Phosphate conjugation, insects

While formation of phosphate conjugates Is well-known for Insects (75,76), this pathway Is documented rarely for other animals. Ngah and Smith (66) have shown that eight Insect species In five different orders can produce phosphates from 4-nltrophenol. The mealworm, Tenebrlo, also phosphorylates 8-qulnollnol, 1-naphthol, and 4-methylumbelllferone. The few known examples of phosphates from xenobiotics In mammals have been reviewed (2) and Include phenol (cat, sheep), 2-naphthylamlne (dog, human), and ethanol (rat). 2-Naphthylamlne Is converted Into an unusual conjugate, bis(2-amlno-l-naphthyl)phosphate. 

Photographic reducer and developer reagent for the determination of small quantities of phosphate, dye intermediate stabilizer in paints and varnishes motor fuels and oils antioxidant for fats and oils, and a polymerization inhibitor. Therapeutically used topically for depigmentation to treat skin blemishes, for example, hypermelanosis. Hydroquinone occurs naturally, as a conjugate with jS-o-glucopyranoside, in the leaves, bark, and fruit of a number of plants, and its presence may be an important factor in fire-blight resistance in the pear. It may also play an important part in the defense mechanisms of some insects. 

While the biosynthesis of phosphate esters is common in intermediary metabolism, the conjugation of foreign compounds with phosphate is encountered only rarely in vertebrate species (3,7,28). Indeed, to date, insects appear to be the only major group of organisms that utilize this pathway to any significant extent in the metabolism of foreign compounds (3,6,7). 

As has been discussed in relation to sulfate conjugation, there is increasing evidence that phosphate formation may play a critical role in regulating insect steroids this is particularly true for steroids present in eggs and during early stages of embryonic development. 

---