Ditiocarbamates and nitric oxide

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Polyhedron 25 (2006) 3366–3378 www.elsevier.com/locate/poly

Studies of the interaction between bis(dithiocarbamato)copper(II) complexes with nitric oxide in aqueous solution and biological applications
´ Agostinho Cachapa a, Alfredo Mederos a,*, Pedro Gili a, Rita Hernandez-Molina a, a a b ´ ´ ´ ´ Sixto Domınguez , Erasmo Chinea , Matıas Lopez Rodrıguez , Marta Feliz c, c d Rosa Llusar ,Felipe Brito , Carlos M. Ruiz de Galarreta e, ´ Carlos Tarbraue e, German Gallardo e

´ ´ Departamento de Quımica Inorganica, Facultad de Farmacia, Universidad de La Laguna, 38200 La Laguna, Tenerife, Canary Islands, Spain b ´ ´ Instituto Universitario de Bioorganica ‘‘A. Gonzalez’’, Universidad de La Laguna, Tenerife, Canary Islands, Spain c ´ Departamento de Ciencias Experimentales, UniversitatJaime I, Castellon, Spain d ´ ´ Centro de Equilibrios en Solucion, Escuela de Quımica, Facultad de Ciencias, Universidad Central de Venezuela, Caracas, Venezuela e ´ ´ ´ Departamento de Bioquımica, Biologıa Molecular y Fisiologıa, Facultad de Medicina, Universidad de Las Palmas de Gran Canaria, Gran Canaria, Canary Islands, Spain Received 27 February 2006; accepted 12 June 2006 Available online16 June 2006

Abstract Three new bis(dithiocarbamato)copper(II) complexes have been prepared and characterized by elemental analysis, UV–Vis, and IR spectroscopy: bis(4-piperidonedithiocarbamato)copper(II), [Cu(Pdtc)2]2 (1), bis(piperidinedithiocarbamato)copper(II), [Cu(Ppdtc)2]2 (2), and bis[(2-piperidinecarboxy)dithiocarbamato]copper(II), Cu(Ppidtc)2 (3). The crystal structures of the complexes1 and 2 have been determined using X-ray diffraction methods and they are dimeric. The coordination sphere of copper(II) ions is described as a distorted ˚ ˚ square-pyramid: the axial Cu–S bond distances 2.7 and 2.8 A for 1 and 2, respectively, are longer than the equatorial Cu–S ones (2.3 A). Complexes 1 and 2 are not soluble in water. In contrast, 3 is water soluble. The interaction of 3, thepreviously prepared bis[N-(dithiocarboxy)sarcosine]copper(II), Cu(Sdtc)2 (4), and bis[(dicarboxymethyl)dithiocarbamato]copper(II), Cu(Idadtc)2 (5), with nitric oxide in aqueous solution at pH 7.4 and 20 °C was spectrophotometrically studied and the experimental data were analysed by means of the SPEFO-LETAGROP and HYPERQUAD programs, respectively. The stability constants of the complexes CuL2(NO)and CuL2(NO)2 [L = dithiocarbamate] were determined. The interaction of 1 and 2 with nitric oxide was theoretically studied by molecular mechanics methods. Complexes 3, 4 and 5 and the previously studied bis[(dihydroxyethyl)dithiocarbamato]copper(II), Cu(Deadtc)2 (6), decrease the NO produced in vitro either by sodium nitroprusside (NPS) or by cultured murine macrophages J774 stimulated withlipopolysaccharide (LPS) and interferon-c (IFNc). Inducible nitric oxide synthase (iNOS) activity was determined by measuring the stable NO end product, nitrite, using a colorimetric assay. Ó 2006 Elsevier Ltd. All rights reserved.
Keywords: Copper(II) dithiocarbamates; Nitric oxide; Stability constants; Speciation; Murine macrophages

1. Introduction Nitric oxide is the simplest thermally stable freeradical molecule known [1,2]. This molecule is synthesized in vivo in mammalian cells and it acts as a short-lived intercellular messenger in important physiological processes [1–3]. In


Corresponding author. Tel.: +34 922318457; fax: +34 922318461. E-mail address: amederos@ull.es (A. Mederos).

0277-5387/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.doi:10.1016/j.poly.2006.06.008

A. Cachapa et al. / Polyhedron 25 (2006) 3366–3378


addition to regulate smooth muscle relaxation, neurotransmission, and immune response alterations in NO production and metabolism. The NO participates in multiple pathological circumstances such as hypertension, cardiomyopathy, pulmonary disorders, arteriosclerosis and endotoxemia [4–6]. Three different heme-containing...
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