Chemical Composition and Anticholinesterase Activity of the Essential Oil of Leaves and Flowers from the Ecuadorian Plant Lepechinia paniculata (Kunth) Epling

This work aimed to study the chemical composition, cholinesterase inhibitory activity, and enantiomeric analysis of the essential oil from the aerial parts (leaves and flowers) of the plant Lepechinia paniculata (Kunth) Epling from Ecuador. The essential oil (EO) was obtained through steam distillation. The chemical composition of the oil was evaluated by gas chromatography, coupled to mass spectrometry (GC–MS) and a flame ionization detector (GC-FID). The analyses led to the identification of 69 compounds in total, of which 40 were found in the leaves and 29 were found in the flowers of the plant. The major components found in the oil were 1,8-Cineole, β-Pinene, δ-3-Carene, α-Pinene, (E)-Caryophyllene, Guaiol, and β-Phellandrene. Flower essential oil showed interesting selective inhibitory activity against both enzymes AChE (28.2 ± 1.8 2 µg/mL) and BuChE (28.8 ± 1.5 µg/mL). By contrast, the EO of the leaves showed moderate mean inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), with IC50 values of 38.2 ± 2.9 µg/mL and 47.4 ± 2.3 µg/mL, respectively.

Enantiomeric analysis of clenbuterol in Chinese people by LC–MS/MS to distinguish doping abuse from meat contamination

Aim: Follow-up investigations are often required for clenbuterol-positive cases. A method to distinguish doping abuse from meat contamination was developed. Materials & methods: A total of 26 volunteers were recruited to ingest clenbuterol contaminated-pork and clenbuterol tablets. Results: For 20 volunteers, after ingestion of contaminated-pork, R-(-)/S-(+)-clenbuterol ratio was <1.0, while the value was >1.0 after taking clenbuterol tablets. However, after taking clenbuterol tablets, some ratio points of the other six volunteers were between 0.9 and 1.0. A case of an abnormal cold and fever, which returned to normal after recovery, was also reported firstly. Conclusion: A change in R-(-)/S-(+)-clenbuterol was reported in the Chinese population initially. A ratio of 0.9 was recommended in doping related cases for the Chinese population.

Quantification and Stereochemical Composition of R-(−) and S-(+)-Clenbuterol Enantiomers in Bovine Urine by Liquid Chromatography–Tandem Mass Spectrometry

Clenbuterol (4-amino-α-[(tert-butylamino)methyl]-3,5-dichlorobenzylalcohol) is a β2-adrenergic agonist. The consumption of meat contaminated with clenbuterol can lead to increased heart rate, blood pressure, anxiety, palpitations and skeletal muscle tremors. Several analytical methods have been developed to identify and quantify clenbuterol in different biological matrices. In this report, we have developed a specific and sensitive analytical method for quantifying clenbuterol and performed an in-depth enantiomeric analysis in bovine urine. The method was evaluated in accordance with international guidelines, and we used an isotopically labeled analog as an internal standard. The extraction efficiency for clenbuterol in bovine urine was &gt; 98%, the limit of detection was 0.05 ng/mL and the limit of quantification was 0.10 ng/mL. Our assay showed high specificity, no carryover was observed and the assay was linear in the range 0.10–8.0 ng/mL. Fifteen bovine urine samples were analyzed (containing clenbuterol), and an enantiomeric analysis was performed. The clenbuterol concentration range was 0.10–10.56 ng/mL across these samples. The levorotatory enantiomer was detected at greater concentrations than the dextrorotatory enantiomer, the ratio being 1.7 ± 0.6 (n = 15), and a statistical difference was observed (P &lt; 0.05) using the Wilcoxon test.