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Recently, use of novel synthetic cannabinoids has increased greatly despite worldwide efforts to regulate these drugs. XLR-11 ((1-[5'-fluoropentyl]indol-3-yl)-(2,2,3,3-tetramethylcyclopropyl)methanone), a fluorinated synthetic cannabinoid with a tetramethylcyclopropyl moiety, has been frequently abused since 2012. XLR-11 produces a number of metabolites in common with its non-fluorinated parent analogue, UR-144 ((1-pentylindol-3-yl)-(2,2,3,3-tetramethylcyclopropyl)methanone). Therefore, it is essential to develop effective urinary markers to distinguish between these drugs. In this study, we investigated the metabolic profile of authentic human urine specimens from suspected users of XLR-11 using liquid chromatography-quadrupole time-of-flight mass spectrometry. Furthermore, we quantified four potential XLR-11 metabolites by using commercially available reference standards. In vitro metabolism of XLR-11 and UR-144 using human liver microsomes was also investigated to compare patterns of production of hydroxypentyl metabolites. Urine samples were prepared with and without enzymatic hydrolysis, and subjected to solid-phase extraction. We identified 19 metabolites generated by oxidative defluorination, hydroxylation, carboxylation, dehydrogenation, glucuronidation, and combinations of these reactions. Among the identified metabolites, 12 were generated from a cyclopropyl ring-opened XLR-11 degradation product formed during smoking. The XLR-11 metabolite with a hydroxylated 2,4-dimethylpent-1-ene moiety was detected in most specimens after hydrolysis and could be utilized as a specific marker for XLR-11 intake. Quantitative results showed that the concentration ratio of 5- and 4-hydroxypentyl metabolites should also be considered as a useful marker for differentiating between the abuse of XLR-11 and UR-144.

Hyperhomocysteinemia is an independent risk factor for several cardiovascular diseases. The use of vitamins to modulate homocysteine metabolism substantially lowers the risk by reducing plasma homocysteine levels. In this study, we evaluated the effects of l-serine and related amino acids on homocysteine-induced endoplasmic reticulum (ER) stress and endothelial cell damage using EA.hy926 human endothelial cells. Homocysteine treatment decreased cell viability and increased apoptosis, which were reversed by cotreatment with l-serine. l-Serine inhibited homocysteine-induced ER stress as verified by decreased glucose-regulated protein 78kDa (GRP78) and C/EBP homologous protein (CHOP) expression as well as X-box binding protein 1 (xbp1) mRNA splicing. The effects of l-serine on homocysteine-induced ER stress are not attributed to intracellular homocysteine metabolism, but instead to decreased homocysteine uptake. Glycine exerted effects on homocysteine-induced ER stress, apoptosis, and cell viability that were comparable to those of l-serine. Although glycine did not affect homocysteine uptake or export, coincubation of homocysteine with glycine for 24h reduced the intracellular concentration of homocysteine. Taken together, l-serine and glycine cause homocysteine-induced endothelial cell damage by reducing the level of intracellular homocysteine. l-Serine acts by competitively inhibiting homocysteine uptake in the cells. However, the mechanism(s) by which glycine lowers homocysteine levels are unclear.

Lysergic acid diethylamide (LSD) is administered in low dosages, which makes its detection in biological matrices a major challenge in forensic toxicology. In this study, two sensitive and reliable methods based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) were established and validated for the simultaneous determination of LSD and its metabolite, 2-oxo-3-hydroxy-LSD (O-H-LSD), in hair and urine. Target analytes in hair were extracted using methanol at 38°C for 15h and analyzed by LC-MS/MS. For urine sample preparation, liquid-liquid extraction was performed. Limits of detection (LODs) in hair were 0.25pg/mg for LSD and 0.5pg/mg for O-H-LSD. In urine, LODs were 0.01 and 0.025ng/ml for LSD and O-H-LSD, respectively. Method validation results showed good linearity and acceptable precision and accuracy. The developed methods were applied to authentic specimens from two legal cases of LSD ingestion, and allowed identification and quantification of LSD and O-H-LSD in the specimens. In the two cases, LSD concentrations in hair were 1.27 and 0.95pg/mg; O-H-LSD was detected in one case, but its concentration was below the limit of quantification. In urine samples collected from the two suspects 8 and 3h after ingestion, LSD concentrations were 0.48 and 2.70ng/ml, respectively, while O-H-LSD concentrations were 4.19 and 25.2ng/ml, respectively. These methods can be used for documenting LSD intake in clinical and forensic settings.