C-Glucosylflavonoid biosynthesis from 2-hydroxynaringenin by Desmodium uncinatum (Jacq.) (Fabaceae)

[2′,3′,5′,6′-2H4]-2-Hydroxynaringenin is synthesised and incubated with commercially available UDP-glucose and the crude protein extract from Desmoduim uncinatum leaves. The organic extract produces isotopically labelled [2′,3′,5′,6′-2H4]-vitexin and [2′,3′,5′,6′-2H4]-isovitexin. Repeating the experiment with denatured protein or replacing the 2-hydroxynaringenin with [2′,3′,5′,6′-2H4]-apigenin or [2′,3′,5′,6′-2H4]-naringenin results in no observable incorporation. 2-Hydroxynaringenin is therefore the substrate for C-glucosylflavonoid biosynthesis in D. uncinatum.

2-Hydroxynaringenin is C-glucosylated by UDP-glucose and a protein extract from Desmodium uncinatum leaves to afford vitexin and isovitexin. This is the first committed step to C-glucosylflavonoids, a biologically active class of natural compounds.