Isoflavones
Isoflavones
these are now known to be derived from the flavanone, not the chalcone stage.
a 2-hydroxy flavanone intermediate is involved
there are about 650 known isoflavonoids, 234 are aglycones
they are often physiologically active
they are commonly prenylated
often are phytoalexins
many biosynthetic studies done with soybeans and by adding elicitors
many isoflavones lack the 5-hydroxy group, this loss occurs before cyclization of the A ring, probably
before the chalcone stage
mainly found in the Fabaceae (Papilionoideae) (Leguminosae)
but they occur in a few other families as well.
many are antifungal, some, e.g., coumestrol, are weak estrogens
Coumestans
these compounds have a coumarin structure
Isoflavans e.g., 5-methoxysativan
Pterocarpans
about 140 known
pisatin, one of the earliest phytoalexins studied
phaseollin, medicarpin, maackiain, all important phytoalexins, mainly in legumes
some fungi can metabolize these compounds to less toxic forms (for them) ... this is an important mode of resistance
both pathogenic and non-pathogenic fungi can do this
Rotenoids
prenylation and cyclization
Amorpha, Derris, Lonchocarpus (all legumes)
these compounds inhibit oxidative phosphorylation
many have been used as piscicides and insecticides
Related Images
(-)-Maackiain and (-)-medicarpin biosynthesis
© David S. Seigler, Integrative Biology 425, Plant Secondary Metabolism, Department of Plant
Biology, 265 Morrill Hall, 505 S. Goodwin Ave., University of Illinois, Urbana, Illinois 61801, USA.
217-333-7577. seigler@life.uiuc.edu.
