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  • 1
    ISSN: 1573-1561
    Keywords: Alkaloids ; mass spectrometry ; infrared spectroscopy ; amphibians ; ants ; decahydroquinolines ; quinolizidines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Three alkaloids—two minor decahydroquinolines (DHQs) and a major quinolizidine—were detected in an extract of a Brazilian myrmicine ant (Solenopsis (Diplorhoptrum) sp. picea group). One DHQ (3) was identical to a known frog-skin alkaloid, cis-195A (cis-5-methyl-2-propyldecahydroquinoline), while the second DHQ, an isomer of 3, designated 195J, was assigned a tentative cis-2-methyl-5-propyldecahydroquinoline structure (2) based on mass and infrared spectra. The third alkaloid proved identical to the frog-skin alkaloid 195C, for which a structure had not been previously proposed. Mass and infrared spectral analysis, including chemical ionization tandem mass spectrometry, indicated a 4-methyl-6-propylquinolizidine structure (1) for 195C. The four possible diastereomers were synthesized and the (6Z,10E)-4-methyl-6-propylquinolizidine diastereomer (1b) was identical to the natural alkaloid. Skin extracts of a population of a Madagascan mantelline frog contained, among other alkaloids, minor amounts of the same alkaloid triad 1–3 with 1 again predominating. The common occurrence of alkaloids 1–3 in both ant and frog supports the hypothesis that ants are a likely dietary source for sequestered frog-skin alkaloids and brings to six, the alkaloid classes common to ant and frog.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-1561
    Keywords: Alkaloids ; coccinellines ; decahydroquinolines ; indolizidines ; pyrrolidines ; pyrrolizidines ; dendrobatid frogs ; myrmicine ants ; coccinellid beetles ; millipedes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Neotropical poison frogs (Dendrobatidae) contain a wide variety of lipophilic alkaloids, apparently accumulated unchanged into skin glands from dietary sources. Panamanian poison frogs (Dendrobates auratus) raised in a large, screened, outdoor cage and provided for six months with leaf-litter from the frog's natural habitat, accumulated a variety of alkaloids into the skin. These included two isomers of the ant pyrrolizidine 251K; two isomers of the 3,5-disubstituted indolizidine 195B; an alkaloid known to occur in myrmicine ants; another such indolizidine, 211E; two pyrrolidines, 197B and 223N, the former known to occur in myrmicine ants; two tricyclics, 193C and 219I, the former known to occur as precoccinelline in coccinellid beetles; and three spiropyrrolizidines, 222, 236, and 252A, representatives of an alkaloid class known to occur in millipedes. The alkaloids 211E, 197B, and 223N appear likely to derive in part from ants that entered the screened cage. In addition, the frog skin extracts contained trace amounts of four alkaloids, 205D, 207H, 219H, and 231H, of unknown structures and source. Wild-caught frogs from the leaf-litter site contained nearly 40 alkaloids, including most of the above alkaloids. Pumiliotoxins and histrionicotoxins were major alkaloids in wild-caught frogs, but were absent in captive-raised frogs. Ants microsympatric with the poison frog at the leaf-litter site and at an island site nearby in the Bay of Panamá were examined for alkaloids. The decahydroquinoline (−)-cis-195A and two isomers of the pyrrolizidine 251K were found to be shared by microsympatric myrmicine ants and poison frogs. The proportions of the two isomers of 251K were the same in ant and frog.
    Type of Medium: Electronic Resource
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