New 8-hydroxyquinoline metallodrugs: synthesis, speciation and uptake

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Cu(II) and V(IV)O complexes with tri- or tetradentate ligands based on (2-hydroxybenzyl)- L-alanines reveal promising anticancer therapeutic potential

Publication . Ribeiro, Nádia; Bulut, İpek; Cevatemre, Buse; Teixeira, Carlos; Yildizhan, Yasemin; André, Vânia; Adão, Pedro; Pessoa, João; Acilan, Ceyda; Correia, Isabel

Four new ligand precursors (H2L1–H2L4), derived from the Mannich condensation of two amino acids (L-Val and L-Phe) and two 3,5-disubstituted phenols (t-Bu or Me), and the corresponding oxidovanadium(IV) (1–4) and copper(II) (6–7) complexes are synthesized. Two other related compounds (H2L5 and H2L6), containing an additional 2-methyl-pyridine arm, and the corresponding VIVO (5) and CuII (8–9) complexes were also obtained. All metal complexes are monomeric in the solid state, having a solvent molecule or a chloride ion in the coordination sphere. The in vitro cytotoxic activity of all compounds is evaluated against cancer cells from different origins. The IC50 values at 72 h are in the range of 6–15 μM for HeLa cells, 4–17 μM for A-549 cells and >25 μM for MDA-MB-231 cells, except for [VIVOL1(CH3OH)] (1) and [CuL6(H2O)] (9). With the exception of H2L6, overall, the metal complexes are more cytotoxic than the corresponding ligand precursors. Globally, the cellular viability data show that (i) the L-Phe derived compounds are more cytotoxic than the corresponding L-Val complexes; (ii) the presence of the bulkier t-Bu groups increases the cytotoxicity; (iii) the presence of a 2-methyl pyridine arm increases considerably the cytotoxicity; and (iv) the CuII-complexes are more cytotoxic than the VIVO-compounds. Complexes [VIVOL3(CH3OH)] (3), [CuL3(H2O)] (7) and [CuL5(H2O)] (8) were further evaluated and their mechanism of action was determined to be apoptosis, evidenced by AnnexinV staining and the increase in caspase 3/7 activity. Compounds 3, 7 and 8 also exhibit DNA cleavage activity, involving the formation of reactive oxygen species and were able to induce genomic damage in cells as determined by COMET assay.

2021Journal article

Restricted access

Enhancement of the antioxidant and antimicrobial activities of porphyran through chemical modification with tyrosine derivatives

Publication . Adão, Pedro; Reboleira, João; Teles, Marco; Santos, Beatriz; Ribeiro, Nádia; Teixeira, Carlos M.; Guedes, Mafalda; Pessoa, João Costa; Bernardino, Susana M.

The chemical modification of porphyran hydrocolloid is attempted, with the objective of enhancing its antioxidant and antimicrobial activities. Sulfated galactan porphyran is obtained from commercial samples of the red algae Porphyra dioica using Soxhlet extraction with water at 100ºC and precipitation with isopropyl alcohol. The extracted porphyran is then treated with modified L-tyrosines in aqueous medium in the presence of NaOH, at ca. 70ºC. The modified tyrosines L1 and L2 are prepared through a Mannich reaction with either thymol or 2,4-di-tert-butylphenol, respectively. While the reaction with 2,4-di-tert-butylphenol yields the expected tyrosine derivative, a mixture of products is obtained with thymol. The resulting polysaccharides are structurally characterized and the respective antioxidant and antimicrobial activities are determined. Porphyran treated with the N-(2-hydroxy-3,5-di-tert-butyl-benzyl)-L-tyrosine derivative, POR-L2, presents a noticeable superior radical scavenging and antioxidant activity compared to native porphyran, POR. Furthermore, it exhibited some antimicrobial activity against S. aureus. The surface morphology of films prepared by casting with native and modified porphyrans is studied by SEM/EDS. Both POR and POR-L2 present potential applicability in the production of films and washable coatings for food packaging with improved protecting characteristics.

2021Journal article

Open access