Chemical and photochemical aspects of control nitric oxide release from nitrosyl ruthenium complexes: pharmacological and cytotoxic assays.

Author(s)

Mario Sergio Pereira Marchesi

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Ciências Farmacêuticas de Ribeirão Preto (PCARP/BC)
• Defense date: 2008-08-18

Examining board members

Roberto Santana da Silva; Lusiane Maria Bendhack; Victor Marcelo Deflon; Regina Célia Galvao Frem; Sofia Nikolaou

• Advisor: Roberto Santana da Silva

Abstract

Nitric oxide (NO) is a multipurpose biological agent that shows important role in brain, arteries, immunological system, liver and lungs. The NO basal level alterations have correlation with several diseases as hypertension, cancer, Raymonds disease and platelet aggregation. Aiming supply this deficient NO level, it was necessary propose new compounds that can release NO at controlled manner. One of the possibilities is utilize nitrosyl ruthenium complexes that have ability to release NO under external stimulus. In this work we have studied, the chemical, photochemical, pharmacological and anti-tumoral properties of the trans-[RuC(MAC)NO]2+ complex, were MAC is 1,4,8,11-tetraazacyclotetradecane (cyclam) or 1,4,8,12-tetraazacyclopentadecane ([15]aneN4), in the presence of the sensitizer [Ru(NH3)5pz]2+. The photochemical studies of [Ru(NH3)5pz]2+ complex showed excited state lifetime of 113 ps and presented photoinduced electron and energy transfer with oxygen resulting in reactive oxygen species (ROS) generation as singlet oxygen and superoxide anion. In the presence of trans-[RuC(MAC)NO]2+ complex, the visible light irradiation of [Ru(NH3)5pz]2+ causes photoinduced electron transfer between the photosensitizer and the nitrosyl ruthenium complex resulting NO generation. The quantum yield (NO) is milieu dependent and showed 10-4 Einstein.mol.cm-1 in inert atmosphere and 10-2 Einstein.mol.cm-1 in aerated aqueous solution. The pharmacological studies showed that the proposed mixture in phosphate buffer, under visible irradiation, induce 75% of relaxation in aorta pre-contracted with KC while this system incorporated into drug delivery system as water-in-oil emulsion, HEG gel and sol-gel membrane, the nitric oxide generated induced 40%, 35% and 35% of relaxation, respectively. The quantification of cytosolic calcium concentration, using confocal image, showed that vasodilatation pathway observed was via cGMP (cyclic guanosine monophosphate) activation. The anti-tumoral studies using NO donors were carried out for B16F10, Melan A, HL-60, WMs and Jurkat cells. Those experiments showed decrease from 50% to 75% of cell viability of tumor cells and no toxicity in melanoma cells and 95% of reduction of leukemic cells (HL-60). The obtained results described in this work permit to glimpse that the use of NO donor species and singlet oxygen maybe is a useful tool in the future in clinical therapy. (AU)