Bipleiophylline, an unprecedented cytotoxic bisindole alkaloid constituted from the bridging of two indole moieties by an aromatic spacer unit

A cytotoxic bisindole alkaloid possessing an unprecedented structure in which two indole moieties are bridged by an aromatic spacer unit has been isolated from Alstonia angustifolia. The structure was established by analysis of the spectroscopic data and confirmed by X-ray diffraction analysis. A possible biogenetic pathway from pyrocatechuic acid and pleiocarpamine is presented.