Pheromone inhibitors

Once the host cell acquires the pheromone-responsive plasmid, it apparently shuts off the production of the corresponding pheromone. It has been revealed that two systems are involved in this phenotypic change. One is the production of pheromone inhibitor, each pheromone-responsive plasmid encodes a pheromone inhibitor, termed iX , which is an antagonist peptide of sex pheromone. The other one is shutdown of pheromone production, which is accomplished by a plasmid-encoded protein (TraB for pADl and pPDl and PrgY for pCFlO).107-110... 

Mori, K. Stereoselective synthesis of ( )-e Jo-brevicomin, a pheromone inhibitor produced by Dendroctonus bark beetles. Agric. Biol. Chem. 40, 2499—2500 (1976). 

Some observed side-products (87 or 90) can be suppressed, for example by the use of modified catalysts (Pd(dba)2/4—6equiv. PPh3 instead of Pd(PPh3)4 in Eq. 14.10). Additional model studies demonstrated the utility of a-allenyl acetates and phosphates by the successful synthesis of pheromone (R)-94 [47] and of enzyme inhibitor 95 [48] (Scheme 14.20). 

Esterases of the Juvenile Hormone of Insects Many works have been dedicated to the inhibition of esterases of the juvenile hormone of insects. The purpose of these works is to control insect populations by ehminating their metamorphosis. Among the numerous trifluoromethyl ketones that have been synthesized, thioalkyl derivatives of trifluoroacetone have been shown to be the most active ones. Curiously, the corresponding alcohols are also excellent inhibitors. Trifluoromethyl ketones can also inhibit other insect esterases antenna esterases and esterases that are involved in the release of pheromones (Figure 7.33). The inhibition of these latter ones can also be interesting for insect control purposes. 

Inhibitor of Sesamia nonagrioides sexual pheromone esterase... 

A trail pheromone of the Pharaoh ant was identified as 3-butyl-5-methylindolizidine of the stereochemistry given in (219) (75JHC289). Slaframine (220) is a metabolite isolated from Rhizoctonia leguminicola responsible for producing excessive salivation in cattle. A stereoselective synthesis was reported (73JOC3848). Swainsonine (221), a potent inhibitor of a-mannosidase, has been isolated from Swainsona caneszens. The stereochemistry was derived from the NMR spectrum (79AJC2257). 

Pheromone Disruption and Inhibitors. Pheromones play an important role in the landing and attack behavior of bark beetles (9, 11, 12). Attractants orient flying beetles to a common host tree in high numbers over a relatively short time period. Two techniques have been recently developed to take advantage of the southern pine beetle response to pheromones. 

Byers J. A. (1983) Bark beetle conversion of a plant compound to a sex-specific inhibitor of pheromone attraction. Science 220, 624—626. 

In this chapter we will review the current state of knowledge about how pheromone production is regulated in female moths. Discussion of PBAN identification and localization within the nervous system will be followed by how PBAN acts to stimulate pheromone biosynthesis. The final major topic will be a discussion of mediators and inhibitors of PBAN action. A considerable amount of information has accumulated with regard to regulation of pheromone biosynthesis in moths since Pheromone Biochemistry (Prestwich and Blomquist, 1987) was first published, and this chapter is not all inclusive. Further information can also be obtained in several reviews (Raina, 1993 Jurenka, 1996 Teal et al., 1996 Rafaeli et al., 1997b Raina, 1997 Rafaeli, 2002). 

Hirashima A., Eiraku T., Watanabe Y., Kuwano E., Taniguchi E. and Eto M. (2001) Identification of novel inhibitors of calling and in vitro [C-14]acetate incorporation by pheromone glands of Plodia interpunctella. Pest Manag. Sci. 57, 713-720. 

Hunt D. W. A. and Smirle M. J. (1988) Partial inhibition of pheromone production in Dendroctonus ponderosae (Coleoptera Scolytidae) by polysubstrate monooxygenase inhibitors. J. Chem. Ecol. 14, 529-536. 

An antennal-specific aldehyde oxidase (AOX) of M. sexta (MsexAOX) was the next identified pheromone-degrading enzyme (Rybczynski el al., 1989). The activity of MsexAOX was visualized on non-denaturing PAGE, and was shown to be antennal specific but present in sensilla of both male and female antennae. MsexAOX was observed as a dimer with a combined estimated molecular mass of 295 kDa. M. sexta uses a multicomponent pheromone consisting exclusively of aldehydes including bombykal (Starratt el al., 1979 Tumlinson el al., 1989, 1994) MsexAOX was shown to degrade bombykal to its carboxylic acid. Both TLC and spectrophotometric assays were established and a variety of substrates and inhibitors were characterized. Making adjustments for the concentrations and volumes within a sensillum lumen, the in vivo half-life of pheromone was estimated at 0.6 msec in the presence of this enzyme (Rybczynski el al., 1989). 

Pophof B. (1998) Inhibitors of sensillar esterase reversibly block the responses of moth pheromone receptor cells. J. Comp. Physiol. A 183, 153-164. 

Renou M., Berthier A., Desbarats L., Van der Pers J. and Guerrero A. (1999) Actographic analysis of the effects of an esterase inhibitor on male moth responses to sex pheromone. Chem. Senses 24, 423 128. 

Riba M., Sans A., Bau P., Grolleau G., Renou M. and Guerrero A. (2001) Pheromone response inhibitors of the com stalk borer Sesamia nonagrioides. Biological evaluation and toxicology. J. Chem. Ecol. 27, 1879-1897. 

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