P. Dewick, Maria Martin
1979
Citations
1
Influential Citations
52
Citations
Journal
Phytochemistry
Abstract
Abstract Feeding experiments have shown that 2′-7-dihydroxy-4′-methoxy-isoflavone-[Me- 14 C] and -isoflavanone-[Me- 14 C] are efficient precursors of the phytoalexins demethylhomopterocarpin, sativan and vesitol in CuCl 2 -treated lucerne ( Medicago sativa ) seedlings. Demethylhomopterocarpin-[Me- 14 C] was also incorporated into sativan and vestitol, and vestitol-[Me- 14 C] was incorporated into demethylhomopterocarpin and sativan. Thus, the pterocarpan demethylhomopterocarpin and the 2′-hydroxy-isoflavan vestitol are interconvertible in M. sativa , but incorporation data, and the results of kinetic feeding experiments with l -phenylalanine-[U- 14 C] suggest that these compounds are synthesized simultaneously from a common intermediate, which could be involved in the interconversion. A carbonium ion, derived from an isoflavanol, a likely intermediate in the biosynthetic reductive sequence from 2′,7-dihydroxy-4′-methoxy-isoflavone and -isoflavanone, is proposed as this common intermediate. 7-Hydroxy-2′,4′-dimethoxyisoflavone-[4′-Me- 14 C] was a very poor precursor of all three phytoalexins. Sativan, then, is most probably derived by methylation of vestitol. The incorporation of vestitol-[Me- 14 C] into demethylhomopterocarpin, but not into maackiain, pterocarpan phytoalexins of red clover ( Trifolium pratense ), is also demonstrated.