Palladium(II) complexes with tris(2-carboxyethyl)phosphine, structure, reactions and cytostatic activity

Reactivity of NiII, PdII and PtII complexes bearing phosphine ligands towards ZnII displacement and hydrolysis in Cis2His2 and Cis3His zinc-fingers domains

A systematic study of the effect of phosphine and bis-phosphine ligands in the interaction of Ni^II, Pd^II, and Pt^II complexes with two classes of zinc fingers was performed. The Cys₂His₂, finger 3 of specific protein-1, and the Cys₂HisCys C-terminal zinc finger of nucleocapsid protein 7 of the HIV-1 were used as models of the respective class. In general, phosphine ligands favor the metal binding to the peptide, although the bis-phosphine ligands produce more specific binding than the monodentate. In the case of nickel complexes, the interaction of Ni^II ions with the sequence SKH, present in Cys₂His₂, results in hydrolysis, contrasting to the preferred zinc ejection produced by the Ni^II complexes with chelating phosphines, producing Ni(bis-phosphine) fingers. In the absence of the SKH sequence, zinc ejection is observed with the formation of nickel fingers, with reactivity dependent on the phosphine. On the other hand, Pd(phosphines) produces Pd₂ fingers in the case of triphenylphosphine with the phosphine coordinated as intermediate species. The bis-phosphine ligands produce very clean spectra and a stable signal Pd(bis-phosphine)finger. Interestingly, phosphines produce very reactive platinum complexes, which eject zinc and promote peptide hydrolysis. The results reported here are relevant to the understanding of the mechanism of these interactions and how to modulate metallocompounds for zinc finger interference.

Palladium (II), platinum (II) and silver (I) complexes with oxazolines: Their synthesis, characterization, DFT calculation, molecular docking and antitumour effects

Six new Pd(II), Pt(II) and Ag(I) complexes, (1);{Pd (L₁)]2C₆H₄}₂Cl₄} (2); Pt(L₂)(DMSO)Cl; 3; {PtL₅]₂C₆H₄}₂·PhCOO^-⋅11NO₃^-; 4; {[Pt(L₄)]₂C₆H₄}; the binuclear cyclometalated complex the polymer chain (5); {[PtL₅]C₆H₄}·NO₃^-}; and the polymeric silver species (6); Zn(L₆)₂·AgNO₃·CHCl₃ were synthesized and thoroughly characterized using X-ray diffraction and spectroscopic techniques (L₁=(S,S)-1,4-i-PrOx]₂C₆H₄}₂Cl₄, L₂=Di(2,2-bis(4R-isopropyl-4,5-dihydro-oxazol-2-yl)acetonitrile) zinc (II) (B_R1);L₃= 1,4-bis(4R-benzyl-4,5-dihydro-oxazol-2-yl)benzene (A_R2); L₄= 1,4-bis(4R-benzyl-4,5-dihydro-oxazol-2-yl)benzene，L₅=1,4-bis(4R-benzyl-4,5-dihydro-oxazol-2-yl)-benzene，L₆=Di(2,2-bis(4S-isopropyl-4,5-dihydrooxazol-2-yl)acetonitrile) zinc (II). Complexes 1-6 showed cytotoxic effects against human tumour cell lines, including a multidrug-resistant subline. Oxazoline and Pd complex 1 induced apoptosis in A549 cells. DFT calculations were also performed to exhibit the excellent bioactivity of complex 1 against A549, MDA-MB-231, and KB cells. Complex 1, with the best docking score and a stable interaction network within the binding site of the G-quadruplex, could stably interact with the G-quadruplex. Additionally, complex 1 was further used in the animal experiment of human lung adenocarcinoma cells in nude mice. By comparing with the model control group, the tumour volume, relative tumour volume and relative tumour proliferation rate T/C decreased significantly in the cisplatin group and compound 1 (complex 1) group.

Anticancer activity of palladium-based complexes against triple-negative breast cancer

Treatment of triple-negative breast carcinoma (TNBC) remains an unmet medical need with no targeted therapy available to date. Accounting for 10-30% of all human breast cancer tumors, this mammary carcinoma subtype has a particularly poor prognosis owing to its high metastatic potential, aggressive biology and limited pharmacological treatment options. Platinum chemotherapeutics are the mainstay therapy in patients with TNBC but their clinical use is limited by severe toxicity and acquired resistance. Palladium-based complexes are appealing alternative metal-based drugs because of significant similarities regarding structure and coordination chemistry with the platinum agents. This review summarizes the knowledge gathered so far on 121 Pd(II) complexes, emphasizing their anticancer activity and putative pharmacological targets toward TNBC.