Triterpenes and Steroids in Invertebrates

7 Triterpenes and Steroids in Invertebrates Insects.—Terpenoid metabolism in insects will be considered separately from other invertebrates. Although insects do not possess the complete machinery required for biosynthesis of sterols from small molecules, it has been reported that a Sarcophaga bullata homogenate converts squalene into a compound with the chromatographic properties of squalene 2,3-oxide. However, this report warrants substantiation. The major insect juvenile hormone (133 R = Me) becomes labelled from [ C]acetate and also from l-[ H or 

Ikekawa, M. Morisaki, H. Ohtaka, and Y. Chiyoda, Chem. Comm.. 1971, 1498. 

Further metabolism of ecdysones in insects can occur by conversion into both less and more polar metabolites as well as into glycoside and sulphate conjugates. ° Ecdysone (143) is metabolized by a soluble enzyme from blowfly pupae into 2p,14o,22,25-tetrahydroxy-5p-cholest-7-ene-3,6-dione(145 3-dehydroecdysone). A non-specific enzyme system from larval gut tissues 

Hikioo, Y. Ohizumi, T. Saito, E Nakamura, and T. Takemoto, Chem. and Pham. Bull. (Japan), 1972.20,851. 

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