corresponding to the molecular formula C144H232O52 for the natural product. A high-mass fragment ion [M/2H]
resulting from the ester-type dimer cleavage 12,14 was observed at m/z1395.7767 in addition to its corresponding chlorine adduct at m/z1431.7543. Other peaks produced by cleavage of the lipophilic esters as well as the glycosidic linkages were similar to those observed for purginoside I (1), confirming the branched pentasaccharide core as operculinic acid A for both units A and B in the structure of compound 3. Accordingly, the general structure for compound 1 was used as the starting point for the characterization of each unit forming the ester-type dimer in3. The difference of 182 mass units between the peaks at m/z1265 [M/2H130 (C9H6O)] and 1083 [M/2H130 (C9H6O)182 (C12H22O)] suggested
the loss of a dodecanoyl residue instead of a decanoyl ester as observed for compound 1