Chemistry:Glaucine

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Glaucine, also known as 1,2,9,10-tetramethoxyaporphine and sold under the brand names Glauvent and Tusidil among others, is an aporphine alkaloid, antitussive (cough suppressant), and hallucinogen.[1][2][3][4][5] It is found in several different plant species in the family Papaveraceae, such as Glaucium flavum,[6] Glaucium oxylobum, and Corydalis yanhusuo,[7][8] and in other plants such as Croton lechleri in the family Euphorbiaceae.[9] Glaucine was first described following isolation from Glaucium flavum in 1839 and its chemical structure became known in 1911.[1][10][11]

Uses

Medical

Glaucine is currently used as an antitussive agent in Iceland, as well as Romania, Bulgaria, Russia and other Eastern European countries.[1][12][5] Bulgarian pharmaceutical company Sopharma sells glaucine in tablet form, where a single dose contains 40 mg. It is known to be sold over-the-counter.[1]

Recreational

Reports of recreational use of glaucine have 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, and hallucinations.[13][5] Investigation of side effects in a clinical setting also reports that the hallucinatory effects manifest as bright and colorful visualizations. They further 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".[13]

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".[5]

Side effects

Glaucine may produce side effects such as sedation, sleepiness, fatigue, weakness, nausea, pupil dilation, and hallucinogenic effects such as visual hallucinations and dissociation.[1][14][13]

Pharmacology

Pharmacodynamics

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.[12] 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.[15] In this way, glaucine can prevent smooth muscle from contracting, allowing it to relax.

It is 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.[12]

Glaucine has been found to act on the serotonin 5-HT2 receptors.[16][17] (S)-Glaucine is partial agonist of the serotonin 5-HT2A and 5-HT2C receptors, whereas (R)-glaucine is a positive allosteric modulator of the serotonin 5-HT2A receptor and possibly of the other two serotonin 5-HT2 receptors.[16][17] At the serotonin 5-HT2A receptor, (S)-glaucine showed an affinity (Ki) of 966 nM, EC50 of 661 nM, and an Emax of 42%, whereas at the serotonin 5-HT2C receptor, it displayed an EC50 of 447 nM and an Emax of 52%.[16] Activation of the serotonin 5-HT2A receptor is notably known to be responsible for the hallucinogenic effects of serotonergic psychedelics like psilocybin, LSD, and mescaline.[18][19] However, while activation of the serotonin 5-HT2A receptor may be involved, the underlying mechanism of action responsible for the hallucinogenic effects of glaucine remains unknown.[1] Glaucine also shows affinity for the serotonin 5-HT1A and 5-HT7 receptors (Ki = 171 nM and 43 nM, respectively).[17]

Both (R)-glaucine and (S)-glaucine antagonize the α1-adrenergic receptor.[16] Glaucine has been demonstrated to be a dopamine receptor antagonist, favoring dopamine D1 and D1-like receptors.[5][20] Besides actions on monoamine receptors, glaucine inhibits monoamine oxidase A (MAO-A), but its IC50 could not be determined due to solubility issues.[21]

It has bronchodilator, neuroleptic,[22] and antiinflammatory effects, acting as a PDE4 inhibitor and calcium channel blocker,[12] TLRs plays role in its anti inflammatory effects.[23] Glaucine has been reported to reduce blood pressure and heart rate and to possess anticonvulsant and antinociceptive effects in animals.[24][25]

Pharmacokinetics

The pharmacokinetics of glaucine have been studied in humans[26] and in horses.[27] In addition, the in-vitro human metabolism of glaucine has been studied.[28]

Chemistry

Stereoisomerism

Glaucine is a racemic mixture of (S)- and (R)- enantiomers.[2] (S)-Glaucine is the form that mainly occurs in nature.[2] However, while it was originally believed that only (S)-glaucine occurs in nature, (R)-glaucine has since been found in fire poppy (Papaver californicum).[29] The form used in medicine appears to exclusively be the (S) enantiomer and not the racemic mixture or (R)- enantiomer.[2][4]

Glaucine stereoisomerism

Synthesis

The chemical synthesis of glaucine has been described.[2][1]

Analogues

Analogues of glaucine include other aporphine alkaloids like apomorphine, boldine, bulbocapnine, nantenine, nuciferine, and pukateine, among many others.[10][30][31]

Certain synthetic analogues of glaucine such as 2-hydroxy-11-(2-methylallyl)oxynoraporphine are known to act as highly potent and high-efficacy serotonin 5-HT2A and 5-HT2C receptor agonists.[32][33]

History

Glaucine was first described by J. M. Probst via isolation from Glaucium flavum (yellow horned poppy) in 1839.[10][11][34] However, its chemical identity was not elucidated until later by other researchers, such as Richard Fischer in 1901 (chemical formula) and J. Gadamer (chemical structure) in 1911.[1][10][35][36][37] The drug subsequently came to be used used medically as an antitussive (cough suppressant) in some Eastern European countries.[4][38] Glaucine was reported to produce hallucinogenic effects in 1989.[14][13] Later, it was reported as a novel designer recreational drug in 2008.[1][5] The drug was found to act as a serotonin 5-HT2A receptor partial agonist and positive allosteric modulator in 2019.[16]

Society and culture

Availability

Glaucine is marketed for use as an antitussive (cough suppressant) in Bulgaria, Croatia, and Romania.[4]

Research

Asthma

When ingested orally has been found to increase airway conductance in humans, and has been investigated as a treatment for asthma.[12][39] The bronchodilator activity of glaucine is thought to be related to its phosphodiesterase PDE4 inhibition.[12][39]

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 "Psychoactive natural products: overview of recent developments". Annali dell'Istituto Superiore di Sanita 50 (1): 12–27. 2014. doi:10.4415/ANN_14_01_04. PMID 24695249. "Glaucine: The alkaloid glaucine, also known as boldine dimethyl ether or 1,2,9,10-tetramethoxyaporphine (Figure 1), is found in the yellow horned poppy (Glaucium flavum, formerly G. luteum), indigenous to the Mediterranean region, as well as in other plants, such as Croton lechleri (source of the latex “sangre de grado”) or the Chinese medicinal plant Corydalis yanhusuo. The alkaloid was isolated by Fischer in 1901, its structure determined by Gadamer in 1911. [...] Glaucine can also be synthesized either from the readily available boldine or, in racemic form, from papaverine. The therapeutic value of glaucine is similar to that of codeine or dextromethorphan [158, 159] but with lower abuse potential [160]. The plant has been used in folk medicine while glaucine itself is registered in some East European countries as an over-the-counter, non-opioid antitussive and bronchodilatory medicine. [...] Glaucine has been reported to cause weakness, sleepiness, nausea, mydriasis and visual or dissociative-hallucinations both with therapeutic and recreational use but the underlying pharmacology responsible for these central effects remains to be determined [162, 163]. Glaucine-containing tablets and herbal mixtures have appeared recently as “herbal highs” in the several European countries [162, 164, 165].". 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 The Dictionary of Drugs: Chemical Data: Chemical Data, Structures and Bibliographies. Springer. 14 November 2014. ISBN 978-1-4757-2085-3. https://books.google.com/books?id=0vXTBwAAQBAJ&pg=PA596. Retrieved 5 April 2026. 
  3. ↑ Concise Dictionary of Pharmacological Agents: Properties and Synonyms. Springer Science & Business Media. 6 December 2012. ISBN 978-94-011-4439-1. https://books.google.com/books?id=tsjrCAAAQBAJ&pg=PA132. Retrieved 5 April 2026. 
  4. ↑ 4.0 4.1 4.2 4.3 Index Nominum: International Drug Directory. CRC Press. 2004. ISBN 978-3-88763-101-7. https://books.google.com/books?id=EgeuA47Ocm4C&pg=PA566. Retrieved 5 April 2026. 
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 "Detection of the pharmaceutical agent glaucine as a recreational drug". European Journal of Clinical Pharmacology 64 (5): 553–554. May 2008. doi:10.1007/s00228-007-0451-9. PMID 18204834. 
  6. ↑ "HPLC Determination of Glaucine in Yellow Horn Poppy Grass (Glaucium flavum Crantz)". Pharmaceutical Chemistry Journal 38 (1): 441–442. August 2004. doi:10.1023/B:PHAC.0000048907.58847.c6. ISSN 0091-150X. "S-(+)-Glaucine (C21H25NO4) is the main alkaloid component in the grass of yellow horn poppy (Glaucium luteum L., syn. Glaucium flavum Crantz) of the family Papaveraceae". 
  7. ↑ "[Resource investigation and quality evaluation on wild Corydalis yanhusuo]". Zhongguo Zhong Yao Za Zhi = Zhongguo Zhongyao Zazhi = China Journal of Chinese Materia Medica 29 (5): 399–401. May 2004. PMID 15706885. 
  8. ↑ "Antifungal activity of the methanolic extract and alkaloids of Glaucium oxylobum". Fitoterapia 74 (5): 493–496. July 2003. doi:10.1016/s0367-326x(03)00113-8. PMID 12837370. 
  9. ↑ "Geographic distribution of three alkaloid chemotypes of Croton lechleri". Journal of Natural Products 65 (6): 814–819. June 2002. doi:10.1021/np000270v. PMID 12088421. Bibcode: 2002JNAtP..65..814M. 
  10. ↑ 10.0 10.1 10.2 10.3 "Chapter 30 The Aporphine Alkaloids". The Alkaloids: Chemistry and Physiology. 4. Elsevier. 1965. pp. 119–145. doi:10.1016/s1876-0813(08)60157-8. ISBN 0-12-469504-3. 
  11. ↑ 11.0 11.1 Ketcham BE (1902). Alkaloids of glaucium flavum. MINDS@UW Home (Thesis). The earliest chemical investigation of Glaucium flavum (1) was made by Probst in 1839, who mentions the following constituents: 1. an acrid alkaloid called by him Glaucine, [...]
  12. ↑ 12.0 12.1 12.2 12.3 12.4 12.5 "Bronchodilator and anti-inflammatory activities of glaucine: In vitro studies in human airway smooth muscle and polymorphonuclear leukocytes". British Journal of Pharmacology 127 (7): 1641–1651. August 1999. doi:10.1038/sj.bjp.0702702. PMID 10455321. 
  13. ↑ 13.0 13.1 13.2 13.3 "[Acute glaucine syndrome in the physician's practice: the clinical picture and potential danger]". Klinicheskaia Meditsina 84 (11): 68–70. 2006. PMID 17243616. 
  14. ↑ 14.0 14.1 "Sluchaĭ galliutsinopodovnogo deĭstviia glautsina". Klinicheskaia Meditsina 67 (9): 107–108. September 1989. PMID 2586025. 
  15. ↑ Nestler E, Hyman S & Malenka R. Molecular Neuropharmacology: A Foundation for Clinical Neuroscience (2nd ed.). China: McGraw-Hill Companies.
  16. ↑ 16.0 16.1 16.2 16.3 16.4 "In vitro functional evaluation of isolaureline, dicentrine and glaucine enantiomers at 5-HT2 and α1 receptors". Chem Biol Drug Des 93 (2): 132–138. February 2019. doi:10.1111/cbdd.13390. PMID 30216681. 
  17. ↑ 17.0 17.1 17.2 "Semisynthetic Studies on and Biological Evaluation of N-Methyllaurotetanine Analogues as Ligands for 5-HT Receptors". J Nat Prod 78 (4): 722–729. April 2015. doi:10.1021/np500893h. PMID 25695425. 
  18. ↑ "The neural basis of psychedelic action". Nat Neurosci 25 (11): 1407–1419. November 2022. doi:10.1038/s41593-022-01177-4. PMID 36280799. 
  19. ↑ "Hallucinogens". Pharmacol Ther 101 (2): 131–181. February 2004. doi:10.1016/j.pharmthera.2003.11.002. PMID 14761703. 
  20. ↑ "Structure-affinity relationships of halogenated predicentrine and glaucine derivatives at D1 and D2 dopaminergic receptors: halogenation and D1 receptor selectivity". Bioorganic & Medicinal Chemistry 13 (11): 3699–704. June 2005. doi:10.1016/j.bmc.2005.03.022. PMID 15862999. https://repositorio.uchile.cl/handle/2250/154448. 
  21. ↑ "Rapid screening and identification of monoamine oxidase-A inhibitors from Corydalis Rhizome using enzyme-immobilized magnetic beads based method". Journal of Chromatography A 1592: 1–8. May 2019. doi:10.1016/j.chroma.2019.01.062. PMID 30712820. 
  22. ↑ "Neuroleptic-like, anticonvulsant and antinociceptive effects of aporphine alkaloids: bulbocapnine, corytuberine, boldine and glaucine". Archives Internationales de Pharmacodynamie et de Therapie 296: 255–281. 1988. PMID 2907279. 
  23. ↑ "Toll-like receptor-mediated anti-inflammatory action of glaucine and oxoglaucine". Fitoterapia 80 (7): 411–4. October 2009. doi:10.1016/j.fitote.2009.05.016. PMID 19481591. https://hal-riip.archives-ouvertes.fr/pasteur-00736334/file/Fitoterapia_Ivanovska.pdf. 
  24. ↑ "Neuroleptic-like, anticonvulsant and antinociceptive effects of aporphine alkaloids: bulbocapnine, corytuberine, boldine and glaucine". Archives Internationales de Pharmacodynamie et de Therapie 296: 255–81. 1988. PMID 2907279. 
  25. ↑ "Study of the in vivo and in vitro cardiovascular effects of (+)-glaucine and N-carbethoxysecoglaucine in rats". British Journal of Pharmacology 114 (7): 1419–27. April 1995. doi:10.1111/j.1476-5381.1995.tb13364.x. PMID 7606346. 
  26. ↑ "Determination of glaucine in plasma and urine by high-performance liquid chromatography". J Chromatogr 308: 273–281. June 1984. doi:10.1016/0378-4347(84)80216-9. PMID 6746819. 
  27. ↑ "Pharmacokinetics of glaucine after intravenous and oral administrations and detection of systemic aporphine alkaloids after ingestion of tulip poplar shavings in horses". J Vet Pharmacol Ther 45 (3): 273–282. May 2022. doi:10.1111/jvp.13057. PMID 35394081. 
  28. ↑ "Studies on the in vivo contribution of human cytochrome P450s to the hepatic metabolism of glaucine, a new drug of abuse". Biochem Pharmacol 86 (10): 1497–1506. November 2013. doi:10.1016/j.bcp.2013.08.025. PMID 23988488. 
  29. ↑ "A functionally conserved STORR gene fusion in Papaver species that diverged 16.8 million years ago". Nature Communications 13 (1). June 2022. doi:10.1038/s41467-022-30856-w. PMID 35672295. Bibcode: 2022NatCo..13.3150C. 
  30. ↑ "The Aporphine Alkaloids". Chemical Reviews 64 (1): 59–79. 1 February 1964. doi:10.1021/cr60227a004. ISSN 0009-2665. 
  31. ↑ "beta-Phenylethylamines and the isoquinoline alkaloids". Natural Product Reports 5 (3): 265–292. June 1988. doi:10.1039/np9880500265. PMID 3067134. 
  32. ↑ "Discovery of New N-H Aporphine Derivatives As Brain-Penetrant Gq-Biased 5-HT2C Receptor Agonists and Dual 5-HT2C/5-HT2A Receptor Agonists". J Med Chem 68 (21): 23300–23323. November 2025. doi:10.1021/acs.jmedchem.5c02115. PMID 41108743. "Notably, the (2-methylallyl)oxy analogue 20s exhibited the highest potency at 5-HT2AR (EC50 = 6.3 nM, Emax = 82%) in this report, while displaying comparable potency at 5-HT2CR (EC50 = 8.0 nM, Emax = 95%).". 
  33. ↑ "Aporphine derivative and preparation method and application thereof". 14 June 2022. https://patents.google.com/patent/CN115108986A/en. 
  34. ↑ "Beschreibung und Darstellungsweise einiger bei der Untersuchung des Glaucium luteum aufgefundenen eigenthümlichen Stoffe, als Materialbeitrag zu einer vergleichenden Analyse der Papaveraceen". Annalen der Pharmacie 31 (3): 241–258. 1839. doi:10.1002/jlac.18390310302. ISSN 0365-5490. 
  35. ↑ "Ueber die Alkaloide von Glaucium luteum". Archiv der Pharmazie 239 (6): 426–437. 1901. doi:10.1002/ardp.19012390605. ISSN 0365-6233. 
  36. ↑ "Ueber Corydalisalkaloide (Protopin, Glaucin)". Archiv der Pharmazie 249 (3): 224–233. 1911. doi:10.1002/ardp.19112490307. ISSN 0365-6233. 
  37. ↑ "Ueber Corydalisalkaloide. (Untergruppe des Glaucins.)". Archiv der Pharmazie 249 (9): 680–701. 1911. doi:10.1002/ardp.19112490904. ISSN 0365-6233. 
  38. ↑ "Objective evaluation of dextromethorphan and glaucine as antitussive agents". British Journal of Clinical Pharmacology 17 (5): 521–524. May 1984. doi:10.1111/j.1365-2125.1984.tb02384.x. PMID 6375709. 
  39. ↑ 39.0 39.1 "Effects of inhaled glaucine on pulmonary responses to antigen in sensitized guinea pigs". Eur J Pharmacol 397 (1): 187–195. May 2000. doi:10.1016/s0014-2999(00)00224-7. PMID 10844113. 



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