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Previous issue date: 2014-04-25 === Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES === The interactions of terpenes with membranes of erythrocyte, fibroblasts, stratum corneum and the model membranes of 1,2-dipalmitoylsn -glycero-3-phosphocholine were investigated by using the the electron paramagnetic resonance and fluorescence spectroscopic of lipophilic
probes. It has been shown that when added at high concentrations to systems having a high
lipid/solvent ratio, terpenes such as 1,8-cineol, α-terpineol, (+)-limonene and nerolidol are able
to self-stabilize in molecular aggregates which can extract the bilayers lipids. Studies on the
hemolytic and cytotoxic potential of various terpenes showed that cell damage caused by these
molecules are concentration dependent and that among the studied terpenes, nerolidol and
α-terpineol are the most hemolytic and cytotoxic, while (+)-limonene and 1,8-cineole are the
least hemolytic and cytotoxic. However, the low correlation between these two tests indicates
that the processes involved in each case are not completely dependent. It was also shown that
once embedded in the membrane, terpenes increase the fluidity of lipid bilayers and decrease
the temperature of the main phase transition. Differences between increased fluidity promoted
by sesquiterpene nerolidol and all monoterpenes studied were observed. Meanwhile, in a comparison of the effect of the monoterpenes studied, no significant differences in their ability to
increase membrane fluidity were detected. Furthermore, it was demonstrated by using confocal
and atomic force microscopy and fluorescence spectroscopy that the 1,2-distearoylsn -glycero-3-(Aurora nanoparticles) is better incorporated in lipid membranes under fluid phase and that
the addition of 0.1% of these conjugated nanoparticles do not produces large variations in
membrane fluidity and no causes substantial morphological changes of lipid bilayers. === As intera¸c˜oes de terpenos com membranas de eritr´ocito, fibroblastos, estrato c´orneo e
membrana modelo composta de 1,2-dipalmitoil-sn -glicero-3-fosfocolina foram investigadas por
meio das espectroscopias de ressonˆancia paramagn´etica eletrˆ onica e de fluorescˆencia por meio
do uso de sondas lipof´ılicas. Foi poss´ıvel demonstrar que quando adicionados em altas concentra¸c˜oes `a sistemas que possuem uma alta rela¸c˜ao lip´ıdio/solvente, terpenos como o 1,8-cineol,
α-terpineol, (+)-limoneno e nerolidol s˜ao capazes de se estabilizar em agregados moleculares
capazes de extrair os lip´ıdios das bicamadas. Estudos sobre o potencial hemol´ıtico e citot´oxico
de v´arios terpenos demostraram que os danos celulares causados por estas mol´eculas s˜ao dependentes da concentra¸c˜ao e que dentre os terpenos estudados, nerolidol e terpineol s˜ao os mais
hemol´ıticos e citot´oxicos enquanto limoneno e cineol s˜ao os menos hemol´ıticos e citot´oxicos. Entretanto, a baixa correla¸c˜ao entre estes dois testes indica que os processos envolvidos em cada
caso n˜ao s˜ao totalmente dependentes. Ficou demonstrado ainda que uma vez incorporados nas
membranas, os terpenos aumentam a fluidez das bicamadas lip´ıdicas e diminuem a temperatura de sua transi¸c˜ao de fase principal. Diferen¸cas entre o aumento de fluidez promovido pelo
sesquiterpeno nerolidol e por todos os monoterpenos estudados foram verificadas. Contudo,
uma compara¸c˜ao entre o efeito dos monoterpenos estudados, n˜ao aponta para diferen¸cas significativas entre suas capacidades de aumento de fluidez. Al´em disso, foi demostrado atrav´es
das microscopias confocal e de for¸ca atˆomica e da espectroscopia de fluorescˆencia que a 1,2-distearoil-sn -glicero-3-(Nanopart´ıculas Aurora) ´e melhor incorporada em membranas lip´ıdicas
em fase fluida e que a adi¸c˜ao de 0,1% destas nanopart´ıculas conjugadas n˜ao produz grandes
varia¸c˜oes na fluidez e n˜ao provoca mudan¸cas morfol´ogicas substanciais das bicamadas lip´ıdicas.
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