natural terpenes: self assembly and membrane partitioning

TURINA AV,; JULIO ALBERTO ZYGADLO; PERILLO MA,

Biophysical Chemistry

Elsevier

Lugar: Internacional; Año: 2006 vol. 122 p. 101 - 113

0301-4622

Monoterpenes (MTs) are highly hydrophobic substances present in essential oils. They cover a wide spectrum of biological effects with a membrane interaction as a common point. Here we studied the surface activity of camphor, cinele, thymol, menthol and geraniol, and their ability toreach and incorporate into model membranes affecting some features of their dynamic organization. All the MTs studed self aggregated in water with critical micellar concentrations (CMC) between 3 and 8 mM. Their octanol-water and membrane –wter partition coefficients wer correlatedwith one another. They all penetrated in monomolecular layers of dipalmitoiyl phosphatidylcholine at the air water interface, even at surface pressures (p) abore the equilibrium lateral pressure of bilayers, thymol exhibited the highest (61.3 mN/m) and camphor the lowest (37mN/m) p cut-off value. They affected the self aggregation of Triton X100 increasing its CMC from 0.16 mM inthe absence of MTs up to 0.68 mM (e.g. for geraniol), and the topology of sPC vesicles, increasing its surface  curvature, suggesting their loction at the polar head group region of the membrane. The latter was supported by their ability to increase differentially the polarity of the membrane environment sensed by two electrochromic dyes. Dipole moment values (between 1.224 and 2.523 D) and solvation areas (between 80 and 97 A) were calculated from their energy minimized structures. The relative contribution of each experimental, theoretical and structyural property to determine MTs´effects on membrane dynamics wre evaluated by a principal component analysis.