Bolivianine, a new sesterpene with an unusual skeleton from Hedyosmum angustifolium, and its isomer, isobolivianine.

Bolivianine, a novel sesterpene with an unprecedented skeleton, has been isolated from the trunk bark of Hedyosmum angustifolium (Chloranthaceae), with isobolivianine, an isomer formed under acidic conditions. The structure and relative stereochemistry were elucidated on the basis of spectroscopic data. A hypothesis for biogenesis was made.