Preparation, Characterization, Cytotoxicity and Antioxidant Activity of DOPA Melanin Modified by Amino Acids: Melanin-Like Oligomeric Aggregates

Two new synthetic melanin-like oligomers inspired by the synthesis of pheomelanin (cys-DOPA) were prepared using L-DOPA as a precursor and the amino acids serine (ser-DOPA) and threonine (thr-DOPA) for modifications. The products obtained exhibited appreciable antioxidant activity. The compounds wer...

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Published inJournal of the Brazilian Chemical Society Vol. 26; no. 2; pp. 273 - 281
Main Authors Costa, Thiago G., Feldhaus, Mateus J., Vilhena, Felipe S., Heller, Melina, Micke, Gustavo A., Oliveira, Aldo S., Brighente, Inês M. C., Monteiro, Fabiola B. F., Creczynski-Pasa, Tânia B., Szpoganicz, Bruno
Format Journal Article
LanguageEnglish
Portuguese
Published Sociedade Brasileira de Química 01.02.2015
Subjects
CHEMISTRY, MULTIDISCIPLINARY
amino acid modification
antioxidant activity
synthetic melanins
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Summary:Two new synthetic melanin-like oligomers inspired by the synthesis of pheomelanin (cys-DOPA) were prepared using L-DOPA as a precursor and the amino acids serine (ser-DOPA) and threonine (thr-DOPA) for modifications. The products obtained exhibited appreciable antioxidant activity. The compounds were characterized by liquid chromatography-mass spectrometry (LC-MS), elemental analysis and infrared spectroscopy. The pKa values of the groups present in each melanin suspension were determined in aqueous solution by potentiometric and spectrophotometric titration. Cytotoxicity assays showed an IC50 > 500 mg L-1 resulting in non-toxic compounds for living cells. Finally, cys-DOPA, ser-DOPA and thr-DOPA exhibited antioxidant activity determined by the DPPH scavenging assay, with EC50 = 7.69, 1.02 and 27.60 mg L-1, respectively.
ISSN:0103-5053
1678-4790
DOI:10.5935/0103-5053.20140277