Defensive Spiroketals from Emphasis Type="Italic"

Authors: Aaron T Dossey John M Whitaker Maria Cristina A Dancel Robert K Vander Meer Ulrich R Bernier Marco Gottardo William R Roush

Publish Date: 2012/09/14

Volume: 38, Issue: 9, Pages: 1105-1115

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Abstract

Insects are the largest and most diverse group of organisms on earth with over 1000000 species identified to date Stick insects “walkingsticks” or “phasmids” Order Phasmatodea are known for and namederived from their camouflage that acts as a primary line of defense from predation However many species also possess a potent chemical defense spray Recently we discovered that the spray of Asceles glaber contains spiroketals a confirmed major component 2S6R−E2methyl17dioxaspiro55undecane and a tentatively identified minor component 2ethyl16dioxaspiro45decane and glucose In this paper we 1 illustrate the identification of spiroketals and glucose in the defense spray of A glaber by using Nuclear Magnetic Resonance NMR Gas Chromatography/Mass Spectrometry GC/MS and comparison with a synthetic reference sample 2 provide the elucidation of the absolute configuration of the major spiroketal in that defense spray and 3 demonstrate the effect of this compound and its enantiomer on both fire ants Solenopsis invicta and mosquitoes Aedes aegyptiWe thank James R Rocca at the Advanced Magnetic Resonance Imaging and Spectroscopy University of Florida for technical assistance on NMR experiments We also thank David Milne and Michele Hosack for conducting fire ant bioassays ATD thanks Dr Spencer S Walse USDAARS for lending the enantiomer selective GC column NMR data were collected in the AMRIS facility in the McKnight Brain Institute of the University of Florida Funding was provided by the NSFsupported National High Magnetic Field Laboratory University of Florida and NIH Grant GM026782 WRR Scripps FloridaSupplemental Material Available online S1 GC/MS Chromatograms of all natural samples of Asceles glaber defense spray analyzed S2 Mass spectra of A glaber defense spray samples and synthetic spiroketal 1 S3 TIC for A glaber chemical defense spray S4 The EI mass spectra for A glaber chemical defense spray S5 TIC and mass spectrum of synthetic spiroketal 1 S6 The NIST EI Mass Spectral Library search identified the minor peak in A glaber defense spray S7 The NIST EI Mass Spectral Library search for the major peak for A glaber chemical defense spray S8 1D 1H NMR spectral overlays of natural A glaber defense spray and synthetic spiroketal 1 In benzened6 S9 NMR spectra of A glaber defense spray extracted with benzened6 S10 NMR spectra of synthetic spiroketal 1 S11 EI mass spectra from enantiomer selective GC/MS analysis of A glaber chemical defense spray and synthetic spiroketal 1 S12 External calibration curves from the GC/MS of synthetic spiroketal 1 for quantification of that compound in A glaber chemical defense spray S13 Extended table of concentrations of spiroketal 1 in A glaber chemical defense spray S14 1D 1H NMR spectral stack plots of natural A glaber chemical defense spray and authentic DGlucose dissolved in D2O S15 NMR spectra of A glaber defense spray dissolved in D2O S16 NMR spectra of synthetic spiroketal 1 dissolved in D2O and S17 NMR spectra of authentic DGlucose dissolved in D2O

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