Morgenstern und Ubendstern

Mirasorvone: A masked 20-ketopregnane from the defensive secretion of a diving beetle ( Thermonectus marmoratus )

“…A high-temperature hydrogenolysis experiment performed with mirasorvone, which gave the same pattern of hydrocarbon products (GC-MS analysis) as that of an authentic sample of progesterone (8), established the presence of a pregnane skeleton (15,16). Because all natural pregnanes are oxygenated (or aminated) at C-3 and C-20, we assumed that mirasorvone must also be oxygenated at these sites.…”

“…Pregnanes are also ejected by diving beetles (Dytiscidae) (6) and a species of water bug (Belostomatidae) (7). The steroids, in the case of these aquatic insects, have been shown to be distasteful and toxic to both fish and amphibians (6,(8)(9)(10)(11). We have studied the defensive chemistry of Thermonectus marmoratus, an aposematic dytiscid beetle recently named the ''sunburst diving beetle'' (12) (Fig.…”

Chemical defense: Aquatic beetle ( Dineutes hornii ) vs. fish ( Micropterus salmoides )

“…They possess defensive glands from which they eject noxious fluids when disturbed, fluids containing compounds that have in some cases been characterized. Diving beetles (Dytiscidae) (1), for instance, and belostomatid bugs (Belostomatidae) (2) produce steroids, primarily pregnanes (C21-steroids), shown to have strong defensive potential against fish (1,(3)(4)(5). § Also investigated has been the defensive chemistry of the so-called whirligig beetles (Gyrinidae).…”