Characterization and synthesis of volatile compounds from the defensive secretions of some "daddy longlets" (Arachnida: Opiliones: Leiobunum spp.).

Abstract

Analyses of the chief volatile constituents of the defensive secretions of three oplionids were carried out. Leiobunum nigripalpi produces three closely related C7 compounds: E-4methyl-4-hexen-3-one(I), 4-methylhexan-3-one(II), and 4-methylhexan-3-ol(III), along with E4methyl hepten-3-one(IV), EE-2,4-dimethylhexa-2,4-diena(IX), and a minor, unidentified component. L. leiopenis secretion contains E4 methylWhepten-3-one(IV), 4-methylheptan-3-one(V), EE-2,4-dimethylhexa-2,4-dien-1-ol(VII), and EE-2,4-dimethylhepta-2,4-dien-1-ol(VIII). L. calcar yields chiefly E-4,6-dimethyl--octen-3-one(VI) and E,E.2,4-dimethylhexa-2,4-dien--l(VoI4 Six of these compounds are new natural products. The structures of these compounds, which can be regarded either as polyketide-derived or as modified isoprenoids, raise interesting biosynthetic questions.Recent studies of the defensive secretions of arachnids of the order Opiliones have led to the characterization of a small family of volatile, acyclic ketones from seven species within the suborder Palpatores (1-3). We have now carried out a study of the defensive compounds from three members of the genus Leiobunum within this suborder. Each of the species examined produces a mixture of at least three to five volatile organic components. These all proved to be based on n-hexane, nheptane, or n-octane skeletons bearing one or two methyl substituents, and incorporating zero, one, or two double bonds, along with a single oxygen function either as a carbonyl group or as an hydroxyl group.Our findings are summarized in Table 1, which gives the structures of the nine compounds characterized, along with the relative amounts of these compounds in the secretions.Because of the small quantities of secretion available for study, our chief analytical tool was the computer-controlled gas chromatography/mass spectra (GC/MS). In three cases (II, V, and VI), the observed mass spectra served to identify a given component directly; comparison with authentic samples confirmed these identifications. In the six remaining instances (I, III, IV, VII, VIIL and IX), the mass spectra were only suggestive. Structures could be guessed, however, based on these spectral data considered along with the results of some simple chemical transformations, and were confirmed by direct comparisons with independently synthesized materials. The experimental details are given in the section that follows. EXPERIMENTAL Gas chromatographic analyses were carried out on a Varian model 2100 gas chromatograph using a 215 m X 2 mm column packed with 5% OV-1 on Gas-Chrom Q(column A), OV-225 RESULTS L. nigripalpiThe secretion obtained from individuals of both sexes of L. nigripalpi was collected directly in glass capillaries and examined by GC and by GC/MS. Five components were characterized. The mass spectra of E-4-methyl-4-hexen-3-one(I), *4-methylhexan-3-one(II), 4-methylhexan-3-ol(III), E-4-methyl-4-hepten-3-one(IV), and E,E-2,4-dimethylhexa-2,4-dienal(IX) were identical with those obtained from the synthetic compounds (dide ...

Defensive substances of opilionids

“…Given this chemical dichotomy at the subordinal level, as well as the considerable chemical diversity already apparent at the generic and specific levels, it seems likely tl~at an in-depth study of opilionid secretions will eventually have phyletic and taxonomic implications. As part of our ongoing study of opilionid chemistry Jones et al, 1976Jones et al, , 1977Meinwald et al, 1971;Wiemer et al, 1978), we here report on the secretory composition of four neotropical laniatores, two of the family Cosmetidae, and two of the Gonyleptidae.…”

Caste-dependent pheromones in the head of the antTetramorium caespitum

“…Both compounds have also been reported in the defensive secretion of Opiliones (Jones et al, 1977), and the ketone in the defensive secretion ofa staphylinid beetle (Fish and Pattenden, 1975). 4-Methyl-3-hexanol is a new pheromone -for ants, but its occurrence is not surprising, since ketones and the corresponding alcohols are usually found together.…”

Estudo comparado da morfologia da região do ozóporo de opiliões Laniatores (Arachnida, Opiliones)

“…Originalmente chamada de gonyleptidina por Estable et al (1955), é amplamente utilizada como uma ferramenta para suas defesas, e seu potencial já foi testado várias vezes, inclusive lançando mão de diversos possíveis predadores, tais como várias espécies de formigas e algumas aranhas, por exemplo, tanto testando com o indivíduo secretando a substância de defesa, quanto à irritabilidade da substância por si só (Cloudsey-Thompsonm 1968; Blum & Edgar, 1971;Eisner et al, 1971;Eisner et al, 1978;Jones et al, 1977;Blum, 1981;Acosta et al, 1993;Eisner et al, 2004;Machado et al, 2000Machado et al, , 2002Machado et al, , 2005.…”

“…Eupnoi e Dyspnoi, por sua vez, comumente sintetizam cadeias curtas acíclicas com cetonas, aldeídos e álcoois ou também naftoquinonas (Blum et al, 1968;Blum & Edgar, 1971;Jones et al, 1976Jones et al, , 1977Meinwald et al, 1971;Wiemer et al, 1978, Ekpa et al, 1985. Jones et al (1977) também chamaram a atenção para o fato de haver variabilidade na composição da secreção em indivíduos diferentes, apesar de serem pertencentes à mesma espécie.…”

“…Jones et al (1977) também chamaram a atenção para o fato de haver variabilidade na composição da secreção em indivíduos diferentes, apesar de serem pertencentes à mesma espécie.…”