ANTITUMOR AGENTS .157. ABSOLUTE STRUCTURES OF CUMINGIANOSIDES A-F, ANTILEUKEMIC TRITERPENE GLUCOSIDES, AND STRUCTURES OF THE HYDROLYSATES OF CUMINGIANOSIDE-A

The Stereostructures of cumingianosides A-F, a series of triterpene gl ucosides with a 14,18-cycloapoeuphane skeleton, have been established by X-ray crystallographic analysis on an aglycone [1c] the acid hydrol ysate of cumingianoside A [1], which is a potent cytotoxic triterpene against MOLT-4 human leukemia cells with an EC(50) value of <0.00625 m u M. The 14,18-cyclopropane ring in cumingianoside A [1] was opened un der acidic conditions in two different directions to give compounds wi th an apoeuphane skeleton and a dammarane skeleton. Furthermore, it wa s found that subsequent hydrolysis yielded not only an aglycone with a n apoeuphane skeleton [1c] but also an apo-rearrangement product [1d].