Alkylamides from Echinacea Are a New Class of Cannabinomimetics

Abstract

Alkylamides (alkamides) from Echinacea modulate tumor necrosis factor ␣ mRNA expression in human monocytes/macrophages via the cannabinoid type 2 (CB 2 ) receptor (Gertsch, J., Schoop, R., Kuenzle, U., and Suter, A. (2004) FEBS Lett. 577, 563-569). Here we show that the alkylamides dodeca-2E,4E,8Z,10Z-tetraenoic acid isobutylamide (A1) and dodeca-2E,4E-dienoic acid isobutylamide (A2) bind to the CB 2 receptor more strongly than the endogenous cannabinoids. The K i values of A1 and A2 (CB 2 ϳ60 nM; CB 1 >1500 nM) were determined by displacement of the synthetic high affinity cannabinoid ligand [ 3 H]CP-55,940. Molecular modeling suggests that alkylamides bind in the solvent-accessible cavity in CB 2 , directed by H-bonding and -interactions. In a screen with 49 other pharmacologically relevant receptors, it could be shown that A1 and A2 specifically bind to CB 2 and CB 1 . A1 and A2 elevated total intracellular Ca 2؉ in CB 2 -positive but not in CB 2 -negative promyelocytic HL60 cells, an effect that was inhibited by the CB 2 antagonist SR144528. At 50 nM, A1, A2, and the endogenous cannabinoid anandamide (CB 2 K i >200 nM) up-regulated constitutive interleukin (IL)-6 expression in human whole blood in a seemingly CB 2 -dependent manner. A1, A2, anandamide, the CB 2 antagonist SR144528 (K i <10 nM), and also the non-CB 2 -binding alkylamide undeca-2E-ene,8,10-diynoic acid isobutylamide all significantly inhibited lipopolysaccharide-induced tumor necrosis factor ␣, IL-1␤, and IL-12p70 expression (5-500 nM) in a CB 2 -independent manner. Alkylamides and anandamide also showed weak differential effects on anti-CD3-versus anti-CD28-stimulated cytokine expression in human whole blood. Overall, alkylamides, anandamide, and SR144528 potently inhibited lipopolysaccharide-induced inflammation in human whole blood and exerted modulatory effects on cytokine expression, but these effects are not exclusively related to CB 2 binding.

Alkamide production from hairy root cultures of Echinacea

“…Both of these alkamides are of special interest. Fractions of alkamide 2 had the highest inhibition of cyclooxygenase-1 and -2, and alkamide 8 exhibited a very strong affinity for the CB 2 cannabinoid receptors (Raduner et al 2006;Woelkart and Bauer 2007). Binding to CB 2 receptors is considered a possible mode of action for the immunomodulatory effects of the alkamides of Echinacea.…”

“…Alkamides trigger enhanced anti-inflammatory activity and immunostimulatory responses (Chen et al 2005;Woelkart et al 2006). Alkamides from Echinacea modulated a therapeutic response via the CB 2 -specific cannabinoid receptor and inhibited lipopolysaccharide-induced inflammation in human whole blood (Raduner et al 2006;Woelkart and Bauer 2007).…”

Anti-inflammatory activities ofEchinaceaextracts do not correlate with traditional marker components

“…A number of Echinacea marker compounds have been characterized, including polysaccharides, caffeic acid derivatives (CADs) and alkylamides (Bauer, 1998;Binns et al, 2002), and these have all been shown to possess infectionrelated bio-activities in various tests in vitro and in vivo, including immune-modulating activities, anti-viral activities, and antibiotic activities (Burger et al, 1997;Bauer, 1998;Rininger et al, 2000;Goel et al, 2002;Merali et al, 2003;Gertsch et al, 2004;Vimalanathan et al, 2005;Hudson et al, 2005;Raduner et al, 2006;Sharma et al, 2006;LaLone et al, 2007).…”

An ethnopharmacological survey conducted in the Bolivian Amazon, and identification of N-alkylamides and lignans from Lepidium meyenii and Heliopsis helianthoides var. scabra with effects on the central nervous system

“…65,74 For instance, NAAs seem to play a major role in the bioactivity of the widely used medicinal plants of the Echinacea genus. 35,[65][66][67][68] The immunomodulatory Echinacea alkylamides dodeca-2E,4E,8Z,10Z-tetraenoic acid isobutylamide ( Figure 2) and dodeca-2E,4E-dienoic acid isobutylamide bind to the cannabinoid-2 (CB 2 ) receptor more strongly than the endogenous cannabinoids. 68 While the interactions of Echinacea NAAs with CB receptors have been studied in more detail, ECS-interacting NAAs from other plants have been described only recently.…”

“…35,[65][66][67][68] The immunomodulatory Echinacea alkylamides dodeca-2E,4E,8Z,10Z-tetraenoic acid isobutylamide ( Figure 2) and dodeca-2E,4E-dienoic acid isobutylamide bind to the cannabinoid-2 (CB 2 ) receptor more strongly than the endogenous cannabinoids. 68 While the interactions of Echinacea NAAs with CB receptors have been studied in more detail, ECS-interacting NAAs from other plants have been described only recently. 72,73,75,76 The assumption that NAAs may interfere with the ECS due to their structural similarity to endocannabinoids such as anandamide (N-arachidonoylethanolamide, AEA) and palmitoylethanolamide 35 is intuitive, but the confirmation of this assumption is hampered by the lack of structure -activity relationship (SAR) data.…”