Synthesis and evaluation of (-)-Massoialactone and analogues as potential anticancer and anti-inflammatory agents

Article abstract of DOI:10.1016/j.ejmech.2014.02.013

(-)-Massoialactone, an α,β-unsaturated δ-lactone isolated from Cryptocarya massoia, and five analogues were synthesized and their antiproliferative and anti-inflammatory activities were evaluated. The lactones were able to mimic the "core" functional grou

Full text of DOI:10.1016/j.ejmech.2014.02.013

European Journal of Medicinal Chemistry 76 (2014) 291e300
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis and evaluation of (ꢀ)-Massoialactone and analogues as
potential anticancer and anti-inflammatory agents
Maria E.S.B. Barros a, Juliano C.R. Freitas a, Juliana M. Oliveira a, Carlos H.B. da Cruz a,
Paulo B.N. da Silva b, Larissa C.C. de Araújo b, Gardenia C.G. Militão b, Teresinha G. da Silva c,
,
Roberta A. Oliveira a, Paulo H. Menezes a
*
a Universidade Federal de Pernambuco, Departamento de Química Fundamental, Cidade Universitária, Av. Jornalista Aníbal Fernandes, s/n, Recife, PE 50740-
560, Brazil
b Universidade Federal de Pernambuco, Departamento de Fisiologia e Farmacologia, CCB, Cidade Universitária, Recife, PE, Brazil
c Universidade Federal de Pernambuco, Departamento de Antibióticos, Cidade Universitária, Recife, PE, Brazil
a r t i c l e i n f o
a b s t r a c t
Article history:
(ꢀ)-Massoialactone, an
a,b-unsaturated d-lactone isolated from Cryptocarya massoia, and five analogues
Received 22 July 2013
Received in revised form
6 January 2014
Accepted 8 February 2014
Available online 11 February 2014
were synthesized and their antiproliferative and anti-inflammatory activities were evaluated. The lac-
tones were able to mimic the “core” functional group required for the biological activity of their parent
natural compounds suggesting that substantially altered analogues may retain their properties.
Ó 2014 Elsevier Masson SAS. All rights reserved.
Keywords:
Massoialactone
Antitumoral activity
Anti-inflammatory activity
Lactones
Tellurides
1. Introduction
a,b-unsaturated d-lactone moiety [8] which leads to selective in-
hibition of the proteineprotein interaction in the ternary CRM1-
RAN-cargo protein complex.
The a,b-unsaturated d-lactone unit is present in several com-
pounds isolated from plants and marine organisms. These com-
pounds exhibit different structural complexities and a broad range
of biological activities. Examples are fostriecin, cytostatin, lep-
tomicin B, goniothalamin, and massoialactone (Fig. 1).
Fostriecin and cytostatin are structurally related compounds
produced by Streptomyces pulveraceus [1] and Streptomyces sp.
MJ654-Nf4 [2], respectively. These compounds are described as
potent inhibitors of a subset of PPP-family serine/threonine protein
phosphatases, being fostriecin a potent inhibitor of PP2/PP4, and
cytostatin a potent and selective inhibitor of PP2A [3].
Goniothalamin is a styryl lactone isolated from various species
of the genus Goniothalamus [9], and displays significant cytotoxic
and anti-proliferative activities against a variety of cancer cell lines
[10]. This lactone also displays other biological activities such as
insecticidal [11], larvicidal [12], antifungal [13], antimicrobial [14],
and trypanocidal [15].
(ꢀ)-Massoailactone, 1 was first isolated from the bark of Cryp-
tocarya massoia, and later from other sources [16]. The structural
simplicity of (ꢀ)-Massoialactone,1 compared to its
a,b-unsaturated
d
-lactone analogues shown of Fig. 1 makes this compound a
Leptomycin B (LMB) is produced by Streptomyces sp. strain ATS
1287 [4], and attracted attention due to its antitumor [5] and
antifungal [6] activities. It is a potent inhibitor of the nuclear export
of proteins [7] and its mode of action involves the binding to the
chromosome maintenance region I (CRM1) exporting through its
particularly attractive target and many approaches to 1 have been
reported [17]. In addition, (ꢀ)-Massoialactone is a powerful skin
irritant and produces systolic standstill in frog heart muscles [18].
Moreover, it showed good antimicrobial activity against Staphylo-
coccus aureus, B. subtilis and E. coli [19].
The synthesis of relatively simple molecules which could be able
to effectively mimic the key elements for the biological activity of a
complex natural product such as those depicted in Fig. 1 is a subject
of the great interest. As the “core” functional group required for the
* Corresponding author.
E-mail
addresses:
paulo.menezes@pq.cnpq.br,
pmenezes@ufpe.br
(P.H. Menezes).
http://dx.doi.org/10.1016/j.ejmech.2014.02.013
0223-5234/Ó 2014 Elsevier Masson SAS. All rights reserved.

292
M.E.S.B. Barros et al. / European Journal of Medicinal Chemistry 76 (2014) 291e300
Fig. 1. Examples of natural products containing a
a
,
b-unsaturated
d-lactone unit.
in vitro antiproliferative activity of cytostatin, fostriecin, leptomycin
and goniothalamin is the -unsaturated -lactone, substantially
a,
b
d
altered analogues of these natural products may retain their
properties.
In this work, we performed molecular docking simulations on
(ꢀ)-Massoialactone and some analogues in order to gain a better
understanding of how these compounds would interact with CRM1,
one of the most important molecular targets for the design of new
inhibitors that could mimic natural toxins such as LMB. The results
of this study provided a new insight for the synthesis of these
compounds and the in vitro evaluation of their antiproliferative and
anti-inflammatory properties.
Table 1
Docking interaction energy of
CRM1.
a
,
b
-unsaturated
d
-lactones, 1 and 10aee against
G (Kcal molꢀ1
Compound
D
)
1
2
3
4
ꢀ6.42
ꢀ5.61
ꢀ5.61
ꢀ7.25
1
2. Results and discussion
2.1. Docking analysis
10a
10b
10c
Leptomycin B (LMB) efficiently suppresses the nuclear export by
inhibiting CRM1, a nuclear export receptor responsible for shuttling
a large number of proteins and chemotherapeutic targets [19],
playing an essential role in canonical nuclear export signal (NES)-
dependent nuclear export, including major tumor suppressor
proteins (TSPs).
The crystallographic structure of CRM1-RAN in complex with
inhibitors were taken from the Research Collaboratory of Structural
Bioinformatics Protein Data Bank (PDB 4HAT) [20]. The ligands and
water molecules were extracted from the PDB file. All of the cal-
culations were performed with the package docking program
Autodock Tools 4.2 [21]. Initially, the structure was built using the
Gauss View 4.1 [22] and optimized using the semi-empiric model
AM1 [23] using the atomic charge units (Gasteiger model) [24] were
marked and the flexibility of both receptor and ligand were deter-
mined using the standard program parameters, in which it was
permitted to twist the lactone side chain. The electrostatic energy
maps, atom-specific affinity and desolvation were calculated using
Autogrid 4.2 with the centre grid at ꢀ39.174, 72.955, 29.907; with
5
6
ꢀ7.72
ꢀ7.21
10d
ꢀ
ꢀ
19.5 ꢁ 15.75 ꢁ 15.75 A dimensions, and 0.375 A spacing. Fifty
populations each with 2.500.000 fits were evaluated using the
Generic Algorithm of energy minimization with the Autodock 4.2
program. The predicted binding energies of the envisioned com-
pounds into the CRM1 active site are listed in Table 1.
10e

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293
From Table 1 it can be seen that the shortening of the alkyl side
chain of the lactone resulted in a large difference in the binding
energy to CRM1 for (ꢀ)-Massoilactone, 1 and 10a (Table 1, entries 1
and 2), supporting the hypothesis that the side chain plays an
important role in the molecular recognition.
The addition of an unsaturated side chain to the lactone proved
to have no effect in the binding energy (Table 1, entry 3), however,
the presence of an heteroatom in the side chain, greatly enhanced
the interaction with the CRM1 active site and the observed binding
energy was ꢀ7.25 kcal/mol (Table 1, entry 4).
The replacement of an alkyl side chain by an aromatic side chain,
also enhanced the interaction with the CRM1 active site, with the
calculated binding energy for compound 10e of ꢀ7.21 kcal/mol
(Table 1, entry 6). The most stable CRM1/lactone complex was
observed for compound 10d, with the calculated binding energy to
CRM1 of ꢀ7.72 kcal/mol, which differentiates it significantly from
all other studied compounds.
Scheme 2. Synthesis of (ꢀ)-Massoailactone, 1.
diols 9e and 9e0 was obtained in a 1.2 to 1 ratio. Further oxidation of
9e gave the corresponding lactone 10e in good yield (Scheme 4).
All the compounds were characterized by 1H and 13C and HRMS.
Purity of all compounds was ꢂ95%.
2.2. Chemistry
2.3. Antiproliferative activity
The data obtained from the molecular docking studies prompted
us to synthesize the target compounds in order to evaluate their
in vitro cytotoxicity. Thus, a stereodefined vinyl telluride was used
to assembly the Z double bond present in (ꢀ)-Massoialactone. Thus,
propargyl alcohol 2 was converted into its TIPS [25] derivative 3,
and subjected to hydrotelluration conditions to yield the corre-
sponding vinyl tellurides 4 and 5 in a 9:1 ratio [26], being the two
regioisomers easily separated by flash column chromatography.
The regioisomeric ratio was determined by 1H NMR and confirmed
by 125Te NMR [27] and gas chromatography (Scheme 1).
The vinyl telluride 4 was then converted into the corresponding
Z higher order vinyl cyanocuprate [28] by the reaction with (2-Th)
BuCu(CN)Li2 followed by capture with epoxide 6. Subsequent
treatment with TBAF in THF [29] gave the corresponding 1,5-diol 7
in 75% overall yield after purification by chromatographic column.
Further oxidation of 7 with BAIB and a catalytic amount of TEMPO
following Forsyth protocol [30] gave (ꢀ)-Massoialactone, 1 in 70%
yield (Scheme 2).
It is known that different cell lines display different sensitivities
toward a cytotoxic compound. In this way, (ꢀ)-Massoailactone, 1
and lactones 10aee were submitted to the MTT assay [31] for the
evaluation of their cytotoxic effects on MCF-7 (human breast
adenocarcinoma), HT-29 (human colon adenocarcinoma), and NCI-
H292 (human lung carcinoma) cell lines. Some of the most active
compounds were also tested on HL-60 (human pro-myelocytic
leukemia), K562 (human erythromyeloblastoid leukemia).
Analogues were first screened at a 25 mg/mL initial concentra-
tion and the samples with growth inhibition over 90% were used to
determine the full dose response screening and IC50 determination.
The synthesized compounds were then screened at 25 mg/mL and
the samples with growth inhibition over 90% were used to deter-
mine the IC50 values.
(ꢀ)-Massoilactone, 1 displayed moderate cytotoxic activity
against all tested cancer cell lines, being more active against NCI-
H292 and HL-60 cancer cells lines (Table 2, entry 1). For analogue
10a, no antiproliferative activity was found demonstrating that the
Compared to other previously described methodologies, the
synthesis of (ꢀ)-Massoialactone 1, using a vinyl telluride as a pre-
cursor showed to be convergent and efficient while the Z double
bond and the stereocenter present in the natural product were
installed in one step. (ꢀ)-Massoialactone 1, was obtained in 52%
overall yield after three sequential steps.
presence of a hydrophobic segment, together with the
a,b-unsat-
urated -lactone group, is important for the antiproliferative ac-
d
tivity (Table 2, entry 2). This result corroborates with the values
obtained from the docking analysis, where analogue 10a exhibited
a higher binding energy to CRM1. This result was previously
observed for fostriecin [32].
The strategy was then applied for the synthesis of compounds
10aee. Thus, transmetalation of vinyl telluride 4 with (2-Th)
BuCu(CN)Li2 followed by the capture of the mixed cuprate with
epoxides 8aed and deprotection gave the corresponding 1,5-diols
Analogues 10b and 10c, which possess a side chain with a ter-
minal double bond, were also tested, but only 10c displayed mod-
erate cytotoxicity, confirming the previous docking study, which
indicated that the presence of an electronegative atom would in-
crease the potency of the analogue (Table 2, entries 3 and 4). It is
also known for cytostatin that the presence of the triene moiety is
not essential for the in vitro inhibition.
9aed which were oxidized to the corresponding
-lactones 10aed in good yields (Scheme 3).
In all cases, the lactones corresponding from the attack to the
a,b-unsaturated
d
less-substituted carbon atom in epoxides 8aed were obtained
exclusively. The only exception was observed when styrene oxide,
8e was used. In this case, a separable mixture of the regioisomeric
For all tested compounds, the analogues which possess an ar-
omatic ring in the side chain displayed better cytotoxic activities
against some of the tested cell lines (Table 2, entries 5 and 6).
Compound 10e exhibited good cytotoxic activity against lung can-
cer cells (NCI-H292) (Table 2, entry 6). Noteworthy, analogue 10d
displayed a good cytotoxic activity against all tested cell lines
(Table 2, entry 5), including human chronic myelogenous (CML)
leukemia cell line (K562), which is derived from pleural effusion of
a patient in the acute phase of CML and expresses the BCR-ABL
protein [33]. This protein confers resistance to apoptosis induc-
tion by a number of agents and conditions [34].
From Table 2, it can be observed that the results are in accor-
dance to those obtained from the docking analysis, once analogues
10a and 10b exhibited higher binding energies to CRM1 when
Scheme 1. Synthesis of Vinyl Telluride 4.

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M.E.S.B. Barros et al. / European Journal of Medicinal Chemistry 76 (2014) 291e300
Reagents and conditions: (i) (2-Th)BuCu(CN)Li2,THF, 25oC, 1 h; then 8a-d, -78 to 25oC, 2h; (ii) TBAF,
THF, 25oC, 3 h; (iii) BAIB, TEMPO, CH2Cl2, 25oC, 3h.
Scheme 3. Synthesis of a,b-unsaturated d-lactones 10aed.
compared to analogues 10d and 10e.In the same way, analogues
10a and 10b exhibited lower antiproliferative activities when
compared to analogues 10d and 10e.
The lack of commercial availability of chiral epoxides (8aee)
used for the synthesis of the a,b-unsaturated d-lactones makes the
synthesis of individual enantiomers difficult. In this way, the
binding patterns of both enantiomers of analogue 10d were inde-
pendently evaluated by docking analysis.
2.4. Anti-inflammatory activity
It is known that bacterial endotoxins, such as lipopolysaccha-
rides (LPS) activate macrophages leading to the production nitric
oxide, [35] an important pro-inflammatory mediator associated
with the activation of T lymphocytes [36]. LPS promotes activation
of Nuclear Factor kappa B (NF-kB) in macrophages, stimulating the
production of NO and pro-inflammatory cytokines. Thus, reduction
Thus, for the R-10d isomer, the approach to CRM1 occurs
initially by two intermolecular interactions: between LYS548 and
LYS579 with the carbonyl oxygen of lactone and, between LYS579
and the oxygen present in the lactone ring, positioning the double
of NO levels can be related to the inhibition of activation of nuclear
transcription factor kB, which regulates the expression of inducible
nitric oxide synthase (iNOS) and genes related to the production of
cytokines [37].
The synthesized lactones 10bed were then evaluated for in vitro
anti-inflammatory activity using LPS-stimulated murine peritoneal
macrophages. First, the cytotoxicity of lactones to these cells was
evaluated in order to avoid the use of cytotoxic concentrations for
analysis of anti-inflammatory effect (Table 3).
ꢀ
bond 3.65 A away from CYS539 (Fig. 2(a)). On the other hand, the
S-10d isomer fits into the hydrophobic region with both oxygen
atoms positioned toward inside the cavity, with the aromatic ring
accommodated in the hydrophobic region of MET556, positioning
ꢀ
the double bond 3.66 A away from CYS539, also resulting in the loss
of LYS548 and LYS579 interactions observed for the R-isomer. Using
this approach it was observed that the energy required to accom-
modate the R-10d isomer into the CRM1 cavity is about
0.2 Kcal molꢀ1 higher than the corresponding S-10d isomer, indi-
cating no enantiomer preference.
It is worth also to note that the lactone ring of LMB makes a
covalent bond with CYS539 of CRM1, the same bonding pattern
observed in both R and S enantiomers of 10d.
Superposition of compound 10d to LMB reveals a complemen-
tary fit into the hydrophobic binding grove of the export receptor as
this compound is expected to bind covalently to CRM1 with the
side chain mimicking the hydrophobic part of LMB (Fig. 3).
It was observed that the synthesized a,b-unsaturated d-lactones
affected cell viability in a dose-dependent manner. From Table 3 it
can be observed that the cytotoxic effect of lactones 10c and 10d at
the concentration of 3.1 mg/mL was weak. Conversely, treatment at
higher concentrations resulted in a lower percentage of viable cells
and thus the lowest concentration was selected for the next assay.
Both lactones 10c and 10d at a concentration of 3.1 mg/mL were able
to reduce the nitric oxide production by macrophages stimulated
with LPS (Table 4).
These results indicate that the detected in vitro anti-
inflammatory activity of 10c and 10d is at least in part due to the
regulation of NO production.
Reagents and conditions: (i) (2-Th)BuCu(CN)Li2,THF, 25oC, 1 h; then 8e, -78 to 25oC, 2h; (ii) TBAF,
THF, 25oC, 3 h; (iii) chromatography; (iv) BAIB, TEMPO, CH2Cl2, 25oC, 3h.
Scheme 4. Synthesis of a,b-unsaturated d-lactone 10e.

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295
Table 2
IC50 values for 1 and analogs 10aee.
IC50, confidence intervals 95% (m )
g mLꢀ1
MCF-7
60.0
NCI-H292
HT-29
Hl-60
K562
20.2
1
2
3
4
11.3
22.6
16.0
1
>100
>100
44.6
>100
>100
16.6
>100
>100
18.4
NT
NT
10a
NT
NT
10b
25.5
50.0
10c
5
6
22.5
22.9
0.8
4.4
5.4
2.9
10d
9.1
10.9
NT
13.2
0.03
8.9
7
DOXa
0.34
0.02
0.26
10e
a
Doxorubicin (DOX) was the positive control; NT, not tested.
Fig. 2. Lower energy (Kcal molꢀ1) molecular fit for (a) R-10d and (b) S-10d isomers.
The numbers indicate the distance (A) to the aminoacid residues in the fitting process.
TNF-
[38]. Thus, the reduction in NO levels could be attributed to the
reduction in the levels of TNF- . Table 5 shows the data from
measurement of cytokine production. Lactone 10d promoted sta-
tistically significant reduction (p < 0.05) in the levels of TNF-
released by LPS-stimulated macrophages (Table 5, entry 2). A
a is largely related to LPS-induced nitric oxide production
ꢀ
a
natural compounds suggesting that substantially altered analogues
may retain their properties.
a
smaller effect in the production of TNF-a was observed for lactone
10c (Table 5, entry 1).
4. Experimental section
The reported anti-inflammatory results may be related to inhi-
bition of activation of NF- B, which is generally followed by in-
crease in NO, TNF- and other cytokines levels, however further
1H and 13C NMR data were recorded at 300 and 75 MHz,
respectively, using a Varian UNITY PLUS spectrometer. NMR
k
a
studies should be conducted to confirm this hypothesis.
chemical shifts are reported as delta (d) units in parts per million
(ppm) relative to residual CDCl3 Coupling constants (J) were re-
ported in hertz (Hz). 125Te NMR data were obtained at 94.6 MHz
using diphenyl ditelluride as an external reference (422.0 ppm).
Typical parameters were as follows: acquisition time equal to
0.64 s, pulse of 45ꢃ, spectral window of 43.9 kHz; and line broad-
ening equal to 5.0 Hz. Low resolution mass spectra were obtained
using a Shimadzu QP-5050A Spectrometer (70 eV) using helium 4.5
3. Conclusion
The binding interactions between (ꢀ)-Massoialactone and
related a,b-unsaturated d-lactones to CRM1 were evaluate by mo-
lecular docking. The evaluated compounds were then synthesized
and tested against five cancer cell lines. Among all derivatives,
compound 10d was the most active against the tested cancer cell
lines, and this result is in accordance to molecular docking calcu-
lations. Compound 10d also demonstrated in vitro anti-
inflammatory activity on LPS-stimulated macrophages by regu-
lating the production of cytokines and NO. From a broader
perspective, the synthesized lactones were able to mimic the “core”
functional groups required for the biological activity of their parent
as a carrier gas and a DB-5 column (30 m ꢁ 0.25 m
m). High reso-
lution mass spectra were obtained by the electro spray ionization
time-of-flight (ESI-TOF) mode on a Bruker Micro TofIc Bruker Dal-
tonics mass spectrometer.
Infra-red spectra were recorded using FT/IR spectrometer
Bruker IFS 66 and the samples were prepared as thin films on salt
plates or as KBr pellets.

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M.E.S.B. Barros et al. / European Journal of Medicinal Chemistry 76 (2014) 291e300
Table 4
Effect of
a,b-unsaturated d-lactones 10c and 10d on nitric oxide production by murine
macrophages stimulated with LPS.
Entry
Concentration (
m
g mLꢀ1
)
NO (mM)
1
2
3
4
10c
10d
LPS
Control
3.1
3.1
1.0
e
2.7 ꢄ 0.05*
5.2 ꢄ 0.04*
19.2 ꢄ 0.06*
2.8 ꢄ 0.13
Data are presented as mean ꢄ standard deviation of three independent experi-
ments. *p < 0.05 compared to control (cells in medium culture only) by ANOVA
followed by NewmaneKeuls test.
4H, 2 ꢁ CH2), 1.83e1.61 (m, 4H, 2 ꢁ CH2), 1.44e1.33 (m, 4H,
2 ꢁ CH2), 0.90 (t, J ¼ 7.50 Hz, 6H, 2 ꢁ CH3); 13C NMR (75 MHz,
CDCl3)
(2 ꢁ CH3).
d
35.3 (2 ꢁ CH2), 24.2 (2 ꢁ CH2), 13.5 (2 ꢁ CH2), 4.0
4.2. Preparation of triisopropyl(prop-2-ynyloxy)silane (3)
To a round-bottomed flask under argon was added CH2Cl2
(30 mL), imidazole (1.70 g, 25 mmol), and propargyl alcohol (0.56 g,
0.58 mL, 10 mmol) the mixture was cooled to 0 ꢃC and TIPSCl
(2.30 g, 2.55 mL, 12 mmol) was slowly added. The mixture was
stirred for 12 h, diluted with CH2Cl2 (20 mL) and quenched with
water (20 mL). The organic phase was washed with 3% HCl (10 mL),
saturated NaHCO3 (20 mL) and finally water. The organic phase was
then dried over MgSO4, filtered and concentrated in vacuo. The pure
silyl ether was distilled from the residue under reduced pressure
(bp 110 ꢃC, 20 mm Hg) to yield 2.0 g (95%) of compound 3. 1H NMR
Fig. 3. Lower energy (Kcal molꢀ1) molecular fit superposition of compound 10d and
(300 MHz, CDCl3)
d
4.35 (d, J ¼ 2.4 Hz, 2H, CH2), 2.35 (t, J ¼ 2.7 Hz,
Leptomycin B binding to CRM1.
1H, CCH), 1.10e1.00 (m, 3H, 3 ꢁ CH, 18H, 6 ꢁ CH3); 13C NMR
(75 MHz, CDCl3)
(CH2), 17.5 (6 ꢁ CH3), 12.0 (3 ꢁ CH).
d ppm 81.5 (CH^CCH2), 72.3 (CH^CCH2), 51.5
4.1. Preparation of dibutylditelluride (BuTeTeBu)
A 2 L round-bottomed flask was flamed dry and equipped with
a 250 mL pressure equalized dropping funnel was charged with
tellurium metal (20.1 g, 157 mmol) [dried at 85 ꢃC prior to use] and
dry THF (1 L) was cooled to 0 ꢃC. The addition funnel was charged
with n-butyllithium (180 mmol, 72 mL of a 2.5 M solution in
bexanes). The n-butyllithium was added dropwise. After the
addition was complete, the ice bath was removed and the reaction
mixture was stirred at room temperature for 60 min. A saturated
solution of ammonium chloride (250 mL) was then slowly added.
The reaction was stirred at room temperature for about 3 h while
open to the atmosphere (O2). The organic layer was isolated and
the aqueous layer was extracted with EtOAc (2 ꢁ 150 mL). The
combined organic phases were dried over MgSO4 and filtered
through a pad of Celite. Concentration in vacuo provided 50.7 g
(87%) of dibutylditelluride as a red oil which was used directly
4.3. Preparation of (Z)-(3-(butyltellanyl)allyloxy)triiso-propylsilane
(4)
3 (19.0 g, 90 mmol) and dibutylditelluride (16.8 g, 45 mmol)
were dissolved in absolute ethanol (100 mL) at room temperature.
Finely powdered sodium borohydride was added in portions to the
above solution. Additional sodium borohydride was added as
necessary to maintain a yellow color (indicative of the butyltel-
lurolate anion). The solution was heated to reflux for 5 h and cooled
to room temperature. The reaction mixture was then poured into a
saturated solution of NaHCO3 (200 mL) and diluted with EtOAc
(200 mL). The organic layer was isolated and washed with H2O
(500 mL) and brine (500 mL) before drying over MgSO4. The
organic phase was filtered and concentrated in vacuo. Silica gel
chromatography using hexanes provided 30.6 g, (85%) of the title
without further purification. IR (KBr pellet, cmꢀ1
)
nmax 2955, 2921,
compound as a yellow oil. IR (KBr pellet, cmꢀ1
1462, 1095, 918; 1H NMR (300 MHz, CDCl3)
1.5 Hz, 1H, TeCH]CH), 6.40 (dt, J ¼ 9.9 Hz, 5.1 Hz, 1H, TeCH]CH),
) nmax 2941, 2865,
6.70 (dt, J ¼ 9.9 Hz,
2868, 1457, 1175; 1H NMR (300 MHz, CDCl3)
d
3.12 (t, J ¼ 7.80 Hz,
d
Table 3
Effect of a,b-unsaturated d-lactones 10bee on the viability of LPS-stimulated peri-
toneal macrophages.
Table 5
Effect of
a,b-unsaturated d-lactones 10c and 10d on TNF-a production by murine
macrophages stimulated with LPS.
Entry
Concentration (
m
g mLꢀ1)
3.1
6.2
12.5
25.0
Entry
Concentration (
m
g mLꢀ1
)
TNF-a (pg/mL)
1
2
3
4
10b
10c
10d
10e
57
100
93
45.4
77.2
47.3
30.9
19.7
51.1
0
2.5
7.7
0
1
2
3
4
10c
10d
LPS
Control
3.1
3.1
1.0
e
210.0 ꢄ 7.7*
112.4 ꢄ 9.8*
274.4 ꢄ 10.6*
57.5 ꢄ 5.9
34.5
1.0
7.4
The cytotoxicity was evaluated by MTT assay after 24 h incubation of peritoneal
macrophages cells with 3.1e25.0 g/mL 10bee and/or LPS. The values represent
mean ꢄ SD of three independent experiments (n ¼ 12).
Data are presented as mean ꢄ standard deviation of three independent experi-
ments. *p < 0.05 compared to control (cells in medium culture only) by ANOVA
followed by NewmaneKeuls test.
m

M.E.S.B. Barros et al. / European Journal of Medicinal Chemistry 76 (2014) 291e300
297
4.20 (dd, J ¼ 5.1 Hz, 1.5 Hz, 2H, CH]CHCH2), 2.75 (t, J ¼ 7.8 Hz, 2H,
4.4.2. (Z)-Hept-2-ene-1,5-diol (9a)
CH2), 1.93e1.62 (m, 2H, CH2), 1.45e1.22 (m, 2H, CH2), 1.20e1.05
(m, 3H, 3 ꢁ CH, 18H, 6 ꢁ CH3), 0.95 (t, J ¼ 7.50 Hz, 3H, CH3); 13C
Isolated as a yellow oil, 0.91 g; (70%); IR (KBr pellet, cmꢀ1
)
nmax
3329 (OH), 3019, 2963, 2932, 2877, 1461, 1113, 1013; 1H NMR
(300 MHz, CDCl3) d 5.75e5.70 (m, 1H, CH]CH), 5.60e5.50 (m, 1H,
NMR (75 MHz, CDCl3)
d
138.0 (TeCH]CH), 102.0(TeCH]CH), 65.5
(CH]CHCH2), 34.0 (CH2), 25.0 (CH2), 17.7 (6 ꢁ CHCH3), 17.5 (CH2),
CH]CH), 4.10 (dd, J ¼ 12.3, 7.2 Hz, 1H, CH2CH]CH), 4.00 (dd,
J ¼ 12.3, 7.2 Hz,1H, CH2CH]CH), 3.90 (br. s., 2H, 2 ꢁ OH), 3.50e3.45
(m, 1H, CHOH), 2.20 (t, J ¼ 7.5 Hz, 2H, CH]CHCH2), 1.40 (qui,
J ¼ 7.5 Hz, 2H, CH2CH3), 0.90 (t, J ¼ 7.5 Hz, 3H, CH3); 13C NMR
13.0 (CH3), 12.0 (3 ꢁ CHCH3); 125Te NMR (94.6 MHz, CDCl3)
d 298.9;
GCMS (EI, Rel. Int. %) m/z 400 ([Mþ], 6), 357 (83), 245 (41), 227 (12),
213 (29), 169 (100), 157 (24), 127 (60), 87 (10), 57 (7); HRMS (ESI,
MeOH:H2O) calc for C16H34OSiTe [M þ H]þ, 401.1519, found
400.9330.
(75 MHz, CDCl3)
d 131.0 (CH]CH), 129.0 (CH]CH), 72.0 (CHOH),
57.0 (CH2CH]CH), 34.5 (CH]CHCH2), 30.0 (CH2CH3), 10.0
(CH2CH3); GCMS (EI, Rel. Int. %) m/z 130 ([Mþ], 1), 83 (8), 57 (33), 54
(100), 41 (18); HRMS (ESI, MeOH:H2O) calcd for C7H14O2Na
[M þ Na]þ, 153.0892, found 153.0899.
4.4. General procedure for the synthesis of 1,5-diols (7), (9aee) and
(9e0) from the reaction of (4) with (2-Th)BuCu(CN)Li2 system and
epoxides (6) or (8aee) followed by deprotection
4.4.3. (Z)-Nona-2,8-diene-1,5-diol (9b)
Isolated as a yellow oil, 1.11 g; (71%); IR (KBr pellet, cmꢀ1
)
nmax
3329 (OH), 2933, 1640, 1436, 1076, 1007, 911, 861; 1H NMR
(300 MHz, CDCl3) 5.95e5.70 (m,1H, CH]CH,1H, CH]CH2), 5.65e
To a flask equipped with a stirring bar and a rubber septum,
flame-dried under argon atmosphere was added anhydrous THF
(10 mL) and distilled thiophene (1.05 g, 12.5 mmol). The solution
was cooled to ꢀ78 ꢃC and n-butyllithium in hexanes (1.40 M,
9.0 mL, 12.5 mmol) was added dropwise. The resulting light-yellow
solution was warmed to ꢀ40 ꢃC and kept for 20 min. After that, this
solution was transferred via cannula to a CuCN (0.89 g, 10 mmol)
suspension in THF cooled at ꢀ78 ꢃC. At the end of the addition, the
acetoneedry ice bath was exchanged for an ice bath. After 5 min the
flask was again placed in a dry iceeacetone bath and n-butyllithium
in hexanes (1.40 M, 7.10 mL, 10 mmol) was added dropwise. The
solution was maintained at this temperature for 15 min. After that,
the solution was heated at 0 ꢃC and the vinylic telluride 4 (4.20 g,
10.5 mmol) dissolved in THF (10 mL) was added. After being stirred
for 1 h at room temperature, the mixture was cooled to ꢀ78 ꢃC and
the appropriate epoxide 6 or 8aee (10 mmol) in THF (10 mL) was
added. The reaction mixture was warmed to 0 ꢃC. After 3 h at 0 ꢃC, it
was warmed to ambient temperature and stirred for an additional
1 h. The reaction mixture was then cooled to ꢀ78 ꢃC and poured on
to a solution of saturated aqueous ammonium chloride and
concentrated aqueous ammonium hydroxide (9:1). The mixture
was stirred for 15 min while the temperature of the system was
allowed to rise. After that, the mixture was extracted with EtOAc
(2 ꢁ 60 mL). The organic layer was washed with brine (2 ꢁ 100 mL).
The combined organic layers were dried over MgSO4 and concen-
trated in vacuo. The crude product was dissolved in THF (5 mL) and
TBAF (10 mL, 1 M solution in THF, 10 mmol) was added dropwise.
The reaction was monitored by TLC. The reaction was then
quenched by the addition of a saturated solution of NH4Cl (10 mL).
The aqueous layer was extracted with EtOAc and the combined
organic phases were washed with brine, dried over MgSO4, filtered
and concentrated in vacuo. The crude product were purified by
chromatography on silica gel using 50:50 hexanes/EtOAc to yield
the corresponding 1,5-diols, 7, 9aee and 9e0.
d
5.50 (m, 1H, CH]CH), 5.00e4.95 (m, 2H, CH]CH2), 4.15 (dd,
J ¼ 12.3, 7.2 Hz, 1H, CH2CH]CH), 4.00 (dd, J ¼ 12.3, 6.6 Hz, 1H,
CH2CH]CH), 3.68e3.60 (m, 1H, CHOH), 3.25 (br. S, 2H, 2 ꢁ OH),
2.30e2.00 (m, 2H, CH]CHCH2, 2H, CH2CH]CH2), 1.60e1.50 (m,
2H, CH2CH2CH ¼ CH2); 13C NMR (75 MHz, CDCl3)
d 138.0 (CH]
CH2), 131.0 (CH]CH), 129.5 (CH]CH), 115.0 (CH]CH2), 70.0
(CHOH), 57.5 (CH2CH]CH), 36.0 (CHOHCH2), 35.0 (CHOHCH2CH2),
30.0 (CH]CHCH2), GCMS (EI, Rel. Int. %) m/z 138 (1), 83 (14), 79 (6),
71 (10), 67 (14), 54 (100), 41 (37); HRMS (ESI, MeOH:H2O) calcd for
C9H16O2Na [M þ Na]þ, 179.1048; found 179.1051.
4.4.4. (Z)-6-(allyloxy)hex-2-ene-1,5-diol (9c)
Isolated as a yellow oil, 1.25 g; (73%); IR (KBr pellet, cmꢀ1
)
nmax
3355 (OH), 2865, 1647, 1423, 1087, 1006, 930, 668; 1H NMR
(300 MHz, CDCl3) 5.90e5.72 (m,1H, CH]CH,1H, CH]CH2), 5.60e
d
5.50 (m, 1H, CH]CH), 5.25 (ddd, J ¼ 17.0, 3.0, 1.5 Hz, 1H, CH]CH2),
5.15 (ddd, J ¼ 10.8, 3.0, 1.5 Hz, 1H, CH]CH2), 4.13 (dd, J ¼ 12.3,
7.5 Hz, 1H, CH2CH]CH), 4.00 (dd, J ¼ 12.3, 7.5 Hz, 1H, CH2CH]CH),
3.98 (ddd, J ¼ 7.2, 3.0, 1.5 Hz, 2H, CH2CH]CH2), 3.80e3.78 (m, 1H,
CHOH), 3.41e3.30 (m, 2H, CHOHCH2, 2H, 2 ꢁ OH), 2.35e2.20 (m,
2H, CH2CH]CH); 13C NMR (75 MHz, CDCl3)
d 134.0 (CH]CH2),
131.5 (CH]CH), 128.8 (CH]CH), 117.5 (CH]CH2), 73.8 (CHOHCH2),
72.0 (CH2CH]CH2), 69.0 (CHOH), 57.5 (CH2CH]CH), 31.0 (CH]
CHCH2); GCMS (EI, Rel. Int. %) m/z 136 (1), 101 (5), 83 (31), 55 (56),
54 (48), 41 (100); HRMS (ESI, MeOH:H2O) calcd for C9H16O3Na
[M þ Na]þ,195.0997; found 195.0998.
4.4.5. (Z)-6-Phenoxyhex-2-ene-1,5-diol (9d)
Isolated as a colorless oil; 1.45 g; (70%); IR (KBr pellet, cmꢀ1
)
nmax 3330 (OH), 2926, 2875, 1598, 1495,1292, 1244, 1078, 754; 1H
NMR (300 MHz, CDCl3)
d
7.35e7.25 (m, 2H, 2 ꢁ AreCH), 7.00e6.90
(m, 3H, 3 ꢁ AreCH), 5.95e5.82 (m, 1H, CH]CH), 5.72e5.60 (m, 1H,
CH]CH), 4.24e4.20 (m, 1H, CHOH), 4.15e4.01 (m, 2H, CHOHCH2),
4.00e3.88 (m, 2H, CH2CH]CH), 3.10 (br. s., 2H, 2 ꢁ OH), 2.55e2.35
4.4.1. (R,Z)-dec-2-ene-1,5-diol (7)
Isolated as yellow oil, 0.65 g (75%). [
(KBr pellet, cmꢀ1
721; 1H NMR (300 MHz, CDCl3)
a
]
D
20 þ9.5 (c 1.00, CHCl3); IR
(m, 2H, CH]CHCH2); 13C NMR 158.5 (Cq-Ar),
d (75 MHz, CDCl3) d
)
nmax 3329 (OH), 2921, 2843, 1661, 1472, 1011, 867,
131.6 (CH]CH), 129.5 (CH]CH), 128.0 (2 ꢁ CHeAr), 121.0 (CHeAr),
114.5 (2 ꢁ CHeAr), 71.0 (CHOHCH2), 69.0 (CHOH), 57.5 (CH2CH]
CH), 31.0 (CH]CHCH2); GC/MS (EI, Rel. Int. %) m/z 208 ([Mþ], 3),
154, 136 (20), 119 (12), 108 (35), 94 (100), 77 (45), 65 (18), 55 (44),
51 (19), 43 (38), 41 (26); HRMS (ESI, MeOH:H2O) calcd for
d
5.92e5.82 (m, 1H, CH]CH), 5.65e
5.56 (m, 1H, CH]CH), 4.15 (dd, J ¼ 12.0, 7.5 Hz, 1H, CH2CH]CH),
4.00 (dd, J ¼ 12.3, 6.6 Hz, 1H, CH2CH]CH), 3.64e3.60 (m, 1H,
CHOH), 2.60 (br. s, 2H, 2 ꢁ OH), 2.30e2.20 (m, 2H, CH]CHCH2),
1.50e1.40 (m, 2H, CHOHCH2), 1.35e1.25 (m, 6H, 3 ꢁ CH2), 0.90 (t,
C
12H16O3Na [M þ Na]þ, 231.0997; found, 231.0991.
J ¼ 6.9 Hz, 3H, CH3); 13C NMR (75 MHz, CDCl3)
d 132.0 (CH]CH),
130.0 (CH]CH), 70.5 (CHOH), 57.0 (CH2CH]CH), 36.6 (CH2), 34.5
(CH2), 32.0 (CH2), 25.2 (CH2), 22.0 (CH2), 13.8 (CH3), GCeMS (EI, Rel.
Int. %) m/z 154 (1), 99 (12), 55 (35), 54 (100), 43 (14), 41 (12); HRMS
(ESI, MeOH:H2O) calcd for C10H20O2Na [M þ Na]þ, 195.1361; found
195.1364.
4.4.6. (Z)-5-Phenylpent-2-ene-1,5-diol (9e)
Isolated as a yellow oil, 0.62 g; (35%); IR (KBr pellet, cmꢀ1
) nmax
3344 (OH), 3062, 2923, 1712, 1493, 1026, 760, 733, 700; 1H NMR
(300 MHz, CDCl3)
CH]CH), 5.55 (m, 1H, CH]CH), 4.65 (dd, J ¼ 8.1, 4.5 Hz, 1H, CHOH),
d
7.30e7.25 (m, 5H, 5 ꢁ AreCH), 5.77 (m, 1H,

298
M.E.S.B. Barros et al. / European Journal of Medicinal Chemistry 76 (2014) 291e300
4.00 (dd, J ¼ 12.3, 7.5 Hz, 1H, CH2CH]CH), 3.90 (dd, J ¼ 12.3, 6.6 Hz,
1H, CH2CH]CH), 3.00 (br. s., 2H, 2 ꢁ OH), 2.60e2.55 (m, 1H, CH]
CHCH2), 2.45e2.40 (m, 1H, CH]CHCH2); 13C NMR (75 MHz, CDCl3)
HRMS (ESI, MeOH:H2O) calcd for C7H10O2Na [M þ Na]þ, 149.0579;
found 149.0230.
d
144.0 (Cq-Ar), 131.5 (CH]CH), 129.0 (CH]CH), 128.5 (2 ꢁ CHeAr),
4.5.3. 6-(But-3-enyl)-5,6-dihydro-2H-pyran-2-one (10b)
127.5 (CHeAr), 125.8 (2 ꢁ CHeAr), 72.8 (CHOH), 57.5 (CH2CH]CH),
37.0 (CH]CH CH2); GCMS (EI, Rel. Int. %) m/z 178 ([Mþ], 1), 107 (76),
106 (13), 105 (100), 79 (91), 78 (12), 77 (66), 54 (93), 51 (20); HRMS
(ESI, MeOH:H2O) calcd for C11H14O2Na [M þ Na]þ 201.0892; found
201.0896.
Isolated as a colorless oil, 0.25 g, (65%); IR (thin film, cmꢀ1
)
nmax
1716 (C]O), 1388, 1065, 1039, 996, 955, 864, 817; 1H NMR
(300 MHz, CDCl3)
d
6.90 (ddd, J ¼ 9.6, 5.1, 3.9 Hz, 1H, CH]CHCH2),
6.00 (dt, J ¼ 9.6, 1.8 Hz, 1H, CH]CHCH2), 5.85e5.72 (m, 1H, CH]
CH2), 5.10e5.00 (m, 2H, CH]CH2), 4.50e4.40 (m, 1H, CH), 2.35e
2.20 (m, 4H, 2 ꢁ CH2);13C NMR (75 MHz, CDCl3)
d 164.5 (C]O),
4.4.7. (Z)-4-Phenylpent-2-ene-1,5-diol (9e0)
145.0 (CH]CH), 137.0 (CH]CH2), 121.5 (CH]CH), 115.8 (CH]CH2),
77.0 (CH2CHO), 34.0 (CH2CHO), 29.5 (CH2), 28.8 (CH2); GCMS (EI,
Rel. Int. %) m/z 152 ([Mþ], 1), 110 (17), 97 (85), 69 (53), 68 (100), 67
(52), 55 (34), 42 (20), 41 (79), 40 (34); HRMS (ESI, MeOH:H2O) calcd
for C9H12O2Na [M þ Na]þ, 175.0735; found 175.0729.
Isolated as a yellow oil, 0.53 g; (30%); IR (KBr pellet, cmꢀ1
)
nmax
3330 (OH), 2955, 2924, 2870, 1492, 1453, 1037, 699; 1H NMR
(300 MHz, CDCl3)
d
7.35e7.30 (m, 2H, 2 ꢁ AreCH), 7.20e7.28 (m,
3H, 3 ꢁ AreCH), 5.98e5.90 (m, 1H, CH]CH), 5.85e5.78 (m, 1H,
CH]CH), 4.35 (ddd, J ¼ 12.4, 7.4, 1.4 Hz, 1H, CH2CH]CH), 4.10 (ddd,
J ¼ 12.4, 6.3, 0.8 Hz, 1H, CH2CH]CH), 3.95e3.80 (m, 2H, CH2OH),
3.75e3.68 (m, 1H, CH), 2.15 (br. s., 2H, 2 ꢁ OH); 13C NMR (75 MHz,
4.5.4. 6-(Allyloxymethyl)-5,6-dihydro-2H-pyran-2-one (10c)
Isolated as a colorless oil, 0.31 g, (75%); IR (thin film, cmꢀ1
)
nmax
3524, 3079, 2914, 2867,1722 (C]O),1423,1249,130,1051, 848, 663;
1H NMR (300 MHz, CDCl3)
CDCl3)
d
140.8 (Cq-Ar), 133.5 (CH]CH), 131.0 (CH]CH), 129.0
d
6.90 (ddd, J ¼ 9.6, 6.0, 2.7 Hz, 1H, CH]
(2 ꢁ CHeAr), 127.5 (2 ꢁ CHeAr), 127.0 (CHeAr), 66.5 (CH2), 58.0
(CH2CH]CH), 46.5 (CH), GCMS (EI, Rel. Int. %) m/z 169 (1), 130
(100), 129 (75), 128 (29), 115 (32), 91 (70), 77 (18), 51 (16), 41 (21);
HRMS (ESI, MeOH:H2O) calcd for C11H14O2Na [M þ Na]þ, 201.0892;
found 201.0883.
CHCH2), 5.98 (ddd, J ¼ 9.6, 2.4, 0.9 Hz, 1H, CH]CHCH2), 5.90e5.80
(m, 1H, CH]CH2), 5.28e5.15 (m, 2H, CH]CH2), 4.60e4.50 (m,
1H, CH), 4.00 (dt, J ¼ 5.7, 1.2 Hz, 2H, CH2CH]CH2), 3.60 (d,
J ¼ 4.5 Hz, 2H, CH2), 2.60e2.30 (m, 1H, CH]CHCH2), 2.30e2.45 (m,
1H, CH]CHCH2); 13C NMR (75 MHz, CDCl3)
d 163.8 (C]O), 145.0
(CH]CH), 134.0 (CH]CH2), 121.0 (CH]CH), 117.5 (CH]CH2), 76.5
(CHOCH2OCH2), 72.5 (CH2CHCH2), 70.8 (CH2CHO), 26.0 (CH]
CHCH2); GCMS (EI, Rel. Int. %) m/z 169 ([M þ 1], 1), 154 (46), 126
(68), 97 (34), 81 (13), 69 (74), 55 (30), 43 (90), 41 (86), 40 (37);
HRMS (ESI, MeOH:H2O) calcd for C9H12O3Na [M þ Na]þ, 191.0684;
found 191.0680.
4.5. General procedure for the synthesis of
-lactones (1) and (10aee) from the reaction of 1,5-diols (7) and
(9aee) with TEMPO/BAIB
a,b-unsaturated
d
To a stirred solution of the appropriate diol7 or 9aee (2.5 mmol,
1 equiv) in CH2Cl2 (30 mL) was added bis-acetoxyiodobenzene
(BAIB) (2.5 g, 7.7 mmol, 3 equiv) and 2,2,6,6-tetramethyl-1-
piperidinyloxy (TEMPO) (0.08 g, 20 mol%) at room temperature.
After stirring for 3 h, the reaction mixture was quenched with a
saturated solution of Na2S2O3 (10 mL) and extracted with CH2Cl2
(2 ꢁ 25 mL). The combined organic extracts were washed with
saturated solutions of NaHCO3 (10 mL), NH4Cl (10 mL) and brine
(2 ꢁ 50 mL), dried over MgSO4, filtered and concentrated in vacuo.
The residue was purified by chromatography on silica gel using
100:0 to 90:10 (hexanes/EtOAc) to yield the lactones 1 and 10aee.
4.5.5. 6-(Phenoxymethyl)-5,6-dihydro-2H-pyran-2-one (10d)
Isolated as a white solid, 0.33 g, (65%); m.p 80e82 ꢃC; IR (KBr
pellet, cmꢀ1
)
nmax 1721 (C]O), 1599, 1495, 1386, 1238, 1087, 1044,
812, 756; 1H NMR (300 MHz, CDCl3)
d
7.29e7.14 (m, 2H, 2 ꢁ Are
CH), 6.95e6.80 (m, 3H, 3 ꢁ AreCH, 1H, CH]CHCH2), 6.00 (ddd,
J ¼ 9.6, 3.9, 2.2 Hz, 1H, CH]CHCH2), 4.78e4.68 (m, 1H, CH), 4.15e
4.00 (m, 2H, CH2), 2.65e2.40 (m, 2H, CH]CHCH2); 13C NMR
(75 MHz, CDCl3) d
163.5 (C]O),158.0 (Cq-Ar),145.0 (CH]CH),129.5
(2 ꢁ CHeAr), 121.5 (CH]CH), 121.0 (CHeAr), 114.4 (CHeAr), 75.5
(CH2CHO), 68.0 (CH2OeAr), 26.0 (CH2), GCMS (EI, Rel. Int. %) m/z
204 ([Mþ], 43), 111 (28), 110 (36), 107 (24), 97 (100), 94 (33), 83 (15),
81 (16), 79 (17), 77 (67), 69 (56), 55 (25), 43 (70), 41 (59); HRMS
(ESI, MeOH:H2O) calcd for C12H12O3Na [M þ Na]þ, 227.0684; found
227.0672.
4.5.1. (ꢀ)-Massoialactone (1)
20
Isolated as a colorless oil, 0.28 g, (70%). [
a]
ꢀ 115.6 (c 1.00,
D
CHCl3); IR (thin film, cmꢀ1
812, 665; 1H NMR (300 MHz, CDCl3)
) nmax 2927, 2849, 1718, 1381, 1257, 1041,
d
6.80 (dd, J ¼ 9.6, 4.4 Hz, 1H,
CH]CHCH2), 5.95 (d, J ¼ 9.6 Hz, 1H, CH]CHCH2), 4.40e4.30 (m,
1H, CH), 2.30e2.25 (m, 2H, CH]CHCH2), 1.75e1.20 (m, 8 H,
4 ꢁ CH2), 0.85 (t, J ¼ 6 Hz, 3H, CH3); 13C NMR (75 MHz, CDCl3)
4.5.6. 6-Phenyl-5,6-dihydro-2H-pyran-2-one (10e)
Isolated as a colorless oil, 0.22 g, (50%); IR (thin film, cmꢀ1
)
nmax
1722 (C]O), 1454, 1382, 1246, 1061, 1022, 816, 760, 699; 1H NMR
(300 MHz, CDCl3)
d
164.0 (C]O), 144.8 (CH]CH), 121.0 (CH]CH), 77.5 (CH2CHO),
34.5 (CH]CHCH2), 31.5 (CH2), 30.0 (CH2), 24.5 (CH2), 22.0 (CH2),
13.5 (CH2); GCeMS (EI, Rel. Int. %) m/z 169 ([M þ 1], 2), 154 (41), 137
(23), 126 (62), 109 (42), 97 (37), 95 (20), 55 (28), 43 (89), 42 (29), 41
(83), 40 (34); HRMS (ESI, MeOH:H2O) calcd for C10H16O2Na
[M þ Na]þ, 191.1048; found 191.1045.
d
7.45e7.35 (m, 5H, 5 ꢁ AreCH), 7.00 (ddd,
J ¼ 10.0, 5.6, 3.2 Hz, 1H, CH]CHCH2), 6.15 (ddd, J ¼ 10.0, 2.4, 1.2 Hz,
1H, CH]CHCH2), 5.45 (dd, J ¼ 10.8, 5.2 Hz, 1H, CH), 2.65e2.60 (m,
2H, CH2); 13C NMR (75 MHz, CDCl3)
d 164.0 (C]O), 145.0 (CH]CH),
138.5 (Cq-Ar), 128.8 (2 ꢁ CHeAr), 128.5 (2 ꢁ AreCH), 126.0 (Are
CH), 121.8 (CH]CH), 79.0 (CH2CHO), 31.5 (CH2); GCMS (EI, Rel. Int.
%) m/z 174 ([Mþ], 17), 128 (5), 105 (9), 77 (16), 68 (100), 51 (14);
HRMS (ESI, MeOH:H2O) calcd for C11H10O2Na [M þ Na]þ, 197.0579;
found 197.0575.
4.5.2. 6-Ethyl-5,6-dihydro-2H-pyran-2-one (10a)
Isolated as a colorless oil, 0.24 g, (75%); IR (thin film, cmꢀ1
)
nmax
1714 (C]O),1251,1036, 865; 1H NMR (300 MHz, CDCl3)
d 6.88 (ddd,
J ¼ 9.6, 5.1, 3.3 Hz,1H, CH]CHCH2), 6.00 (dt, J ¼ 9.6,1.5 Hz,1H, CH]
CHCH2), 4.40e4.30 (m, 1H, CH), 2.35e2.30 (m, 2H, CH]CHCH2),
1.85e1.65 (m, 2H, CH2), 1.00 (t, J ¼ 7.2 Hz, 3H, CH3); 13C NMR
4.6. Antiproliferative activity
(75 MHz, CDCl3)
d
164.5 (C]O), 145.0 (CH]CH), 121.5 (CH]CH),
The antiproliferative activities of (ꢀ)-Massoialactone, 1 and
unsaturated -lactones 10aee were evaluated in the following
human cancer cells lines: HL-60 (pro-myelocytic leukemia), K562
a,b-
79.0 (CH2CHO), 30.0 (CH2), 28.0 (CH2), 9.0 (CH3); GCMS (EI, Rel. Int.
d
%) m/z 126 ([Mþ], 2), 97 (72), 69 (28), 68 (100), 41 (33), 40 (21);

M.E.S.B. Barros et al. / European Journal of Medicinal Chemistry 76 (2014) 291e300
299
(chronic myelogenous leukemia), HT-29 (colon carcinoma), NCI-
Acknowledgments
H292 (lung carcinoma) and MCF-7 (breast carcinoma) obtained
from Rio de Janeiro Cell Bank (RJ-Brazil). All cancer cells were
maintained in RPMI 1640 medium supplemented with 10% fetal
The authors gratefully acknowledge CNPq (484778/2011-0),
FACEPE (APQ-1402-1.06/10), FACEPE (PRONEX APQ-0859-1.06/08),
CAPES and INCT-INAMI for financial support. P.H.M.; M. E. S. B. B
and J.C.R.F. are thankful to CNPq for their fellowships.
bovine serum, 2 mM glutamine, 100 U/mL penicillin, 100 mg/mL
streptomycin at 37 ꢃC with 5% CO2. The cytotoxicity of all com-
pounds was tested using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-
diphenyl-2H-tetrazolium bromide (MTT) (Sigma Aldrich Co., St.
Louis, MO/USA) reduction assay. For all experiments, tumor cells
were plated in 96-well plates (105 cells/mL for adherent cells or
Appendix A. Supplementary data
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.ejmech.2014.02.013. These data include MOL
files and InChiKeys of the most important compounds described in
this article.
3 ꢁ 105 cells/mL for leukemias). Tested Compounds (0.1e25
mg/mL)
dissolved in DMSO 0.1% were added to each well and incubated for
72 h. Control groups received the same amount of DMSO. After 69 h
of treatment 25
mL of MTT (5 mg/mL) was added, 3 h later, the MTT
formazan product was dissolved in 100
mL of DMSO, and absor-
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