Apigenin

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Apigenin[1]
Apigenin
Names
IUPAC name
4′,5,7-Trihydroxyflavone
Systematic IUPAC name
5,7-Dihydroxy-2-(4-hydroxyphenyl)-4H-1-benzopyran-4-one
Other names
Apigenine; Chamomile; Apigenol; Spigenin; Versulin; C.I. Natural Yellow 1
Identifiers
3D model (
JSmol
)
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard
 100.007.540 Edit this at Wikidata
IUPHAR/BPS
KEGG
UNII
  • InChI=1S/C15H10O5/c16-9-3-1-8(2-4-9)13-7-12(19)15-11(18)5-10(17)6-14(15)20-13/h1-7,16-18H checkY
    Key: KZNIFHPLKGYRTM-UHFFFAOYSA-N checkY
  • InChI=1/C15H10O5/c16-9-3-1-8(2-4-9)13-7-12(19)15-11(18)5-10(17)6-14(15)20-13/h1-7,16-18H
    Key: KZNIFHPLKGYRTM-UHFFFAOYAX
  • O=C\1c3c(O/C(=C/1)c2ccc(O)cc2)cc(O)cc3O
Properties
C15H10O5
Molar mass 270.240 g·mol−1
Appearance Yellow crystalline solid
Melting point 345 to 350 °C (653 to 662 °F; 618 to 623 K)
UV-vis (λmax) 267, 296sh, 336 nm in methanol[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Apigenin (4′,5,7-trihydroxyflavone), found in many plants, is a

glycosides
. It is a yellow crystalline solid that has been used to dye wool.

Sources in nature

Apigenin is found in many fruits and vegetables, but parsley, celery, celeriac, and chamomile tea are the most common sources.[3] Apigenin is particularly abundant in the flowers of chamomile plants, constituting 68% of total flavonoids.[4] Dried parsley can contain about 45 mg apigenin/gram of the herb, and dried chamomile flower about 3–5 mg/gram.[5] The apigenin content of fresh parsley is reportedly 215.5 mg/100 grams, which is much higher than the next highest food source, green celery hearts providing 19.1 mg/100 grams.[6]

Pharmacology

Apigenin competitively binds to the benzodiazepine site on GABAA receptors.[7] There exist conflicting findings regarding how apigenin interacts with this site.[8][9]

Biosynthesis

Apigenin is biosynthetically derived from the general phenylpropanoid pathway and the flavone synthesis pathway.[10] The phenylpropanoid pathway starts from the aromatic amino acids L-phenylalanine or L-tyrosine, both products of the Shikimate pathway.[11] When starting from L-phenylalanine, first the amino acid is non-oxidatively deaminated by phenylalanine ammonia lyase (PAL) to make cinnamate, followed by oxidation at the para position by cinnamate 4-hydroxylase (C4H) to produce p-coumarate. As L-tyrosine is already oxidized at the para position, it skips this oxidation and is simply deaminated by tyrosine ammonia lyase (TAL) to arrive at p-coumarate.[12] To complete the general phenylpropanoid pathway, 4-coumarate CoA ligase (4CL) substitutes coenzyme A (CoA) at the carboxy group of p-coumarate. Entering the flavone synthesis pathway, the type III polyketide synthase enzyme chalcone synthase (CHS) uses consecutive condensations of three equivalents of malonyl CoA followed by aromatization to convert p-coumaroyl-CoA to chalcone.[13] Chalcone isomerase (CHI) then isomerizes the product to close the pyrone ring to make naringenin. Finally, a flavanone synthase (FNS) enzyme oxidizes naringenin to apigenin.[14] Two types of FNS have previously been described; FNS I, a soluble enzyme that uses 2-oxogluturate, Fe2+, and ascorbate as cofactors and FNS II, a membrane bound, NADPH dependent cytochrome p450 monooxygenase.[15]

Glycosides

The naturally occurring glycosides formed by the combination of apigenin with sugars include:

In diet

Some foods contain relatively high amounts of apigenin:[17]

Product Apigenin
(milligrams per 100 grams)
Chamomile 300-500
Parsley 215.5
Celery hearts, green 19.1
Rutabagas, raw 4

See also

References

  1. ^ Merck Index, 11th Edition, 763.
  2. ^ The Systematic Identification of Flavonoids. Mabry et al, 1970, page 81
  3. ^ The compound in the Mediterranean diet that makes cancer cells 'mortal' Emily Caldwell, Medical Express, May 20, 2013.
  4. PMID 26487830
    .
  5. PMID 29399439
    .
  6. ^ Delage, PhD, Barbara (November 2015). "Flavonoids". Corvallis, Oregon: Linus Pauling Institute, Oregon State University. Retrieved 2021-01-26.
  7. PMID 7617761
    .
  8. PMID 10543878
    .
  9. PMID 10751547
    .
  10. ISSN 0179-9541
    .
  11. PMID 7870841
    .
  12. PMID 25975614
    .
  13. PMID 12636085
    .
  14. PMID 11524111
    .
  15. PMID 16332809
    .
  16. S2CID 8223136
    .
  17. ^ USDA Database for the Flavonoid Content of Selected Foods, Release 3 (2011)
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