Composition of the Defensive Secretion in Three Species of European Millipedes

Three European julid species, Cylindroiulus boleti, Leptoiulus trilineatus, and Megaphyllum bosniense, secrete mixtures of up to 12 different quinones. The major components in these species are 2-methoxy-3-methyl-1,4-benzoquinone and 2-methyl-1,4-benzoquinone. 2-Methoxy-5-methylhydroquinone is detected for the first time in the Class Diplopoda. 2-Hydroxy-3-methyl-1,4-benzoquinone, 2,3-dimethoxyhydroquinone, 2-methyl-3,4-methylendioxyphenol, and 2,3-dimethoxy-5-methylhydroquinone are registered for the first time in representatives of the family Julidae. The similar chemical composition of defense secretions in all analyzed European julids and Pacific spirobolids supports the idea of the chemical consistency of defensive compounds in juliform millipedes.     

Millipedes That Smell Like Bugs: (E)-Alkenals in the Defensive Secretion of the Julid Diplopod Allajulus Dicentrus

The secretions from serial defensive glands of the Austrian diplopod Allajulus dicentrus (Julidae, Cylindroiulini) were extracted and analyzed by means of gas chromatography - mass spectrometry. In adults, 13 components from two chemical classes were detected: 1) The common juliform benzoquinones were represented by four compounds (2-hydroxy-3-methyl-1,4-benzoquinone, 2-methoxy-3-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, and 2,3-dimethoxy-5-methyl-1,4-benzoquinone). From this series, 2-methoxy-3-methyl-1,4-benzoquinone was most abundant, comprising about 40?% of the whole secretion. 2) All remaining compounds were identified as aliphatic (E)-alkenals [(E)-2-heptenal, (E)-2-octenal, (E)-2-nonenal, (E)-2-decenal)] along with their corresponding alcohols. (E)-2-Octenal was most abundant, roughly accounting for another 35?% of the secretion. In juveniles, different stages in the ontogenetic development of the secretion were observed, with early instars (stadium III and IV) exclusively containing the benzoquinone fraction. Alkenols and alkenals were added in later instars (stadium V and VI), with secretions of stadium VI-juveniles being already similar to those of adults. Representatives of Spirostreptida, Spirobolida, and Julida traditionally have been considered to produce benzoquinonic secretions only ("quinone millipedes"), and information on secretion components from other chemical classes is still scarce. We here provide evidence for the participation of non-quinonic compounds in the defensive exudates of the Cylindroiulini. The occurrence of additional, non-quinonic compounds in certain species within a chemically homogenous, benzoquinone-producing taxon indicates the rapid adoption of novel exocrine compounds, possibly in order to meet the demands in a changed ecological environment.     

Quinones and phenols in the defensive secretions of neotropical opilionids

Three quinones (2,3-dimethyl-1,4-benzoquinone; 2,5-dimethyl 1,4-benzoquinone; and 2,3,5-trimethyl-1,4-benzoquinone) and two phenols (2,3-dimethylphenol and 2-methyl-5-ethylphenol) were isolated from the defensive secretions of four species of opilionids (suborder Laniatores) from the Canal Zone. Phenols had not previously been reported from opilionids, and 2-methyl-5-ethylphenol was not known as a natural product. The secretions, which are mixed with regurgitated enteric fluid upon discharge, are administered by the animals by leg dabbing.Paper no. 53 of the seriesDefense Mechanisms of Arthropods.     

Defensive substances of opilionids

Two quinones (2,3-dimethyl-1,4-benzoquinone and 2,3,5-trimethyl-1,4-benzoquinone) and three phenols (2,3-dimethylphenol, 2-methyl-5-ethylphenol, and 2,3,4-trimethylphenol) were isolated from the defensive secretions of opilionids (Laniatores) from the Panama Canal Zone. The trimethylphenol was not previously reported as a natural product.Paper no. 64 of the seriesDefense Mechanisms of Arthropods. Paper no. 63 is: Goetz, M., Wiemer, D.F., Haynes, L.H., Meinwald, J., and Eisner, T.Helvetica Chimica Acta, 62:1396–1400 (1979).     

Lubricity-Enhancing Low-Temperature Diesel Fuel Additives

Branched chain alkyl esters have lower crystallization temperatures than those with straight chain headgroups. We investigated the effect of branched chain headgroups on the cold flow properties and lubricity of alkyl esters. Commercial grade canola methyl ester was transformed into branched chain alkyl esters through a two or three-stage base-catalyzed transesterification reaction with 1-methoxy-2-propanol and 3-methyl-1-butanol. Conversion rates between 85 and 95% were achieved. The alkyl esters exhibited improved cold flow properties. The pour points were reduced from −12 to −27 °C as a result of incorporating branched headgroups. Addition of 0.1 or 0.2% (v/v) 1-methoxy-2-propyl alkyl ester improved the lubricity of a commercial pre-production ultra low sulfur diesel (ULSD) fuel, as determined by increased lubricity number and reduced wear scar diameter. The inclusion of methyl-tert butyl ether or ethanolamides additives to ULSD containing alkyl esters had an antagonistic effect on lubricity. The branched-chain alkyl esters have the potential to be used as lubricity-enhancing and low-temperature fuel additives.     

Millipede Defensive Compounds Are a Double-Edged Sword: Natural History of the Millipede-Parasitic Genus <Emphasis Type="Italic">Myriophora</Emphasis> Brown (Diptera: Phoridae)

Toxic defensive secretions produced by millipedes in the orders Julida, Spirobolida, Spirostreptida, and Polydesmida are highly repellent to most vertebrate and invertebrate natural enemies, but a few insects have evolved mechanisms to overcome these defenses. We demonstrate that highly specialized parasitic phorid flies in the species-rich genus Myriophora use volatile millipede defensive compounds as kairomones for host location. Of the two predominant quinone components in the defensive blend of juliform millipedes, 2-methoxy-3-methyl-1,4-benzoquinone alone was sufficient to attract adult flies of both sexes; however, a combination of 2-methoxy-3-methyl-1,4-benzoquinone and 2-methyl-1,4-benzoquinone increased attractiveness nearly threefold. We further discuss oviposition behavior, adult and larval feeding habits, life history parameters, and the potential competitive interactions between phorid flies in the genus Myriophora and other millipede-associated insects.     

Molecular analysis of intact preen waxes of Calidris canutus (Aves: Scolopacidae) by gas chromatography/mass spectrometry

The intact preen wax esters of the red knot Calidris canutus were studied with gas chromatography/mass spectrometry (GC/MS) and GC/MS/MS. In this latter technique, transitions from the molecular ion to fragment ions representing the fatty acid moiety of the wax esters were measured, providing additional resolution to the analysis of wax esters. The C₂₁−C₃₂ wax esters are composed of complex mixtures of hundreds of individual isomers. The odd carbon-numbered wax esters are predominantly composed of even carbon-numbered n-alcohols (C₁₄, C₁₆, and C₁₈) esterified predominantly with odd carbon-numbered 2-methyl fatty acids (C₇, C₉, C₁₁, and C₁₃), resulting in relatively simple distributions. The even carbon-numbered wax esters show a far more complex distribution due to a number of factors: (i) Their n-alcohol moieties are not dominated by even carbon-numbered n-alcohol moieties are not dominated by even carbon-numbered n-alcohols esterified with odd carbon-numbered 2-methyl fatty acids, but odd and even carbon-numbered n-alcohols participate in approximately equal amounts; (ii) odd carbon-numbered methyl-branched alcohols participate abundantly in these wax ester clusters; and (iii) with increasing molecular weight, various isomers of the 2,6-, 2,8-, and 2,10-dimethyl branched fatty acids also participate in the even carbon-numbered wax esters. The data demonstrate that there is a clear biosynthetic control on the wax ester composition although the reasons for the complex chemistry of the waxes are not yet understood.     

A study of the structures and reactions of some methyl substituted unsaturated C18 ester intermediates in the synthesis of a racemic mixture of 10-methyloctadecanoic acid

Methyl 10-undecenoate was hydrated to methyl 10-hydroxyundecanoate using mercury (II) acetate in aqueous tetrahydrofuran (THF). Chromic acid oxidation of methyl 10-hydroxyundecanoate gave methyl 10-oxoundecanoate, which was hydrolyzed to 10-oxoundecanoic acid. Reaction of n-octyl magnesium bromide complex in THF with 10-oxoundecanoic acid furnished 10-hydroxy-10-methyloctadecanoic acid after hydrolysis. The latter compound was esterified, and dehydration of methyl 10-hydroxy-10-methyloctadecanoate withp-toluenesulfonic acid in benzene gave a mixture of unsaturated branched fatty ester intermediates:viz. methyl 10-methyl-9-octadecenoate, 10-methyl-10-octadecenoate and 10-octyl-10-undecenoate. Treatment of the mixture of unsaturated branched fatty ester intermediates with mercury (II) acetate in methanol gave exclusively methyl 10-methoxy-10-methyloctadecanoate. Epoxidation of the same mixture of unsaturated fatty esters withm-chloroperbenzoic acid provided a mixture of epoxy derivatives: methyl 9,10-epoxy-10-methyloctadecanoate, 10,11-epoxy-10-methyloctadecanoate and 2-octyl-oxirane-nonanoate. Catalytic hydrogenation of the mixture of unsaturated fatty esters gave a racemic mixture of methyl 10-methyloctadecanoate, which was hydrolyzed to 10-methyloctadecanoic acid. The structures of the mixture of unsaturated branched fatty ester intermediates and their derivatives were characterized by chemical and spectroscopic analyses.     

Some fatty esters as plasticizers and fungicides for natural rubber

The prepared n-fatty alcohols from petroleum sources are esterified with a dibasic acid series (malonic, succinic, glutaric and adipic) or phthalic anhydride, giving the corresponding C₁₂ fatty esters. The prepared C₁₂ fatty esters were formulated with natural rubber. The drying time, some mechanical properties and fungitoxicity of the prepared film samples were examined. The conventional dibutyl phthalate plasticizer was used for the purpose of comparison. The data obtained indicate that the prepared fatty esters can be used as plasticizers with antifungal activity for natural rubber. ©1997 SCI     

Defensive and pheromonal secretion of the tergal gland of Aleochara curtula

The defensive secretion from the tergal gland of the staphylinid beetle,Aleochara curtula, acting as a supplementary mating stimulant, was investigated by gas-liquid chromatography, mass spectrometry, and IR spectroscopy. The reservoir contains a complex mixture of hydrocarbons, aliphatic aldehydes, and substituted 1,4-benzoquinones.n-Undecane, 1-undecene, and (Z)-4-tridecene were identified as the major hydrocarbon components. The main aldehydes aren-dodecanal and (Z)-5-tetradecenal, and the chief quinones are toluquinone and 2-methoxy-3-methyl-1,4-benzoquinone, the latter being established structurally by comparison of the mass spectra of the three synthesized isomers. Quantitative GLC analyses revealed no sex specificity of the relative concentrations of the compounds.Coleoptera: Staphylinidae (Aleocharinae)     

Naphthoquinones and Anthraquinones from Scent Glands of a Dyspnoid Harvestman, <Emphasis Type="Italic">Paranemastoma quadripunctatum</Emphasis>

Extracts of Paranemastoma quadripunctatum (Opiliones, Dyspnoi, Nemastomatidae) contained seven components, all of which likely originated from the secretion of well-developed prosomal scent glands. The two main components (together accounting for more than 90% of the secretion) were identified as 1,4-naphthoquinone and 6-methyl-1,4-naphthoquinone. The minor components were 1,4-naphthalenediol, two methoxy-naphthoquinones (2-methoxy-1,4-naphthoquinone, and 2-methoxy-6-methyl-1,4-naphthoquinone) and two anthraquinones (2-methyl-9,10-anthraquinone and a dimethyl-9,10-anthraquinone). While some chemical data on scent gland secretions of the other suborders of Opiliones (Cyphophthalmi, palpatorean Eupnoi, and Laniatores) already exist, this is the first report on the scent gland chemistry in the Dyspnoi. Naphthoquinones are known scent gland exudates of Cyphophthalmi and certain Eupnoi, methoxy-naphthoquinones and anthraquinones are new for opilionid scent gland secretions.     

Biochemical and physiological studies of certain ticks (Ixodoidea): Isolation and partial identification of a new fatty acid in eggs ofDermacentor andersoni Stiles (Ixodidae)

Gas liquid chromatographic analysis of the fatty acid methyl esters from eggs ofDermacentor andersoni Stiles (Ixodidae) revealed the presence of significant quantities (15% total fatty acids) of an unidentified component with a retention time between C_18∶3−C_22∶0 fatty acids. Smaller amounts of the unidentified component (ca. 5% total fatty acid) also were detected in host rabbit serum. Purified, the unidentified component's methyl ester collected from the tick eggs by preparative gas liquid chromatography was partially identified and characterized by chemical and spectroscopic analyses. The evidence suggests that the unidentified component is a methyl branched C₁₅ tricarboxylic acid containing two vicinal carboxylic acid groups. Biosynthesis of the unidentified component by the tick is under investigation.     

The fatty acids of wax esters and sterol esters from vernix caseosa and from human skin surface lipid

Separation of sterol esters from wax esters in the lipids of vernix caseosa and adult human skin surface was accomplished by column chromatography on MgO. The fatty acids of the sterol esters and wax esters of both samples were separated into saturates and monoenes, and examined in detail by gas liquid chromatography (GLC). The saturated fatty acids of the wax esters of vernix caseosa and of adult human skin surface were remarkably similar. They ranged in chain length from at least C₁₁ to C₃₀, six skeletal types being present: straight even, straight odd, iso, anteiso, other monomethyl branched and dimethyl branched. A large number of patterns of monoenes were observed, each pattern consisting of desaturation of a specific chain at Δ6 or Δ9 plus its extension or degradation products. The mole per cent of the total Δ6 and Δ9 patterns of wax ester fatty acid monoenes of vernix caseosa were 87% and 12%, respectively, and 98% and 1%, respectively, for adult human skin surface lipid. The sterol ester fatty acids of vernix caseosa were much different from those of adult human skin surface: vernix caseosa saturates were largely branched and of lengths greater than C₁₈, whereas the saturates of adult human surface lipid resembled the wax ester fatty acids. Of the vernix caseosa monoene patterns, the mole per cent was 30% Δ6 and 70% Δ9, whereas of the adult human skin surface sterol ester fatty acids 89% were Δ6 and 11% Δ9. Chain extension was particularly pronounced in the sterol ester fatty acid monoenes of vernix caseosa amounting to 7–8 C₂ units in some cases. The fatty acids of the sterol esters of both vernix caseosa and adult human skin surface appear to be derived from the sebaceous gland and from the keratinizing epidermis, but those of the wax esters are from the sebaceous glands only.     

Chemical Defense in Harvestmen (Arachnida,Opiliones): Do Benzoquinone Secretions Deter Invertebrate and Vertebrate Predators?

Two alkylated 1,4-benzoquinones were identified from the defensive secretion produced by the neotropical harvestman Goniosoma longipes (Gonyleptidae). They were characterized as 2,3-dimethyl-1,4-benzoquinone and 2-ethyl-3-methyl-1,4-benzoquinone. We tested the effectiveness of these benzoquinone secretions against several predator types, including invertebrates and vertebrates. Different predators were exposed to the harvestmen's gland secretion or to distilled water in laboratory bioassays. Our results indicate that secretions containing the 1,4-benzoquinones released by G. longipes can be an effective defense against predation, and that the effectiveness of the secretion is dependent on the predator type. The scent gland secretion repelled seven ant species, two species of large wandering spiders, and one frog species, but was not an effective defense against an opossum. Our study also demonstrates that the scent gland secretion of G. longipes can work as a chemical shield preventing the approach of three large predatory ants for at least 10 min. The chemical shield may protect the harvestman against successive attacks of the same ant worker and also allow the harvestman to flee before massive ant recruitment. Our data support the suggestion that chemical defenses may increase survival with some but not all potential predators. This variation in defense effectiveness may result from many interacting factors, including the attack strategy, size, learning ability, and physiology of the predators, as well as the chemical nature of the defensive compounds, type of emission, and amount of effluent released by the prey.     

Synthesis of fatty acid esters from acid oils using lipase B from Candida antarctica

Esterification of corn and sunflower acid oils with straight‐ and branched‐chain alcohols were conducted using lipase B from Candida antarctica (Novozym 435) in n‐hexane. Sunflower acid oil consisted of 55.6% free fatty acids and 24.7% triacylglycerols, while the free fatty acids and triacylglycerols contents of corn acid oil were 75.3% and 8.6%, respectively. After 1.5 h of methanolysis of sunflower acid oil, the highest fatty acid methyl ester content (63.6%) was obtained at 40 °C and the total fatty acid/methanol molar ratio was 1/1, using 15% enzyme based on acid oil weight. The conversion of both acid oils with straight‐ and branched‐chain alcohols was not significantly affected by the chain length of the alcohols. However, the lowest fatty acid methyl ester content (50%) was obtained in the reaction of corn acid oil with methanol. Sunflower acid oil was converted to fatty acid esters using primer alcohols such as n‐propanol, i‐ and n‐butanol, n‐amylalcohols, n‐octanol, and a mixture of amylalcohol isomers, resulting in a fatty acid ester content of about 70% at 40 °C.     

ANOINTING CHEMICALS AND ECTOPARASITES: EFFECTS OF BENZOQUINONES FROM MILLIPEDES ON THE LONE STAR TICK, <Emphasis Type="Italic">Amblyomma americanum</Emphasis>

Many mammals and birds roll on or rub themselves with millipedes that discharge benzoquinones. Chemicals transferred from millipedes onto the integument of anointing animals are thought to deter ectoparasites. We tested the lone star tick, Amblyomma americanum(L.), for responses to three widespread components of millipede defensive secretions, 1,4-benzoquinone; 2-methyl-1,4-benzoquinone (toluquinone); and 2-methoxy-3-methyl-1,4-benzoquinone (MMB). In toxicity tests, ticks were confined for 1 hr in filter-paper packets treated with serial dilutions of each of the benzoquinones or the commercial acaricide permethrin. Ticks were least affected by toluquinone, and most affected by permethrin. Of the benzoquinones, only MMB showed repellent activity. Behavioral assays were more sensitive than mortality for measuring the effects of the benzoquinones. Latencies for ticks to right themselves and to climb were greater with all compounds, even at the lowest concentrations, than with controls. Ticks exposed to low concentrations of benzoquinones appeared to recover over time, whereas those exposed to high concentrations exhibited behavioral abnormalities 1–3 mo later. Our results indicate that benzoquinones appropriated via anointing may reduce the tick loads of free-ranging animals, although key questions remain on the amounts of these compounds available to and effectively appropriated by anointing animals.     

Volatile Components in Dorsal Gland Secretions of the White-Lipped Peccary, Tayassu pecari, from Bolivia

Secretions from the dorsal gland of male and female free-ranging adult white-lipped peccaries (Tayassu pecari) from Bolivia were analyzed by gas chromatography–mass spectrometry. Fifty compounds were identified, some provisionally. Secretions of both sexes contain saturated and unsaturated C₅–C₁₈ carboxylic acids as well as isomers of the diterpene springene. The females' secretions uniquely possess farnesyl esters of C₈ and C₁₀ carboxylic acids, whereas the males' secretions uniquely showed two compounds provisionally identified as monounsaturated C₁₆ lactones. Saturated high-molecular-weight esters of C₁₀ carboxylic acids are more abundant in the females' secretions than in those of the males. The secretions of both sexes also contain monoalkanoate esters of methylhydroquinone as major components.     

New method for controlled synthesis of polylactide block copolymers: organoborane/p-quinone system and reversible-deactivation radical polymerization

We developed a new approach to obtain polylactide hybrid block copolymers with vinyl monomers (styrene, methyl methacrylate, methyl acrylate) through the realization of a reaction sequence using triethylborane and various p-quinones. The method offered includes two stages. In the first stage, a chain-transfer agent was obtained by borylation of the terminal hydroxyl groups of polylactide. The second stage was vinyl monomer radical polymerization in the presence of p-quinone accompanied by S_H2-substitution at the boron atom.1,4-Naphthoquinone, 2,3-dimethyl-1,4-benzoquinone, duroquinone and 2,5-di-tert-butyl-1,4-benzoquinone were used as synthetic polymer chain growth mediators. It is shown that 1,4-naphthoquinone and 2,3-dimethyl-1,4-benzoquinone, similar in their characteristics, are effective agents providing the realization of reversible-deactivation radical polymerization. Realization of reversible-deactivation radical polymerization was proved with the analysis of the kinetics of block copolymerization, molecular weight characteristics and compositional homogeneity of block copolymers as well as its further capability to elongate the polymer chain. Synthesized block copolymers have a high thermal stability compared to the initial borylated polylactide. © 2021 Society of Industrial Chemistry.     

Skin surface lipids of the dog

The skin surface lipid of the dog has been reported to contain a high proportion of diol diesters having a lower mobility on thin layer chromatography than diesters from other species in spite of containing similar fatty acid and diol components. In the present study, dog skin surface lipid was separated by preparative thin layer chromatography into sterol esters (42%), wax diesters (32%), free sterols (9%), polar lipids (7%), and unidentified components (10%). The diesters contained 1,2-diols, each esterified with one long chain fatty acid and one isovaleric acid moiety. The diols were principally branched chain C₂₁ and C₂₂ compounds while the long chain fatty acids esterified with them were mainly C₂₀ and C₂₁ branched compounds. The fatty acids from the sterol esters were mostly saturated, branched chain C₁₉ to C₂₃, together with 7% of straight chain monoenoic acids, principally C₂₁ and C₂₂. There were only trace amounts of free sterols other than cholesterol, while the esterified sterols contained 96% cholesterol and 4% lathosterol.     

Wax esters in the cystacanths ofPolymorphus minutus (Acanthocephala)

The lipids of the cystacanth of the acanthocephalanPolymorphus minutus have been analyzed. Wax esters constituted nearly 90% of the total cystacanth lipids. The wax ester fraction contained approximately 10% steroid ester; the rest was long chain alcohols C₁₂ to C₂₀, largely saturated, esterified with fatty acids C₁₂ to C₂₂, mostly unsaturated, with C₁₈ predominating. Corresponding quantities of wax esters were not found in the adult parasite. Cholesterol was identified as the only steroid present in the cystacanth.