Methylene Blue Location in (Hydroperoxized) Cardiolipin Monolayer: Implication in Membrane Photodegradation

Autor(es)

de Souza, R. M. ; Siani, P. ; Schmidt, T. F. ; Itri, R. ; Dias, L. G.

• Tipo de documento: Artigo Científico
• Fonte: Journal of Physical Chemistry B; v. 121, n. 36, p. 8512-8522, SEP 14 2017.
• Citações Web of Science: 2

Resumo

We present molecular dynamics simulations of cardiolipin (CL) and CL monohydroperoxized derivative (CLOOH) monolayers to investigate the initial steps of phospholipid oxidation induced by methylene blue (MB) photoexcitation under continuous illumination. We considered different MB atomic charge distributions to simulate the MB electronic distribution in the singlet ground and triplet excited states. Simulation results allied to experimental data revealed that initial CL photooxidation probably occurs via a type II mechanism, to produce lipid hydroperoxide by singlet oxygen attack to the alkyl chain unsaturations. The resulting hydroperoxide group prefers to reside near the aqueous interface, to increase the membrane surface area and to decrease lipid packing. Interestingly, MB orientation changes from nearly parallel to the water-monolayer interface in the ground state to normal to the interface in its triplet excited state. The latter orientation favors oxidative chain reaction continuity via a type I mechanism, during which the hydrogen atom must be transferred from the hydroperoxide group to triplet MB. Taken together, the present results can be extrapolated to improve our understanding of how oxidation progresses in lipidic biomembrane, which will lead to the formation of oxidized species with shortened chains and will cause severe photodamage to self-organized systems. (AU)

• Processo FAPESP: 08/07240-9 - Monocamadas e bicamadas lipídicas: adsorção de azul de metileno e fotossensibilização
• Beneficiário: Thaís Fernandes Schmidt
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 13/08166-5 - Química em interfaces: interações de fármacos, peptídios e enzimas com membranas modelos
• Beneficiário: Iolanda Midea Cuccovia
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 12/50680-5 - Fotossensibilização nas ciências da vida
• Beneficiário: Mauricio da Silva Baptista
• Modalidade de apoio: Auxílio à Pesquisa - Temático