Yuyang Wu

Characterization of Plant Exudates by Principal-Component and Cluster Analyses with Nuclear Magnetic Resonance Variables

Principal-component and cluster analyses have been applied to nuclear magnetic resonance data for exudates derived from both conifers and angiosperms in order to classify these materials on the basis of molecular structure. The method succeeds in distinguishing resins produced by the conifer families Araucariaceae, Cupressaceae, and Pinaceae from each other and from resins produced by the angiosperm family Fabaceae. Other exudate types, including gums, gum resins, and kinos, also are distinguished from each other and from the resins.

Examination of amber and related materials by NMR spectroscopy

Examination of the solid‐state 13C and solution 1H NMR spectra of fossilized resins (ambers) has generated five groupings of materials based on spectral characteristics. The worldwide Group A is associated with the botanical family of the Araucariaceae. The worldwide Group B is associated with the Dipterocarpaceae. Baltic amber or succinite (Group C) is related to Group A but with a disputed conifer source. Amber from Latin America, the Caribbean, and Africa is associated with the Fabaceae, the genus Hymenaea in particular. The minor Group E contains the rare fossil polystyrene. The spectra of jet indicate that it is a coal‐like material with a rank between lignite and sub‐bituminous coal. Copyright

Characterization of Eucalyptus and Chemically Related Exudates by Nuclear Magnetic Resonance Spectroscopy

Exudates from six species of the genus Eucalyptus and one of the genus Corymbia (formerly Eucalyptus), from the family Myrtaceae, have been characterized by solid-state 13C and solution 1H NMR spectroscopy for the first time. Although these eucalypt kinos, as these exudates often are called, resemble resin (terpenoid) and gum (carbohydrate) exudates in physical appearance, their NMR spectra are dramatically different. In addition to lacking the characteristic terpene saturated resonances, they exhibit strong unsaturated resonances, which are weak for resins and absent for gums. We additionally report that exudates from genera of several other families of flowering plants (Amyris, Centrolobium, Guaiacum, Liquidambar, and Prosopis) also exhibit part or all of this kino spectroscopic signature.

Nuclear magnetic resonance spectroscopic characterization of legume exudates.

Exudates from the plant family Fabaceae have been characterized by proton and carbon-13 nuclear magnetic resonance spectroscopy. The 79 identified species from 38 genera represent all three subfamilies of this widespread and economically important angiospermous (flowering) family. The observed exudates include resins, gums, kinos, gum resins, and a few materials as yet unclassified molecularly. Exudates from the subfamily Caesalpinoideae are primarily resins, whereas those from the Mimoisoideae and Faboideae are primarily gums. Three species of the Mimoisoideae produce both gums and kinos.

Molecular classification of the natural exudates of the rosids

Exudates of the rosid clade of the eudicots have been surveyed and characterized by carbon-13 and proton nuclear magnetic resonance spectroscopy. Of 554 samples divided roughly equally between the subclades fabids and malvids, about two-fifths are resins, a third gums, one-ninth gum resins, one-twelfth kinos, and the remaining not affiliated with these four main molecular classes. Two small new molecular classes, respectively from the Clusiaceae (xanthics) and the Zygophyllaceae (guaiacs), are identified and described.

High-Resolution Solid State NMR Spectroscopy of Cultural Organic Material

Solid state NMR methods permit the examination of the bulk material of objects of importance to cultural heritage, without differential sampling characteristic of liquidand gas-phase techniques. Solid state C and H methods, primarily using magic angle spinning to enhance resolution and cross polarization (only with C) to enhance sensitivity (CP/MAS), permit analysis of organic components in a J.B. Lambert (*) Department of Chemistry, Trinity University, San Antonio, TX, USA e-mail: jlambert@trinity.edu Y. Wu Department of Chemistry, Northwestern University, Evanston, IL, USA e-mail: y-wu1@northwestern.edu J.A. Santiago-Blay Department of Paleobiology, National Museum of Natural History, Washington, DC, USA e-mail: blayj@si.edu # Springer International Publishing Switzerland 2016 G.A. Webb (ed.), Modern Magnetic Resonance, DOI 10.1007/978-3-319-28275-6_26-1 1 wide variety of historical and archaeological materials, including gemstones (amber, jet), wood, asphalt, food residues, rubber, lacquer, textiles, leather, parchment, paper, bone, and paintings. Heretofore the main drawback of the technique is that sample sizes are relatively large, 50–200 mg. Recent results, however, demonstrate that the use of a small sample chamber with very high spinning speeds can permit acquisition of data on <5 mg of sample.

Ferns, Cycads, Ginkgo, and Gnetophytes: Nuclear Magnetic Resonance Characterization of Exudates from Exotic Plant Sources

Rarely encountered exudates from the spore-bearing ferns and from the seedbearing living-fossil cycads, ginkgo, and gnetophytes have been examined in the bulk solid by carbon-13 nuclear magnetic resonance (NMR) spectroscopy and in some cases in solution with hydrogen NMR spectra. All 18 cycad samples proved to be gums, i.e., polycarbohydrates, as was one of the ferns. The two ginkgo samples and the other two ferns produced phenolic-based exudates. The single gnetophyte exudate was of an unknown and unique composition containing carbohydrate, saturated, and unsaturated components. None of the exudates proved to be resins (terpene-based materials), which are the most common molecular composition of exudates produced by conifers and flowering plants.