ʟ-Tyrosine as a Precursor of Flavonoids in Buckwheat Cotyledons

Procyanidin Production byFagopyrum esculentumCallus Culture

“…These data show that light stimulates formation of procyanidins but it was not a limiting factor for their production. The independent effect of light on procyanidins formation was also demonstrated in vivo in Fagopyrum es- culenturn Moench seedlings (13,14). In cell cultures of Catharanthus roseus, some secondary metabolites were preferentially accumulated in light and others in darkness (15).…”

The biosynthesis of shikimate metabolites

“…NADH was a less satisfactory cofactor. A comparable activity has been isolated from cell suspension cultures of Cryptomeria japonica catalysing NADPH-dependent reduction of (+)-dihydroquercetin and ( + )-dihydrokaempferol to the corresponding 3,4-cis-flavan-3,4-diols.l14 The enzyme from flowers of Dahlia variabilis transformed ( + )-dihydrokaempferol and ( + )-dihydroquercetin into leucoanthocyanidins, though ( + )-dihydromyricetin was only slowly converted into leucodelphinidin (99).l15 In addition, the flavanones (29-naringenin and (2s)eriodictyol (103) were reduced at position 4 giving the corresponding flavan-4-01s apioforol(lO4) and luteoforol(1 OS), but flavones and flavonols were not substrates.…”

The biosynthesis of shikimate metabolites

“…The biosynthesis of tannins has been covered in a recent review.103 samples of the 2,3-trans-3,4-trans-leucoanthocyanidins leucopelargonidin (92) and leucocyanidin (93) were fed to the flowers of genetically defined lines of Matthiola incana that were blocked in the pathway of production of anthocyanidins. Almost certainly, the compounds that were fed were epimerized at C-4 to the corresponding 2,3-trans.3,4-cis-isomers ( 90) and (91) during the experiments, and the latter compounds are the actual biosynthetic intermediates (see below, and Section 5.5.). Biosynthesis of the anthocyanins pelargonidin 3-0-glucoside (95) and cyanidin 3-0-glucoside (96) was observed when (92) and (93) were used to supplement acyanic flowers of a line that was blocked at chalcone synthase; the same compounds were formed in one of two different lines that were blocked between dihydroflavonols and anthocyanins.…”