Insect hormones in vertebrates: anabolic effects of 20-hydroxyecdysone in Japanese quail.

Ecdysteroids are hormones controlling cell proliferation, growth and the developmental cycles of insects and other invertebrates. They are occasionally present in various unrelated plants for no apparent reason; no phytohormonal function has yet been identified. In certain cases, ecdysteroids are accumulated to high levels in leaves, roots or seeds. Some ecdysteroid-containing plants have been known as medicinal plants for centuries. One of them, Leuzea carthamoides Iljin (Asteraceae), growing in Central Asia, contains 0.4% ecdysteroid in dry roots and 2% in seeds. A pharmacological preparation from this plant, "Ecdisten', is already available as a commercial preparation for its anabolic, tonic and other effects, for medical use (review). It remained problematic, however, whether ecdysteroids were truly responsible for these effects, because Leuzea contains a number of other biologically active compounds in addition to ecdysteroids. We extracted and purified ecdysteroids from the seeds of Leuzea. With 6 g of 96% 20-hydroxyecdysone (20E), we made a large-scale feeding assay with Japanese quail to find out whether ecdysteroid alone could duplicate the anabolic effects of the seeds. We found that the 96% ecdysteroid increased the mass of the developing quails in a dose-dependent manner, with the rate of increase proportional to the ecdysteroid content in the seeds; there was a 115% increase in living mass with 100 mg kg-1 of pure 20E compared with 109.5% increase with 100-180 mg kg-1 20E equivalents in the seeds. We conclude that the plethora of growth-promoting, vitamin-like effects induced in vertebrates by Leuzea is mediated by ecdysteroids.