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 ecdysteroids in their seeds. Bioassay/RIA-guided HPLC analysis led to the isolation of six known ecdysteroids (abutasterone, ecdysone, 20-hydroxyecdysone, polypodine B, pterosterone and sidisterone) from the seeds of Briza maxima. The structures of these compounds were elucidated by UV, EIMS and a series of 1D and 2D NMR experiments, notably H-1 NMR, C-13 PENDANT, COSY 45, HMBC, HMQC and NOESY. The distributions of ecdysteroids present in different plant parts of Briza spp. were analysed by RIA. Those species containing detectable levels of ecdysteroids in the seeds (B. elatior, B. maxima, B. media and B. minima) possessed even higher levels of ecdysteroids in the plants, while the other species, with undetectable ecdysteroid levels in the seeds, possessed very low (probably biologically insignificant) levels in the plants. The highest levels of ecdysteroids are associated with meristematic region at the root/aerial interface in plants of B. elatior. (C) 1998 Elsevier Science Ltd. All rights reserved.