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J Nat Prod. 2007 Jun;70(6):1010-5. Epub 2007 May 11.

Self-assembling cannabinomimetics: supramolecular structures of N-alkyl amides.

Author information

1
Department of Chemistry and Applied Biosciences, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Z├╝rich, Switzerland.

Abstract

Certain fatty acid N-alkyl amides from the medicinal plant Echinacea activate cannabinoid type-2 (CB2) receptors. In this study we show that the CB2-binding Echinacea constituents dodeca-2E,4E-dienoic acid isobutylamide (1) and dodeca-2E,4E,8Z,10Z-tetraenoic acid isobutylamide (2) form micelles in aqueous medium. In contrast, micelle formation is not observed for undeca-2E-ene-8,10-diynoic acid isobutylamide (3), which does not bind to CB2, or structurally related endogenous cannabinoids, such as arachidonoyl ethanolamine (anandamide). The critical micelle concentration (CMC) range of 1 and 2 was determined by fluorescence spectroscopy as 200-300 and 7400-10000 nM, respectively. The size of premicelle aggregates, micelles, and supermicelles was studied by dynamic light scattering. Microscopy images show that compound 1, but not 2, forms globular and rod-like supermicelles with radii of approximately 75 nm. The self-assembling N-alkyl amides partition between themselves and the CB2 receptor, and aggregation of N-alkyl amides thus determines their in vitro pharmacological effects. Molecular mechanics by Monte Carlo simulations of the aggregation process support the experimental data, suggesting that both 1 and 2 can readily aggregate into premicelles, but only 1 spontaneously assembles into larger aggregates. These findings have important implications for biological studies with this class of compounds.

PMID:
17497806
DOI:
10.1021/np060598+
[Indexed for MEDLINE]

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