The Endocannabinoid System as a Target for Alkamides from Echinacea angustifolia Roots

Abstract

Alkamides are the major lipophilic constituents of Echinacea angustifolia roots. Due to their structural similarity with anandamide, we have evaluated their ability to bind to rodent cannabinoid receptors CB1 and CB2 by a standard receptor binding assay using [³H]CP-55,940 as a radioligand. The alkamides exhibited selective affinity especially to CB2 receptors and can therefore be considered as CB ligands. Most of the alkamides showed good metabolic stability as indicated by the similarity between affinity to CB1 determined in the presence/absence of the protease inhibitor PMSF. It is suggested that CB2 interactions may be the molecular mode of action of Echinacea alkamides as immunomodulators.

Abbreviations

CB1:cannabinoid receptor 1

CB2:cannabinoid receptor 2

FAAH:Fatty acid amidohydrolase

PMSF:phenylmethanesulfonylfluoride

AEA:arachidonylethanolamide, anandamide

AA:arachidonic acid

IL:interleukin

MCP:monocyte chemoattractant protein

BSA:bovine serum albumin

TNF-α:tumor necrosis factor-alpha

MAPK:mitogen-activated protein kinase

JNK:jun N-terminal kinase

cAMP:cyclic adenosine monophosphate

CREB-1:responsive element binding protein-1

ATF-2:activating transcription factor-2

NF-κB:nuclear factor kappa B

Tris:Tris-(hydroxymethyl)-amino-methane

CP55940:(-)-cis-3-[2-hydroxy-4(1,1-dimethyl-heptyl)phenyl]-trans-4-(3-hydroxypropyl)cyclohexanol

References

• 1 Bauer R, Wagner H. Echinacea species as potential immunostimulatory drugs. In: Wagner H, Farnsworth NR, editors Economic and Medicinal Plant Research. London; Academic Press 1991: pp 253-321
• 2 Bauer R. Chemistry, analysis and immunological investigations of Echinacea phytopharmaceuticals. In: Wagner H, editor Immunomodulatory Agents from Plants Basel; Birkhäuser Verlag 1999: pp 41-88
• 3 Bauer R, Remiger P, Wagner H. Alkamides from the roots of Echinacea angustifolia .  Phytochemistry. 1989;  28 505-8
• 4 Gertsch J, Schoop R, Kuenzle U, Suter A. Echinacea alkylamides modulate TNF-α gene expression via cannabinoid receptor CB2 and multiple signal transduction pathways.  FEBS Lett. 2004;  577 563-9
• 5 Remiger P. Zur Chemie und Immunologie neuer Alkylamide und anderer Inhaltsstoffe aus Echinacea purpurea, Echinacea angustifolia und Echinacea pallida . PhD thesis University of Munich; 1988
• 6 Lan R, Liu Q, Fan P, Lin S, Fernando S R, McCallion D. et al . Structure-activity relationships of pyrazole derivatives as cannabinoid receptor antagonists.  J Med Chem. 1999;  42 769-76
• 7 Cheng Y C, Prusoff W H. Relationship between the inhibition constant (Ki) and the concentration of inhibitor which causes 50 per cent inhibiton (IC₅₀) of an enzymatic reaction.  Biochem Pharmacol. 1973;  22 3099-108
• 8 Lang W, Qin C, Hill W A, Lin S, Khanolkar A D, Makriyannis A. High-performance liquid chromatographic determination of anandamide amidase activity in rat brain microsomes.  Anal Biochem. 1996;  238 40-5
• 9 Pertwee R G, Fernando S R, Griffin G, Abadji V, Makriyannis A. Effect of phenylmethylsulphonyl fluoride on the potency of anandamide as an inhibitor of electrically evoked contractions in two isolated tissue preparations.  Eur J Pharmacol. 1995;  272 73-8
• 10 Matias I, Pochard P, Orlando P, Salzet M, Pestel J, Di Marzo V. Presence and regulation of the endocannabinoid system in human dendritic cells.  Eur J Biochem. 2002;  269 3771-8
• 11 Pertwee R G. Pharmacology of cannabinoid CB1 and CB2 receptors.  Pharmacol Ther. 1997;  74 129-80
• 12 Klein T W, Newton C, Friedman H. Cannabinoid receptors and immunity.  Immunol Today. 1998;  19 373-81
• 13 Goutopoulos A, Makriyannis A. From cannabis to cannabinergics new therapeutic opportunities.  Pharmacol Ther. 2002;  95 103-17
• 14 Lin S, Khanolkar A D, Fan P, Goutopoulos A, Qin C, Paphadjis D. et al . Novel analogues of arachidonylethanolamide (anandamide): Affinities for the CB1 and CB2 cannabinoid receptors and metabolic stability.  J Med Chem. 1998;  41 5353-61
• 15 Jbilo O, Derocq J M, Segui M, Fur G L, Casellas P. Stimulation of peripheral cannabinoid receptor CB2 induces MCP-1 and IL-8 gene expression in human promyelocytic cell line HL60.  FEBS Lett. 1999;  448 273-7
• 16 Sugiura T, Oka S, Gokoh M, Kishimoto S, Waku K. New perspectives in the studies on endocannabinoid and cannabis: 2-arachidonoylglycerol as a possible novel mediator of inflammation.  J Pharmacol Sci. 2004;  96 367-75
• 17 Kishimoto S, Kobayashi Y, Oka S, Gokoh M, Waku K, Sugiura T. 2-Arachidonoylglycerol, an endogenous cannabinoid receptor ligand, induces accelerated production of chemokines in HL-60 cells.  J Biochem. 2004;  135 4517-24
• 18 Chang Y H, Lee S T, Lin W W. Effects of cannabinoids on LPS-stimulated inflammatory mediator release from macrophages: involvement of eicosanoids.  J Cell Biochem. 2001;  81 715-23
• 19 Gallily R, Breuer A, Mechoulam R. 2-Arachidonylglycerol, an endogenous cannabinoid, inhibits tumor necrosis factor-α production in murine macrophages, and in mice.  Eur J Pharmacol. 2000;  406 R5-R7
• 20 Facchinetti F, Del Giudice E, Furegato S, Passerotto M, Leon A. Cannabinoids ablate release of TNFα in rat microglial cells stimulated with lipopolysaccharide.  Glia. 2003;  41 161-8
• 21 Klegeris A, Bissonnette C J, McGeer P L. Reduction of human monocytic cell neurotoxicity and cytokine secretion by ligands of the cannabinoid-type CB2 receptor.  Br J Pharmacol. 2003;  139 775-86
• 22 Parolaro D, Massi P, Rubino T, Monti E. Endocannabinoids in the immune system and cancer.  Prostaglandins Leukot Essent Fatty Acids. 2002;  66 319-32
• 23 Turner R B. The treatment of rhinovirus infections: progress and potential.  Antiviral Res. 2001;  49 1-14
• 24 Woelkart K, Koidl C, Grisold A, Gangemi J D, Turner R B, Marth E, Bauer R. Bioavailability and pharmacokinetics of alkamides from the roots of Echinacea angustifolia in humans. J Clin Pharmacol 2005 45: 683-9