Synthesis and cytotoxicity of a novel iridoid glucoside derived from aucubin.

The novel iridoid glycoside 2 was prepared in six steps (15% overall yield) from natural aucubin (1) and fully characterized. Compound 2, which comprises the same conjugated cyclopentenone pharmacophore as known antitumor oxylipins and prostaglandins, displayed significant antiproliferative in vitro activity towards leukemia L1210 cells. The Michael addition of nucleophilic thiols to compound 2 occurred on a different position compared to classical delta7-prostaglandin A1 methyl ester. The resulting adducts 7a and 7b were fully characterized, and their MS fragmentation patterns were elucidated.