1, 22.4, 22.2. C26H19BrN2O3: C, 64.08; H, 3.93; N,
5.75. Found : C, 63.88; H, 3.68; N, 5.39.
14-Amino-13-(2-nitrophenyl)-3,4-dihydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-
7,12(2H,13H)-dione (6l)
°
1
Yield: 72%, mp> 250 C, IR (KBr): 3430, 3250, 3055, 2852, 1650, 1535, 1450, 1375 cm-1. H
NMR (500 MHz, DMSO-d6): 8.01 (d, J = 6.5 Hz , 1H, H8), 7.89 (d, J = 6.5 Hz , 1H, H11), 7.83-
7.80 (m, 3H, H9, H10, H3ʹ), 7.58 (t, J = 7.0 Hz , 1H, H5ʹ), 7.43 (t, J = 7.0 Hz , 1H, H4ʹ), 7.28 (d,
J = 7.0 Hz, 1H, H6ʹ), 5.92 (s, 2H, NH2), 5.79 (s, 1H, H13), 2.63-2.61 (m, 2H, H4), 2.36 (d, J =
16.5 Hz, 1H, H1), 2.21 (d, J = 16.5 Hz, 1H, H1), 1.73-1.71 (m, 4H, H2 , H3). 13C NMR (125 MHz,
DMSO-d6): 182.8, 177.6, 153.7, 153.4, 151.7, 150.0, 149.1, 136.5, 134.5, 134.2, 131.6, 130.7,
130.6, 128.6, 126.1, 125.9, 125.7, 124.1, 121.2, 114.3, 95.9, 31.9, 30.1, 22.9, 22.1, 21.8.
C26H19N3O5: C, 68.87; H, 4.22; N, 9.27. Found : C, 69.17; H, 4.52; N, 8.94.
16
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Chemistry & Biodiversity
14-Amino-13-(3-nitrophenyl)-3,4-dihydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-
7,12(2H,13H)-dione (6m)
°
1
Yield: 70%, mp> 250 C, IR (KBr): 3432, 3250, 3052, 2850, 1650, 1550, 1450, 1375 cm-1. H
NMR (500 MHz, DMSO-d6): 8.49 (s, 1H, H2ʹ), 8.04 (d, J = 7.5 Hz, 1H, H8), 7.99 (d, J = 7.5 Hz,
1H, H4ʹ), 7.92 (d, J = 7.5 Hz, 1H, H11), 7.80-7.79 (m, 3H, H9, H10, H6ʹ), 7.51 (t, J = 7.5 Hz, 1H,
H5ʹ), 5.99 (s, 2H, NH2), 5.64 (s, 1H, H13), 2.61-2.59 (m, 2H, H4), 2.35 (d, J = 16.5 Hz, 1H, H1),
13
2.10 (d, J = 16.5 Hz, 1H, H1), 1.71-1.69 (m, 4H, H2 , H3). C NMR (125 MHz, DMSO-d6):
182.6, 177.8, 153.3, 151.6, 150.9, 147.4, 144.8, 135.1, 134.4, 133.9, 131.1, 130.7, 129.7, 126.1,
125.8, 123.5, 122.1, 121.8, 121.6, 114.0, 95.8, 33.6, 32.1, 23.1, 22.1, 21.9.
C26H19N3O5: C, 68.87; H, 4.22; N, 9.27. Found: C, 68.52; H, 3.92; N, 8.94.
14-Amino-13-(4-nitrophenyl)-3,4-dihydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-
7,12(2H,13H)-dione (6n)
Yield: 75%, mp> 250 °C, IR (KBr): 3430, 3250, 3050, 2855, 1652, 1550, 1455, 1370 cm-1. 1H
NMR (500 MHz, DMSO-d6): 8.10 (d, J = 8.0 Hz, 2H, H3ʹ, H5ʹ), 8.05 (d, J = 7.5 Hz, 1H, H8),
7.92 (d, J = 7.5 Hz, 1H, H11), 7.85-7.82 (m, 2H, H9 , H10), 7.74 (d, J = 8.0 Hz, 2H, H2ʹ, H6ʹ),
5.94 (s, 2H, NH2), 5.64 (s, 1H, H13), 2.61-2.60 (m, 2H, H4), 2.36 (d, J = 17.5 Hz, 1H, H1), 2.16
(d, J = 17.5 Hz, 1H, H1), 1.72-1.70 (m, 4H, H2 , H3). 13C NMR (125 MHz, DMSO-d6): 182.6,
177.8, 153.3, 151.7, 150.9, 150.2, 146.3, 134.5, 133.9, 131.1, 130.7, 129.9, 126.1, 125.9, 123.3,
123.2, 121.6, 114.1, 98.7, 33.9, 32.1, 23.0, 22.1, 21.9 . C26H19N3O5: C, 68.87; H, 4.22; N, 9.27.
Found: C, 68.57; H, 4.45; N, 9.39.
14-Amino-13-(o-tolyl)-3,4-dihydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-7,12(2H,13H)-
dione (6o)
17
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Yield: 77%, mp> 250 °C, IR (KBr): 3435, 3250, 3050, 2850, 1650, 1452 cm-1. 1H NMR (500 MHz,
DMSO-d6): 8.05 (d, J = 7.5 Hz, 1H, H8 ), 7.90 (d, J = 7.5 Hz, 1H, H11 ), 7.83-7.82 (m, 2H, H9,
H10), 7.21-7.05 (m, 4H, H3ʹ, H4ʹ, H5ʹ, H6ʹ), 5.39 (s, 1H, H13), 5.24 (s, 2H, NH2), 2.64-2.60 (m,
5H, H4, CH3), 2.32 (d, J = 16.5 Hz, 1H, H1), 2.20 (d, J = 16.5 Hz, 1H, H1), 1.71-1.69 (m, 4H, H2,
13
H3). C NMR (125 MHz, DMSO-d6): 182.9, 177.9, 153.2, 153.0, 151.5, 150.4, 140.9, 135.5,
134.5, 133.9, 131.1, 130.6, 130.5, 130.2, 126.9, 126.5, 126.1, 125.8, 122.6, 114.3, 98.6, 32.3, 31.9,
22.9, 22.1, 21.9, 19.2. C27H22N2O3: C, 76.76; H, 5.25; N, 6.63. Found: C, 76.46; H, 5.55; N, 6.43.
14-Amino-13-(m-tolyl)-3,4-dihydro-1H-benzo[6,7]chromeno[2,3-b]quinoline-7,12(2H,13H)-
dione (6p)
Yield: 72%, mp> 250 °C, IR (KBr): 3432, 3255, 3050, 2852, 1650, 1450 cm-1. 1H NMR (500 MHz,
DMSO-d6): 8.11 (d, J = 7.0 Hz, 1H, H8), 7.98 (d, J = 7.0 Hz, 1H, H 11), 7.67-7.66 (m, 2H, H9,
H10), 7.28-7.00 (m, 4H, H2ʹ, H4ʹ, H5ʹ, H6ʹ), 5.87 (s, 2H, NH2), 5.36 (s, 1H, H13), 2.60-2.58 (m,
5H, H4, CH3), 2.24-2.16 (m, 2H, H1), 1.70-1.68 (m, 4H, H2, H3). 13C NMR (125 MHz, DMSO-
d6): 182.9, 177.9, 153.2, 153.0, 151.5, 150.4, 140.9, 135.5, 134.5, 133.9, 131.1, 130.6, 130.5,
130.2, 126.9, 126.5, 126.1, 125.8, 122.6, 114.3, 98.6, 32.3, 31.9, 22.9, 22.1, 21.9, 19.2.
C27H22N2O3: C, 76.76; H, 5.25; N, 6.63. Found: C, 76.96; H, 5.15; N, 6.75.
AChE and BChE inhibition assay
Acetylcholinesterase (AChE, E.C. 3.1.1.7, Type V-S, lyophilized powder, from electric
eel), butylcholinesterase (BChE, E.C. 3.1.1.8, from equine serum), acetylthiocholine iodide
(ATCI), butyrylthiocholine iodide (BTCI) and 5,5-dithiobis-(2-nitrobenzoic acid) (DTNB) were
obtained from Sigma. Potassium dihydrogen phosphate, dipotassium hydrogen phosphate,
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10.1002/cbdv.201800488
Chemistry & Biodiversity
potassium hydroxide, and sodium hydrogen carbonate were purchased from Fluka. The assay was
performed according to our previous reports based on modified Ellman’s method.[15]
Kinetic studies of AChE and BChE inhibition
For estimates of the inhibition model and inhibition constant Ki, reciprocal plots
of 1/V versus 1/[S] were obtained using different concentrations of the substrate. For this purpose,
experiments were performed similar to enzyme inhibition assay.[15] The rate of enzymatic reaction
was obtained with different concentrations of inhibitor and in the absence of inhibitor. For each
experiment, reaction was started by adding substrate and progress curves were recorded at 405 nm
within 2 min. Next, double reciprocal plots (1/v vs. 1/[s]) were made using the slopes of progress
curves to obtain the type of inhibition. Slopes of these reciprocal plots were then plotted against
the concentration of compound in a weighted analysis, and Ki was determined as the intercept on
the negative x-axis. All rate measurements were performed in triplicate and data analysis was
performed with Microsoft Excel 2003.
BACE1 inhibitory activity
The BACE1 enzyme inhibition assay was achieved by a FRET (Forster resonance
energy transfer) kit, from Invitrogen (former Pan Vera corporation, Madison, WI) as described by
the manufacturer instructions comparing with OM99-2 as the reference inhibitor.[41]
Protection of neuronal PC12 cells against Aβ-induced damage
The ability of compound 6m in protecting neuronal PC12 cells against damage induced by Aβ25-
was examined by the MTT assay as previously described in the literature.[41] PC12 (rat
35
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10.1002/cbdv.201800488
Chemistry & Biodiversity
pheochromocytoma) cells were a generous gift from Professor Lloyd A. Greene (Department of
Pathology and Cell Biology, Columbia University, New York, NY).
Metal chelating
All solutions used in metal-chelating study were prepared in methanol and Fe2+, Cu2+, and
Zn2+ solutions were prepared from FeSO4, CuCl2 or and ZnCl2 respectively. To study the metal
binding ability, a mixture of compound 6m (1 mL) and metal solution (1 mL) with the same
concentration (20 µM) in a 1 cm quartz cuvette was incubated at room temperature for 30 min.
Then, the absorption spectra were recorded with wavelength ranging from 200–500 nm.[42]
DPPH radical scavenging activity
Antioxidant activity of compound 6m was tested using DPPH (1,1-diphenyl-2-
picrylhydrazyl) according to our previous report.[15]
Molecular docking study
Molecular docking study was performed to explore the possible binding mode of the most
active compound 6m with AChE (PDB code 1EVE), BChE (PDB code 1P0P) and BACE1 (PDB
code 2QP8) using smina in Linux platform. Smina is a fork of AutoDock Vina that provides
enhanced support for scoring function.[43] The scoring function of smina does a better job sampling
low root mean squared deviation (RMSD) poses when compared to the default Auto Dock Vina
scoring function. The bounding box for docking is specified automatically with the autobox ligand
option. It generates a box with an 8 Å buffer around the reference ligand in the active site. For
each final pose, the affinity was reported as the negative value, the higher value indicated a more
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10.1002/cbdv.201800488
Chemistry & Biodiversity
favorable binding pose. In order to confirm the validity of the docking protocol, RMSD value was
measured between the crystal ligand (donepezil) pose and the generated nine poses of redocked
donepezil pose (2 Å) in 1EVE and 1P0P. The minimized affinity values for generated poses of
redocked crystal ligand pose were −10.92 kcal/mol. In addition, all RMSD values are less than 2
Å for 2QP8 and the minimized affinity values for generated poses of redocked crystal ligand pose
were −9.29 kcal/mol.
Acknowledgments
This work was supported by grants from the Research Council of Tehran University of Medical
Sciences with project No. 95-03-96-33001.
Author Contribution Statement
Mohammad Mahdavi contributed to the design of compounds and preparation of
manuscript. Roshanak Hariri and Hania Lotfian performed biological tests. Seyedeh Sara Mirfazli
performed the docking study. Najmeh Edraki and Omidreza Firuzi supervised biological tests.
Arezoo Rastergari contributed to the synthesis of compounds. Bagher Larijani and Tahmineh
Akbarzadeh contributed to the preparation of the manuscript. Mina Saeedi supervised all phases
of the study.
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Chemistry & Biodiversity
N
O
HO
O
N
Cl
H
N
NH
N
H
O
N
IC50 (eeAChE) = 3.9 nM
IC50 (hAChE ) = 65.2 nM
N
N
OMe
[13]
IC50 (AChE) = 0.521
[14]
M
H3C
O
O
N
N
N
O
Ar
NH2
NH2
NH
Tacrine
IC50 (AChE) = 0.37
[15]
M
N
N
N
NH2
HN
OMe
M
IC50 (BChE) = 0.055
[14]
N
N
N
N
N
O
N
Ph
CN
IC50 (AChE) = 2.77
[16]
M
IC50 (rAChE) = 3.319
[17]
M
O
O
N
O
Ar NH2
Designed compounds
Fig. 1. Different tacrine analogues possessing anti-ChE activity.
29
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