Merrekentrones A-D, ipomeamarone-like furanosesquiterpenes from Merremia kentrocaulos

Four new furanosesquiterpenes, merrekentrones A (1), B (2), C (3), and D (4 ), were isolated from the roots and rootstocks of Merremia kentrocaulos. Th eir structures were elucidated on the basis of spectroscopic data interpret ation. In contrast to ipomeamarone (5), the well-known phytoalexin of Ipomo ea batatas, 1-4 seem to be normal plant constituents, Merrekentrone A (1) w as also detected in the roots of M. guerrichii and M. aurea.