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MetaCyc Pathway: ponciretin biosynthesis
Inferred from experimentTraceable author statement to experimental support

Pathway diagram: ponciretin biosynthesis

This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.

Superclasses: BiosynthesisSecondary Metabolites BiosynthesisPhenylpropanoid Derivatives BiosynthesisFlavonoids BiosynthesisFlavanones Biosynthesis

Some taxa known to possess this pathway include : Glycine max

Expected Taxonomic Range: Fabales

General Background

Ponciretin, the 4'-O-methyl derivate of naringenin occurs in plants where its antifungal activity may be involved in the defense against pathogenic attacks. The modification of compounds via O-methylation occurs frequently in nature and is thought to increase their lipophilicity being associated with potentially higher antimicrobial activities [Middleton94]. In contrast to the likewise frequent glycosylation that also modifies compounds O-methylation appears to be far more specific in plants [Ibrahim98].

Besides antimicrobial properties, ponciretin has also been reported to possess anti-allergenic capacities [Park05b] and efficiently inhibits growth and activity of the gastritis and peptic ulcer disease causing bacteria Helicobacter pylori in humans [Bae99] [Kim99b].

About This Pathway

The enzyme has been characterized in vitro to be regiospecific for naringenin to form ponciretin. However, other substrates such as the isoflavones daidzein and genistein as well as quercetin (dihydroflavone) and apigenin (flavone) were also converted to their 4'-O-methyl derivatives with varying but rather high turnover rates. The fact that ponciretin has not been found in soybean indicates that more likely daidzein represents the in vivo substrate in this plant [Kim05a].

In contrast to that the enzyme involved in the 4'-O-methylation of daidzein to form formononetin ( formononetin biosynthesis) and genistein to produce biochanin-A ( isoflavonoid biosynthesis II) does not accept naringenin [Wengenmayer74] [He00] indicating that the enzymes involved are different. Another 4'-O-methyltransferase purified from Glycyrrhiza echinata involved in the formation of formonoetin is even more specific and does not convert daidzein or flavanone but only 2,7,4'-trihydroxyisoflavanone [Akashi03]. Yet another 4'-O-methyltransferase isolated recently from Catharanthus roseus very specifically methylated homoeriodictyol (3'-O-methyl-eriodictyol) in vitro and was discussed with regard to the substrate substitution pattern preferred for the subsequent enzymes involved in the flavonoid biosynthetic route [Schroder04].

The 4'-O-methyltransferase forming ponciretin (this pathway) seems to be very similar to the one involved in the biosynthesis of acacetin, the 4'-O-methyl derivate of apigenin ( acacetin biosynthesis). However, this enzyme expresses a pronounced specificity towards apigenin and converted naringenin with only half the efficiency compared to apigenin [Kuroki81]. The current lack of relevant data requires the further investigation of those enzymes to determine their in vivo relationship across different species.

Created 21-Feb-2006 by Foerster H, TAIR


Akashi03: Akashi T, Sawada Y, Shimada N, Sakurai N, Aoki T, Ayabe S (2003). "cDNA cloning and biochemical characterization of S-adenosyl-L-methionine: 2,7,4'-trihydroxyisoflavanone 4'-O-methyltransferase, a critical enzyme of the legume isoflavonoid phytoalexin pathway." Plant Cell Physiol 44(2);103-12. PMID: 12610212

Bae99: Bae EA, Han MJ, Kim DH (1999). "In vitro anti-Helicobacter pylori activity of some flavonoids and their metabolites." Planta Med 65(5);442-3. PMID: 10454900

He00: He XZ, Dixon RA (2000). "Genetic manipulation of isoflavone 7-O-methyltransferase enhances biosynthesis of 4'-O-methylated isoflavonoid phytoalexins and disease resistance in alfalfa." Plant Cell 12(9);1689-702. PMID: 11006341

Ibrahim98: Ibrahim RK, Bruneau A, Bantignies B (1998). "Plant O-methyltransferases: molecular analysis, common signature and classification." Plant Mol Biol 36(1);1-10. PMID: 9484457

Kim05a: Kim DH, Kim BG, Lee Y, Ryu JY, Lim Y, Hur HG, Ahn JH (2005). "Regiospecific methylation of naringenin to ponciretin by soybean O-methyltransferase expressed in Escherichia coli." J Biotechnol 119(2);155-62. PMID: 15961179

Kim99b: Kim DH, Bae EA, Han MJ (1999). "Anti-Helicobacter pylori activity of the metabolites of poncirin from Poncirus trifoliata by human intestinal bacteria." Biol Pharm Bull 22(4);422-4. PMID: 10328566

Kuroki81: Kuroki G, Poulton JE (1981). "The para-O-methylation of apigenin to acacetin by cell-free extracts of Robinia pseudoacacia L." Z. Naturforsch. 36c, 916-920.

Middleton94: Middleton Jr E, Kandaswami C (1994). "The impact of plant flavonoids on mammalian biology: implications for immunity, inflammation and cancer." In: Harborne JB (ed.). The Flavonoids: Advances in Research since 1986. Chapman & Hall, London, 619-652.

Park05b: Park SH, Park EK, Kim DH (2005). "Passive cutaneous anaphylaxis-inhibitory activity of flavanones from Citrus unshiu and Poncirus trifoliata." Planta Med 71(1);24-7. PMID: 15678369

Schroder04: Schroder G, Wehinger E, Lukacin R, Wellmann F, Seefelder W, Schwab W, Schroder J (2004). "Flavonoid methylation: a novel 4'-O-methyltransferase from Catharanthus roseus, and evidence that partially methylated flavanones are substrates of four different flavonoid dioxygenases." Phytochemistry 65(8);1085-94. PMID: 15110688

Wengenmayer74: Wengenmayer H, Ebel J, Grisebach H (1974). "Purification and properties of a S-adenosylmethionine: isoflavone 4'-O-methyltransferase from cell suspension cultures of Cicer arietinum L." Eur J Biochem 50(1);135-43. PMID: 4452353

Other References Related to Enzymes, Genes, Subpathways, and Substrates of this Pathway

Latendresse13: Latendresse M. (2013). "Computing Gibbs Free Energy of Compounds and Reactions in MetaCyc."

Wang99c: Wang J, Pichersky E (1999). "Identification of specific residues involved in substrate discrimination in two plant O-methyltransferases." Arch Biochem Biophys 368(1);172-80. PMID: 10415125

Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by Pathway Tools version 19.5 (software by SRI International) on Fri Apr 29, 2016, biocyc11.