N-methyldecahydroquinolines: an unexpected class of alkaloids from Amazonian poison frogs (Dendrobatidae).
The dominant alkaloids previously identified in skin extracts of Amazonian dendrobatid frogs of the genus Ameerega are histrionicotoxins and 2,5-disubstituted decahydroquinolines. Analysis of alkaloids in skin extracts of Ameerega picta from Bolivia revealed that the alkaloid 257A, previously reported as a 2,5-disubstituted decahydroquinoline, is an N-methyl-2,5-disubstituted decahydroquinoline. We characterized alkaloids of another 12 of the more than 25 species recently assigned to the genus Ameerega, and five additional N-methyldecahydroquinolines were identified. In some cases, the relative configuration of the N-methyldecahydroquinolines was determined by comparison with the N-methylated products prepared from the corresponding 2,5-disubstituted decahydroquinolines of known relative configuration. A dietary source for N-methyldecahydroquinolines is unknown; however, myrmicine ants are the likely source for the 2,5-disubstituted decahydroquinolines. The alkaloids in skin extracts of three species of another genus of Amazonian poison frog, Adelphobates, were also characterized, but N-methyldecahydroquinolines were not detected.
Daly
John W
JW
Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, DHHS, Bethesda, Maryland 20892-0820, USA.
Ware
Nathaniel
N
Saporito
Ralph A
RA
Spande
Thomas F
TF
Garraffo
H Martin
HM
D000470:Alkaloids / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D000664:Amphibian Venoms / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D000818:Animals; D001001:Anura / Q000235:genetics / Q000502:physiology*; D001838:Bolivia; D015394:Molecular Structure; D011804:Quinolines / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D012867:Skin / Q000737:chemistry / Q000378:metabolism
D000470:Alkaloids; D000664:Amphibian Venoms; D011804:Quinolines