On the Alkaloids of Aconitum japonicum THUNB. collected at Mt. Takao (Tokyo)

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Abstract
Reinvestigation of the alkaloids of A. japonicum Thunb. of Mt. Takao (Tokyo) was made. In addition to the reported constituents, i.e., isohypognavine, delcosine and dehydrodelcosine, 2 known compounds, isotalatisidine and condelphine, were isolated. Furthermore, 5 new bases, i.e., 11-acetylisohypognavine, diacetylisohypognavine, 14-acetyltalatisamine, takaosamine and takaonine, were isolated and their structures were elucidated. Takaosamine was 18-0-demethyldelcosine from the spectroscopic study on the parent material and the acetyl derivatives, and from the chemical correlation with known diterpene alkaloids, gigactonine and delsoline. The structure of takaonine was deduced to be 2,3-dehydro-14-dehydrodelcosine on the basis of 13C-NMR spectral evidence and the derivation to the known diterpene alkaloid, delcosine, by catalytic hydrogenation.