Full text
| |
| Author(s): |
Sayuri Miyamoto
Total Authors: 1
|
| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2005-04-08 |
| Examining board members: |
Paolo DI Mascio;
Maurício da Silva Baptista;
Etelvino José Henriques Bechara;
Carlos Bloch Júnior;
Rui Curi
|
| Advisor: | Paolo Di Mascio; Junji Terao |
| Abstract | |
Evidences point to the involvement of lipid peroxidation in several diseases. Lipid hydroperoxides (LOOH) are the primary products of lipid peroxidation and their decomposition generates more reactive and toxic compounds, such as peroxyl radicals. These radicals play an important role in the propagation of lipid peroxidation and may also generate singlet molecular oxygen (1O2) by the combination of two peroxyl radicals. In this study we have investigated the possibility of LOOH, in particular linoleic acid hydroperoxide (LAOOH), to be a source of 1O2 in the presence of biologically relevant oxidants such as, metal ions, peroxynitrite or hypochlorous acid. The formation of 1O2 was clearly demonstrated in the reaction of LAOOH with all the three tested oxidants by detecting: (i) the dimol light emission in the red spectral region (λ>570 nm), (ii) the monomol light emission in the near-infrared region (λ=1270 nm), (iii) the infrared light emission spectrum, and (iv) the enhancing effect of deuterium oxide and the quenching effect of azide on light emission. Furthermore, the mechanism was studied using LAOOH labeled with 18-oxygen isotope (LA18O18OH) and specific 1O2 chemical traps in combination with HPLC coupled to mass spectrometry detection. The results have showed the formation of 18-oxygen labeled 1O2 [18(1O2) ] in the reaction of LA18O18OH with the three oxidants, indicating that oxygen atoms in 1O2 are derived from the hydroperoxide. Altogether, the obtained evidences lead to the conclusion that LOOH may serve as a potential source of 1O2 in biological systems, in situations where LOOH can interact with metals, peroxynitrite or hypochlorous acid. (AU) | |