Synthesis of all four stereoisomers of 5-hydroxy-4-methyl-3-heptanone using plants and oyster mushrooms

All four possible stereoisomers of 5-hydroxy-4-methyl-3-heptanone were synthesized from common achiral reagents using fast, straightforward organic synthesis, including the use of whole tissue of Daucus carota, Solanum melongena, and Pleurotus ostreatus

Vegetables as biocatalysts in stereoselective hydrolysis of labile organic compounds

Hydrolysis of labile esters of β-hydroxyketones has been performed with whole plant tissue from various vegetables. The pheromone 5-hydroxy-4-methyl-3-heptanone (1) was used as the model compound. Hydrolysis of acetates and benzoates of 1 was unsuccessf

Behavioral and Electrophysiological Responses of Triatoma brasiliensis Males to Volatiles Produced in the Metasternal Glands of Females

In many insects, mate finding is mediated by volatile sex pheromones, but evidence for this phenomenon in triatomines (Heteroptera: Reduviidae) is still fragmentary. Recently, it was shown that metasternal glands (MGs) are involved in producing signals related to the sexual communication of Triatoma infestans and Rhodnius prolixus. Based on this, we tested whether MG volatiles could be involved in the sexual communication of Triatoma brasiliensis. Odor-mediated orientation responses were studied by using a T-tube olfactometer. These tests showed that males exhibit positive anemotaxis when confronted with adult odor-laden air currents. Moreover, females that had their metasternal glands occluded did not elicit significant orientation by males. Compounds produced by the MGs of T. brasiliensis females were identified by means of SPME, GC-FID, and GC-MS, with achiral and chiral columns. All substances identified were ketones and alcohols, and similar compound profiles were found in the secretions produced by both sexes. The most abundant compounds identified were 3-pentanone, followed by (4R)-methyl-1-heptanol, 3-pentanol, and (2S)-methyl-1-butanol. In addition, GC-EAD recordings showed that the antennae of males responded to several of the main components of female MG secretions. Our results showed that compounds produced by the MGs of T. brasiliensis females are involved in the sexual communication of this species

Metasternal Gland Volatiles and Sexual Communication in the Triatomine Bug, Rhodnius prolixus

Twelve compounds produced by the metasternal glands (MGs) of the triatomine bug Rhodnius prolixus were identified by solid phase microextraction (SPME) combined with coupled gas chromatography-mass spectrometry (GC-MS) using achiral and chiral columns. All substances were ketones or alcohols, and the same compound profile was found in the secretions produced by either sex. The most abundant compounds were 2-methyl-3-buten-2-ol, (2S)-pentanol, (3E)-2-methyl-3-penten-2-ol, and (2R/2S)-4-methyl-3-penten-2-ol. Emission of these compounds was detected more frequently from females than males, and females released them more frequently during the early hours of the scotophase, the period when sexual activity in this species is at its peak. These compounds were also detected in the headspace above mating pairs. Finally, the occlusion of the MG orifices of male or female bugs with paraffin resulted in a significant decrease in copulation frequency compared to sham-operated insects. Together, these data suggest that the MG secretions of R. prolixus may be involved in sexual communication

Structure-Activity Relationships of Phenylpropanoids as Antifeedants for the Pine Weevil Hylobius abietis<i/>

Ethyl cinnamate has been isolated from the bark of Pinus contorta in the search for antifeedants for the pine weevil, Hylobius abietis. Based on this lead compound, a number of structurally related compounds were synthesized and tested. The usability of the Topliss scheme, a flow diagram previously used in numerous structure-activity relationship (SAR) studies, was evaluated in an attempt to find the most potent antifeedants. The scheme was initially followed stepwise; subsequently, all compounds found in the scheme were compared. In total, 51 phenylpropanoids were tested and analyzed for SARs by using arguments from the field of medicinal chemistry (rational drug design). Individual Hansch parameters based on hydrophobicity, steric, and electronic properties were examined. The effects of position and numbers of substituents on the aromatic ring, the effects of conjugation in the molecules, and the effects of the properties of the parent alcohol part of the esters were also evaluated. It proved difficult to find strong SARs derived from single physicochemical descriptors, but our study led to numerous new, potent, phenylpropanoid antifeedants for the pine weevil. Among the most potent were methyl 3-phenylpropanoates monosubstituted with chloro, fluoro, or methyl groups and the 3,4-dichlorinated methyl 3-phenylpropanoate

Potential of a blend of E8, E10-120H and E8-12Ac for mating disruption of codling moth, Cydia pomonella L. (Lep. Tortricidae)

Dispensers of E8,E 10- 120H (codlemone), E8,E 10-12Ac (codlemone acetate), or both dispenser types were placed on the corners of 100 m’ and 300 m’ plots within apple orchards. Communication disruption of male codling moths, Cydia pomonella, was monitored with pheromone traps in the centres of these plots. In the 300 m2 plots, trap catch was reduced only by codlemone. In the 100 m’ plots, trap catch was reduced in all three treatments, fewest males were caught in plots treated with both codlemone and codlemone acetate. Males were attracted to codlemone dispensers, they were also flying actively around the tree crowns, well above the dispensers. This behaviour was not observed in treatments with codlemone acetate, where male orientation flights were directed only towards the trap in the plot centre. The antagonistic effect of each of the four geometric isomers of codlemone acetate was shown by another trap test. Addition of 20% E,E-; E,Z-; Z,E- or Z8,ZIO-I2Ac decreased male attraction to traps baited with E8, E10-120H

Quantitative Structure-Activity Relationships of Pine Weevil Antifeedants, a Multivariate Approach

Antifeedant activity of mainly phenylpropanoic, cinnamic, and benzoic acids esters was tested on the pine weevil, Hylobius abietis (L.). Of 105 compounds screened for activity, 9 phenylpropanoates, 3 cinnamates, and 4 benzoates were found to be highly active antifeedants. To understand the structure-activity relationships of these compounds, a multivariate analysis study was performed. A number of molecular and substituent descriptors were calculated and correlated to results from two-choice feeding tests with H. abietis. Three local models were developed that had good internal predictive ability. External test sets showed moderate predictivity. In general, low polarity, small size, and high lipophilicity were characteristics for compounds having good antifeedant activity

(11z,13E)-Hexadecadien-1-yI Acetate: Sex Pheromone of the Grass Webworm Herpetogramma licarsisalis - Identification, Synthesis, and Field Bioassays

The grass webworm Herpetogramma licarsisalis (Lepidoptera: Crambidae), which has recently established in pasture in Northland, New Zealand, is an important pest of many tropical and subtropical grasses. Two pheromone components, (Z)-11-hexadecen-1-yl acetate (Z11-16:Ac) and (11Z,13E)- hexadecadien-1-yl acetate (Z11,E13-16:Ac), were identified in pheromone gland extracts of female moths by gas chromatography (GC), GC-electroantennographic detection, and GC-mass spectrometry in conjunction with microchemical tests (dimethyldisulfide and 4-methyl-1,2,4-triazoline-3,5-dione derivatizations). Z11,E13-16:Ac and its geometric isomer (11E,13Z)-hexadecadien-1-yl acetate (E11,Z13-16:Ac) were synthesized via stereoselective Wittig reactions, and the identity of the diene present in the pheromone glands was confirmed to be Z11,E13-16:Ac. Field bioassays at Indooroopilly in Brisbane, Australia, established that Z11,E13-16:Ac was necessary and sufficient for attraction of male grass webworm moths and that the corresponding alcohol, (11Z,13E)-hexadecadien-1-ol (Z11,E13-16:OH), had a strong inhibitory effect on trap catches at the ratios tested. When mixed with Z11,E13-16:Ac in various ratios, Z11-16:Ac had no effect on the attractiveness of lures