Novel hybrid molecules of 3,5-bis(benzylidene)-4-piperidones and dichloroacetic acid which demonstrate potent tumour-selective cytotoxicity

Article abstract of DOI:10.1016/j.bmcl.2019.126878

A novel class of hybrid molecules 2a-o was designed as candidate antineoplastic agents from dichloroacetic acid which is a known inhibitor of pyruvate dehydrogenase kinase and a number of cytotoxic 3,5-bis(benzylidene)-4-piperidones 1. In general these new hybrid molecules are potent cytotoxins towards human HCT116 colon cancer cells. A number of lead molecules emerged having the IC₅₀ values in the double digit nanomolar range. Most of these compounds are less toxic to human CRL1790 non-malignant colon cells and hence the selectivity index (SI) figures for most of the compounds are huge; in the case of 2c-g, m, n, the SI values are in excess of 100. Compounds 2g, 2j, 2m and 2n displayed >100-fold higher potency than the reference drug 5-FU. Quantitative structure-activity relationships revealed that the potencies of the compounds in series 2 increase as the magnitude of the Hammett σ and Taft σ* values rise. X-ray crystallographic of a representative compound 2c revealed various structural features which may influence cytotoxic potencies. Several representative compounds lowered the mitochondrial membrane potential and increased the production of reactive oxygen species in HCT116 cells. A minimal effect was noted in altering the percentage of cells in different phases of the cell cycle. Some future directions have been outlined for analog development.

Full text of DOI:10.1016/j.bmcl.2019.126878

Journal Pre-proofs
Novel hybrid molecules of 3,5-bis(benzylidene)-4-piperidones and dichloro-
acetic acid which demonstrate potent tumour-selective cytotoxicity
Mohammad Hossain, Swagatika Das, Umashankar Das, Alireza Doroudi,
Jianfeng Zhu, Jonathan R. Dimmock
PII:
S0960-894X(19)30856-X
https://doi.org/10.1016/j.bmcl.2019.126878
BMCL 126878
DOI:
Reference:
Bioorganic & Medicinal Chemistry Letters
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28 October 2019
28 November 2019
Please cite this article as: Hossain, M., Das, S., Das, U., Doroudi, A., Zhu, J., Dimmock, J.R., Novel hybrid molecules
of 3,5-bis(benzylidene)-4-piperidones and dichloroacetic acid which demonstrate potent tumour-selective
cytotoxicity, Bioorganic & Medicinal Chemistry Letters (2019), doi: https://doi.org/10.1016/j.bmcl.2019.126878
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Novel hybrid molecules of 3,5-bis(benzylidene)-4-piperidones and
dichloroacetic acid which demonstrate potent tumour-selective
cytotoxicity
Mohammad Hossaina, Swagatika Dasb, Umashankar Dasb,*, Alireza Doroudib,c, Jianfeng Zhud,
Jonathan R. Dimmockb,*
aSchool of Sciences, Indiana University Kokomo, Kokomo, Indiana 46904, USA
bDrug Discovery and Development Research Cluster, University of Saskatchewan, Saskatoon,
Saskatchewan S7N 5E5, Canada
cDepartment, School of Pharmacy, Ahvaz Jundishapur University of Medical Sciences, Ahvaz,
Iran, 6135733184
dSaskatchewan Structural Sciences Centre, University of Saskatchewan, Saskatoon, Saskatchewan S7N
5C9, Canada
-----------------------------------------------
* Corresponding authors
E-mail addresses: umashankar.das@usask.ca (U. Das) and jr.dimmock@usask.ca (J. R.
Dimmock)

ABSTRACT
A novel class of hybrid molecules 2a-o was designed as candidate antineoplastic agents from
dichloroacetic acid which is a known inhibitor of pyruvate dehydrogenase kinase and a number
of cytotoxic 3,5-bis(benzylidene)-4-piperidones 1. In general these new hybrid molecules are
potent cytotoxins towards human HCT116 colon cancer cells. A number of lead molecules were
emerged having the IC50 values in the double digit nanomolar range. Most of these compounds
are less toxic to human CRL1790 non-malignant colon cells and hence the selectivity index (SI)
figures for most of the compounds are huge; in the case of 2c-g, m, n, the SI values are in excess
of 100. Compounds 2g, 2j, 2m and 2n displayed more than 100-fold higher potency than the
reference drug 5-FU. Quantitative structure-activity relationships revealed that the potencies of
the compounds in series 2 increase as the magnitude of the Hammett σ and Taft σ* values rise.
X-ray crystallographic of a representative compound 2c revealed various structural features
which may influence cytotoxic potencies. Several representative compounds lowered the
mitochondrial membrane potential and increased the production of reactive oxygen species in
HCT116 cells. A minimal effect was noted in altering the percentage of cells in different phases
of the cell cycle. Some future directions have been outlined for analog development.
Keywords : cytotoxicity / 3,5-bis(benzylidene)-4-piperidones / tumour-selective toxicity / cell
cycle analysis / mitochondrial membrane potential / X-ray crystallography / dichloroacetyl /
QSAR

Cancer is a devastating disease globally. The primary interest of this laboratory is the
discovery of novel cytotoxins which display high potency and have greater toxicity towards
neoplasms than non-malignant cells. We have demonstrated previously that many 3,5-
bis(benzylidene)-4-piperidones 1 possess promising cytotoxic potencies.1-3 These compounds are
believed to react readily with thiols but not amino or hydroxyl groups.4-6 Thus these molecules
should not interact with nucleic acids and the problem of causing genotoxicity may therefore be
absent in these compounds. In addition, these molecules permit sequential interactions with
cellular constituents whereby reactions occur at one of the olefinic carbon atoms which is
followed by further thiol alkylation at the remaining olefinic carbon atom. This sequence of
reactions may lead to compounds which display greater toxicity to tumours than normal cells
since previous studies revealed that after an initial chemical insult, certain tumours become more
susceptible to cytotoxins than non-malignant cells.7,8 These interesting structural features
associated with 1 has created our further interest to design novel molecules based on 3,5-
bis(benzylidene)-4-piperidone as the core cytotoxic warhead to enhance tumour-selective
cytotoxicity.
A number of tumours have undergone metabolic reprogramming using glycolysis to produce
energy instead of oxidative phosphorylation. This phenomenon is known as the Warburg effect.
Pyruvate dehydrogenase kinase 1 (PDK1) is required for glycolysis and inhibiting this enzyme
will therefore reverse the Warburg effect. Dichloroacetic acid (DCA) is an inhibitor of PDK19
that has been evaluated as an anticancer agent.10 However, there are problems associated with the
clinical use of DCA such as its low potency. Thus the objective of the present study was to attach
the dichloroacetyl group to the cytotoxic warhead 1 to create novel hybrid molecules as potent
cytotoxic agents. In addition, depending on the lability of the bond between DCA and the
cytotoxins, release of DCA may take place and since DCA has demonstrated chemosensitizing
properties,11 the potency of the cytotoxin may be enhanced.
In this study, novel hydride molecules in series 2 have been disclosed as potent cytotoxic
agents. The aryl substituents in 2 were mainly chosen on the basis of their varied electronic,
hydrophobic and steric properties. For example, substituents are found in all four quadrants of a
Craig diagram for para substituents in regard to their electronic and hydrophobic properties.12 In
addition, two related compounds were prepared namely 3 and 4 in order to develop structure-
activity relationships vide infra. Since colon cancer is one of our main research interests, the
compounds were evaluated against human HCT116 colon cancer cells which were used
previously in our studies with conjugated unsaturated ketones.1,13,14 In order to assess tumour-
selective cytotoxicity, these molecules were screened against non-malignant human CRL1790
colon epithelial cells.
[PLEASE INSERT SCHEME 1]
The synthesis of the compounds in series 1-4 has been portrayed in Schemes 1 and 2. In
brief, the compounds in series 2 were prepared as follows. Acid catalyzed condensation between
various aryl aldehydes and 4-piperidone led to the formation of 1a-o which were further reacted
with dichloroacetyl chloride to produce compounds in series 2 (Scheme 1). The synthesis of 3
was obtained by N-acetylation of 1a while compound 4 was prepared from 1l (Scheme 2).
Details of the syntheses are given in the supplemental section.
[PLEASE INSERT SCHEME 2]

The evaluation of 1a, 2a-o, 3 and 4 as well as two reference compounds namely sodium
dichloroacetate and 5-fluorouracil (5-FU) towards HCT116 and CRL1790 cells are portrayed in
Table 1.
[PLEASE INSERT TABLE 1]
The evaluation of series 2 against HCT116 cells reveals that with the exception of 2l, o, all of
the analogs in series 2 have submicromolar IC50 values, i.e., in 87 % of the compounds. The most
potent molecules with IC50 values in the 30-60 nanomolar range are 2d, e, g, j, m, n and are
clearly lead molecules. On the other hand, the IC50 values of 2l, o are in the low micromolar
range. Both of these compounds have electron releasing groups in the aryl rings, i.e., the σp
values of the 4-hydroxy and 4-dimethylamino groups are -0.37 and –0.83, respectively.15 This
effect will increase the electron densities on the olefinic carbon atoms thereby retarding
nucleophilic attack by cellular thiols. Methylation of the hydroxyl groups led to 2h with an IC50
value which is 14 times lower than 2l.
The question arises as to whether one or more physicochemical properties of the aryl
substituents influence cytotoxic potencies. The sigma (σ) and sigma star (σ*) constants are a
measure of the electronic properties of the aryl substituents while the pi (π) and molar
refractivity (MR) figures reflect the hydrophobic and steric properties of the groups in the aryl
rings, respectively. Hence linear and semilogarithmic plots between each of these parameters and
the IC50 values towards HCT116 and CRL1790 cells were made. For HCT116 cells, negative
correlations were noted between the σ/σ* constants and the IC50 values of 2a-o from the linear
(p<0.01) and semilogarithmic (p<0.01) plots. When the outlier 2l was omitted, a negative
correlation was found between the IC50 figures of 2a-k, m-o and the σ/σ* constants from the
linear (p<0.05) and the semilogarithmic (p<0.01) plots. The outlier 2o was then removed from
the analysis. A negative correlation between the IC50 values of 2a-n and the σ/σ* constants were
observed from the semilogarithmic plot (p<0.05). No other correlations were noted. These data
reveal that potency increases as the magnitude of the σ/σ* constants rise. Hence in the future
compounds with strongly electron attracting groups should be placed in the aryl rings. Linear and
semilogarithmic plots between the IC50 values of 2a-o, 2a-k,m-o and 2a-n towards CRL1790
cells and the σ/σ*, π and MR constants of the aryl substituents were made. Only a trend to a
correlation between the σ/σ*values and the IC50 figures of 2a-n in the linear and semilogarithmic
plots were noted (p<0.1).
A comparison of the cytotoxic potencies of 1a, 2a and 3 were made with a view to finding if
the presence of a dichloroacetyl group contributes significantly to potency. The IC50 figures of
1a, 2a and 3 are 3.50, 0.23 and 0.28 µM, respectively, which indicates that while N-acylation of
1a leads to potency increases, the introduction of two chloro atoms into 3 creating 2a does not
lower the IC50 figures.
Compound 4 has a N-acyl group on the piperidyl nitrogen atom and dichloroacetyloxy
substituent on both aryl rings. This compound has the same potency towards HCT116 cells as 2a
and 3 suggesting that the common structure of 2a, 3 and 4 namely the 3,5-bis(benzylidene)-1-
carbonyl-4-oxo-piperidinyl group affects cytotoxic potencies considerably.
The biodata generated for 1a, 2a-o, 3 and 4 were compared with the potency of 5-FU which
is a drug used in treating colon cancer. With the exception of 2l, o, all of the compounds are
more potent than 5-FU, e.g., 2g, j, 2m, n are >100 times more potent than 5-FU towards

HCT116 cells. As indicated in Table 1, a second reference compound namely sodium
dichloroacetate displays weak potency towards HCT116 cells.
The next consideration was to determine whether 1a, 2a-o, 3 and 4 are less toxic to human
CRL1790 non-malignant colon cells. These results are presented in Table 1. Except for 2o, the
IC50 values are greater towards CRL1790 cells than HCT116 cells indicating that these
compounds display greater toxicity to the tumour cell line. In order to determine the
magnitude of the differential in toxicity towards the cell lines, selectivity index (SI) values were
computed. These figures are the quotients of the IC50 values of the compounds towards
CRL1790 and HCT116 cell lines. These SI values are presented in Table 1. The majority of the
SI values are huge. The greatest selective toxicity was noted with the following compounds (SI
values in parentheses) namely 2m (540), 2j (378), 2n (378) and 2g (305). Virtually all of the
compounds have SI values greater than 5-FU while sodium dichloroacetate has the same toxicity
to HCT116 and CRL1790 cells.
[PLEASE INSERT FIGURE 1]
X-ray crystallographic structure of a representative compound 2c was determined with a
view to finding some of its molecular features which may contribute to its cytotoxic potency.
The ORTEP diagram of 2c is presented in Figure 1. An interesting feature of the X-ray
crystallographic structure of this compound is that it is disordered. The fluoro atom is attached to
the C9 carbon atom in 81 % of the unit cells while in 19% of the cases, the fluoro atom is bonded
to the C11 atom. Cellular thiols are predicted to undergo nucleophilic attack at carbon atoms C6
and C13. Hence the stereochemistry at this portion of the molecule may affect the rate and extent
of thiol alkylation. This molecule adopts the E configuration at the two olefinic double bonds.An
evaluation was made to determine whether the two aryl rings are coplanar with the adjacent
olefinic groups. The C2-C13-C14-C15 and C2-C13-C14-C19 torsion angles are 148.85 and -
32.14, respectively. The C4-C6-C7-C8 and C4-C6-C7-C12 angles are -157.63 and 25.41,
respectively. Hence the aryl rings do not lie in the same plane as the olefinic groups and the two
rings are orientated in different directions. This lack of coplanarity may be due to non-bonded
interactions between the C1He and C19H atoms as well as the C5He and C12H atoms. The
interatomic distances are 2.318 Ǻ and 2.206 Ǻ, respectively, indicating that non-bonded
interactions occurred.These observations may contribute to the relative potencies of 2c towards
HCT116 and CRL1790 cells which give rise to the huge SI value of 135. In other words, the
stereochemistry of 2c (and analogs) may be such as to render the compound highly toxic to the
neoplasm but much less so to non-malignant cells. The ORTEP diagram suggests that the C5He
and Cl1 atoms are in close proximity but the interatomic distance is 2.817 Ǻ revealing the
absence of non-bonded interactions. On the other hand, the C5He and C12H atoms are 2.206 Ǻ
apart suggesting some non-bonded interaction may be taking place. In addition, the conformation
of the central piperidine ring may affect the alignment of the molecule at binding sites and in the
case of 2c it is in the half chair conformation.
The next stage of the investigation was to attempt to find some of the ways in which
representative compounds exert their toxicity to HCT 116 cells. Four compounds were chosen
for these evaluations namely 2a, o, n and 3 which differ in their potencies (2n>2a, 3>2o) and
tumour-selective cytotoxicity (2n>3>2a>2o). Three mode of action studies were undertaken in
HCT116 cells by examining whether these compounds lower the mitochondrial membrane

potential (MMP), increase the production of reactive oxygen species (ROS) and have any effect
on the cell cycle.
[FIGURE 2]
ATP production is controlled by the mitochondria. In many tumours, the MMP is higher than
is found in non-malignant cells.16 Hence the disruption of the MMP in neoplasms may lead to
a reduction in cell growth or apoptosis. Concentrations of the IC50 and twice the IC50 values of
2a, n, o and 3 towards HCT 116 cells were used and the results are portrayed in Figure 2. The
data indicate that in the case of 2a, n and 3 as well as 5-FU, cytotoxicity is caused, at least in
part, by a lowering of the MMP. On the other hand, the toxic effects of 2o are not likely due to
any effect on the MMP.
[FIGURE 3]
Cancer cells show redox imbalance due to increased ROS level compared to normal cells.
This unique feature of cancer cells is exploited for targeted cancer therapy. In order to assess the
effect of these novel cytotoxins on ROS generation, compounds 2a, n, o and 3 were evaluated in
HCT 116 cells. The results reveal that these compounds and 5-FU increase the concentration of
ROS which likely contributes to their toxicity. These results are portrayed in Figure 3.
[TABLE 2]
A number of anticancer drugs act at different stages of the cell cycle. Hence 2a, n, o, 3 were
examined for this effect in HCT116 cells. The results are presented in Table 2. In general the
biodata indicate that these compounds have little or no effect on different stages of the cell cycle.
There is a slight elevation in the percentage of cells undergoing apoptosis and in general a
lowering of cells in the G0-G1 phase.
A question arises as to whether a rupture of the amidic bond occurs during the bioevaluation
of the compounds in series 2. Hence 2a was incubated at 37˚C in a mixture of dimethylsulfoxide
and 0.1 M phosphate buffer.17 The mixture was extracted with chloroform after 0, 24 and 48
1
hours and the product was examined by H NMR spectroscopy. The three spectra are identical
indicating that under these conditions 2a was stable at 37˚C for 48 hours (the temperature and
time of the cytotoxic bioassays). Hence the bioactivity displayed by 2a, and probably the related
compounds 2b-o are likely due to the intact molecules and not to any breakdown products.
Finally investigation was to assess druglikeness properties of 2a-o as per the guidelines
suggested by Lipinski et al.18 and Muegge et al.19 using a free web tool, SwissADME.20 The
physicochemical data reveal that all the compounds except 2g comply to the criteria for druglike
properties (data not shown), thereby confirming that compounds in series 2 are excellent
cytotoxins that warrant further preclinical evaluations as candidate antineoplstic agents.
In conclusion, a novel series of antineoplastic agents have been disclosed which display far
greater toxicity to human colon cancer HCT116 cell line than to a non-malignant one. A number
of lead compounds emerged from this study. In particular, 2g, 2j, 2m and 2n are promising
cytotoxins having IC50 values in very low micromolar range (0.03-0.04 µM) and very high
tumour selective cytotoxicity (SI>300-fold). These compounds displayed >100-fold higher
cytotoxic potencies than the reference drug 5-FU. Among these four molecules, 2j, 2m and 2n

satisfy druglike properties favourably. The mode of action studies reveal that the potencies of
the cytotoxins in series 2 includes the lowering of the MMP and the generation of ROS. In the
future these lead molecules will be evaluated against a wide range of tumours and non-malignant
cells to determine which types of malignancies are the most sensitive to these dichloroamides
and also further in vivo evaluations will be pursued to find the most promising preclinical
candidates for treating colon cancers. Further analog development needs to be pursued
vigorously with the aim to find compounds with IC50 figures in single digit nanomolar range.
Acknowledgements
The authors thank the Office of the Executive Vice Chancellor for Academic Affairs, Indiana
University and the Maunders McNeil Foundation Inc. for financial support for this study.
Conflict of interest
The authors have no competing financial interests to declare.
Supplementary section
Details of the synthesis of the compounds in series 1-4, quantitative structure-activity
relationship determinations, the bioassays and X-ray crystallography are presented on pages S1
to S10 in the supplementary section.
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Table 1. Evaluation of 1a, 2a-o, 3 and 4 against HCT116 and CRL1790 cells
Compound
Aryl
Substituent
H
H
2-F
3-F
4-F
3,4-F2
4-Cl
3,4-Cl2
4-OCH3
3,4-(OCH3)2
3,4,5-(OCH3)3
3,4-OCH2O
4-OH
4-CH3
4-NO2
4-N(CH3)2
H
IC50(µM)a
CRL1790
SIb
HCT 116
1a
2a
2b
2c
2d
2e
2f
2g
2h
2i
2j
2k
2l
3.50±0.13
0.23±0.054
0.21±0.059
0.11±0.033
0.05±0.020
0.06±0.023
0.13±0.014
0.04±0.005
0.27±0.033
0.11±0.033
0.04±0.10
0.32±0.042
3.85±0.14
0.03±0.005
0.03±0.006
13.30±2.73
0.28±0.072
0.23±0.067
14.8±3.81
4.02±0.883
9.45±0.29
12.5±0.50
11.0±0.86
14.8±0.81
14.6±0.67
11.1±0.64
14.9±0.89
12.2±0.56
13.2±0.81
10.6±0.94
15.1±0.56
21.1±0.98
13.8±0.61
16.2±0.61
11.1±0.76
9.12±0.62
20.8±0.82
16.4±0.20
12.5±0.94
18.7±0.82
2.70
54.4
52.4
135
292
185
115
305
48.9
96.4
378
65.9
3.58
540
370
0.69
74.3
71.3
0.85
4.65
2m
2n
2o
3
4
OCOCHCl2
- - -
- - -
SDAc
5-FUd
aThe IC50 value is the concentration of the compound required to inhibit the growth of the cells
by 50%.
bThe letters SI refer to the selectivity index which is the quotient of the IC50 values of the
compounds towards CRL1790 and HCT 116 cells.
cSDA means sodium dichloroacetate.
d5-FU refers to 5-fluorouracil.

Table 2. Effect of 2a, n, o, 3 on the cell cycle of HCT116 cells.
Compounda
Phases of cell cycleb
Apoptosis
3.6**
3.6*
G0-G1
44.7*
44.4**
42.9**
45.5
S
G2-M
29.6
27.8
29.9
30.0
29.4
Ploids
1.8***
2.2
2a
2n
2o
19.9
21.4*
20.8*
18.3
18.4
4.6**
3.5*
1.4**
2.4
3
DMSO
2.4
46.8
2.5
aThe concentrations of 2a, n,o,3 used are 0.23, 0.03, 10.96 and 0.28 µM respectively.
bThe figures are the percentage of the cells in various phases of the cell cycle. Differences
between the phases of the cell cycle compared to dimethylsulfoxide are represented as *(p<0.05),
** (p<0.01) and *** (p<0.001).

Captions for Schemes and Figures
Scheme 1. The synthetic chemical route to the compounds in series 2. The reagents used are as
follows namely i = 10% aqNaOH/ethanol for 1a-k, m, o; CH3COOH/HCl for 1l, n; ii =
Cl2CHCOCl/N(C2H5)3/HCl /1,2–dichloroethane, CHCl3. The substituents in the aryl rings in
series 2 are represented in table 1.
Scheme 2. The synthetic chemical route to the compounds in series 3 and 4. The reagents used
are as follows: i=10%aqNaOH; ii=CH3COCl/N(CH3)3; iii=CH3COOH/HCl; iv=
(CH3)3COCOCl/tetrahydrofuran, v = Cl2CHCOCl/N(C2H5)3, tetrahydropyran.
Figure 1. The ORTEP diagram of 2c.
Figure 2. The effect of 2a, n, o, 3 on the mitochondrial membrane potential potential of HCT116
cells.
Figure 3. The effect of 2a, n, o, 3 on the production of reactive oxygen species in HCT116 cells.

R1
R1
O
CHO
R3
O
R2
R3
R2
R3
R1
R2
R5
R4
i
+
R5
R5
N
H
N
H
R4
R4
1a-o
R1
R1
O
N
R2
R3
R2
R3
R5
Cl
R5
R4
R4
O
Cl
2a-o
Scheme 1

O
O
N
ii
N
H
H
O
i
O
1a
H
3
N
H
iii
O
O
N
O
iv
v
O
O
Cl
Cl
OH
HO
N
H
HO
OH
O
O
N
Cl
Cl
CH3
CH3
CH3
CH3
O
O
1l
H3C
H3C
4
Scheme-2
13

Figure 1
14

20000
15000
10000
5000
0
)
)
)
)
)
)
)
)
)
)
)
O
M
M
M
M
M
M
M
M
M
M
M
S
µ
µ
µ
µ
µ
µ
µ
µ
µ
µ
µ
M
F
3
6
8
6
4
3
6
6
2
0
0
(
2
4
0
0
9
9
2
5
1
1
D
.
.
.
.
.
.
.
.
(
(
U
0
0
0
0
0
1
0
0
(
P
P
(
(
(
(
(
1
2
a
a
(
(
3
3
C
N
n
n
5
2
2
2
2
o
o
C
D
2
2
4
C
,
2
Figure 2
30000
20000
10000
0
)
)
)
)
)
)
)
)
)
)
O
M
M
M
M
M
M
M
M
M
M
S
µ
µ
µ
µ
µ
µ
µ
µ
µ
µ
M
3
6
8
6
0
4
3
6
6
2
(
2
4
0
0
9
9
2
5
.
1
(
D
.
.
.
.
.
.
.
U
0
0
0
0
0
1
0
0
(
O 2
H 2
F
(
(
(
(
(
1
2
5
a
a
(
(
3
3
n
n
2
2
2
2
o
o
2
2
Figure 3
GRAPHICAL ABSTRACT
15

O
O
N
Cl
O
Cl
R
R
R
R
Cl
N
H
Cl
O
1a o
2a o
-
-
Cl
IC50 (HCT116) IC50(CRL1790) SI*
2m
(R= 4-CH3) 0.03 0.005
5-FU 4.02 ± 0.883
16.2±0.61
18.7±0.82
540
4.65
*SI: IC50 (CRL1790)/IC50 (HCT116)
Highlights
- Novel hybrid molecules displaying high potency towards human colon cancer HCT116 cells.
- Most compounds are far less toxic to non-malignant CRL1790 cells leading to high selectivity
index values.
- Lead molecules demonstrated >100 times higher potency than a reference drug 5-FU.
- The mode of action of representative compounds includes lowering of the mitochondrial
membrane potential and increase in ROS generation.
Declaration of interest statement
The authors have no competing academic and financial interests to declare.
16