PurposeIn the present study we characterized a series of synthetic cannabinoids containing various heterocyclic scaffolds that had been identified as constituents of “Spice”, a preparation sold on the illicit drug market. All compounds were further investigated as potential ligands of the orphan receptors GPR18 and GPR55 that interact with some cannabinoids.MethodsThe compounds were studied in radioligand binding assays to determine their affinity for human cannabinoid CB1 and CB2 receptors expressed in CHO cells, and in cAMP accumulation assays to study their functionality.ResultsStructure-activity relationships were analyzed. The most potent CB1 receptor agonist of the present series MDMB-FUBINACA (12) (Ki = 98.5 pM) was docked into the human CB1 receptor structure, and a plausible binding mode was identified showing high similarity with that of the co-crystallized THC derivatives. MDMB-CHMCZCA (41) displayed a unique profile acting as a full agonist at the CB1 receptor subtype, but blocking the CB2 receptor completely. Only a few weakly potent antagonists of GPR18 and GPR55 were identified, and thus all compounds showed high CB receptor selectivity, mostly interacting with both subtypes, CB1 and CB2.ConclusionsThese results will be useful to assess the compounds’ toxicological risks and to guide legislation. Further studies on 41 are warranted.Electronic supplementary materialThe online version of this article (10.1007/s11419-018-0415-z) contains supplementary material, which is available to authorized users.

In recent years, many synthetic cannabinoid (CB) receptor agonists have appeared on the market as constituents of herbal incense mixtures known as “spice”. Contrary to the declared use, they are perorally consumed as a replacement for marijuana to get “high”. In many cases, detailed information on the physicochemical and pharmacological properties of the synthetic compounds found in spice preparations is lacking. We have now evaluated a large series of heterocyclic compounds, 1,3-disubstituted indole and 2-azaindole derivatives known or assumed to be CB1 receptor agonists, many of which have previously been identified in forensic samples. The mainly observed structural variations to circumvent restriction by law were bioisosteric exchanges of functional groups in known CB1 agonists. We analyzed the structure-activity relationships of compounds at human CB1 and CB2 receptors based on affinities obtained in radioligand binding studies, and determined their efficacy in cAMP accumulation assays. Moreover, we investigated the activities of the compounds at the orphan G protein-coupled receptors GPR18 and GPR55 both of which are known to interact with cannabinoids. Most of the investigated compounds behaved as potent full agonists of CB1 and CB2 receptors with affinities in the low nanomolar to subnanomolar concentration range. Some compounds were moderately potent GPR55 antagonists, while none interacted with GPR18. Most derivatives were predicted to cross the blood–brain barrier as determined by bioinformatics tools. These data are useful for assessing synthetic cannabinoids and will be helpful for predicting pharmacological properties of novel compounds that appear on the illicit drug market.Electronic supplementary materialThe online version of this article (doi:10.1007/s11419-016-0320-2) contains supplementary material, which is available to authorized users.

Gamma‐hydroxybutyric acid (GHB) is a sedative drug used in drug‐facilitated crimes. Its detection window is very short. GHB undergoes intensive phase I metabolism to organic acids (glycolic acid, succinic acid, dihydroxybutyric acids). These could be potential analytical targets to broaden the detection window. The aim of the present study was to enable the detection of endogenous levels of these metabolites in biological samples (blood and urine). A gas chromatographic–mass spectrometric method using liquid–liquid extraction and derivatization with N‐methyl‐N‐tri‐methylsilyltrifluoracetamide was developed for the quantification. Validation results were consistent with international guidelines, and the method was able to quantify endogenous levels of the substances in both urine and blood. Endogenous concentrations were shown to be <0.03–4.92 mg/L for glycolic acid, <0.03–1.28 mg/L for GHB, <0.28–18.1 mg/L for succinic acid, <0.12–1.38 mg/L for 2,4‐dihydroxybutyric acid, and <0.13–2.59 mg/L for 3,4‐dihydroxybutyric acid in serum samples of 101 volunteers. Urinary endogenous concentrations were shown to be 1.30–400 mg/L for glycolic acid, <0.03–1.94 mg/L for GHB, 1.17–2.73 mg/L for succinic acid, 0.72–26.2 mg/L for 2,4‐dihydroxybutyric acid, and 1.88–122 mg/L for 3,4‐dihydroxybutyric acid in urine samples of 132 volunteers. These endogenous concentrations represent a basis to which concentrations after the intake of GHB can be compared to in order to prove the intake of this substance.

The detection of diabetic metabolism disorders raises problems in forensic practice and sudden death with a subsequent negative autopsy finding is a common problem. In the case of an unclear hypoglycaemia, the detection of oral antidiabetics allows the differentiation of hypoglycaemia due to oral antidiabetics from that due to other reasons (insulin-induced, insulinoma). The development of an electrospray ionisation (ESI) liquid chromatography-tandem mass spectrometry (LC-MS/MS) procedure for the simultaneous identification and quantification of oral antidiabetics of the sulfonylurea, the glinide, the thiazolidinedione and the gliptin types in human plasma is desired. The following analytes were included: glimepiride, glibenclamide, gliquidone, glibornuride, glisoxepide, glipizide and gliclazide (sulfonylurea type), nateglinide and repaglinide (glinide type), rosiglitazone and pioglitazone (thiazolidinedione type) and the dipeptidyl peptidase inhibitors vildagliptin, sitagliptin and saxagliptin. After a liquid-liquid extraction with tert-butyl methyl ether at two pHs, the oral antidiabetics were separated with fast gradient elution over a C(8) column. Identification of the oral antidiabetics was achieved by two specific ion transitions of each analyte in multiple reaction monitoring mode. Quantification was performed by referring the most intense ion transition peak areas to peak areas of the ion transitions of deuterated oral antidiabetics (hydroxytolbutamide-d(9) for the sulfonylureas, repaglinide-ethyl-d(5) for the glinides, pioglitazone-d(4) for the thiazolidinediones and vildagliptin-d(3) for the gliptins). The assay was validated according to international guidelines. The LC-MS/MS assay allows the simultaneous identification of 14 oral antidiabetics and quantification of 11 oral antidiabetics in plasma in the ESI mode in a single run. Linearity is shown up to overdose concentrations. The limits of detection with a signal-noise-ratio greater than 3 were below 1 ng/ml for all analytes. Recoveries ranged from 78 to 105%; for vildagliptin and saxagliptin recoveries were worse (45%) owing to their hydrophilic character. Intraday and interday precision and accuracy were below 20% for 11 drugs at three concentrations. For the gliptins, several validation parameters were out of range and, therefore, quantitatively this method is inappropriate.

The bioassays have the potential to serve as a first-line screening tool for (synthetic) cannabinoid activity in serum or plasma and may complement conventional analytical assays and/or precede analytical (mass spectrometry based) confirmation.