Parietin

Parietin

Names
Preferred IUPAC name 1,8-Dihydroxy-3-methoxy-6-methylanthracene-9,10 dione
Other names Physcion(e), rheochrysidin, methoxyemodin
Identifiers
CAS Number	521-61-9  Y
3D model (JSmol)	Interactive image
ChemSpider	10193  N
ECHA InfoCard	100.007.561
KEGG	C17045  N
PubChem CID	10639
UNII	H6PT94IV61  Y
CompTox Dashboard (EPA)	DTXSID20200101
InChI InChI=1S/C16H12O5/c1-7-3-9-13(11(17)4-7)16(20)14-10(15(9)19)5-8(21-2)6-12(14)18/h3-6,17-18H,1-2H3 N Key: FFWOKTFYGVYKIR-UHFFFAOYSA-N N InChI=1/C16H12O5/c1-7-3-9-13(11(17)4-7)16(20)14-10(15(9)19)5-8(21-2)6-12(14)18/h3-6,17-18H,1-2H3 Key: FFWOKTFYGVYKIR-UHFFFAOYAX
SMILES Oc1cc(OC)cc(C2=O)c1C(=O)c3c2cc(C)cc3O
Properties
Chemical formula	C16H12O5
Molar mass	284.267 g·mol−1
Appearance	Orange/yellow solid
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319, H335
Precautionary statements	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)	10 mg/kg (mouse, intraperitoneal) [1]
Related compounds
Related compounds	Emodin
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N  verify  (what is  YN ?) Infobox references

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. ^{[2] [3] [4]}

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. ^[5]

It reacts with KOH to form a deep, reddish-magenta compound.^{[ citation needed ]}

Effect on human cancer cells

Also found in rhubarb, ^[6] the orange compound appears to have potential to suppress 6-phosphogluconate dehydrogenase, or 6PGD. 6PGD is the third enzyme of the pentose phosphate pathway, or PPP, an oxidative process fueling growth in a still-relatively-unknown way. But it appears that arresting the chemical machinery at its third step could be promising for oncology.^{[ according to whom? ]} The parietin, identified from an FDA database of 2,000 known suppressors of 6PGD, killed half the human leukemia cells over two days in the laboratory. The pigment also slowed the growth of other human cancer cells in mouse models, according to the study. A more-potent derivative of the parietin called S3 may even cut the growth of lung cancer cells implanted in mice by two-thirds, over the course of 11 days. The compound also appears to be non-toxic to healthy cells. ^{[7] [8]}

References

1. Bachmann, M.; Luethy, J.; Schlatter, C. (1979-11-01). "Toxicity and mutagenicity of molds of the Aspergillus glaucus group. Identification of physcion and three related anthraquinones as main toxic constituents from Aspergillus chevalieri" . Journal of Agricultural and Food Chemistry. 27 (6): 1342–1347. Bibcode:1979JAFC...27.1342B. doi:10.1021/jf60226a021. ISSN   0021-8561. PMID   397244.
2. Gauslaa Yngvar, Margrete Ustvedt Elin (2003). "Is parietin a UV-B or a blue-light screening pigment in the lichen Xanthoria parietina?". Photochem. Photobiol. Sci. 2 (4): 424–432. Bibcode:2003PhPhS...2..424G. doi: 10.1039/b212532c . PMID   12760542.
3. Nybakken Line; Asbjørn Solhaug Knut; Bilger Wolfgang; Gauslaa Yngvar (2004). "The lichens Xanthoria elegans and Cetraria islandica maintain a high protection against UV-B radiation in Arctic habitats". Oecologia. 140 (2): 211–216. Bibcode:2004Oecol.140..211N. doi:10.1007/s00442-004-1583-6. PMID   15138881. S2CID   22917119.
4. Asbjorn Solhaug Knut (2003). "UV-induction of sun-screening pigments in lichens". New Phytologist. 158 (1): 91–100. Bibcode:2003NewPh.158...91S. doi: 10.1046/j.1469-8137.2003.00708.x .
5. Gyung Ja Choi; Seon-Woo Lee; Kyoung Soo Jang; Jin-Seog Kim; Kwang Yun Cho; Jin-Cheol Kim (December 2004). "Effects of chrysophanol, parietin, and nepodin of Rumex crispus on barley and cucumber powdery mildews". Crop Protection. 23 (12): 1215–1221. Bibcode:2004CrPro..23.1215C. doi:10.1016/j.cropro.2004.05.005.
6. "Cancer Growth Could be Slowed by Little-known Pigment in Rhubarb". Laboratory Equipment. 2015-10-22. Retrieved 2015-10-24.
7. "Orange lichens are source for potential anticancer drug". news.emory.edu. 2015-10-21. Retrieved 2015-10-24.
8. Basile, Adriana; Rigano, Daniela; Loppi, Stefano; Di Santi, Annalisa; Nebbioso, Angela; Sorbo, Sergio; Conte, Barbara; Paoli, Luca; De Ruberto, Francesca (2015-04-09). "Antiproliferative, Antibacterial and Antifungal Activity of the Lichen Xanthoria parietina and Its Secondary Metabolite Parietin". International Journal of Molecular Sciences. 16 (4): 7861–7875. doi: 10.3390/ijms16047861 . ISSN   1422-0067. PMC   4425054 . PMID   25860944.

Further reading

• Caloplaca coralloides chemistry
• Edwards, Howell G. M.; Emma M. Newton; David D. Wynn-Williams; Steven R. Coombes (2003-03-12). "Molecular spectroscopic studies of lichen substances 1: parietin and emodin". Journal of Molecular Structure. 648 (1–2): 49–59. Bibcode:2003JMoSt.648...49E. doi:10.1016/S0022-2860(02)00384-8.
• Solhaug, Knut A.; Yngvar Gauslaa (November 1996). "Parietin, a photoprotective secondary product of the lichen Xanthoria parietina". Oecologia. 108 (3): 412–418. Bibcode:1996Oecol.108..412S. doi:10.1007/BF00333715. PMID   28307855. S2CID   34925113.