Biosynthesis of Flavanon

Flavanones, a direct precursor to the most flavonoids, synthesized from the amino acid phenylalanine or tyrosine. The process begins with the enzyme phenylalanine / tyrosine ammonia lyase (PAL / TAL), change buillding block of amino acids into phenyl-propanoic acid. Biosynthetic pathway involving the enzyme flavanones, cytochrome-P450, cinnamate 4-hydroxylase (C4H), by adding 4'-hydroxyl group of the aromatic ring of phenylalanine. The next CoA esters synthesized from phenylpropanoic acids with the help of enzymes phenylpropanoyl-CoA ligases, such as 4 - coumaryl: CoA ligase (4CL). Type III polyketide synthase Chalcone synthase (CHS) then catalyzes the sequential condensation of three malonyl-CoA CoA-ester with 1 form chalcones. This is the step that produces flavonoid biosynthesi.

 First, there is an alternative pathway enzymes type III polyketide synthases that have high homology with CHS (> 70%) using the same precursor form stilbenes (using 3 units of malonyl-CoA), benzylacetolactone (only use 1 unit malonyl-CoA), and other aromatic molecules.

Flavanones final structure is formed only if diisomerisasi chalcones into (2S)-flavanone by Chalcone isomerase (CHI), this reaction occurs spontaneously at alkaline conditions. Once formed flavanones, a lot of compound enzymes could alter the functional group or alter the conformation of the 3-ring core fenilpropan produces up to 8000 different compounds structure.Functionalization can be hydroxylation, reduction, alkylation, oxidation, and glukosilasi, each alone or in combination. By nature, these enzymes exist in plants, but according to reports Ueda et al. that there is a type III polyketide synthases derived from microorganisms. This information is essential for the production of compounds flavanones in scale bioreactor.

The addition of consecutive carbon atoms of malonyl-CoA by CHS are shown in green, red, and blue. R group showed hydroxylation patterns on natural flavonoid unnatural although substitutions can occur in this position. Abbreviations: DFR dihydroflavanone reductase, reductase leucoanthocynanidin LAR, ANS anthocyanidin synthase, 3GT uridine, flavanone 3-glucoside transferase, FSI flanone synthase, CHR Chalcone reductase, IFS isoflavanone synthase, flavanone hydroxytransferase FHT, FLS flavonol synthase.