Application of chiral gas chromatography with electroantennographic detection to the determination of the stereochemistry of a cockroach sex pheromone.

Abstract

The coupling of an electroantennographic detector to a chiral capillary gas chromatographic system provides a highly sensitive technique for the determination of pheromone stereochemistry. Electronic modification of the usual electroantennographic detector enables the detector to respond to the relatively broad peaks produced by chiral gas chromatographic systems. By using this methodology, supellapyrone, a female sex pheromone of the brownbanded cockroach Supella longipalpa (Orthoptera: Blattellidae), is shown to be 5-(2'R,4'R-dimethylheptanyl)-3-methyl-2H-pyran-2-one.Stereochemical discrimination may be considered the ultimate refinement of chemical communication in nature. Its importance, with respect to E-and Z-isomerism, was recognized with the characterization of bombykol more than three decades ago (1), and the significance of RIS discrimination was established several years thereafter (2).Despite the sophistication of contemporary analytical techniques, elucidation of the stereochemistry of a naturally occurring semiochemical remains one of the most difficult tasks in pheromone research (3). Most often, the stereochemistry of pheromones is not in fact analytically determined but is inferred from comparative bioassays conducted with all possible synthetic stereoisomers. This approach is unambiguous when one of the isomers is an antagonist to the natural pheromone. An example of this is provided by the Japanese beetle Popillia japonica whose sex pheromone has been identified as 5-(Z)-(-)-(dec-1-enyl)oxacyclopentan-2-one, the stereochemistry of which could be assigned as R because trap catches were reduced dramatically by the addition of the S-enantiomer (4). However, for a pheromone whose stereoisomers show similar bioactivity, the bioassay gives no information on the stereochemistry of the natural product. As an example, the final clue to the absolute configuration of the German cockroach contact sex pheromone was a classical mixture melting point determination, since all four possible stereoisomers proved to be equally bioactive (5).Recently, a sex pheromone of the brownbanded cockroach Supella longipalpa (Orthoptera: Blattellidae) has been identified as 5-(2',4'-dimethylheptanyl)-3-methyl-2H-pyran-2-one, supellapyrone; the stereochemistry of this pheromone was not elucidated, but it was demonstrated that the pheromone consists of, at most, two enantiomers (6). Our interest in developing synthetic methodologies for the direct joining of a side chain to pyrones led us to use a Pd-catalyzed coupling technique to elucidate the stereochemistry of supellapyrone. However, the fact that the nonnatural stereoisomers were already known neither to appreciably synergize nor to strongly inhibit male response (6) suggested that the synthetic approach alone would be unlikely to succeed. We now report the application of GC (using achiral and chiral columns), coupled with electroantennographic detection (EAD), to establish that natural supellapyrone has the 2'R,4'R configuration.MATERIALS AND METHODS Analytical ...

Unusual macrocyclic lactone sex pheromone of Parcoblatta lata , a primary food source of the endangered red-cockaded woodpecker

“…Several highly attractive epoxygermacranoid compounds have been identified from various Periplaneta and Blatta species (family Blattidae), and these compounds, in various blends, also appear to function in reproductive isolation (13)(14)(15)(16)(17). An exceptionally attractive α-pyrone (supellapyrone) was identified from the brown-banded cockroach Supella longipalpa (Blattellidae, Pseudophyllodromiinae), and this pheromone appears to function as a single compound and not as part of a pheromone blend (18)(19)(20). A substituted quinone (blattellaquinone), from the German cockroach Blattella germanica (Blattellidae, Blattellinae) (21), represents another chemical class.…”

Molecular receptive ranges of olfactory receptor neurones responding selectively to terpenoids, aliphatic green leaf volatiles and aromatic compounds, in the strawberry blossom weevil Anthonomus rubi

“…Whereas enantioselective RNs for pheromones have been described in several insect species (Mustaparta et al 1980;Hansen et al 1983;Leal et al 1995;Larsson et al 1999), enantioselectivity of plant odour RNs has been only recently reported in a few cases (Wibe et al 1998;Stranden et al 2002Stranden et al , 2003aBichão et al 2005, Røstelien et al 2005. Behavioural discrimination of enantiomers has been shown in insects (Tooker et al 2002;Borg-Karlson et al 2003).…”

The 2013 Benjamin Franklin Medal in Chemistry presented to Jerrold Meinwald, Ph.D.

“…27, Fig. 10) from the brownbanded cockroach [28]. In this approach, a dissected antenna from the cockroach was attached to wire leads, and the electrical impulses recorded in response to chemical stimuli.…”