Two novel insularine-N-oxides, insularine-2b-N-oxide (I) and insularine-2'b-N-oxide (II), were isolated along with insularine and insulanoline from the roots of C. sutchuenensis indigenous only to China. Their structures have been elucidated on the basis of spectral anal. and confirmed by chem. correlation with insularine. Both I and II are rare examples of naturally occurring head-to-tail bisbenzylisoquinoline N-oxides. Additional, the 1H and 13C NMR spectral data of insulanoline were first reported and assigned in detail. Insulanoline showed significant inhibitory activity against human colon adenocarcinoma.

Key words: SEPARATION, C13 NMR SPECTROMETRY, BISBENZYL ISOQUINOLINE ALKALOID, PROTON MAGNETIC RESONANCE SPECTROMETRY, ANTINEOPLASTIC ACTIVITY