A new promorphinane alkaloid (-)-8,14-dihydroflavinantine was isolated from the aerial parts of Papaver nudicaule L. (Papaveraceae) growing in Mongolia. Six known isoquinoline alkaloids (+)-amuronine, pseudoprotopine, allocryptopine, (-)-dihydroamuronine, (-)-amurensinine N-oxide A and (-)-amurensinine N-oxide B were isolated, too. Pseudoprotopine has been found for the first time in a plant of the family Papaveraceae. (-)-dihydroamuronine, (-)-amurensinine N-oxide A and (-)-amurensinine N-oxide B are new for the genus Papaver. All structures were established using spectral and physical data.

A racem. 8,14-dihydroamurine is a new promorphinane alkaloid isolated from the aerial parts of Papaver nudicaule L. (Papaveraceae) of Mongolian origin. The known promorphinane and isopavine alkaloids (+)-amurine, (-)-amurensinine, (-)-O-methylthalisopavine, (-)-flavinantine and (-)-amurensine were also described. All structures were established by physical and spectral analysis. Flavinantine has been found for the first time in the species.