A platinum(IV)-based metallointercalator: synthesis, cytotoxicity, and redox reactions with thiol-containing compounds

Effect of geometric isomerism on the anticancer property of new platinum complexes with glycine derivatives as asymmetric N, O donate ligands against human cancer

In this project, to fallow the anticancer ability of new Pt drugs, several new Pt complexes were synthesized with the asymmetric bidentate glycine derivatives, as named propyl- and hexyl glycine (L), in the general formula: [Pt(NH3)2(L)]NO3, and cis- and trans-[Pt(L)2]. The structure of two cis- and trans-[Pt(propylgly)2] complexes was proved by single crystallography analysis. However, all complex structures were characterized by various methods of 1H NMR, 13C NMR, 195Pt NMR, FTIR, LC-Mass, and Raman spectroscopy. To study the passage of water-soluble complexes of [Pt(NH3)2(L)]NO3 via cell membrane, their solubility, and lipophilicity were analyzed. In addition, the cytotoxic properties of these complexes were evaluated against normal and malignant cell lines (skin, breast, and lung cancer cells). The results indicated that they were either comparable to cisplatin or less damaging than carboplatin and oxaliplatin. It was expected that due to less steric effect, and the presence of length aliphatic hydrocarbon chain in the complex structure, trans-[Pt(hexylgly)2] is more toxic on cancerous cell lines than trans-[Pt(propylgly)2]. Cellular accumulation of all complexes was evaluated on A549 and MCF7 cell lines, and the amount of platinum metal (ng) was measured by the ICP method. Results showed that trans-[Pt(hexylgly)2] complex has the highest accumulation inside both mentioned cell lines and [Pt(NH3)2(L)]NO3 complexes behave like clinical Pt-drugs. Ultimately, the interaction patterns of DNA were examined using spectroscopic methods and molecular docking simulations for all substances.

Biological Activity of Two Anticancer Pt Complexes with a Cyclohexylglycine Ligand against a Colon Cancer Cell Line: Theoretical and Experimental Study

Because of their extraordinary ability to disrupt the natural structure of nucleic acids, metal complexes could be used in cancer therapy. In this study, cyclohexylglycine (HL) as a ligand and two new Pt complexes, [Pt(NH₃)₂(L)]NO₃ (1) and [Pt(bipy)(L)]NO₃ (2), were synthesized and characterized by elemental analysis, LC-MS, UV-vis spectrometry, FT-IR, ¹H NMR spectroscopy, ¹³C NMR spectroscopy, ¹⁹⁵Pt NMR spectroscopy, HPLC analysis, and single-crystal X-ray diffraction. Complex 2 crystallized in the orthorhombic Pbca space group, and density functional theory (DFT) was used to describe its structural parameters were described in detail. These complexes can be classified as oral medications and drug-like molecules based on a comparison of their absorption, distribution, metabolism, and excretion assessment. Quantum chemical descriptors (QCDs) were determined using DFT calculations to predict the tendency of DNA to approach these complexes. During the determination of the function of the metallodrug in DNA binding, the fluorescence data indicated that static quenching took place for all ligands and complexes with higher DNA binding affinity. CD and isothermal absorption studies indicate the presence of electrostatic and groove binding for the amine derivative and that DNA binds with the bipy moiety via groove binding. Furthermore, the interaction modes were determined using molecular docking to investigate the binding of these compounds with the target DNA molecule. According to docking investigations, binding energies of -5.7, -11.56, and -10.00 kcal/mol for HL and complexes 1 and 2, respectively, indicate partially electrostatic and groove binding. The anticancer activities of the Pt(II) complexes were tested against the HCT116 human colon cancer cell line, with IC₅₀ values of 35.51 and 51.33 μM for 1 and 2, respectively, after 72 h. These values show that the inhibitory effect of complex 1 was better than those of 2 and carboplatin (IC₅₀ = 51.94 μM).

Property evaluation of two anticancer candidate platinum complexes with N-isobutyl glycine ligand against human colon cancer

Small molecules have potential usage in cancer therapy due to their remarkable potency of disarranging the natural structure of nucleic acids. In this study, two complexes [Pt(NH₃)₂(IBgly)]NO₃ (1) and [Pt(bipy)(IBgly)]NO₃ (2) based on Pt(II), N-isobutylglycine (IBgly), 2,2'-bipyridine, and ammonia were prepared and characterized by spectroscopic methods. Pharmacokinetic ADME data, absorption, distribution, metabolism, excretion, and bioavailability radar showed two complexes can be introduced for Pt-based anti-cancer drugs. Mechanism of tumor inhibition and DNA interaction of these compounds was studied by UV-Vis, fluorescence, and CD spectroscopies. Also, thermodynamic parameters and the binding constants were calculated through absorption measurements. The fluorescence data showed that a static quenching mechanism occurred for both complexes with a binding constant and binding affinity towards DNA (K_b ≈ 3500 M^-1 and k_q ≈ 2.1 × 10¹¹ M^-1 s^-1). The thermodynamic parameters indicated electrostatic approaching and groove binding were more feasible than intercalation mode between Pt(II) complexes and DNA. CD spectra indicated the increasing intensity of the positive band and the negative band decreasing. Density functional theory calculations confirmed the experimental data and determined the quantum chemical descriptors including total energy, hardness, chemical potential, electrophilicity, electronegativity, etc. According to this, the binding tendency of these compounds with DNA could be predicted. Further, molecular docking studies were also performed. Docking studies revealed that the desolvation, hydrogen, and electrostatic binding were effective for the interaction between complexes and DNA with binding energy (- 10.44 and - 9.57 kcal/mol) for complexes 1 and 2, respectively, which is mainly of partially electrostatic and groove binding type. The cytotoxic activity of Pt complexes was examined against human colon cancer cell line which indicated good activity with IC₅₀ values of (41.66 and 47.30 μM) for both complexes after 72 h, respectively. Also, they demonstrated more inhibitory effects compared to carboplatin.

Apoptotic effect of novel pyrazolone-based derivative [Cu(PMPP-SAL)(EtOH)] on HeLa cells and its mechanism

Pyrazolone complexes have strong anti-tumor and antibacterial properties, but the anti-tumor mechanism of pyrazolone-based copper complexes has not been fully understood. In this study, the possible mechanism and the inhibitory effect of a novel pyrazolone-based derivative compound [Cu(PMPP-SAL)(EtOH)] on human cervical cancer cells (HeLa cells) was investigated. [Cu(PMPP-SAL)(EtOH)] effectively inhibited proliferation of HeLa cells in vitro with an IC₅₀ value of 2.082 after treatment for 72 h. Cell cycle analysis showed apoptosis was induced by blocking the cell cycle in the S phase. [Cu(PMPP-SAL)(EtOH)] promoted the loss of mitochondrial membrane potential, release of cytochrome c, PARP cleavage, and activation of caspase-3/9 in HeLa cells. Additionally, [Cu(PMPP-SAL)(EtOH)] inhibited the PI3K/AKT pathway and activated the P38/MAPK, and JNK/MAPK pathways. [Cu(PMPP-SAL)(EtOH)] also inhibited the phosphorylation of Iκ-Bα in the NF-κB pathway activated by TNF-α, thus restricting the proliferation of HeLa cells which were activated by TNF-α. In conclusion, [Cu(PMPP-SAL)(EtOH)] inhibited the growth of HeLa cells and induced apoptosis possibly via the caspase-dependent mitochondria-mediated pathway. These results suggest that [Cu(PMPP-SAL)(EtOH)] can be a potential candidate for the treatment of cervical cancer.

A study to develop platinum(iv) complex chemistry for peptide disulfide bond formation

Platinum(iv) complexes with a heterocyclic ligand and an ancillary ligand have been investigated and applied for treating various tumour cell lines. Another application of the Pt(iv) complexes in forming peptide disulfide bonds was investigated in this work. For development of Pt(iv) complex chemistry for disulfide bond formation in peptides, two Pt(iv) complexes, [PtCl₂(phen)(en)]Cl₂ and [PtCl₂(bpy)(en)]Cl₂, were synthesized and characterized using elemental analysis, ESI-MS and NMR. Subsequently, they were investigated as oxidants for the formation of disulfide bonds in various peptides. Excellent purities and yields of disulfide-containing peptides were achieved when the reactions were carried out in aqueous solution. The reactions were completed rapidly in a wide range of pH values even in acidic medium at room temperature. An intramolecular disulfide bond was formed in each of the peptides in a solution containing two dithiol-containing peptides, making the Pt(iv) complexes useful for generating disulfide-containing peptide libraries. In addition, the two Pt(iv) complexes can be used as oxidants for the synthesis of disulfide bonds on a resin, which is a more convenient method to synthesize disulfide-containing peptides through automation.

Reduction of a platinum(iv) prodrug model by sulfur containing biological reductants: computational mechanistic elucidation

In order for the usual l-Cys zwitterion to reduce Pt^IV, it is first required to tautomerise into its unusual form.

Synthesis of Reusable Silica Nanosphere-Supported Pt(IV) Complex for Formation of Disulfide Bonds in Peptides

Some peptide-based drugs, including oxytocin, vasopressin, ziconotide, pramlintide, nesiritide, and octreotide, contain one intramolecular disulfide bond. A novel and reusable monodispersed silica nanosphere-supported Pt(IV) complex (SiO₂@TPEA@Pt(IV)); TPEA: N-[3-(trimethoxysilyl)propyl]ethylenediamine) was synthesized via a four-step procedure and was used for the formation of intramolecular disulfide bonds in peptides. Transmission electron microscopy (TEM) and chemical mapping results for the Pt(II) intermediates and for SiO₂@TPEA@Pt(IV) show that the silica nanospheres possess a monodisperse spherical structure and contain uniformly-distributed Si, O, C, N, Cl, and Pt. The valence state of Pt on the silica nanospheres was characterized by X-ray photoelectron spectroscopy (XPS). The Pt(IV) loaded on SiO₂@TPEA@Pt(IV) was 0.15 mmol/g, as determined by UV-VIS spectrometry. The formation of intramolecular disulfides in six dithiol-containing peptides of variable lengths by the use of SiO₂@TPEA@Pt(IV) was investigated, and the relative oxidation yields were determined by high-performance liquid chromatography (HPLC). In addition, peptide 1 (Ac-CPFC-NH₂) was utilized to study the reusability of SiO₂@TPEA@Pt(IV). No significant decrease in the relative oxidation yield was observed after ten reaction cycles. Moreover, the structure of SiO₂@TPEA@Pt(IV) after being used for ten cycles was determined to be similar to its initial one, demonstrating the cycling stability of the complex.