208
D. H. Nam et al. / Bioorg. Med. Chem. Lett. 18 (2008) 205–209
123.2, 117.3, 115.9, 57.2, 43.5, 36.4, 11.3. Compound 3f:
mp 167–168 °C; H NMR (400 MHz, DMSO-d6) d 9.37–
most potently inhibited l-calpain activity (IC50 = 0.71–
0.73 lM), thus indicating that the 4-quinolinone ring
can be considered as a new scaffold for l-calpain inhib-
itors. Discussions concerning the structures of chro-
mone and 4-quinolinone series in relation to their
inhibitory activities contribute to our understanding of
the structural features required for inhibitors binding
to the active site of the enzyme and to the design of more
selective and potent l-calpain inhibitors for the treat-
ment of calpain-associated diseases.
1
9.33 (2H, m, –NH), 8.07 (1H, d, J = 8.0 Hz, quinolinone-
H5), 7.63–7.59 (2H, m, quinolinone-H7,8), 7.32–7.25 (6H,
m, aromatic), 7.21 (2H, d, J = 8.5 Hz, methoxybenzyl-
H2,6), 6.88 (2H, d, J = 8.5 Hz, methoxybenzyl-H3,5), 5.57
(1H, m, –NH–CH–CH2–Ph), 4.29 (2H, m, –NH–CH2–
Ar), 3.32 (3H, s, –OCH3), 3.21 (1H, dd, J = 3.9, 14.1 Hz,
–NH–CH–CH2–Ph), 2.87 (1H, dd, J = 9.7, 14.1 Hz, –NH–
CH–CH2–Ph), 1.85 (3H, s, –C@C–CH3); 13C NMR
(100 MHz, DMSO-d6) d 196.1, 177.5, 164.2, 160.5, 158.8,
142.3, 139.6, 127.6, 132.1, 130.8, 129.5, 128.9, 127.2, 125.3,
123.3, 118.7, 114.2, 56.3, 55.5, 42.1, 35.2, 11.6. Compound
3g: mp 181–182 °C; 1H NMR (400 MHz, DMSO-d6) d
9.37–9.31 (2H, m, –NH), 8.07 (1H, d, J = 8.0 Hz, quinoli-
none-H5), 7.63–7.58 (2H, m, quinolinone-H7,8), 7.61–6.79
(6H, m, aromatic), 6.94 (1H, s, dimethoxybenzyl-H2), 6.89
(1H, d, J = 8.2 Hz, dimethoxybenzyl-H5), 6.80 (1H, d,
J = 8.2 Hz, dimethoxybenzyl-H6), 5.57 (1H, m, –NH–
CH–CH2–Ph), 4.32–4.28 (2H, m,–NH–CH2–Ar), 3.72
(6H, s, –OCH3), 3.23 (1H, dd, J = 4.0, 14.1 Hz, –NH–
CH–CH2–Ph), 2.89 (1H, dd, J = 9.7, 14.1 Hz, –NH–CH–
CH2–Ph), 1.85 (3H, s, –C@C–CH3); 13C NMR (100 MHz,
DMSO-d6) d 196.1, 177.5, 164.2, 160.6, 149.0, 148.4, 142.3,
13936, 137.6, 132.1, 131.3, 129.4, 128.8, 127.2, 125.3,
123.7, 123.3, 120.1, 118.7, 114.2, 112.2, 112.1, 56.3, 56.0,
Acknowledgment
This research was supported by the Mid-Term Techno-
logical Development Project funded by the Korean Min-
istry of Commerce, Industry and Energy (Grant No.
10027898-2007-22).
References and notes
1. Sorimachi, H.; Ishiura, S.; Suzuki, K. Biochem. J. 1997,
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D. R.; Medhi, S.; Koehl, J. R.; Chmielwski, P. A.; Linnik,
M. Stroke 1998, 29, 152.
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5. Mehdi, S. Trends Biochem. Sci. 1991, 16, 150.
6. Shirasaki, Y.; Yamaguchi, M.; Miyashita, H. J. Ocul.
Pharmacol. Ther. 2007, 22, 417.
7. Fehrentz, J. A.; Castro, B. Synthesis 1983, 676.
8. Lee, K. S.; Seo, S. H.; Lee, Y. H.; Kim, H. D.; Son, M. H.;
Chung, B. Y.; Lee, J. Y.; Jin, C.; Lee, Y. S. Bioorg. Med.
Chem. Lett. 2005, 15, 2857.
9. Lubisch, W.; Beckenbach, E.; Bopp, S.; Hofmann, H.-P.;
Kartal, A.; Kaestel, C.; Lindner, T.; Metz-Garrecht, M.;
Reeb, J.; Regner, F.; Vierling, M.; Moeller, A. J. Med.
Chem. 2003, 46, 2404.
10. Steck, E. A.; Hallock, L. L.; Holland, A. J. J. Am. Chem.
Soc. 1946, 68, 129.
11. Harbenson, S. L.; Albelleira, S. M.; Akiyama, A.; Barret,
R., III; Carroll, R. M.; Straub, J. A.; Tkacz, J. N.; Wu, C.
C.; Musso, G. F. J. Med. Chem. 1994, 37, 2918.
12. Wells, G. J.; Tao, M.; Josef, K. A.; Bihovsky, R. J. Med.
Chem. 2001, 44, 3488.
13. Analytical data for selected final compounds. Compound
3a: mp 191–192 °C; 1H NMR (400 MHz, DMSO-d6) d
9.32 (1H, d, J = 7.0 Hz, –NH), 8.20 (1H, s, –NH), 8.07
(1H, d, J = 8.2 Hz, quinolinone-H5), 7.93 (1H, s, –NH),
7.61–7.60 (2H, m, quinolinone-H7,8), 7.33–7.24 (6H, m,
aromatic), 5.57 (1H, m, –NH–CH–CH2–Ph), 3.23 (1H, dd,
J = 3.9, 14.2 Hz, –NH–CH–CH2–Ph), 2.84 (1H, dd,
J = 10.0, 14.2 Hz, –NH–CH–CH2–Ph), 1.58 (3H, s,
–C@C–CH3); 13C NMR (100 MHz, DMSO-d6) d 196.5,
177.5, 164.2, 162.6, 142.3, 139.6, 137.7, 132.1, 129.4, 128.9,
127.1, 125.3, 123.7, 123.3, 118.7, 114.2, 65.0, 35.1, 11.6.
Compound 3e: mp 221–222 °C; 1H NMR (200 MHz,
CDCl3) d 9.42 (1H, br s, –NH) 8.37 (1H, br s, –NH), 8.17
(1H, d, J = 8.0 Hz, quinolinone-H5), 7.55–6.86 (13H, m,
aromatic), 5.85 (1H, m, –NH–CH–CH2–Ph), 4.63–4.42
(2H, m, –NH–CH2–Ph), 3.65 (1H, dd, J = 4.4, 14.2 Hz,
–NH–CH2–Ph), 3.26 (1H, dd, J = 9.2, 14.2 Hz, –NH–
CH2–Ph), 1.95 (3H, s, –C@C–CH3); 13C NMR (50 MHz,
CDCl3) d 194.9, 178.9, 164.1, 159.0, 139.1, 138.0, 136.6,
135.8, 132.0, 129.5, 128.9, 128.0, 127.9, 127.4, 125.6, 123.6,
1
55.8, 42.4, 35.2, 11.6. Compound 3j: mp 218–219 °C; H
NMR (400 MHz, DMSO-d6) d 9.33 (1H, d, J = 6.8 Hz,
–NH), 8.97 (1H, t, J = 5.4 Hz, –NH), 8.07 (1H, d,
J = 8.0 Hz, quinolinone-H5), 7.59 (2H, m, quinolinone-
H7,8), 7.31–7.17 (11H, m, aromatic), 5.56 (1H, m, –NH–
CH–CH2–Ph), 3.45–3.37 (2H, m, –NH–CH2–CH2–), 3.16
(1H, m, –NH–CH–CH2–Ph), 2.82–2.77 (3H, m, –NH–
CH2–CH2–, –NH–CH–CH2–Ph), 1.85 (3H, s, –C@C–
CH3); 13C NMR (100 MHz, DMSO-d6) d 196.1, 177.5,
164.2, 160.5, 142.3, 139.6, 139.5, 137.7, 132.1, 129.5, 129.1,
128.9, 128.8, 127.2, 126.6, 125.3, 123.7, 123.4, 118.7, 114.2,
56.4, 39.5, 35.1, 34.1, 11.6. Compound 3k: mp 172–173 °C;
1H NMR (400 MHz, DMSO-d6) d 9.30 (1H, d, J = 7.0 Hz,
–NH), 8.92 (1H, t, J = 5.9 Hz, –NH), 8.07 (1H, d,
J = 8.2 Hz, quinolinone-H5), 7.61–7.59 (2H, m, quinoli-
none-H7,8), 7.34–7.23 (6H, m, aromatic), 7.13 (2H, d,
J = 8.6 Hz, methoxyphenyl-H2,6), 6.84 (2H, d, J = 8.6 Hz,
methoxyphenyl-H3,5), 5.54 (1H, m, –NH–CH–CH2–Ph),
3.67 (3H, s, –OCH3), 3.40–3.32 (2H, m, –NH–CH2–CH2–
Ph), 3.16 (1H, dd, J = 3.8, 14.1 Hz, –NH–CH–CH2–Ph),
2.81–2.71 (3H, m, –NH–CH2–CH2–, –NH–CH–CH2–Ph),
1.85 (3H, s, –C@C–CH3); 13C NMR (100 MHz, DMSO-
d6) d 196.1, 177.5, 164.2, 160.5, 158.1, 142.3, 139.6, 137.7,
132.1, 131.2, 130.0, 129.5, 128.8, 127.2, 125.3, 123.7, 123.3,
118.7, 114.2, 56.3, 55.3, 40.0, 35.0, 34.1, 11.6.
14. Calpain inhibitory activity was assayed using a slight
modification of a reported procedure.15 Briefly, calpain I
(Calbiochem) from human erythrocytes and the fluoro-
genic calpain substrate (Suc-Leu-Tyr-7-amino-4-methyl-
coumarin, Calbiochem) were used as an enzyme and
substrate, respectively. In a typical experiment, 1 ll of a
compound solution at various concentrations, 25 ll of
1 mM calpain substrate, 10 ll of 1 M NaCl, and 11 ll of
1 mM CaCl2 were added to each well of 96-well plates. All
chemicals except for the compounds concerned were
dissolved in 50 mM Tris–HCl (pH 7.5) buffer containing
1 mM dithiothreitol and used immediately. The com-
pounds were dissolved in DMSO, but the DMSO
concentrations in the final experimental solutions did not
exceed 1%. Incubations were initiated by adding 53 ll of
34 nM calpain and the mixture was incubated for 30 min
at room temperature. After incubation, the fluorescence of
the cleavage product, 7-amino-4-methylcoumarin, was