Isorhamnetin is an
O-methylated flavon-ol from the class of
flavonoid
Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans.
Chemically, flavonoids ...
s. 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. Pears, olive oil, wine and tomato sauce are rich in isorhamnetin. 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. Others sources include the spice, herbal medicinal and
psychoactive Mexican tarragon ''(
Tagetes lucida)'', which is described as accumulating isorhamnetin and its 7-O-glucoside derivate. Nopal (Opuntia ficus-indica (L.)) is also a good source of isorhamnetin, which can be extracted by
supercritical fluid extraction assisted by enzymes.
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
References
External links
Isorhamnetin on chemblink.com
{{flavonol
O-methylated flavonols
Resorcinols
Tetrols