Synthesis and characterization of 5-amino-2-((3-hydroxy-4-((3-hydroxyphenyl) phenyl) diazenyl) phenol and its Cu(II) complex – a strategy toward developing azo complexes for reduction of cytotoxicity

Abstract

A major drawback of azo compounds is their associated toxicity, often carcinogenic, which is related to the reduction of the azo bond. This study intends to re-investigate this behavior by studying 5-amino-2-((3-hydroxy-4-((3-hydroxyphenyl) phenyl) diazenyl) phenol (AHPD), a compound containing two azo bonds. Interaction of AHPD and its dimeric Cu(II) complex with bacterial strains Escherichia coli and Staphylococcus aureus revealed the complex was less toxic. Reductive cleavage of the azo bond in AHPD and the complex followed using cytochrome c reductase (a model azo-reductase) as well as azo-reductase enzymes obtained from bacterial cell extracts. Degradation of the azo bond was less in the complex allowing us to correlate the observed cytotoxicity. Cyclic voltammetry on AHPD and the complex support observations of enzyme assay experiments. These were particularly useful in realizing the formation of amines as an outcome of the reductive cleavage of azo bonds in AHPD that could not be identified through an enzyme assay. Results suggest that complex formation of azo compounds could be a means to control the formation of amines responsible for cytotoxicity. Studies carried out on bacterial cells for mere simplicity bear significance for multicellular organisms and could be important for human beings involved with the preparation and utilization of azo dyes.

• 5-amino-2-((3-hydroxy-4-((3-hydroxyphenyl) phenyl) diazenyl) phenol
• Mass spectroscopy
• Azo-bond cleavage
• Enzyme assay
• Cyclic voltammetry

Acknowledgements

D.G. wishes to thank the UGC, New Delhi, for a project fellowship. S.D. is grateful to Prof. Samiran Mitra of the Department of Chemistry, Jadavpur University, for kindly providing the TGA data of the compounds. D.G. remains grateful to Mr Piyal Das for his help in enzyme assay experiments.

Funding

This work was funded by the University Grants Commission, New Delhi, in the form of a Major Research Project [39-749/2010(SR)] to S.D. Funding from the UGC is gratefully acknowledged.

Supplemental data

Supplemental data for this article can be accessed at http://dx.doi.org/10.1080/2164232X.2014.883287.

Nomenclature

:

=

A dimeric complex of Cu(II) with AHPD having bridging acetates