Defensive steroids from a carrion beetle (Silpha americana).
The defensive anal effluent discharged by Silpha americana in response to disturbance contains a mixture of steroids stemming from a glandular annex of the rectum. The compounds have been characterized as 15 beta-hydroxyprogesterone (1, principal component), 5 beta-pregnan-15 beta-ol-3,20-dione (2), 5 beta-pregnan-3 alpha, 15 beta-diol-20-one (3), 5 beta-pregnan-7 beta, 15 beta-diol-3,20-dione (4), 5 beta-pregnan-3 alpha, 7 beta, 15 beta-triol-20-one (5), 5 beta-pregnan-16 alpha-ol-3,20-dione (6), and 5 beta-pregnan-3 alpha, 16 alpha-diol-20-one (7), none previously found in insects. Bioassays with jumping spiders showed compounds 1 and 6 to be feeding deterrents at the 1 microgram level.
D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D002845:Chromatography; D001517:Coleoptera / Q000502:physiology*; D004435:Eating / Q000187:drug effects; D005088:Exocrine Glands / Q000032:analysis; D006908:Hydroxyprogesterones / Q000302:isolation & purification / Q000494:pharmacology; D011276:Pregnanediol / Q000031:analogs & derivatives; D011277:Pregnanediones / Q000302:isolation & purification; D011278:Pregnanes / Q000302:isolation & purification* / Q000494:pharmacology; D011279:Pregnanetriol / Q000031:analogs & derivatives; D012007:Rectum; D013057:Spectrum Analysis; D013112:Spiders / Q000502:physiology
D006908:Hydroxyprogesterones; D011277:Pregnanediones; D011278:Pregnanes; D011279:Pregnanetriol; C044666:15-hydroxyprogesterone; D011276:Pregnanediol