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:||Biosynthesis → Secondary Metabolites Biosynthesis → Phenylpropanoid Derivatives Biosynthesis → Flavonoids Biosynthesis|
Expected Taxonomic Range: Viridiplantae
phlorizin is a phenylproponoid derivative also known as phloretin 2-beta glucoside, it is a dihydrochalcone and the structure closely resembles the precursors chalcones [Gosch10]. phlorizin was first discovered in 1835 as a bitter tasting compound in barks of apple trees. Its distribution in the plant kingdom seems more widely present in the Malus species. Tissue distribution of the compound differs considerably; in Malus pumila and Lithocarpus polystachyus it mainly exists in fruits, in Malus hupehensis it is found in the stem and root barks, young leaves and fruits. The root bark contained more of it than the stem bark [Wang10b]. In Malus domestica, 90% of the soluble phenolics in the leaves is that of the dihydrochalcone phlorizin.
This compound has been used for medicinal properties for a long time, modern medicine uses it in the control of blood sugar levels, protective agent to the heart from scavenging oxygen free radicals and antioxidant injuries. Studies have also shown that phlorizin has estrogenic and antiestrogenic activities [Wang10b]. Dihydrochalcones are related to flavonoids but very less is known about their biosynthetic route, some enzymes have been cloned and it seems to depend on the presence of a dehydrogenase that can convert the substrate 4-dihydrocoumaroyl-CoA from 4-coumaryl-CoA. No phlorizin biosynthesis occurs in Pyrus communis which is a closely related species of apples. This is due to the absence of the enzyme capable of catalyzing the first step of the biosynthesis namely the formation of 4-dihydrocoumaroyl-CoA from 4-coumaryl-CoA [Gosch09].
Gosch09: Gosch, Christian, Halbwirth, Heidi, Kuhn, Jasmin, Miosic, Silvija, Stich, Karl "Biosynthesis of phloridzin in apple (Malus domestica Borkh.) [electronic resource]." Plant science. [Ireland]: Elsevier Science Ireland Ltd. 2009 Feb., v. 176, no. 2 p. 223-231. AGRICOLA: IND44141307
Jugde08: Jugde H, Nguy D, Moller I, Cooney JM, Atkinson RG (2008). "Isolation and characterization of a novel glycosyltransferase that converts phloretin to phlorizin, a potent antioxidant in apple." FEBS J 275(15);3804-14. PMID: 18573104
Rubio06: Rubio S, Larson TR, Gonzalez-Guzman M, Alejandro S, Graham IA, Serrano R, Rodriguez PL (2006). "An Arabidopsis mutant impaired in coenzyme A biosynthesis is sugar dependent for seedling establishment." Plant Physiol 140(3);830-43. PMID: 16415216
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