Synthesis and biological activity against Trypanosoma cruzi of substituted 1,4-naphthoquinones

Article abstract of DOI:10.1016/j.ejmech.2012.11.034

The discovery and development of essential drugs for Chagas disease is a major concern worldwide. New substituted 1,4-naphthoquinones were synthesized and tested against the infective bloodstream form of Trypanosoma cruzi, the etiological agent of Chagas disease. These products exhibited substantial activity against T. cruzi, especially 2-((8E,11Z)-heptadeca-8,11-dienyl)-3- hydroxynaphthalene-1,4-dione (9) with IC₅₀ of 7.8 μM.

Full text of DOI:10.1016/j.ejmech.2012.11.034

European Journal of Medicinal Chemistry 60 (2013) 51e56
Contents lists available at SciVerse ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis and biological activity against Trypanosoma cruzi of substituted
1,4-naphthoquinones
Adriano Olímpio da Silva a, Rosangela da Silva Lopes a, Ricardo Vieira de Lima a,
Camila Santos Suniga Tozatti a, Maria Rita Marques b, Sérgio de Albuquerque c, Adilson Beatriz a,
,
Dênis Pires de Lima a
*
a Chemistry Sector (LP4), Center of Exact Sciences and Technology, Federal University of Mato Grosso do Sul, 79070-900 Campo Grande, MS, Brazil
b Center of Biological Sciences and Health, Federal University of Mato Grosso do Sul, Cidade Universitária s/n, 79070-900 Campo Grande-MS, Brazil
c Department of Clinical, Toxicological and Bromatological Analysis, School of Phamatological Sciences Ribeirão Preto, USP, 14040-930 Ribeirão Preto, SP, Brazil
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 2 July 2012
Received in revised form
16 November 2012
Accepted 22 November 2012
Available online 1 December 2012
The discovery and development of essential drugs for Chagas disease is a major concern worldwide. New
substituted 1,4-naphthoquinones were synthesized and tested against the infective bloodstream form of
Trypanosoma cruzi, the etiological agent of Chagas disease. These products exhibited substantial activity
against T. cruzi, especially 2-((8E,11Z)-heptadeca-8,11-dienyl)-3-hydroxynaphthalene-1,4-dione (9) with IC50
of 7.8 mM.
Ó 2012 Elsevier Masson SAS. All rights reserved.
Keywords:
Trypanosoma cruzi
Naphthoquinones
Chagas disease
Alkylation reaction
Lapachol
b
-Lapachone
Lawsone
1. Introduction
an intracellular amastigote, which proliferates and then transforms
into a trypomastigote, the T. cruzi form that causes the infection [3].
Chagas disease has two successive phases: acute and chronic.
The acute phase lasts six to eight weeks. Once the acute phase
subsides, most infected patients recover an apparently healthy
state, in which no organ damage can be detected using the current
standard methods of clinical diagnosis [4].
An estimated 10 million people are infected worldwide, mostly
in Latin America [5]. After one hundred years of discovering this
chronic disease, there is still no effective drug treatment. The
therapeutic agents available are benznidazole (RochaganÒ or
RadanilÒ) and Nifurtimox (LampitÒ), which present severe side
effects and they are not effective for chronic phase patients [6,7].
Chagas disease is a long-term debilitating disease caused by the
flagellate protozoan Trypanosoma cruzi, which is mainly trans-
mitted by triatomine insects or by blood transfusion [1]. The usual
mode of transmission of T. cruzi to humans is through the bug bite
on an exposed area of skin. Alternative modes of infection include
blood transfusion, congenital transmission from infected mothers
and the ingestion of contaminated foods [2].
The life cycle of T. cruzi involves a haematophagous triatomine
insect, a vertebrate host, and different parasitic forms. Briefly,
a bloodstream trypomastigote ingested by the insect differentiates
into an epimastigote, which proliferates and, in the posterior
intestine, differentiates into the metacyclic form. This infective
form invades the vertebrate cell and undergoes differentiation into
Naphthoquinones are aromatic cyclic a,b-dienones with a basic
skeleton derived from naphthalene. They are found in various
vegetative parts of higher plants, algae, fungi and, as a product of
the metabolism of some bacteria, possessing broad biological
activities such as antibacterial, anti-inflammatory, antitumor,
anticancer; and trypanocidal [8e10]. Naphthoquinone derivatives
are also widespread in nature and their biological and pharmaco-
logical properties are of great interest such as the alkyl-1,4-
* Corresponding author. Setor de Química (LP4), Centro de Ciências Exatas e
Tecnologia, Universidade Federal de Mato Grosso do Sul, Av. Filinto Müller 1555,
CEP, 79074-460 Campo Grande-MS, Brasil. Tel.: þ55 67 33453676.
E-mail address: denis.lima@ufms.br (D. Pires de Lima).
0223-5234/$ e see front matter Ó 2012 Elsevier Masson SAS. All rights reserved.
http://dx.doi.org/10.1016/j.ejmech.2012.11.034

52
A. Olímpio da Silva et al. / European Journal of Medicinal Chemistry 60 (2013) 51e56
naphthoquinones that comprise a class of compounds that show
important biological activity [11,12].
(Table 1, Entry 14 and 15), probably via a reaction mechanism going
through a secondary radical intermediate.
Lapachol (1) and
b-lapachone (2) [13], (Fig. 1) are very well
known biologically active naphthoquinones. The pharmacological
potential of 1 is explained by its varied biological activity such as
antimicrobial and antifungal [14], cercaricida, molluscicide, anti-
leishmanial [15,16], trypanocidal [17e19], antimalarial [20], anti-
viral [21] and anti-inflammatory [22].
2.2. Biological activity
Compounds 6-15 were tested against bloodstream forms of
T. cruzi and only three of them showed low activity, when
compared with positive control crystal violet (Table 2). Compound
The potential use of
b
-lapachone and semi-synthetic derivatives
9, demonstrated the best trypanocidal activity with IC50 of 7.8 mM.
has already been investigated as a chemotherapeutic agent against
Chagas disease [9]. In the present article, we prepared ten
substituted naphthoquinones from different starting materials
(Table 1) and assayed their activity against T. cruzi.
A comparison of the IC50 values for compounds 9e11 indicates the
importance of substitution the pattern at C-2 of the naphthoquinone.
The insertion of electron-withdrawing groups possibly increases the
redox potential of the naphthoquinoidal structure, leading to an
important biological activity [26]. In most cases, this activity is related
to the ability of quinones to accept one and/or two electrons to form
thecorresponding radical anion ordianion species as well asthe acide
base properties of the compounds [27]. The exchange of hydrogen in
the compound 11 by the methyl (10) or hydroxyl (9) group in the C-2
2. Results and discussion
2.1. Chemistry
position increases the activity from IC50 of 26.4 mM, 16.9 mMe7.8 mM,
respectively. Similarly, the same effect can be observed with
compounds 15 and 14, where trypanocidal activity significantly
increases from IC50 of 48.5 mMe17.4 mM, respectively. Notably, in the
case of compounds 6e8 this effect is reversed, since compound 8,
with no substitution at C-2, was the most active. On the other hand,
compounds 6e8 only differ from compounds 9e11 on the number of
double bonds at the carbon side chain; it is also observed that the
greater unsaturation degree decreases the trypanocidal activity of
compound 11 compared to the compound 8. Oppositely, diunsatu-
rated compounds 9 and 10 have better trypanocidal activity than
monounsaturated 6 and 7.
The synthesis of the substituted 1,4-naphthoquinones was made
by using as starting materials: 1,4-naphthoquinone (3), 2-methyl-
1,4-naphthoquinone (menadione) (4) and, 2-hydroxy-1,4-
naphthoquinone (lawsone) (5) (Table 1). Benli Liu et al. [23] re-
ported the synthesis of vitamin-K derivatives with different side-
chain lengths using radical alkylation reaction. A radical is gener-
ated by decarboxylation of carboxylic acids with silver ions and
ammonium persulfate. However, the insertion of the long chain
alkenyl functionality is a general synthetic problem [24].
The carboxylic functional group allows the introduction of
different chains in order to obtain substituted 1,4-naphthoquinones.
Following the mentioned methodology [23], compounds 3, 4 and 5
were treated with carboxylic acids in the presence of AgNO3 and
(NH4)2S2O8 to give the naphthoquinonesshowninTable 1. Eight new
naphthoquinones were synthesized and assayed against the infec-
tive bloodstream form of T. cruzi. The structures of the synthesized
compounds were unequivocally determined by spectroscopic
techniques, such as 1H and 13C NMR, infrared spectroscopy, MS (EI),
HRMS (ESI), and elemental analysis.
Naphthoquinones 8e11 and 12e15 are described for the first
time and, although the synthesis of 6 and 7 has been reported [24],
we found no results about their biological activity against T. cruzi.
The influence of the large carboxylic acid chains on the yield of
quinones derivatives previously reported [23] is in accordance with
our low yields results for compounds 6e11, resulting from the
reaction with oleic and linoleic acids (Table 1, Entries 1e3 and 4e6).
It is also known that this type of reaction starting with lawsona (5)
usually gives unsatisfactory yields [25] and sometimes, no product
is formed (Table 1, Entries 7, 10 and 13). This was also the result for
alkylation of menadione (4) with octanoic acid (Table 1, Entry 8).
Treatment of 1,4-naphthoquinone (3) with octanoic acid and 5-
phenylpentanoic, under the same conditions, led to the formation
of the dialkylated products 12 and 13 (Table 1, Entry 9 and 12). As
for the reaction of 3-(4-methoxyphenyl) propanoic acid with 3e4,
compounds 14 and 15 were obtained as a racemic mixture
Considering compounds with attached hydroxyl group, we
observed that the prepared compounds 6 (IC50 10.6
7.8 M), are remarkably more active (Table 2) than known
compounds such as lawsone (5) with IC50 > 2500 M and lapachol
mM) and 9 (IC50
m
m
(1) with IC50 of 410.8 (Table 3), suggesting that the presence and the
size of alkyl chain, increases the activity against T. cruzi.
Recently, it was reported that the attachment of a 1,2,3-triazole
group in the 1,4-naphthoquinoidal structure (compound 16, Table 3)
led to an enhancement of its pharmacological activity showing an IC50
of 10.9 while benznidazole presents IC50 of 103.6 [26]. If compared to
the synthesized compounds 8, 11 and 15, that are substituted in only
one position, the triazole 16 is two and four times more active than 11
and 15 respectively, however, it is less active than 8.
Another interesting result was related to the activity of
compounds 12 and 13, derived from dialkylation of 1,4-
naphthoquinone, that showed IC50 of 123.7
mM and 25.1 mM,
respectively. Compound 12 is the least active of the entire series but
13 is more active than 12 because it bears aromatic rings in its
structure which could be related with hydrophobic properties.
The obtained results can be considered very significant and can
lead to develop potential Chagas disease drug candidates.
Compound 9 could be considered a good prototype after investi-
gation of its cytotoxicity in mammalian cells.
3. Conclusions
O
O
We prepared substituted 1,4-naphtoquinones and their trypa-
nocidal activity was evaluated. Data of all activities revealed that
compound 9 displayed the highest activity. Within the limits of the
compounds synthesized and examined, the structure-activity
might be related to the position of substitution, the functional
groups and the degree of unsaturation of carbon side chain
attached to 1,4-naphthoquinoidal structure. Therefore, the
prepared compounds merit further research as potential drugs
against Chagas disease.
H
O
O
O
O
( )
(2)
b-lapachone (2).
1
Fig. 1. Chemical structure of lapachol (1) e

A. Olímpio da Silva et al. / European Journal of Medicinal Chemistry 60 (2013) 51e56
53
Table 1
Synthesis of naphthoquinones.
Entry
Naphthoquinone
Carboxylic acid
Producta
6
Yield. [%]
1
5 (R1 ¼ OH)
8
2
3
4 (R1 ¼ CH3)
3 (R1 ¼ H)
7
8
67
40
4
5 (R1 ¼ OH)
9
39
5
6
4 (R1 ¼ CH3)
3 (R1 ¼ H)
10
11
13
20
7
5 (R1 ¼ OH)
n. r.
e
8
9
4 (R1 ¼ CH3)
3 (R1 ¼ H)
n. r.
12
e
40
10
5 (R1 ¼ OH)
n. r.
e
11
12
4 (R1 ¼ CH3)
3 (R1 ¼ H)
n. r.
13
e
41
13
5 (R1 ¼ OH)
n. r.
e
14
15
4 (R1 ¼ CH3)
3 (R1 ¼ H)
14
15
52
30
a
n. r. ¼ no reaction.
4. Experimental
spectrometer. The main fragments were described as a relation
between atomic mass units and the charge (m/z) and the relative
abundance inpercentage of the base-peak intensity. Infrared spectra
were recorded on a Bomen FT-IR-MB100 Spectrometer. HRMS and
Elemental analysis results were obtained in the services of Central
Analytical e Institute of Chemistry e USP.
4.1. General
All the laboratory grade reagents were commercial. Purifications
of compounds were made by column chromatography (CC) using
Merck silica gel 60 (230e400 mesh) and a mixture of hexane and
ethyl acetate was used for elution. All the reactions were monitored
by TLC using Merck silica gel 60. 1H (300 MHz) and 13C NMR
(75 MHz) spectra were recorded with a Bruker DPX-300 spectrom-
eter and, calibrated with residual non-deuterated solvent as an
internal reference. Chemical shifts are reported in ppm and tetra-
4.2. General preparation of 6e15
General procedure for the synthesis of substituted 1,4-
naphthoquinones 6e15 1,4-naphthoquinone (3), 2-hydroxy-1,4-
naphthoquinone (4) and 2-methyl-1,4-naphthoquinone (5) was as
described in literature [1e3]. A solution of (NH4)2S2O8 (1,0 g) in H2O
(10 mL) was added dropwise over 90e120 min to a stirred suspen-
sion of H2O (10 mL), CH3CN (20 mL), AgNO3 (0.25 g), 2, 4 and 5 (0.2 g)
methylsilane was used as the internal standard (
coupling constants (J) in Hertz. Mass spectra (EI, 70 eV) were run on
Shimadzu CGMS QP2010 Plus gas chromatography mass
d
¼ 0 ppm) and
a

54
A. Olímpio da Silva et al. / European Journal of Medicinal Chemistry 60 (2013) 51e56
Table 2
Activity of the compounds 6e15 against bloodstream trypomastigote forms of T. cruzi.
Compound
Concentration (
m
M) ꢂ% lysis
IC50 (mM)
0.5
2.0
8.0
32.0
6
7
13.1 ꢃ 5.5
27.2 ꢃ 4.3
22.5 ꢃ 7.6
51.3 ꢃ 6.3
57.6 ꢃ 3.9
10.6
32.6
25.1 ꢃ 1.9
35.1 ꢃ 3.4
34.0 ꢃ 4.2
8
37.2 ꢃ 1.8
44.5 ꢃ 1.9
15.2 ꢃ 3.1
0.0
45.5 ꢃ 4.6
47.6 ꢃ 2.3
25.6 ꢃ 1.0
7.8 ꢃ 3.5
8.9 ꢃ 4.7
46.1 ꢃ 2.3
42.9 ꢃ 3.7
47.1 ꢃ 7.0
30.9 ꢃ 5.4
10.6 ꢃ 3.5
49.2 ꢃ 4.1
50.8 ꢃ 1.0
44.5 ꢃ 1.9
49.2 ꢃ 3.0
18.3 ꢃ 6.3
8.1
9
7.8
10
11
12
16.9
26.4
8.1 ꢃ 0.8
123.7
25.1
13
14
3.0 ꢃ 1.6
21.5 ꢃ 2.7
24.6 ꢃ 5.9
35.1 ꢃ 2.3
34.0 ꢃ 6.3
44.0 ꢃ 8.7
55.0 ꢃ 3.8
12.0 ꢃ 3.3
17.4
48.5
15
0.0
10.5 ꢃ 4.1
14.1 ꢃ 4.6
38.7 ꢃ 5.7
Positive control: crystal violet (IC50 ¼ 31
mM); negative control: DMSO.
and carboxylic acid (1.5 mmol) at 70e80 ꢀC. After stirring for more
than 20 min, the resulting mixture was cooled, extracted with ethyl
acetate, the organic phase was washed with NaHCO3, dried over
MgSO4, filtered, and the solvent was evaporated under reduced
pressure. The product was purified by flash chromatography.
4.2.1. (E)-2-(Heptadec-8-enyl)-3-hydroxynaphthalene-1,4-dione (6)
Compound 6 was obtained as yellow oil, 8% yield. IR (KBr, cmꢁ1):
n
3382, 2923, 2854, 1650, 725. 1H NMR (300 MHz, CDCl3)
d: 0.84
(3H, t, J ¼ 6.0 Hz), 1.00e1.40 (22H, m), 1.98 (4H, m), 2.57 (2H, t,
J ¼ 9.0 Hz), 5.31 (2H, t, J ¼ 6.0 Hz), 7.68 (2H, td, J ¼ 6.0 Hz e 3.0 Hz),

A. Olímpio da Silva et al. / European Journal of Medicinal Chemistry 60 (2013) 51e56
55
Table 3
(CH), 153.01 (C), 181.45 (C]O), 184.70 (C]O). MS (EI) m/z (rel.
int.,%): 55 (100), 69 (60), 187 (60), 408 (15) [M]þꢄ. Anal. Calcd for
Biological activity of lapachol (1), lawsone (5) and triazole (16) against bloodstream
trypomastigote form of T. cruzi.
C27H36O3: C, 79.37; H, 8.88; O, 11.75. Found: C, 79.56; H, 8.86.
Structures
IC50
(
m
M)
Ref.
4.2.5. 2-((8E,11E)-Heptadeca-8,11-dienyl)-3-methylnaphthalene-
1,4-dione (10)
(1)
410.8 ꢃ 53.5
[28]
Compound 10 was obtained as yellow oil,13% yield. IR (KBr, cmꢁ1):
n
2923, 2854, 1658, 717. 1H NMR(300 MHz, CDCl3)
d: 0.83 (3H, t,
J ¼ 6.0 Hz), 1.00e1.50 (16H, m), 1.99 (4H, m), 2.14 (3H, s), 2.58 (2H, t,
J ¼ 6.0 Hz), 2.73 (2H, m), 5.32 (4H, m), 7.63 (2H, td, J ¼ 6.0 Hz e 3.0 Hz),
8.00 (2H, dd, J ¼ 6.0 Hz e 3.0 Hz). 13C NMR (75 MHz, CDCl3)
d: 12.50
(5)
>2500
[29]
[26]
(CH3), 14.02 (CH3), 22.48 (CH2), 22.59 (CH2), 25.53 (CH2), 26.99 (CH2),
27.10 (2CH2), 28.00e30.00 (5 CH2), 31.82 (CH2), 126.04 (CH), 126.14
(CH), 127.81 (CH), 127.94 (CH), 129.92 (CH), 130.06 (CH), 132.05 (C),
132.09 (C), 133.14 (CH), 133.17 (CH), 142.94 (C), 147.40 (C), 184.51 (C]
O), 185.17 (C]O). MS (EI) m/z (rel. int.,%): 55 (35), 81 (19), 187 (100),
406 (15) [M]þꢄ. Anal. Calcd for C28H38O2: C, 82.71; H, 9.42; O, 7.87.
Found: C, 82.79; H, 9.49.
(16)
10.9 ꢃ 1.8
4.2.6. 2-((8E,11E)-Heptadeca-8,11-dienyl)naphthalene-1,4-dione (11)
Compound 11 was obtained as yellow oil, 20% yield. 1H NMR
(300 MHz, CDCl3)
d
: 0.85 (3H, t, J ¼ 6.0 Hz),1.00e1.50 (16H, m), 2.00
8.06 (2H, dd, J ¼ 6.0 Hz e 3.0 Hz). 13C NMR(75 MHz, CDCl3)
d
: 14.08
(2H, m), 2.54 (2H, m), 2.74 (2H, m), 5.33 (4H, m), 6.75 (1H, s), 7.65
(CH3), 22.65 (CH2), 27.17 (2 CH2), 28.28 (CH2), 29.00e30.00 (9 CH2),
31.88 (CH2), 124.81 (C), 126.01 (CH), 126.74 (CH), 129.44 (C), 129.81
(CH), 129.89 (CH), 132.79 (CH), 132.94 (C), 134.77 (CH), 153.00 (C),
(2H, td, J ¼ 6.0 Hz e 3.0 Hz), 8.00 (2H, dd, J ¼ 6.0 Hz e 3.0 Hz). 13
C
NMR (75 MHz, CDCl3) d: 14.03 (CH3), 22.53 (CH2), 25.57 (CH2), 27.00
(CH2), 27.14 (2CH2), 27.95 (CH2), 29.00e30.00 (5 CH2), 31.85 (CH2),
126.09 (CH), 126.51 (CH), 127.84 (CH), 127.97 (CH), 129.81 (C),
129.97 (CH), 130.12 (CH), 132.17 (C), 133.17 (CH), 133.50 (CH), 134.62
(CH), 147.10 (C), 185.06 (C]O), 185.14 (C]O). MS (EI) m/z (rel.
int.,%): 55 (84), 81 (49), 95 (35), 160 (26), 173 (100), 197 (30), 392
(10) [M]þꢄ. Anal. Calcd for C27H36O2: C, 82.61; H, 9.24; O, 8.15.
Found: C, 82.89; H, 9.41.
181.45 (C]O), 184.67 (C]O). MS (EI) m/z (rel. int.,%): 188.0 (100)
384 (10); 410 (76) [M]þ
.
ꢄ
4.2.2. (E)-2-(Heptadec-8-enyl)-3-methylnaphthalene-1,4-dione (7)
Compound 7 was obtained as yellow oil, 67% yield. IR (KBr,
cmꢁ1):
n d: 0.83
2923, 2854, 1658, 717. 1H NMR (300 MHz, CDCl3)
(3H, t, J ¼ 6.0 Hz), 1.0e1.5 (22H, m), 1.97 (4H, m), 2.14 (3H, s), 2.58
(2H, t, J ¼ 9.0 Hz), 5.29 (4H, tl, J ¼ 6.0 Hz), 7.62 (2H, td, J ¼ 6.0 Hz e
3.0 Hz), 8.00 (2H, dd, J ¼ 6.0 Hz e 3.0 Hz). 13C NMR (75 MHz, CDCl3)
4.2.7. 2,3-Diheptylnaphthalene-1,4-dione (12)
Compound 12 was obtained as yellow oil, 40% yield. IR (KBr, cmꢁ1):
d
: 12.52 (CH3), 14.03 (CH3), 27.02 (CH2), 27.09 (CH2), 27.14 (CH2),
n d: 0.84 (6H, t,
2954, 2854, 1658, 721. 1H NMR (300 MHz, CDCl3)
28.68 (CH2), 29.0e30.0 (9 CH2), 31.84 (CH2), 126.06 (CH), 126.16
(CH), 129.65 (CH), 129.89 (CH), 132.07 (C), 132.11 (C), 133.14 (CH),
J ¼ 6.0 Hz), 1.17e1.47 (20H, m), 2.55 (4H, t, J ¼ 6.0 Hz), 7.61 (2H, dd,
J ¼ 6.0 Hz e 3.0 Hz), 8.00 (2H, dd, J ¼ 6.0 Hz e 3.0 Hz).13C NMR (75 MHz,
133.17 (CH), 142.95 (C), 147.43 (C), 185.19 (C]O), 184.53 (C]O). MS
CDCl3) d: 14.01 (2CH3), 22.58 (2CH2), 26.98(2CH2), 28.99 (2CH2), 29.58
(EI) m/z (rel. int.,%): 187 (100), 408 (70) [M]þ
.
(2CH2), 30.03 (2CH2), 31.68 (2CH2), 126.05 (2CH), 132.16 (2C), 133.12
(2CH),147.11 (2C),185.02(2C]O). MS (EI) m/z (rel.int.,%):186(39),187
(78),199 (33), 213 (13), 255 (47), 270 (16), 354 (100) [M]þꢄ. Anal. Calcd
for C24H34O2: C, 81.31; H, 9.67; O, 9.03. Found: C, 81.44; H, 9.71.
ꢄ
4.2.3. (E)-2-(Heptadec-8-enyl)naphthalene-1,4-dione (8)
Compound 8 was obtained as yellow oil, 40% yield. IR (KBr,
cmꢁ1):
n d: 0.84
2923, 2850, 1666, 721. 1H NMR (300 MHz, CDCl3)
(3H, t, J ¼ 6.0 Hz), 1.0e1.5 (24H, m), 1.55 (2H, m), 1.99 (4H, sl), 2.53
(2H, t, J ¼ 9.0 Hz), 5.31 (2H, tl, J ¼ 6.0 Hz), 6.76 (1H, s), 7.69 (2H, td,
J ¼ 6.0 Hz e 3.0 Hz), 8.00 (2H, dd, J ¼ 6.0 Hz e 3.0 Hz). 13C NMR
4.2.8. 2,3-Bis(4-phenylbutyl)naphthalene-1,4-dione (13)
Compound 14 was obtained as yellow oil, 41% yield. IR (KBr,
cmꢁ1):
n d: 1.53 (4H, q,
2931, 1658, 721. 1H NMR (300 MHz, CDCl3)
(75 MHz, CDCl3)
d
: 14.09 (CH3), 22.65 (CH2), 27.13 (CH2), 27.18 (CH2),
J ¼ 9.0 Hz e 6.0 Hz), 1.77 (4H, q, J ¼ 9.0 Hz e 6.0 Hz), 2.61e2.69 (8H,
27.97 (CH2), 29.11 (CH2), 29.0e30.0 (8 CH2), 31.87 (CH2), 125.97
(CH), 126.55 (CH), 129.69 (CH), 129.98 (CH), 132.06 (C), 132.28 (C),
m), 7.17e7.32 (12H, m), 7.67 (2H, dd, J ¼ 6.0 Hz e 3.0 Hz), 8.10 (2H,
dd, J ¼ 6.0 Hz e 3.0 Hz). 13C NMR (75 MHz, CDCl3)
d: 26,81 (2CH2),
133.55 (CH), 133.57 (CH), 134.67 (CH),
d
151.94 (C),
d
185.22 (2C]O).
29,12 (2CH2), 31,70 (2CH2), 35,56 (2CH2), 125,67 (2CH), 126,08
(2CH), 128,22 (4CH), 128,29 (4CH), 132,07 (2C), 133,20 (2CH), 142,09
(2C), 146,89 (2C), 184,93 (2C]O). MS (EI) m/z (rel. int.,%): 91 (100),
131 (48), 173 (10) 187 (50), 289 (30), 422 (50) [M]þꢄ. HRMS (ESI)
Calcd for [C30H30O2 þ Na]þ: 445.2145, Found: 445.2142.
MS (EI) m/z (rel. int.,%): 173 (100), 368 (10), 394 (40) [M]þꢄ. HRMS
(ESI) Calcd for [C27H38O2 þ Na]þ: 417.2771, Found: 417.2770.
4.2.4. 2-((8E,11Z)-Heptadeca-8,11-dienyl)-3-hydroxynaphthalene-
1,4-dione (9)
Compound 9 was obtained as yellow oil, 39% yield. IR (KBr,
4.2.9. 3-(4-Methoxyphenyl)-3-(3-methyl-1,4-dioxo-1,4-
dihydronaphthalen-2-yl) propanoic acid (14)
cmꢁ1):
CDCl3)
n
3382, 2923, 2854, 1662, 1650, 725. 1H NMR (300 MHz,
d
: 0.85 (3H, t, J ¼ 6.0 Hz), 1.00e1.50 (16H, m), 1.98 (4H, m),
Compound 14 was obtained as yellow oil, 52% yield. IR (KBr,
2.57 (2H, t, J ¼ 9.0 Hz), 2.74 (2H, m), 5.31 (4H, m), 7.68 (2H, td,
cmꢁ1): 2958, 2835, 1658, 1704. 1H NMR (300 MHz, CDCl3)
n d: 2.31
J ¼ 6.0 Hz e 3.0 Hz), 8.10 (2H, dd, J ¼ 6.0 Hz e 3.0 Hz). 13C NMR
(3H, s), 3.24e3.46 (2H, dd, J ¼ 15.0 Hz e 6.0 Hz), 3.73 (3H, s), 4.72
(1H, tl, J ¼ 9.0 Hz), 6.80 (2H, d, J ¼ 9.0 Hz), 7.23 (2H, d, J ¼ 9.0 Hz),
7.61e7.64 (2H, m), 7.93e8.02 (2H, m). 13C NMR (75 MHz, CDCl3):
(75 MHz, CDCl3) d: 14.08 (CH3), 22.65 (CH2), 23.33 (CH2), 25.59
(CH2), 27.17 (2CH2), 28.26 (CH2), 29.00e30.00 (5CH2), 31.86 (CH2),
124.81 (C), 126.01 (CH), 126.73 (CH), 127.90 (CH), 127.92 (CH),
129.81 (CH), 129.88 (CH), 130.10 (C), 132.81 (CH), 132.90 (C), 134.78
d
12.92 (CH3), 37.15 (CH2), 39.93 (CH), 55.16 (CH3), 113.96 (2CH),
126.11 (CH), 126.35 (CH), 128.71 (2CH), 131.70 (C), 132.24 (2C),

56
A. Olímpio da Silva et al. / European Journal of Medicinal Chemistry 60 (2013) 51e56
133.32 (CH), 133.47 (CH), 144.79 (C), 146.67 (C), 158.30 (C), 177.82
(C]O), 184.69 (C]O), 185.33 (C]O). MS (EI) m/z (rel. int.,%): 135
(100), 304 (75), 320 (37), 335 (3), 350 (3) [M]þꢄ. Anal. Calcd for
References
[1] E.N. Da Silva Júnior, M.A.B.F. de Moura, A.V. Pinto, M.C.F.R. Pinto, M.C.B.V. de
Souza, A.J. Araújo, C. Pessoa, L.V. Costa-Lotufo, R.C. Montenegro, M.O. de
Moraes, V.F. Ferreira, M.O.F. Goulart, J. Braz. Chem. Soc. 20 (2009) 635e643.
[2] S.D. Pena, C.R. Machado, A.M. Macedo, Mem. Inst. Oswaldo Cruz 104 (2009)
108e114.
C
21H18O5: C, 71.99; H, 5.18; O, 22.83. Found: C, 72.08; H, 5.09.
4.2.10. 3-(1,4-Dioxo-1,4-dihydronaphthalen-2-yl)-3-(4-
methoxyphenyl) propanoic acid (15)
[3] M.C. Fernandes, E.N. da Silva Junior, A.V. Pinto, S.L. de Castro, R.F.S. Menna-
Barreto, Parasitology 139 (2012) 26e36.
Compound 15 was obtained as red oil, 30% yield. IR (KBr, cmꢁ1):
n
[4] A. Moncayo, A.C. Silveira, Mem. Inst. Oswaldo Cruz 104 (2009) 17e30.
[5] Chagas Disease (American Trypanosomiasis) Fact Sheet 340 (June
2010).http://www.who.int/mediacentre/factsheets/fs340/en/index.html.
[6] R.S.F. Silva, E.M. Costa, U.L.T. Trindade, D.V. Teixeira, M.C.F.R. Pinto, G.L. Santos,
V.R.S. Malta, C.A. de Simone, A.V. Pinto, S.L. de Castro, Eur. J. Med. Chem. 41
(2006) 526e530.
[7] S.B. Ferreira, K. Salomão, F.C. Silva, A.V. Pinto, C.R. Kaiser, A.C. Pinto,
V.F. Ferreira, S.L. de Castro, Eur. J. Med. Chem. 46 (2011) 3071e3077.
[8] K.C.G. De Moura, K. Salomão, R.F.S. Menna-Barreto, F.S. Emery, M.C.F.R. Pinto,
A.V. Pinto, S.L. de Castro, Eur. J. Med. Chem. 39 (2004) 639e645.
[9] A. Riffel, L.F. Medina, V. Stefani, R.C. Santos, D. Bizani, A. Brandelli, Braz. J. Med.
Biol. Res. 35 (2002) 811e818.
[10] X.R. Cui, M. Tsukada, N. Suzuki, T. Shimamura, L. Gao, J. Koyanagi, F. Komada,
S. Saito, Eur. J. Med. Chem. 43 (2008) 1206e1215.
[11] I. Menegazzo, G. Sandonà, S. Moro, V. Sheeba, G. Zagotto, Tetrahedron Lett. 41
(2000) 6631e6634.
[12] S.B. Ferreira, D.R. Rocha, J.W.M. Carneiro, W.C. Santos, V.F. Ferreira, Synlett 11
(2011) 1551e1554.
3421, 2927, 2838, 1662. 1H NMR (300 MHz, CDCl3)
d: 2.88e3.08 (2H,
dd, J ¼ 15.0 Hz e 6.0 Hz), 3.72 (3H, s), 4.76 (1H, tl, J ¼ 6.0 Hz), 6.77 (1H,
sl), 6.81 (2H, d, J ¼ 9.0 Hz), 7.20 (2H, d, J ¼ 9.0 Hz), 7.64e7.68 (2H, m),
7.97e8.01 (2H, m). 13C NMR (75 MHz, CDCl3)
d: 39.21 (CH), 38.30
(CH2), 55.16 (CH3), 114.27 (2CH), 125.96 (CH), 126.80 (CH), 128.98
(2CH), 130.07 (CH), 131.37 (C), 131.72 (C), 132.12 (C), 133.71 (CH),
133.76 (CH), 152.03 (C), 158.76 (C), 176.45 (C]O), 184.04 (C]O),
185.12 (C]O). MS (EI) m/z (rel. int.,%): 247 (26), 261 (18), 277 (100),
290 (43), 318 (30), 336 (8) [M]þꢄ. Anal. Calcd for C20H16O5: C, 71.42; H,
4.79; O, 23.78. Found: C, 71.66; H, 4.86.
5. Trypanocidal assay
[13] S. Claessens, B. Kesteleyn, T.N. Van, N. De Kimpe, Tetrahedron 62 (2006)
8419e8424.
[14] P. Guiraud, R. Steiman, G.M. Campos-Takaki, F. Seigle-Murandi, B.M. Simeon,
Planta Med. 60 (1994) 373e374.
[15] M.A. Lima, J.M. Barbosa Filho, C.A. Merlic, B.C. Doroh, J.G.S. Maia, M.S. Silva,
E.V.L. Cunha, Biochem. Syst. Ecol. 32 (2004) 347e349.
[16] N.M.F. Lima, C.S. Correia, P.A.L. Ferraz, A.V. Pinto, M.C.R.F. Pinto, A.E.G. Santana,
M.O.F. goulart, J. Braz. Chem. Soc. 13 (2002) 822e829.
The bioassays were made using the blood of infected Swiss
albino mice, which was collected by cardiac puncture at the peak of
parasitemic infection (7th day of infection for Y strain). The infected
blood was diluted with the blood of healthy mice to achieve
a concentration of 106 trypomastigote forms mlꢁ1. The compounds
(6e15) solutions were prepared in dimethyl sulfoxide (DMSO) and
were added into the infected mouse blood to provide concentra-
[17] A. Boveris, R. Docampo, J.F. Turrens, A.O. Stoppani, Biochem. J. 175 (1978)
431e439.
tions of (0.5), (2.0), (8.0) and (32.0) mM, respectively. The plates
[18] A. Boveris, A.O. Stoppani, Medicina Buenos Aires 38 (1978) 259e265.
[19] F.S. Cruz, R. Docampo, A. Boveris, An. Acad. Bras. Cienc. 50 (1978) 598.
[20] V.F. Andrade-Neto, M.G. Brandão, F.Q. Oliveira, V.W. Casali, B. Njaine,
M.G. Zalis, L.A. Oliveira, A.U. Krettli, Phytother. Res. 18 (2004) 634e639.
[21] E.P. Sacau, A. Estevez-Braun, A.G. Ravelo, E.A. Ferro, H. Tokuda, T. Mukainakac,
H. Nishinoc, Bioorgan. Med. Chem. 11 (2003) 483e488.
were incubated at 4 ꢀC for 24 h. Afterwards, the trypanocidal
activity was evaluated by counting the trypomastigote forms of the
remaining parasites, following the method described [30e32]. The
bioassays were made in triplicate on microtiter plates (96 wells),
[22] E.R. de Almeida, A.A. Silva Filho, E.R. Santos, C.A. Lopes, J. Ethnopharmacol. 29
(1990) 239e241.
which contained 200
controls containing either DMSO or crystal violet at IC50 31
were run in parallel. The activities of the compounds were
expressed as IC50 values, corresponding to the concentration that
causes lysis on 50% of the parasites.
ml of mixture per well. Negative and positive
mM
[23] B. Liu, L. Gu, J. Zhang, Recl. Trav. Chim. Pays Bas. 110 (1991) 99e103.
_
[24] D. Tauraite, V. Razumas, E. Butkus, Chem. Phys. Lipids 159 (2009) 45e50.
[25] S. Spyroudius, Molecules 5 (2000) 1291e1330.
[26] E.N. da Silva Júnior, I.M.M. de Melo, E.B.T. Diogo, V.A. Costa, J.D. de Souza Filho,
W.O. Valença, C.A. Camara, R.N. de Oliveira, A.S. de Araújo, F.S. Emery, M.R. dos
Santos, C.A. de Simone, R.F.S. Menna-Barreto, S.L. de Castro, Eur. J. Med. Chem.
52 (2012) 304e312.
[27] F.A. Molfeta, A.T. Bruni, K.M. Honório, A.B.F. da Silva, Eur. J. Med. Chem. 40
(2005) 329e338.
Acknowledgments
The authors would like to thank FUNDECT/MS, PROPP-UFMS
and CNPq-Brasil, for providing financial support and infrastructure.
We also owe a debt of gratitude to Dr. Roberto da Silva Gomes
(UFMS) and Professor Paulo Olivato (USP) for the Elemental Anal-
ysis and Mass Spectroscopy experiments.
[28] A.V. Pinto, C. Neves-Pinto, M.C.F.R. Pinto, R.M. Santa-Rita, C. Pezzella, S.L. de
Castro, Arzneim-Forsch 47 (1997) 74.
[29] K.C. Moura, F.S. Emery, C. Neves-Pinto, M.C.F.R. Pinto, A.P. Dantas, K. Salomão,
S.L. de Castro, A.V. Pinto, J. Braz. Chem. Soc. 12 (2001) 325.
[30] A.G. Neto, A.A. da Silva Filho, J.M.L.C. Costa, A.H.C. Vinholis, G.H.B. Souza,
W.R. Cunha, M.L.A.E. Silva, S. Albuquerque, J.K. Bastos, Phytomed 11 (2004)
622e665.
[31] A.R.P. Ambrozin, J. Mafezoli, P.C. Vieira, J.B. Fernandes, M.F.G.F. da Silva,
J.A. Ellena, S. Albuquerque, J. Braz. Chem. Soc. 16 (2005) 34e439.
[32] V.A. de Souza, R. da Silva, A.C. Pereira, V.A. Royo, J. Saraiva, M. Montanheiro,
G.H.B. de Souza, A.A. da Silva Filho, M.D. Grando, P.M. Donate, J.K. Bastos,
S. Albuquerque, M.L.A. Silva, Bioorg. Med. Chem. Lett. 15 (2005) 303e307.
Appendix A. Supplementary data
Supplementary data associated with this article can be found in
the online version, at http://dx.doi.org/10.1016/j.ejmech.2012.11.034.