The antinociceptive triterpene β‐amyrin inhibits 2‐arachidonoylglycerol (2‐AG) hydrolysis without directly targeting cannabinoid receptors

Abstract

BACKGROUND AND PURPOSEPharmacological activation of cannabinoid CB1 and CB2 receptors is a therapeutic strategy to treat chronic and inflammatory pain. It was recently reported that a mixture of natural triterpenes a-and b-amyrin bound selectively to CB1 receptors with a subnanomolar Ki value (133 pM). Orally administered a/b-amyrin inhibited inflammatory and persistent neuropathic pain in mice through both CB1 and CB2 receptors. Here, we investigated effects of amyrins on the major components of the endocannabinoid system. EXPERIMENTAL APPROACHWe measured CB receptor binding interactions of a-and b-amyrin in validated binding assays using hCB1 and hCB2 transfected CHO-K1 cells. Effects on endocannabinoid transport in U937 cells and breakdown using homogenates of BV2 cells and pig brain, as well as purified enzymes, were also studied. KEY RESULTSThere was no binding of either a-or b-amyrin to hCB receptors in our assays (Ki > 10 mM). The triterpene b-amyrin potently inhibited 2-arachidonoyl glycerol (2-AG) hydrolysis in pig brain homogenates, but not that of anandamide. Although b-amyrin only weakly inhibited purified human monoacylglycerol lipase (MAGL), it also inhibited a,b-hydrolases and more potently inhibited 2-AG breakdown than a-amyrin and the MAGL inhibitor pristimerin in BV2 cell and pig brain homogenates. CONCLUSIONS AND IMPLICATIONSWe propose that b-amyrin exerts its analgesic and anti-inflammatory pharmacological effects via indirect cannabimimetic mechanisms by inhibiting the degradation of the endocannabinoid 2-AG without interacting directly with CB receptors. Triterpenoids appear to offer a very broad and largely unexplored scaffold for inhibitors of the enzymic degradation of 2-AG. LINKED ARTICLESThis article is part of a themed section on Cannabinoids. To view the other articles in this section visit http://dx

Biochemical and pharmacological characterization of human α/β-hydrolase domain containing 6 (ABHD6) and 12 (ABHD12)

“…Finally, the triterpene pristimerin, which was previously shown to reversibly inhibit MAGL (IC 50 , 93 nM) ( 42 ), also inhibited hABHD6 (IC 50 , 1.4 µM), whereas hABHD12 was resistant to this compound. These fi ndings, together with the recent discovery of similar inhibitory action of other triterpenoids ( 43 ), should encourage further studies to explore more thoroughly this family of naturally occurring compounds as reversible inhibitors of enzymatic 2-AG degradation.…”

“…By applying a sensitive fl uorescent assay to kinetically monitor glycerol production "on line," we delineate here the substrate profi les of human ABHD6 and ABHD12 in comparison with MAGL. After transient transfections in HEK293 cells, the three hydrolases degraded a by guest, on May 9, 2018 www.jlr.org Downloaded from .html http://www.jlr.org/content/suppl/2012/09/11/jlr.M030411.DC1 Supplemental Material can be found at:…”

Identification and Quantification of a New Family of Peptide Endocannabinoids (Pepcans) Showing Negative Allosteric Modulation at CB1 Receptors

“…Altogether, these data support the negative allosteric mechanism of Pepcan-12 at CB 1 receptors. To ensure that Pepcan-12 does not indirectly affect CB 1 receptors through modulation of AEA and 2-AG levels, we measured the effect of Pepcan-12 on AEA and 2-AG hydrolysis in pig brain homogenates, as previously described (28). As shown in Fig.…”

Update: Biological and Chemical Aspects of Senna spectabilis

“…3, 2017 inflammatory, antinociceptive, antioxidant, antipruritic, antibacterial and gastro-hepatoprotective properties. [52][53][54][55][56][57][58][59] More recently, Jeon et al 60 also showed that β-amyrin improves general sleep behavior induced by pentobarbital model, through the activation of Gamma-AminoButyric Acid (GABAergic) neurotransmission system in the brain.…”