(±)-Quassidine K, a pair of cytotoxic bis--carboline alkaloid enantiomers from .

(±)-Quassidine K (), a pair of new bis--carboline alkaloid enantiomers, were isolated from . Their structures were determined on the basis of detailed spectroscopic data analysis. The absolute configurations of (+)--quassidine K () and (-)--quassidine K () were determined by comparing with the reported experimental ECD spectra after chiral separation.