Docking studies and α-substitution effects on the anti-inflammatory activity of β-hydroxy-β-arylpropanoic acids

Article abstract of DOI:10.3390/molecules16086645

Six β -hydroxy-β -aryl propanoic acids were synthesised using a modification of Reformatsky reaction which has already been reported. These acids belong to the aryl propanoic acid class of compounds, structurally similar to the NSAIDs, such as ibuprofen,

Full text of DOI:10.3390/molecules16086645

Molecules 2011, 16, 6645-6655; doi:10.3390/molecules16086645
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molecules
ISSN 1420-3049
www.mdpi.com/journal/molecules
Article
Docking Studies and α-Substitution Effects on the
Anti-Inflammatory Activity of β-Hydroxy-β-arylpropanoic
Acids
Jelena S. Savić 1,*, Sanda P. Dilber 2 Bojan D. Marković 1, Marina T. Milenković 3,
,
Sote M. Vladimirov 1 and Ivan O. Juranić 4
1
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Belgrade,
Vojvode Stepe 450, 11221 Belgrade, Serbia
2
Department of Organic Chemistry, Faculty of Pharmacy, University of Belgrade,
Vojvode Stepe 450, 11221 Belgrade, Serbia
3
Department of Molecular Biology and Immunology, University of Belgrade, Vojvode Stepe 450,
11221 Belgrade, Serbia
4
Department of Organic Chemistry, Faculty of Chemistry, University of Belgrade, Box 158, 11001,
Belgrade, Serbia
* Author to whom correspondence should be addressed; E-Mail: jelena.savic@pharmacy.bg.ac.rs;
Tel.: +381-11-3951-335; Fax: +381-11-3872-840.
Received: 2 June 2011; in revised form: 26 July 2011 / Accepted: 3 August 2011 /
Published: 5 August 2011
Abstract: Six β-hydroxy-β-aryl propanoic acids were synthesised using a modification of
Reformatsky reaction which has already been reported. These acids belong to the aryl
propanoic acid class of compounds, structurally similar to the NSAIDs, such as ibuprofen,
and an anti-inflammatory activity is thus expected. The aim of this work was to determine
anti-inflammatory activity, examine gastric tolerability, and to carry out molecular docking
experiments to identify potential COX-2 inhibitors among the β-hydroxy-β-aryl propanoic
acids, and to elucidate the effect α-methyl substitution on the anti-inflammatory activity.
Anti-inflammatory activity and gastric tolerability were determined on rats using
carragenan induced paw oedema method, and docking studies were carried out using
Autodock v4.0.1. The range of ED50 values is between 127 µmol/kg and 15 µmol/kg, while
the result for ibuprofen is 51.7 µmol/kg. Only slight hyperaemia or few petechiae were
spotted on rat’s stomach. The results indicate that all compounds possess significant anti-

Molecules 2011, 16
inflammatory activity after oral administration, and that 2-methyl-3-hydroxy-3,3-diphenyl-
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propanoic acid has greatest activity, surpassing that of ibuprofen, a standard NSAID.
Another compound, 3-hydroxy-3,3-diphenylpropanoic acid, shows activity matching that
of ibuprofen, and is non-chiral and is proven to be non-toxic. The most of investigated
compounds have interactions with P3 anchor site like COX-2 selective inhibitors. No tested
substances or ibuprofen produced any significant gastric lesions.
Keywords: β-hydroxy-β-arylpropanoic acids; Reformatsky reaction; anti-inflammatory
activity; molecular docking simulations; COX-2 selective inhibitor
1. Introduction
Cyclooxygenase (COX), also known as prostaglandin endoperoxide synthase, is a bifunctional
enzyme that catalyzes the conversion of arachidonic acid to prostaglandin (PG) H2, the immediate
precursor to prostaglandins, thromboxane and prostacyclin. The conversion of arachidonic acid into
PGH2 proceeds through two separate reactions in which two molecules of O2 are incorporated into
arachidonic acid bound in the COX site to form PGG2, which then diffuses to the peroxidase site
(POX) to undergo a two-electron reduction to form the final product PGH2. Prostaglandins (PGs) are
the lipid mediators made by most cells in the body except by red blood cells and released upon almost
any type of chemical or mechanical stimulus [1]. The two definitely known isoforms of COX, named
COX-1 and COX-2 show distinct expressions patterns and distinct biological activities. COX-1 Is
formed in many different cells to create prostaglandins that serve for basic "housekeeping" messages
throughout the body. This is a constitutively expressed protein that is responsible for the physiological
production of prostaglandins. The COX-1 variant protein, named COX-3, is sensitive to inhibition with
paracetamol [2]. COX-2 is only formed in special cells and is used for signalling both the pain and
inflammation. This isoform is also called inducible isoform of enzyme COX [3]. In inflammatory
processes COX-2 is overexpressed.
Non-steroidal anti-inflammatory drugs (NSAIDs) are COX inhibitors and prevent PG synthesis,
thus exhibiting analgesic, antipyretic and anti-inflammatory actions. However, NSAIDs have a number
of adverse effects, mainly because of their inhibition of the constitutive isoform of COX. The major
adverse effects of NSAIDs are gastrotoxic (e.g., damage of gastric mucosa, may provoke gastric
bleeding and gastroduodenal ulcers), increased bleeding tendency and delay of the birth process [1].
Nowadays, there are known two types of COX inhibitors, nonselective, i.e., both COX-1 and COX-2
inhibitors, and predominantly selective COX-2 inhibitors such as the "coxibs". Since selective COX-2
inhibitors fail to inhibit constitutive COX-1 isoform, they have no gastrointestinal adverse effects.
However, recent publications have suggested that COX-2 inhibitors, like rofecoxib and celecoxib, may
be prothrombic and increase the risk of myocardial infarction [2]. Consequently, a synthesis of new
NSAIDs, with potent anti-inflammatory, analgesic and antipyretic action, but with no adverse effects is
highly desired.
We have synthesized six β-hydroxy-β-aryl propanoic acids having none, one, or two methyl groups
at the α-position. These acids are structurally similar to COX inhibitors: p-isobutylphenyl acetic

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acid (ibufenac), 4-biphenylacetic acid (felbinac), α-(4-isobutylphenyl)propanoic acid (ibuprofen),
α-(6-methoxy-2-naphtyl)propanoic acid (naproxen). The compounds studied in this work are among
compounds studied in our previous article and they affected the survival of HeLa cells (Human cervix
epithelial adenocarcinoma cells), having IC50 values from 62.20 to 185.55 μM/L. Generally, the
examined compounds did not affect proliferation of healthy human peripheral mononuclear cells
(PBMC) IC50 > 300 μM/L [4]. Some of synthesized acids exhibit anti-inflammatory activity [5]. In
this work, docking studies and α-substitution effect on the anti-inflammatory activity and gastric
tolerability of the synthesized compounds were evaluated.
2. Results and Discussion
β-Hydroxy-β-aryl propanoic acids were synthesized by the two-step reaction. In the first step
α-bromoalkanoic acid 1-ethoxyethyl ester intermediates were synthesized. The second step involved a
Reformatsky reaction in tetrahydrofuran (THF) at –5 to 10 °C between the previously synthesized
intermediates and 4-acetylbiphenyl or benzophenone in the presence of Zn (Scheme 1).
Scheme 1. Synthetic sequence of β-hydroxy-β-arylpropanoic acids.
Br
R2
C6H6
R1
COOH
O
O
+
O
R1
R2
Br
Br
O
OZnBr O
O
Zn, THF
0 °C
+
O
O
R1
R3
O
O
R3
R4
R2
R4
R2
R1
O
OZnBr O
OH
R4
O
H3O+
R3
O
O
R3
OH
R4
R2
R2
R1
R1
R1 = H, CH3
R2 = H, CH3
R3 =
R4 = CH3
The syntheses and antiproliferative activity of some β-hydroxy-β-arylpropanoic acids were
previously reported [4,5]. 3-Hydroxy-2-methyl-3-(4-diphenylyl)butanoic acid (2) was prepared by the
general method described above and fully characterized. The resulting mixture of diastereomers was
not separated. We observed a single spot on TLC, and assumed to have obtained a threo isomer, which
has optimal geometry containing an intramolecular hydrogen bond and the most distant methyl groups.

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Synthesized acids shown in Figure 1 are 3-hydroxy-3-(4-diphenylyl)butanoic acid (1), 3-hydroxy-2-
methyl-3-(4-diphenylyl)butanoic acid (2), 3-hydroxy-2,2-dimethyl-3-(4-diphenylyl)butanoic acid (3),
3-hydroxy-3,3-diphenylpropanoic acid (4), 3-hydroxy-3,3-diphenyl-2-methylpropanoic acid (5) and 3-
hydroxy-3,3-diphenyl-2.2-dimethylpropanoic acid (6).
Figure 1. Structures of the studied compounds.
COOH
COOH
COOH
OH
OH
OH
COOH
Ibuprofen
1
2
3
HO
COOH
HO
COOH
HO
COOH
4
5
6
2.1. Anti-inflammatory activity: carragenan-induced paw-oedema
Results showed that all compounds (save compound 3) produced significant, dose-dependent (like
ibuprofen) anti-inflammatory effect (Figure 2). ED50 Values were calculated for ibuprofen and for our
six compounds (Table 1).
Figure 2. Dose dependence of anti-inflammatory effect of studied compounds listed on legend.
120
100
80
60
40
20
0
ibuprofen
compound 1
compound 2
compound 3
compound 4
compound 5
compound 6
2,5
5
10
15
20
Administered dose (mg/kg)

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Table 1. Binding energies of top scored solutions as resulting from docking experiments,
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and corresponding standard biological response of studied compounds.
Binding energy (kcal/mol)
Compound
ED50
COX-1
–6.47
COX-2
–6.21
(μM/Kg)
R
S
R
S
Ibuprofen
51.70*
–6.74
–8.21
–8.16
–8.61
–8.16
–8.15
–8.13
–8.18
–8.13
-7.31
–7.20
–6.78
–7.50
–6.05
–8.31
–8.15
–8.50
–8.49
–8.14
–8.27
–8.25
–8.21
–6.92
–7.33
–7.14
–6.85
R
S
R
S
Compound 1
52.71**
2R3R
2R3S
2S3R
2S3S
R
2R3R
2R3S
2S3R
2S3S
R
Compound 2
70.10*
Compound 3
Compound 4
Compound 5
Compound 6
126.82*
50.00
S
S
R
S
R
S
14.79*
74.69
* Result obtained for mixture of enantiomers; **Result obtained for mixture of diastereomers.
2.2. Gastric tolerability
None of the tested substances (including ibuprofen) produced any significant gastric lesions. The
changes observed were in range of 0–1 according to the Adami's scoring scale. Namely, only slight
hyperemia or few petechiae were registered in rat stomach regardless of given dose.
2.3. Molecular docking computational experiments
Table 1 shows the binding energies of the top scored solutions found during docking experiments of
compounds 1–6 and ibuprofen (specific ligand for COX-1), along with ED50 values (μM/kg) obtained
in the carrageenan-induced rat paw oedema test. In this table, the result for SC-558 (a specific ligand
for COX-2) was not included, because of having a markedly different structure and the lack of a
biological assay for it.
Analysis of docking results reveals the modes of the binding between ligands and active site of
enzymes. Acids 1, 2 and 3 form strong interactions, which includes salt bridges with Arg120 (1-1.67
Ǻ, 2-1.92 Ǻ and 3-1.95 Ǻ) and hydrogen bonds with phenolic hydroxyl of Tyr 355 (1-2.7 Ǻ, 2-2.03 Ǻ
and 3-4.9 Ǻ), in first anchor site, P1. Compounds 1, 2 and 3 form similar hydrophobic interactions with
Ser 353 (∼3 Ǻ) and with Val 349 (∼3 Ǻ) but acid 1 forms π→ cation interactions with residues His 90,
Arg 513 and Gln 192 (∼3 Ǻ), (Figure 3).

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Figure 3. Superimposition of most favorable conformations of compounds 1 (green),
2 (blue) and 3 (magenta) docked into binding site of COX-2 receptor [6].
Acids 4, 5 and 6 form interactions with amino acid residues into all three cyclooxygenase anchor
sites and they act as selective COX-2 inhibitors.
Molecular docking experiments gave a reasonable explanations for different anti-inflammatory
activity of synthesized β-hydroxy-β-arylpropanoic acids. All synthesized compounds show improved
binding energies compared to the active ibuprofen. Differences in binding energies of enantiomers are
not significant. The carboxylate terminal groups of these molecules differ primarily in sterical
hindrance caused by the presence or absence of an α- and β-methyl group(s). Despite these
differences, the carboxylate groups of all compounds are essentially superimposable. The inhibitor
carboxylate participates in a network of polar interactions, which includes salt bridges between the
inhibitor and Arg 120 and hydrogen bonds of the inhibitor and phenolic hydroxyl of Tyr 355 (first
anchor site, P1). These amino acid residues together with His 90 and Glu 524 tightly lock inhibitors
into cyclooxygenase active site [6]. Methyl groups form hydrophobic interactions with Ser 353 and
Val 349 (<4 Ǻ). Substituents attached to a phenyl ring placed in β-position in respect to COOH of
inhibitors (isobutyl group of ibuprofen, second phenyl ring of all compounds) lie in hydrophobic
cleft (second anchor site, P2) that is lined with Leu 352, Tyr 385, Trp 387, Phe 518, Gly 526 and
Ser 530 residues.
Methyl groups, particularly two methyl groups at the α-position, move the whole molecule towards
the hydrophilic pocket (the third anchor site, P3) in which they form interactions like COX-2 selective

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inhibitors [7]. At the same time, methyl groups send away the carboxylate groups from Arg 120
and Tyr 355 influence on reducing of hydrophobic interactions and decrease of activity of the
synthesized acids.
Acid 6 (at higher doses), like acid 3 (that shows weak dose dependence), possesses the weakest
anti-inflammatory activity. It has two methyl groups which send away the carboxylate groups from
Arg120 and Tyr 355. Acid 5 possess the strongest anti-inflammatory activity, although it has one
methyl group at the α-position. It could be explained by assuming it occupies the position which
enables the strongest interaction of carboxylate group with Arg 120 (1.94 Ǻ) and with OH group from
acid and N from guanidine group of Arg 120 (3.76 Ǻ), compared to acid 4 (2.06 Ǻ and 5.7 Ǻ) and acid
6 (2.94 Ǻ and 6.66 Ǻ). Also, acid 5 possesses the strongest π→cation interactions with Arg 513
(3.60 Ǻ) compared to acid 4 (3.88 Ǻ) and acid 6 (3.93) (Figure 4).
The best docking poses are illustrated in Figure 5.
Figure 4. Superimposition of most favourable conformations of compounds 4 (blue),
5 (green) and 6 (magenta) docked into binding site of COX-2 receptor [6].

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Figure 5. Anchor sites of COX-2 receptors and best docking poses of compounds
1 (green), 2 (blue), 3 (pink), 4 (gray), 5 (orange) and 6 (purple) [6].
2.4. Statistical analysis
Results were expressed as means ± standard deviations (SD). Statistical analysis was done by the
Mann–Whitney U-test and ANOVA. Differences were accepted as statistically significant when
P < 0.05.
3. Experimental
3.1. Chemistry
In a 100 mL two-necked round bottom flask equipped with CaCl2 tube, argon inlet and magnetic
stirrer, the α-bromopropanoic acid (0.03 mol), ethyl vinyl ether (3.37 g, 5.00 mL, 0.05 mol) and dry
benzene (4–6 mL) were placed and stirred at room temperature for 2 hours. After the evaporation of
benzene and excess of ethyl vinyl ether, the residual mixture was distilled under the reduced pressure.
In this way 4.5 g (0.02 mol) of 1-ethoxyethyl-2-bromopropanoate was obtained.
In 100 mL three-necked, round-bottom flask, equipped with CaCl2 tube, argon inlet and magnetic
stirrer, Zn (0.02 mol, 1.30 g), 4-acetylbiphenyl (0.013 mol, 2.54 g), dried THF (40 mL) and small
amounts of HgCl2 and I2 are placed. Previously prepared ester (0.02 mol, 4.5 g) was added from
dropping funnel during 30 min under the argon atmosphere. The reaction mixture was cooled in ice
bath and constantly stirred magnetically, until whole amount of Zn disappears (3 days). The THF was
removed under reduced pressure, followed by addition of benzene (30 mL) and cold 3 M HCl (10 mL).
This reaction mixture was cooled at 0 °C in ice bath, and stirred for 3 hours. The organic layers were
taken. Obtained aqueous solutions were additionally extracted with benzene. The combined organic
extracts were treated with 10% aqueous KHCO3 until pH 8 was reached the (hydroxyacid was
converted to its potassium salt). The alkaline aqueous solution was extracted by small amount of ether
to remove unreacted ketone. This solution was cooled at 0 °C and cold 10% HCl was carefully added

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to pH 2.5, yielding β-hydroxyacid, as an oil at first, that turned into crystals after prolonged storage at
low temperature. The acid obtained in this way was recrystallized from benzene.
3.2. Animal studies
Adult male Wistar rats, weighing 160–180 g, purchased from the Serbian Military Medical
Academy Animal House were used in the carrageenan-induced rat paw oedema and the gastric
tolerability tests. Experimental groups comprised 6 animals, each. The animals were deprived of food
for 18–20 h before the beginning of experiments, with free access to tap water. All experimental
procedures and protocols conformed to institutional guidelines for care and use of animals in research
No 2/09 (Ethics Committee in research of the Faculty of Pharmacy, Belgrade, Serbia).
3.3. Anti-inflammatory activity: carrageenan-induced rat paw oedema test
The carrageenan-induced rat paw oedema test was used as an experimental model for screening the
anti-inflammatory activity according to the modified method of Oyanagui and Sato [8]. The tested
compounds dissolved in DMSO were administered p.o., throughout the orogastric tube, in doses of
2.5, 5, 10, 15 and 20 mg/kg. ibuprofen (2-[4-(2-methylpropyl)phenyl]propanoic acid), also dissolved in
DMSO, was used as a reference, and given in the same dose-range. The control animals were given
vehicle DMSO in a dose of 1 mL/kg p.o. One hour after the oral administration of the compounds
tested, or ibuprofen, carrageenan-saline solution (0.5%) and saline were injected in a volume of 0.1 mL
into the plantar surface of the right and left hind paw, respectively. Left paw served as the control one
(non-inflamed paw). The animals were sacrificed 3 hours after the carrageenan and saline injection and
paws were cut off for weighing. Difference in weight between right and left paw, active drug-treated
versus vehicle-treated (control) rats, served as an indicator of the anti-inflammatory activity of tested
drugs (compounds and ibuprofen). The anti-inflammatory effect was calculated using the equation:
e
Inflammatory response (%) = ⋅100
(1)
k
where k is a difference in the paw weight in the control group, and e is a difference in the paw weight
in the treated group. On the basis of these results, the corresponding mean effective anti-inflammatory
doses (ED50) were calculated according to the method of Litchfield and Wilcoxon [9].
3.4. Gastric tolerability test
When animals were sacrificed, their stomach were removed and opened along the greater curvature.
Lesions were examined under an illuminated magnifier (3×). The intensity of gastric lesions was
assessed according to a modified scoring system of Adami et al. [10] (0: no lesions; 0.5: slight
hyperaemia or ≤5 petechiae; 1: ≤5 erosions ≤5 mm in length; 1.5: ≤5 erosions ≤5 mm in length and
many petechiae; 2: 6-10 erosions ≤5 mm in length; 2.5: 1-5 erosions >5 mm in length; 3: 5–10 erosions
>5 mm in length; 3.5: >10 erosions >5 mm in length; 4: 1-3 erosions ≤5 mm in length and 0.5–1 mm
in width; 4.5: 4–5 erosions ≤5 mm in length and 0.5–1 mm in width; 5: 1–3 erosions >5 mm in length

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and 0.5–1 mm in width; 6: 4 or 5 grade 5 lesions; 7: ≥6 grade 5 lesions; 8: complete lesion of the
mucosa with haemorrhage).
3.5. Molecular docking experiments
To identify potential anti-inflammatory lead among compounds 1–6, docking calculations were
performed using Autodock v4.0.1 [4] into the 3D structure of the catalytic site of COX-2 enzyme (pdb
code: 1cx2) and COX-1 enzyme (pdb code: 1eqg).
It should be mentioned that the Lamarckian genetic algorithm implemented in Autodock has been
successfully employed to dock inhibitors into the catalytic site of the COX isoenzymes and correlate
the obtained binding free energies with inhibitory activities of the compounds. Briefly, we carried out
comparative docking experiments of synthesized compounds 1–6 with the known non-selective COX
inhibitor ibuprofen. The obtained results were evaluated in terms of binding energy and docking
positioning into the catalytic site of COX-2. Docking calculations predicted the binding conformation
of SC-558 for COX-2 isoenzyme and binding conformation of ibuprofen for COX-1 isoenzyme with a
root main square deviation (RMSD) of 1.44 Δ and 1.48 Δ, respectively, with respect to conformations
from X-ray crystallographic studies [6].
Structures of all possible stereoisomer forms of ligands were generated using the ChemOffice v7.0
Ultra software package and have been MM2 optimized [11]. Each docking experiment consisted of 10
docking runs with 150 individuals and 500,000 energy evaluations. Other parameters were left to their
default values. The search was conducted in a grid of 40 points per dimension and a step size of 0.375
centred on the binding site of enzyme.
4. Conclusions
Molecular docking calculations accompanied by in vivo biological assay were used to identify
potential anti-inflammatory agents among the β-hydroxy-β-arylpropanoic acid class of compounds
acting through a COX-2 inhibition mechanism. The obtained results indicate that all compounds
possess significant anti-inflammatory activity after oral administration and that compound 5 possesses
a strong anti-inflammatory activity, higher than ibuprofen, a standard NSAID. Acids 3 and 6, with two
methyl groups at the α-position possess the weakest anti-inflammatory activity. Tested substances and
ibuprofen did not exhibit any significant gastric lesions. Acids prepared from acetophenone have
exhibited better anti-inflammatory activity than acids prepared from 4-acetylbiphenyl in the
carrageenan-induced rat paw oedema test. It must be stressed-out that compound 4 has
anti-inflammatory activity matching that of ibuprofen, and was proven to be non-toxic towards healthy
cells [4], and is not chiral, which makes it an interesting synthetic drug.
Acknowledgments
This work is supported by Serbian Ministry of Science, Grants No. 172041 and No. 172035.

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Conflicts of Interest
The authors declare no conflicts of interest.
References and Notes
1. Botting, R.M. Cyclooxygenase. Past, Present and Future. J. Therm. Biol. 2006, 31, 208-219.
2. Kiefer, W.; Dannhardt, G. Novel Insights and Therapeutical Applications in the Field of Inhibitors
of COX-2. Curr. Med. Chem. 2004, 11, 3147-3161.
3. Goodsell, D.S. The molecular Perspective: Cyclooxygenase-2. Oncologist 2000, 5, 169-171.
4. Dilber, S.P.; Žižak, Ž.S.; Stojković, T.P.; Juranić, Z.D.; Drakulić, B.J.; Juranić, I.O.;
Antiproliferative activity of β-hydroxy-β-arylalcanoic Acids. Int. J. Mol. Sci. 2007, 8, 214-228.
5. Dilber, S.P.; Dobrić, S.L.; Juranić, Z.D.; Marković, B.D.; Vladimirov, S.M.; Juranić, I.O. Docking
studies and Anti-inflammatory Activity of β-hydroxy-β-arylpropanoic Acids. Molecules 2008, 13,
603-615.
6. Morris, G.M.; Goodsell, D.S.; Halliday, R.S.; Huey, R.; Hart, W.E.; Belew, R.K.; Olson, A.J.
Automated docking using a Lamarckian genetic algorithm and an empirical binding free energy
function. J. Comput. Chem. 1998, 19, 1639.
7. Selinsky, B.S.; Gupta, K.; Sharkey, K.; Loll, P.J. Structural Analysis of NSAID Binding by
Prostaglandin H2 Synthase: Time Dependent and Time-Independent Inhibitors Elicit Identical
Enzyme Conformations. Biochemistry-US 2001, 40, 5172-5180.
8. Oyanagui, Y.; Sato, S. Inhibition by nilvadipine of ischemic and carrageenan paw oedema as well
as of superoxide radical production from neutrophilis and xanthine oxidase. Arzneimittel-Forsch
1991, 41, 5.
9. Litchfield, J.T.; Wilcoxon, F.A. A simplified method of evaluating dose-effect experiments.
J. Pharmacol. Exp. Ther. 1949, 96, 99.
10. Adami, E.; Marazzi-Uberti, E.; Turba, C. Pharmacological research on gefarnate, a new synthetic
isoprenoid with an anti-ulcer action. Arch. Int. Pharmacodyn. Ther. 1964, 147, 113-145.
11. CS ChemOffice Version 7.0 Ultra; Cambridge Soft Corporation, Software Publishers Association:
Washington, DC, USA, 2002.
Sample Availability: Samples of the synthesised compounds are available from the authors.
© 2011 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article
distributed under the terms and conditions of the Creative Commons Attribution license
(http://creativecommons.org/licenses/by/3.0/).