CONICET | Buscador de Institutos y Recursos Humanos

Determining the UV absorbances at 234 nm and280 nm enables a quick determination of the oxidation progress in lipidmembranes. Nevertheless, experimental spectral results indicate a significantoverlapping of bands arising from different oxidation products. The calculationof theoretical electronic spectra of the plausible oxidation products can providestrong support for spectral interpretation. The goal of this work was to set upa UV-based method to assess the peroxidation products of lecithin liposomes. UVspectra of liposomes exposed to H2O2 and CuSO4 were recorded and peak-fitted todetermine the overlapping bands contributing to the experimental features.Time-dependent density functional theory (TD-DFT) calculations were used tooptimize the molecular structures and assess the theoretical UV spectra of allpossible oxidation products. Two oxidation routes were considered; one of themregarding the formation of conjugated dienes and the other related to theformation of hydroxy fatty acids. The integrated experimental and theoreticalanalysis of the UV spectra showed the presence of conjugated dienes M and N inthe experimental spectra, occurring at λmax ≈ 240 nm and fitting well in the band at λmax ≈ 237 obtained after deconvolution. In turn, compounds A, D, H and I,arising from the hydroxy fatty acid pathway, were those leading to theexperimental bands at λmax ≈ 225, 232 and244 nm, respectively. The integrative computational and experimental approachconducted in this work provides a better understanding of lipid peroxidationprocesses.

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