Indolylarylsulfones Bearing Natural and Unnatural Amino Acids. Discovery of Potent Inhibitors of HIV-1 Non-Nucleoside Wild Type and Resistant Mutant Strains Reverse Transcriptase and Coxsackie B4 Virus Francesco Piscitelli, † Antonio Coluccia, | Andrea Brancale, | Giuseppe La Regina, † Anna Sansone, † Cesare Giordano, ⊥ Jan Balzarini, ∞ Giovanni Maga, ‡ Samantha Zanoli, ‡ Alberta Samuele, ‡ Roberto Cirilli, # Francesco La Torre, # Antonio Lavecchia, § Ettore Novellino, § and Romano Silvestri* ,† Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza UniVersita ` di Roma, Piazzale Aldo Moro 5, I-00185 Roma, Italy, Welsh School of Pharmacy, Cardiff UniVersity, King Edward VII AVenue, Cardiff, CF10 3NB, U.K., Istituto di Chimica Biomolecolare del CNR, Sapienza UniVersita ` di Roma, Piazzale Aldo Moro 5, I-00185 Roma, Italy, Dipartimento di Chimica Farmaceutica e Tossicologica, UniVersita ` di Napoli Federico II, Via Domenico Montesano 49, I-80131, Napoli, Italy, Rega Institute for Medical Research, Katholieke UniVersiteit LeuVen, B-3000 LeuVen, Belgium, Istituto di Genetica Molecolare-Consiglio Nazionale delle Ricerche, Via Abbiategrasso 207, I-27100 PaVia, Italy, and Dipartimento del Farmaco, Istituto Superiore di Sanità, Viale Regina Elena 299, I-00161 Roma, Italy ReceiVed NoVember 21, 2008 New potent indolylarylsulfone (IAS) HIV-1 NNRTIs were obtained by coupling natural and unnatural amino acids to the 2-carboxamide and introducing different electron-withdrawing substituents at position 4 and 5 of the indole nucleus. The new IASs inhibited the HIV-1 replication in human T-lymphocyte (CEM) cells at low/subnanomolar concentration and were weakly cytostatic. Against the mutant L100I, K103N, and Y181C RT HIV-1 strains in CEM cells, sulfones 3, 4, 19, 27, and 31 were comparable to EFV. The new IASs were inhibitors to Coxsackie B4 virus at low micromolar (2-9 µM) concentrations. Superimposition of PLANTS docked conformations of IASs 19 and 9 revealed different hydrophobic interactions of the 3,5-dimethylphenyl group, for which a staking interaction with Tyr181 aromatic side chain was observed. The binding mode of 19 was not affected by the L100I mutation and was consistent with the interactions reported for the WT strain. Introduction Acquired immunodeficiency syndrome (AIDS a ) causes over 5700 deaths every year, and at the same time over 6800 people become infected with human immunodeficiency virus (HIV). 1 Both prevention and treatment of HIV are still inadequate. The challenge toward new anti-HIV/AIDS drugs is the discovery of (i) an effective vaccine, (ii) better tolerated drugs, and (iii) agents endowed with improved properties against both drug resistance and cross-resistance. 2 Drugs currently approved for the treatment of HIV infection fall into six target classes. In addition to (i) nucleoside (NRTIs) and nucleotide (NtRTIs) reverse transcriptase inhibitors, (ii) non- nucleoside reverse transcriptase inhibitors (NNRTIs), (iii) pro- tease inhibitors (PIs), and (iv) fusion inhibitors (FIs), 3 two new drugs, (v) the entry inhibitor CCR5 co-receptor antagonist maraviroc and (vi) the integrase inhibitor raltegravir, became available in 2007. 4 These drugs slow the viral infection and multiplication, affecting the progression of the disease. By combination of three (recommended) or four antiretroviral drugs, highly active antiretroviral therapy (HAART) produces an effective and prolonged reduction of morbidity and mortality in AIDS patients. 5 However, HAART does not completely eradicate the viral infection; thus, the required long-term drug administrations provoke drug resistance and unwanted side effects. 6 NNRTIs showed low toxicity and favorable pharmacokinetic properties. The major problem of earlier inhibitors, namely, the rapid emergence of drug resistance, was overcome by new generation agents that succeeded in inhibiting both HIV-1 wild type (WT) and viral strains carrying NNRTI resistance muta- tions. 7 Etravirine was approved in 2008 by the U.S. FDA for the drug combination treatment of HIV-1 infected people who experienced drug resistance to other drugs of this class. 8 The development of indolylarylsulfones (IASs) NNRTIs was based on the Merck derivative L-737,126 (1) 9 as reference compound. The potent activity of IAS 2 against the NNRTI- resistant mutants was correlated to the presence of a 3-(3,5- dimethylphenyl)sulfonyl moiety. 10 Potent IAS derivatives were obtained by adding to the 2-carboxamide chain of 2 simple amino acids such as glycine and D,L-alanine to give derivatives (for example, 3 and 4) endowed with activities against HIV-1 WT and NNRTI-resistant mutants superior to that of the parent indole 1. 11 On the other hand, the activity against the K103N RT mutant virus exhibited by imidazole 5 12 prompted the synthesis of derivatives bearing either the N-(2-hydroxyethyl)carboxamide functionality (6) 13 or substituted N′-carboxyhydrazide derivatives (7) 14 at position 2 of the indole. DuPont Merck synthesized analogues of efavirenz (8) containing two halogen atoms at positions 5 and 6 of the quinazolinone ring which showed * To whom correspondence should be addressed. Phone: +39 06 4991 3800. Fax: +39 06 491 491. E-mail: romano.silvestri@uniroma1.it. † Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Universita ` di Roma. | Cardiff University. ⊥ Consiglio Nazionale delle Ricerche, Roma. ∞ Katholieke Universiteit Leuven. ‡ Consiglio Nazionale delle Ricerche, Pavia. # Istituto Superiore di Sanità, Roma. § Universita ` di Napoli Federico II. a Abbreviations, IAS, indolylarylsulfone; HIV, human immunodeficiency virus; AIDS, acquired immunodeficiency syndrome; RT, reverse tran- scriptase; NRTI, nucleoside/nucleotide reverse transcriptase inhibitor; NNRTI, non-nucleoside reverse transcriptase inhibitor; PI, protease inhibitor; FI, fusion inhibitor; HAART, highly active antiretroviral therapy; WT, wild type; NVP, nevirapine; EFV, efavirenz. J. Med. Chem. 2009, 52, 1922–1934 1922 10.1021/jm801470b CCC: $40.75  2009 American Chemical Society Published on Web 03/12/2009