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Natural terpenes: self-assembly and membrane partitioning.
A del V Turina1, M V Nolan, J A Zygadlo
1Biofísica-Química, Departamento de Química, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Av. Vélez Sarsfield 1611, 5016 Córdoba, Argentina.
Biophysical Chemistry
|March 28, 2006
Summary
Monoterpenes (MTs) self-aggregate and interact with model membranes. These compounds alter membrane properties, influencing dynamic organization and polarity, with their effects predictable by structural and experimental properties.
Area of Science:
- Biochemistry and Biophysics
- Membrane Biophysics
- Natural Products Chemistry
Background:
- Monoterpenes (MTs) are hydrophobic compounds found in essential oils with diverse biological effects.
- Membrane interaction is a common mechanism underlying MTs' biological activities.
Purpose of the Study:
- To investigate the surface activity and membrane interaction of five monoterpenes: camphor, cineole, thymol, menthol, and geraniol.
- To determine how these MTs affect model membrane organization, dynamics, and polarity.
Main Methods:
- Measurement of critical micellar concentrations (CMC) and partition coefficients.
- Analysis of monomolecular layer penetration at the air-water interface.
- Investigation of effects on Triton X-100 self-aggregation and vesicle topology.
- Assessment of membrane polarity changes using electrochromic dyes.
- Calculation of dipole moments and solvation areas from energy-minimized structures.
- Principal component analysis to correlate properties with effects.
Main Results:
- All studied MTs self-aggregated in water with CMCs between 3-8 µM.
- MTs penetrated dipalmitoyl-phosphatidylcholine monolayers, with thymol showing the highest surface pressure cutoff.
- MTs increased Triton X-100's CMC and altered vesicle surface curvature, suggesting interaction with the polar head group region.
- MTs differentially increased membrane polarity and their effects were predictable via principal component analysis.
Conclusions:
- Monoterpenes exhibit significant surface activity and readily incorporate into model membranes.
- Their interaction influences membrane dynamics, organization, and local polarity.
- The study provides insights into the physicochemical basis of monoterpene-membrane interactions.