Steroid metabolism in Bombyx mori, I. Catabolism of ponasterone A and ecdysterone in Bombyx mori.

Ponasterone A, when injected into silkworm larvae (Bombyx mori), was hydroxylated at C-25 and C-26 with the formation of ecdysterone and inokosterone, followed by fission at C-20:C-22 to form poststerone. The catabolism of ecdysterone to poststerone was also clarified. These conversions are thought to constitute part of the detoxication mechanism for exogenous ecdysones in the insect.