Preparation, Characterization and Antioxidant Evaluation of Cu(II) and Zn(II) Tannates

Gessyca Gonçalves Costa1, Camila Cíntia Sousa Melo Brito2, Ailton José Terezo2, Adriana de Paula Cardoso2, Elias Yuki Ionashiro3, Adriano Buzutti de Siqueira2, *
1 Faculty of Pharmacy, Federal University of Goiás (UFG), Goiânia, Goiás, Brazil
2 Department of Chemistry, Federal University of Mato Grosso (UFMT), Cuiabá, Mato Grosso, Brazil
3 Institute of Chemistry, Federal University of Goiás (UFG), Goiânia, Goiás, Brazil



The interest in the antioxidant materials increased due to their free radical scavenging properties avoiding various pathologies. Tannic acid (TA) is known to have high free radical scavenging activity, but its application is still limited.

This paper had the objective of synthesis, characterization and evaluation of free radical scavenging activity of TA associated with Cu (II) and Zn (II) ions, in a buffered aqueous medium.

Methods and Materials:

Techniques of FTIR, simultaneous TG-DSC characterized the obtained compounds, and the evaluation of free radical scavenging activity was made using 2,2–diphenyl–1–picrylhydrazyl (DPPH) radical. The FTIR analysis of the compounds showed significant displacement of the main bands in the TA spectrum (νC=O, δO-H, σO-H), suggesting an association of metal ions with the oxygen of the hydroxyl group of TA. TG-DSC curves showed information about the thermal stability, stoichiometry, hydration water, and residues formation.

Results and Conclusion:

The TA association with the metal ions Cu(II) and Zn(II) decreased the antioxidant activity of the molecule significantly, showing that these compounds could be potentially used as pro-oxidant agents.

Keywords: Thermal analysis, Tannic acid, Copper, Zinc, Antioxidant.

Abstract Information

Identifiers and Pagination:

Year: 2018
Volume: 5
Publisher Item Identifier: EA-CHEM-2018-11

Article History:

Received Date: 6/6/2018
Revision Received Date: 7/11/2018
Acceptance Date: 9/11/2018
Electronic publication date: 26/11/2018
Collection year: 2018

© 2018 Costa et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Correspondence: Address correspondence to this author at the Department of Chemistry, Federal University of Mato Grosso (UFMT), Rua Consolação, n. 321, Coophema, Cuiabá, Mato Grosso, Brazil; Tel: 6584357708; E-mail: