Q. Wang et al. / Bioorg. Med. Chem. Lett. 10 (2000) 941±944
943
mM Ki values.51 The current study shows that simple C-
glycosides 1 and 2 display mM Ki values. Furthermore,
the more hydrophobic the aglycones aord greater
neuraminidase inhibitory activity. This is similar to
reports of the potent inhibitory activity of the octadecyl
glycoside of Neu5Ac.52 In a previous study in which C-
glycosides were prepared by replacement of the C-2
hydroxyl group with a hydroxylmethylene group, only
very weak inhibitory eects towards Vibrio cholerae
sialidase were observed.53 This might be due to the high
hydrophilicity of aglycone substitution, consistent with
the current study. Studies on S-linked Neu5Ac (2!6)
Glc and Gal demonstrated the importance of the C-4
con®guration of the hexose residue, as well as the
conformation about the S-glycosidic linkage on the
measured Ki.51,52 The current study shows that con®g-
uration at C-3 of the 2,3 linked Neu5Ac C-dis-
accharides 4 and 5 profoundly in¯uences the observed
Ki while the perturbation of the conformation about the
C-glycosidic linkage 3 and 4 appears to have little eect
on the Ki. Studies using liposomes,54 polymerized lipo-
somes,20 polymers55 and dendrimers56 of Neu5Ac deri-
vatives showed that multivalency can markedly enhance
ligand interaction and biological eects. Future studies
will examine whether improvements in C-glycoside
neuraminidase inhibitory activity can be obtained by
multivalency.
9. Sauter, N. K.; Glick, G. D.; Crowther, R. L.; Park, S. J.;
Eisen, M. B.; Skehel, J. J.; Knowles, J. R.; Wiley, D. C. Proc.
Natl. Acad. Sci. USA 1992, 89, 324.
10. Toogood, P. L.; Galliker, P. K.; Glick, G. D.; Knowles, J.
R. J. Med. Chem. 1991, 34, 3138.
11. Harms, G.; Reuter, G.; Cor®eld, A. P.; Schauer, R. Gly-
coconjugate J. 1996, 13, 621.
12. Swartley, J. S.; Mar®n, A. A.; Edupugantis, D.; Liu, L. J.;
Ceislak, P.; Perkins, B.; Wenger, J. D.; Stephans, D. S. Proc.
Natl. Acad. Sci. USA 1997, 94, 271.
13. Kaijser, B.; Jodal, U. J. Clin. Microbiol. 1984, 19, 264.
14. Toyokuni, T.; Singhal, A. K. Chem. Soc. Rev. 1995, 231.
15. Maclean, G. D.; Longenecker, B. M. Can. J. Oncol. 1994,
4, 249.
16. Livingston, P. O. Cancer Biol. 1995, 6, 357.
17. Colman, P. In The In¯uenza Viruses; Krug R., Ed.; Ple-
num: New York, 1989; pp 175±218.
18. Bamford, M. J. J. Enz. Inhib. 1996, 10, 1.
19. Kim, C. U.; Lew, W.; Williams, M. A.; Wu, H.; Zhang, L.;
Chen, X.; Escarpe, P. A.; Mendel, D. B.; Laver, W. G.; Ste-
vens, R. C. J. Med. Chem. 1998, 41, 2451.
20. Spevak, W.; Nagy, J. O.; Charych, D. H.; Schaefer, M. E.;
Gilbert, J. H.; Bednarski, M. D. J. Am. Chem. Soc. 1993, 115,
1146.
21. Arya, P.; Kutterer, K. M. K.; Qin, H.; Roby, J.; Barnes,
M. L.; Kim, J. M.; Roy, R. Bioorg. Med. Chem. Lett. 1998, 8,
1127.
22. Kuribayashi, T.; Ohkawa, N.; Satoh, S. Bioorg. Med.
Chem. Lett. 1998, 8, 3307.
23. Molander, G.; Harris, C. Chem. Rev. 1996, 96, 307.
24. Mazeas, D.; Skrydstrup, T.; Beau, J.-M. Angew. Chem.,
Int. Ed. Engl. 1995, 34, 909.
25. Hung, S.-C.; Wong, C.-H. Angew. Chem., Int. Ed. Engl.
1996, 35, 2671.
26. Depouilly, P.; Chenede, A.; Mallet, J.-M.; Sinay, P. Bull.
Soc. Chim. Fr. 1993, 130, 256.
27. Vlahov, I. R.; Vlahova, P. I.; Linhardt, R. J. J. Am. Chem.
Soc. 1997, 119, 1480.
In summary, the present study shows that certain Neu5Ac
C-glycosides are potent neuraminidase inhibitors dis-
playing Ki values comparable to those of the transition
state analogue Neu5Ac-2-ene (5-acetamido-2, 6-anhy-
dro-3, 5-dideoxy-d-glycero-d-galacto-non-2-enonic acid),
which is currently in clinical trials as an anti-in¯uenza
agent.40,41,57 A neuraminidase based on Neu5Ac C-gly-
cosides mimetic of the natural O-glycoside substrate
may take advantage of both tightly binding and resis-
tance enzyme cleavage. This property may lead to
longer retention time in vivo and higher inhibitory
eects aording a new class of antibacterial and anti-
viral agents.
28. Du, Y.; Linhardt, R. J. Carbohydr. Res. 1998, 308, 161.
29. Polat, T.; Du, Y.; Linhardt, R. J. Synlett 1998, 1195.
30. Bazin, H. G.; Du, Y.; Polat, T.; Linhardt, R. J. J. Org.
Chem. 1999, 64, 7254.
31. Lopez, R. M.; Hays, D. S.; Fu, G. C. J. Am. Chem. Soc.
1997, 119, 6949.
32. Myers, A. G.; Movassaghi, M.; Zheng, B. J. Am. Chem.
Soc. 1997, 119, 8572.
33. Entries 1 and 2 were synthesized28,29 containing the per-
acetylated methyl ester of Neu5Ac and compds. 3±527,30 also
contained a benzyl protected galactose or gulose residue.
Debenzylation of Entries 3±5 was accomplished by adding 50
mg to 10 mL of MeOH:EtOAc:H2O (4:4:2) containing 1 drop
of 80% HOAc (aq) and 15 mg of 5% Pd/C sealed with an H2
containing balloon with stirring for 24 h at rt. The mixture
was ®ltered and the ®ltrate recovered and peracetylated with
Ac2O in Py. These peracetylated C-disaccharides (or Entries 1
and 2) were deacetylated by dissolving in MeOH (36 mg/9 mL)
to which catalytic amount of NaOMe was added and stirred
for 19 h at rt, 1 mL of 0.2 M KOH (aq) was added and stirred
8 h at rt, neutralized with Amberlite IR-120 (H+), ®ltered,
and desalted on a Bio-gel P2 column. 1H NMR (500 MHz)
analyses of 1±5 were consistent with structure.
Acknowledgment
We thank Dr. Laurie LeBrun for helpful discussions on
the determination of enzyme kinetics.
References and Notes
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3. Varki, A. Proc. Natl. Acad. Sci. USA 1994, 91, 7390.
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34. Potier, M.; Mameli, L.; Belisle, M.; Dallaire, L.; Mel-
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35. Incubation mixtures contained 50 mL of 0.1 M sodium
acetate buer, pH 5.0 and 0.04 to 1.0 mM MU-Neu5Ac to
determine Km and same substrate concentration with 0.01 mM
to 0.1 mM inhibitor to determine Ki. Relative ¯uorescence was
recorded for 30 min beginning immediately after 0.5 mU
neuraminidase was added (in the blank the enzyme was omitted).
6. Lal, A.; Pang, P.; Kalelkar, S.; Romero, P. A.; Herscovics,
A.; Moremen, K. W. Glycobiology 1998, 8, 981.
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