Characterization of violacein photochemical properties

• Grant number: 05/03246-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2005
• End date: October 31, 2006
• Field of knowledge: Biological Sciences - Biophysics
• Principal Investigator: Iseli Lourenço Nantes Cardoso
• Grantee: Juliana Mafra Machado Nunweiler
• Host Institution: Pró-Reitoria de Pesquisa, Pós-Graduação e Extensão e Assuntos Comunitários. Universidade de Mogi das Cruzes (UMC). Mogi das Cruzes , SP, Brazil

Abstract

Literatura data have shown the cytotoxic potential of the fundamental state of violaceine in the free form or complexed with alpha-cyclodextrin, that in the both cases is due to the ability of the dye to induce apoptosis. Besides the anti-tumoral properties, violaceine presents other important effects such as antibiotic, anti-chagas, anti-parasite and anti-ulcerous activities. Violaceine exhibits also discrete anti-virus activity. On the other hand, the literature data about the properties of the excited state of violaceine are scarce and there is no data about the cytotoxic potential of the excited state of this dye. In the present project, it is proposed to characterize the photochemical and photophysical properties of violaceine in order to evaluate the potential this dye to be used in Photodynamic Therapy. Thus, it will be investigated the photophysical and photochemical properties of violaceine as a function of the aggregation state of the dye, the polarity of the medium, pH, ionic strength and the presence of charged interfaces such as micelles and liposomes. The photochemical and photophysical behavior of violaceine in different media will be characterized by UV-visible and fluorescence spectroscopy of the dye after the irradiation with a 500 Watts halogen lamp, the absorbance spectrum of the dye triplet state obtained by flash photolysis technique, detection of the generation of singlet oxygen by energy transfer from the dye triplet state and mass spectrometry of the dye photoproducts formed after the irradiation of the dye in different media.