16
A. Palumbo et al. / Bioorg. Med. Chem. Lett. 12 (2002) 13–16
small, yet significant non-competitive component in the
5
mL) is added, and the mixture is left for 24 h at rt. After
extraction with water (3ꢃ100 mL), the organic layer is dried
and the residue is triturated with boiling light petroleum to
give, after recrystallization, 3-nitrocatechol (4) as yellow nee-
dles (2.7 g, 19% yield). Column purification of the light pet-
roleum unsoluble fraction with chloroform/ethyl acetate 8:2
inhibitory action of 6-nitrocatecholamines which is not
observable in the case of 3. In fact, the proposed inter-
action of the amino side chain of 1 should increase
binding to the enzyme with respect to 3 which does not
seem to be supported by experimental data. Available
evidence does not allow to assess this point, which mer-
its further investigation. It can be speculated that in the
case of nitrocatecholamines the gain of energy derived
from interaction of the side chain with the negatively
charged residue is partially vained by a less efficient
binding to the heme iron center due to molecular
distortion (Fig. 4).
ꢁ
1
gave 4-nitrocatechol (3) in 40% yield. 4: mp 87 C; H NMR
acetone-d ) d (ppm) 6.84 (1H, dd, J=8 Hz, 8 Hz), 7.12 (1H,
dd, J=8 Hz, 1.6 Hz), 7.53 (1H, dd, J=8, 1.6 Hz); C NMR d
ppm) 116.96 (CH), 121.10 (CH), 123.42 (CH), 137.2 (C),
(
6
13
(
+
146.2 (C), 150.0 (C);EI-MS: m/z 155 (M ). Anal. calcd for
NO : C, 46.45;H, 3.22;N, 9.03. Found: C,46.40;H, 3.15;
N, 9.12.
. Catechol nitration with nitrite in acid media. General pro-
C
H
6 5
4
9
cedure. A solution of the appropriate catechol (1 mmol) in
water (6 mL) is added with sodium nitrite (4 mmol) and 96%
sulfuric acid (0.5 mL) in an ice-bath under stirring. After 30
min the reaction product is obtained either by filtration or by
column chromatography purification (silica gel, eluant
chloroform/ethyl acetate).
In summary, the results of this study provide evidence
that the aminoethyl side chain is the structural element
of 6-nitrocatecholamines specifically determining BH4-
antagonizing properties. This finding offers new leads
for the shaping of innovative, nitrocatechol-based
pharmacophores of potential therapeutic interest. Fur-
ther insights await the availability of a broader range of
nitrocatechols, whose preparation was beyond the
restricted scope of the present study and was deferred to
a more detailed investigation of quantitative structure–
activity relationships.
10. Norman, R. O. C.;Radda, G. K. J. Chem. Soc., Perkin
Trans. 1 1961, 3030.
11. Napolitano, A.;d’Ischia, M.;Costantini, C.;Prota, G.
Tetrahedron 1992, 48, 8515.
1
1
2. H NMR (acetone-d
6
) d (ppm) 2.29 (3H, s), 7.60 (1H, d,
1
3
J=2.4 Hz), 7.64 (1H, d, J=2.4 Hz); C NMR d (ppm) 108.6
(
(
CH), 118.5 (CH), 125.4 (CH), 140.3 (C), 145.1 (C), 151.33
+
C). EI-MS: m/z 169 (M ). Anal. calcd for C H NO : C,
7
7
4
5
1
1
8.00;H, 4.14;N, 8.28. Found: C, 58.08;H, 4.32;N, 8.20.
3. Novellino, L.;d’Ischia, M.;Prota, G. Synthesis 1999, 793.
4. Beake, B. D.;Constantine, J.;Moodie, R. B. J. Chem.
References and Notes
Soc., Perkin Trans. 2 1994, 335.
15. Daiber, A.;Mehl, M.;Ullrich, V. Nitric Oxide 1998, 2,
259.
1
2
. d’Ischia, M.;Costantini, C. Bioorg. Med. Chem. 1995, 3, 923.
. de la Breteche, M. L.;Servy, C.;Lenfant, M.;Ducrocq, C.
Tetrahedron Lett. 1994, 35, 7231.
. Daveu, C.;Servy, C.;Dendane, M.;Marin, P.;Ducrocq, C.
Nitric Oxide 1997, 1, 234.
. Palumbo, A.;Napolitano, A.;Barone, P.;d’Ischia, M.
Chem. Res. Toxicol. 1999, 12, 1213.
16. Manini, P.;d’Ischia, M.;Prota, G. J. Org. Chem. 2000, 65,
4269.
3
17. Lehning, M. Tetrahedron Lett. 1999, 40, 2299.
18. Chasteen, N. D.;Grady, J. K.;Skorey, K. I.;Neden, K. J.;
Riendeau, D.;Percival, M. D. Biochemistry 1993, 32, 9763.
19. Witteveen, C. F. B.;Giovanelli, J.;Kaufman, S. J. Biol.
Chem. 1999, 15, 29755.
4
5
3
6
. Palumbo, A.;Astarita, G.;d’Ischia, M. Biochem. J. 2001,
56, 105.
. Mayer, B.;Klatt, P.;Werner, E. R.;Schmidt, K.
Neuro-
20. Garcia-Moreno, M.;Rodriguez-Lopez, J. N.;Martinez-
Ortiz, F.;Tudela, J.;Varon, R.;Garcia-Canovas, F.
Biochem. Biophys. 1991, 228, 427.
pharmacology 1994, 33, 1253.
. HNO /H SO ;HNO /AcOH;HNO
NaNO /H SO –Et O/H O;HNO /CH Cl , for a review see
Arch.
7
3
2
4
3
3
/Ac
2
O;NaNO
2
/
21. Li, H.;Raman, C. S.;Glaser, C. B.;Blasko, E.;Young,
T. A.;Parkinson, J. F.;Whiltow, M.;Poulos, T. J. Biol. Chem.
1999, 274, 21276.
22. Molecular mechanics (MM+) calculation were carried
out with Hyperchem 5.0 package produced by Hypercube
Inc., 1997.
3
2
4
2
2
3
2
2
Olah, G. A.;Malhotra, R.;Narang, S. C. Nitration;VCH:
Weinheim 1989;Schonfield, K. Aromatic Nitration;Cam-
bridge University Press: Cambridge, 1980.
8
. Catechol nitration with HNO : To a solution of catechol
3
(
10 g) in ethyl ether (500 mL) in a ice bath fuming nitric acid (4