Antimicrobial activity of mono- and polynuclear platinum and palladium complexes

Stabilized Palladium Nanoparticles from Bis-(N-benzoylthiourea) Derived-PdII Complexes as Efficient Catalysts for Sustainable Cross-Coupling Reactions in Water

Stable palladium (II) complexes, incorporating a double (N-benzoylthiourea) arrangement bonded to a complex heterocyclic scaffold, are used as precursors of catalytic species able to promote Suzuki-Miyaura, Mizoroki-Heck, Hiyama, Buchwald-Hartwig, Hirao and Sonogashira-Hagihara cross-coupling transformations in water. These sustainable processes are chemoselective and very versatile. The nanoparticles responsible for these catalytic reactions were analyzed and studied. Their usefulness is demonstrated after several tests and analyses. The heterogeneous character of this species in water was also confirmed.

Preparation of a Pt(II)-3-Hydroxy-2-tolyl-4H-chromen-4-one Complex Having Antimicrobial, Anticancerous, and Radical Scavenging Activities with Related Computational Studies

A novel benzopyran-based platinum (II)-3-hydroxy-2-tolyl-4H-chromen-4-one (HToC) complex has been prepared and studied by UV-visible spectrophotometry. The study is based on the colored complexation between Pt(II) and HToC in the pH range of 8.92-9.21, resulting in the formation of a stable binary yellow complex exhibiting λmax at 509-525 nm. The formed complex maintains linearity between 0.0 and 1.8 μg Pt(II) mL-1. The well-known qualitative analytical methods, including Job's method of continuous variations and the mole ratio approach, have both proven that the stoichiometry of the complex is 1:2 [Pt(II)/HToC]. Hence, the analytical results suggest that the formed platinum complex exhibits a square planar geometry. The values of various attributes corresponding to spectrophotometric studies and statistical calculations, such as the molar extinction coefficient (6.790 × 104 L mol-1 cm-1), Sandell's sensitivity (0.0029 μg Pt(II) cm-2), standard deviation (± 0.0011), RSD (0.317%), limit of detection (0.0147 μg mL-1) and correlation coefficient (0.9999), show that the performed study satisfies all of the criteria for good sensitivity, versatility, and cost-effectiveness. In order to have an apprehension of the molecular geometry and other structural specifics of the complex, DFT studies have been carried out. The in vitro anticancer potential of the ligand and its platinum complex in the human breast cancer cell line (T-27D), as determined by the MTT assay, reveals that the complex has better antiproliferative potential than the ligand. The antimicrobial potential of the complex has been successfully tested against both Gram-positive and -negative bacteria. Antioxidant capacity results suggest the better radical scavenging capacity of the complex than that of the ligand.

Antimicrobial Resistance Challenged with Platinum(II) and Palladium(II) Complexes Containing 1,10-Phenanthroline and 5-Amino-1,3,4-Thiadiazole-2(3H)-Thione in Campylobacter jejuni

This work describes the synthesis and characterization of two metal complexes of the type [M(L1)2(phen)], where M = Pt2+ (complex I) or Pd2+ (complex II), L1 = 5-amino-1,3,4-thiadiazole-2(3H)-thiolate and phen = 1,10-phenanthroline. The in vitro antibacterial activity of these complexes was investigated in isolation and synergistically with ciprofloxacin (CIP) and erythromycin (ERY) in three strains of Campylobacter jejuni (MIC = 32 mg/L for CIP and ERY), selected from a bank of 235 strains representative of three poultry exporting states of the country (A, B and C), previously analyzed for epidemiology and resistance to CIP and ERY. A total of 53/235 (22.55%) strains showed co-resistance to CIP and ERY. Isolated resistance to CIP was higher than to ERY. Epidemiological analysis showed that resistance to CIP was more evident in state B (p < 0.0001), as well as a higher susceptibility to ERY in state C (p = 0.0028). Co-resistance was expressive in state A and in the spring and fall seasons. The evaluation of I alone and in synergy with CIP and ERY found values up to 0.25 mg/L not significant for ERY. Complex II did not show an antimicrobial effect on the three strains of tested C. jejuni. The effect provided by complex I represents a promising alternative for control of resistant strains of C. jejuni.

Structure and properties of antimicrobial peptides produced by antagonist microorganisms isolated from Siberian natural objects

Introduction. Public healthcare urgently needs new pharmaceuticals – alternative to traditional antibiotics – that pathogens develop no resistance to. Of special interest in this regard are antimicrobial, ribosomally synthesized bacterial peptides or bacteriocins. In this work, we aimed to study the structure and properties of antimicrobial peptides produced by antagonist microorganisms isolated from the natural objects of the Siberian region. Study objects and methods. The study objects were bacteria isolated from the natural sources of Kuzbass. After culturing bacteria, total protein was precipitated from the culture fluid and separated into fractions by gel permeation HPLC. Their amino acid sequences were determined by MALDI-TOF mass spectrometry. The antibacterial (against Bacillus pumilus and Escherichia coli) and fungicidal (against Aspergillus flavus and Aspergillus niger) properties of the peptides were studied by the disk diffusion method. Results and discussion. Seven peptides with different amino acid sequences were isolated from the culture fluid of bacteria, five of which had no analogues in the PepBank and Uniprot data banks. The peptide with an amino acid sequence of VMCLARKCSQGLIVKAPLM (2061.66 Da) was homologous to the cysteine membrane protein Giardia lamblia P15, and the peptide with an amino acid sequence of AVPSMKLCIQWSPVRASPCVMLGI (2587.21 Da) showed a homology with the Planctomycetes bacterium I41 peptides. We found antibacterial (against gram-positive and gram-negative bacteria) and fungicidal (against Aspergillus) properties in the peptide fractions. Conclusion. Antimicrobial peptides produced by bacteria isolated from the natural objects of the Siberian region can be used to create pharmaceuticals as an alternative to traditional antibiotics to treat infectious diseases.