Synthesis, characterization, density functional theory calculations, and in vitro antibacterial activity of novel transition metal complexes containing an O3-tridentate amoxicillin-based Schiff base: A silver(II) complex as alternative against Pseudomonas aeruginosa resistant to amoxicillin

J. R. Anacona, Marcos Loroño, Daniela Marpa, Cesar Ramos, Freddy Celis

Research output: Contribution to journalArticlepeer-review

Abstract

Transition metal complexes containing an amoxicillin-based Schiff base (H2L, 3) obtained from the condensation of amoxicillin 1 with salicylaldehyde 2 were prepared. Spectroscopic and physicochemical techniques, namely, UV–visible, Fourier-transform infrared spectroscopy, 1H NMR, electron paramagnetic resonance, transmission electron microscopy, mass spectrometry, magnetic susceptibility, molar conductance, density functional theory (DFT) calculations, together with elemental and thermal analyses were used to characterize the synthesized complexes. Based on these studies, the general formulae [ML(H2O)3], where M = Mn 4, Ni 5, Zn 6, and [ML(H2O)], where M = Cu 7, Ag 8, were proposed for the complexes. The amoxicillin-based Schiff base ligand behaved as a dianionic O3-tridentate chelating agent. DFT studies and magnetic and spectral data revealed octahedral geometries for Mn, Ni, and Zn atoms and distorted tetrahedral geometries for Cu(II) and Ag(II) complexes. Synthesized compounds were tested for antibacterial activity by both agar disk diffusion method and the minimum inhibitory concentration. in vitro bacterial viability revealed that complex 5 had similar antibacterial activity as 1 against Staphylococcus aureus and Staphylococcus epidermidis, whereas Pseudomonas aeruginosa, resistant to amoxicillin, was sensitive to complex 8. The antibacterial activity of complex 8 could be attributed to its greater catalytic activity as shown by DFT calculations. Toxicity bioassay of the tested compounds showed LC50 values > 1000 ppm, indicating their nontoxicity against brine shrimp nauplii (Artemia salina).

Original languageEnglish
Article numbere5755
JournalApplied Organometallic Chemistry
Volume34
Issue number9
DOIs
StatePublished - 1 Sep 2020

Bibliographical note

Funding Information:
The authors gratefully acknowledge the support of Universidad de Oriente, Universidad Nacional Mayor de San Marcos, and Universidad de Playa Ancha.

Publisher Copyright:
© 2020 John Wiley & Sons, Ltd.

Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.

Keywords

  • DFT calculations
  • Pseudomonas aeruginosa
  • amoxicillin-based Schiff base metal complexes
  • antibacterial activity
  • silver(II) complex containing an amoxicillin-based Schiff base

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