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 C-13 and solution H-1 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.