A Nanostructured Lipid System as a Strategy to Improve the in Vitro Antibacterial Activity of Copper(II) Complexes
AbstractThe aim of this study was to construct a nanostructured lipid system as a strategy to improve the in vitro antibacterial activity of copper(II) complexes. New compounds with the general formulae [CuX2(INH)2]·nH2O (X = Cl− and n = 1 (1); X = NCS− and n = 5 (2); X = NCO− and n = 4 (3); INH = isoniazid, a drug widely used to treat tuberculosis) derived from the reaction between the copper(II) chloride and isoniazid in the presence or absence of pseudohalide ions (NCS− or NCO−) were synthesized and characterized by infrared spectrometry, electronic absorption spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, elemental analysis, melting points and complexometry with 2,2′,2′′,2′′′-(Ethane-1,2-diyldinitrilo)tetraacetic acid (EDTA). The characterization techniques allowed us to confirm the formation of the copper(II) complexes. The Cu(II) complexes were loaded into microemulsion (MEs) composed of 10% phase oil (cholesterol), 10% surfactant [soy oleate and Brij® 58 (1:2)] and 80% aqueous phase (phosphate buffer pH = 7.4) prepared by sonication. The Cu(II) complex-loaded MEs displayed sizes ranging from 158.0 ± 1.060 to 212.6 ± 1.539 nm, whereas the polydispersity index (PDI) ranged from 0.218 ± 0.007 to 0.284 ± 0.034. The antibacterial activity of the free compounds and those that were loaded into the MEs against Staphylococcus aureus ATCC® 25923 and Escherichia coli ATCC® 25922, as evaluated by a microdilution technique, and the cytotoxicity index (IC50) against the Vero cell line (ATCC® CCL-81TM) were used to calculate the selectivity index (SI). Among the free compounds, only compound 2 (MIC 500 μg/mL) showed activity for S. aureus. After loading the compounds into the MEs, the antibacterial activity of compounds 1, 2 and 3 was significantly increased against E. coli (MIC’s 125, 125 and 500 μg/mL, respectively) and S. aureus (MICs 250, 500 and 125 μg/mL, respectively). The loaded compounds were less toxic against the Vero cell line, especially compound 1 (IC50 from 109.5 to 319.3 μg/mL). The compound 2- and 3-loaded MEs displayed the best SI for E. coli and S. aureus, respectively. These results indicated that the Cu(II) complex-loaded MEs were considerably more selective than the free compounds, in some cases, up to 40 times higher. View Full-Text
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da Silva, P.B.; Bonifácio, B.V.; Frem, R.C.G.; Godoy Netto, A.V.; Mauro, A.E.; Ferreira, A.M.C.; Lopes, E.O.; Raddi, M.S.G.; Bauab, T.M.; Pavan, F.R.; Chorilli, M. A Nanostructured Lipid System as a Strategy to Improve the in Vitro Antibacterial Activity of Copper(II) Complexes. Molecules 2015, 20, 22534-22545.
da Silva PB, Bonifácio BV, Frem RCG, Godoy Netto AV, Mauro AE, Ferreira AMC, Lopes EO, Raddi MSG, Bauab TM, Pavan FR, Chorilli M. A Nanostructured Lipid System as a Strategy to Improve the in Vitro Antibacterial Activity of Copper(II) Complexes. Molecules. 2015; 20(12):22534-22545.Chicago/Turabian Style
da Silva, Patricia B.; Bonifácio, Bruna V.; Frem, Regina C.G.; Godoy Netto, Adelino V.; Mauro, Antonio E.; Ferreira, Ana M.C.; Lopes, Erica O.; Raddi, Maria S.G.; Bauab, Tais M.; Pavan, Fernando R.; Chorilli, Marlus. 2015. "A Nanostructured Lipid System as a Strategy to Improve the in Vitro Antibacterial Activity of Copper(II) Complexes." Molecules 20, no. 12: 22534-22545.