The introduction of P4 substituted 1-methylcyclohexyl groups into Boceprevir: A change in direction in the search for a second generation HCV NS3 protease inhibitor

Article abstract of DOI:10.1016/j.bmcl.2010.02.063

In the search for a second generation HCV protease inhibitor, molecular modeling studies of the X-ray crystal structure of Boceprevir 1 bound to the NS3 protein suggest that expansion into the S4 pocket could provide additional hydrophobic Van der Waals interactions. Effective replacement of the P4 tert-butyl with a cyclohexylmethyl ligand led to inhibitor 2 with improved enzyme and replicon activities. Subsequent modeling and SAR studies led to the pyridine 38 and sulfone analogues 52 and 53 with vastly improved PK parameters in monkeys, forming a new foundation for further exploration.

Full text of DOI:10.1016/j.bmcl.2010.02.063

Bioorganic & Medicinal Chemistry Letters 20 (2010) 2617–2621
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
The introduction of P4 substituted 1-methylcyclohexyl groups into
BoceprevirÒ: A change in direction in the search for a second generation
HCV NS3 protease inhibitor
*
Frank Bennett , Yuhua Huang, Siska Hendrata, Raymond Lovey, Stephane L. Bogen, Weidong Pan,
Zhuyan Guo, Andrew Prongay, Kevin X. Chen, Ashok Arasappan, Srikanth Venkatraman,
Francisco Velazquez, Latha Nair, Mousumi Sannigrahi, Xiao Tong, John Pichardo, Kuo-Chi Cheng,
Viyyoor M. Girijavallabhan, Anil K. Saksena, F. George Njoroge
Schering-Plough Research Institute, 2015 Galloping Hill Road, K-15-A-3545, Kenilworth, NJ 07033, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
In the search for a second generation HCV protease inhibitor, molecular modeling studies of the X-ray
crystal structure of BoceprevirÒ 1 bound to the NS3 protein suggest that expansion into the S4 pocket
could provide additional hydrophobic Van der Waals interactions. Effective replacement of the P4 tert-
butyl with a cyclohexylmethyl ligand led to inhibitor 2 with improved enzyme and replicon activities.
Subsequent modeling and SAR studies led to the pyridine 38 and sulfone analogues 52 and 53 with vastly
improved PK parameters in monkeys, forming a new foundation for further exploration.
Ó 2010 Elsevier Ltd. All rights reserved.
Received 3 November 2009
Revised 11 February 2010
Accepted 16 February 2010
Available online 19 February 2010
Hepatitis C virus (HCV) infection is a principle cause of chronic
liver disease that leading to fibrosis, cirrhosis and/or hepatocellular
carcinoma in humans.1 HCV has infected more than 170 million
people worldwide and it has emerged as a major global health
and BoceprevirÒ (SCH 503034)9 from Schering-Plough. Both are
currently in late stage (phase III) clinical trials.
Our first generation HCV NS3 protease inhibitor, compound 1
(BoceprevirÒ, Fig. 1), is a potent inhibitor of the NS3 protease with
*
problem. Currently available therapy is
a-interferon, either alone
a enzyme assay (Ki ) of 14 nM and a cell-based assay EC90 of
or in combination with ribavirin. The latest combination therapy
with peginterferon and ribavirin generates sustained virological
response in only 40% of infected genotype 1 patients.2 Sustained
response rates of 80-90% are reported in genotype 2 and 3 individ-
uals,3 While results are achieved, existing therapies are associated
with considerable side effects demonstrating a need to develop
more effective antiviral agents. This has stimulated intensive re-
search in finding potent and orally bioavailable small molecule
drug candidates.4
The HCV viral RNA genome encodes a polyprotein which con-
sists of structural and nonstructural (NS) proteins. The chymotryp-
sin-like serine protease is located in the N-terminal of NS3
nonstructural protein and is essential for viral replication.5 It has
been a valuable target for which a number of inhibitors have been
reported in literature.6 several drug candidates have or are being
progressed into clinical trials in human beings. The earliest entry,
BILN-2061,7 an NS3 protease inhibitor from Boehringer–Ingelheim,
was halted in phase I clinical trials due to toxicity. Currently, the
most advanced candidates are Teleprivir (VX-950)8 from VertexÒ
350 nM.8 It had favorable pharmacokinetic (PK) profiles in rats
and dogs (26% and 34% bioavailability, respectively) but low
P2
P'
NH2
P4
O
H
N
O
H
N
NH2
N
H
H
N
N
H
N
H
N
O
O
N
O
O
O
O
O
O
P1
P3
2
1
Boceprevir (SCH 503034)
Ki* = 8 nM
Ki* = 14 nM
EC90 = 350 nM
EC90 = 200 nM
HNE/HCV=4,100
HNE/HCV=2,200
Rat bioavail.26 %
Monkey bioavail. 4-11%
Dog bioavail. 30 %
* Corresponding author. Tel.: +1 908 740 3103; fax: +1 908 740 7152.
E-mail address: frank.bennett@spcorp.com (F. Bennett).
Figure 1. BoceprevirÒ 1: the HCV protease inhibitor that is in phase III clinical
trials. and its 1-methylcyclohexyl analogue 2.
0960-894X/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2010.02.063

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F. Bennett et al. / Bioorg. Med. Chem. Lett. 20 (2010) 2617–2621
bioavailability in monkeys (4–11%). In the clinic it was shown to be
efficacious and well tolerated. Phase II trials have been completed
and phase III studies have been initiated. Our goal for a next gen-
eration inhibitor was to develop more potent inhibitors with im-
proved upon PK profile, particularly in monkeys, to target a once
a day compound.
BoceprevirÒ 1, and the compounds reported in this work were
examined in a HCV protease continuous assay10 using the NS4A-
tethered single chain NS3 serine protease.11 The Ki values deter-
*
mined in the experiments are a reflection of the equilibrium
constant determined by the reversible covalent bond formed be-
tweentheelectrophilic ketoneof theinhibitorand theactivesiteser-
ine residue and other interactions formed between the interacting
species.12 Active compounds were then evaluated in a replicon-
based cell assay.13 The EC90 was determined as the concentration
of inhibitor required for 90% inhibition of viral replication. All com-
pounds were isolated and tested as a mixture of diastereomers with
respect tothe epimerizable P1center. Theinhibitorswerealso tested
against the serine protease, human neutrophil elastase (HNE), a clo-
selyrelatedenzyme, andtheratioofactivityHNE/HCVwastakenasa
measure of selectivity.
Figure 2. X-ray structure of compound 2 bound to the active site of HCV NS3/NS4A
protease domain.
Modeling studies based on X-ray crystal structure of compound
1 revealed that the urea nitrogens donated two H-bonds with the
carbonyl oxygen of alanine-157 and while the tert-butyl group
occupied the S-4 pocket there was an opportunity for expansion
in this cavity. To test this hypothesis we synthesized compounds
2 (Fig. 1) and the cyclopropyl analogues 3–8 (Table 1) and slight
improvements in both enzyme and cell based potencies were
observed.
As can be seen from Table 1, there was no significant change in
potency with respect to P4 ring size, all four compounds (3–6) dis-
playing enzyme and replicon potencies in line with the P1 cyclobu-
tyl analogue 2. The only noticeable advantage may lie with the
elastase selectivity of the six-membered ring analogue 5.
The X-ray structure of 2 bound to the enzyme revealed that in
addition to the interactions observed with the clinical candidate
1, the cyclohexyl group was nestled in the S4 pocket on one side
and the other side was solvent exposed.14 The methyl group of
the P4 ligand clearly extended into the solvent in the direction of
Cys159 of the protein backbone suggesting opportunities for addi-
tional interactions (Fig. 2).
Early attempts to further improve the physical parameters of
our inhibitors involved introducing hydrophilic functionality into
the methyl group of the P4 ligand. Using the P1 cyclopropylmethyl
side chain, derived from commercially available racemic cyclopro-
pylalanine, the alcohol analogue 7 and amine analogue 8 are pre-
pared (Fig. 3). Unfortunately, the amine 8 proved to be relatively
inactive and the alcohol 7, while active in the enzyme assay, was
not potent in the replicon assay, a possible indication of poor cell
penetration.
O
O
H
N
H
N
NH2
NH2
N
N
HO
H
N
H
N
H2N
H
N
H
N
O
O
O
O
O
O
O
O
8
7
Ki* = 140 nM
Ki* = 15 nM
EC90 = > 1,000 nM
Figure 3. 1-Hydroxymethylcyclohexyl 7 1-aminomethylcyclopentyl 8 analogues.
At this stage we realized that to achieve optimal interactions
between substrate and protein we would have to replace the
methyl group in the P4 ligands shown above with a more substan-
tial template. To this end we prepared the phenyl 9, benzyl 10 and
sulfone 11 analogues (Fig. 4). Replacement of the terminal phenyl
groups in 10 and 11 with alternative suitably substituted aromatic
groups such as pyridyl, furyl and phenols which could become
hydrogen bond donors or acceptors with the protein back-bone
O
O
H
N
H
N
NH2
NH2
N
N
H
N
H
N
H
N
H
N
O
O
O
O
O
O
O
O
9
10
Ki* = 47 nM
EC90 = 400 nM
HNE/HCV=320
Ki* = 12 nM
Table 1
EC90 = 85 nM
Attempted optimization of P4 cycloalkyl ring size the S4 pocket of HCV protease
HNE/HCV=395
O
H
O
H
N
NH2
N
NH2
N
N
H
H
N
H
N
H
N
O
O
O
O
N
S
O
O
O
O
O
O
n
11
Ki* = 3 nM
EC90 = 100 nM
HNE/HCV=390
*
Compound
n
Ki (nM)
HNE/ HCV
EC90 (nM)
3
4
5
6
0
1
2
3
24
10
16
15
110
300
640
155
200
200
250
250
Figure 4. 1-Phenylcyclopentyl 9, 1-benylcyclohexyl 10 and phenylsulfone 11
analogues.

F. Bennett et al. / Bioorg. Med. Chem. Lett. 20 (2010) 2617–2621
2619
and/or impart physical properties conducive to improved PK
parameters. Furthermore, functionality could also be introduced
into the benzylic position of compound 10, providing additional
opportunities for interaction with the protein back-bone.
transformation to the isocyanate and incorporation into the target
compound via addition to hydrochloride salt 17 followed by oxida-
tion. The P4 ligand found in inhibitor 9 was obtained directly from
commercially available 1-phenyl-1carboxylic acid. However, as the
ring size study with the methyl analogues (3–6; Table 1) provided
a somewhat flat SAR, we decided to reinvestigate these structural
changes with respect to the benzyl analogue 10 before conducting
further modifications. The results derived from the respective
cyclopentyl 23 and cycloheptyl 24 analogues are shown in Figure
5. Both five- and seven-membered ring (23, 24, respectively) ana-
logues were clearly less active than the cyclohexyl derivative 10 in
both the enzyme and cell based assays.
The syntheses of the compounds in this work, exemplified
through the construction of the amine 8 and sulfone 11, are out-
lined in Scheme 1, beginning with the appropriate cycloalkylcarb-
oxylic methyl ester. Treatment of the anion generated from
commercially available methyl cyclopentanecarboxylate methyles-
ter 12 with chloromethyl benzyl ether produced the benzyl ether
13 which is subsequently converted to the alcohol 14 under hydro-
genation conditions. Mesylation and displacement with sodium
azide gave the methyl ester 15 which was hydrolyzed to the corre-
sponding carboxylic acid. Curtius rearrangement provided the
isocyanate 16, which is exposed to the previously described
hydrochloride salt 179 in the presence of triethylamine to the
Based on the results in Figure 5, we decided to keep the six-
membered ring a constant and a series of analogues based on com-
pound 10 is shown in Table 2.
Using the benzyl analogue 10 as a bench-mark in this study we
observed that when functionality was introduced at the benzylic
position in the P4 residue that although enzyme activity was
retained and selectivity against HNE was vastly improved, it was
detrimental to the relatively more important replicon assay. The
methyl 25, ethyl (26) and hydroxy (27) substituted derivatives
were less active than the parent 10 by more than a factor of four
in the cell based analysis while the ketone 28 by a factor of more
than 20. The naphthyl derivatives 29 and 30 were clearly less ac-
tive in both enzyme and cell based studies and as a consequence
were no further interest. Of more interest, the phenol analogues
(31–33) displaying an interesting SAR pattern. While, the 4-hydro-
xy 33 analogue proved to be obviously less active, the ortho-31 and
meta-substituted 32 derivatives displayed excellent potency com-
parable to the parent compound 10. Similarly, the thiophenes (34
and 35), furan 36, thiazole 37 and 2-pyridyl derivative 38 all dis-
played similar activities and were in line with the benzyl derivative
10. The isomeric pyridyls 39 and 40 were observed to be less
potent.
intermediate
a-hydroxy amide was subsequently oxidized to the
corresponding ketone 18, under Pfitzner–Moffat conditions. Final-
ly, reduction of the azide under hydrogenation conditions provided
the target amine 8. The synthesis of the sulfone 11 was obtained in
a similar manner. Mesylation of the alcohol 19 followed by dis-
placement with sodium thiophenoxide and hydrolysis of the
methyl ester provides the sulfide-carboxylic acid 20. Oxidation
with oxone generates the sulfone 21. Curtius rearrangement and
exposure of the resulting isocyanate 22 with 17 in the presence
of triethylamine provided the intermediate
which is finally oxidized to the target 11.
All other compounds described in this Letter were prepared
from variations of the chemistry described in Scheme 1. For exam-
ple, the benzyl analogue 10 was obtained from the benzylation of
the anion generated from cyclohexanecarboxylate methylester,
a-hydroxyamide
CO2Me
CO2Me
HO
Inhibitors that displayed interesting biological activities were
subsequently analyzed for their PK properties by the oral route in
rats while exceptionally important analogues were also studied in
CO2Me
BnO
a
c,d
b
+
14
12
13
monkeys. For example, the methyl analogues 4 (AUC = 0.21
1% bioavailability) and 5 (AUC = 0.11 M h; 1% bioavailability) when
administered at 10 mpk by the oral route in rats. Similarly the potent
phenol analogue 32 (AUC = 0.09 M h) and the thiophene 35
(AUC = 0.23 M h; 4% bioavailability) provided equally disappoint-
ing results. Interestingly, the more biologically active pyridine 38
generated more encouraging results (AUC = 0.56 M h; 7%
lM h;
l
OH
O
H
N
NH2
l
N
N3
N=C=O
HCl.H2N
O
CO2Me
N3
l
e,f
O
b
l
17
16
15
bioavailability) possibly providing evidence that by changing the
physical properties of these inhibitors as a result of modifying the
terminal aromatic group in the P4 ligands could improve serum
concentrations following oral administration in this class of com-
pound. This phenomenon became more evident when these mole-
cules were administered to monkeys. For example, the compound
38 that provided the most encouraging results in rats delivered
O
H
N
NH2
g,h
N
8
H
N
H
N
O
O
N3
O
O
18
excellent serum concentrations in monkeys (AUC = 16.4 lM h) after
oral administration at 3 mpk, while other potent derivatives such as
CO2H
CO2H
CO2Me
HO
c, i, e
j
S
O
S
O
21
O
20
N=C=O
O
H
N
19
H
N
NH2
NH2
N
N
H
N
H
N
H
N
H
N
O
O
O
O
g,h
f
O
O
11
+
17
S
O
O
O
O
24
23
22
Ki* = 78 nM
Ki* = 24 nM
EC90 = 700nM
HNE/HCV=73
EC90 = 300 nM
HNE/HCV=130
Scheme 1. Reagents and conditions: (a) KHMDS, BOMCl, THF; (b) H2, Pd–C, EtOH;
(c) MsCl, Et3N, CH2Cl2; (d) NaN2, DMF, reflux; (e) KOH, MeOH; (f) Ph2P(O)N3, Et3N,
toluene, 110 °C; (g) Et3N, CH2Cl2; (h) Cl2CCO2H, EDCI, DMSO, toluene; (i) NaSPh,
EtOH; (j) oxone, H2O/MeOH.
Figure 5. Cyclopentyl 23, and cycloheptyl 24 analogues of 10

2620
F. Bennett et al. / Bioorg. Med. Chem. Lett. 20 (2010) 2617–2621
Table 2
Table 3
P4 1-Benzylcyclohexyl analogues of BoceprevirÒ
Sulfone analogues of BoceprevirÒ
O
O
H
N
H
N
NH2
NH2
N
N
H
N
H
N
H
N
H
N
R
O
O
R
O
O
O
O
R1
O
O
*
*
Ki (nM) HNE HCV EC90 (nM)
Compound
R
Ki (nM)
HNE/HCV
395
EC90 (nM)
85
Compound P3 Cap
R1
O
O
10
12
S
11
41
42
43
3
9
570
1100
1566
200
100
200
25
26
11
20
2600
1500
400
400
O O
S
O O
S
10
6
300
N
27
11
1171
400
O
O
OH
S
HO
1000
28
29
100
44
230
470
2000
400
O O
S
O
44
45
10
4
260
200
400
500
O
O
O
O
S
30
31
300
19
O
O
46
47
48
49
50
51
52
5
2
90
460
400
300
500
400
90
S
OH
440
455
260
150
70
O
O
OH
S
32
33
9
O
O
S
4
2400
290
HO
30
400
O
O
11
5
S
34
35
36
9
10
11
470
280
440
200
100
100
S
S
O
O
O
O
S
1200
110
O
S
12
3
100
80
O
N
O
37
38
39
40
11
7
620
310
200
250
200
180
400
300
S
S
730
N
N
25
39
surprisingly, as in previous studies,10 the introduction of this rela-
tively larger ligand provided an improvement in elastase selectiv-
ity. The pyridyl derivative 42 although equally potent in the
enzyme assay with its phenyl counterpart 41, provided a further
drop in cell based activity. Reverting back to cyclopropylalanine
at P1, a number heteroaromatic groups were introduced into the
sulfone P4 ligand. The phenol 43, the furans 44 and 45 and benzyl
derivatives 46, although potent in the enzyme assay provided dis-
appointing cell based potency (EC90 = 400–1000 nM), Partly based
on these results and for the sake of completeness we decided to
examine the effect of replacing these aromatic moieties with sim-
ple alkyl groups (entries 47–52). As with the aromatic derivatives
the major distinguishing feature became the cell based replicon
activity. Although initial results from analogues 48–50 were disap-
pointing, we quickly observed that by introducing cyclobutylala-
nine in the P1 position improvements in cell based potency could
be achieved by introducing minor modifications to the P4 alkyl
group. For example, ethyl analogue 50 displayed excellent enzyme
(IC50 = 5 nM) and cell based (EC90 = 90 nM) activities, as well as
excellent enzyme selectivity (HNE/HCV = 1200). This encouraging
N
thethiophene(35), thefuran(36)andthephenol(32)analoguespro-
vided extremely disappointing PK results (AUC <0.2 M h).
l
Concurrent with the aforegoing study, we investigated the
influence of compounds containing P4 ligands with similar aro-
matic groups linked through a sulfone (e.g., compound 11; Fig. 4)
would have on potency and subsequently PK properties. In addi-
tion to the variables presented to the previous study, we investi-
gated the effects of substituting of cyclopropylalanine at P1 in
the inhibitors with the analogous cyclobutyl ligand, the residue
present in our clinical candidate 1. The results from this study
are displayed in Table 3.
Using the phenyl sulfone 11 as the standard, we can see that by
introducing cyclobutylalanine at P1, resulting in compound 41, a
loss in both enzyme and cell based potencies were observed. Not

F. Bennett et al. / Bioorg. Med. Chem. Lett. 20 (2010) 2617–2621
2621
result prompted us to prepare the tert-butyl derivatives 51 and 52
and we were particularly pleased to see that in addition to having
acceptable enzyme potency and selectivity, both analogues dis-
played excellent cell based activity (EC90 = 100 and 80 nM,
respectively).
As in the previous study, inhibitors that displayed interesting
biological activity were examined for their PK properties in rats
and monkeys. Unfortunately, the phenyl sulfone analogue 11 and
the tert-butyl sulfone derivatives 51 and 52 provided disappointing
exposure in rat could be vastly improved through the introduction
of a P10 ligand such as an allyl group,9 (e.g., 53 vs 54 in Fig. 6), we
believed that secondary
a-ketoamides with the sulfone capping
group could provide us with compounds with acceptable rat PK.
The improvement of monkey PK provides an opportunity for
assessment of additional compounds.
The results of the investigation of the introduction of P10 ligands
into compounds such as 38, 51 and 52 will be reported in a sepa-
rate publication.
results in rat PK (AUC = 0.01, 0.05 and 0.07
tively). Although the monkey PK for phenyl sulfone 11 was also
poor (AUC = 0 M h at 3 mpk), the tert-butyl sulfone inhibitor 51
displayed surprisingly good exposure (AUC = 4.0 M h at 3 mpk).
The P1 cyclobutylalanine analogue 52 provided equally impressive
monkey PK (AUC = 3.2 M h at 3 mpk).
lM h at 10 mpk, respec-
References and notes
l
l
1. (a) Cohen, J. Science 1999, 285, 26; (b) Alter, M. J.; Kruszon-Moran, D.; Nainan,
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Engl. J. Med. 1999, 341, 556; (c) Cuthbert, J. A. Clin. Microbiol. Rev. 1994, 7,
505.
l
In summary, in the search for a second generation protease
inhibitor with improved PK parameters, guided by X-ray structure
of the inhibitor bound to the NS3 protease, we explored the exten-
sion of the P3 capping group into the S4 pocket. Expansion of the
tert-butyl group led to a series of cycloalkyl analogues (2–6) with
improved cell based replicon activities. Subsequent X-ray structure
of one of these derivatives with the protein suggested further mod-
ifications which prompted the development of two series of inhib-
itors (Tables 2 and 3). The three leading compounds (38, 51 and 52)
from this study are listed in Table 4. They had improved potency in
replicon assay (2–4-fold). Further, PK in monkeys was improved
compared to the first generation protease inhibitors.
2. McHutchinson, J. G.; Lawitz, E. J.; Shiffman, M. L.; Muir, A. J.; Galler, G. W.;
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Although the sulfone capped analogues 51 and 52 clearly lacked
acceptable PK in rats, based on previous observations that oral
Table 4
Primary
a-ketoamides with improved replicon activity and monkey PK
O
H
N
NH2
N
H
N
H
N
R
O
O
O
R1
O
7. For BILN-2061, see: (a) Lamarre, D.; Anderson, P. C.; Bailey, M.; Beaulieu, P.;
Bolger, G.; Bonneau, P.; Bös, M.; Cameron, D. R.; Cartier, M.; Cordingley, M. G.;
Faucher, A.-M.; Goudreau, N.; Kawai, S. H.; Kukolj, G.; Lagacé, L.; LaPlante, S. R.;
Narjes, H.; Poupart, M.-A.; Rancourt, J.; Sentjens, R. E.; George, T. S.; Simoneau,
B.; Steinmann, G.; Thibeault, D.; Tsantrizos, Y. S.; Weldon, S. M.; Yong, C.-L.;
Llinàs-Brunet, M. Nature 2003, 426, 186; (b) Tsantrizos, Y. S.; Bolger, G.;
Bonneau, P.; Cameron, D. R.; Gordreau, N.; Kukolj, G.; LaPlante, S. R.; Llinas-
Brunet, M.; Nar, H.; Lamarre, D. Angew. Chem., Int. Ed. 2003, 42, 1355.
8. For VX-950, see: (a) Yip, Y.; Victor, F.; Lamar, J.; Johnson, R.; Wang, Q.; May, G.;
John, I.; Yumibe, N.; Wakulchik, M.; Munroe, J.; Chen, S.-H. Bio. Med. Chem. Lett.
2004, 14, 5007; (b) Perni, R. Presented at the Gordon Research Conference, New
London, New Hampshire, August 2005.
9. For SCH 503034, see: (a) Njoroge, F. G.; Chen, K. X.; Shih, N.-Y.; Piwinski, J. J.
Account Chem. Res. 2008, 41, 50; (b) Venkatraman, S.; Bogen, S. L.; Arasappan,
A.; Bennett, F.; Chen, K.; Jao, E.; Liu, Y.-T.; Lovey, R.; Hendrata, S.; Huang, Y.;
Pan, W.; Parekh, T.; Pinto, P.; Popov, V.; Pike, R.; Ruan, S.; Santhanam, B.;
vibulbhan, B.; Wu, W.; Yang, W.; Yang, W.; Kong, J.; Liang, X.; Wong, J.; Liu, R.;
Butkiewicz, N.; Chase, R.; Hart, A.; Agarwal, S.; Ingravallo, P.; Pichardo, J.; Kong,
R.; Baroudy, B.; Malcolm, B.; Guo, Z.; Prongay, A.; Madision, B. L.; Cui, X.; Cheng,
K.-C.; Hsieh, T. Y.; Brisson, J.-M.; Prelusky, D.; Kormacher, W.; White, R.;
Bogonowich-Knipp, S.; Pavlovsky, A.; Prudence, B.; Saksena, A. K.; Ganguly, A.;
Piwinski, J.; Girijavallabhan, V.; Njoroge, F. G. J. Med. Chem. 2006, 49, 6074.
10. Zhang, R.; Beyer, B. M.; Durkin, J.; Ingram, R.; Njoroge, F. G.; Windsor, W. T.;
Malcolm, B. A. Anal. Biochem. 1999, 270, 268. The substrate Ac-DTEDVVP(Nva)-
O-PAP was used in the present study.
*
Compound
R
R1
Ki
EC90
Rat PO
Monkey
AUC
3 mpk
(nM) (nM) AUC,
10 mpk
M h)
(l
(lM h)
BoceprevirÓ
14
7
350
180
100
80
1.52
0.56
0.05
0.07
0.12
N
38
51
52
16.4
4.0
O
O
S
12
3
O
O
S
3.2
O
O
H
N
H
N
H
N
NH2
N
N
H
N
H
H
N
H
N
O
O
O
O
N
11. Taremi, S. S.; Beyer, B.; Maher, M.; Yao, N.; Prosise, W.; Weber, P. C.; Malcolm,
B. Protein Sci. 1998, 7, 2143.
O
O
O
O
*
12. For a definition of Ki and discussions, see: Morrison, J. F.; Walsh, C. T. In Adv.
Enzymol., Meister, A., Ed.; 1988, Vol. 61, pp 201–301.
13. (a) Chung, v.; Carroll, A. R.; Gray, N. M.; Parry, N. R.; Thommes, P. A.; Viner, K.
C.; D’Souza, E. A. Antimicrob. Agents Chemother. 2005, 49, 1381; (b) Blight, K. J.;
Kolykhalov, A. A.; Rice, C. M. Science 2000, 290, 1972; (c) Lohmann, V.; Körner,
F.; Koch, J.-O.; Herian, U.; Theilmann, L.; Bartenschlager, R. Science 1999, 285,
110.
54
53
Ki* = 100 nM
Ki* = 280 nM
Rat PK (10mpk,PO)
AUC=2.53uM.hr)
Rat PK (10mpk, PO)
AUC=26uM.hr
14. Crystallographic data for compound 2 bound to HCV NS3 protease have been
deposited with the RCSB Protein Data Bank and has been assigned the RCSB ID
code rcsb057547 and PDB ID code 3LOX.
Figure 6. Improvement of PK parameters in rats by introduction of a P10 ligand
(allyl amide; 53 vs 54).