UR-144

Abstract: Four herbal incense products were seized from suspected drug abusers in Korea. The major ingredients in the herbal incense samples were purified, and their structures were elucidated using gas chromatography–electron ionization–mass spectrometry (GC–EI–MS), liquid chromatography–time-of-flight–mass spectrometry (LC–TOF–MS), and 1D and 2D nuclear magnetic resonance (NMR) spectroscopy. As a result, ingredients in the herbal incense were identified as (1-pentylindol-3-yl)-(2,2,3,3-tetramethylcyclopropyl)methanone and its 5-pentyl fluorinated analog [1-(5-fluoropentyl)indol-3-yl]-(2,2,3,3-tetramethylcyclopropyl)methanone. The former is being sold via the Internet as a "research chemical" named UR-144, and the latter is sold as 5F-UR-144. UR-144 is a selective full agonist of CB2 cannabinoid receptor, and was first developed by Abbott Laboratories as an analgesic. It exhibits analgesic activity against both neuropathic and inflammatory pain associated mainly with the CB2 receptor, but shows less psychotropic effects associated with the CB1 receptor. Fluorination of the N-pentyl side chain of cannabimimetic compounds increases their cannabinoid receptor affinity such as with AM-2201, which shows both increased analgesic and psychotropic effects simultaneously. UR-144 and 5F-UR-144 can be classified as research chemicals based on their analgesic effects, but in practice are abused as psychotropic agents and can cause unexpected toxic effects. Thus, the trade and diversion of these chemicals should be monitored carefully for possible abuse. To our knowledge, this is the first report disclosing cyclopropylcarbonylindoles in herbal products.

Abstract: Drug abusers most often smoke 'herbal incense' as a cigarette or inhale it using a smoking tool. Smoking may cause pyrolysis of the drug and produce decomposed products of which biological effect has never been investigated. The synthetic cannabinoid UR-144 is known to undergo thermal degradation, giving a ring-opened isomer, so-called UR-144 degradant. The present study demonstrates by using UR-144 as a model drug that the smoke of burned UR-144 contains the UR-144 degradant. The UR-144 degradant showed approximately four fold higher agonist activity to human CB1 receptor and augmented hypothermic and akinetic actions in mice compared to UR-144. These results indicate that smoking behavior may increase psychological actions of the certain synthetic cannabinoids.

Abstract: Synthetic cannabinoid (SC) designer drugs featuring bioisosteric fluorine substitution are identified by forensic chemists and toxicologists with increasing frequency. Although terminal fluorination of N-pentyl indole SCs is sometimes known to improve cannabinoid type 1 (CB1) receptor binding affinity, little is known of the effects of fluorination on functional activity of SCs. This study explores the in vitro functional activities of SC designer drugs JWH-018, UR-144, PB-22, and APICA, and their respective terminally fluorinated analogues AM-2201, XLR-11, 5F-PB-22, and STS-135 at human CB1 and CB2 receptors using a FLIPR membrane potential assay. All compounds demonstrated agonist activity at CB1 (EC50 = 2.8–1959 nM) and CB2 (EC50 = 6.5–206 nM) receptors, with the fluorinated analogues generally showing increased CB1 receptor potency (∼2–5 times). Additionally, the cannabimimetic activities and relative potencies of JWH-018, AM-2201, UR-144, XLR-11, PB-22, 5F-PB-22, APICA, and STS-135 in vivo were evalu...

Abstract: Several 3-acylindoles with high affinity for the CB(2) cannabinoid receptor and selectivity over the CB(1) receptor have been prepared. A variety of 3-acyl substituents were investigated, and the tetramethylcyclopropyl group was found to lead to high affinity CB(2) agonists (5, 16). Substitution at the N1-indole position was then examined. A series of aminoalkylindoles was prepared and several substituted aminoethyl derivatives were active (23-27, 5) at the CB(2) receptor. A study of N1 nonaromatic side chain variants provided potent agonists at the CB(2) receptor (16, 35-41, 44-47, 49-54, and 57-58). Several polar side chains (alcohols, oxazolidinone) were well-tolerated for CB(2) receptor activity (41, 50), while others (amide, acid) led to weaker or inactive compounds (55 and 56). N1 aromatic side chains also afforded several high affinity CB(2) receptor agonists (61, 63, 65, and 69) but were generally less potent in an in vitro CB(2) functional assay than were nonaromatic side chain analogues.