29th Annual Meeting of the American Society of Photobiology

Downtown Marriot

Chicago, Il.

July 7th-12th, 2001

Ruthenium Nitrosyl Complexes as Nitric Oxide deliverers capable to be used in PDT

Tedesco, Antonio1, Togniolo, Vanessa2, Sauaia, Márilia2, Ceron, Patricia1 and da Silva, Roberto2
Faculdade de Filosofia Ciências e Letras de Rib. Preto- FFCLRP- Universidade de São Paulo1
Faculdade d Ciências Farmacêuticas de Rib. Preto -FCFRP- Universidade de São Paulo2

Abstract-
Nitric oxide (NO) has been implicated in many physiological and pathophysiological processes and has been shown to have many bioregulatory functions. Therefore, it is not surprising that the use of metalonitrosyl complexes as agents potentially capable of releasing NO in vivo has recently become a very active area of research . One strategy would be to employ a complex which is photochemically active to yield NO when subjected to electronic excitation . We have studied the photochemistry of cis-[Ru(py)(bpy)2(NO)](PF6)3 and trans-[RuCl([15]aneN4)NO](BF4)2, where py is pyridine, bpy is bipyridine and [15]aneN4 is a macrocycle ligand. The nitrosyl complexes were obtained by bubbling NO in cis-[Ru(py)(bpy)2(H2O)]2+ and trans-[RuCl([15]aneN4)(H2O)]+. The ultraviolet-visible spectra were recorded on a Hitachi U-3501. Infrared (i.r.) spectra were recorded on a protege 460 series FT-IR spectrometer. Cyclic voltammetry was performed with a Microquimica model MQPG 01. Quantum yields were determined using a laser flash-photolysis apparatus consisting of a Continuum Q-switched Nd-YAG laser(Continuum, Santa Clara, CA) with excitation provided by the third harmonic at = 355 nm. The NO release was measured with an ISO-NOP NO meter from Word Precision Instruments. The ultraviolet-visible spectra of the nitrosyl complexes show a metal-ligand charge transfer band in the 350 nm region; the FT-IR has a signal at 1930 cm-1 region characterized as NO stretching; the reduction potential of both complexes were found in a - 0.40 v and - 0.80 V vs AgCl/Ag region. The irradiation in physiological solution has showed NO release as described in the Scheme 1 for both nitrosyl complexes. The in situ NO monitoring during photolysis was used to prove the NO release.[RuII(L)(MAC)NO]n+ ---h--> [Ru III(L)(MAC)H2O]n+ + NO. We conclude that the photochemistry of cis-[Ru(py)(bpy)2(NO)]3+ and trans-[RuCl([15]aneN4)NO]2+ in physiological solution released NO when the compound was irradiated(Supported by Fapesp and CNPq).

Keywords: Ruthenium Nitrosyl Complexes, Photodynamic Therapy, Nitric Oxide