Novel selective anticancer agents based on Sn and Au complexes. Mini-review

Cancer is one of the most common causes of death in modern medicine. Molecular design of novel substances with pharmacological activity is one of the goals of medicinal inorganic chemistry. Platinum complexes are widely used in the treatment of cancer, despite high efficacy their use is limited by side effects, as well as primary or acquired resistance. In this regard, the search for novel metal-containing antitumor compounds is underway. Organotins and gold compounds are promising pharmacological agents with anti-cancer properties. The introduction of protective antioxidant fragments into inorganic compounds molecules is a way to reduce the side effects of anti-cancer drugs on healthy cells. 2,6-dialkylphenols belonging to vitamin E (α-tocopherol) mimetics are widely used as antioxidants and stabilizers. The properties of Ph₃SnCl (Sn-I), Ph₃PAuCl (Au-I) and complexes Ph₃SnSR (Sn-II) and Ph₃PAuSR (Au-II) based on 2,6-di-tert-butyl-4-mercaptophenol (RSH) as radical scavengers and reducing agents were studied in model reactions. For Sn-II and Au-II the comparative study of cytotoxic action was made and the IC₅₀ values on different cancer cell lines were found to be depended on the nature of metal. In general, Sn(IV) complexes possessed higher cytotoxicity than Au(I) complexes. In order to clarify the mechanism of cytotoxic mode of action the effect of compounds on Fe³⁺-induced lipid peroxidation, mitochondrial potential and mitochondrial permeability, cell cycle and induction of apoptosis was studied. Organotin compounds can bind tubulin SH-groups and inhibit its polymerization by a dose-dependent mechanism, whereas gold compounds inhibit Thioredoxin reductase (TrxR). In vivo experiments on acute toxicity of Sn-II and Au-II proved their moderate toxic action that opens prospects for the further study as antitumor agents.