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Three alkaloids, acosmine 1, acosmine acetate 2 and panacosmine 3 with a n~wel diaza- adamantane skeleton and an unusual N-acetyl enamine moiety, have been i.~lated from the :'seeds of Acosmium panamense (Benth.). The structures were a~embled on the basis of COSY, HMQC and HMBC data with the assistance of the LSD structure elucidation Ix'ogram. Proton-nitrogen HMBC experiments supl~rt the ~ structures. Other isolated compounds include 4ot-angeloyloxy-31~- hydroxy-131~-methoxylupanine 4, a new compound, and the known alkaloids lupanine and multiflorine. © 1999 Elsevier Science Ltd. All rights reserved. Acosmium panamense (Benth.) Yakovlev (Fabaceae) 1, known as Sweetia panamense 2, is a tall tree originating in central America, li'om Mexico to Venezuela. In central America, the bitter bark has been used in traditional medicine as a remedy for diseases such as syphilis and malaria 3. The hard wood of A. panamense is used as building material. A. panamense was introduced into Ali'ica in the Congo (Kinshasa) under the erroneous name A. brachystachya 4. Chemical investigation of the root bark resulted in the isolation of the alkaloids sweetenine ~ and 4~-hydroxysparteine 5. More recently methoxylated quinolizidine alkaloids have been described 6. This article describes the results of a chemical investigation of the seeds of A. panamense. The ground seeds ofA. panamense were first defatted and then submitted to alkaloid .separation by means of acid-base extraction 7. Purification of the alkaloid mixtures by column chromatography on silica gel led to the isolation of six compounds. The known alkaloids lupanine and multiflorine were identified by comparison of their spectra with literature data s. The structure elucidation of the lbur new compounds is described below. The El mass spectrum of acosmine 1 reveals an (MI + ion at mlz 359. The regular and J-modulated 13C NMR spectra show 21 carbons (I methyl, 10 methylenes, 8 methines and 2 non-protonated carbons) bearing a total of 31 hydrogen atoms. A proton at 5 7.4 ppm (NH) is not bound to a carbon atom as indicated by the ~H-~3C HSQC spectrum. The odd mass of the molecular ion imposes an odd number of hydrogen and nitrogen |
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