P. Dewick
1977
Citations
0
Influential Citations
75
Citations
Quality indicators
Journal
Phytochemistry
Abstract
Abstract Feeding experiments have demonstrated that 7,2′-dihydroxy-4′-methoxy-isoflavone-[ 14 C-Me] and -isoflavanone-[ 14 C-Me] are extremely efficient precursors of the phytoalexin demethylhomopterocarpin in Cu 2+ -treated red clover seedlings. Neither of these compounds, nor demethylhomopterocarpin-[ 14 C-Me], was incorporated into a second pterocarpan phytoalexin, maackiain. 3-Hydroxy-9-methoxypterocarp-6a-ene-[ 14 C-Me] was a poor precursor of both pterocarpans. A biosynthetic pathway to demethylhomopterocarpin via 2′-hydroxylation of formononetin (7-hydroxy-4′-methoxyisoflavone) and subsequent reduction to the isoflavanone is proposed. The conversion of this isoflavanone into the pterocarpan may involve the corresponding isoflavanol and a carbonium ion intermediate. The branch-point to maackiain is probably at the formononetin stage. The presence of two coumestans, 9- O -methylcoumestrol and medicagol, previously unreported in red clover, is demonstrated. Biosynthetic implications are discussed.