Isoprenoid Compounds of Animal Origin

A number of compounds important to animal physiology have been identified as isoprenoid compounds. Notable examples are vitamin A, retinal and squalene (Table 30-1). Also, terpene hydrocarbons and oxygenated terpenes have been isolated from insects and, like farnesol, show hormonal and pheromonal activity. As one example, the juvenile hormone isolated from Cecropia silk moths has the structure shown in 3:

The structure was established by an impressive combination of chemical, spectroscopic, and synthetic methods with about 200μg of pure compound isolated from the abdomens of a myriad of male moths.

Juvenile hormone plays a critical role in maintaining the juvenile or larval stage of insects, and if its secretion is not controlled, normal development to the adult stage is prevented. Use of hormones or substances with hormonelike activity to control insect populations is an area of intense research interest and activity.  The secretion of juvenile hormone is controlled by other hormones originating in the brain (brain hormone) and the phthoracic gland (molting hormone, ecdysone; see Table 30-2).