HORMONAL ACTIVITY OF ECDYSTEROIDS FROM CERTAIN ASIATIC PLANTS

Ecdysone activity of ecdysteroids and ecdysteroid conjugates from plants 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 range of dosages which is characterized by 2-10 mug limits in Sarcophaga, 7-12 mug in Galleria and 17-42 mug g-1 of larval body mass in Dermestes. The largest deviation from this rule has been found with turkesterone, which contains a ''corticoid-like'' hydroxylic function at C-11. Turkesterone (11,20-dihydroxyecdysone) is 10-fold more effective than ecdysterone (20-hydroxyecdysone) in Sarcophaga and Dermestes while it is almost inactive in Galleria. The biologically most active ecdysteroid conjugates are the esters of benzoic acid. Small but definite activity has been found in certain acetonides, while ecdysteroid glucosides and polyacetylated analogues were completely inactive in all injection assays.