Parietin
| Names | |
|---|---|
| Preferred IUPAC name
1,8-Dihydroxy-3-methoxy-6-methylanthracene-9,10 dione | |
| Other names
Physcion(e), rheochrysidin, methoxyemodin
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| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.007.561 |
| KEGG | |
PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| C16H12O5 | |
| Molar mass | 284.267 g·mol−1 |
| Appearance | Orange/yellow solid |
| Hazards | |
| GHS labelling: | |
| Warning | |
| H315, H319, H335 | |
| P261, P264, P264+P265, P271, P280, P302+P352, P304+P340, P305+P351+P338, P319, P321, P332+P317, P337+P317, P362+P364, P403+P233, P405, P501 | |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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10 mg/kg (mouse, intraperitoneal) |
| Related compounds | |
Related compounds
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Emodin |
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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Parietin, or physcion, is the predominant cortical pigment of lichens in the genus Caloplaca, a secondary product of the lichen Xanthoria parietina, and a pigment found in the roots of curled dock (Rumex crispus). It has an orange-yellow color and absorbs blue light.
Parietin has also been shown to protect lichens against UV-B light, at high altitudes in alpine regions. The UV-B light stimulates production of parietin, protecting the lichens from damage. Lichens in arctic regions such as Svalbard retain this capability though they do not encounter damaging levels of UV-B, a capability that could help protect the lichens in case of ozone layer thinning.
It has also shown antifungal activity against barley powdery mildew and cucumber powdery mildew, more efficiently in the latter case than treatments with fenarimol and polyoxin B.
It reacts with KOH to form a deep, reddish-magenta compound.