Synthesis and Cytotoxicity Studies of Stilbene Long-Chain Fatty Acid Conjugates

Article abstract of DOI:10.1021/acs.jnatprod.0c00027

A series of 16 conjugates of the tubulin polymerization inhibitor combretastatin A4 (CA-4) and other functionally related stilbene with four 18-carbon fatty acids, namely, stearic, oleic, linoleic, and linolenic acids, have been synthesized in good yields. These new derivatives have been evaluated against the KB-3-1 (human epidermoid carcinoma), NCI-H460 (human lung cancer), HEK293 (human embryonic kidney), and MCF-7 (human breast adenocarcinoma) cell lines for antiproliferative activity, with the exhibited cytotoxic activities comparable with those of CA-4 and colchicine. Compounds 22 and 23, CA-4 conjugates of linoleic and linolenic acids, respectively, were determined to have exhibited the most active in vitro assays, with compound 23 exhibiting very similar activity to the parent compound against the NCI-H460 cell line. Our studies further delineated the structurally required Z-geometry of the stilbene moiety and that conjugation of the less active E-stilbenes with the most active fatty acid had minimal or no improvement in their respective activities.

Full text of DOI:10.1021/acs.jnatprod.0c00027

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Synthesis and Cytotoxicity Studies of Stilbene Long-Chain Fatty
Acid Conjugates
Thomas Wong, Silpa Narayanan, David P. Brown,* and Zhe-Sheng Chen
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ABSTRACT: A series of 16 conjugates of the tubulin polymerization
inhibitor combretastatin A4 (CA-4) and other functionally related stilbene
with four 18-carbon fatty acids, namely, stearic, oleic, linoleic, and linolenic
acids, have been synthesized in good yields. These new derivatives have been
evaluated against the KB-3-1 (human epidermoid carcinoma), NCI-H460
(human lung cancer), HEK293 (human embryonic kidney), and MCF-7
(human breast adenocarcinoma) cell lines for antiproliferative activity, with
the exhibited cytotoxic activities comparable with those of CA-4 and
colchicine. Compounds 22 and 23, CA-4 conjugates of linoleic and linolenic
acids, respectively, were determined to have exhibited the most active in vitro
assays, with compound 23 exhibiting very similar activity to the parent
compound against the NCI-H460 cell line. Our studies further delineated the
structurally required Z-geometry of the stilbene moiety and that conjugation
of the less active E-stilbenes with the most active fatty acid had minimal or no improvement in their respective activities.
onsidering the persistent global challenge of achieving
Clong-term and permanent treatment solutions for various
forms of cancer, researchers have intensified efforts based on
contemporary approaches such as gene therapy alongside
traditional chemotherapeutic approaches.1−3 Among the small
molecular chemical entities investigated is the stilbene
combretastatin-A4 (CA-4) isolated by the Pettit group from
the South African willow plant Combretum caffrum Kuntze.
Based on chemotherapeutic assays, CA-4 has been demon-
strated to be among the most potent of the isolated classes of
stilbenes. Indeed, the phosphate prodrug 1, having increased
aqueous solubility relative to the parent phenol, has advanced
through phase II clinical trials in treating patients with
advanced recurrent or metastatic anaplastic thyroid cancer
(Figure 1).4−8 Also shown in Figure 1 is the structure of the
tubulin inhibitor colchicine.
conjugated with fatty acids as carriers with the aim of achieving
improved target specificity through increased uptake and
accumulation of the drug in the tumor environment.9
In a previous study, we reported our findings on the
cytotoxicity of substituted benzophenones conjugated with
various fatty acids differing in the degree of unsaturation and
validated increased bioactivity paralleling the degree of
unsaturation.10 The benzophenone scaffolds were examined
considering earlier reports that they interact with microtubules
in a manner similar to CA-4, binding to the colchicine site of β-
tubulin (Figure 2).
With the benefits of fatty acid conjugation established11 and
being cognizant of the dose-limiting cardiotoxic side effects
associated with CA-4 administration, we embarked on the
study of the current series of CA-4-inspired long-chain fatty
acid conjugates anticipating that the incorporated natural fatty
acid carriers might further increase the bioactivity profile of
both stereoisomeric forms of the functionalized stilbenes,
allowing for probable drug administration at reduced
concentrations. A persistent and unavoidable caveat to the
(Z)-stilbenes including CA-4 and its derivatives is the observed
isomerization to the less bioactive (E)-diastereomer. This has
One of the major drawbacks to the use of chemotherapeutic
agents like CA-4 is the systemic toxicity largely resulting from
the lack of target specificity, and this has led to increased
efforts toward refining the strategy of targeted drug delivery. In
one promising approach, various anticancer agents have been
Received: January 8, 2020
Figure 1. Structures of CA-4 phosphate and colchicine.
© XXXX American Chemical Society and
American Society of Pharmacognosy
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Scheme 1. Synthesis of (Z)- and (E)-Stilbene−Fatty Acid
a
Conjugates
Figure 2. Structures of phenstatin and isophenstatin conjugates.
led us to additionally synthesize and probe the preliminary
effects of fatty acid conjugation on these systems. Indeed, the
potential to modify the biological properties of chemo-
therapeutic agents through conjugation with fatty acids has
been harnessed by other investigators. Most recently, Ojike et
al. reported their findings on the antiproliferative activities of
four polyunsaturated fatty acid−CA4 (PUFA−CA4) con-
jugates, attributing the observed cytotoxicity to the inhibition
of microtubule assembly.12 Concurrently and independently,
our team synthesized and characterized the targeted series of
16 fatty acid−stilbene conjugates, which were tested against
four tumor cell lines. Varying degrees of antiproliferative
activities were observed, consistent with previously reported
findings and with the outcomes from the studies performed by
the Lavignac group.12
In another recent study, Callmann et al. reported the
antitumor activity of an 18-carbon α,ω-dicarboxylic acid
conjugate of paclitaxel, which readily forms a noncovalent
complex with human serum albumin (HSA), a well-studied
drug carrier.13 In this alternate pro-drug strategy, the
dicarboxylic acid functions as the binding motif for the drug
carrier, and this mimics the interactions between HSA and
natural long-chain fatty acids. As previously alluded to, we
synthesized strategically and examined both stereoisomeric
forms of the stilbene−fatty acid conjugates to assess the extent
to which the incorporated fatty acid would alter the
cytotoxicity of the stilbenes, and more significantly the impact
on the bioactivity of the otherwise low-activity (E)-stilbenes.
Also surveyed were the incorporation of the more saturated
and more economical fatty acids that are anticipated to be
more amenable to large-scale applications.
a
Reagents and conditions: (a) n-BuLi, THF, 0 °C, 65% combined
yield of 8 and 10, 3.6:1 ratio; 44% combined yield of 9 and 11, 1.6:1
ratio; (b) TBAF, THF, 0 °C, 4 h, 37−91%; (c) RCO2H, DCC,
DMAP,CH2Cl2, MW, rt, 12 min.
were fully characterized with analytical data to completely
authenticate their chemical structures. Product yields varied,
ranging between 25% and 80%. Further attempts at improving
the output of the lower yielding reactions such as extended
reaction times, modifications of the reaction stoichiometry and
physical parameters, and by changing the reaction additives
failed to increase product yields. Depicted in Figures 3 and 4
are the 16 conjugates with respective isolated yields given in
parentheses. Compound 13 was observed to gradually
isomerize into 15; thus mixtures of these stilbenes were
esterified, and the respective conjugates subsequently sepa-
rated.
In vitro antiproliferative studies of all 16 conjugates were
performed by a modified MTT (3-(4,5-dimethylthiazol-2-yl)-
2,5-diphenyltetrazolium bromide) colorimetric assay.17 Cyto-
toxicity studies were performed against the KB-3-1 (human
epidermoid carcinoma), NCI-H460 (human lung cancer),
HEK293 (human embryonic kidney), and the MCF-7 (human
breast adenocarcinoma) cell lines. Also included in Table 1 are
the testing data for the parent stilbenes and the natural product
colchicine as controls. CA-4 and other tubulin-active agents
have been shown to bind to the colchicine site of endothelial
tubulin.18
RESULTS AND DISCUSSION
■
Syntheses of the (Z)- and (E)-stilbenes were accomplished in a
straightforward manner in modest yields by the Wittig
olefination approach as reported in the literature, and as
summarized in Scheme 1, with the photosensitive Z/E product
mixtures being separated by centrifugal chromatography.14
All preliminary steps prior to the olefination reaction were
optimized through the incorporation of microwave irradiation
with yields in excess of 95%. In our hands, formation of the
alkene functionality under microwave irradiation proved
elusive, with the starting materials being largely recovered.15
The silyl deprotection step prior to esterification was also
smoothly accomplished in the microwave synthesizer.
Consistent with previous findings from a group of phenstatin
conjugates, antiproliferative activity was observed to increase
slightly as the tethered fatty acid becomes less saturated.4 As
expected, the derivatized stilbenes generally exhibited reduced
cytotoxicity relative to the parent phenols in these in vitro
assays. These findings also revealed that both the trans stilbene
Conjugation of the stilbenes with the respective fatty acids
was mediated by the coupling agent dicyclohexylcarbodiimide,
DCC, and with 2,6-dimethylaminopyridine, DMAP, as additive
and is also illustrated in Scheme 1.16 The 16 new conjugates
targeted were successfully synthesized by this approach and
B
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Figure 3. Structures and % yields of the stilbene−fatty acid conjugates
20−27.
Figure 4. Structures and % yields of the stilbene−fatty acid conjugates
28−35.
parents and their fatty acid conjugates were generally less
bioactive than their cis counterparts. Indeed, the most active of
the (E) derivatives were compounds 26 and 27. Compound 23
has been shown to be most active overall, and particularly
against the NCI-H460 cell line, with an IC50 value of 0.01 μM.
Against the HEK293 cell line, compound 22 showed the
best activity, with an average IC50 value of 0.02 μM. The IC50
values of compounds 20−23 against the KB-3-1 cells were very
similar, ranging between 0.02 and 0.03 μM. Compound 22 was
determined to be the most active against the HEK293 cell line,
with an IC50 value of 0.02 μM, while compound 20 gave the
best results against the MCF-7 cells (IC50 value of 0.24 μM).
Comparing IC50 values for compounds 26 and 27 against the
KB-3-1 and MCF-7 lines, 4.9 and 2.4 μM respectively, reveals
an approximate 2-fold increase in bioactivity of compound 27
over compound 26. It is also noteworthy that the isomerized
diastereomeric stilbene 35 exhibited significantly reduced
cytotoxicity; at best 200 times weaker than compound 27
against the HEK293 cell line.
In conclusion, we have demonstrated the effects of
incorporating long-chain fatty acids in the structure of a
bioactive natural product and the extent to which biological
properties have been altered. Furthermore, the synthetic utility
of incorporating microwave technology in the seamless
generation of these conjugates under relatively mild conditions
has been established.
EXPERIMENTAL SECTION
■
General Experimental Procedures. All synthetic transforma-
tions were performed in oven-dried glassware. Solutions of air-
sensitive reagents were transferred through a syringe under N2 gas. All
reagents were purchased from Sigma-Aldrich Chemical Co. (St. Louis,
MO, USA). Dichloromethane was distilled over calcium hydride,
while tetrahydrofuran (THF) was distilled over benzophenone and
sodium metal under N2 gas. Microwave-assisted syntheses were
accomplished using a CEM Discover Synthesizer (CEM Corporation,
Matthews, NC, USA.) All TLC plates were visualized under a UV
lamp (254 or 365 nm) or with iodine vapor. Column chromatography
was performed using silica gel as a stationary phase and eluting with
mixtures of hexane and ethyl acetate. Centrifugal chromatography was
performed using a Chromatotron (T-Squared Technology, Inc., San
The associated conjugates 28 through 31 showed activity
that seemed to vary with the cell line investigated. Conjugates
32 through 35 were the least active, generally giving IC50
values greater than 100 μM.
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Table 1. Summary of Cytotoxicity Data of Synthesized Compounds
a
IC50 SD (μM)
b
c
d
e
compound
KB-3-1
NCI-H460
HEK293
MCF-7
2
0.02 0.002
0.01 0.001
0.10 0.015
0.03 0.004
0.03 0.003
0.02 0.002
0.03 0.003
>10
0.06 0.002
0.01 0.001
0.25 0.032
0.03 0.002
0.31 0.045
0.02 0.002
0.01 0.002
>10
0.02 0.002
0.01 0.001
0.20 0.021
0.03 0.004
0.03 0.002
0.02 0.002
0.023 0.003
2.90 0.170
2.60 0.296
2.40 0.212
3.90 0.593
0.06 0.006
0.09 0.019
0.11 0.008
0.24 0.027
>10
>10
>10
>10
>10
12
14
20
21
22
23
24
26
27
28
4.90 0.361
2.40 0.367
3.10 0.297
2.40 0.261
>10
>10
>10
7.70 0.304
a
Concentration inhibiting 50% of cell growth for a 72 h exposure period of test samples. Data represent mean values standard deviation for three
b
c
d
independent experiments. KB-3-1, human epidermoid carcinoma cell line. NCI-H460, human lung cancer cell line. HEK293, human embryonic
kidney cell line. MCF-7, human breast adenocarcinoma cell line.
e
Bruno, CA, USA). Melting points were determined using a Mel-Temp
200W melting point apparatus (Laboratory Devices, Inc.). Infrared
(IR) spectra were obtained on a PerkinElmer Spectrum 2 FT-IR
spectrometer using a PIKE MIRacle ATR (Attenuated Total
Reflectance) accessory. 1H NMR spectra and 13C NMR spectra
were obtained on a Bruker Advance DPX spectrometer at 400 and
100 MHz, respectively. NMR samples were prepared by using ∼0.75
mL of CDCl3 (Cambridge Isotope Laboratories Inc.), and all spectra
were obtained with reference to the solvent peak of CDCl3 at 7.27
triethylamine (0.6 mL, 826 mg, 8.17 mmol) in 6.0 mL of CH2Cl2 was
irradiated at 150 W, 100 psi, at 25 °C for 1 h. The reaction mixture
was subsequently combined with 6 mL of brine and the organic layer
separated. The aqueous layer was further extracted with eight
additional 6 mL portions of CH2Cl2. Drying of the combined organic
layers with anhydrous MgSO4, gravity filtration, and flash chromato-
graphic purification afforded the pure TBS ether (95%).
Formation of stilbenes was accomplished by the established Wittig
protocol. Thus, a 200 mL round-bottomed flask equipped for
magnetic stirring and fitted with a pressure-equalizing dropping funnel
was charged with the phosphonium bromide salt (3.99 g, 7.62 mmol)
in 70 mL of THF. The reaction mixture was cooled to −10 °C, and a
solution of n-BuLi in hexanes (7.2 mL, 1.6 M, 11.4 mmol) added
dropwise via syringe. Following the addition of the base, the mixture
was cooled to −78 °C for 5 min, after which a solution of the silylated
vanillin (1.83 g, 6.86 mmol) in 30 mL of THF was added dropwise
with stirring. After 5 min, the mixture was allowed to warm to 0 °C
and then quenched by pouring into 100 mL of cold brine. The
mixture was next extracted with ethyl acetate (50 mL × 4), and the
combined organic layers were dried over anhydrous MgSO4.
Subsequent filtration and chromatographic purification afforded the
diastereomeric mixture of 9 and 11 (1.31 g, 44%) in a ratio of 1.6:1.
Compound 9: 1H NMR (400 MHz, CDCl3) δ 0.13 (6H, s), 0.98 (9H,
s), 3.61 (3H, s), 3.70 (6H, s), 3.83 (3H, s), 6.43 (1H, d, J = 12.1 Hz),
6.49 (1H, d, J = 12.1 Hz), 6.54 (2H, s), 6.76 (3H, m). Compound 11:
1H NMR (400 MHz, CDCl3) δ 0.17 (6H, s), 1.01 (9H, s), 3.87 (6H,
s), 3.91 (6H, s), 6.72 (2H, s), 6.84 (1H, d, J = 8.1 Hz), 6.89 (1H, d, J
= 16.2 Hz), 6.96 (1H, d, J = 16.1 Hz), 6.98 (1H, dd, J = 2.0, 8.2 Hz),
7.02 (1H, d, J = 1.9 Hz). Physical data and spectroscopic information
for compounds 8 and 10 were consistent with such data that have
been reported in the literature.12
(Z)-2-Methoxy-5-(3,4,5-trimethoxystyryl)phenol (12). In a
round-bottomed flask, compound 8 (2.34 g, 5.43 mmol) was
dissolved in dry THF (25 mL), and TBAF (2.16 g, 8.26 mmol)
was added. Under a positive atmosphere of N2 gas, the mixture was
cooled in an ice−brine bath and stirred for four hours. In a separatory
funnel, cold saturated ammonium chloride (25 mL) was added, and
the reaction mixture was poured in. The aqueous layer was extracted
four times with ethyl acetate. The combined organic layer obtained
was dried with magnesium sulfate and filtered. Flash chromatographic
purification on silica gel (hexane−ethyl acetate, 1:1) afforded
compound 12 (1.24 g, 72%) as a white solid (lit. mp 117−118
°C): 1H NMR (400 MHz, CDCl3) δ 3.70 (6H, s), 3.84 (3H, s), 3.86
(3H, s), 5.54 (1H, s), 6.41 (1H, d, J = 12.2 Hz), 6.47 (1H, d, J = 12.2
Hz), 6.53 (2H, s), 6.73 (1H, d, J = 8.33 Hz), 6.79 (1H, dd, J = 2.0, 8.3
Hz), 6.92 (1H, d, J = 2.0 Hz); 13C NMR (100 MHz, CDCl3) δ 55.9,
56.0, 60.9, 106.0, 110.3, 115.0, 121.1, 129.0, 129.5, 130.6, 132.7,
137.1, 145.2, 145.8, 152.9; anal. calcd for C18H20O5: C 68.35, H 6.37,
found: C 68.10, H 6.83.
1
1
ppm for H NMR spectra and 77.23 ppm for 13C NMR spectra. H
NMR spectra were reported as follows: chemical shift δ (ppm);
singlet (s), doublet (d), triplet (t), quartet/quintet (q), multiplet (m),
coupling constants J = Hz, and integration reported as the number of
protons present. Elemental analyses were performed by Atlantic
Microlab Inc. (Norcross, GA, USA).
Synthesis of Compounds 8−11. A 10 mL reaction vessel was
charged with 3,4,5-trimethoxybenzaldehyde (235 mg, 1.20 mmol) and
sodium borohydride (46.9 mg, 1.24 mmol) in 6.0 mL of absolute
ethanol. The mixture was irradiated at 150 W, 100 psi, at 25 °C with
moderate stirring for 12 min. The reaction mixture was transferred to
a separatory funnel, to which cold brine (6 mL) and ethyl acetate (6
mL) were added, and the organic layer was separated. The aqueous
layer was further extracted with eight additional 6 mL portions of
ethyl acetate, and the organic layers were combined and dried over
anhydrous magnesium sulfate. Subsequent gravity filtration and
evaporation under reduced pressure afforded pure 3,4,5-trimethox-
ybenzyl alcohol (217 mg, 95%).
Three 10 mL reaction vessels were charged with 721 mg (3.64
mmol), 586 mg (2.96 mmol), and 451 mg (2.28 mmol) of 3,4,5-
trimethoxybenzyl alcohol, respectively. To each vessel were added dry
THF (6 mL) and 1 equiv of PBr3. The reaction mixtures were
irradiated at 100 W, 100 psi at 50 °C for 6 min. To the combined
reaction mixtures was added 18 mL of cold saturated sodium
bicarbonate as an extraction solvent. The aqueous layer was further
extracted with six 20 mL portions of diethyl ether. Drying of the
organic layer over magnesium sulfate, followed by filtration and
evaporation under reduced pressure, yielded the pure 3,4,5-
trimethoxybenzyl bromide (2.27 g, 98%).
A mixture of 3,4,5-trimethoxybenzyl bromide (258 mg, 0.988
mmol) and triphenylphosphine (284 mg, 1.08 mmol) in THF (4.0
mL) was microwaved at 150 W, 100 psi at 50 °C for 30 min. After
cooling to room temperature, the mixture was transferred to a round-
bottomed flask, and the solvent evaporated under reduced pressure.
Diethyl ether was added to the residue, which was stored at −20 °C
for 48 h. The ethereal supernatant was subsequently decanted leaving
behind the pure phosphonium bromide salt quantitatively as an off-
white solid.
A mixture of vanillin (or isovanillin, 338.9 mg, 2.23 mmol), DMAP
(278.7 mg, 2.28 mmol), TBSCl (542.1 mg, 3.60 mmol), and
D
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(E)-2-Methoxy-5-(3,4,5-trimethoxystyryl)phenol (14). Com-
pound 14 was prepared according to the method adopted for
compound 12. Thus, ether 10 (2.07 g, 4.81 mmol) reacted with
TBAF (1.92 g, 7.34 mmol) to afford the trans isomer 14 (1.39 g,
91%), isolated as a white solid (lit. mp 103−104 °C): 1H NMR (400
MHz, CDCl3) δ 3.82 (3H, s), 3.86 (3H, s), 3.87 (6H, s), 5.96 (1H, s),
6.69 (2H, s), 6.79 (1H, d, J = 8.4 Hz), 6.85 (1H, d, J = 16.2 Hz), 6.88
(1H, d, J = 16.2 Hz), 6.95 (1H, dd, J = 1.9, 8.3 Hz), 7.14 (1H, d, J =
2.1 Hz); 13C NMR (100 MHz, CDCl3) δ 55.9, 56.1, 60.9, 103.4,
110.8, 111.9, 119.3, 127.0, 127.9, 130.9, 133.4, 137.7, 145.9, 146.6,
153.4; anal. calcd for C18H20O5: C 68.35, H 6.37, found: C 68.53, H
6.47.
1.72 (2H, q, J = 7.3 Hz), 2.05 (4H, m), 2.52 (2H, t, J = 7.5 Hz), 2.78
(2H, t, J = 6.4 Hz), 3.69 (6H, s), 3.77 (3H, s), 3.83 (3H, s), 5.35 (4H,
m), 6.42 (1H, d, J = 12.2 Hz), 6.46 (1H, d, J = 12.2 Hz), 6.50 (2H, s),
6.82 (1H, d, J = 8.5 Hz), 7.00 (1H, d, J = 2.1 Hz), 7.10 (1H, dd, J =
2.1, 8.5 Hz); 13C NMR (100 MHz, CDCl3) δ 14.1, 22.6, 24.7, 25.0,
25.6, 26.4, 27.2, 29.0, 29.1, 29.2, 29.4, 29.6, 30.9, 31.5, 32.7, 33.9,
55.8, 55.9, 60.8, 105.9, 112.0, 123.1, 127.6, 127.9, 128.1, 128.6, 129.5,
130.0, 130.1, 130.2, 132.4, 137.2, 139.6, 150.3, 153.0, 171.6; anal.
calcd for C36H50O6: C 74.71, H 8.71, found: C 73.92, H 8.79.
2-Methoxy-5-((Z)-3,4,5-trimethoxystyryl) phenyl-
(9Z,12Z,15Z)-octadeca-9,12,15-trienoate (23). Compound 23
was prepared according to the procedure described for 20: from
compound 12 (288.7 mg, 0.913 mmol), linolenic acid (251.8 mg,
0.904 mmol), DCC (207.9 mg, 1.01 mmol), and DMAP (114.2 mg,
0.935 mmol), which yielded compound 23 as a clear oil (0.22 g,
42%): IR νmax 2934, 2701, 1635, 1576, 1515, 1450, 1369, 1281, 1154,
1023, 877, 780 cm−1; 1H NMR (400 MHz, CDCl3,) δ 0.97 (3H, t, J =
7.5 Hz), 1.36 (8H, m), 1.72 (2H, m), 2.08 (4H, m), 2.52 (2H, t, J =
7.48 Hz), 2.81 (4H, t, J = 5.99 Hz), 3.70 (6H, s), 3.79 (3H, s), 3.83
(3H, s), 5.36 (6H, m), 6.43 (1H, d, J = 12.2 Hz), 6.47 (1H, d, J = 12.4
Hz), 6.51 (2H, s), 6.84 (1H, d, J = 8.5 Hz), 7.00 (1H, d, J = 2.0 Hz),
7.11 (1H, dd, J = 2.1, 8.5 Hz); 13C NMR (100 MHz, CDCl3) δ 14.3,
20.6, 25.0, 25.5, 25.6, 27.2, 29.0, 29.2, 29.6, 34.0, 55.9, 56.0, 60.9,
105.9, 112.0, 123.2, 127.1, 127.6, 127.8, 128.3, 128.6, 129.5, 130.1,
130.3, 132.0, 132.5, 137.2, 139.6, 150.3, 153.0, 171.7; anal. calcd for
C36H48O6: C 74.97, H 8.39, found: C 73.98, H 8.38.
(E)-2-Methoxy-4-(3,4,5-trimethoxystyryl)phenol (15). Com-
pound 15 was prepared according to the method adopted for
compound 12. Thus, ether 9 (1.96 g, 4.55 mmol) reacted with TBAF
(1.83 g, 7.00 mmol) to afford the trans isomer 15 (0.56 g, 37%),
isolated as a white solid, mp 139−140 °C. The cis isomer 13
completely isomerized to 15, hence was not isolated. IR νmax 3395,
2937, 2833, 1579, 1514, 1466, 1448, 1427, 1338, 1225, 1210, 1167,
1
1119, 1031, 988, 958, 848, 818, 792 cm−1; H NMR (400 MHz,
CDCl3) δ 3.87 (3H, s), 3.92 (6H, s), 3.95 (3H, s), 5.69 (1H, s), 6.72
(2H, s), 6.88 (1H, d, J = 16.4 Hz), 6.90 (1H, d, J = 8.5 Hz), 6.95 (1H,
d, J = 16.2 Hz), 7.01 (1H, d, J = 1.9 Hz), 7.03 (1H, m); 13C NMR
(100 MHz, CDCl3) δ 55.9, 56.1, 61.0, 103.3, 108.2, 114.6, 120.4,
126.5, 128.2, 133.4, 137.6, 145.6, 146.7, 153.4; anal. calcd for
C18H20O5: C 68.34, H 6.37, found: C 68.17, H 6.42.
(E)-2-Methoxy-5-(3,4,5-trimethoxystyryl)phenyl stearate
(24). Compound 24 was prepared according to the procedure
described for 20: from compound 14 (288.7 mg, 0.913 mmol), stearic
acid (177.0 mg, 0.622 mmol), DCC (140.8 mg, 0.683 mmol), and
DMAP (79.5 mg, 0.651 mmol), from which 24 was isolated (0.21 g,
55%) as a white solid (mp 76−77 °C): IR νmax 3021, 2957, 2918,
2851, 1752, 1580, 1513, 1464, 1424, 1253, 1127, 955, 799, 773, 714
(Z)-2-Methoxy-5-(3,4,5-trimethoxystyryl)phenyl stearate
(20). In a reaction tube, a mixture of compound 12 (273.3 mg,
0.864 mmol), stearic acid (247.7 mg, 0.871 mmol), DCC (196.0 mg,
0.950 mmol), and DMAP (106.2 mg, 0.869 mmol) was dissolved in
CH2Cl2 (4 mL). The mixture was irradiated under the following
conditions: 100 W, 25 °C, 100 psi, at 2 min intervals (4 times) for a
total time of 8 min. The reaction mixture was prepurified by flash
chromatography (hexanes−ethyl acetate, 1:1) and then subjected to
centrifugal chromatography (hexane−ethyl acetate, 3:1), which
yielded compound 20 (0.15 g, 29%) as a white solid (mp 61−62
°C): IR νmax 2916, 2852, 1759, 1578, 1506, 1462, 1412, 1130, 1240,
1128, 1028, 851, 797, 713 cm−1; 1H NMR (400 MHz, CDCl3) δ 0.88
(3H, t, J = 6.6 Hz,), 1.35 (28 H, m), 1.72 (2H, q, J = 7.6 Hz), 2.52
(2H, t, J = 7.5), 3.70 (6H, s), 3.78 (3H, s), 3.83 (3H, s), 6.43 (1H, d, J
= 12.2 Hz), 6.46 (1H, d, J = 12.3 Hz), 6.51 (2H, s), 6.84 (1H, d, J =
8.5 Hz), 7.00 (1H, d, J = 2.1 Hz), 7.11 (1H, dd, J = 2.1, 8.5 Hz); 13C
NMR (100 MHz, CDCl3) δ 14.1, 22.7, 25.0, 29.0, 29.3, 29.4, 29.5,
29.6, 29.7, 29.8, 32.0, 34.0, 55.9, 56.0, 60.9, 105.8, 111.9, 123.2, 127.6,
128.6, 128.7, 129.5, 132.5, 137.2, 139.6, 150.3, 153.0, 171.7; anal.
calcd for C36H54O6: C 74.19, H 9.34, found: C, 74.29, H 9.34.
2-Methoxy-5-((Z)-3,4,5-trimethoxystyryl)phenyl oleate (21).
Compound 21 was prepared according to the procedure described for
20: from compound 12 (273.7 mg, 0.865 mmol), oleic acid (246.0
mg, 0.871 mmol), DCC (197.5 mg, 0.957 mmol), and DMAP (106.5
mg, 0.872 mmol), which yielded 21 as a clear oil (0.25 g, 50%): IR
νmax 3003, 2924, 2854, 1763, 1613, 1578.7, 1508, 1455, 1426, 1238,
1127, 1009, 852, 772 cm−1; 1H NMR (400 MHz, CDCl3) δ 0.89 (3H,
t, J = 6.3 Hz), 1.36 (20H, m), 1.72 (2H, q, J = 7.5 Hz), 2.01 (4H, m),
2.52 (2H, t, J = 7.4 Hz), 3.70 (6H, s), 3.79 (3H, s), 3.84 (3H, s), 5.35
(2H, m), 6.43 (1H, d, J = 12.2 Hz), 6.47 (1H, d, J = 12.3 Hz), 6.51
(2H, s), 6.84 (1H, d, J = 8.5 Hz), 7.00 (1H, d, J = 2.1 Hz), 7.11 (1H,
dd, J = 2.1, 8.5 Hz); 13C NMR (100 MHz, CDCl3) δ 14.1, 22.7, 25.0,
27.2, 27.3, 29.0, 29.2, 29.3, 29.5, 29.7, 29.8, 31.9, 34.0, 55.9, 60.9,
105.8, 112.0, 123.2, 128.6, 129.5, 129.8, 130.0, 130.1, 132.5, 137.2,
139.6, 150.3, 153.0, 171.7; anal. calcd for C36H52O6: C 74.45, H 9.02,
found: C 74.17, H 9.23.
1
cm−1; H NMR (400 MHz, CDCl3) δ 0.88 (3H, t, J = 7.0 Hz), 1.41
(28H, m), 1.78 (2H, q, J = 7.6 Hz), 2.59 (2H, t, J = 7.5 Hz), 3.83
(3H, s), 3.86 (3H, s), 3.90 (6H, s), 6.69 (2H, s), 6.87 (1H, d, J = 16.2
Hz), 6.91 (1H, d, J = 7.1 Hz), 6.92 (1H, d, J = 15.7 Hz), 7.22 (1H, d,
J = 2.1 Hz), 7.29 (1H, dd, J = 2.0, 8.5 Hz); 13C NMR (100 MHz,
CDCl3) δ 14.2, 22.7, 25.1, 29.1, 29.3, 29.4, 29.6, 29.7, 31.9, 34.1, 55.9,
56.1, 61.0, 103.4, 112.4, 120.4, 125.2, 127.0, 127.5, 130.6, 133.2,
137.8, 140.1, 150.7, 153.4, 171.9; anal. calcd for C36H54O6, C 74.19, H
9.34;, found: C 74.11, H 9.39.
2-Methoxy-5-((E)-3,4,5-trimethoxystyryl)phenyl oleate (25).
Compound 25 was similarly prepared according to the procedure
described for 20: from compound 14 (215.8 mg, 0.682 mmol), oleic
acid (192.7 mg, 0.682 mmol), DCC (159.6 mg, 0.774 mmol), and
DMAP (87.6 mg, 0.717 mmol), which yielded 25 (0.26 g, 65%) also
isolated as a white solid (mp 38−39 °C): IR νmax 3003, 2921, 2850,
1756, 1584, 1516, 1466, 1428, 1324, 1282, 1247, 1124, 1009, 970,
1
822, 774 cm−1; H NMR (400 MHz, CDCl3) δ 0.88 (3H, t, J = 7.1
Hz), 1.36 (20H, m), 1.78 (2H, m), 2.02 (4H, m), 2.59 (2H, t, J = 7.5
Hz), 3.81 (3H, s), 3.86 (3H, s), 3.88 (6H, s), 5.36 (2H, m), 6.69 (2H,
s), 6.86 (1H, d, J = 16.2 Hz), 6.92 (1H, d, J = 16.1 Hz), 6.92 (1H, d, J
= 8.6 Hz), 7.22 (1H, d, J = 2.1 Hz), 7.26 (1H, dd, J = 2.2, 8.5 Hz);
13C NMR (100 MHz, CDCl3) δ 14.2, 22.7, 25.1, 27.2, 27.3, 29.1, 29.2,
29.3, 29.6, 29.7, 29.8, 31.9, 34.1, 55.9, 56.1, 60.9, 103.4, 112.4, 120.3,
125.2, 127.0, 127.5, 129.7, 130.0, 130.6, 133.2, 137.8, 140.1, 150.7,
153.4, 171.8; anal. calcd for C36H52O6: C 74.45, H 9.02, found: C
74.62, H 9.15.
2-Methoxy-5-((E)-3,4,5-trimethoxystyryl)phenyl-(9Z,12Z)-
octadeca-9,12-dienoate (26). Compound 26 was similarly
prepared according to the procedure described for 20: from
compound 14 (207.9 mg, 0.657 mmol), linoleic acid (199.3 mg,
0.711 mmol), DCC (152.3 mg, 0.738 mmol), and DMAP (81.4 mg,
0.666 mmol), which yielded 26 (0.24 g, 64%) isolated as a white solid
(mp 36−37 °C): IR νmax 3006, 2921, 2851, 1757, 1583, 1509, 1452,
2-Methoxy-5-((Z)-3,4,5-trimethoxystyryl)phenyl (9Z,12Z)-
octadeca-9,12-dienoate (22). Compound 22 was prepared
according to the procedure described for 20: from compound 12
(284.0 mg, 0.898 mmol), linoleic acid (250.2 mg, 0.892 mmol), DCC
(203.1 mg, 0.984 mmol), and DMAP (110.9 mg, 0.908 mmol), which
yielded compound 22 as a clear oil (0.25 g, 49%): IR νmax 2932, 2698,
1
1428, 1322, 1246, 1125, 1005, 975, 825, 772, 716 cm−1; H NMR
(400 MHz, CDCl3) δ 0.89 (3H, t, J = 7.0 Hz), 1.31 (14H, m), 1.78
(2H, q, J = 7.6 Hz), 2.05 (4H, m), 2.60 (2H, t, J = 7.5 Hz), 2.78 (2H,
t, J = 6.4 Hz), 3.84 (3H, s), 3.86 (3H, s), 3.91 (6H, s), 5.35 (4H, m),
1
1635, 1576, 1514, 1449, 1406, 1369, 1154, 1023, 877, 780 cm−1; H
NMR (400 MHz, CDCl3) δ 0.89 (3H, t, J = 6.9 Hz), 1.30 (14H, m),
E
https://dx.doi.org/10.1021/acs.jnatprod.0c00027
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Article
6.70 (2H, s), 6.87 (1H, d, J = 16.2 Hz), 6.93 (1H, d, J = 17.2 Hz),
6.94 (1H, d, J = 8.4 Hz), 7.23 (1H, d, J = 2.1 Hz), 7.30 (1H, dd, J =
2.1, 8.5 Hz); 13C NMR (100 MHz, CDCl3) δ 14.1, 22.6, 25.1, 25.7,
29.1, 29.2, 29.4, 29.6, 31.5, 34.1, 56.0, 56.1, 61.0, 103.4, 112.4, 120.4,
125.2, 127.0, 127.5, 127.9, 128.1, 130.0, 130.25 130.56, 133.12, 137.8,
140.1, 150.7, 153.4, 171.6; anal. calcd for C36H50O6: C 74.71, H 8.71,
found: C 74.93, H 8.86.
J = 7.5 Hz), 2.02 (4H, m), 2.58 (2H, t, J = 7.5 Hz), 3.87 (3H, s), 3.88
(3H, s), 3.92 (6H, s), 5.36 (2H, m), 6.73 (2H, s), 6.97 (2H, s), 7.01
(1H, d, J = 7.9 Hz), 7.07 (2H, d, J = 9.8 Hz); 13C NMR (100 MHz,
CDCl3) δ 14.2, 22.7, 25.1, 27.2, 27.3, 29.1, 29.2, 29.6, 29.7, 29.8, 31.9,
34.1, 55.8, 56.1, 61.0, 103.5, 110.0, 119.1, 123.0, 127.6, 128.8, 129.8,
130.0, 132.9, 136.2, 138.0, 139.4, 151.3, 153.4, 171.9; anal. calcd for
C36H52O6: C 74.45, H 9.02, found: C 74.54, H 9.06.
2-Methoxy-5-((E)-3,4,5-trimethoxystyryl)phenyl-
(9Z,12Z,15Z)-octadeca-9,12,15-trienoate (27). Compound 27
was also prepared according to the procedure described for 20: from a
mixture of compound 14 (251.6 mg, 0.795 mmol), linolenic acid
(237.9 mg, 0.854 mmol), DCC (193.7 mg, 0.939 mmol), and DMAP
(98.2 mg, 0.804 mmol), which yielded 27 (0.23 g, 49%) isolated as a
white solid (mp 41−42 °C): IR νmax 3009, 2929, 2849, 1756, 1583,
1509, 1451, 1428, 1322, 1246, 1124, 1025, 1004, 972, 824, 773, 724
2-Methoxy-4-((Z)-3,4,5-trimethoxystyryl)phenyl-(9Z,12Z)-
octadeca-9,12-dienoate (30). Compound 30 was prepared
according to the procedure described for compound 28 from a
mixture of compounds 13 and 15 (241.1 mg, 0.762 mmol), linoleic
acid (261.8 mg, 0.933 mmol), DCC (177.7 mg, 0.861 mmol), and
DMAP (95.0 mg, 0.777 mmol). This combination yielded 30 (0.28 g,
63%) and 34 (0.11 g, 26%), both isolated as clear, pale yellow oils.
Compound 30: IR νmax 2992, 2916, 2852, 1766, 1582, 1504, 1463,
1416, 1334, 1271, 1246, 1233, 1133, 1034, 1001, 874, 854, 789, 715
1
cm−1; H NMR (400 MHz, CDCl3) δ 0.98 (3H, t, J = 7.5 Hz), 1.41
1
cm−1; H NMR (400 MHz, CDCl3) δ 0.89 (3H, t, J = 7.0 Hz), 1.30
(8H, m), 1.78 (2H, m), 2.08 (4H, m), 2.60(2H, t, J = 7.5 Hz), 2.81
(4H, t, J = 5.8 Hz), 3.84 (3H, s), 3.86 (3H, s), 3.90 (6H, s), 5.36 (6H,
m), 6.70 (2H, s), 6.87 (1H, d, J = 16.2 Hz), 6.93 (1H, d, J = 16.6 Hz),
6.94 (1H, d, J = 8.5 Hz), 7.23 (1H, d, J = 2.1 Hz), 7.30 (1H, dd, J =
2.1, 8.5 Hz); 13C NMR (100 MHz, CDCl3) δ 14.3, 20.6, 25.0, 25.6,
27.2, 29.1, 29.2, 29.6, 34.1, 56.0, 56.1, 61.0, 103.4, 112.4, 120.4, 125.2,
127.0, 127.1, 127.5, 127.8, 128.3, 130.3, 130.6, 132.0, 133.2, 137.8,
140.1, 150.7, 153.4, 171.8; anal. calcd for C36H48O6: C 74.97, H 8.39,
found: C 74.92, H 8.44.
(14H, m), 1.75 (2H, q, J = 7.6 Hz), 2.05 (4H, m), 2.55 (2H, t, J = 7.5
Hz), 2.78 (2H, t, J = 6.2 Hz), 3.63 (3H, s), 3.68 (6H, s), 3.82 (3H, s),
5.36 (4H, m), 6.48 (2H, s), 6.51 (1H, d, J = 12.2 Hz), 6.55 (1H, d, J =
12.1 Hz), 6.86 (2H, m), 6.92 (1H, d, J = 8.6 Hz); 13C NMR (100
MHz, CDCl3) δ 14.1, 22.6, 25.0, 25.6, 26.4, 27.2, 29.0, 29.2, 29.4,
29.6, 30.9, 31.5, 32.7, 34.0, 55.7, 55.9, 60.8, 106.0, 112.8, 121.5, 122.6,
127.9, 128.1, 129.3, 130.0, 130.2, 130.4, 132.3, 136.1, 137.2, 138.9,
150.8, 152.9, 171.8; anal. calcd for C36H50O6: C 74.71, H 8.71, found:
C 74.56, H 8.97.
(Z)-2-Methoxy-4-(3,4,5-trimethoxystyryl)phenyl stearate
(28). In a reaction tube, a mixture of compound 13 and compound
15 (249.5 mg, 0.789 mmol), stearic acid (225.3 mg, 0.792 mmol),
DCC (179.4 mg, 0.870 mmol), and DMAP (96.4 mg, 0.789 mmol)
were dissolved in CH2Cl2 (4 mL). The mixture was irradiated under
the following conditions: 100 W, 25 °C, 100 psi, for 6 min. The
reaction mixture was prepurified by column chromatography
(hexanes−ethyl acetate, 1:1) to isolate the isomeric mixture. The
mixture containing the cis and trans isomers was separated on the
chromatotron (hexane−ethyl acetate, 3:1), which yielded 28 (0.22 g,
48%) as a white solid (mp 63−64 °C) and 32 (0.12 g, 26%) also
isolated as a white solid. Compound 32 was subsequently prepared in
a higher yield as described separately. Compound 28: IR νmax 2916,
2850, 1766, 1656, 1582, 1504, 1463, 1416, 1334, 1271, 1233, 1133,
1034, 1001, 874, 854, 715 cm−1; 1H NMR (400 MHz, CDCl3) δ 0.88
(3H, t, J = 7.0 Hz), 1.38 (28H, m), 1.74 (2H, q, J = 7.6 Hz), 2.56
(2H, t, J = 7.5), 3.64 (3H, s), 3.69 (6H, s), 3.82 (3H, s), 6.48 (2H, s),
6.52 (1H, d, J = 12.2 Hz), 6.56 (1H, d, J = 12.1 Hz), 6.87 (2H, m),
6.92 (1H, d, J = 8.5 Hz); 13C NMR (100 MHz, CDCl3) δ 14.2, 22.7,
25.1, 26.4, 29.1, 29.3, 29.4, 29.5, 29.6, 29.7, 30.9, 31.9, 32.8, 34.1,
55.7, 56.0, 60.9, 106.0, 112.8, 121.5, 122.7, 129.4, 130.4, 132.4, 136.0,
137.2, 138.9, 150.8, 152.9, 171.9; anal. calcd for C36H54O6: C 74.19,
H 9.34, found: C 74.70, H 9.62.
2-Methoxy-4-((E)-3,4,5-trimethoxystyryl)phenyl-(9Z,12Z)-
octadeca-9,12-dienoate (34): IR νmax 2921, 2851, 1767, 1657,
1580, 1507, 1453, 1421, 1127, 1033, 853 cm−1; 1H NMR (400 MHz,
CDCl3) δ 0.89 (3H, t, J = 7.0 Hz), 1.30 (14H, m), 1.77 (2H, q, J = 7.6
Hz), 2.05 (4H, m), 2.59 (2H, t, J = 6.9 Hz), 2.78 (2H, t, J = 6.4 Hz),
3.87 (3H, s), 3.88 (3H, s), 3.92 (6H, s), 5.35 (4H, m), 6.73 (2H, s),
6.97 (2H, s), 7.01 (1H, d, J = 8.0 Hz), 7.07 (2H, d, J = 9.6 Hz); 13C
NMR (100 MHz, CDCl3) δ 14.1, 22.6, 25.1, 25.7, 27.2, 29.1, 29.2,
29.3, 29.6, 31.5, 34.1, 55.9, 56.1, 61.0, 103.5, 110.0, 119.2, 122.0,
127.6, 127.9, 128.1, 128.8, 130.1, 130.3 132.9, 136.1, 138.0, 139.4,
151.3, 153.4, 171.9; anal. calcd for C36H50O6: C 74.71, H 8.71, found:
C 74.00, H 8.67.
2-Methoxy-4-((Z)-3,4,5-trimethoxystyryl)phenyl-
(9Z,12Z,15Z)-octadeca-9,12,15-trienoate (31): Compound 31
was prepared according to the procedure described for compound 28
from a mixture of compounds 13 and 15 (176.4 mg, 0.558 mmol),
linolenic acid (159.6 mg, 0.573 mmol), DCC (126.6 mg, 0.614
mmol), and DMAP (68.3 mg, 0.559 mmol). This combination
yielded 31 (0.17 g, 54%) isolated as a clear oil, and 35 (0.11 g, 35%)
was isolated as a white solid (mp 51−52 °C). Compound 31: IR νmax
2995, 2917, 2852, 1766, 1657, 1583, 1504, 1463, 1417, 1335, 1272,
1
1233, 1133, 1034, 1001, 875, 855, 715 cm−1; H NMR (400 MHz,
2-Methoxy-4-((Z)-3,4,5-trimethoxystyryl)phenyl oleate (29).
Compound 29 was prepared according to the procedure described for
compound 28 from a mixture of compounds 13 and 15 (249.5 mg,
0.789 mmol), oleic acid (225.3 mg, 0.798 mmol), DCC (176.3 mg,
0.855 mmol), and DMAP (95.6 mg, 0.782 mmol). This combination
yielded 29 (0.31 g, 71%) as a pale yellow oil and 33 (0.10 g, 23%)
isolated as a white wax-like solid. Compound 29: IR νmax 2916, 2851,
1766, 1656, 1582, 1504, 1463, 1416, 1335, 1271, 1246, 1233, 1133,
CDCl3) δ 0.97 (3H, t, J = 7.5 Hz), 1.37 (8H, m), 1.75 (2H, q, J = 7.5
Hz), 2.08 (4H, m), 2.55 (2H, t, J = 7.5 Hz), 2.81 (4H, t, J = 6.0 Hz),
3.64 (3H, s), 3.69 (6H, s), 3.82 (3H, s), 5.35 (6H, m), 6.48 (2H, s),
6.51 (1H, d, J = 12.2 Hz), 6.56 (1H, d, J = 12.1 Hz), 6.87 (2H, m),
6.92 (1H, d, J = 8.5 Hz); 13C NMR (100 MHz, CDCl3) δ 14.3, 20.6,
25.0, 25.5, 25.6, 27.2, 29.0, 29.2, 29.2, 29.6, 34.0, 55.7, 55.9, 60.9,
106.0, 112.8, 121.5, 122.7, 127.1, 127.7, 127.8, 128.3, 129.33, 130.3,
130.4, 132.0, 132.3, 137.2, 139.0, 150.8, 152.9, 171.8; anal. calcd for
C36H48O6: C 74.97, H 8.39, found: C 74.05, H 8.35.
1
1034, 1001, 874, 854.3, 715 cm−1; H NMR (400 MHz, CDCl3) δ
0.88 (3H, t, J = 7.0 Hz), 1.34 (20H, m), 1.74 (2H, m), 2.01 (4H, m),
2.56 (2H, t, J = 7.5 Hz), 3.64 (3H, s), 3.69 (6H, s), 3.82 (3H, s), 5.35
(2H, m), 6.48 (2H, s), 6.51 (1H, d, J = 12.2 Hz), 6.56 (1H, d, J = 12.1
Hz), 6.87 (2H, m), 6.92 (1H, d, J = 8.5 Hz); 13C NMR (100 MHz,
CDCl3) δ 14.1, 22.7, 25.0, 27.2, 25.5, 26.4, 27.2, 29.1, 29.2, 29.3, 29.5,
30.9, 31.9, 32.8, 34.0, 55.7, 55.9, 60.9, 106.0, 112.8, 121.5, 122.6,
129.3, 129.7, 130.0, 130.4, 132.3, 136.1, 137.2, 138.9, 150.8, 152.9,
171.8; anal. calcd for C36H52O6: C 74.45, H 9.02, found: C 74.71, H
9.37.
(E)-2-Methoxy-4-(3,4,5-trimethoxystyryl)phenyl stearate
(32). In a reaction tube, compound 15 (122.3 mg, 0.387 mmol),
stearic acid (110.0 mg, 0.387 mmol), DCC (91.1 mg, 0.442 mmol),
and DMAP (48.8 mg, 0.399 mmol) were dissolved in CH2Cl2 (4 mL).
The mixture was irradiated under the following conditions: 100 W, 25
°C, 100 psi, for 6 min. The reaction mixture was prepurified by flash
chromatography (hexanes-ethyl acetate, 1:1), and subsequently by
centrifugal chromatography (hexanes−ethyl acetate, 1:1). The pure
product 32 (0.18 g, 78%) was isolated as a white solid (mp 95−96
°C): IR νmax 3001, 2920, 2850, 1770, 1579, 1509, 1464, 1421, 1338,
2-Methoxy-4-((E)-3,4,5-trimethoxystyryl)phenyl oleate (33).
1
IR νmax 3003, 2919, 2852, 1767, 1580, 1509, 1464, 1422, 1337, 1246,
1243, 1204, 1120, 1035, 1005, 981, 912, 853, 721 cm−1; H NMR
1
1202, 1123, 1035, 1004, 980, 914, 853, 715 cm−1; H NMR (400
(400 MHz, CDCl3) δ 0.88 (3H, t, J = 7.0 Hz), 1.39 (28H, m), 1.76
(2H, q, J = 7.5 Hz), 2.58 (2H, t, J = 7.5 Hz), 3.86 (3H, s), 3.87 (3H,
MHz, CDCl3) δ 0.88 (3H, t, J = 7.1 Hz), 1.36 (20H, m), 1.77 (2H, q,
F
https://dx.doi.org/10.1021/acs.jnatprod.0c00027
J. Nat. Prod. XXXX, XXX, XXX−XXX

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Article
s), 3.90 (6H, s), 6.72 (2H, s), 6.96 (2H, s), 7.00 (1H, d, J = 8.0 Hz),
7.07 (2H, m); 13C NMR (100 MHz, CDCl3) δ 14.2, 22.7, 25.1, 29.1,
29.3, 29.4, 29.6, 29.7, 32.0, 34.1, 55.8, 56.1, 61.0, 103.5, 110.0, 119.1,
123.0, 127.5, 128.8, 132.9, 136.2, 138.0, 139.4, 151.3, 153.4, 171.9;
anal. calcd for C36H54O6: C 74.19, H 9.34, found: C 73.94, H 9.34.
2-Methoxy-4-((E)-3,4,5-trimethoxystyryl)phenyl-
(9Z,12Z,15Z)-octadeca-9,12,15-trienoate (35). Compound 35
was prepared according to the procedure described for 32 from
compound 15 (241.6 mg, 0.764 mmol), linolenic acid (212.6 mg,
0.763 mmol), DCC (173.3 mg, 0.840 mmol), and DMAP (93.3 mg,
0.764 mmol), from which 35 (0.28 g, 63%) was isolated as a white
solid (mp 51−52 °C). Compound 35: IR νmax 3006, 2926, 2851,
1764, 1579, 1509, 1450, 1422, 1328, 1246, 1203, 1117, 1035, 1004,
ACKNOWLEDGMENTS
■
The authors acknowledge the generous financial support of St.
John’s College of Liberal Arts & Sciences and the College of
Pharmacy & Health Sciences of St. John’s University.
REFERENCES
■
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1
980, 911, 852, 830, 717 cm−1; H NMR (400 MHz, CDCl3) δ 0.98
(3H, t, J = 7.5 Hz), 1.40 (8H, m), 1.77 (2H, q, J = 7.6 Hz), 2.08 (4H,
m), 2.58 (2H, t, J = 7.5 Hz), 2.82 (4H, t, J = 5.8 Hz), 3.87 (6H, s),
3.91 (6H, s), 5.36 (6H, m), 6.73 (2H, s), 6.96 (2H, s), 7.00 (1H, d, J
= 8.0 Hz), 7.06 (2H, m); 13C NMR (100 MHz, CDCl3) δ 14.3, 20.6,
25.1, 25.6, 25.7, 27.2, 29.1, 29.2, 29.6, 34.1, 55.8, 56.1, 61.0, 103.6,
110.0, 119.1, 123.0, 127.1, 127.6, 127.8, 128.3, 128.8, 130.3, 132.0,
132.9, 136.2, 138.0, 139.4, 151.3, 153.4, 171.9; anal. calcd for
C36H48O6: C 74.97, H 8.39, found: C 74.87, H 8.42.
Biological Testing. Human epidermoid carcinoma (KB-3-1),
NCI-H460 (human lung cancer cell line), HEK293 (human
embryonic kidney cells), and the MCF-7 (human breast adenocarci-
noma) cell lines were cultured in DMEM medium supplemented with
10% FBS and 1% P/S and maintained in 5% CO2 at 37 °C. The cells
were trypsinized, resuspended, and seeded into a 96-well plate at a
density of ∼5 × 104 cells per well. The cell viability was determined
by MTT assay. Once the cells were attached, different concentrations
of the test drugs were added into each well ranging from 0.1 to 100
μM. Cell viability was measured after 68 h by adding MTT (4 mg/
mL) to the plate. After 4 h of incubation, discarding the supernatant,
100 μL of DMSO was added to all wells. The plates were analyzed
spectrophotometrically at 570 nm. The concentration at which
around 50% of cells survived (IC50) was calculated. IC50 values were
determined using the software GraphPad Prism (version 8).
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ASSOCIATED CONTENT
■
sı
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.jnatprod.0c00027.
Copies of IR, 1H NMR, 13C NMR spectra, and
cytotoxicity data (PDF)
AUTHOR INFORMATION
■
Corresponding Author
David P. Brown − Department of Chemistry, St. John’s
University, Queens, New York 11439, United States;
orcid.org/0000-0002-5601-9603; Phone: +1-718-990-
5219; Email: brownd@stjohns.edu; Fax: +1-718-990-1876
Authors
Thomas Wong − Department of Pharmaceutical Sciences, St.
John’s University, Queens, New York 11439, United States
Silpa Narayanan − Department of Pharmaceutical Sciences, St.
John’s University, Queens, New York 11439, United States
Zhe-Sheng Chen − Department of Pharmaceutical Sciences, St.
John’s University, Queens, New York 11439, United States
(9) (a) Vu, C. B.; Bemis, J. E.; Benson, E.; Bista, P.; Carney, D.;
Fahrner, R.; Lee, D.; Liu, F.; Lonkar, P.; Milne, J. C.; Nichols, A. J.;
Picarella, D.; Shoelson, A.; Smith, J.; Ting, A.; Wensley, A.; Yeager,
M.; Zimmer, M.; Jirousek, M. R. J. Med. Chem. 2016, 59, 1217−1231.
(b) Hackett, M. J.; Zaro, J. L.; Shen, W.-C.; Guley, P. C.; Cho, M. J.
Adv. Drug Delivery Rev. 2013, 65, 1331−1339. (c) Chruma, J. J. D.;
Cullen, D. J.; Bowman, L.; Toy, P. H. Nat. Prod. Rep. 2018, 35, 54.
(d) McEntee, M. F.; Ziegler, C.; Reel, D.; Tomer, K.; Shoieb, A.; Ray,
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.jnatprod.0c00027
Notes
The authors declare no competing financial interest.
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