Quantitation of psilocin in human plasma by high-performance liquid chromatography and electrochemical detection: comparison of liquid–liquid extraction with automated on-line solid-phase extraction

Two modifications of the HPLC–ED method with respect to extraction procedure used have been developed for psilocin, the active metabolite of psilocybin, in human plasma using either liquid–liquid extraction (LLE) or automated on-line solid-phase extraction (on-line SPE). Each type of the sample preparation required a different HPLC system followed by electrochemical detection at 650 to 675 mV. The limit of quantitation of both modifications was 10 ng/ml psilocin. There was no significant difference observable between the LLE and the on-line SPE in terms of method standard deviation (LLE 1.82%, on-line SPE 1.13%) and the analytical results. However, the advantages of on-line SPE in addition to different selectivity were less manual effort, smaller plasma volumes of 400 μl (LLE 2 ml) and a recovery of psilocin in human plasma of nearly 100% (LLE 88%). In contrast to a previous procedure both methods were rapid, simple and reliable and yielded high plasma recoveries. They were used successfully in the quantitation of psilocin in plasma samples obtained from healthy volunteers after p.o. administration of 0.2 mg psilocybin per kg body mass. Plasma concentration curves and pharmacokinetic parameters were calculated.     

The molecular basis of the antidepressant action of the magic mushroom extract,psilocin

Magic mushrooms, and their extract psilocybin, are well-known for their psychedelic properties and recreational use. Psilocin, the bio-active form of psilocybin, can potentially treat various psychiatric diseases. Psilocin putatively exerts its psychedelic effect as an agonist to the serotonin 2A receptor (5-HT_2AR), which is also the receptor for the neurological hormone serotonin. The two key chemical differences between the two molecules are first, that the primary amine in serotonin is replaced with a tertiary amine in psilocin, and second, the hydroxyl group is substituted differently on the aromatic ring. Here, we find that psilocin can bind to 5-HT_2AR with an affinity higher than serotonin, and provide the molecular logic behind the higher binding affinity of psilocin using extensive molecular dynamics simulations and free energy calculations. The binding free energy of psilocin is dependent upon the protonation states of the ligands, as well as that of the key residue in the binding site: Aspartate 155. We find that the tertiary amine of psilocin, and not the altered substitution of the hydroxyl group in the ring is responsible for the increased affinity of psilocin. We propose design rules for effective antidepressants based on molecular insights from our simulations.