Chem Biol Drug Des 2014; 83: 126–131 Research Letter Mefloquine–Oxazolidine Derivatives: A New Class of Anticancer Agents Felipe A. R. Rodrigues1, Igor da S. Bomfim1, applications in other fields, such as against Gram-positive Bruno C. Cavalcanti1, Claudia Pessoa1, Raoni and Gram-negative bacteria (1), in particular against Myco- S. B. Goncalves2, James L. Wardell2,3, Solange bacterium tuberculosis (2,3) and Mycobacterium avium M. S. V. Wardell4 and Marcus V. N. de Souza2,* complex (MAC) (4,5) and also against schistosomiasis (6), neurodegenerative, and (neuro-) inflammatory diseases (7). 1Laboratorio de Oncologia Experimental, Universidade A clear indication of the promise of this drug in fields other Federal do Ceara, Fortaleza, CE 3157, Brazil than malaria is the number of recent patent applications 2FioCruz-Fundacßao~ Oswaldo Cruz, Instituto de Tecnologia (5,7,8). More recently, much attention has been paid to the em Farmacos-Far-Manguinhos, Rua Sizenando Nabuco, potential perspectives of MQ as an anticancer agent. As 100, Manguinhos, 21041-250, Rio de Janeiro, RJ 35513, estimated by the National Institutes of Health (NIH), the over- Brazil all costs of cancer in 2007 were $226.8 billion.a Cancer is a 3Department of Chemistry, University of Aberdeen, Old leading cause of deaths worldwide and accounted for 7.6 Aberdeem, Aberdeem, AB 24 3UE, UK b 4CHEMSOL, 1 Harcourt Road, Aberdeen, AB15 5NY, UK million deaths (13% of all deaths) in 2008. Louie and *Corresponding author: Marcus V. N. de Souza, coworkers (9) found MQ to be the most potent anticancer marcos_souza@far.fiocruz.br drug when compared to chloroquine and the fluoroquino- lone drugs cipro and levofloxacin. MQ inhibits autophagy A series of 23 racemic mefloquine–oxazolidine deriva- and triggered endoplasmic reticulum stress. It also causes tives, 4-[3-(aryl)hexahydro[1,3]oxazolo[3,4-a]pyridin- cell death in T47D and MDAMB-231. Cho and coworkers 1-yl]-2,8-bis(trifluoromethyl)quinolines, derived from also investigated the effect of autophagy on mefloquine- (R*, S*)-(±)-mefloquine and arenealdehydes, have been mediated cytotoxicity in neuroblastoma cells (10). evaluated for their activity against four cancer cell lines (HCT-8, OVCAR-8, HL-60, and SF-295). Good cytotox- To study the potential of MQ analogues as anticancer icities have been determined with IC values ranging 50 agents, it is necessary to develop and evaluate MQ deriva- from 0.59 to 4.79 lg/mL. In general compounds with tives. Prime goals are to enhance the effectiveness and to aryl groups having strong electron-releasing substitu- ents, such as HO and MeO, or electron-rich heteroaryl minimize side-effects, as well as to provide a better under- groups, for example imidazol-2-y-l, are active. How- standing of the mechanism of action. In this work, we ever, other factors such as steric effects may play a present the results of the evaluation of a series of twenty- role. As both the active and non-active conformations three mefloquine–oxazolidine derivatives (Scheme 1) of the mefloquine–oxazolidine derivatives are similar, it against several cancer cell lines, including HCT-8, is concluded that molecular conformations do not play OVCAR-8, HL-60 and SF-295. The results are very prom- a significant role either. This study is the first to evalu- ising, as exemplified in Tables 1 and 2. ate mefloquine derivatives as antitumor agents. The mefloquine–oxazolidine derivatives are considered to be useful leads for the rational design of new antitumor agents. Methods and Materials Key words: anticancer, antitumor activity, mefloquine, Cytotoxicity assays oxazolidine Cytotoxicity against cancer cell lines Received 15 April 2013, revised 16 June 2013 and accepted Compounds 1a–s, 2a–c, 3 and MQ (0.009–5 lg/mL) were for publication 12 August 2013 tested for their cytotoxic activity against 3–5 cancer cell lines: SF-295 (nervous system), HCT-116 (colon), OVCAR- 8 (ovarium), HCT-8 (colon), and HL60 (leukemia) (National Mefloquine (MQ), (R*,S*)-(Æ)-a-2-piperidinyl-2,8-bis(trifluo- Cancer Institute, Bethesda, MD, USA). All cell lines were romethyl)-4-quinolinemethanol, also known as Lariam, maintained in RPMI 1640 medium supplemented with 10% Mephaquin, or Mefliam, is an important drug orally adminis- fetal bovine serum, 2 mM glutamine, 100 U/mL penicillin, trated in the prevention and treatment of malaria. However, and 100 lg/mL streptomycin at 37 °C with 5% CO2. Each in the last years, this drug has been found to have promising compound was dissolved in DMSO to give a concentration 126 ª 2013 John Wiley & Sons A/S. doi: 10.1111/cbdd.12210 Mefloquine Derivatives as New Class of Anticancer Agents R Y Ar X N HN R Y N O HO X O ArCHO CHO N CF3 N CF3 N CF3 CF3 CF3 CF3 1 Mefloquine 2 OHC CHO F3C N F3C O N N O CF3 3 N Scheme 1: Synthesis of mefloquine–oxazolidine derivatives. CF3 Table 1: Growth inhibition percentage (GI%) for three tumor cell linesa, measured by MTT assay Entry SF-295 HCT-116 OVCAR-8 No Ar or heteroaryl GI%SD% GI%SD% GI% SD% 1a C6H5 33.74 0.46 56.74 3.85 43.52 4.33 1b 2-HOC6H4 100.88 0.06 100.82 0.27 101.44 0.00 1c 2-MeOC6H4 53.80 1.90 94.81 3.04 100.78 0.31 1d 4-MeOC6H4 31.84 8.89 71.09 2.06 21.68 14.34 1e 3,4-(MeO)2C6H3 46.55 9.45 100.30 0.85 100.29 0.58 1f 3,4,5-(MeO)3C6H2 36.80 5.71 52.78 5.94 21.55 1.23 1g 3-EtOC6H4 34.69 8.06 24.40 59.49 8.99 13.64 1h 4-FC6H4 32.89 0.77 39.78 0.18 31.33 1.65 1i 2-ClC6H4 22.28 0.59 40.09 38.92 12.26 4.78 1j 3-ClC6H4 33.50 6.73 27.84 13.76 26.20 3.56 1k 4-ClC6H4 80.38 28.93 101.58 0.45 101.16 0.08 1l 2,3-Cl-2C6H3 24.94 3.10 40.28 3.41 8.50 0.41 1m 2,4-Cl2C6H3 17.41 8.42 19.70 1.39 À17.58 7.63 1n 3,4-Cl2C6H3 20.39 14.64 23.58 1.43 12.04 2.74 1o 3-BrC6H4 34.50 4.56 42.02 3.95 36.17 12.52 1p 4-BrC6H4 38.13 9.01 53.95 0.18 20.85 7.68 1q 2-O2NC6H4 22.56 22.32 23.77 48.30 23.56 3.48 1r 3-O2NC6H4 30.89 1.74 32.29 0.43 11.96 17.24 1s 4-O2NC6H4 29.12 21.72 61.47 2.24 18.70 2.74 2a 5-O2N-furan-2-yl 37.80 4.45 14.42 0.32 10.38 23.13 2b 5-O2N-thien-2-yl 14.14 3.86 18.99 6.64 26.41 4.99 2c Imidazol-2-yl 29.91 3.68 84.82 12.70 97.51 0.08 3 – 37.11 5.00 À0.66 4.37 À6.62 0.25 – Mefloquine 98.44 2.42 101.93 1.36 99.93 0.46 aCell lines: nervous system (SF-295), colon (HCT-116), and ovarium (OVCAR-8). of 1 mg/mL. The final concentration of DMSO in the culture (0.001% in the highest concentration). The cell viability was medium was kept below 0.1% (v/v). Compounds 1a–s, determined by reduction in the yellow dye 3-(4,5-dimethyl- 2a–c, 3, and MQ were incubated with the cells for 72 h. 2-thiazol)-2,5-diphenyl-2H-tetrazolium bromide (MTT) to a The negative control received the same amount of DMSO blue formazan product as described by Mosmann (11). Chem Biol Drug Des 2014; 83: 126–131 127 Rodrigues et al. Table 2: Cytotoxic activity of mefloquine–oxazolidine derivatives 1b–e and 2 on Tumor Cell Linesa Entry IC50 (lg/mL) No Ar or heteroaryl HCT-8 OVCAR-8 HL-60 SF-295 1b 2-HOC6H4 2.699 2.824 3.338 1.606 2.320–3.140 2.346–3.400 2.186–5.098 0.9841–2.621 1c 2-MeOC6H4 2.957 4.074 3.635 4.785 2.657–3.291 3.304–5.023 2.606–5.070 2.833–8.082 1d 4-MeOC6H4 1.514 0.9450 1.913 3.598 1.251–1.831 0.5600–1.595 1.498–2.444 3.299–3.925 1e 3,4-(MeO)2C6H3 3.077 2.839 2.343 3.250 2.359–4.012 1.041–7.738 2.101–2.613 2.519–4.194 1k 4-Cl C6H4 2.957 4.074 0.8873 3.524 2.658–3.291 3.304–5.023 0.4072–1.934 3.049–4.072 2c Imidazol-2-yl 1.732 3.297 0.5916 3.524 1.404–2.137 2.318–4.688 0.3341–1.047 3.049–4.072 Mefloquine 1.385 2.834 0.8176 2.831 1.233–1.556 2.156–3.726 0.3970–1.684 1.781–4.500 Doxorubicin 0.01 0.265 0.02 0.23 0.01–0.02 (0.17–0.305) 0.01–0.02 0.19–0.25 a Data are presented as IC50 values, with 95% confidence intervals obtained by nonlinear regression for all cell lines leukemia (HL-60), ovar- ium (OVCAR-8), nervous system (SF-295), colon (HCT-8) from three independent experiments.