Discovery of Novel Bioactive Tanshinones and Carnosol Analogues against Breast Cancer.

The abietane diterpenoids ferruginol ( 1 ), tanshinone IIA ( 3 ), and carnosol ( 4 ) are well-known for their interesting pharmacological properties, including antitumor, similar to other natural and semisynthetic abietanes. In this study, a pair of semisynthetic C18-functionalized analogues of 3 and 4 were prepared from the commercially available (+)-dehydroabietylamine or readily obtained methyl dehydroabietate. Semisynthetic ferruginol ( 1 ) and some selected analogues, together with the synthesized analogues, were tested in vitro for the inhibition of proliferation in four breast cancer cell lines, SUM149, MDA-MB231, T47D, and MCF07. As a result, several tested abietane analogues decreased cell proliferation and enhanced cell death, with IC 50 in the range 1.3-18.7 μM. This work demonstrates the antitumor activities of two tested compounds, making these molecules interesting for the development of new anticancer agents.