Synthesis and Antileishmanial Activity of Lipidic Amino Alcohols

Chem Biol Drug Des 2010; 75: 233–235 ª 2009 John Wiley & Sons A/S doi: 10.1111/j.1747-0285.2009.00923.x Research Letter Synthesis and Antileishmanial Activity of Lipidic Amino Alcohols Elaine S. Coimbra1, Mauro V. de Almeida2, Celso O. R. Júnior2, Aline F. Taveira2, Cristiane F. da Costa2, Ana C. de Almeida1, Elaine F. C. Reis2 and Adilson D. da Silva2,* bition of L. amazonensis with IC50 below 10 lM. Compound 11f was more active than the reference drug amphotericin B against L. chagasi promastigote forms. Key words: amino alcohols, antileishmanial activity, lipophilicity 1 Departamento de Parasitologia, Microbiologia e Imunologia, Instituto de CiÞncias Biolgicas, Universidade Federal de Juiz de Fora, Cidade Universitria, 36036-900 Juiz de Fora, MG, Brazil 2 Departamento de Qumica, Instituto de CiÞncias Exatas, Universidade Federal de Juiz de Fora, Cidade Universitria, 36036900 Juiz de Fora, MG, Brazil *Corresponding author: Adilson D. da Silva, [email protected] Received 4 December 2008, revised 25 September 2009 and accepted for publication 1 November 2009 Leishmaniasis is a complex infection caused by multiple species of the intracellular protozoan parasite Leishmania. This disease is endemic in some tropical areas of the world and affects an estimated 12 million people with 2 million new cases annually (1,2). The clinical spectrum of leishmaniasis is varied and encompasses subclinical (inapparent), localized (skin lesions) and disseminated infection (cutaneous, mucosal or visceral) (2). Visceral manifestation is the more severe form of leishmaniasis, because it is fatal if In this work, a number of lipidic amino alcohols wereas synthesized and evaluated in vitro on cultures of Leishmania amazonensis and Leishmania chagasi. Nine amino alcohols showed inhibition of L. chagasi growth, and seven of them showed inhi- R2 H3C (CH2)n OH a H3C OMs (CH2)n R2 OH (CH2)n b N H3C (CH2)m R1 2a n = 7 2b n = 9 2c n = 11 2d n = 13 2e n = 15 1a n = 7 1b n = 9 1c n = 11 1d n = 13 1e n = 15 3a n = 7; R1=R2=H; m=1 4a n = 9; R1=R2=H; m=1 5a n = 11; R1=R2=H; m=1 5b n = 11; R1=H; R2=CH3; m=1 5c n = 11; R1=2-hydroxyethyl; R2=H; m=1 5d n = 11; R1=R2=H; m=2 6a n = 13; R1=R2=H; m=1 6b n = 13; R1=H; R2=CH3; m=1 6c n = 13; R1=2-hydroxyethyl; R2=H; m=1 6d n = 13; R1=R2=H; m=2 7a n = 15; R1=R2=H; m=1 OH OH OH H3C a H3C OMs (CH2)n (CH2)n b 9a n = 9 9b n = 11 8a n = 9 8b n = 11 c, d OH H3C R1 N R2 (CH2)n OH H3C NH2 (CH2)n 10a n =9 10b n =11 11a n = 9; R1=H; R2=2-hydroxyethyl 11b n = 9; R1=H; R2=3-hydroxypropyl 11c n = 9; R1=R2=2-hydroxyethyl 11d n = 9; R1=H; R2=1,1-dimethyl-2-hydroxyethyl 11e n = 9; R1=H; R2=2-aminoethyl 11f n = 9; R1=H; R2=3-aminopropyl 12a n = 11; R1=H; R2=2-hydroxyethyl 12b n = 11; R1=H; R2=3-hydroxypropyl 12c n = 11; R1=R2=2-hydroxyethyl 12d n = 11; R1=H; R2=1,1-dimethyl-2-hydroxyethyl Scheme 1: Synthesis of lipidic amino alcohols. (a) MsCl, CH2Cl2, Py, 0 C to room temperature; (b) amino alcohol or diamine, EtOH reflux; (c) NaN3, DMF; (d) H2, Pd ⁄ C, EtOH, room temperature. 233 Coimbra et al. Table 1: Values of IC50 (lM) for the activity of the compounds against Leishmania amazonensis and Leishmania chagasi promastigote forms Compound L. amazonensis L. chagasi 3a 4a 5a 5b 5c 5d 6a 6b 6c 6d 7a 10a 10b 11a 11b 11c 11d 11e 11f 12a 12b 12c 12d Amphotericin B (reference drug) 76.38 (€2.79) 11.74 (€0.50) 8.57 (€1.90) >227 14.82 (€0.10) 25.14 (€0.20) Nd >227 4.90 (€0.06) >227 16.92 (€1.62) 26.00 (€1.20) Nd 11.78 (€0.53) 5.09 (€0.33) 9.16 (€0.59) 12.30 (€0.10) 2.82 (€0.11) 4.09 (€0.34) Nd >227 8.07 (€0.11) >227 0.90 (€0.07) 9.65 (€0.015) 5.50 (€0.35) 5.42 (€0.96) 119.56 (€12.97) 4.90 (€0.07) 3.20 (€0.20) Nd >227 9.22 (€0.93) >227 19.60 (€2.34) 14.58 (€0.91) Nd 2.17 (€0.05) Nd 11.28 (€0.10) 16.38 (€0.59) Nd 1.26 (€0.08) Nd 7.70 (€0.03) 16.40 (€1.37) 45.60 (€0.94) 1.90 (€0.25) Nd, not determined. untreated (2,3). There is so far no vaccine approved for clinical use. Chemotherapy of all leishmaniasis manifestations has been based on the pentavalent antimonials such as sodium stibogluconate (pentostam) and meglumine antimoniate (glucantime), since their discovery in 1940s (4–6). These drugs induce toxic side effects and require lengthy treatments with parenteral administration (4,5). Strains of Leishmania donovani resistant to antimonials are frequent in India, where most of the cases are not responsive to these drugs (5). The inefficacy of the treatment with antimonials is particularly elevated in the HIV–Leishmania co-infection, where therapeutical effectiveness is diminished during relapses (4,5). Pentamidine, amphotericin B and paromomycin are used as a second option in resistant cases, despite their great toxicity to the host (2,6). New alternative leishmaniasis treatment have been developed, including colloidal and lipid formulations and recently the oral drug miltefosine (4–6). Nevertheless, all therapies have some limitations as several toxic effects and unaffordable cost (5,6). In a previous study, we have shown that lipophilic diamine derivatives have proved inhibitory effects in Leishmania (7,8). So, the aim of this study was to evaluate in vitro some lipidic amino alcohols against different species of Leishmania. These types of compounds can interact with membrane lipids and possibly, to interfere with the lipid or polyamine transport or metabolism of the parasite (9–14). In this context, we describe in this work the synthesis of several Nalkyl amino alcohols and their antileishmanial evaluation. Amino alcohols were prepared using a similar methodology previously described (Scheme 1) (8,15–18). Alcohols 1a–e (octanol, decanol, 234 dodecanol, tetradecanol and hexadecanol) were first treated with methanesulfonyl chloride in methylene chloride and pyridine to furnish the corresponding mesylates 2a–e. The crude mesylates were treated with amino alcohols (2-amino-ethanol, 3-amino-1-propanol, diethanolamine and 2-amino-2-methy-1-propanol) in ethanol at reflux to furnish the desired compounds 3a, 4a, 5a–d, 6a–d and 7a in 50–90% yield in two steps. For the preparation of the lipophilic compounds 10a and 10b, mesylated derivative 9a and 9b were treated with sodium azide in dimethylformamide (DMF) at 120 C, leading to the corresponding azides in quantitative yield. These azides were hydrogenated in presence of palladium on charcoal 10% in ethanol, furnishing amino alcohols 10a and 10b in 74% and 76% yield, respectively. Amino alcohols 11a–f and 12a– d were obtained in a similar way from 1,2-dodecanediol and 1,2-tetradecanediol by treatment of mesylates 9a and 9b with four amino alcohols and two diamines (1,2-diaminoethane and 1,3-diaminopropane) (Scheme 1). All compounds were characterized by 1H NMR and 13C NMR spectroscopy. Leishmania amazonensis (MHOM ⁄ Br ⁄ 75 ⁄ Josefa isolated from a patient with diffuse cutaneous leishmaniasis) and Leishmania chagasi (MHOM ⁄ Br ⁄ 74 ⁄ PP75 isolated from a patient with visceral leishmaniasis) promastigotes were used for in vitro screening. The antiproliferative activity of compounds was determined by colorimetric 3-(4,5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) method based on tetrazolium salt reduction by mitochondrial dehydrogenases, as previously described (8,14). The results are expressed as the concentrations inhibiting parasite growth by 50% (IC50) after a 3-day incubation period. The IC50 values represent means of three separate experiments. Amphotericin B was used as the reference drug. As observed in Table 1, the diamine alcohol derivative 11f displayed the best antiproliferative activity against L. chagasi promastigote forms (IC50 = 1.26 lM), being more active than the reference drug amphotericin B. In this series, compounds 5a, 6c, 11b, 11c, 11e and 12c (against L. amazonensis) and compounds 3a, 4a, 5a, 5c, 5d, 6c, 11a and 12b (against L. chagasi) displayed good in vitro activity (IC50 below 10 lM). Ramified amino alcohols 5b, 6b and 12d showed little activity. Importantly, compounds containing alkyl chains with 10 and 12 carbon atoms showed better activity against both species of Leishmania promastigotes. In summary, this work describes the synthesis and antileishmanial evaluation of several lipidic amino alcohols derivatives. The results showed here, together with previously published data, provided evidence that the N-alkyl lipophilic diamines and amino alcohols could be prototypes for new antileishmanial drugs. Further studies in vitro and in vivo are required to assess its biological activity in order to better understand its mechanism of action and pharmacological effects. Acknowledgments The authors gratefully acknowledge UFJF, CAPES and CNPq for fellowships. 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