Study of the anticancer properties of methyl- and phenyl-substituted carbon- and silicon-bridged ansa-titanocene complexes

Abstract

The previously known complexes {[}Ti\{(Me2CMe2C)(eta(5)-C5H4)(2)\}Cl-2] (1), {[}Ti\{Me2C(eta(5)-C5H4)(2)\}Cl-2] (2), {[}Ti \{Me2Si(eta(5)-C5H4)(2)\}Cl-2] (4), {[}Ti\{MePhSi(eta(5)-C5H4)(2)\}Cl-2] (5) and {[}Ti\{MePhSi(eta(5)-C5Me4)(2)\}Cl-2] (6) have been prepared following reported procedures. The novel complex {[}Ti\{MePhC(eta(5)-C5H4)(2)\}Cl-2] (3) has been prepared and characterized. The cytotoxic activity of 1-6 has been tested after 72 h on melanoma A375 and B16, prostate cancer DU145 and LNCaP and colon cancer HCT116, SW620 and CT26CL25 cell lines observing a high cytotoxic activity of complexes 1 and 6 compared to the reference compound ({[}Ti(eta(5)-C5H5)(2)\}Cl-2]). 1 and 6 have also been tested against primary normal mouse keratinocytes and lung fibroblasts. While viability of both type of primary cells was significantly less affected by 1 in comparison to the reference compound {[}Ti(eta(5)-C5H5)(2)Cl-2], compound 6 was completely nontoxic for nonmalignant cells, indicating a potential selectivity of this compound towards cancer cell lines. In addition CFSE staining, cell cycle analysis, AnnexinV-FITC/PI staining, detection of caspase activity and mitochondrial potential showed that 1 and 6 were acting through inhibition of proliferation and subsequent induction of mitochondrial dependent apoptosis in colon cancer cell lines, HCT116 and SW620, which express low sensitivity to cisplatin. Compound 6 was found to be the leading drug in this group since it shows the fastest and most selective anticancer profile. (C) 2013 Elsevier B.V. All rights reserved.