Grayanic acid
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| IUPAC name
1-Heptyl-3-hydroxy-9-methoxy-7-methyl-6-oxobenzo[b][1,4]benzodioxepine-2-carboxylic acid
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| Other names
Grayanic acid
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| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
PubChem CID
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| Properties | |
| C23H26O7 | |
| Molar mass | 414.454 g·mol−1 |
| Appearance | colourless needles |
| Melting point | 186–189 °C (367–372 °F; 459–462 K) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
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Grayanic acid is an organic compound found in certain lichens, particularly Cladonia grayi, where it serves as a secondary metabolite with notable taxonomic importance. Identified in the 1930s, it is now recognised as a chemotaxonomic marker that helps distinguish closely related species within the Cladonia chlorophaea species group. Grayanic acid crystallises as colourless, needle-like structures, melts at approximately 186–189 °C (367–372 °F), and displays distinctive fluorescence under ultraviolet light, aiding in its detection and study.
Chemically, grayanic acid is a depsidone, featuring two aromatic rings linked by ester and ether bonds. Its biosynthesis occurs in the fungal partner of the lichen and does not require the presence of the algal symbiont. Genetic research has identified a key biosynthetic gene cluster responsible for its formation, highlighting biochemical pathways and enzymes that convert precursor compounds into grayanic acid and related metabolites such as sphaerophorin.
Beyond its chemical characteristics, grayanic acid has proven invaluable in refining lichen taxonomy, as variations in its presence and concentration underpin subtle species distinctions. By comparing grayanic acid profiles across different populations and geographic regions, researchers have gained insights into evolutionary relationships, species distribution patterns, and the ecological roles that these fungal–algal partnerships play in diverse environments.