Structures and allelopathic effects ofNuphar alkaloids: Nupharolutine and 6,6'-dihydroxythiobinupharidine.

Two of the majorNuphar alkaloids, nupharolutine and 6,6'-dihydroxythiobinupharidine, were isolated from the aquatic perennial herbNuphar lutea (L.) Sibth. & Sm., yellow water lily. In a lettuce seedling bioassay of the two pure compounds, the former was inactive and the latter was highly inhibitory of radicle elongation at concentrations greater than 2 ppm. Structures and stereochemistry of the two compounds were confirmed by DEPT,(1)H-(1)H COSY,(1)H-(13)C COSY, and(1)H-(1)H NOESY experiments.