DISTRIBUTION AND IDENTITIES OF PHYTOECDYSTEROIDS IN THE GENUS BRIZA (GRAMINEAE)

Within the genus Briza, phytoecdysteroids are predominantly associated with native Eurasian species, while none of the native South American species tested was found to accumulate detectable levels of ecdystero ids in their seeds. Bioassay/RIA-guided HPLC analysis led to the isola tion of six known ecdysteroids (abutasterone, ecdysone, 20-hydroxyecdy sone, polypodine B, pterosterone and sidisterone) from the seeds of Br iza maxima. The structures of these compounds were elucidated by UV, E IMS and a series of 1D and 2D NMR experiments, notably H-1 NMR, C-13 P ENDANT, COSY 45, HMBC, HMQC and NOESY. The distributions of ecdysteroi ds present in different plant parts of Briza spp. were analysed by RIA . Those species containing detectable levels of ecdysteroids in the se eds (B. elatior, B. maxima, B. media and B. minima) possessed even hig her levels of ecdysteroids in the plants, while the other species, wit h undetectable ecdysteroid levels in the seeds, possessed very low (pr obably biologically insignificant) levels in the plants. The highest l evels of ecdysteroids are associated with meristematic region at the r oot/aerial interface in plants of B. elatior. (C) 1998 Elsevier Scienc e Ltd. All rights reserved.