FIGURE 3.

Structure elucidation of sevanol as epiphyllic acid 9,10-diisocitryl ester. A, proposed structure of sevanol with numbering of carbon atoms. B, observed positive ROESY (wavy lines) and ¹H → ¹³C HMBC connectivities (bold lines for strong peaks and thin lines for weak peaks in the HMBC NMR spectrum). C, observed fragmentation of sevanol in the LC-ESI⁺ mass spectrum. Fragments 295, 469, and 497 are speculated to be due to the formation of a double bond between atoms 1 and 2 followed by the release of one water molecule with the participation of an ester oxygen atom.