Hybrid molecule from Farnesylthiosalicylic acid-diamine and phenylpropenoic acid as Ras-related signaling inhibitor with potent antitumor activities

Article abstract of DOI:10.1111/cbdd.12393

Novel series of Farnesylthiosalicylic acid-diamine/phenylpropenoic acid hybrids were designed and synthesized. Their in vitro growth inhibitory assays showed that most compounds displayed strong antiproliferation activity against seven cancer cells. Especially, the new hybrid 12f, by the conjugation of 10a with ferulic acid, could selectively suppress the proliferation of tumor cells and display significantly lower toxicities to normal cells than its intermediate 10a. Furthermore, 12f dose-dependently induced SMMC-7721 cell apoptosis. Additionally, our observations demonstrated that 12f inhibited both Ras-related signaling and phosphorylated NF-κB synergistically, which may be advantageous to the strong antitumor activities of 12f. Our findings suggest that these novel hybrids may hold a great promise as therapeutic agents for the intervention of human cancers.

Full text of DOI:10.1111/cbdd.12393

Chem Biol Drug Des 2015; 85: 145–152
Research Article
Hybrid Molecule from Farnesylthiosalicylic Acid-
diamine and Phenylpropenoic Acid as Ras-related
Signaling Inhibitor with Potent Antitumor Activities
Yong Ling1,2, Zhiqiang Wang1,3, Xuemin Wang1,
ular switches tightly regulating intracellular signal transduc-
tion pathways controlling cell proliferation, differentiation,
and cell apoptosis in normal cells (4–7).
Xianghua Li1, Xinyang Wang1, Wei Zhang1,
Hong Dai1,*, Li Chen2,3,* and Yihua Zhang2
1School of Pharmacy, Nantong University, Nantong
However, active GTP-bound state of Ras proteins are fre-
226001, China
quently found in human malignant tumors due to muta-
tional activation of the Ras oncogene products (H-Ras,
K-Ras, and N-Ras), and the overexpressed Ras-GTP pro-
teins and overstimulated downstream signaling lead to the
development and progression of malignancies (2,8,9).
Therefore, Ras proteins and Ras-related signaling are con-
sidered as promising therapeutic targets in anticancer drug
discovery (10,11). Farnesylthiosalicylic acid (FTS), a potent
competitive Ras inhibitor, detaches the active Ras protein
from the cell membrane, which will thereby block the initia-
tion of downstream signaling events, resulting in the inhibi-
tion of tumor cell uncontrolled proliferation and induction
of cell apoptosis (12,13). FTS has been reported to display
chemopreventive activities in mouse models and clinical
trials (14–17). Yet despite all that FTS displays a limited
therapeutic effect (13, 18). Our previous researches
reported that FTS-diamines significantly improved the anti-
tumor activities compared with FTS, but failed to be selec-
tive to tumor cells (19). On the basic of this, searching for
more potent and safer inhibitors targeting the persistently
active Ras proteins and Ras-related signaling pathway will
be of great significance.
2State Key Laboratory of Natural Medicines, China
Pharmaceutical University, Nanjing 210009, China
3Department of Natural Medicinal Chemistry, China
Pharmaceutical University, Nanjing 210009, China
*Corresponding authors: Li Chen,
chenliduo12@gmail.com; Hong Dai, dh123@ntu.edu.cn
Novel series of Farnesylthiosalicylic acid-diamine/phe-
nylpropenoic acid hybrids were designed and synthe-
sized. Their in vitro growth inhibitory assays showed
that most compounds displayed strong antiprolifera-
tion activity against seven cancer cells. Especially, the
new hybrid 12f, by the conjugation of 10a with ferulic
acid, could selectively suppress the proliferation of
tumor cells and display significantly lower toxicities to
normal cells than its intermediate 10a. Furthermore,
12f dose-dependently induced SMMC-7721 cell apop-
tosis. Additionally, our observations demonstrated that
12f inhibited both Ras-related signaling and phosphor-
ylated NF-jB synergistically, which may be advanta-
geous to the strong antitumor activities of 12f. Our
findings suggest that these novel hybrids may hold a
great promise as therapeutic agents for the interven-
tion of human cancers.
Moreover, natural products play an important role in the
development of anticancer drugs. Hybrids that combined
with parts of natural products are promising potential leads
with advantage to acquire high diversity, inherent biological
activities, and improvement of therapeutic efficacy (20–22).
Ferulic acid and its analog p-hydroxy-phenylpropenoic
acid, two popular natural polyphenol products, widely
occur in the plant kingdom and are associated with the
reduction in the incidence of malignancies, including
breast, colorectal, gastrointestinal, and lung cancer and
display selective antiproliferative activity against some
types of cancer cells (23–27). Furthermore, both of ferulic
acid and p-hydroxycinnamic acid are showed to inhibit the
effect of nuclear transcription factor-jB (NF-jB), which is
independent of Ras signaling and plays a role in cancer
promotion through the competitive inhibition of ATP bind-
ing to IKK-b (28,29). And suppression of NF-jB activity
Key words: antitumor agents, farnesylthiosalicylic acid,
hybrids, NF-jB, phenylpropenoic acid, Ras-related signaling
pathway
Received 17 April 2014, revised 13 June 2014 and accepted
for publication 25 June 2014
Cancer has become the leading cause of morbidity and
mortality worldwide in 2010 (1). Ras proteins are GTPases
as membrane-anchored proteins of all the superfamily
members (2). With cycling between active GTP-bound state
and inactive GDP-bound state associated respectively with
guanine nucleotide exchange factors (GEFs) and GTPase-
activating proteins (GAPs) (3), Ras proteins serve as molec-
ª 2014 John Wiley & Sons A/S. doi: 10.1111/cbdd.12393
145

Ling et al.
leads to inhibition of cellular proliferation and induction of
an apoptotic response (30,31).
mazan crystals were dissolved in 150 lL DMSO, and
absorbance was measured spectrophotometrically at
570 nm using an ELISA plate reader. The inhibition
induced by each tested compound at the indicated con-
centrations was expressed as a percentage. The concen-
tration required for 50% inhibition (IC50) was calculated
using the software (GraphPadPrism, GraphPad Software
Version 4.03, Inc., La Jolla, CA, USA).
Notably, several researches reported that inhibiting Ras-
related signaling pathway associated with NF-jB could
lead to synergistically promoting the tumor cell apoptosis
and inhibiting cell proliferation (32–34). In view of the
above description, we hypothesized that the novel types of
hybrids through conjugating FTS-diamine with phenylprop-
enoic acids could efficiently block the Ras-related signal-
ing, selectively inhibit tumor cell proliferation and induce
tumor cell apoptosis with a synergy for treatment of can-
cer. Therefore, twenty FTS-diamine/phenylpropenoic acid
hybrids were designed and synthesized, and their in vitro
antitumor activities, apoptotic effects, and inhibitory effect
of Ras-related signaling and NF-jB were evaluated.
Herein, the synthesis and biological evaluation of these
compounds were reported.
Flow cytometry assay of cell apoptosis
SMMC-7721 cells were cultured overnight and incubated
in triplicate with the tested compound (3.0, 6.0, and
12 lM) or vehicle for 48 h. The cells were harvested and
stained with FITC-Annexin V and PI (BioVision, Inc., San
Francisco, CA, USA) at room temperature for 15 min. The
percentage of apoptotic cells was determined by flow
cytometry (Beckman Coulter, Fullerton, CA, USA) analysis.
Materials and Methods
Western blot assay
The mechanisms of the cell apoptosis and the inhibitory
activity of Ras-related signaling and NF-jB were deter-
mined by Western blot assay. SMMC-7721 cells at
1.5 9 105/mL were treated with 3.0, 6.0, or 12 lM 12f or
vehicle control for 8 h. After harvested and lysed, the cell
lysates (50 lg/lane) were separated by SDS-PAGE (12%
gel) and transferred onto nitrocellulose membranes. After
blocked with 5% fat-free milk, the target proteins were
probed with antiphospho-Akt (Ser473), antiphospho-ERK
(Thr202/Tyr204), antiphospho-Raf (Ser259), anti-Akt, anti-
phospho-NF-jB p65, anti-NF-jB, and anti-b-actin anti-
bodies (Cell Signaling, Boston, MA, USA), respectively.
The bound antibodies were detected by HRP-conjugated
second antibodies and visualized using the enhanced
chemiluminescent reagent. The relative levels of each sig-
naling event to control b-actin were determined by densi-
metric scanning.
Infrared (IR) spectra (KBr) were recorded on a Nicolet
Impact 410 instrument (KBr pellet). 1H NMR spectra were
recorded with a Bruker Avance 300 MHz spectrometer at
300 K, using TMS as an internal standard, and the 1H
NMR spectra for part of the synthetic compounds can be
found in the Appendix S1. MS spectra were recorded on
a Mariner Mass Spectrum (ESI). Element analysis was per-
formed on an Eager 300 instrument. All compounds were
routinely checked by TLC and 1H NMR. TLCs and pre-
parative thin-layer chromatography were performed on
silica gel GF/UV 254, and the chromatograms were con-
ducted on silica gel (200–300 mesh; Merck, Merck & Co.,
Inc., Darmstadt, Germany). All solvents were reagent
grade and, when necessary, were purified and dried by
standards methods. Organic solutions were dried over
anhydrous sodium sulfate.
Compounds 2 and 4 were commercially available. Com-
pounds 3 and 5 were synthesized following the synthetic
protocols we reported previously (19). Methods of synthe-
sis and analytical data of the target compounds are pre-
sented in the Appendix S1.
Results and Discussion
Chemistry
The synthesis of these hybrids 11a-j and 12a-j were
described in Scheme 1. The parent compound FTS was
obtained from thiosalicylic acid 2. Firstly, compound 2 was
protected by methyl esterification with methanol and
SOCl2 to afford compound 3. Next, (E,E)-farnesol 4 was
treated with PBr3 to give (E,E)-bromo-farnesyl 5, which
was then reacted with compound 3 to obtain methyl (E,E)-
farnesylthiosalicylicate 6. Then, the intermediate 6 was
hydrolyzed with NaOH solution to gain FTS 1. In addition,
diamines 7a-e was N-monoprotected with (Boc)2O to gen-
erate 8a-e, which were later reacted with FTS to give
compounds 9a-e in the presence of ethyl chloroformate
and N-methylmorpholine. Compounds 9a-e were depro-
tected by treating with trifluoroacetic acid (TFA) to gain
10a-e, which were subsequently treated with p-acetoxy-
MTT assay
Human gastric cancer cells (SGC7901), human hepatocel-
lular carcinoma cells (SMMC-7721), human bladder carci-
noma cells (EJ), human ovarian cancer cells (SKOV-3),
murine hepatocarcinoma cell (H22), human lung cancer
cells (H460), human pancreatic carcinoma cells (Panc-1)
at 104 cells per well were cultured in 10% FBS DMEM in
96-well flat-bottom microplates overnight. The cells were
incubated in triplicate with, or without, different concentra-
tions of each tested compound for 48 h. During the last
4 h incubation, 30 lL of tetrazolium dye (MTT) solution
(5 mg/mL) was added to each well. The resulting MTT-for-
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Ras-related Signaling Inhibitor
Scheme 1: Synthetic pathway for the
preparation of farnesylthiosalicylic acid-
diamine/phenylpropenoic acid hybrids.
Reaction conditions and reagents: (a)
SOCl2, MeOH, 0 °C-reflux, 8 h, 85%; (b)
PBr3, pyridine, n-hexane, ether, 0 °C-r.t.,
4 h, 76%; (c) K2CO3, CH3CN, 50 °C, 6 h;
(d) 1 N NaOH, MeOH, 60 °C, 10 h, 82%;
(e) (Boc)2O, CH2Cl2, 0 °C, 2 h, r.t.,
overnight, 72–86%; (f) i) 1, N-
methylmorpholine, ethyl chloroformate, THF,
0 °C, 1 h; ii) Et3N, THF, 0 °C, 1 h, 75–82%;
(g) TFA/CH2Cl2 (v/v = 1:1), r.t., overnight,
88–94%; (h) p-acetoxy-phenylpropenoic
acid chloride, Et3N, THF, 0 °C, 1 h, 75–
86%; (i) NaOH, MeOH, r.t., 2 h, 90–96%.
phenylpropenoic acid chloride prepared from their respec-
tive acids with SOCl2 to yield target compounds 11a-j.
And 11a-j was then hydrolyzed to gain the other series of
target compounds 12a-j. The target products were purified
by column chromatography, and their structures were
SKOV-3 (human ovarian cancer cells) were evaluated in
vitro by MTT assay with FTS and sorafenib as positive
controls. The three tested cell lines were incubated with
each of the target compound at a concentration of
25 lM, and their tumor inhibiting rates were described in
Figure 1. Most compounds exhibited strong growth inhib-
itory activities with the maximum inhibiting rate of 99%,
which was higher than that of FTS with near 40% on
each cell line. Especially, significant antiproliferative effects
of 11a, 11f-g, 12a-b, and 12f-h could be observed to
possess comparably with or more potent than that of
sorafenib, and these compounds were selected for fur-
ther and broader investigation of the inhibitory activity
against human tumor cells.
1
characterized by IR, H NMR, MS, and elemental analyses
(see Appendix S1).
Biological evaluation
To preliminarily screen out active molecules, the antiprolif-
eration activities of target compounds 11a-j and 12a-j
against Panc-1 (human pancreatic carcinoma cells),
SMMC-7721 (human hepatocellular carcinoma cells) and
Figure 1: Inhibition of cell proliferation (%) of
target compounds in Panc-1, SMMC-7721, and
SKOV-3 cell lines after incubation for 48 h at a
concentration of 25 lM. Data are expressed as
means Æ SD of each compound from three
separate measurements.
Chem Biol Drug Des 2015; 85: 145–152
147

Ling et al.
Table 1: The IC50 values of 11a, 11j, 11g, 12a, 12b, and 12f-h against seven cancer cell lines
In vitro inhibition of cancer cells proliferation (IC50a, lM)
Compound
SGC-7901
SMMC-7721
EJ
SKOV-3
H22
H460
Panc-1
FTS
Sorafenib
11a
41.3 Æ 5.56
11.5 Æ 2.71
15.7 Æ 1.34
10.7 Æ 1.23
17.7 Æ 2.10
13.8 Æ 1.81
14.0 Æ 1.62
8.11 Æ 0.90
10.1 Æ 1.13
13.1 Æ 1.23
69.7 Æ 3.85
18.7 Æ 2.65
12.2 Æ 1.56
11.8 Æ 1.26
15.5 Æ 1.39
8.93 Æ 0.96
13.9 Æ 0.91
5.22 Æ 0.79
5.89 Æ 0.72
9.82 Æ 1.08
47.6 Æ 3.28
22.9 Æ 3.53
13.9 Æ 1.72
11.9 Æ 1.10
18.6 Æ 1.46
10.4 Æ 1.18
17.7 Æ 1.85
5.94 Æ 1.03
7.44 Æ 1.22
11.7 Æ 1.37
51.2 Æ 5.06
9.25 Æ 2.15
17.9 Æ 1.65
9.84 Æ 1.31
15.0 Æ 1.89
7.93 Æ 1.12
20.6 Æ 2.51
6.53 Æ 0.64
7.65 Æ 1.01
13.6 Æ 1.20
56.3 Æ 4.28
13.8 Æ 1.43
15.2 Æ 1.36
8.93 Æ 1.03
14.9 Æ 1.60
9.83 Æ 1.16
19.3 Æ 1.77
6.09 Æ 0.58
6.58 Æ 0.87
12.8 Æ 1.04
49.2 Æ 4.47
10.8 Æ 2.36
12.6 Æ 1.39
10.4 Æ 1.18
13.6 Æ 1.52
10.1 Æ 0.87
15.6 Æ 2.04
7.87 Æ 0.90
8.29 Æ 1.01
10.5 Æ 1.07
53.6 Æ 5.77
12.3 Æ 1.46
14.0 Æ 1.31
10.3 Æ 1.26
12.5 Æ 1.33
6.85 Æ 1.17
14.3 Æ 1.10
5.57 Æ 0.72
7.42 Æ 0.89
9.06 Æ 1.18
11f
11g
12a
12b
12f
12g
12h
aThe antiproliferation activities of individual compounds against each of the cancer cell lines were determined by the MTT assay and
expressed as the IC50 (a dose achieved 50% inhibition in the growth of cancer cells cultured). Data are expressed as mean Æ SD from
three independent experiments.
A
B
Figure 2: (A) Inhibitory effects of 12f on the proliferation of SMMC-7721 and LO2 cells. SMMC-7721 and LO2 cells were incubated with
the indicated concentrations of 12f for 48 h. Cell proliferation was assessed using the MTT assay. Data are means Æ SD of the inhibition
(%) from three independent experiments. (B) Inhibitory activity of 10a, 12f, and farnesylthiosalicylic acid against SMMC-7721 cells. SMMC-
7721 cells were incubated with the indicated compounds at 10 lM for 48 h, and cell proliferation was assessed by the MTT assay. Data
are means Æ SD of the inhibition (%) from three independent experiments. *p < 0.01 versus control of SMMC-7721, #p < 0.01 versus
control of LO2.
Next, MTT assay employing SGC7901 (human gastric can-
cer cells), SMMC-7721 (human hepatocellular carcinoma
cells), EJ (human bladder carcinoma cells), H22 (murine
hepatocarcinoma cell), SKOV-3 (human ovarian cancer
cells), H460 (human lung cancer cells), and Panc-1
(human pancreatic carcinoma cells) incubated with 11a,
11f-g, 12a-b, and 12f-h was carried out using FTS and
sorafenib, a well-known Ras-related signal inhibitor, as
positive controls. The values of half-inhibitory concentration
(IC50) about selected active compounds were measured
and presented in Table 1. The results indicated that each
of them displayed clearly increased antitumor activities
with IC50 values in a low micromolar range compared with
FTS and even had a comparable to or lower IC50 values
than sorafenib did. Notably, 12f showed the strongest
antitumor activities with IC50 value range of 5.22–8.11 lM,
which were 5–13-fold less than those of FTS (IC50 = 41.3–
69.7 lM). Inspired by the prominent antitumor activities of
12f in vitro, an insight into whether 12f possessed strong
cytotoxicity to normal cell would be required.
Given the strong growth inhibitory activity of 12f in vitro,
the selectivity profile was investigated by examining the
inhibitory effects of 12f on the growth of SMMC-7721
cells and LO2 cells (human hepatocellular normal cells),
which were dosed with 12f at increasing concentrations.
A dose-response curve was presented in Figure 2A. As a
result, no apparent growth inhibitory activity was
observed on LO2 cells; however, 12f displayed obvious
antiproliferation activity on SMMC-7721 cells in a dose-
dependent manner in vitro, which demonstrated that 12f
could selectively suppress the proliferation of tumor cells.
As compound 10a was the intermediate of 12f
(Scheme 1), the inhibitory activity of 12f, FTS, and 10a at
a concentration of 10 lM or the vehicle control against
SMMC-7721 cells and LO2 cells were also evaluated for
48 h. Figure 2B showed that treatment with FTS could
cause a nearly decreased proliferation function of both
SMMC-7721 and LO2 cells, which were similar to those
of the cells treated with vehicle. Furthermore, treatment
with 10a retained a certain degree of inhibitory potency
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Ras-related Signaling Inhibitor
A
B
Figure 3: Compound 12f induced SMMC-7721
cell apoptosis in vitro. SMMC-7721 cells were
incubated with the indicated concentrations of
12f and 12 lM farnesylthiosalicylic acid for 48 h,
and the cells were stained with FITC-Annexin V
and PI, followed by flow cytometry analysis. (A)
Flow cytometry analysis. (B) Quantitative analysis
of apoptotic cells. Data are expressed as
means Æ SD of the percentages of apoptotic
cells from three independent experiments.
*p < 0.01 versus control.
but was significantly less potent than 12f against SMMC-
7721 cells and had no selectivity to tumor cells. More
noteworthy aspect, the new hybrid 12f, after the conju-
gation of 10a with ferulic acid, not only had higher inhibi-
tory effects on the tumor cell proliferation, but also
significantly reduced molecule toxicity compared with
10a, which had high toxicities to normal cells. These
observations indicated that 12f was believed to be a
safer and more potent antitumor agent, which may be
worthy of further research.
the dose of 12f gradually increased, apoptotic SMMC-
7721 cells exhibited an accumulation that were 53.65%
for 6.0 lM and 85.75% for 12 lM, which were in sharp
contrast to those induced by FTS at high concentration
(only 19.36% for 12 lM). The data demonstrated that 12f
could result in an occurrence of SMMC-7721 cell apopto-
sis in a dose-dependent manner and have an enhance-
ment of apoptosis inducing effect in SMMC-7721 cells
compared with FTS.
To get insight into the mechanisms underlying the anti-
cancer activity of these FTS-diamine/phenyl-propenoic
acid hybrids, we examined the inhibitory effects of the
active compound 12f on the expression of Ras-related
pathway and NF-jB proteins. The levels of phospho-
Raf, phospho-ERK, phospho-Akt, Akt, as well as phos-
phor-NF-jB, NF-jB were determined in SMMC-7721
cells by immunoblotting assays, and using b-actin as
the control. As shown in Figure 4, the levels of phos-
pho-Raf, phospho-ERK1/2, phospho-Akt were obviously
To determine whether the hybrids’ antiproliferation activi-
ties were attributed to their pro-apoptotic role in tumor
cells, the apoptosis rates of SMMC-7721 cells incubated
with different concentrations of 12f (3, 6, or 12 lM), FTS
(12 lM), or vehicle alone were determined by FITC-Annexin
V/PI staining and flow cytometry. As described in Figure 3,
treatment with 12f at 3.0 lM showed an apoptosis effect
on SMMC-7721 cells that induced 20.80% of cell apopto-
sis compared with the control (5.42%). Furthermore, with
Chem Biol Drug Des 2015; 85: 145–152
149

Ling et al.
A
B
Figure 4: Immunoblot analysis of the expression and phosphorylation of the Ras-related signal events in vitro. (A) SMMC-7721 cells were
treated with vehicle (control), different doses of 12f, or farnesylthiosalicylic acid were homogenized, and their lysates were subjected to
immunoblot analysis using antiphospho-Raf (Ser259), antiphospho-ERK1/2 (Thr202/Tyr204), anti-Akt, antiphospho-Akt (Ser473),
antiphoshpo-NF-jB p65, anti-NF-jB, and anti-b-actin antibodies, respectively. b-Actin was used as the control. (B) Quantitative analysis.
The relative levels of each signaling event to control b-actin were determined by densimetric scanning. The data are expressed as means
Æ SEM of three duplicate experiments. *p < 0.01 versus control.
reduced under the treatment of 12f (3.0, 6.0, or 12
lM), whereas no significant change in the expression of
Akt was found, indicating that our designed hybrid could
inhibit the Ras downstream signaling in a dose-depen-
dent manner which might attribute to the impact of the
FTS fragment in 12f. Moreover, the suppression effect
of 12f (dose of 12 lM) on Ras-related signaling was
more remarkable than that of FTS at the same concen-
tration. On the other hand, it is necessary and interest-
ing to probe further into the level of phosphor-NF-jB
expression, and the result highlighted a concentration-
dependent inhibition of the phosphor-NF-jB. In contrast,
there was no phosphor-NF-jB inhibiting effect of FTS at
the same dose (12 lM). These results gave an evidence
at the molecular levels that 12f could not only block
Ras-related signaling, but also have an inhibition on
phosphorylated NF-jB simultaneously, which may syner-
gistically contribute to the enhanced activities of 12f in
the tumor growth inhibition and induction of cell apopto-
sis.
acid, hybrid molecules not only exerted more sensitive to
tumor cells than FTS-diamines, but also evidently
reduced normal cell toxicities. Moreover, FTS/hydroxylcin-
namic acid hybrids, compounds with relatively shorter
diamine linker displayed more potent, for instance, 12f
exhibited optimal antitumor activities. However, the pre-
cise mechanisms underlying the SAR of these hybrids
remain further investigation.
Conclusions
Summarily, a series of FTS/hydroxylcinnamic acid hybrids
was designed and synthesized and their in vitro antitumor
activities were evaluated. Most of them displayed strong
antiproliferation activities against seven cancer cells in vitro.
Especially, novel hybrid 12f, with the strongest in vitro anti-
tumor activities (IC50 = 5.22–8.11 lM), exerted selectively
grow inhibitory activity against tumor cells, greatly improv-
ing the sensitive to tumor cells compared with FTS and
10a in vitro. Moreover, 12f could dose-dependently induce
cancer cell apoptosis superior to FTS. Interestingly, 12f
exhibited a simultaneous inhibition to Ras-related signaling
and phosphorylated NF-jB, which may synergistically con-
tribute to the significant antitumor activities and apoptosis
inducing effects.
Structure–activity relationships analysis
Structure–activity relationships (SARs) revealed that an
improvement of antitumor activities was observed for
FTS-diamine/phenylpropenoic acid hybrids compared with
FTS. Among these hybrids, FTS-diamine/ferulic acid
hybrids showed a relatively stronger growth inhibitory
activity against tumor cells than FTS-diamine/p-hydroxy-
cinnamic acid hybrids did, such as 11f-j, 12f-j versus
11a-e, 12a-e, indicating that ferulic acid fragment exhib-
ited more helpful effect than p-hydroxy-cinnamic acid did
on enhancing antitumor activities. Furthermore, after the
removal of acetyl group on 11a-j, the expose of phenolic
hydroxyl group on 12a-j led to a significant potentiation
of antitumor activities. One plausible explanation may be
that 12a-j with more hydrogen bonds would be more
active to bind the galectin site of farnesyl-Ras. In addi-
tion, with an introduction of hydroxylphenylpropenoic
Acknowledgments
We gratefully acknowledge the financial support by the
Natural Science Foundation of China (Grant No. 8130
2628) and Jiangsu Province (Grant No. BK2011389),
China Pharmaceutical University for the Open Project Pro-
gram of State Key Laboratory of Natural Medicines
(SKLNMKF201415), Applied Research Projects of Nantong
City (BK2012085), and also thank a project funded by the
Priority Academic Programs Development of Jiangsu
Higher Education Institutions (PAPD).
150
Chem Biol Drug Des 2015; 85: 145–152

Ras-related Signaling Inhibitor
farnesylthiosalicylic acid (salirasib) in patients with solid
tumors. Cancer Chemother Pharmacol;65:235–241.
16. Schneider-Merck T., Borbath I., Charette N., De Sae-
Conflict of Interests
All authors declare no conflict of interests.
€
ger C., Abarca J., Leclercq I., Horsmans Y., Starkel P.
(2009) The Ras inhibitor farnesylthiosalicyclic acid (FTS)
prevents nodule formation and development of preneo-
plastic foci of altered hepatocytes in rats. Eur J Can-
cer;45:2050–2060.
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Additional Supporting Information may be found in the
online version of this article:
Appendix S1. Synthesis and analytical data of the target
compounds.
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