Synthesis and Biological Activity of Pd(II) and Cu(II) Complexes with Acylhydrazones of Usnic Acid

Abstract

The complexes of Pd(II) and Cu(II) with the condensation products of usnic acid with hydrazides were prepared and characterized by elemental analyses, IR, ¹H NMR, and ¹³C NMR spectroscopy. In all cases, the complexes appear to be monomeric and square‐planar, with three binding sites occupied by the dianionic tridentate ligand, and the fourth position occupied by ethanol. The complexes were tested for in vitro growth inhibitory activity against Aspergillus niger, Escherichia coli, Pseudomonas aeruginosa, and Bacillus subtilis and were found to possess significant activity. The cytotoxic tests were carried out by utilization of the MTT (3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2H‐tetrazolium bromide) microculture colorimetric assay in which human cervix carcinoma HeLa cells were treated by continuous exposure (48 h) to the test agents. All investigated compounds showed cytotoxic activity against HeLa cells with IC₅₀ values between 1.8 and 86.0 µM.

Keywords:

• Usnic acid
• Pd(II) complex
• Cu(II) complex
• Biological activity
• Synthesis

Acknowledgments

This work was supported by the Ministry of Science, Technology and Development. Project name: Synthesis, Characterisation, Structure and Biological Activity of Metal Complexes with Synthetic and Natural Organic Ligands. Project No. 1713.