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The isolation and characterization of 19 new alkaloids from the bark of Galbulimima species is described. After some corrections to previous work, the number of alkaloids from this source now stands at 28.

The structure (III) proposed for the hexacyclic alkaloid, himgaline, on the basis of chemical and spectroscopic characterization was confirmed by several partial syntheses of himgaline derivatives from de-N-methylhimbadine (alkaloid G.B. 13). The biogenesis of the Galbulimima alkaloids is discussed.

The structures of himbadine (I) and its de-N-methyl derivative (II), alkaloid G.B. 13, proposed on the basis of chemical and spectroscopic characterization were confirmed by several partial syntheses from the ester alkaloid, himandrine (III), of known structure.