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Louw S.,Laboratory for Ecological Chemistry | Burger B.V.,Laboratory for Ecological Chemistry | Le Roux M.,Laboratory for Ecological Chemistry | Le Roux M.,Stellenbosch University | Van Wyk J.H.,Laboratory for Ecological Chemistry
Journal of Natural Products | Year: 2011

In lizards, the epidermal glands of the femoral and precloacal regions are involved in the production of semiochemicals. In addition to its femoral glands, the giant girdled lizard, or sungazer, Cordylus giganteus, which is endemic to South Africa, has generation glands as an additional potential source of semiochemicals. These epidermal glands are described as glandular scales that overlay the femoral glands and are included in the normal epidermal profile located in the femoral (thigh) and anterior antebrachial (fore-leg) regions of the male sungazer. GC-MS analysis of the generation gland secretions and the trimethylsilyl derivatives of some of the steroidal constituents was employed to identify 59 constituents, including alkenes, carboxylic acids, alcohols, ketones, aldehydes, esters, amides, nitriles, and steroids. The quantitative differences of the volatile constituents of the fore- and hind-leg generation glands were compared between individuals. This is the first report on the chemical composition of generation glandular material of lizards. © 2011 The American Chemical Society and American Society of Pharmacognosy.

Catallo W.J.,Laboratory for Ecological Chemistry | Shupe T.F.,Louisiana State University | Comeaux J.L.,Mcneese State University | Junk T.,University of Louisiana at Monroe
Biomass and Bioenergy | Year: 2010

This work examined the transformation of glucose in hydrothermal (HT) reaction systems. Isotopic studies and comparative product analysis were used to gain insight on the most prevalent HT reactions. HT in H2O16 and H2O18 showed that transformation of glucose to gaseous and semi-volatile compound mixtures was dominated by hydration/oxidation reactions by water molecules in the reaction medium. Dissolved molecular oxygen and oxygen from the substrate were minimally involved in the observed oxidation reactions. HT of glucose in D2O indicated that most of the hydrocarbons, phenolics, and related reduced compounds in the products were from reactions involving unsaturated fragments of the substrate molecules. Except for furans and alkyl furans, there was no evidence of reduction and aromatization reactions acting directly on glucose rings: these molecules first underwent fragmentation and desaturation reactions prior to the formation of semi-volatile products. These reactive fragments underwent further reactions to form semi-volatile products such as Diels-Alder additions. Timed-release of NaBH4 to the HT system decreased the relative amount of CO2 generated and increased the yields of hydrocarbon products. This indicated that levels of reducing hydrogen species limit the yields of reduced products such as hydrocarbons and allow hydration/oxidation reactions to "steal" substrate carbon atoms and generate oxidized products, notably CO2. Co-reactants entering the HT reaction mixture as a result of containerization (e.g., Ni) also influenced the products of HT reaction. The presence of leached reactor metals in the medium was found to affect both quantities and types of compounds found in both the volatile and semi-volatile phases. © 2009.

PubMed | Laboratory for Ecological Chemistry
Type: Journal Article | Journal: Journal of chemical ecology | Year: 2013

Using gas chromatography-mass spectrometry 33 constituents of the preorbital gland of the grey duiker,Sylvicapra grimmia, were identified as unbranched alkanes, 2-alkanones, alkanals, alkanoic acids, alkan-4-olides, as well as 3-methyl-3-buten-1-ol, (Z)-9-octadecenoic acid, benzyl cyanide, diethyl sulfoxide, 2-isobutyl-1,3-thiazole, 2-isobutyl-4,5-dihydro-1,3-thiazole, and 3,4-epoxy-2-dodecanone. Determination of the relative concentrations of these components in a limited number of secretion samples taken from males and females revealed that in these samples the two thiazole derivatives and the epoxy ketone were present in consistently and significantly higher concentrations in male than in female secretions. This suggests that they could act as sex recognition cues.

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