´
S. Levesque et al. / Bioorg. Med. Chem. Lett. 11 (2001) 3161–3164
3164
Table 2. In vivo parameters
Boudreau for conducting in vivo experiments, and Ms.
Lyne Marcil for her help in the preparation of this
manuscript.
Compd
Rat arterial thrombosis modela
APTTc
MOTb
TTd
8
25
23
48ꢃ13
>60
46ꢃ10
38ꢃ5
231ꢃ29
455ꢃ64
393ꢃ102
References and Notes
58ꢃ11
54ꢃ14
1. St-Denis, Y.; Augelli-Szafran, C. E.; Bachand, B.; Berry-
man, K. A.; DiMaio, J.; Doherty, A. M.; Edmunds, J. J.;
Leblond, L.; Levesque, S.; Narasimhan, L. S.; Penvose-Yi,
J. R.; Rubin, J.; Tarazi, M.; Winocour, P. D.; Siddiqui, M. A.
Bioorg. Med. Chem. Lett. 1998, 8, 3193.
aDose: intravenous bolus dose (0.75 mg/kg) followed byan infusion
(50 mg/kg/min).
bMean occlusion time in min (control: 17/19 min).
cActivated partial thromboplastin time in seconds (control: 20/22 s).
dThrombin time in seconds (control: 40/45 s).
2. Bachand, B.; Tarazi, M.; St-Denis, Y.; Edmunds, J. J.;
Winocour, P. D.; Leblond, L.; Siddiqui, M. A. Bioorg. Med.
Chem. Lett. 2001, 11, 287.
3. For other examples of non-covalent thrombin inhibitors
see: Fevig, J. M.; Wexler, R. R. Annu. Rep. Med. Chem. 1999,
34, 81.
4. Lyle, T. A.; Chen, Z.; Appleby, S. D.; Freidinger, R. M.;
Gardell, S. J.; Lewis, S. D.; Li, Y.; Lyle, E. A.; Lynch, J. J.;
Mulichak, A. M.; Ng, A. S.; Naylor-Olsen, A. M.; Sanders,
W. M. Bioorg. Med. Chem. Lett. 1997, 7, 67.
5. Kim, K. S.; Moquin, R. V.; Qian, L.; Morrison, R. A.;
Seiler, S. M.; Roberts, D. G. M.; Ogletree, M. L.; Youssef, S.;
Chong, S. Med. Chem. Res. 1996, 6, 377. See also: Kim, K. S.;
Kimball, S. D.; Das, J.; Iwanowicz, E. J.; Han, W.-C.
EP95108266.8, 1995.
The cyclohexylamine and piperidylamidine moieties
were comparable P1 residues in terms of thrombin affi-
nities. However, the cyclohexylamine residue displayed
an improved selectivityindex ( 28 vs 7b). The introduc-
tion of phenyl amidines improved the binding affinities
of inhibitors 25 and 23. However, there was a significant
loss of selectivity, presumably due to the reduced lipo-
philicityof the aromatic ring compared to the piperidyl
and cyclohexyl rings. Inhibitors 13, 18, and 26 were all
inactive, suggesting the highlyspecific nature of the P1
subsite.
The three inhibitors having the optimal in vitro poten-
cies were then tested in the rat arterial thrombosis
model (see Table 2, analogues 8, 25, and 23). All of
them displayed greater than 2-fold increase in mean
occlusion time. No occlusion was observed with inhi-
bitor 25 for the whole duration of the experiment
(60 min).
6. Nagahara, T.; Yokoyama, Y.; Inamura, K.; Katakura, S.-
I.; Komoriya, S.; Yamaguchi, H.; Hara, T.; Iwamoto, M. J.
Med. Chem. 1994, 37, 1200.
7. Finkle, C. D.; St-Pierre, A.; Leblond, L.; Deschenes, I.;
DiMaio, J.; Winocour, P. D. Thromb. Haemostasis. 1998, 79,
431.
8. Compound 27 was prepared in a straightforward manner
.
as shown below:
We have demonstrated that the activated carbonyl of
compounds 1 and 2 was not necessaryfor high potency
and selectivity. By modifying P1 residues of these inhi-
bitors, we could capture additional interactions in order
to improve the binding affinityand selectivityfor
thrombin. Selected compounds were administered via
intravenous infusion in the rat arterial thrombosis
model and were shown to have high in vivo efficacy.
Acknowledgements
The authors would like to acknowledge Ms. Brigitte
Grouix and Ms. Quan Yang for providing binding
constants, Ms. Isabelle Deschenes and Ms. Chantal
9. The authors have deposited X-raycrsytallographic data
with the Brookhaven Protein Data Bank. Deposition code
1JWT.