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ECHA InfoCard | 100.006.820 |
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Formula | C21H25NO4 |
Molar mass | 355.434 g·mol−1 |
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Glaucine is an aporphine alkaloid found in several different plant species in the family Papaveraceae such as Glaucium flavum,[1] Glaucium oxylobum and Corydalis yanhusuo,[2][3] and in other plants like Croton lechleri in the family Euphorbiaceae.[4]
It has bronchodilator, neuroleptic[5] and antiinflammatory effects, acting as a PDE4 inhibitor and calcium channel blocker,[6] and is used medically as an antitussive in some countries.[7] TLRs plays role in its anti inflammatory effects.[8] Glaucine may produce side effects such as sedation, fatigue, and a hallucinogenic effect characterised by colourful visual images,[9][10] and has been detected as a novel psychoactive drug.[11] In a 2019 publication,[12] the isomer (R)-glaucine is reported to be a positive allosteric modulator of the 5-HT2A receptor, which is also associated with the hallucinogenic effects of substances such as psilocybin and mescaline.
It was believed that only the (S)-form of glaucine occurs in nature until (R)-glaucine was found in fire poppy (Papaver californicum).[13]
Glaucine (2 stereoisomers) | |
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Glaucine binds to the benzothiazepine site on L-type Ca2+-channels, thereby blocking calcium ion channels in smooth muscle like the human bronchus. Glaucine has no effect on intracellular calcium stores, but rather, does not allow the entry of Ca2+ after intracellular stores have been depleted.[6] Ca2+ influx is a vital component in the process of muscular contraction, and the blocking of this influx therefore reduces the ability of the muscle to contract.[14] In this way, glaucine can prevent smooth muscle from contracting, allowing it to relax.
Glaucine has also been demonstrated to be a dopamine receptor antagonist, favoring D1 and D1-like receptors.[11][15] It is also a non-competitive selective inhibitor of PDE4 in human bronchial tissue and granulocytes. PDE4 is an isoenzyme that hydrolyzes cyclic AMP to regulate human bronchial tone (along with PDE3). Yet as a PDE4 inhibitor, glaucine possesses very low potency.[6]
Glaucine has also recently[12] been found to have an effect on the neuronal 5-HT2A receptors, which are responsible for the hallucinogenic effects of classical psychedelics. It also inhibits MAO enzymes.[16] Its enantiomers effect are same for adrenergic receptor yet different for 5-HT receptor. Both (R)-Glaucine and (S)-Glaucine antagonizes α1 receptor but (S)-Glaucine is partial agonist of 5-HT2 subtypes whereas (R)-Glaucine is positive allosteric modulator of 5-HT2.[17]
It is currently used as an antitussive agent in Iceland, as well as Romania, Bulgaria, Russia and other eastern European countries.[6][11] Bulgarian pharmaceutical company Sopharma sells glaucine in tablet form, where a single dose contains 40 mg and the half-life is indicated to be 6–8 hours. When ingested orally has been shown to increase airway conductance in humans, and has been investigated as a treatment for asthma.[6]
Animal studies demonstrate the ability of glaucine to decrease heart rate and lower blood pressure,[18] presumably by the same mechanism of Ca2+-channel antagonism that it uses to relax bronchial muscle. Studies of the effect of several alkaloids in mice, including glaucine, demonstrate anticonvulsant and antinociceptive properties.[19] In other words; animal studies indicate that glaucine can also act as a pain reliever to a certain extent, although its capacities in this respect appear limited when compared to other analgesics.
Reports of recreational use of glaucine have recently been published, and effects include dissociative-type symptoms; feeling detached and 'in another world', as well as nausea, vomiting and dilated pupils. These reports mirror those about the effects of clinical use, which state dissociative-type symptoms as well as lethargy, fatigue, hallucinations.[10][11] Investigation of side effects in a clinical setting also reports that the hallucinatory effects manifest as bright and colorful visualizations. They also report that patients perceive their environments clearly yet feel detached from it; "the patient sees and understands everything and is oriented well enough, but cannot take a clear and adequate action".[10]
One particular report of recreational use gone awry described the form of distribution as tablets being marketed as a 1-benzylpiperazine (BZP)-free "herbal high" which the patient referred to as "head candy".[11]