Synthesis, crystal structure, and anticancer properties of cyclic monocarbonyl analogs of curcumin

Article abstract of DOI:10.1007/s00044-009-9284-7

A series of novel indan-2-one and dibenzylidenepiperidin-4-one compounds were synthesized and screened for anticancer activities. The compounds are symmetrical and they have conjugated double bonds. They closely resemble the curcumin analogs which are fou

Full text of DOI:10.1007/s00044-009-9284-7

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2011) 20:81–87
DOI 10.1007/s00044-009-9284-7
ORIGINAL RESEARCH
Synthesis, crystal structure, and anticancer properties of cyclic
monocarbonyl analogs of curcumin
•
Natesan Sundarmurthy Karthikeyan
•
Kulathu Iyer Sathiyanarayanan Paduthapillai Gopal Aravindan
•
P. Giridharan
Received: 12 May 2009 / Accepted: 4 December 2009 / Published online: 25 December 2009
Ó Springer Science+Business Media, LLC 2010
Abstract A series of novel indan-2-one and dibenzyli-
denepiperidin-4-one compounds were synthesized and
screened for anticancer activities. The compounds are
symmetrical and they have conjugated double bonds. They
closely resemble the curcumin analogs which are found to
possess anticancer properties. The structure of the com-
pounds was confirmed by single crystal study and wherever
the compound is a powder, the structures were confirmed
by spectral data (IR, NMR, and Mass).
2004; Aggarwal et al., 2003; Zeng et al., 2009). In the last
few years, a number of natural and synthetic compounds
have proven to inhibit HIV-1 IN in in vitro assays, but have
failed to provide antiviral efficacy in HIV-1 infected cells.
Curcumin derivatives are integrase inhibitors in vitro
endowed with antiviral activity in cell-based assays (Santo
et al., 2005). Curcumin is capable of inducing apoptosis
in various cancer cell lines (Karunagaran et al., 2005;
Lakshmi et al., 2008) and can suppress cancer formation
(Li et al., 2002). Both phase I and II clinical trials show
that curcumin is well tolerated and is effective for cancer
patients, (Dhillon et al., 2006) suggesting curcumin as a
potential drug in cancer prevention and therapy (Dube
et al., 2008; Chandru et al., 2008). Further, it also enhances
wound healing (Panchatcharam et al., 2006). Curcumin is
nontoxic even at high dosage. It has been classified as
‘‘generally recognized as safe’’ (GRAS) by the National
Cancer Institute (Osawa et al., 1995).
Keywords 2-Indanone ꢀ 1-Benzyl-4-piperidone ꢀ
Aromatic aldehyde ꢀ Curcumin derivatives ꢀ
Molecular docking
Introduction
Curcumin, a compound isolated form turmeric—the
‘‘Golden spice,’’ possesses many biological properties. It is
a traditional medicine for liver diseases, indigestion,
rheumatic arthritis, and insect bite in India. Owing to its
anticancer and antiangiogenic properties, low molecular
weight and lack of toxicity, curcumin could be an ideal
candidate for a chemotherapeutic agent (Adams et al.,
The Curcumin analogs (1,5-diaryl-3-oxo-1,4-pentadie-
nyl group) have been mounted on a variety of cyclic
scaffolds leading to the discovery of a number of potent
cytotoxins (Pati et al., 2009; Fadda et al., 2009). This group
is considered to react at a primary binding site (Fig. 1a).
However, the magnitude of the bioactivity observed will be
influenced by the presence of other structural units in the
molecule, which align at an auxiliary site (Fig. 1b).
Several studies have revealed that compounds in which
R is an acyl group possess increased cytotoxic potencies
compared to the analogs when R is a hydrogen atom (Das
et al., 2007). Thus, by expanding the size of the molecules,
there is a possibility of additional binding of the ligand at a
receptor which results in the lowering of the IC50 values
(Pati et al., 2009). In curcumin analogs, the substitution
pattern of the aromatic moiety is of importance. The most
active compounds have a fluorine atom or a methoxyl
N. S. Karthikeyan ꢀ K. I. Sathiyanarayanan (&)
Chemistry Division, School of Advanced Sciences, VIT
University, Vellore 632 014, India
e-mail: sathiya_kuna@hotmail.com
P. G. Aravindan
Physics Division, School of Advanced Sciences, VIT University,
Vellore 632 014, India
P. Giridharan
Piramal Life Sciences Ltd., Mumbai 400 063, India
123

82
Med Chem Res (2011) 20:81–87
A mixture of cyclic ketone (0.01 mol) and the appropriate
aldehyde (0.02 mol) in alcoholic ammonium acetate
(15 ml, 0.01 mol) was gently heated and left overnight at
room temperature. The separated solid was purified by
column chromatography.
a
A primary binding site.
O
5
1
3
4
2
Biology
A possible auxiliary binding site
O
The two series (IND—Fig. 2 and BP—Fig. 3) of eight
monocarbonyl curcumin analogs were synthesized and
screened for anticancer activity. Recently, antibacterial
activities of monocarbonyl analogs of curcumin have also
been discussed (Liang et al., 2008b). To the best of our
knowledge, this is the first time an investigation has been
made for the anticancer activity of IND series (Fig. 2).
The anticancer screening was performed using cell lines,
HCT-116 (Colon cancer), Panc-1 (Pancreatic cancer),
H460 (Non small lung cancer), Calu-1 (Lung cancer),
ACHN (Renal cancer). The results compare well with
W138 (Normal lung fibroblast cells).
b
N
R
The protion of the molecule which is capable of enhacing or
reducing cytotoxic potencies
Fig. 1 a Primary binding sites. b A possible auxiliary binding site
group in the ortho position of the OH-group of the
p-hydroxyphenyl moiety (Gafner et al., 2004). Ortho-
substituents consistently exhibit better activity than their
meta- and para-counterparts (Adams et al., 2004).
O
CHO
O
AcONH4
+
EtOH
R
R
R
Cyclic Ketone
Curcumine analogue
Aromatic aldehyde
Experimental
R = H, 4-Cl, 4-CH3, 4-OCH2CH3, 4-OCH2CH=CH2, 3-OH, 2-CH3
Scheme 1 General synthesis of curcumin analogs (1–8)
Chemistry
The synthesis and biological evaluation of curcumin ana-
logs have been reported previously. In this study, the
authors wish to report a new synthetic method (Scheme 1),
using ammonium acetate, for monocarbonyl curcumin
analogs (symmetrical aromatic moieties) with more stable
chemical structures, as well as their anticancer screening in
various cell lines.
O
R
R
R
1
This procedure is more convenient than the literature
method (Adams et al., 2004; Pati et al., 2008, 2009; Liang
et al., 2008a), easy to synthesis, isolate, and less expensive.
R
1
Fig. 2 Compound 1–3
Fig. 3 Compound 4–8
O
N
R
R
1. (PCIND);R = H, R1 = Cl
2. (PMIND);R = H, R1 = OCH3
3. (OMIND);R = OCH3, R1 = H
4. (BP);R = H, R1 = H
R
R
1
1
5. (PMBP);R = H, R1 = OCH3
6. (PEBP);R = H, R1 = OCH2CH3
7. (PABP);R=H,R1 =OCH2CH=CH2
8. (MHBP); R = OH, R1 = H
123

Med Chem Res (2011) 20:81–87
83
Chart 1 Cell mortality for
OMIND, BP, and PMBP in
various cell lines at different
concentration (lM)
Chart 2 Cell mortality for
PEBP and MHBP in various cell
lines at different concentration
(lM)
Biology
Results and discussion
The CCK-8 nonradioactive colorimetric assay was carried
out (Jing-yan et al., 2006; Cell Counting Kit-8 technical
manual) to characterize the in vitro growth of human tumor
cell lines as well as to test the cytotoxic activity of these
compounds. The compound PEBP showed the highest
anticancer activity among the compounds tested, and it
showed IC50 of 8.3 lM in Colon cancer, 7.2 lM in Pan-
creatic cancer, 5.5 lM for Non small lung cancer, 8.1 lM
for Lung cancer, and 6.9 lM for Renal cancer cells
(Chart 2). The activity was tested in the concentration
ranges of 0.01–30 lM. The activity was found to increase
with increase in concentration. Fortunately, none of the
compounds is found to be toxic in normal primary lung
Chemistry
The structures of curcumin analogs (1–8) were in accor-
dance with their crystal data and spectroscopic data. The
FT-IR spectrum of the compounds in general exhibited the
absorption band at around 1705–1569 cm-1 indicating the
carbonyl group and olefinic bonds of a,a0-(EE)-bis(substi-
tuted benzylidene)cycloalkanones are in conjugation. The
mass spectrum of the compounds showed its respective
1
peaks. In the H-NMR spectrum of the compounds, the
vinylic protons either occur as singlet at around d
7.61–7.49 ppm or as merged ones with the multiplet of
aromatic protons ranging from d 8.25 to 6.96 ppm.
123

84
Med Chem Res (2011) 20:81–87
Fig. 4 a ORTEP diagram of
BP. b Docking of receptor
model—1m3g with BP
fibroblast cells. If we see the order of activity, the order is
roughly as follows OMIND \ PMBP \ BP \ MHBP \
PEBP (Charts 1, 2). Out of the two series, BP derivatives
(Fig. 3) are more active than IND series (Fig. 2). This may
be due to the reason that the auxiliary binding site in BP is
capable of enhancing the activity. However, in the case of
IND series, the auxiliary binding site is not that capable of
increasing the activity. This is clear from the Fig. 1a and b.
This gets support from the earlier observation in which
some BP compounds were reported for selective toxicity
for malignant cells (Pati et al., 2008). However, the activity
of BP series is moderately affected by the substitution
present in it. Within the BP series, the highest activity is
shown by PEBP followed by MHBP, BP, and PMBP
(Charts 1, 2). This order may be due to the reason that, out
of ethoxy and methoxy, ethoxy is more active than the
methoxy due to the large chain of ethyl group. The mod-
erately good activity of MHBP is due to the reason that OH
derivatives normally increase the anticancer activity.
In the case of Colon cancer, the order follows
OMIND \ MHBP \ BP \ PEBP \ PMBP. Here, again
the ethyl group in the substitution plays a major role. With
Pancreatic cancer, the order follows OMIND \ MHBP \
PMBP \ BP \ PEBP. Here also the ethyl substitution is
responsible for the highest activity. However, in the case of
Non small lung cancer, the order of the activity is changed
completely, and here, the most active one is OMIND and the
least active is PEBP. The order follows PEBP \ PMBP \
BP \ MHBP \ OMIND. Here, the activity of all the com-
pounds increases tremendously, when compared to other
cancers. In the case of Lung cancer, again the order of
activity resembles the order followed in Colon cancer
PMBP \ OMIND \ MHBP & BP \ PEBP. The activity
here is not as pronounced as in the case of Non small lung
cancer. In the case of Renal cancer, the activity follows the
order PMBP \ OMIND \ MHBP \ BP \ PEBP.
From the above observations, the PEBP (Chart 2) is
found to be more active than all other compounds.
Molecular modeling
Before the compounds were tested in in vitro, molecular
modeling studies were performed. Docking studies were
undertaken by means of the patch dock program (Patch-
Dock Server 2008), with the aim of better understanding
the binding mode of the curcumin analogs to the biological
target. We got crystalline structure for only two com-
pounds, namely, BP (Fig. 4a) and PMBP (Fig. 5a), and
these two were subjected to docking studies.
123

Med Chem Res (2011) 20:81–87
85
Fig. 5 a ORTEP diagram of
PM. b Docking of receptor
model—1m3g with PMBP
Tyrosine phosphorylation of proteins is required for
signal transduction in cells and for growth regulation. A
mitogen-induced gene (PAC-1) has been cloned from
human T cells and encodes a 32-kDa protein that contains a
sequence that defines the enzymatic site of known protein
phosphotyrosine phosphatases (PTPases). We subjected
these two compounds for molecular modeling studies
against catalytic domain of MAPK protein phosphatase
(PAC-1) (residue 170–314) (Wu et al., 2007; RCSB Pro-
tein Data Bank—Receptor 1m3g).
structural modifications of curcumin have an important
potential for drug development.
Spectral data
1,3-Bis(4-chlorobenzylidene)-indan-2-one (PCIND)
Yellow amorphous powder; mp 182°C; 83% Yield; IR
1
(KBr) cm-1 2918, 1713, 1623, 776; H-NMR (DMSO-d6,
400 MHz): d 7.27–7.74 (14H, olefinic protons and ArH);
GC–MS: m/z = 376 (M - 1)?.
Initial data reveal that the compound binds to PAC-1 and
modulates its expression (Figs. 4b, 5b). The PAC-1 is a
direct target of E2F-1, which plays a main role in cell cycle
regulation. The enhanced activity of this compound in cancer
cells may be due to PAC-1 modulation in cancer cells.
1,3-Bis(4-methoxybenzylidene)-indan-2-one (PMIND)
Yellow crystal; mp 156–160°C; 72% Yield; IR (KBr)
cm-1
:
2958, 2838, 1705, 1593; 1H-NMR (CDCl3,
Conclusion
300 MHz): d = 3.89 (6H, s, OCH3), 6.96–8.29 (14H,
olefinic protons and ArH); 13C NMR (CDCl3, 500 MHz):
d = 55.49, 113.71, 114.07, 114.12, 119.52, 123.10, 123.16,
127.65, 127.74, 127.87, 128.60, 129.07, 130.05, 131.04,
131.09, 133.04, 133.31, 133.71, 134.03, 134.84, 140.82,
160.44, 160.60, 161.38, 192.76. LC–MS: m/z = 369
(M ? 1)?.
The above discussion reveals that compounds in the BP
(Fig. 2) and IND series (Fig. 3) have anticancer properties.
These heterocycles could be considered as useful templates
for future development and further derivatization to obtain
more potent and selective anticancer agents. Substantial
123

86
Med Chem Res (2011) 20:81–87
1,3-Bis(2-methoxybenzylidene)-indan-2-one (OMIND)
d 3.69 (2H, s), 3.78 (4H, s), 6.76–7.26 (13H, ArH) 7.49
(2H, s, olefinic protons), 9.55 (2H, OH); LC–MS: m/
z = 398 (M ? 1)?.
Yellow amorphous powder; mp 108–112°C; 78% Yield; IR
(KBr) cm-1 3070, 2933, 2836, 1708,1596; 1H-NMR
(DMSO-d6, 400 MHz): d 3.84 (6H, s OCH3), 6.98–7.80
(14H, olefinic protons and ArH); 13C NMR (CDCl3,
500 MHz): d = 55.58, 55.69, 110.24, 110.96, 111.01,
120.23, 123.48, 124.37, 128.56, 129.46, 129.58, 130.99,
158.13, 158.16, 194.41. GC–MS: m/z = 368 (M?).
Acknowledgments The authors wish to thank Dr. Arun Balakrish-
nan, Vice President, External Liason & Screening, Piramal Life
Sciences Limited, Mumbai, for the anticancer screening. We also
thank Dr. R. Sethumadhavan, Professor, School of biosciences and
technology, VIT University, Vellore, for his valuable suggestions.
1-Benzyl-3,5-dibenzylidenepiperidin-4-one (BP)
References
Adams BK, Ferstl EM, Davis MC, Herold M, Kurtkaya S, Camalier
RF, Hollingshead MG, Kaur G, Sausville EA, Rickles FR,
Snyder JP, Liotta DC, Shoji M (2004) Synthesis and biological
evaluation of novel curcumin analogs as anti-cancer and anti-
angiogenesis agents. Bioorg Med Chem 12:3871–3883. doi:
10.1016/j.bmc.2004.05.006
Yellow block Crystal; mp 152–154°C; 97% Yield; IR
1
(KBr) cm-1 3061, 3019, 2798,2755, 1671,1569; H-NMR
(DMSO-d6, 300 MHz): d 3.69 (2H, s), 3.81 (4H, s),
7.18–7.42 (15H, ArH), 7.61 (2H, s, olefinic protons);
GC–MS: m/z = 365 (M?).
Aggarwal BB, Kumar A, Bharti AC (2003) Anticancer potential of
curcumin: preclinical and clinical studies. Anticancer Res
23:363–398. doi:0250-7005/2003
Cell viability assessment was performed by using Cell Counting
Kit (CCK-8), which was purchased from Dojindo Laboratory,
Japan. Experiment design was guided by the CCK-8 technical
manual available at http://www.dojindo.com/newimages/CCK-
8TechnicalInformation.pdf
Chandru H, Sharada AC, Kumar CSA, Rangappa KS (2008)
Antiangiogenic and growth inhibitory effects of synthetic novel
1,5-diphenyl-1,4-pentadiene-3-one-3-yl-ethanone pyridine cur-
cumin analogues on Ehrlich ascites tumor in vivo. Med Chem
Res 17:515–529. doi:10.1007/s00044-008-9095-2
3,5-Bis(4-methoxybenzylidene)-1-benzylpiperidin-4-one
(PMBP)
Yellow block Crystal; mp 150–154°C; 83% Yield; IR
(KBr) cm-1 3063, 2935, 2836, 2743, 1668, 1577; 1H-NMR
(DMSO-d6, 300 MHz): d 3.71 (2H, s), 3.78 (6H, s, OCH3),
3.85 (4H, s) 6.97–7.89 (15H, olefinic protons and ArH);
LC–MS: m/z = 426 (M ? 1)?.
Das U, Alcorn J, Shrivastav A, Sharma RK, De Clercq E, Balzarini J,
Dimmock JR (2007) Design, synthesis and cytotoxic proper-
ties of novel 1-[4-(2-alkylaminoethoxy)phenylcarbonyl]-3,5-bis
(arylidene)-4-piperidones and related compounds. Eur J Med
Chem 42:71–80. doi:10.1016/j.ejmech.2006.08.002
Dhillon N, Wolf RA, Abbruzzese JL, Hong DS, Camacho LH, Li L,
Braiteh FS, Kurzrock R (2006) Phase II clinical trial of curcumin
in patients with advanced pancreatic cancer. J Clin Oncol
24:14151
Dube D, Kukshal V, Srivastava SK, Tripathi RP, Ramachandran R
(2008) NAD?-dependent DNA ligase (Rv3014c) from M.
tuberculosis: strategies for inhibitor design. Med Chem Res
17:189–198. doi:10.1007/s00044-007-9052-5
3,5-Bis(4-ethoxybenzylidene)-1-benzylpiperidin-4-one
(PEBP)
Yellow needle Crystal; mp 110–114°C; 81% Yield; IR
(KBr) cm-1 3062, 3031, 2764,1670, 1577; 1H-NMR
(DMSO-d6, 300 MHz): d 1.29–1.33 (6H, t, CH2CH3) 3.70
(2H, s), 3.77 (4H, s), 4.01–4.08 (4H, q, OCH2) 6.94–7.39
(13H, ArH) 7.54 (2H, s, olefinic protons); LC–MS: m/z =
454 (M ? 1)?.
Fadda AA, Badria FA, El-Attar KM (2009) Synthesis and evaluation
of curcumin analogues as cytotoxic agents. Med Chem Res. doi:
10.1007/s00044-009-9199-3
3,5-Bis(4-allyloxybenzylidene)-1-benzylpiperidin-4-one
(PABP)
Gafner SK, Lee SK, Cuendet M, Barthelemy S, Vergnes L, Labidalle
S, Mehta RG, Boone CW, Pezzuto JM (2004) Biologic
evaluation of curcumin and structural derivatives in cancer
chemoprevention model systems. Phytochemistry 65:2849–
2859. doi:10.1016/j.phttochem.2004.08.008
Jing-yan T, Guo L, Yan-yun G, Hong-li Z, Wen-zhong Z, Xiao W,
Hong-da Z, Tian-hong L, Min L (2006) Role and mechanism of
rosiglitazone on the impairment of insulin secretion induced by
free fatty acids on isolated rat islets. Chin Med 119(7):574–580
Karunagaran D, Rashmi R, Kumar TR (2005) Induction of apoptosis
by curcumin and its implications for cancer therapy. Curr Cancer
Drug Target 5:117–129. doi:10.2174/1568009053202081
Lakshmi S, Dhanya GS, Joy B, Padmaja G, Remani P (2008)
Inhibitory effect of an extract of Curcuma zedoariae on human
cervical carcinoma cells. Med Chem Res 17:335–344. doi:
10.1007/s00044-007-9069-9
Yellow Crystal; mp 114–116°C; 91% Yield; IR (KBr)
1
cm-1 3063, 3028, 2887, 2743,1670, 1600, 1577; H-NMR
(DMSO-d6, 300 MHz): d 3.70 (2H, s), 3.78 (4H, s),
4.59–4.61 (4H, d, OCH2) 5.24–5.41 (4H, CH2), 5.98–6.04
(2H, CH), 6.94–7.40 (13H, ArH) 7.54 (2H, s, olefinic
protons); MS: m/z = 478 (M ? 1)?.
3,5-Bis(3-hydroxybenzylidene)-1-benzylpiperidin-4-one
(MHBP)
Pale Yellow Crystal; mp 180–184°C; 83% Yield; IR (KBr)
1
cm-1 3299, 2772,1666; H-NMR (DMSO-d6, 300 MHz):
123

Med Chem Res (2011) 20:81–87
87
Li N, Cehn X, Liao J, Yang G, Wang S, Jossephson Y, Han C, Chen J,
Huang MT, Yang CS (2002) Inhibiton of 7,12-dimethyl-
benz[a]anthracene (DMBA)-induced oral carcinogenesis in
hamsters by tea and curcumin. Carcinogenesis 23:1307–1313.
doi:10.1093/carcin/23.8.1307
Liang G, Li X, Chen L, Yang S, Wu X, Studer E, Gurley E, Hylemon
PB, Ye F, Li Y, Zhou H (2008a) Synthesis and anti-inflamma-
tory activities of mono-carbonyl analogues of curcumin. Bioorg
Med Chem Lett 18:1525–1529. doi:10.1016/j.bmcl.2007.12.068
Liang G, Yang S, Jiang L, Zhao Y, Shao L, Xiao J, Ye F, Li Y, Li X
(2008b) Synthesis and anti-bacterial properties of mono-car-
bonyl analogues of curcumin. Chem Pharm Bull 56(2):162–167.
doi:10.1248/cpb.56.162
Osawa T, Sugiyama Y, Inayoshi M, Kawakishi S (1995) Antioxida-
tive activity of tetrahydrocurcuminoids. Biosci Biotechnol
Biochem 59:1609–1612 PMID: 8520105
Panchatcharam M, Miriyala S, Gayathri VS, Suguna L (2006)
Curcumin improves wound healing by modulating collagen and
decreasing reactive oxygen species. Mol Cell Biochem
290:87–96. doi:10.1007/s11010-006-9170-2
Pati HN, Das U, Das S, Bandy B, Clercq ED, Balzarini J, Kawase M,
Sakagami H, Quail JW, Stables PJ, Dimmock JR (2009) The
cytotoxic properties and preferential toxicity to tumour cells
displayed by some 2,4-bis(benzylidene)-8-methyl-8-azabicyclo
[3.2.1] octan-3-ones and 3,5-bis(benzylidene)-1-methyl-4-pip-
eridones. Eur J Med Chem 44:54–62. doi:10.1016/j.ejmech.
2008.03.015
RCSB Protein Data Bank. Solution structure of the catalytic domain
of mapk phosphatase pac-1: insights into substrate-induced
enzymatic activation. Receptor 1m3g available at http://www.
rcsb.org/pdb/explore/explore.do?structureId=1M3G
Santo RD, Costi R, Artico M, Ragno R, Greco G, Novellino E,
Marchand C, Pommier Y (2005) Design, synthesis and biolog-
ical evaluation of heteroaryl diketohexenoic and diketobutanoic
acids as HIV-1 integrase inhibitors endowed with antiretroviral
activity. IL Farmaco 60:409–417. doi:10.1016/j.farmac.2005.
03.008
Wu J, Jin YJ, Calaf GM, Huang WL, Yin Y (2007) PAC1 is a direct
transcription target of E2F-1 in apoptotic signaling. Oncogene
26(45):6526–6535. doi:10.1038/sj.onc.1210484
PatchDock Server (2008) An automatic server for molecular docking.
http://bioinfo3d.cs.tau.ac.il/PatchDock/
Pati HN, Das U, Quail JW, Kawase M, Sakagami H, Dimmock JR
(2008) Cytotoxic 3,5-bis(benzylidene)piperidin-4-ones and
N-acyl analogs displaying selective toxicity for malignant cells.
Eur J Med Chem 43:1–7. doi:10.1016/j.ejmech.2007.03.010
Zeng JH, Xu GB, Chen X (2009) Application of the chromatograhic
fingerprint for quality control of essential oil from GuangXi
Curcuma kwangsiensis. Med Chem Res 18:158–165. doi:
10.1007/s00044-008-9115-2
123