Synthesis and cytotoxic activity of various 5-[alkoxy-(4-nitro-phenyl)-methyl]-uracils in their racemic form Lucie Spa ´c ˇilova ´, a,  Petr Dz ˇuba ´k, b,  Maria ´n Hajdu ´ch, b Son ˇa Kr ˇupkova ´, a Pavel Hradil a and Jan Hlava ´c ˇ a, * a Department of Organic Chemistry, Faculty of Science, Palacky ´ University, Tr ˇ. Svobody 8, 771 46 Olomouc, Czech Republic b Laboratory of Experimental Medicine, Departments of Pediatrics and Oncology, Faculty of Medicine, Palacky ´ University and Faculty Hospital in Olomouc, Pus ˇkinova 6, 775 20 Olomouc, Czech Republic Received 17 July 2007; revised 31 August 2007; accepted 5 September 2007 Available online 8 September 2007 Abstract—The preparation of various 5-[alkoxy-(4-nitro-phenyl)-methyl]-uracils with alkyl chain lengths C 1 –C 12 is described. The synthesis is based on the preparation of 5-[chloro-(4-nitro-phenyl)-methyl]-uracil and subsequent substitution of chlorine with appropriate alcohols. The resulting ethers were tested for their cytotoxic activity in vitro against five cancer cell lines. The com- pounds were less active in lung resistance protein expressing cell lines, suggesting the involvement of this multidrug resistant protein in control of the biological activity. Cytotoxic substances induced rapid inhibition of DNA and modulation of RNA synthesis followed by induction of apoptosis. The data indicate that the biological activity of 5-[alkoxy-(4-nitro-phenyl)-methyl]-uracils depends on the alkyl chain length. Ó 2007 Elsevier Ltd. All rights reserved. Compounds derived from 5-alkyluracil are well known for their biological activity. Some of them, for exam- ple, have been described as suitable agents for treating various diseases caused by excessive cell proliferation, such as in the treatment of various cancers 1 or treat- ment of proliferative diseases mediated by second mes- sengers. 2 The most potent 5-alkyluracils inhibited the proliferation of leukemia, lymphoma, and solid tu- mor-derived cell lines at micromolar concentrations. 3 Our research is focused on derivatives of 5-alkoxyura- cils with anticancer activity. In this paper we describe the synthesis and cytotoxic activity of 5-[alkoxy-(4-ni- tro-phenyl)-methyl]-uracils having various alkyl chain lengths. The reaction of uracil with benzaldehyde is reported to afford the appropriate derivative 2. 4 If 4-nitrobenzalde- hyde is used instead, 5-[hydroxy-(4-nitro-phenyl)- methyl]-uracil 6 results as is described in the same pub- lication (Scheme 1). In our hands the reaction does not lead to compound 6, but rather to a mixture of 5-[chloro-(4-nitro-phenyl)- methyl]-uracil 3 and 5,5 0 -(4-nitrophenyl)-methyl-bis- 1H-pyrimidine-2,4-dione 4 instead. We successfully tried to find reaction conditions for selective preparation of each derivative (Scheme 2). Derivative 4 has been prepared recently by nitration of 5,5 0 -phenylmethylene-bis-uracil and patented in the class of anti-ictogenic or anti-epileptogenic agents. 5 0960-894X/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.bmcl.2007.09.022 Keywords: Uracil; DNA; RNA; Apoptosis; Cytotoxic; Anticancer activity. * Corresponding author. Tel./fax: +420 585634405; e-mail addresses: hajduchm@gmail.com; hlavac@prfnw.upol.cz   These authors contributed equally to the work. Scheme 1. Reaction of uracil with benzaldehyde and p-nitrobenzalde- hyde according to Ref. 4. Available online at www.sciencedirect.com Bioorganic & Medicinal Chemistry Letters 17 (2007) 6647–6650