1-Methyl and 1-(2-hydroxyalkyl)-5-(3-alkyl/cycloalkyl/phenyl/naphthylureido)- 1H-pyrazole-4-carboxylic acid ethyl esters as potent human neutrophil chemotaxis inhibitors Olga Bruno a, * , Chiara Brullo a , Francesco Bondavalli a , Silvia Schenone a , Susanna Spisani b , Maria Sofia Falzarano b , Katia Varani c , Elisabetta Barocelli d , Vigilio Ballabeni d , Carmine Giorgio d , Massimiliano Tognolini d a Dipartimento di Scienze Farmaceutiche, Università di Genova, Viale Benedetto XV, 3, 16132 Genova, Italy b Dipartimento di Biochimica e Biologia Molecolare, Università degli Studi di Ferrara, via Luigi Borsari, 46, 44100 Ferrara, Italy c Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Ferrara, via Fossato di Mortara 17/19, 44100 Ferrara, Italy d Dipartimento di Scienze Farmacologiche, Biologiche e Chimiche Applicate, Università degli Studi di Parma, V.le GP Usberti, 27/A, 43100 Parma, Italy article info Article history: Received 14 November 2008 Revised 13 March 2009 Accepted 20 March 2009 Available online 25 March 2009 Keywords: 1-(2-Hydroxyalkyl)-5-(3-alkyl/benzyl/- phenyl/naphthylureido)-1H-pyrazole-4- carboxylic acid ethyl esters Neutrophil chemotaxis inhibitors IL8/CXCL8 (Interleukin 8) fMLP-OMe N-Formyl-methionyl-leucyl-phenylalanine methyl ester Zymosan-induced peritonitis abstract In this paper we report the synthesis and the chemotaxis inhibitory activity of a number of 1H-pyrazole- 4-carboxylic acid ethyl esters 2 functionalized in N1 with a methyl group or different hydroxyalkyl chains and in position 5 with a series of 3-substituted urea groups. These compounds were designed as devel- opment of previous pyrazole-urea derivatives that resulted potent IL8-induced neutrophil chemotaxis inhibitors in vitro. Most of the new compounds revealed a potent inhibition of both IL8- and fMLP- OMe-stimulated neutrophil chemotaxis. The most active compounds in the fMLP-OMe induced chemo- taxis test showed IC 50 in the range 0.19 nM–2 lM; but we observed a very strong inhibition in the IL8-induced chemotaxis test, having the most active compounds IC 50 at pM concentrations. In vivo com- pounds 2e and 2f, although to a lesser extent, at 50 mg/kg os decreased granulocyte infiltration in zymo- san-induced peritonitis in mice. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Neutrophils are the main cells infiltrated in the course of acute inflammation. Their activation consists in subsequent events: mar- gination, diapedesis and migration (chemotaxis) to site of inflam- mation where they take part in the phagocytosis of foreign particles and reactive free radicals production. 1,2 Chemotaxis is a very complex multi-step process induced by various chemoattrac- tans as N-formyl-methionyl-leucyl-phenylalanine (fMLP), 3,4 plate- let activating factor (PAF), 5 leukotriene B4 (LTB4), 6 C5a anaphylotoxin, 7 and different chemokines such as the CC chemo- kine MIP 1b (macrophage inhibition factor), or the CXC chemokine interleukine 8 (IL8, also named CXCL8). 8 When the control of cellular recruitment breaks down, both acute and chronic autoimmune inflammatory disorders (e.g., asth- ma, rheumatoid arthritis, multiple sclerosis) will ensue. In the last years the search for new small molecules able to interfere with numerous and different mechanisms involved in neutrophil upregulation greatly engaged many medicinal chemis- try researchers. In this context, we recently reported many pyrazoles (com- pounds 1, Fig. 1) which resulted active as IL8-induced chemotaxis inhibitors in vitro. 9 These compounds, obtained by functionaliza- tion with a urea moiety of the 5-amino-1-(2-hydroxy-2-phenyl- ethyl)-1H-pyrazole-4-carboxylic acid ethyl ester, blocked the IL8- 0968-0896/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.bmc.2009.03.035 * Corresponding author. Tel.: +39 010 353 8367; fax: +39 010 353 8358. E-mail address: obruno@unige.it (O. Bruno). Figure 1. Chemical structure of compounds 1. Bioorganic & Medicinal Chemistry 17 (2009) 3379–3387 Contents lists available at ScienceDirect Bioorganic & Medicinal Chemistry journal homepage: www.elsevier.com/locate/bmc