Two new maytansinoids from maytenus buchananii

Reinvestigation of fractions derived from large-scale fractionation of Maytenus buchananii led to the isolation of two new maytansinoids. The structures of these principles were determined using electrospray MS, 1H NMR, 13C NMR, and 2D NMR techniques. One principle was found to be 2'-N-demethylmaytanbutine (2), while the other was found to be maytanbicyclinol (3), the first maytansinoid with two macrocyclic rings to be isolated from a Maytenus species.