Synthesis, Characterization and Evaluation of the Antibacterial and Antitumor Activity of HalogenatedSalen Copper (II) Complexes derived from Camphoric Acid

Ana Salomé Pires, João Batista, Dina Murtinho, Célia Nogueira, Anna Karamysheva, M. Luísa Ramos, Bruce F. Milne, Nuno Tiago Tavares, José Gonçalves, Ana Cristina Gonçalves, Ana Margarida Abrantes, Rui Soares, Teresa Gonçalves, Maria Filomena Botelho, M. Elisa Silva Serra

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11 Citations (Scopus)


Platinum metal complexes are the most common chemotherapeutics currently used in cancer treatment. However, the frequent adverse effects, as well as acquired resistance by tumor cells, urge the development of effective alternatives. In the recent past, copper complexes with Schiff base ligands have emerged as good alternatives, showing interesting results. Accordingly, and in continuation of previous studies in this area, three new camphoric acid-derived halogenated salen ligands and their corresponding Cu (II) complexes were synthesized and their antitumor activity was evaluated in order to determine the influence of the type and number of halogens present (Br, Cl). The in vitro cytotoxic activity was screened against colorectal WiDr and LS1034 and against breast MCF-7 and HCC1806 cancer cell lines. The results proved the halogenated complexes to be very efficient, the tetrachlorinated Cu (II) complex being the most promising, presenting IC 50 of 0.63–1.09 μM for the cell lines studied. The complex also shows selectivity to colorectal cancer cells compared to non-tumor colon cells. It is worth highlighting that the tetrachlorinated Cu (II) complex, our most efficient complex, shows a significantly more powerful antitumor effect than the reference drugs currently used in conventional chemotherapy. The halogenated salen and corresponding complexes were also screened for their antimicrobial activity against four bacterial species-Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa-and four fungal species-Candida albicans, Candida glabrata, Aspergillus fumigatus and Alternaria alternata. The compounds were found to exhibit moderate to strong antibacterial activity against the bacterial strains studied. NMR studies and theoretical calculations provided some insight into the structure of the ligands and copper complexes. Considering the results presented herein, our work validates the potential use of copper-based chemotherapeutics as alternatives for cancer treatment.

Original languageEnglish
Article numbere5569
Number of pages18
JournalApplied Organometallic Chemistry
Issue number5
Early online date3 Feb 2020
Publication statusPublished - 3 Apr 2020

Bibliographical note

Foundation for Science and Technology (FCT), Portugal (Strategic Projects UID/NEU/04539/2013 and UID/NEU/04539/2019) and COMPETE-FEDER (POCI-01-0145-FEDER-007440). UC-NMR facility supported in part by FEDER–European Regional Development Fund through the COMPETE Program and by National Funds by FCT, through grants REEQ/481/QUI/2006, RECI/QEQ-QFI/0168/2012, CENTRO-07-CT62-FEDER-002012, and the Rede Nacional de Ressonância Magnética Nuclear (RNRMN). B.F.M. thanks the Portuguese Foundation for Science and Technology (Projects CENTRO-01-0145-FEDER-000014 and POCI-01-0145-FEDER-032229) and the Donostia International Physics Centre for financial support.


  • copper salens
  • cytotoxic activity
  • antimicrobial activity
  • NMR studies
  • ligand geometry optimization


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