FLUCTUATION OF PHYTOECDYSTEROIDS IN DEVELOPING SHOOTS OF TAXUS-CUSPIDATA

Phytoecdysteroids from the vegetative shoots of Taxus cuspidate, an evergreen shrub, were found to fluctuate at different developmental stages during shoot growth. The quantity of ecdysterone (2β,3β,14α,20R,22R,25-hexahydroxy-5β-cholest-7-en-6-one) was 47±5 mg/kg fresh weight, while the quantity of ponasterone A (2β,3β,14α,20R,22R-pentahydroxy-5β-cholest-7-en-6-one) was 23 mg/kg from leaves of one- to two-year-(52-104 week) old shoots. One-, four-, 18- and 37-week-old leaves and soft shoots contained, on a fresh weight basis, respectively, 56, 52, 114 and 127 mg/kg of ecdysterone and 2, 2, 23 and 15 mg/kg of ponasterone A. These results indicate that ecdysteroid accumulation is dynamic and possibly driven by cycles of synthesis, transport, and degradation. © 1990.