Homoisoflavonoids from Ophiopogon japonicus

Phytochemical study on the root tubers of Ophiopogon japonicus resulted in the isolation and identification of 13 homoisoflavonoids, including three new compounds, 8-formyl-7-hydroxy-5,4-dimethoxy-6-methylhomoisoflavone (1), 6-formylisoophiopogonone B (2), and 8-formylophiopogonanone B (4), and the ten known homoisoflavonoids 3, and 5-13. The absolute configurations of 8-formylophiopogonanone B (4) and 8-formyl-7-hydroxy-5,4-dimethoxy-6-methylhomoisoflavanone (5) were confirmed by time-dependent density-functional-theory (TD DFT) calculations of their theoretical electronic circular dichroism (ECD) spectra. The structure of the formerly reported 6-aldehydoisoophiopogonone B' was revised to 8-formylophiopogonone B (3). All compounds were evaluated for their cytotoxic activities against the human-lung-tumor A549 cell line, and compounds 3, 9, 10, and 13 exhibited promising antiproliferative activities with IC50 values of 10.01, 6.40, 0.84, and 1.66M, respectively.