Platinum(II) and palladium(II) complexes of pyridine-2-carbaldehyde thiosemicarbazone as alternative antiherpes simplex virus agents

Thiosemicarbazides: Updates on Antivirals Strategy

The challenges of viral infection have increased in recent decades due to the emergence of resistance, cross-resistance and drying up of antiviral drug discovery. Many neglected tropical viruses including the chikungunya virus, dengue virus & Japanese encephalitis virus have gradually become global pathogens. This has further increased the burden of viral infection which necessitates the continuous development of antiviral therapy. The antiviral chemistry began with the development of thiosemicarbazide derived thiosemicarbazones as antiviral. Although very few thiosemicarbazides have progressed into clinical application, it still inspires antiviral development. During last 3 decades (1990- 2020), several efforts have been made to develop suitable antiviral by using thiosemicarbazide scaffold. Its hybridization with other pharmacophores has been used as a strategy to enhance safety and efficacy. Cyclization and substitution of thiosemicarbazides have also been used to develop potent antiviral. With the ability to form coordinate bonds, thiosemicarbazides have been used either as metal complex or chelator against viruses. This work is an attempt to systematically review the research on the use of thiosemicarbazides as an antiviral scaffold. It also reviews the structure-activity relationship and translational suitability of thiosemicarbazide derived compounds.

[Cytotoxic effect of palladium (II) inclusion compounds in beta-cyclodextrin]

INTRODUCTION

Thiosemicarbazones and palladium (II) complexes have antineoplastic activities with mild side effects, for which they are considered new alternative antineoplastic drugs. However, the IC50 ranges of these complexes vary due to differences in their structure and solubility and their sensitivities for various cellular targets. Beta-cyclodextrin is an additive used to improve the solubility and stability of various drugs for therapeutic use, but the combination of beta-cyclodextrin with palladium (II) complexes and thiosemicarbazones has not been tested yet.

OBJECTIVE

To study the cytotoxic effect of palladium (II) inclusion complexes in beta-cyclodextrin.

MATERIALS AND METHODS

We tested the cytotoxic activity of palladium complexes combined with beta-cyclodextrin in the breast cancer cell line MCF-7 using a sulforhodamine B assay.

RESULTS

We tested the antiproliferative activity of palladium (II) complexes with and without the ligands MePhPzTSC and Ph2PzTSC and with and without beta-cyclodextrin in MCF-7 cells and compared them to that of cisplatin. All combinations showed antiproliferative activity; however, the activity was greater for the combinations that included beta-cyclodextrin: ([Pd (MePhPzTSC) 2] • ß-CD and [Pd (Ph2PzTSC) 2] • ß-CD), at concentrations of 0.14 and 0.49 μM, respectively. The IC50 for this complex was 5-fold lower than that of the ligand-free combinations (1.4 and 2.9 μM, respectively). The IC50 for free palladium (II) complex was 0.571.24 μM and that for cisplatin was 6.87 μM.

CONCLUSIONS

Beta-cyclodextrin significantly enhanced the cytotoxic activities of palladium (II) complexes and thiosemicarbazones probably by improving their solubility and bioavailability. The addition of beta-cyclodextrin is a possible strategy for designing new anticancer drugs.

(E)-2-[1-(3-Chloro-4-fluoro-phen-yl)ethyl-idene]hydrazinecarbothio-amide

In the crystal of the title compound, C(9)H(9)ClFN(3)S, the molecules are inter-connected by N-H⋯S and N-H⋯F hydrogen bonds. There are two different N-H⋯S hydrogen bond: the stronger one links mol-ecules into infinite chains along the b axis with graph-set motif C(4), while the weaker N-H⋯S hydrogen bond combines with the previous one into an R(2) (2)(8) network. Moreover, the chains are linked into layers parallel to (102) by weak N-H⋯F hydrogen bonds, which form an R(2) (2)(22) ring motif. In addition, there are also weak π-π inter-actions between the benzene rings of adjacent mol-ecules [centroid-centroid distance = 3.8997 (15) Å].

Organotin Compound Derived from 3-Hydroxy-2-formylpyridine Semicarbazone: Synthesis, Crystal Structure, and Antiproliferative Activity

The novel diphenyltin(IV) compound [Ph₂(HyFoSc)Sn] (2), where H₂HyFoSc (1) is 3-hydroxy-2-formylpyridine semicarbazone, was prepared and characterized by vibrational and NMR (¹H, ¹³C) spectroscopy. The structure of [Ph₂(HyFoSc)Sn] was confirmed by single-crystal X-ray crystallography. The doubly deprotonated ligand is coordinated to the tin atom through the enolic-oxygen, the azomethine-nitrogen, and phenolic-oxygen, and so acts as an anionic tridentate ligand with the ONO donors. Two carbon atoms complete the fivefold coordination at the tin(IV) center. Intermolecular hydrogen bonding, C–H → π, and π → π interactions combine to stabilize the crystal structure. Compounds 1 and 2 have been evaluated for antiproliferative activity in vitro against the cells of three human tumor cell lines: MCF-7 (human breast cancer cell line), T24 (bladder cancer cell line), A549 (nonsmall cell lung carcinoma), and a mouse fibroblast L-929 cancer cell line.

Cytotoxicity and effects of 1,10-phenanthroline and 5-amino-1,10-phenanthroline derivatives on some immunocompetent cells

The biological activity of previously synthesized compounds [(phen)(3)(H(+))(2)(NO(3)(-))(2) (1), Pd(5-NH(2)-phen)(2)(NO(3))(2) (2) and Pd(phen)(2)(NO(3))(2)(H(2)O) (3)] was investigated in vivo. The three compounds did not show any histological alterations in the observed lung, liver, spleen and lymph nodes of White Wistar rats. The propidium iodine staining did not discover any cytotoxic effect of the tested derivatives. The tests for immunological response predominantly showed stimulation of the antibody-producing B-cells and lower or no stimulation of the T-cells. The LIF-test showed better stimulation of all lymphocytes with 1, followed by 2 and 3. Substance 3 showed highest stimulating effect on B-cell blood lymphocytes in all doses (maximum in the lowest dose), whereas the impact of 2 is weaker and that of 1 is the weakest. The T-cell immune response after treatment with substance 1 is best influenced by dose of 1mg in the spleen cell-fraction, followed by 3 (5 mg).

Synthesis, characterization, and in vitro cytotoxic activities of benzaldehyde thiosemicarbazone derivatives and their palladium (II) and platinum (II) complexes against various human tumor cell lines

The palladium (II) bis-chelate Pd (L¹⁻³)₂ and platinum (II) tetranuclear Pt₄(L⁴)₄ complexes of benzaldehyde thiosemicarbazone derivatives have been synthesized, and characterized by elemental analysis and IR, FAB(+)-mass and NMR (¹H, ¹³C) spectroscopy. The complex Pd(L²)₂ [HL² = m-CN-benzaldehyde thiosemicarbazone] shows a square-planar geometry with two deprotonated ligands (L) coordinated to Pd^II through the nitrogen and sulphur atoms in a transarrangement, while the complex Pt₄(L⁴)₄ [HL⁴ = 4-phenyl-1-benzaldehyde thiosemicarbazone] has a tetranuclear geometry with four tridentate ligands coordinated to four Pt^II ions through the carbon (aromatic ring), nitrogen, and sulphur atoms where the ligands are deprotonated at the NH group. The in vitro antitumor activity of the ligands and their complexes was determined against different human tumor cell lines, which revealed that the palladium (II) and platinum (II) complexes are more cytotoxic than their ligands with IC₅₀ values at the range of 0.07–3.67 μM. The tetranuclear complex Pt₄(L⁴)₄, with the phenyl group in the terminal amine of the ligand, showed higher antiproliferative activity (CI₅₀ = 0.07–0.12 μM) than the other tested palladium (II) complexes.

(E)-4-(Benz-yloxy)benzaldehyde thio-semicarbazone

In the title compound, C(15)H(15)N(3)OS, the thio-semicarbazone group adopts an E configuration with respect to the C=N bond. The benzaldehyde thio-semicarbazone fragment is almost planar [maximum deviation = 0.012 (1) Å], while the dihedral angle between the benz-yloxy and phenyl rings is 72.48 (5)°. In the crystal structure, mol-ecules are inter-connected by N-H⋯N and N-H⋯S hydrogen bonds, forming a two-dimensional network parallel to the bc plane and are further stacked along the a axis by π-π inter-actions [centroid-centroid separation 3.9043 (7) Å]. The crystal structure is also stabilized by C-H⋯π inter-actions.