Synthesis And Structure-Activity Relationship Of Lipo-Diterpenoid Alkaloids With Potential Target Of Topoisomerase Ii Alpha For Breast Cancer Treatment

Aconitine linoleate (11) isolated from the Aconitum sinchiangense W. T. Wang exhibited significant anti-tumor activity. Based on this, a series of novel lipo-diterpenoid alkaloids were synthesized and evaluated for their anticancer activities against MCF-7 and MCF-7/ADR cell lines. Seventeen compounds, including 18-20, 22, 24-32, 36, 39, 41-42 possessed higher anti-proliferative activities (IC50 < 20 mu M) against MCF-7 cell lines, which were better than the reference drug etoposide (IC50 = 18.01 +/- 1.64 mu M), among which compound 24 (IC50 = 4.00 +/- 0.30 mu M) was found to be the most potent derivative, being 4.5-fold more active than etoposide. Meanwhile, eighteen compounds, including 18-22, 24, 26-32, 36, 38-39, 41-42 presented excellent activities (IC50 < 20 mu M) against MCF-7/ADR cell lines, better than etoposide (IC50 = 35.48 +/- 0.29 mu M) and doxorubicin (IC50 = 67.61 +/- 6.5 mu M). The most potent compound (19) was 13.5- and 25.7-fold more active than etoposide and doxorubicin against MCF-7/ADR cell lines, respectively. The structure-activity relationship (SAR) studies indicated that the 3-OH, 8-lipo, 14-benzene ring, and nitrogen atom with proper alkaline are crucial elements for anti-proliferative activity of target lipo-diterpenoid compounds. The proper length, the double bonds or difluoro-substituted at C-8 fatty acid chain, the para-donating electron group on 14-benzene group, and 13-OH are all favorable for the enhancement of anti-proliferative activities. In conclusion, the introduction of the 8-lipo group into aconitine leads to significant increase of anti-proliferative activity against MCF-7 and MCF-7/ADR cells, which suggests these kinds of lipo-alkaloids are powerful and promising antitumor compounds for breast cancer, especially for drug-resistant breast cancer.