Novel aminonaphthoquinone mannich bases derived from lawsone and their copper(II) complexes: synthesis, characterization and antibacterial activity

Journal of the Brazilian Chemical Society

Amanda P. Neves²  Cláudia C. Barbosa²  Sandro J. Greco²  Maria D. Vargas²  Lorenzo C. Visentin¹  Carlos B. Pinheiro¹  Antônio S. Mangrich¹  Jussara P. Barbosa¹  Gisela L. Da Costa¹ 

[1] ,Universidade Federal Fluminense Instituto de Química Niterói RJ ,Brazil

关键词: aminonaphthoquinones;    copper complexes;    Mannich bases;    crystal structure determination;    antibacterial activity;   

DOI  :  10.1590/S0103-50532009000400015

来源: SciELO

【 摘 要 】

A series of novel Mannich bases (HL1-HL13) derived from 2-hydroxy-1,4-naphthoquinone (lawsone), substituted benzaldehydes [C6H2R¹R²R³C(O)H] and various primary amines (NH2R4, R4 = n-butyl, benzyl, allyl, 2-furfuryl), and their Cu2+ complexes, [Cu(L1)2]-[Cu(L13)2], have been synthesized and fully characterized by analytical and spectroscopic methods. The structures of complexes 1(R¹ = R² = R³ = H; R4 = Bu), 2(R¹ = R³ = H; R² = NO2; R4= Bu) and 7 (R¹ = OH; R² = R³ = H; R4= Bu) were determined by single crystal X-ray diffraction studies. All complexes crystallize in centrosymmetric space groups, with a copper atom in the inversion centre. Two L- coordinate through the naphthalen-2-olate oxygen and secondary amine-N atoms, forming six-membered chelate rings around the copper atom in a trans-N2O2 environment; spectroscopic data confirm that the other complexes exhibit similar molecular arrangement. The antimicrobial activity of all compounds has been tested on seven different strains of bacteria: Bacillus cereus, Bacillus subtilis, Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae, Pseudomonas aeruginosaand Staphylococcus aureus. In general, Mannich bases were more active than complexes, HL11(R¹ = OH; R² =H; R³ = Me; R4= Bn) and HL13(R¹ = OH; R² = H; R³ = Br; R4= Bn) being the most potent inhibitors. The MIC for the most active compound HL11against S. Coliwas 20 µmol L-1 (8 µg mL-1), better than Chloramphenicol (90 µmol L-1) and well below most values reported for other naphthoquinones.

【 授权许可】

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