Abstract
A chitin‐synthesizing cockroach cell line (UMBGE‐4) previously shown to secrete ecdysteroids was analyzed for its ability to metabolize potential precursors of ecdysone (e.g., 2‐deoxyecdysone, 2,22‐dideoxyecdysone, 2,22,25‐trideoxyecdysone, and cholesterol). All, except cholesterol, were actively metabolized by UMBGE‐4 cells. However, all but 2‐deoxyecdysone were converted to polar and hydrolyzable metabolites, and not to ecdysone. Labeling with cholesterol was unsuccessful. Labeling experiments with molting hormones, i.e., ecdysone and 20‐hydroxyecdysone, confirmed that this cell line can metabolize ecdysteroids and allowed identification of some of the products. Molting hormones were converted into acetate conjugates and polar conjugates which were often double‐conjugates, i.e., polar conjugates of acetate conjugates. Labeling experiments with ecdysone demonstrated that this cell line possesses a low ecdysone 20‐hydroxylase activity. The capacity of UMBGE‐2 cells, which do not synthesize chitin or ecdysteroids, was also examined. Neither ecdysone nor 20‐hydroxyecdysone was significantly metabolized by UMBGE‐2 cells. 2‐Deoxyecdysone and 2,22‐dideoxyecdysone were very slowly metabolized respectively to more polar compounds.