Design, synthesis, crystal structure and anticancer activity of organotin(IV)-rhein carboxylates

Two new rhein-organotin complexes Ph 3 Sn(O 2 CC 14 H 7 O 4 ) ( RS01 ) and Cy 3 Sn(O 2 CC 14 H 7 O 4 ) ( RS02 ) were synthesized and characterized by elemental analysis, IR, 1 H NMR, 13 C NMR, 119 Sn NMR, X-ray crystallography and thermo-gravimetric analysis. Both complexes has a triclinic crystal system P -1 space group and one-dimensional supramolecular chain structure. The MTT results demonstrated that rhein's anticancer activity was effectively increased by introducing organotin, RS01 and RS02 exhibited excellent anticancer activity in vitro, significantly superior to cisplatin and mitoxantrone. Interestingly, despite the fact that RS01 and mitoxantrone share the same 9,10-anthraquinone scaffold structure, RS01 not only showed high anticancer activity but also much lower nephrotoxicity than mitoxantrone. Flow cytometry showed that RS01 could significantly induce cell apoptosis and arrest cell cycle in G2 phase. Molecular docking and UV–Vis absorption spectra suggested that RS01 may be intercalation with DNA. Furthermore, western blot results showed that RS01 activated the DNA damage critical protein γ -H 2 AX and regulated the expression level of the mitochondrial apoptotic pathway critical protein (Bax/Bcl-2). Thus, RS01 induced cell death may be mediated through DNA damage and mitochondrial pathways. As a result, RS01 has significant development and application potential as an anticancer agent.