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Plamen Mitov - One of the best experts on this subject based on the ideXlab platform.
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Chemical Ecology of Cave-Dwelling Millipedes: Defensive Secretions of the Typhloiulini (Diplopoda, Julida, Julidae)
Journal of Chemical Ecology, 2017Co-Authors: Slobodan E. Makarov, Michaela Bodner, Boyan Vagalinski, Dragan Ž. Antić, Ljubodrag V. Vujisić, Doris Reineke, Marina M. Todosijević, Luka R. Lučić, Bojan M. Mitić, Plamen MitovAbstract:Cave animals live under highly constant ecological conditions and in permanent darkness, and many evolutionary adaptations of cave-dwellers have been triggered by their specific environment. A similar “cave effect” leading to pronounced chemical interactions under such conditions may be assumed, but the chemoecology of troglobionts is mostly unknown. We investigated the defensive chemistry of a largely cave-dwelling julid group, the controversial tribe “Typhloiulini”, and we included some cave-dwelling and some endogean representatives. While chemical defense in juliform diplopods is known to be highly uniform, and mainly based on methyl- and methoxy-substituted Benzoquinones, the defensive secretions of typhloiulines contained ethyl-Benzoquinones and related compounds. Interestingly, ethyl-Benzoquinones were found in some, but not all cave-dwelling typhloiulines, and some non-cave dwellers also contained these compounds. On the other hand, ethyl-Benzoquinones were not detected in troglobiont nor in endogean typhloiuline outgroups. In order to explain the taxonomic pattern of ethyl-Benzoquinone occurrence, and to unravel whether a cave-effect triggered ethyl-Benzoquinone evolution, we classed the “Typhloiulini” investigated here within a phylogenetic framework of julid taxa, and traced the evolutionary history of ethyl-Benzoquinones in typhloiulines in relation to cave-dwelling. The results indicated a cave-independent evolution of ethyl-substituted Benzoquinones, indicating the absence of a “cave effect” on the secretions of troglobiont Typhloiulini. Ethyl-Benzoquinones probably evolved early in an epi- or endogean ancestor of a clade including several, but not all Typhloiulus (basically comprising a taxonomic entity known as “ Typhloiulus sensu stricto”) and Serboiulus . Ethyl-Benzoquinones are proposed as novel and valuable chemical characters for julid systematics.
Slobodan E. Makarov - One of the best experts on this subject based on the ideXlab platform.
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Chemical Ecology of Cave-Dwelling Millipedes: Defensive Secretions of the Typhloiulini (Diplopoda, Julida, Julidae)
Journal of Chemical Ecology, 2017Co-Authors: Slobodan E. Makarov, Michaela Bodner, Boyan Vagalinski, Dragan Ž. Antić, Ljubodrag V. Vujisić, Doris Reineke, Marina M. Todosijević, Luka R. Lučić, Bojan M. Mitić, Plamen MitovAbstract:Cave animals live under highly constant ecological conditions and in permanent darkness, and many evolutionary adaptations of cave-dwellers have been triggered by their specific environment. A similar “cave effect” leading to pronounced chemical interactions under such conditions may be assumed, but the chemoecology of troglobionts is mostly unknown. We investigated the defensive chemistry of a largely cave-dwelling julid group, the controversial tribe “Typhloiulini”, and we included some cave-dwelling and some endogean representatives. While chemical defense in juliform diplopods is known to be highly uniform, and mainly based on methyl- and methoxy-substituted Benzoquinones, the defensive secretions of typhloiulines contained ethyl-Benzoquinones and related compounds. Interestingly, ethyl-Benzoquinones were found in some, but not all cave-dwelling typhloiulines, and some non-cave dwellers also contained these compounds. On the other hand, ethyl-Benzoquinones were not detected in troglobiont nor in endogean typhloiuline outgroups. In order to explain the taxonomic pattern of ethyl-Benzoquinone occurrence, and to unravel whether a cave-effect triggered ethyl-Benzoquinone evolution, we classed the “Typhloiulini” investigated here within a phylogenetic framework of julid taxa, and traced the evolutionary history of ethyl-Benzoquinones in typhloiulines in relation to cave-dwelling. The results indicated a cave-independent evolution of ethyl-substituted Benzoquinones, indicating the absence of a “cave effect” on the secretions of troglobiont Typhloiulini. Ethyl-Benzoquinones probably evolved early in an epi- or endogean ancestor of a clade including several, but not all Typhloiulus (basically comprising a taxonomic entity known as “ Typhloiulus sensu stricto”) and Serboiulus . Ethyl-Benzoquinones are proposed as novel and valuable chemical characters for julid systematics.
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chemical defense in millipedes myriapoda diplopoda do representatives of the family blaniulidae belong to the quinone clade
Chemistry & Biodiversity, 2014Co-Authors: Ljubodrag Vujisic, Dragan ž Antic, Ivan Vuckovic, Tatjana Lj Sekulic, V T Tomic, Boris Mandic, Vele Tesevic, Božidar P M Curcic, V Vajs, Slobodan E. MakarovAbstract:The defensive secretions of two blaniulid millipedes, Nopoiulus kochii and Cibiniulus phlepsii, were characterized by GC-FID and GC/MS analyses, which showed the presence of a complex mixture of Benzoquinones, hydroquinones, and oleates. Altogether, 13 compounds were identified. The major compound in the secretions of both analyzed species was 2-methyl-1,4-Benzoquinone (toluquinone). The second major constituent in the N. kochii secretion was 2-methyl-3,4-(methylenedioxy)phenol, while in that of C. phlepsii, it was 2-methoxy-3-methyl-1,4-Benzoquinone. The defensive secretion of N. kochii also showed a high content of hydroquinones (13.5%) in comparison to that of C. phlepsii (0.8%). Hexyl oleate and octyl oleate were detected for the first time in defensive millipede fluids. The chemical composition of the defensive secretions supports the chemotaxonomic position of the family Blaniulidae in the ‘quinone’ millipede clade.
Peter Langer - One of the best experts on this subject based on the ideXlab platform.
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synthesis of tetraaryl p Benzoquinones and 2 3 diaryl 1 4 naphthoquinones via suzuki miyaura cross coupling reactions
Tetrahedron, 2013Co-Authors: Zahid Hassan, Ihsan Ullah, Rasheed Ahmad Khera, Alexander Villinger, Ingo Knepper, Tamas Patonay, Peter LangerAbstract:The palladium-catalyzed Suzuki–Miyaura coupling reaction of tetrabromo-p-Benzoquinone and 2,3-dibromonaphthoquinone provide a convenient approach to tetraaryl-p-Benzoquinones and 2,3-diarylnaphthoquinones. Suzuki–Miyaura of tetrabromo-1,4-phenylene bis(trifluoromethanesulfonate) and of 2,3-dibromonaphthalene-1,4-diyl bis(trifluoromethanesulfonate) resulted in the formation of the same type of quinone products instead of the expected benzene and naphthalene derivatives.
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synthesis of tetraaryl p Benzoquinones by suzuki miyaura cross coupling reactions of tetrabromo p Benzoquinone
Tetrahedron Letters, 2009Co-Authors: Ihsan Ullah, Rasheed Ahmad Khera, Munawar Hussain, Alexander Villinger, Peter LangerAbstract:Abstract Suzuki–Miyaura cross-coupling reactions of tetrabromo- p -Benzoquinone provide a convenient approach to tetraaryl- p -Benzoquinones.
Sergiy V Rosokha - One of the best experts on this subject based on the ideXlab platform.
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intermolecular interactions between halogen substituted p Benzoquinones and halide anions anion π complexes versus halogen bonding
ChemPlusChem, 2020Co-Authors: Almaz S Jalilov, Matthias Zeller, Spencer Deats, Muath Albukhari, Sergiy V RosokhaAbstract:Intermolecular interactions between halo-substituted p-Benzoquinones (BQ) and halide anions were examined in solution, solid-state and/or in silico. While X-ray crystallography revealed only halogen bonding (XB) between tetraiodo-p-Benzoquinone (I4 Q) and halides, the results of a UV-Vis study in solutions were consistent with the formation of 1 : 1 anion-π complexes. DFT computations showed that the anion-π complexes of halides with most halo-substituted BQ molecules were more stable (by 2-7 kcal/mol) than their XB analogues, but the stabilities of different complexes of I4 Q were essentially the same. Thus, the structural features of the co-crystals with I4 Q were related to multicenter XB interactions between BQs and halides, thus leading to the formation of 3D networks. The observation of anion-π complexes in solutions was attributed to their higher molar absorptivity (by more than an order of magnitude) than that of their XB analogues. Overall, the stabilities of anion-π and XB complexes between BQs and halides were well correlated with the values of highest electrostatic potentials on the surfaces of BQ molecules when their polarizations were taken into account.
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anion π complexes of halides with p Benzoquinones structures thermodynamics and criteria of charge transfer to electron transfer transition
Journal of the American Chemical Society, 2019Co-Authors: Slade Kepler, Matthias Zeller, Sergiy V RosokhaAbstract:Interchange of complex formation and electron-transfer reactions between halide anions and p-Benzoquinones were established via UV–vis spectral and X-ray structural measurements and computational analysis. Solution-phase interaction of the p-Benzoquinone acceptors with Cl–, Br–, or I– donors led to the formation of anion−π complexes showing strong absorption bands in the UV–vis range. Formation constants and calculated interaction energies of these complexes increased, and donor/acceptor separations decreased with increasing reduction potentials of p-Benzoquinones. Mulliken correlation and NBO analysis indicated a charge-transfer nature of these anion−π associates. Most notably, the increase of the acceptor strength led to a transition between the formation of the persistent anion−π complexes and electron-transfer reactions. Thermodynamic analysis accounted for the experimental observations of anion radicals and trihalide anions in solutions of p-Benzoquinones with iodide or (for the strongest acceptor) b...
Anita J. Marsaioli - One of the best experts on this subject based on the ideXlab platform.
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Chemical Defense in Harvestmen (Arachnida, Opiliones): Do Benzoquinone Secretions Deter Invertebrate and Vertebrate Predators?
Journal of Chemical Ecology, 2005Co-Authors: Glauco Machado, Patricia C. Carrera, Armando M. Pomini, Anita J. MarsaioliAbstract: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.