CONICET | Buscador de Institutos y Recursos Humanos

Determining the UV absorbance at 234 and 280 nm enables a quick determination of the oxidation progress in lipid membranes. Nevertheless, the experimental spectra result from a significant overlapping of bands arising from different oxidation products. The calculation of theoretical electronic spectra of the plausible oxidation products can provide a strong support for spectral interpretation. The goal of this work was to set-up a UV-based method to assess the peroxidation products of lecithin liposomes. UV spectra of liposomes exposed to H2O2 and CuSO4 were registered and peak-fitted to determine the overlapped bands contributing to the experimental features. Time-Dependent Density Functional Theory (TD-DFT) calculations were used to optimize the molecular structures and assess the theoretical UV spectra of all possible oxidation products. Two oxidation routes were considered: one of them conducting to the formation of conjugated dienes, and the other one, to the formation of hydroxy fatty acids. The integrated experimental and theoretical analysis of the UV spectra showed the presence of conjugated dienes M and N in the experimental spectra, occurring at λmax240 nm and fitting well the band at λmax237 obtained after deconvolution. In turn, compounds A, D, H and I, arising from the hydroxy fatty acids´ pathway, were those leading to the experimental bands at λmax225, 232 and 244 nm. The integrative computational and experimental approach carried out in this work provided a better understanding of lipid peroxidation processes.

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