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| Author(s): |
Danielle Cristine Almeida Silva de Santana
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Ciências Farmacêuticas de Ribeirão Preto (PCARP/BC) |
| Defense date: | 2010-06-14 |
| Examining board members: |
Maria Vitoria Lopes Badra Bentley;
Cristiane Masetto de Gaitani;
Maria Palmira Daflon Gremião;
Elia Tfouni
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| Advisor: | Renata Fonseca Vianna Lopez |
| Abstract | |
NO is an endogenous molecule that is involved in numerous physiological and pathological processes. Several compounds capable of releasing NO in vivo have been studied, including nitrosyl ruthenium complexes such as the [Ru (terpy)(bdqi-COOH)NO](PF6)3 that is capable of releasing NO after photo-stimulus. Because the specific role of NO depends on its location and kinetics of release, and its topical application may avoid possible side effects, the aim of this work was to study the passive and the iontophoretic skin absorption of the [Ru(terpy)(bdqi-COOH)NO](PF6)3 complex, as well as its NO release. The cytotoxic activity of the complex was also studied in A431 tumor cells in the presence and absence of light and electrical current. An analytical method for the quantification of the ruthenium complex by HPLC was developed and validated; studies of pre-formulation such as solubility, partition coefficient and stability of the complex were also performed before the penetration studies. The ruthenium complex was stable in aqueous solution at room temperature for 48 hours, but unstable in contact with the full-thickness skin (61% was degraded after 8 h). However, the complexs contact for 4 h with the stratum corneum (SC) alone did not lead to the complex degradation. The application of a weak electric current in a solution of the complex at physiological pH did not affect its stability, which showed no significant degradation for 6 h. In the passive penetration studies it was observed, by HPLC and inductively coupled plasma-mass spectrometry (ICP-MS), that the complex was able to penetrate the SC without degradation, but with some NO release when in contact with the epidermis. The application of iontophoresis significantly increased the amount of ruthenium in the viable epidermis and in the receiver solution (6 and 15 times, respectively), indicating greater complex penetration. The nitrosyl ruthenium complex and its aquo complex (formed after release of NO) showed no cytotoxicity to A431 cells in the absence of light. The irradiation of the cells incubated with the complex, passively, in 377 and 532 nm with different doses also did not cause significant cell death. However, the application of a constant electric current (0.3 mA cm-2) for 30 min followed by incubation for 4 h with the complex led to approximately 50% of A431 cell death after irradiation at 377 nm with a dose of 10J cm-2. To achieve this same result with irradiation at 532 nm it was necessary to increase the incubation time with the complex for 24 hours. In summary, the electric current increased the nitrosyl ruthenium complex skin and cell penetration, leading to release of higher amounts of NO into them, with consequent cell death. Furthermore, the release of NO from the ruthenium complex is showed to happen not only by light stimuli but also by redox reactions when it is in contact with the skin or with the culture of cells studied. Therefore, we propose the encapsulation of this complex in delivery systems in order to control the release of NO. Preliminary experiments with nanoparticles containing the complex are described in Appendix 1. (AU) | |
| FAPESP's process: | 06/02901-1 - Drug delivery systems containing a nitrosyl ruthenium complex releasing NO for topical photodynamic therapy |
| Grantee: | Danielle Cristine Almeida Silva de Santana |
| Support Opportunities: | Scholarships in Brazil - Doctorate |