HORMONAL ACTIVITY OF ECDYSTEROIDS FROM CERTAIN ASIATIC PLANTS

Ecdysone activity of ecdysteroids and ecdysteroid conjugates from plan ts has been determined in three species of insects, Sarcophaga bullata (Diptera), Galleria mellonella (Lepidoptera) and Dermestes vulpinus ( Coleoptera). Standardized injection assays were made on the ligatured last instar larvae, the hormonal activity was expressed in the common ED-50 units. The activity of most ecdysteroids falls within a narrow r ange of dosages which is characterized by 2-10 mug limits in Sarcophag a, 7-12 mug in Galleria and 17-42 mug g-1 of larval body mass in Derme stes. The largest deviation from this rule has been found with turkest erone, which contains a ''corticoid-like'' hydroxylic function at C-11 . Turkesterone (11,20-dihydroxyecdysone) is 10-fold more effective tha n ecdysterone (20-hydroxyecdysone) in Sarcophaga and Dermestes while i t is almost inactive in Galleria. The biologically most active ecdyste roid conjugates are the esters of benzoic acid. Small but definite act ivity has been found in certain acetonides, while ecdysteroid glucosid es and polyacetylated analogues were completely inactive in all inject ion assays.