Apigenin

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Apigenin[1]
Apigenin
Apigenin-3D-balls.png
Names
IUPAC name
5,7-Dihydroxy-2-(4-hydroxyphenyl)-4H-1-benzopyran-4-one
Other names
Apigenine; Chamomile; Apigenol; Spigenin; Versulin; 4′,5,7-Trihydroxyflavone; C.I. Natural Yellow 1
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.007.540
KEGG
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-vismax) 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).
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Infobox references

Apigenin (4′,5,7-trihydroxyflavone), found in many plants, is a natural product belonging to the flavone class that is the aglycone of several naturally occurring glycosides. It is a yellow crystalline solid that has been used to dye wool.

Sources in nature[edit]

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]

Biosynthesis[edit]

Biosynthesis of Apigenin.gif

Apigenin is biosynthetically derived from the general phenylpropanoid pathway and the flavone synthesis pathway.[5] The phenylpropanoid pathway starts from the aromatic amino acids L-phenylalanine or L-tyrosine, both products of the Shikimate pathway.[6] 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.[7] 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.[8] 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.[9] 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.[10]

Glycosides[edit]

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

See also[edit]

References[edit]

  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. ^ Venigalla M, Gyengesi E, Münch G (August 2015). "Curcumin and Apigenin - novel and promising therapeutics against chronic neuroinflammation in Alzheimer's disease". Neural Regeneration Research. 10 (8): 1181–5. doi:10.4103/1673-5374.162686. PMC 4590215. PMID 26487830.
  5. ^ Forkmann, G. (January 1991). "Flavonoids as Flower Pigments: The Formation of the Natural Spectrum and its Extension by Genetic Engineering". Plant Breeding. 106 (1): 1–26. doi:10.1111/j.1439-0523.1991.tb00474.x. ISSN 0179-9541.
  6. ^ Herrmann KM (January 1995). "The shikimate pathway as an entry to aromatic secondary metabolism". Plant Physiology. 107 (1): 7–12. doi:10.1104/pp.107.1.7. PMC 161158. PMID 7870841.
  7. ^ Lee H, Kim BG, Kim M, Ahn JH (September 2015). "Biosynthesis of Two Flavones, Apigenin and Genkwanin, in Escherichia coli". Journal of Microbiology and Biotechnology. 25 (9): 1442–8. doi:10.4014/jmb.1503.03011. PMID 25975614.
  8. ^ Austin MB, Noel JP (February 2003). "The chalcone synthase superfamily of type III polyketide synthases". Natural Product Reports. 20 (1): 79–110. CiteSeerX 10.1.1.131.8158. doi:10.1039/b100917f. PMID 12636085.
  9. ^ Martens S, Forkmann G, Matern U, Lukacin R (September 2001). "Cloning of parsley flavone synthase I". Phytochemistry. 58 (1): 43–6. doi:10.1016/S0031-9422(01)00191-1. PMID 11524111.
  10. ^ Leonard E, Yan Y, Lim KH, Koffas MA (December 2005). "Investigation of two distinct flavone synthases for plant-specific flavone biosynthesis in Saccharomyces cerevisiae". Applied and Environmental Microbiology. 71 (12): 8241–8. doi:10.1128/AEM.71.12.8241-8248.2005. PMC 1317445. PMID 16332809.
  11. ^ Meyer H, Bolarinwa A, Wolfram G, Linseisen J (2006). "Bioavailability of apigenin from apiin-rich parsley in humans". Annals of Nutrition & Metabolism. 50 (3): 167–72. doi:10.1159/000090736. PMID 16407641.