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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

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

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de Souza, R. M. ; Siani, P. ; Schmidt, T. F. ; Itri, R. ; Dias, L. G.
Total Authors: 5
Document type: Journal article
Source: Journal of Physical Chemistry B; v. 121, n. 36, p. 8512-8522, SEP 14 2017.
Web of Science Citations: 1

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)

FAPESP's process: 13/08166-5 - Interfacial chemistry: drugs, peptides and ezymes interactions with membrane models
Grantee:Iolanda Midea Cuccovia
Support type: Research Projects - Thematic Grants
FAPESP's process: 08/07240-9 - Lipid model membrane: methylene blue adsorption and photosensitization
Grantee:Thaís Fernandes Schmidt
Support type: Scholarships in Brazil - Doctorate
FAPESP's process: 12/50680-5 - Photosensitization in life sciences
Grantee:Mauricio da Silva Baptista
Support type: Research Projects - Thematic Grants