(+)/(-)-Yanhusuosines A and B, two dimeric benzylisoquinoline-protoberberine alkaloid atropo-enantiomers featuring polycyclic skeletons from Corydalis yanhusuo

(+)/(-)-Yanhusuosines A(1) and B(2), two pairs of trace benzylisoquinoline-protoberberine atropoenantiomeric homodimers featuring an unprecedented 6/7/6/6/6/6 hexacyclic skeleton, were isolated from the tubers of Corydalis yanhusuo. The structures of(+)/(-)-1 and(+)/(-)-2 were elucidated using spectroscopic and quantum-chemical calculation approaches.(+)/(-)-Yanhusuosines A(1) and B(2)represent a new class of alkaloid dimers biogenetically constructed by a molecule of benzylisoquinoline with a unit of protoberberine via an intermolecular [4 + 3] cycloaddition. Their plausible biosynthetic pathways are discussed, and compound 2 exerted moderate inhibitory activity of NO formation in LPS induced RAW264.7 macrophages.