Stems of Coscinium fenestratum from Thailand furnished the new protoberberine alkaloids oxypalmatine, (-)-8- oxotetrahydrothalifendine, (-)-8-oxoisocorypalmine and either (-)-8-oxothaicanine or (-)-8-oxo-3-hydroxy-2,4, 9,10-tetramethoxyberbine in addition to berberine, the major alkaloid and (-)-8-oxocanadine. © 1992.