P. Barraja et al. / Bioorg. Med. Chem. Lett. 13 (2003) 2809–2811
2811
3. Dall’Acqua, F.; Viola G. In Photobiology for the 21th cen-
tury; Coohil T. P., Valenzeno D. P. Eds. Valdenmar: Overland
Park, KS, 2001; p 325.
4. Quanten, E.; Adriaens, P.; De Schryver, F. C.; Roelandts,
R.; Degreef, H. Photochem. Photobiol. 1986, 43, 485.
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Heterocyclic Chem. 1987, 24, 1041.
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chetti, F.; Carlassare, F.; Vedaldi, D.; Caffieri, S.; Pozzan, A.;
Dall’Acqua, F. J. Med. Chem. 1996, 39, 1293.
7. (a) Barraja, P.; Diana, P.; Lauria, A.; Passannanti, A.;
Almerico, A. M.; Minnei, C.; Longu, S.; Congiu, D.;
Musiu, C.; La Colla, P. Bioorg. Med. Chem. 1999, 7, 1591.
(b) Cirrincione, G.; Almerico, A. M.; Barraja, P.; Diana, P.;
Lauria, A.; Passannanti, A.; Pani, A.; Pinna, E.; Scintu, F.;
Musiu, C.; Pisano, L.; La Colla, P. J. Med. Chem. 1999, 42,
2561.
8. Stetter, H.; Lauterbach, R. Liebigs. Ann. Chem. 1962, 652,
40.
Figure 1. Absorbance (A), and linear dichroism (LD) spectra of mix-
tures of salmon testes DNA and compounds 11 (A1, B1) and 12 (A2,
B2) at different [Drug]/[DNA] ratio (a=0.00, b=0.02, c=0.04).
9. All final products were characterized by IR, 1H and 13C
NMRand elemental analysis. A representative example, com-
ꢀ
À1
pound 11: 80% mp>300 C; IR2921 (NH), 1635 (CO) cm
;
1H NMR(DMSO- d6): 2.02 (3H, s, CH3), 2.56 (2H, t, J=7.6
Hz, CH2), 2.80 (2H, t, J=7.6 Hz, CH2), 6.71 (1H, s, H-9), 7.38
(2H, d, J=6.8, Ar), 7.50–7.69 (6H, m, Ar), 7.96 (2H, d, J=6.8
Hz, Ar), 8.10 (1H, s, H-4), 12.24 (1H, s, NH); 13C NMR
(DMSO-d6): 12.5 (q), 20.8 (t), 25.4 (t), 103.3 (d), 107.0 (s),
111.8 (s), 118.1 (s), 127.2 (2Âd), 127.5 (2Âd), 128.4 (3Âd),
129.4 (2Âd), 130.8 (s), 132.5 (d), 136.2 (s), 137.7 (s), 141.5(s),
142.0 (d), 148.6 (s), 158.2 (s). Anal. calcd for C24H20N2SO3: C,
69.21; H, 4.84; N, 6.73. Found: C, 69.11; H, 4.69; N, 6.53.
10. Antitumor assay. Exponentially growing HT-1080 human
fibrosarcoma cells were resuspended at a density of 5Â104
cells/mL in a complete medium (DMEM containing 10% fetal
bovine serum, 100 UI/mL penicillin G and 100 mg/mL strep-
tomycin) and seeded in a 96 well culture plates which were
allowed to adhere for 18 h to culture plates before addition of
the drugs. After the medium was removed, 100 mL of the drug
solution, dissolved in DMSO and diluted with Hank’s
balanced salt solution (HBSS pH=7.2), was added to each
well. The plate was then incubated for 30 min in an atmos-
phere of 5% CO2 at 37 ꢀC, the control plate was placed in the
dark and then irradiated with two HPW 125 Philips lamp,
principally emitting at 365 nm. After irradiation, the solution
was replaced by the medium and the plates were incubated for
72 h. Cell viability was assayed by the MTT [(3-(4,5-dime-
thylthiazol-2-yl)-2,5diphenyl tetrazolium bromide)] method.13
Cell growth at each drug concentration was expressed as per-
centage of untreated controls and the concentration resulting
in 50% (IC50) growth inhibition was determined by linear
regression analysis.
carried out with the same derivatives (data not shown)
showed a poor fluorescence quenching confirming that
the title compounds are loosely bound to DNA. This
fact strongly suggests that the new derivatives do not
interact efficaciously with the macromolecule. Con-
sidering these results, the new pyrroloquinolinones,
appear as novel and potentially useful agents in photo-
chemotherapy in so far as they show a remarkable photo-
antiproliferative activity which does not appear related to
the classical mechanism (i.e., formation of mono- and
bifunctional adducts to DNA) exerted by psoralens.
On the basis of the biological evaluation, experiments
aimed at defining the targets at cellular level and the
mechanism of phototoxycity are in progress.
Acknowledgements
This work was financially supported by Ministero
dell’Istruzione dell’Universita e della Ricerca.
References and Notes
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2. Musajo, L.; Rodighiero, G. In Photophysiology; Giese, A.
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11. Norde
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12. Norden, B.; Kurucsev, T. J. Mol. Recognit. 1994, 7, 141.
13. Mosmann, T. J. Immunol. Meth. 1983, 65, 55.
´
n, B.; Kubista, M.; Kurucsev, T. Q. Rev. Biophys.
´