The acylating residues were characterized as trans-cinnamic,n-decanoic, and either (þ)-(2S )-2-methylbutanoic or n-hexanoic acid. Purgin I (3) was found to be an ester-type dimer of operculinic acid A, acylated by n-dodecanoic, (þ)-(2S)-2-methylbutanoic, and trans-cinnamic acids at the same oligosaccharide core positions found incompounds 1 and 2. The site of lactonization by the aglycon in unit A was placed at C-2 of the second saccharide.