Design, synthesis, docking and anti-inflammatory evaluation of novel series of benzofuran based prodrugs

Article abstract of DOI:10.1016/j.bmcl.2014.03.087

Several new benzofuran derivatives were synthesized, via appropriate synthetic route as anti-inflammatory agents. The anti-inflammatory activity of the prepared compounds was evaluated using carrageenan rat model. Among the synthesized compounds, some compounds showed comparable anti-inflammatory activity to nimesulide, the standard drug taken for anti-inflammatory studies. Docking study of the prepared compounds was performed for the study of interaction of molecules with the active site of COX-2. Preliminary biological studies and docking gave an interesting insight, into the validity of employing benzofuran analogues as good anti-inflammatory agent.

Full text of DOI:10.1016/j.bmcl.2014.03.087

Accepted Manuscript
Design, synthesis, docking and anti-inflammatory evaluation of novel series of
benzofuran based prodrugs
Pratima Yadav, Praveen Singh, Ashish Kumar Tewari
PII:
S0960-894X(14)00323-0
DOI:
http://dx.doi.org/10.1016/j.bmcl.2014.03.087
BMCL 21480
Reference:
Bioorganic & Medicinal Chemistry Letters
To appear in:
Received Date:
Revised Date:
Accepted Date:
21 February 2014
17 March 2014
26 March 2014
Please cite this article as: Yadav, P., Singh, P., Tewari, A.K., Design, synthesis, docking and anti-inflammatory
evaluation of novel series of benzofuran based prodrugs, Bioorganic & Medicinal Chemistry Letters (2014), doi:
http://dx.doi.org/10.1016/j.bmcl.2014.03.087
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers
we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and
review of the resulting proof before it is published in its final form. Please note that during the production process
errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Graphical Abstract
To create your abstract, type over the instructions in the template box below.
Fonts or abstract dimensions should not be changed or altered.
Design, synthesis, docking and anti-
inflammatory evaluation of novel series of
benzofuran based prodrugs
Leave this area blank for abstract info.
Pratima Yadav, Praveen Singh, Ashish Kumar Tewari*

Bioorganic & Medicinal Chemistry Letters
jou rn al h om ep a ge : www .e ls e v ie r .c om
Design, synthesis, docking and anti-inflammatory evaluation of novel series of
benzofuran based prodrugs
Pratima Yadav, Praveen Singh, Ashish Kumar Tewari*
Department of Chemistry, Centre of Advance Studies, Faculty of Science, Banaras Hindu University Varanasi 221 005, India
ARTICLE INFO
ABSTRACT
Article history:
Received
Revised
Accepted
Available online
Several new benzofuran derivatives were synthesized, via appropriate synthetic route as anti-
inflammatory agents. The anti-inflammatory activity of the prepared compounds was evaluated
using carrageenan rat model. Among the synthesized compounds, some compounds showed
comparable anti-inflammatory activity to nimesulide, the standard drug taken for anti-
inflammatory studies. Docking study of the prepared compounds was performed for the study of
interaction of molecules with the active site of COX-2. Preliminary biological studies and
docking gave an interesting insight, into the validity of employing benzofuran analogues as good
anti-inflammatory agent.
Keywords:
Benzofurans;
Inflammation;
Anti-inflammatory;
Drug design;
Molecular modeling;
The use of aspirin for the treatment of inflammation, fever and
pain, dates back to 1897. Since then many non-steroidal anti-
inflammatory drugs (NSAIDs) were developed for the treatment
of inflammation, such as ibuprofen, flurbiprofen, indomethacin
and diclofenac.1 NSAIDs have a wide clinical use for the
treatment of inflammatory and painful conditions including
rheumatoid arthritis, soft tissue lesions, fever and respiratory tract
infections.2 Pharmacological effect of NSAIDs are due to
inhibition of cyclooxygenase (COX), which mediates the
production of prostaglandins, prostacyclins and thromboxanes
from arachidonic acid.3 There are two isoforms, COX-1 and
COX-2. The constitutive COX-1 plays a physiological role in the
kidneys and the stomach, whereas, the COX-2 involved in the
production of prostaglandins mediating pain and supporting the
Consequently, the development of new anti-inflammatory drugs is
still a strong clinical need, especially after the withdrawal of some
selective COX-2 inhibitors such as rofecoxib and valdecoxib.12, 13
In an era where new drug pipelines are drying-up and blockbuster
agents are facing generic competition, the discovery of novel anti-
inflammatory targets continues to propel the development of small
molecule therapeutics to treat inflammatory conditions such as
prodrugs, that temporarily mask the acidic group of NSAIDs thus
reducing or abolishing the GI toxicity due to the local action
mechanism.14Among the many possible prodrugs, bioreversible
esters have received considerable attention because of the presence
of enzymes in the living system capable of hydrolyzing them. By use
of the prodrug approach, one strategy that could be useful is to
temporarily mask the carboxylic acid function of the NSAIDs so that
the prodrug hydrolyzes in vivo to release the active parent NSAID.15-
inflammatory process.4-6
17
Gastrointestinal (GI) erosions and bleeding are two of the most
common toxic side effects associated with the administration of
NSAIDs, which have been observed even with low prophylactic
doses of aspirin (81 mg/day).7 It is estimated that approximately 50%
of patients taking NSAIDs on a long-term basis develop mucosal
damage in the small intestine,8 and 2-4% of these individuals present
clinically significant GI ulcers and bleeding, sometimes leading to
death.9 Side effects is due to high COX-1 versus COX-2 selectivity.
The development of COX-2 selective NSAIDs (coxibs) (Figure1)
was meant to circumvent these side effects, by selectively inhibiting
the isoenzyme involved in the production of pro-inflammatory
mediators. Though clinical trials have shown a reduction of
gastrointestinal and renal side effects, an increase in cardiovascular
(CV) events was observed suggesting that an exclusive inhibition of
COX-2 enzyme could be associated with heart failure and stroke.10, 11
Benzofuran have drawn considerable attention over the last few
years due to their profound physiological and chemotherapeutic
properties as well as their widespread occurrence in
nature.18Benzofuran derivatives are versatile biodynamic agents that
can be used to design and develop new potentially useful therapeutic
agents.19 Natural and synthetic products possessing the 2-
benzylbenzofuran moiety exhibit a broad range of biological and
pharmacological activities such as antimicrobial,20 antioxidant,21
anti-inflammatory,22 antifungal,23 PPARδ agonists,24 antifeedant,
anti-HIV anti-tumor and antiplatelet activities.25
As part of our ongoing research program aimed to develop new
anti-inflammatory agents with a suitable efficacy/safety profile.26-
30we now propose the design and biological evaluation of novel
benzofuran based ester prodrug.
The synthesis of our target compounds were carried out by
adopting a multi-step sequence as outlined in scheme 1. Starting
material p-benzoquinone was synthesized according to
previously reported procedure.31 Subsequently benzofuran
scaffolds were constructed by Michael addition of ethyl
acetoacetate to p-benzoquinone followed by cyclization. Further,
*Corresponding author. Tel.: +919935343986; fax: +915422368127;
e-mail: tashish2002@yahoo.com

benzofuran scaffolds were subjected to O-arylation in basic
condition using CuI catalyst and 8-hydroxyquinoline as co-
catalyst.
(Table 1).
Scheme1. Reagents and conditions: (i) Oxidation, KBrO3; (ii) ZnCl2, (1.2
equiv) toluene, reflux 24h, dean stark apparatus; (iii)K2CO3 (1.0 eq.), CuI
(0.1 eq.), 8-Hydroxyquinoline (0.01eq.)
Table 1. Products and yield of reaction
S. No. Ar
Product
3a
Yield (%)
1.
2.
3.
4.
5.
C6H5
81
78
73
80
74
2-CH3-C6H4
4-CH3-C6H4
4-OCH3-C6H4
3b
3c
3d
Figure 1. Non-steroidal anti-inflammatory drugs (NSAIDs) and coxibs
In preliminary studies with the CuI/NaOH system, the O-
arylation of 5-hydroxybenzofuran with iodobenzene was found to
give no reaction. Rationalizing that could be resistant to
deprotonation; we conducted optimization studies with the same
starting materials as the model substrates (Table 2). After
screening a series of base, 1 eq. of Cs2CO3 was determined to be
the most effective base and gave O-arylated product in 81%
yield. While replacing Cs2CO3 with K2CO3 afforded 3a in a
slightly lower yield of 75%. Increasing the catalyst loading from
5 to 10 mol % was found to improved the product yield. Finally,
on turning our attention to examining solvent effects, we were
pleased to find that DMF as a solvent gave the best result,
furnishing 3a in 81% yield. The yield of the products was
obtained in the range of 60–80%. Designed series of molecules
3e
6.
7.
3f
65
65
3g
8.
9.
10.
11.
C6H5
2-CH3-C6H4
4-CH3-C6H4
4a
4b
4c
4d
69
73
73
74
1
3a–3g, 4a-4e were characterized by IR, H NMR & 13C NMR.
The molecular structure of a representative compound 4b was
confirmed unambiguously by single crystal X-ray diffraction
studies (CCDC 969633) (Figure 2).
12.
4e
60
As prodrug (ester) were rapidly transformed enzymatically to
the parent drug (acid) (Scheme 2) inside body due to presence of
enzymes in the living system capable of hydrolyzing them.32-33
Therefore, we carried out Molecular docking studies of parent
drug (acid) in the active sites of COX-2 in order to get the nature
of interactions between the parent drug (acid) and the active site
amino acids using the docking program Autodock4.2.34The PDB
structure 3LN1 (resolution 2.2Å) was used as a receptor for
docking the molecules. Firstly, all bound water, ligands, and
cofactors were removed from the proteins. The macromolecule
was checked for polar hydrogen; torsion bonds of the inhibitors
were selected and defined. Gasteiger charges were computed and
the AutoDock atom types were defined using AutoDock 4.2,
graphical user interface of AutoDock supplied by MGL Tools.35
Table 2. Optimization of reaction condition
Entry [Cu]source
Solvent
Base
Yield %
0
1.
2.
3.
CuI
CuI
CuI
DMF
DMF
DMF
NaOH
Cs2CO3 81
K2CO3
75
70
4.
5.
6.
7.
8.
9.
10.
11.
CuI
CuI
DMF
DMSO
NMP
m-xylene Cs2CO3 59
DMA
Toluene
Benzene
Dioxane
K3PO4
Cs2CO3 62
Cs2CO3 60
CuI
CuI
CuI
CuI
CuI
CuI
Cs2CO3 53
Cs2CO3 22
Cs2CO3 36
Cs2CO3 28
12.
13.
14.
Cu2O
Cu2O
Cu2O
DMF
DMF
DMF
Cs2CO3 55
K2CO3
K3PO4
47
45
15.
16.
17.
Cu2O
CuCl
CuBr
DMF
DMF
DMF
Cs2CO3 27
Cs2CO3 38
Cs2CO3 41
18.
19.
20.
CuBr2
Cu(OAc)2
Cu(OTf)2
DMF
DMF
DMF
Cs2CO3 39
Cs2CO3 41
Cs2CO3 55
21.
CuSCN
DMF
Cs2CO3 35

Scheme2. Enzymatic transformation prodrug (bioreversible ester) to parent
drug (acid)
The Lamarckian Genetic Algorithm (LGA), which is considered
one of the best docking methods available in AutoDock36-37, was
employed. This algorithm yields superior docking performance
compared to simulated annealing or the simple genetic algorithm
and the other search algorithms available in AutoDock 4.2.
Secondly, the three dimensional grid boxes were created by
AutoGrid algorithm to evaluate the binding energies on the
macromolecule coordinates. Ligand PDB were prepared using
ChemBio3D. The grid maps representing the intact ligand in the
actual docking target site were calculated with AutoGrid (part of
the AutoDock package). Eventually cubic grids encompassed the
binding site where the intact ligand was embedded. Finally,
AutoDock was used to calculate the binding free energy of a
given inhibitor conformation in the macromolecular structure
while the probable structure inaccuracies were ignored in the
calculations. The search was extended over the whole receptor
protein used as blind docking. Nimesulide (Native Ligand) in the
crystal structure was docked as reference. The binding mode of
the most active parent drug (acid) 5c to the COX-2 protein
and main interactions are shown in (Figure 3). The benzofuran
ring of the of compound 5c is placed close to the side chain of
Gln431 to form hydrogen bond at distances of 2.092 Å. Table 3
shows the docking scores of the active parent drug molecules
within the active site of COX-2.
Figure 3. Interactions of compound 5c in the active site of COX-2 Green
lines indicate H-bonds formed between the compound and the enzyme active
site residues.
Anti-inflammatory study of compounds was performed in order
to rationalize the obtained docking results. All the newly
synthesized compounds and nimesulide, as a reference drug,
were subjected to in vivo anti-inflammatory study using the well-
known rat carrageenan induced foot paw edema model.38The
results of anti-inflammatory activity against carrageenan induced
rat paw edema model were shown in Table 4, and Table 5.The
results of present study have shown that compounds 3b, 3d had
shown to possess maximum inhibitory effect when compared to
control group. It was observed that maximum percentage of paw
edema growth in control group at 90 min. was 38.7 % which was
found to decrease up to 20.4, 12.3 % in the group of rats treated
with 3b, 3d respectively, compared to nimesulide treated group
where it was found 23.4 % also, the values were found
statistically very significant. 3c, 3e have also been found to
possess very good anti-inflammatory property as the percentage
paw edema growth was shown to be only 25.8, 18.9 % when
compared to that of control group (where it was 38.7 % at 90
min.). Compound 4b show intermediate effect, while compound
4c, and 4d show negligible effect. (Figure 4) As shown in Table
5. Compound 3b & 3d show maximum inhibitory effect, while
compound 3c & 4a-d to show intermediate effect. Thus a
comparison of the SAR data showed that series 3a-d more potent
inhibitor of inflammation relative to 4a-4e due to electron
donating methyl group.
Table 4. Percentage Edema Growth Relative to Control at
Different Time Intervals (Mean+S.E.M.)
Group
0 min 30min
90min
Control
100 0 130.1 6.54 (30.1) 138.7 4.47 (38.7)
Figure 2. ORTEP plot of the X-ray crystal structure of 4b Displacement
Nimesulide 100 0 114.1 2.88 (14.1) 123.4 3.27(23.4)*
ellipsoids are drawn at the 30% probability level
3a
3b
3c
3d
4a
4b
4c
4d
100 0 115.7 3.31 (15.7) 123.8 7.12(23.8) *
100 0 110.1 5.14 (10.1) 120.4 3.17(20.4)*
100 0 114.1 2.88 (14.1) 125.8 8.42(25.8)*
100 0 109.5 2.68 (9.5) 112.3 7.77(12.3)*
100 0 115.8 4.19 (15.8) 128.4 4.78(28.4)*
100 0 114.8 4.03 (14.8) 124.4 6.78(24.4)*
100 0 122.1 5.11 (22.1) 132.6 3.13(32.6)*
100 0 125.1 5.11 (25.1) 132.6 3.13(32.6)*
Table 3. Dock scores and summary of molecular interactions of
compounds after docking into COX-2 active site
Entry
Dock score Summary of interactions
Nimesulide -12.09
Arg120, Tyr355, Ser530
Leu138, Cys21
Val 335, Ala 513
5a
5b
5c
-6.00
-6.87
-6.68
Pro139, Pro140,Cys21,Gly121
4e
100 0 120.1 5.11 (20.1) 132.6 3.13(32.6)*
5d
5e
5f
6a
6b
6c
6d
6e
-6.52
-6.11
-7.07
-7.28
-7.49
-7.62
-7.29
-7.30
Ala 188, His193, Thr 192
Leu138, Arg455
Cys32, Leu138, Cys 32
Lys68, Cys21,Arg 120
Leu138, Pro139, Arg 455, Glu 451
Cys32, Gly 30
N=number of rats in each group. Results in parentheses indicate percentage
change from respective control group. *p-value<0.05
All the synthesized compounds were evaluated for their anti-
inflammatory activity by biochemical COX (COX-1 & COX-2)
inhibitory assay. The ratio of IC50 of COX-2 to IC50 of COX-1
(COX- 2/COX-1) would suggest the selectivity of the compound
and hence its gastric liability (Table 6).39-41 All prepared
Arg 455, Cys32
Thr61, Phe49, Tyr108

compounds showed weaker COX-2 inhibitory potency and
selectivity compared to celecoxib. Among them compounds 3b,
3c, 3d, and 3e were proved to be potent COX-2 inhibitors with
IC50 range of 4.2-8.6 µM compare to compound 4a-c.
interaction increase the residence time of ligand in the active site
consequently augmenting anti-inflammatory activity of
compounds.
Acknowledgments
Table 5. Paw Edema at Different
Time
Interval
(ml/Rat)(Mean+S.E.M.)
Authors acknowledge UGC (Grant Sanction No. 37-54/2009)
India for financial assistance of the work. Department of
Chemistry, Banaras Hindu University, Varanasi, INDIA is
acknowledged for departmental facilities.
Entry
0 min
30min
90min
1.36 0.070
Control
0.99 0.067 1.27 0.043
Nimesulide 1.02 0.054 1.16 0.065
1.26 0.038
1.46 0.068
0.98 0.044
1.11 0.045
1.39 0.068
1.38 0.058
1.31 0.061
1.29 0.061
1.31 0.066
0.98 0.044
3a
3b
3c
3d
4a
4b
4c
4d
4e
0.78 0.033 0.89 0.041
0.78 0.033 0.89 0.041
0.98 0.031 1.06 0.038
0.76 0.054 1.29 0.061
1.08 0.038 1.25 0.054
1.06 0.044 1.21 0.058
0.98 0.053 1.19 0.058
0.96 0.044 1.21 0.078
0.75 0.083 0.89 0.061
References and notes
1.
2.
Vane, J. R. Nat. New Biol. 1971, 231, 232.
Sorbera, L.A.; Lesson, P.A.; Castanar, J.; Castanar, R.M. Drugs Future.
2001, 26, 133.
3.
4.
Eleftheriou, P.; Geronikaki, A.; Hadjipavlou-Litina, D., Vicini, P.; Filz,
O.; Filimonov, D., Poroikov, V.; Chaudhaery, S. S.; Roy, K. K.;
Saxena. A. K. Eur. J. Med. Chem. 2012, 47, 111.
Kujubu, D. A.; Fletcher, B. S.; Varnum, B. C.; Lim, R. W.; Herschman,
H. R. J. Biol. Chem. 1991, 266, 12866.
5.
6.
Crofford, L. J. J. Rheumatol.1997, 24 (Suppl. 49), 15.
Seibert, K.; Zhang, Y.; Leahy, K.; Hauser, S.; Masferrer, J.; Perkins,
W.; Lee, L.; Isakson, P. Proc. Natl. Acad. Sci. U.S.A. 1994,91, 2013.
Yeomans, N.; Hawkey, C.; Brailsford, W; Naesdal, J. Curr. Med.
Res.Opin. 2009, 25, 2785.
Higuchi, K.; Umegaki, E.; Watanabe, T.; Yoda, Y.; Morita, E.; Murano,
M.; Tokioka, S.; Arakawa, T. J. Gastroenterol. 2009, 44, 879.
Wolfe, M.; Lichtenstein, D.; Singh, G. New Engl. J. Med. 1999, 340,
1888.
7.
8.
9.
10. Scheen, A. J. Rev. Med. Liege. 2004, 59, 565.
11. Dogne, J. M.; Supuran, C. T.; Pratico D. J. Med. Chem. 2005, 48, 2251.
12. Hayta, S.; Arisoy, M.; Arpaci, O.; Yildiz, I.; Aki, E.; Zkan, S.; Kaynak
F. Eur. J. Med. Chem. 2008, 43, 2568.
13. Kamal, M.; Shakya, A. K.; Jawaid, T. Int. J. Med. Pharm. Sci. 2011, 1,
1.
14. Bandgar, B.; Sarangdhar, R.; Viswakarma, S.; Ahamed, F. J. Med.
Chem. 2011, 54, 1191.
15. Wallace, J. J. Physiol. Pharmacol. 1994, 72, 1493.
16. Kim, H.; Jeon, H.; Kong, H.; Yang, Y.; Choi, B.; Kim, Y.; Neckers, L.;
Jung, Y. Mol. Pharmacol. 2006, 69, 1405.
17. Gairola, N.; Nagpal, D.; Dhaneshwar, S; Chaturvedi, S. Indian J.
Pharm. Sci. 2005, 67, 369.
18. Hayta, S. A.; Arisoy, M.; Arpaci, O. T.; Aki, I. Y. E.; Zkan, S.; Kaynak,
F. Eur. J. Med. Chem. 2008, 43, 2568.
19. Kamal, M.; Shakya, A. K.; Jawaid, T. Int. J. Med. Pharm. Sci. 2011, 1,
Figure 4. Effect of different drugs on carrageenan induced rat pawedema
1.
20. Liu, J.; Jiang, F.; Jiang, X.; Zhang, W.; Liu, J.; Liu, W.; Fu L. Eur. J.
Med. Chem. 2012, 54, 879.
21. Rangaswamy, J.; Kumar, H. V.; Harini, S. T.; Naik, N. Bioorg. Med.
Chem. Lett. 2012, 22, 4773.
22. Hassan, G. S.; Abou-Seri, S. M.; Kamel, G.; Ali, M. M. Eur. J. Med.
Chem. 2014, 76, 482.
23. Telvekar, V. N.; Belubbi, A.; Bairwa, V. K.; Satardekar, K.; Bioorg.
Med. Chem. Lett. 2012, 22, 2343.
24. Filzen, G. F.; Bratton, L.; Cheng, X. M.; Erasga, N.; Geyer, A.; Lee, C.;
Lu, G.; Pulaski, J.; Sorenson, R. J.; Unangst, P. C.; Trivedi, B. K.; Xu
X. Bioorg. Med. Chem. Lett. 2007, 13, 3630.
25. Song, W. J.; Yang, X. D.; Zeng, X. H.; Xu, X. L.; Zhang, G. L.; Zhang,
H. B. RSC Adv. 2012, 2, 4612.
Table 6. Cox-2/Cox-1 enzyme inhibition assay of Benzofuran
derivatives.
Compound
Cox -1
IC50 (µM)a
15
Cox-2
IC50 (µM)a
0.04
18.5
6.1
4.2
8.6
8.1
15.8
18.2
20.1
19.2
SIb
Celecoxib
0.0028
0.5900
0.1700
0.0800
0.2300
0.2900
0.3500
0.4300
0.6700
0.7400
3a
3b
3c
3d
3e
3f
30.8
35.8
49.7
38.1
27.9
47.5
42.5
29.8
26. Tewari, A. K. Srivastava P. Singh V. P. Singh A. Goel R. K. Mohan C.
4a
4b
4c
G. Chem. Pharm. Bull. 2010, 58, 634.
27. Tewari, A. K.; Mishra, A. Bioorg. Med. Chem. 2001, 9, 715.
28. Srivastava, P.; Singh, P.; Tewari, A. K. Med. Chem. Res. 2011, 44,
9774.
29. Tewari, A. K.; Dubey, R.; Mishra, A. Med. Chem. Res. 2011, 20, 125.
30. Dubey, R.; Singh, P.; Singh, A. K.; Yadav, M. K.; Swati, D.; Vinayak,
M., Puerta, C.; Valerga, P.; Kumar, R.; Sridhar, B.; Tewari, A. K. Cryst.
Growth Des. 2014, dx.doi.org/10.1021/cg401842y
31. Hendrickson, J. E.; Cram, D. J.; Hammond, G. S. Organic Chemistry,
McGraw Hill: New York, 1970, 3rd Edition.
32. Ettmayer, P.; Amidon, G. L.; Clement, B.; Testa, B. J. Med. Chem.
2004, 47, 2393.
33. Ettmayer, P.; Amidon, G. L.; Gardner, I.; Dack, K. Curr. Drug Metab.
2003, 4. 461.
26.2
a IC50 value is the compound concentration required to produce 50%
inhibition of COX-1or COX-2 for means of two determinations.
b Selectivity index (COX-2 IC50/COX-1 IC50
)
A series of novel benzofurans analogues were synthesized and
their anti-inflammatory activity was determined using
carrageenan mouse paw edema bioassay. In synthesized
compounds, 3c exhibited good anti-inflammatory activity, and
optimal COX-2 inhibitory potency (IC50 = 4.2 µM). Molecular
modeling showed that benzofurans analogues interact with COX-
2 active site by forming classical hydrogen bonding and this

34. Autodock tools (ADT) program, Molecular Graphics Laboratory, the
ScrippsResearch Institute. http://autodock.scripps.edu/
35. Sanner, M. F. J. Mol. Graph. Model. 1999, 28, 57.
36. Huey, R.; Morris, G. M.; Olson, A. J.; Goodsell, D. S. J. Comput.
Chem. 2007, 28, 1145.
37. Morris, G. M.; Goodsell, D. S.; Halliday, R. S.; Huey, R.; Hart, W. E.;
Belew, R. K.; Olson, A. J. J. Comput. Chem. 1998, 17, 1639.
38. Winter, C. A.; Risely, E. A.; Nuss, G. W. Proc. Soc. Exp. Biol. 1962,
111, 544.
39. Copeland, R. A.; Williams, J. M.; Giannaras, S.; Nurnberg, M.;
Covington, D.; Pinto, S.; Pick, J. M. Proc. Natl. Acad. Sci. USA. 1994,
23, 11202.
40. Pagels, W. R.; Sachs, R. J.; Marnett, L. J.; Dewitt, D. L.; Smith. W. L.
J. Biol. Chem. 1983, 258, 6517.
41. Egan, R. W.; Paxton F. A. J. Biol. Chem. 1976, 251, 7329.