Synthesis, characterization, antibacterial and cytotoxic study of platinum (IV) complexes

Potentiating-antibiotic activity and absorption, distribution, metabolism, excretion and toxicity properties (ADMET) analysis of synthetic thiadiazines against multi-drug resistant (MDR) strains

BACKGROUND

Thiadiazines are heterocyclic compounds that contain two nitrogen atoms and one sulfur atom in their structure. These synthetic molecules have several relevant pharmacological activities, such as antifungal, antibacterial, and antiparasitic.

OBJECTIVES

The present study aimed to evaluate the possible in vitro and in silico interactions of compounds derived from thiadiazines.

METHODS

The compounds were initially synthesized, purified, and confirmed through HPLC methodology. Multi-drug resistant bacterial strains of Staphylococcus aureus 10 and Pseudomonas aeruginosa 24 were used to evaluate the direct and modifying antibiotic activity of thiadiazine derivatives. ADMET assays (absorption, distribution, metabolism, excretion, and toxicity) were conducted, which evaluated the influence of the compounds against thousands of macromolecules considered as bioactive targets.

RESULTS

There were modifications in the chemical synthesis in carbon 4 or 3 in one of the aromatic rings of the structure where different ions were added, ensuring a variability of products. It was possible to observe results that indicate the possibility of these compounds acting through the cyclooxygenase 2 mechanism, which, in addition to being involved in inflammatory responses, also acts by helping sodium reabsorption. The amine group present in thiadiazine analogs confers hydrophilic characteristics to the substances, but this primary characteristic has been altered due to alterations and insertions of other ligands. The characteristics of the analogs generally allow easy intestinal absorption, reduce possible hepatic toxic effects, and enable possible neurological and anti-inflammatory action. The antibacterial activity tests showed a slight direct action, mainly of the IJ23 analog. Some compounds were able to modify the action of the antibiotics gentamicin and norfloxacin against multi-drug resistant strains, indicating a possible synergistic action.

CONCLUSIONS

Among all the results obtained in the study, the relevance of thiadiazine analogs as possible coadjuvant drugs in the antibacterial, anti-inflammatory, and neurological action with low toxicity is clear. Need for further studies to verify these effects in living organisms is not ruled out.

Phenalenyl based platinum anticancer compounds with superior efficacy: design, synthesis, characterization, and interaction with nuclear DNA

New and efficacious phenalenyl based Pt(ii) compounds have been used to design an “easy to use tool” for mechanistic understanding.

New Platinum(IV) and Palladium(II) Transition Metal Complexes of s-Triazine Derivative: Synthesis, Spectral, and Anticancer Agents Studies

New Pd(II) and Pt(IV) triazine complexes [Pt₃(L¹)₂(Cl)₉(H₂O)₃].3Cl.3H₂O (1), [Pt₃(L²)₂(Cl)₉(H₂O)₃].3Cl (2), [Pt₃(L³)₂(Cl)₉(H₂O)₃].3Cl (3), [Pt₂(L⁴)₂(Cl)₆(H₂O)₂] .2Cl.4H₂O (4), [Pd₃(L¹)₂(H₂O)₆] .3Cl₂ (5), [Pd₃(L²)₂(H₂O)₆].3Cl₂ (6), [Pd₃(L³)₂(H₂O)₆].3Cl₂ (7), and [Pd₂(L⁴)₂(H₂O)₄].2Cl₂ (8) were synthesized and well characterized using elemental analyses, molar conductance, IR, UV-Vis, magnetic susceptibility, ¹H, ¹³C-NMR spectra, and thermal analyses. These analyses deduced that the L¹, L², and L³ ligands act as tridentate forming octahedral geometry with Pt(IV) metal ions and square planar geometry in case of Pd(II) complexes but the L⁴ ligand acts as bidentate chelate. The molar conductance values refer to the fact that all the prepared s-triazine complexes have electrolyte properties which are investigated in DMSO solvent. Surface morphology behaviors of prepared complexes have been scanned using TEM. The crystalline behavior of triazine complexes has been checked based on X-ray powder diffraction patterns. The antimicrobial activity of the free ligands and their platinum(IV) and palladium(II) complexes against the species Staphylococcus aureus (G+), Escherichia coli (G−), Aspergillus flavus, and Candida albicans has been carried out and compared with the standard one. The coordination of ligands towards metal ions makes them stronger bacteriostatic agents, thus inhibiting the growth of bacteria and fungi more than the free ligands. The cytotoxic assessment IC₅₀ of the free ligands and its platinum(IV) complexes in vitro against human colon and lung cancer cell lines introduced a promising efficiency.

Synthesis and Characterization of Platinum (IV) complexes with S-alkyl Derivatives of Thiosalicylic Acid and the Crystal Structure of the S-butyl Derivative of Thiosalicylic Acid

New platinum(IV)-complexes with S-alkyl derivatives of thiosalicylic acid (alkyl = benzyl-(L1), methyl-(L2), ethyl-(L3), propyl-(L4), butyl-(L5)) have been synthesized and characterized by microanalysis, infrared spectroscopy, and 1H and 13C NMR spectroscopy. Th e bidentate S,O ligand precursor, the S-butyl derivative of thiosalicylic acid (S-bu-thiosal), was prepared, and its crystal structure was determined. Single crystals suitable for X-ray measurements were obtained by slow crystallization from a DMSO-water system. S-bu-thiosal crystallized in a P21/c space group of a monoclinic crystal system with a = 8.0732 (3) Å, b = 19.6769 (4) Å, c = 8.2291 (3) Å and Z = 4. S-bu-thiosal also has a coplanar geometry.

Antimicrobial Efficacy and Synergy of Metal Ions against Enterococcus faecium, Klebsiella pneumoniae and Acinetobacter baumannii in Planktonic and Biofilm Phenotypes

The effects of metal ion solutions (silver, copper, platinum, gold and palladium) were determined individually and in combination against Enterococcus faecium, Acinetobacter baumannii and Klebsiella pneumoniae. Platinum, gold and palladium showed the greatest antimicrobial efficacy in zone of inhibition (ZoI) assays. When tested in combinations using ZoI assays, gold/platinum, gold/palladium and platinum/palladium were indicative of synergy. Microbial inhibitory concentration demonstrated platinum and gold against Enterococcus faecium, platinum against Klebsiella pneumoniae and platinum and silver against Acinetobacter baumannii were optimal. Minimal bactericidal concentrations determined the greatest bactericidal activity was again platinum gold and palladium against all three bacteria. Fractional Inhibitory Concentration (FIC) studies demonstrated that the silver/platinum combination against Enterococcus faecium, and silver/copper combination against Acinetobacter baumannii demonstrated antimicrobial synergy. Following crystal violet biofilm assays for single metal ion solutions, antimicrobial efficacies were demonstrated for all the metals against all the bacteria Synergistic assays against biofilms demonstrated gold/palladium, gold/platinumand platinum/palladium resulted in the greatest antimicrobial efficacy. Overall, platinum, palladium and gold metal ion solutions in individual use or combination demonstrated the greatest antimicrobial efficacies against planktonic or biofilm bacteria. This work demonstrates the potential for using a range of metal ions, as biocidal formulations against both planktonic or biofilm bacteria.

Nickel(II) thiohydrazide and thiodiamine complexes: synthesis, characterization, antibacterial, antifungal and thermal studies

Nickel(II) complexes of type [Ni(L)(2)Cl(2)] and [Ni(L)(2)(OCOCH(3))(2)], where L=N,N-diphenyl-N-thiohydrazide (L(1)) and (N,N-diphenyl-N-thio)-1,3-propanediamine (L(2)), have been synthesized. The thiodiamines coordinate as a bidentate N-S ligand. The synthesized nickel(II) complexes of the thiodiamines were characterized by elemental analysis, IR, mass, electronic and (1)H NMR spectroscopic and TG/DTA studies. Various kinetic and thermodynamic parameters like order of reaction (n), activation energy (E(a)), apparent activation entropy (S(#)) and heat of reaction (DeltaH) have also been carried out for one complex. These complexes were also screened for in vitro antifungal and in vitro antibacterial activities and significant activity have been found.

Synthesis, Characterization, and Antibacterial and Cytotoxic Study of Metal Complexes with Schiff Base Ligands

The synthesis of 16 metal complexes from four Schiff bases prepared from 5-chloro-2-hydroxybenzaldehyde and primary amines has been described. The synthesized Schiff base ligands and their complexes were characterized by elemental analyses, spectroscopic (UV, IR, 1H and 13C NMR, electrospray ionization-mass spectrometry) methods, and magnetic and conductance measurements. Furthermore, complexes 1a, 1b, 3d, 4a, and 4d were characterized by X-ray diffraction analysis. After the structural characterization, all the compounds were tested in vitro for their antibacterial (Bacillus subtilis, Escherichia coli, Pseudomonas fluorescens, and Staphylococcus aureus) activities. The cytotoxic activities of the synthesized compounds were evaluated in vitro against human chronic myeloid leukaemia cells (K562) and a human nasopharyngeal epidermoid tumour cell line. The results indicated that most of the complexes showed good cytotoxic activity against human cancer cell lines but weak cytotoxic activity against a human normal cell line (L02). Among the compounds tested, the cobalt complexes 1a, 2a, 3a, and 4a showed the most favourable antibacterial and cytotoxic activities.

Synthesis, characterization, cytotoxicity, antibacterial and antifungal evaluation of some new platinum (IV) and palladium (II) complexes of thiodiamines

Some new platinum (IV) and palladium (II) thiodiamine complexes of type [Pt(L)2Cl2] and [Pd(L)Cl2], [where, L=(cyclohexyl-N-thio)-1,2-ethylenediamine (L(1)) and (cyclohexyl-N-thio)-1,3-propanediamine (L(2))] have been synthesized. The thiodiamines coordinate as a bidentate N-S ligand. The synthesized platinum (IV) and palladium (II) complexes of the thiodiamines were characterized by elemental analysis, IR, mass, electronic and (1)H NMR spectroscopic studies. These complexes were also screened for cytotoxicity, in vitro antifungal and in vitro antibacterial activities. Thermodynamic parameters such as activation energy (Ea), apparent activation entropy (S(#)) and enthalpy change (DeltaH) for the dehydration and decomposition reactions of one complex has also been evaluated.

Determination of the cation-chelating potential of C-methylthiolated beta-lactams and their sulfones by electrospray ionization mass spectrometry

The chelation potential of highly lipophilic C-dimethylthiolated monocyclic beta-lactams was examined using electrospray ionization mass spectrometry (ESI-MS). The metal salts NaCl, KCl, CaCl2, ZnCl2, Cu(NO3)2, CdSO4, MnCl2, and Mg(NO3)2 were used for the analysis. The K+ adducts of the compounds studied were more responsive in ESI analysis, compared to their Na+ adducts, regardless of the oxidation state of the sulfur (in the methylthio or the sulfone groups) and the type of the group adjacent to the lactam carbonyl. Opening of the beta-lactam ring, leading to formation of a chargeable N-atom, had little to no effect on the K+ adduct formation. Interactions of the methylthio group with the divalent zinc ion were also observed.