Six new protoberberines were found in Stephama suberosa root extracts: (-)-tetrahydrostephabine, (-)-stephabinamine, stephabine, 8-oxypseudopalmatine, (-)-trans-xylopinine N-oxide and (-)-cis-xylopinine N-oxide. Ten known alkaloids were also detected: (-)-tetrahydropalmatine, (-)-tetrahydropalmatrubine, (-)-stepholidine, (-)-kikemanine, (-)-capaurimine, (-)-coreximine, (-)-corytenchine, (-)-discretine, pseudopalmatine and (-)-xylopinine. © 1987.