Original article Synthesis and evaluation of N-acylamino acids derivatives of triazenes. Activation by tyrosinase in human melanoma cell lines Ana Sofia Monteiro a , Joana Almeida a , Guadalupe Cabral b, c , Paulo Severino b , Paula A. Videira b , Ana Sousa a , Rafael Nunes a , João D. Pereira a , Ana Paula Francisco a , M. Jesus Perry a , Eduarda Mendes a, * a Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal b CEDOC, Immunology Department, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Campo Mártires da Pátria 130,1169-056 Lisboa, Portugal c Universidade Lusófona de Humanidades e Tecnologias, ULHT Lisboa, Campo Grande 376,1749-024 Lisboa, Portugal article info Article history: Received 17 April 2013 Received in revised form 17 September 2013 Accepted 20 September 2013 Available online 2 October 2013 Keywords: Prodrugs Triazenes Tyrosinase Melanoma cells abstract In this research work we report the synthesis of a new series of triazene prodrugs designed for Melanocyte-Directed Enzyme Prodrug Therapy (MDEPT). These compounds are derived from the N- acyltyrosine amino acid e a good enzyme substrate for the tyrosinase enzyme, which is significantly overexpressed in melanoma cells. We analysed their chemical stability and plasma enzymatic hydrolysis, and we also evaluated the release of the antitumoral drug in the presence of the tyrosinase. Subse- quently, we performed the evaluation of the prodrug cytotoxicity in melanoma cell lines with different levels of tyrosinase activity. Prodrug 5c showed the highest cytotoxicity against melanoma cell lines, and this effect correlated well with the tyrosinase activity suggesting that prodrug cytotoxicity is tyrosinase- dependent. Ó 2013 Elsevier Masson SAS. All rights reserved. 1. Introduction Disseminated melanoma is a highly metastatic malignancy which is generally lethal. Systemic chemotherapy is often the only recourse, but to date the results have been very disappointing and the lack of selective cytotoxicity often leads to intolerable side ef- fects. Triazenes are a well-known class of anticancer drugs used in the treatment of melanoma, which have a N]NeN structure type generally close to an aromatic ring. Dacarbazine (DTIC) (1) and Temozolomide (2) are the only triazenes in current chemotherapy [1,2]. The mechanism of their antitumour activity works via the alkylation of the DNA, through in vivo generation of methyl- diazonium cations. Both temozolomide and DTIC are prodrugs of the active alkylating agent 5-(3-methyltriazen-1-yl)imidazole-4- carboximide e MTIC (3). Unlike DTIC, which requires metabolic activation by cytochrome P450, temozolomide spontaneously converts to 3 under physiologic conditions [3e7]. 1 2 3 * Corresponding author. Tel.: þ351 217946413; fax: þ351 217946470. E-mail address: ermendes@ff.ul.pt (E. Mendes). Contents lists available at ScienceDirect European Journal of Medicinal Chemistry journal homepage: http://www.elsevier.com/locate/ejmech 0223-5234/$ e see front matter Ó 2013 Elsevier Masson SAS. All rights reserved. http://dx.doi.org/10.1016/j.ejmech.2013.09.040 European Journal of Medicinal Chemistry 70 (2013) 1e9