New ferrocene modified lawsone Mannich bases with anti-proliferative activity against tumor cells

Lawsone (1a) is a known naphthoquinone dye from the Henna plant Lawsonia inermis. Out of a series of four new ferrocene modified Mannich bases of 1a, the 2-pyridyl derivative 2a was distinctly more active than its analogs 2b-d in breast, prostate and pancreatic cancer cells. 2a also exhibited greater antiproliferative effects when compared with the known anticancer active Mannich bases 1b and 1c in the androgen-receptor negative PC-3 prostate and Pgp-expressing KB-V1/Vbl cervix carcinoma cell lines. Compound 2a reached sub-micromolar activities in these aggressive cancer cells and, thus, features a promising drug candidate for the efficient treatment of hormone- or multidrug-resistant cancer types.