Isorhamnetin

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.^[1] Pears, olive oil, wine and tomato sauce are rich in isorhamnetin.^[2] 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.^[3] Others sources include the spice, herbal medicinal^[4] and psychoactive Mexican tarragon (Tagetes lucida), which is described as accumulating isorhamnetin and its 7-O-glucoside derivate.^[5] Nopal (Opuntia ficus-indica (L.)) is also a good source of isorhamnetin, which can be extracted by supercritical fluid extraction assisted by enzymes.^[6]

Isorhamnetin

Isorhamnetin structure
Isorhamnetin 3D structure
Names
IUPAC name 3,4′,5,7-Tetrahydroxy-3′-methoxyflavone
Systematic IUPAC name 3,5,7-Trihydroxy-2-(4-hydroxy-3-methoxyphenyl)-4H-1-benzopyran-4-one
Other names 3-methylquercetin 3-Methylquercetin Isorhamnetol isorhamentin isorhamnetine iso-rhamnetin 3'-Methoxyquercetin
Identifiers
CAS Number	480-19-3 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:6052 N
ChEMBL	ChEMBL379064 N
ChemSpider	4444973 N
ECHA InfoCard	100.006.860
KEGG	C10084 N
PubChem CID	5281654
UNII	07X3IB4R4Z N
CompTox Dashboard (EPA)	DTXSID10197379
InChI InChI=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 N Key: IZQSVPBOUDKVDZ-UHFFFAOYSA-N N 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 Key: IZQSVPBOUDKVDZ-UHFFFAOYAD
SMILES COC1=C(C=CC(=C1)C2=C(C(=O)C3=C(C=C(C=C3O2)O)O)O)O
Properties
Chemical formula	C16H12O7
Molar mass	316.26 g/mol
Melting point	307 °C (585 °F; 580 K)
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

Metabolism

The enzyme quercetin 3-O-methyltransferase uses S-adenosyl methionine and quercetin to produce S-adenosylhomocysteine and isorhamnetin.

The enzyme 3-methylquercetin 7-O-methyltransferase uses S-adenosyl methionine and 5,7,3',4'-tetrahydroxy-3-methoxyflavone (isorhamnetin) to produce S-adenosylhomocysteine and 5,3',4'-trihydroxy-3,7-dimethoxyflavone (rhamnazin).

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