In vitro and in vivo anti-inflammatory active copper(II)-lawsone complexes

We report in vitro and in vivo anti-inflammatory activities of a series of copper(II)-lawsone complexes of the general composition [Cu(Law)(2)(L(N))(x)(H(2)O)((2-x))]·yH(2)O; where HLaw = 2-hydroxy-1,4-naphthoquinone, x = 1 when L(N) = pyridine (1) and 2-aminopyridine (3) and x = 2 when L(N) = imidazole (2), 3-aminopyridine (4), 4-aminopyridine (5), 3-hydroxypyridine (6), and 3,5-dimethylpyrazole (7). The compounds were thoroughly characterized by physical techniques, including single crystal X-ray analysis of complex 2. Some of the complexes showed the ability to suppress significantly the activation of nuclear factor κB (NF-κB) both by lipopolysaccharide (LPS) and TNF-alpha (complexes 3–7 at 100 nM level) in the similar manner as the reference drug prednisone (at 1 μM level). On the other hand, all the complexes 1–7 decreased significantly the levels of the secreted TNF-alpha after the LPS activation of THP-1 cells, thus showing the anti-inflammatory potential via both NF-κB moderation and by other mechanisms, such as influence on TNF-alpha transcription and/or translation and/or secretion. In addition, a strong intracellular pro-oxidative effect of all the complexes has been found at 100 nM dose in vitro. The ability to suppress the inflammatory response, caused by the subcutaneous application of λ-carrageenan, has been determined by in vivo testing in hind-paw edema model on rats. The most active complexes 1–3 (applied in a dose corresponding to 40 μmol Cu/kg), diminished the formation of edema simalarly as the reference drug indomethacine (applied in 10 mg/kg dose). The overall effect of the complexes, dominantly 1–3, shows similarity to anti-inflammatory drug benoxaprofen, known to induce intracellular pro-oxidative effects.