C. Audouin et al. / Bioorg. Med. Chem. Lett. 11 (2001) 845–848
847
trans olefin and the corresponding alkane. In order to
circumvent this difficulty, separation was performed by
HPLC13 after transforming the carboxylic function into
MEM ester.14 This strategy led to pure cis olefin 13. The
MEM ester was cleaved by TFA and the resulting car-
boxylic acid 14 was coupled with 1-aminoindoline in the
presence of EDCI and HOBT.15 The carboxylate ester
was hydrolysed by NaOH to give compound 6 which
was coupled with N-decylamine under peptidic synthesis
conditions to give amide 7.
compound, and the presence of a sulfonyl group (3)
instead of its bioisosteric carbonyl group (2) seems to
increase the inhibition of 5-LO. Compound 4 is more
potent than the non-hydroxylated analogue 1: C5 sub-
stitution by a hydroxyl enhances 5-LO inhibition and
this group seems to be essential as regards enzyme
binding since compound 5, substituted at C5 by a
methoxy group, is less active. The introduction of the cis
hexenoic chain (6) has no influence. On the other hand,
amide 7, tested at 1 mM concentration because of low
solubility, could be attractive for further investigations.
The activities of these different compounds were eval-
uated in vitro and compared with those of phenidone
and NDGA (nordihydroguiaretic acid),16 the latter
being another antioxidant that inhibits 5-LO. Lipoxy-
genase products synthesised in RBL-1 cells—a rat
basophilic leukemia cell line—were analysed by HPLC.
The cells were harvested by centrifugation, washed with
phosphate buffer saline (PBS), pH 7.4, and resuspended
in PBS. Cells were stimulated and the reaction was
stopped as previously described.17 The 5-LO product
5-HETE was quantified by HPLC separation on a
Chromspher C18 column. Detection of 5-HETE was
carried out by UV absorbance at 130 nm. Compound 4
presented interesting activity (Table 1) and was sub-
mitted to IC50 determination (Scheme 5). Compound 4
is as active as phenidone, but less potent than NDGA in
vitro.
In conclusion, the prepared N-aminoindoline deriva-
tives are only moderately potent in inhibiting 5-LO.
However, further studies in the aminoindoline and ben-
zothiophene series (relative to Zileuton for example18)
are underway taking into account the preliminary and
encouraging results obtained on compounds 4 and 7,
and considering the fact that a sulfonyl group could
induce an increase in activity.
References and Notes
1. (a) Drazen, J. M.; Austen, K. F. Am. Rev. Respir. Dis.
1987, 136, 985. (b) Barnes, P. J. J. Allergy Clin. Immunol.
1989, 83, 1023. (c) Arm, J. P. In New Concepts in Asthma;
Tarayre, J. P., Vargaftig, B., Carilla, E., Eds.; MacMillan
Editions: London, 1993; pp 114–136. (d) Chanarin, N.; John-
ston, S. L. Drugs 1994, 47, 12.
2. (a) Rouzer, C. A.; Matsumoto, T.; Samuelsson, B. Proc.
Natl. Acad. Sci. U.S.A. 1986, 83, 857. (b) Samuelsson, B.;
Dahlen, S.-E.; Lindgen, J. A.; Rouzer, C. A.; Serhan, C. N.
Science 1987, 237, 1171. (c) Corey, E. J. Pure Appl. Chem.
1987, 59, 269. (d) Nelson, M. J.; Seitz, S. P.; Cowling, R. A.
Biochemistry 1990, 29, 6897. (e) Batt, D. G. In Progress in
Medicinal Chemistry; Ellis, G. P., Luscombe, D. K., Eds.;
Elselvier Science: Amsterdam, 1992; Vol. 29, pp 1–63. (f)
Brooks, D. W.; Summers, J. B.; Stewart, A. O.; Bell, R. L.;
Bouska, J.; Lanni, C.; Young, P. R.; Rubin, P.; Carter, G. W.
In Perspectives in Medicinal Chemistry; Testa, B., Kyburz, E.,
Fuhrer, W., Giger, R., Eds.; Verlag Helvetica Chimica Acta
Editions: Basel, 1993; pp 119–134.
The results offer several conclusions concerning phar-
macomodulations. Replacement of indoline (1) by a
non-cyclic skeleton (2) does not provide a more active
Table 1.
Compound
Inhibition% 10 mM
IC50 (mM)
NDGA
Phenidone
73Æ8a
0.41Æ0.20
—
2.54Æ0.53
1
2
3
4
5
6
7
15Æ15
n=3
n=3
n=4
n=4
n=4
n=3
n=2
—
—
—
28Æ3
53Æ19
80Æ8
3.47Æ0.93
3. (a) Musser, J. H.; Kreft, A. F. J. Med. Chem. 1992, 35,
2501. (b) Ford-Hutchinson, A. W.; Gresser, M.; Young, R. N.
Annu. Rev. Biochem. 1994, 63, 383. (c) Young, R. N. Eur. J.
Med. Chem. 1999, 34, 671.
4. Tamura, A.; Sato, T.; Fujii, T. Chem. Pharm. Bull. 1990,
38, 255.
20Æ18
18Æ9
—
—
—
57Æ8.5b
aTested at 0.5 mM.
bTested at 1 mM.
5. Viehe, H. G.; Merenyi, R.; Stella, R.; Janousek, Z. Angew.
Chem., Int. Ed. Engl 1979, 18, 917.
6. (a) Blackwell, G. J.; Flower, R. J. Prostaglandins 1978, 16,
417. (b) Hlasta, D. J.; Casey, F. B.; Ferguson, E. W.; Gangell,
S. J.; Heimann, M. R.; Jaeger, E. P.; Kullnig, R. K.; Gordon,
R. J. J. Med. Chem. 1991, 34, 1560.
7. Compound 7 possesses, like some compounds developed by
Pfizer, an N-decylamide function (Kadin, S. B. Eur. Pat. Appl.
EP 50,977 (Cl. C07C103/30); Chem. Abstr. 1982, 97, 144598b).
8. Wright, J. B.; Willette, R. E. J. Med. Pharm. Chem. 1962, 5,
815.
9. Glamkowski, E. J.; Reitano, P. A. J. Med. Chem. 1979, 22,
106.
10. Gribble, G. W.; Lord, P. D.; Skotnicki, J.; Dietz, S. E.;
Eaton, J. T.; Johnson, J. L. J. Am. Chem. Soc. 1974, 96, 7812.
11. (a) Robins, M. J.; Barr, P. J. J. Org. Chem. 1983, 48, 1854.
(b) Loffler, A.; Himberg, G. Synthesis 1990, 125. (c) Ciufolini,
M. A.; Weiss, T. J. Tetrahedron Lett. 1994, 35, 1127.
Scheme 5. Inhibition of 5-lipoxygenase activity by 4. Points represent
meansÆSEM of at least three determinations.