{{chembox | Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 400271366 | Name = Isorhamnetin | ImageFile = 3-methylquercetin.svg | ImageSize = 250px | ImageName = Isorhamnetin structure | ImageFile2 = Isorhamnetin.png | ImageSize2 = 250px | ImageName2 = Isorhamnetin 3D structure | IUPACName = 3,4′,5,7-Tetrahydroxy-3′-methoxyflavone | SystematicName = 3,5,7-Trihydroxy-2-(4-hydroxy-3-methoxyphenyl)-4''H''-1-benzopyran-4-one | OtherNames = 3-methylquercetin<br />3-Methylquercetin<br />Isorhamnetol<br />isorhamentin<br />isorhamnetine<br />iso-rhamnetin<br />3'-Methoxyquercetin |Section1={{Chembox Identifiers | CASNo_Ref = {{cascite|correct|CAS}} | CASNo = 480-19-3 | PubChem = 5281654 | ChEBI_Ref = {{ebicite|changed|EBI}} | ChEBI = 6052 | ChEMBL_Ref = {{ebicite|changed|EBI}} | ChEMBL = 379064 | UNII_Ref = {{fdacite|changed|FDA}} | UNII = 07X3IB4R4Z | KEGG_Ref = {{keggcite|changed|kegg}} | KEGG = C10084 | ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}} | ChemSpiderID = 4444973 | SMILES = COC1=C(C=CC(=C1)C2=C(C(=O)C3=C(C=C(C=C3O2)O)O)O)O | InChI = 1/C16H12O7/c1-22-11-4-7(2-3-9(11)18)16-15(21)14(20)13-10(19)5-8(17)6-12(13)23-16/h2-6,17-19,21H,1H3 | InChIKey = IZQSVPBOUDKVDZ-UHFFFAOYAD | StdInChI_Ref = {{stdinchicite|changed|chemspider}} | StdInChI = 1S/C16H12O7/c1-22-11-4-7(2-3-9(11)18)16-15(21)14(20)13-10(19)5-8(17)6-12(13)23-16/h2-6,17-19,21H,1H3 | StdInChIKey_Ref = {{stdinchicite|changed|chemspider}} | StdInChIKey = IZQSVPBOUDKVDZ-UHFFFAOYSA-N

}} |Section2={{Chembox Properties | Formula = C<sub>16</sub>H<sub>12</sub>O<sub>7</sub> | MolarMass = 316.26 g/mol | Density = | MeltingPtC = 307 | BoilingPt = }} }}

'''Isorhamnetin''' is an O-methylated flavon-ol from the class of flavonoids. A common food source of this 3'-methoxylated derivative of quercetin and its glucoside conjugates are pungent yellow or red onions, in which it is a minor pigment, quercetin-3,4'-diglucoside and quercetin-4'-glucoside and the aglycone quercetin being the major pigments.<ref>{{cite journal | pmid = 17997520 | doi=10.1021/jf0712503 | volume=55 | title=Onions: a source of unique dietary flavonoids | date=December 2007 | journal=J. Agric. Food Chem. | pages=10067–80 | last1 = Slimestad | first1 = R | last2 = Fossen | first2 = T | last3 = Vågen | first3 = IM| issue=25 | bibcode=2007JAFC...5510067S }}</ref> Pears, olive oil, wine and tomato sauce are rich in isorhamnetin.<ref>{{Cite journal|last1=Holland|first1=Thomas M.|last2=Agarwal|first2=Puja|last3=Wang|first3=Yamin|last4=Leurgans|first4=Sue E.|last5=Bennett|first5=David A.|last6=Booth|first6=Sarah L.|last7=Morris|first7=Martha Clare|author-link7=Martha Clare Morris|date=2020-01-29|title=Dietary flavonols and risk of Alzheimer dementia|journal=Neurology|language=en|volume=94|issue=16|pages=e1749–e1756|doi=10.1212/WNL.0000000000008981|issn=0028-3878|pmc=7282875|pmid=31996451}}</ref> Almond skin is a rich source of isorhamnetin-3-O-rutinoside and isorhamnetin-3-O-glucoside, in some cultivars they comprise 75% of the polyphenol content, the total of which can exceed 10 mg/100 gram almond.<ref>PMID 25544797 PMC4276397</ref> Others sources include the spice, herbal medicinal<ref>{{cite journal|doi=10.1021/jf053071w | volume=54 | title=Antifungal and Antibacterial Activities of Mexican Tarragon (Tagetes lucida) | journal=Journal of Agricultural and Food Chemistry | pages=3521–3527 | last1 = Céspedes | first1 = Carlos L.| year=2006 | issue=10 | pmid=19127719 | bibcode=2006JAFC...54.3521C }}</ref> and psychoactive Mexican tarragon ''(Tagetes lucida)'', which is described as accumulating isorhamnetin and its 7-O-glucoside derivate.<ref>Abdala, 1999</ref> Nopal (Opuntia ficus-indica (L.)) is also a good source of isorhamnetin, which can be extracted by supercritical fluid extraction assisted by enzymes.<ref>{{cite journal|doi=10.1016/j.supflu.2017.11.030 | volume=141 | title=Supercritical CO2 enzyme hydrolysis as a pretreatment for the release of isorhamnetin conjugates from Opuntia ficus-indica (L.) Mill | date=November 2018 | journal=The Journal of Supercritical Fluids | pages=21–28 |vauthors=Antunes-Ricardo M, Garcia-Cayuela T, Mendiola JA, Ibañez E, Gutierrez-Uribe JA, Cano MP, Guajardo-Flores D| s2cid=103893093 }}</ref>

==Biosynthesis and metabolism== The enzyme luteolin O-methyltransferase uses S-adenosyl methionine to methylate the flavanol, quercetin, giving isorhamnetin.<ref>{{cite journal |last1=Muzac |first1=Ingrid |last2=Wang |first2=Jing |last3=Anzellotti |first3=Dominique |last4=Zhang |first4=Hong |last5=Ibrahim |first5=Ragai K. |title=Functional Expression of an Arabidopsis cDNA Clone Encoding a Flavonol 3′-O-Methyltransferase and Characterization of the Gene Product |journal=Archives of Biochemistry and Biophysics |date=2000 |volume=375 |issue=2 |pages=385–388 |doi=10.1006/abbi.1999.1681 |pmid=10700397 }}</ref><ref>{{cite journal |last1=Liu |first1=Weixin |last2=Feng |first2=Yi |last3=Yu |first3=Suhang |last4=Fan |first4=Zhengqi |last5=Li |first5=Xinlei |last6=Li |first6=Jiyuan |last7=Yin |first7=Hengfu |title=The Flavonoid Biosynthesis Network in Plants |journal=International Journal of Molecular Sciences |date=2021 |volume=22 |issue=23 |article-number=12824 |doi=10.3390/ijms222312824 |doi-access=free |pmid=34884627 |pmc=8657439 }}</ref>

The enzyme 3-methylquercetin 7-O-methyltransferase further methylates isorhamnetin to produce rhamnazin.<ref name=DeLuca>{{cite journal | vauthors = De Luca V, Ibrahim RK | date = 1985 | title = Enzymatic synthesis of polymethylated flavonols in Chrysosplenium americanum. I. Partial purification and some properties of S-adenosyl-L-methionine:flavonol 3-, 6-, 7-, and 4'-O-methyltransferases | journal = Arch. Biochem. Biophys. | volume = 238 | pages = 596&ndash;605 | pmid = 3994393 | doi = 10.1016/0003-9861(85)90205-X | issue = 2 }}</ref>

Isorhamnetin is an inhibitor of CYP1B1.<ref>{{cite journal | last1= Li |first1=Fei|last2=Zhu |first2=Weifeng|last3=Gonzalez|first3= Frank J| date = October 2017 | title = Potential role of CYP1B1 in the development and treatment of metabolic diseases | journal = Pharmacology & Therapeutics | volume = 178 | pages = 18-30 | pmid = 28322972|pmc=5600638 | doi = 10.1016/j.pharmthera.2017.03.007 }}</ref>

== Glycosides == * Isorhamnetin-3-O-rutinoside-7-O-glucoside * Isorhamnetin-3-O-rutinoside-4'-O-glucoside * Narcissin (Isorhamnetin-3-O-rutinoside)

== See also == * List of antioxidants in food * List of phytochemicals in food * Tamarixetin, the 4'-methyl analog

== References == {{Reflist}}

== External links == * [http://www.chemblink.com/products/480-19-3.htm Isorhamnetin on chemblink.com]

{{flavonol}}

Category:O-methylated flavonols Category:Resorcinols Category:Tetrols Category:CYP1B1 inhibitors