Structural and In Vitro Biological Studies of Organotin(IV) Precursors; Selective Inhibitory Activity Against Human Breast Cancer Cells, Positive to Estrogen Receptors

Abstract

Crystals of Ph3SnCl (1) were grown from a methanol/acetonitrile solution. Compounds [Ph3SnOH]n (2) and [(Ph2Sn)4Cl2O2(OH)2] (3) were crystallized from diethyl ether/methanol/acetonitrile and hot acetone/water solutions respectively, of the white precipitation, formed by adding KOH to solutions of 1 and [Ph2SnCl2] in 1 : 1 and 1 : 2 molar ratios respectively. Complex 1 was characterized by X-ray crystallography. X-ray structure determination of compounds 2 and 3 confirmed the previously reported identities. The molecular structure of 1, reported here, is a new polymorphic form of the known one for Ph3SnCl. Four independent [Ph3SnCl] molecules constitute the crystal structure of 1. The moieties are packed in two pairs in a tail-to-tail arrangement. Complexes 1–3 were evaluated for their in vitro cytotoxic activity (cell viability) against human cancer cell lines: HeLa (human cervical), MCF-7 (breast, estrogen receptor (ER) positive), MDA-MB-231 (breast, ER negative), A549 (lung), Caki-1 (kidney carcinoma), 786-O (renal adenocarcinoma), K1 (thyroid carcinoma), and the normal human lung cell line MRC-5 (normal human fetal lung fibroblast cells) versus, the normal immortalized human mammary gland epithelial cell line MTSV17 with a sulforhodamine B (SRB) assay. The results show potent cytotoxic activity of the complexes against all cell lines used, which was superior to that of cisplatin (CDDP). Compounds 1–3 showed higher activity against breast cancer cells MCF-7 (ER positive) than against of MDA-MB-231 (ER negative). These findings prompted us to search for possible interaction of these complexes with other cellular elements of fundamental importance in cell proliferation. The influence of these complexes 1–3 upon the catalytic peroxidation of linoleic acid to hydroperoxylinoleic acid by the enzyme lipoxygenase (LOX), as well as their binding affinity towards calf thymus-DNA, were kinetically and theoretically studied.