This was one of two molecules for this week.
May 13, 2019
Our future as anxiety drugs hasn’t panned out.
What molecules are we?
Image of Harman 3D Image of Harman
Image of Harman 3D Image of Harman

Chrysin (on the left) and harman (right) are organic compounds with distinctly different structures, but both are found in the passionflower species Passiflora caerulea and P. incarnata.

Chrysin, also called 5,7-dihydroxyflavone, was first isolated from the wood of pine trees (Pinus spp.) in 1949 by Gösta Linstedt at the KTH Royal Institute of Technology (Stockholm). Harman (or harmane), a pyridoindole derivative, was discovered much earlier (1861) in the bark of P. incarnata and other trees by German researcher R. Rieth.

What do chrysin and harman have in common besides occurrence in trees, specifically P. incarnata? More than 500 passionflower species have been used as traditional folk remedies for anxiety and other medical conditions almost everywhere that they grow on Earth. For at least 20 years, drug researchers have sought to elucidate mechanisms by which passionflower biochemicals provide relief.

In a key 2001 study, P. incarnata extract was compared with oxazepam, an early benzodiazepine anxiolytic drug, for efficacy against generalized anxiety disorder (GAD). Shaheen Akhondzadeh and colleagues at the Tehran University of Medical Sciences and the Institute of Medicinal Plants (both in Tehran, Iran) treated 36 patients diagnosed with GAD with P. incarnata extract, oxazepam, or placebo in a 4-week trial.

The extract and the drug gave equally positive results. Oxazepam acted more rapidly, but it also impaired the subjects’ job performance whereas the extract did not. In the time since this report was issued, however, there is no record of US Food and Drug Administration filings for chrysin, harman, or passionflower extracts.

This discussion of anxiety remedies reminds us that today is the beginning of Mental Health Awareness Week.

Chrysin and harman hazard information

GHS classification* for both: not a hazardous substance or mixture

*Globally Harmonized System of Classification and Labeling of Chemicals. 

Chrysin fast facts

CAS Reg. No.480-40-0
Empirical formulaC15H10O4
Molar mass254.24 g/mol
AppearanceYellow or beige crystals or powder
Melting point285.5 ºC
Water solubilitySparingly soluble

Harman fast facts

CAS Reg. No.486-84-0
Empirical formulaC12H10N2
Molar mass182.23 g/mol
AppearanceWhite, light beige, or light yellow crystals or powder
Melting point236.5 ºC
Water solubilityInsoluble
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Learn more about this molecule from CAS, the most authoritative and comprehensive source for chemical information.

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