20-Hydroxyecdysone insects

Hydroxyecdysone insects, Crustacea Widespread in plants Serratula ECDY-R agonist (8nM)... 

It has been demonstrated that 1,2-diacyl-l-alkylhydrazines represent a new class of selective insecticides in which RH-5849 and its structurally related analogs proved to be the first nonsteroidal mimics of 20-hydroxyecdysone insect molting hormone. Hopefully, by using this and other new insect growth regulators, we can gradually reduce our dependence on the conventional insecticides which have given us many problems related to the environmental impact. 

Caterpillars and other moulting insects excrete the hormone a-ecdysone which at moulting time becomes hydroxylated to 20-hydroxyecdysone (20-E), which in turn triggers the moulting process enabling the insect to shed its exoskeleton and resume feeding. Rohm and Hass have developed a novel insecticide, tebufenozide (Formula 9.5) which mimics 20-E, binding to the same site. The consequence of this is that the insect stops... 

Fukamizo, T. and Kramer, K.J. (1987) Effect of 20-hydroxyecdysone on chitinase and P-Af-acetylglucosaminidase during the larval-pupal transformation on Manduca sexta (L.). Insect Biochemistry 17, 547-550. 

Abstract Pheromones are utilized by many insects in a complex chemical communication system. This review will look at the biosynthesis of sex and aggregation pheromones in the model insects, moths, flies, cockroaches, and beetles. The biosynthetic pathways involve altered pathways of normal metabolism of fatty acids and isoprenoids. Endocrine regulation of the biosynthetic pathways will also be reviewed for the model insects. A neuropeptide named pheromone biosynthesis activating neuropeptide regulates sex pheromone biosynthesis in moths. Juvenile hormone regulates pheromone production in the beetles and cockroaches, while 20-hydroxyecdysone regulates pheromone production in the flies. 

The three hormones that regulate pheromone production in insects are shown in Figure 1.1. PBAN alters enzyme activity through second messengers at one or more steps during or subsequent to fatty acid synthesis during pheromone production (Rafaeli and Jurenka, Chapter 5). In contrast, 20-hydroxyecdysone and JH induce or repress the synthesis of specific enzymes at the transcription level (Tittiger, Chapter 7 Blomquist, Chapter 9). 

Figure 1.1 The three major types of hormones that regulate pheromone production in insects. A Juvenile Hormone III (C16 JH), B 20-Hydroxyecdysone and C PBANs from the corn earworm, Helicoverpa zea (Raina et al., 1989), the silkworm moth Bombyx mori (Kitamura et al., 1989) and the gypsy moth, Lymantira dispar (Master et al., 1994). The minimum sequence (pentapeptide) required for activity is indicated.

Adams T. S., Dillwith J. W. and Blomquist, G. J. (1984b) The role of 20-hydroxyecdysone in housefly sex pheromone biosynthesis. J. Insect Physiol. 30, 287-294. 

The three hormones that regulate pheromone production in insects are juvenile hormone 111 (JH), 20-hydroxyecdysone and PBAN (pheromone biosynthesis activating neuropeptide). 

The plant-insect chemical interactions concerning the stilbenoids have just been reviewed [509] (-i-)-Ampelopsin B (806) and ct-viniferin (635) antagonized the action of 20-hydroxyecdysone [510] cw-miyabenol A (735), kobophenol B and cw-miyabenol C (663) showed competitive binding to ecdysteroid receptors [337] resveratrol (1) and oligomers (suffruticosols A-C, 589-591) also exhibited ecdysteroid antagonistic activity [297]. 

The ability of insect sulfotransferases to catalyze the sulfation of plant and insect steroids may simply reflect the broad substrate specificity of the enzymes. On the other hand, it may be indicative of a more important physiological function of the enzymes. Sulfate esters of cholesterol, campesterol and e-sitosterol have been identified in the meconium of tobacco hornworm (M. sexta) pupae ( ), and these steroids are known precursors of a-and e-ecdysone and other molting hormones in this species ( ). Further, there is evidence that houseflies (M. domestica) and diapausing pupae of M. sexta convert 22,25 bisdeoxyecdysone, a-ecdysone and 20-hydroxyecdysone into sulfate and glucoside conjugates ( ). 

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