Molting hormones

Figure 8.8 is an example of the use of solvent extraction to Isolate and concentrate the insect molting hormone eedysterone... 

While the above observation is interesting and could possibly have some implications for the control of the pink bollworm, the complexity of the steroid nucleus of ponasterone A and other molting hormone analogs and their weak insecticidal effect when applied topically or administered orally to most species of economically important insects may preclude their commercialization. The only commercial use of the molting hormone analogs thus far has been in the sericultural industry for the synchronization of cocoon spinning of silkworm colonies (17). 

Figure 6. Stereostructures of the Insect Molting Hormone, Ecdysterone, and a Plant Analog, Ponasterone A...

Ecdysone, a highly hydroxylated steroid (Fig. 22-12), is a molting hormone for insects.331,332 Several molecules with ecdysone activity are known, and some of these are produced by certain plants. Although ecdysones are needed by insects for larval molting, they are toxic in excess. Perhaps plants protect themselves from insects by synthesizing these substances. 

Ecdysteroids. Ecdysteroids can be isolated from many species of the annual kingdom that belong to the phyla Protomia, e.g., insects, worms, and arthropods, as well as a variety of different plant species. Ecdysteroids include the molting hormones, however, nnl all the over 60 ecdysteroids that have been isolated are active hormones. Ecdysteroids from animals... 

Dehydroxylation.1 Treatment of the photoecdysteroid muristerone (1) with ( ISi((H3)3 and Nal results in 14-desoxymuristerone (2). Unlike 14-desoxysteroids, which generally are less active than the 14a-hydroxy counterparts, 2 exhibits enhanced activity as an insect molting hormone. 

K. Nakanishi, Past and present studies with ponasterones, the first insect molting hormones from plants , Steroids, 1992, 57, 649-657. 

The area covered by natural products chemistry is boundless as it deals with nature itself. There is literally no limit to the topics to be dealt with. This volume 29 continues the tradition of supplying us with superb review articles written by experts. The articles in this volume deal with the screening, isolation, structure, synthesis, biosynthesis, and pharmacology of plant and microbial natural products that exhibit antimitotic, cancer chemotherapeutic, enzyme inhibitory, antiinflammatory, antibiotic and molting hormone activities. The compound types also cover a huge range of natural products, i.e., polyketides, terpenoids, sugars, alkaloids, proteins, and enzymes. 

Early studies reported that the crustacean molting hormone, 20-hydroxyecdysone (48), was a sex pheromone in the shore crab C. maenas and was also found in several other crab species.104 However, many authors have provided convincing evidence that this is not the case for most crab species. Despite their intriguing reproductive behavior, crustacean sex pheromones have rarely been elucidated. 

Insecticides Acting as Ecdysone Agonists, or Blocking Molting Hormone Activity... 

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