Synthesis of diethylamino-curcumin mimics with substituted triazolyl groups and their sensitization effect of TRAIL against brain cancer cells

Article abstract of DOI:10.1016/j.bmcl.2014.05.098

A newly designed curcumin mimic library (11a-11k) with 2-ethylamino groups in a chalcone structure and variously substituted triazole groups as side chains was synthesized using the Huisgen 1,3-cycloaddition reaction between various alkynes (a-k) and an intermediate (10), with CuSO₄ and sodium ascorbate in a solution mixture of chloroform, ethanol, and water (5:3:1) at room temperature for 5 h. In the lactate dehydrogenase (LDH) release assay involving co-treatment with tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) and/or synthetic curcumin derivatives using TRAIL-resistant human CRT-MG astroglioma cells, the novel curcumin mimic library was found to effectively stimulate the cytotoxicity of TRAIL, causing mild cytotoxicity when administered alone. In particular, 11a and 11j are promising candidates for TRAIL-sensitizers with potential use in combination chemotherapy for brain tumors.

Full text of DOI:10.1016/j.bmcl.2014.05.098

Accepted Manuscript
Synthesis of diethylamino-curcumin mimics with substituted triazolyl groups
and their sensitization effect of TRAIL against brain cancer cells
Youngchel Ahn, Sangtae Oh, Seong Jun Lee, Byong-Gon Park, Yoon-Sun Park,
Woon-Seob Shin, Hyuk-Jai Jang, Jin-Hoon Park, Dae Ho Kwon, Seokjoon Lee
PII:
S0960-894X(14)00607-6
DOI:
http://dx.doi.org/10.1016/j.bmcl.2014.05.098
BMCL 21712
Reference:
Bioorganic & Medicinal Chemistry Letters
To appear in:
Received Date:
Revised Date:
Accepted Date:
4 April 2014
26 May 2014
29 May 2014
Please cite this article as: Ahn, Y., Oh, S., Lee, S.J., Park, B-G., Park, Y-S., Shin, W-S., Jang, H-J., Park, J-H.,
Kwon, D.H., Lee, S., Synthesis of diethylamino-curcumin mimics with substituted triazolyl groups and their
sensitization effect of TRAIL against brain cancer cells, Bioorganic & Medicinal Chemistry Letters (2014), doi:
http://dx.doi.org/10.1016/j.bmcl.2014.05.098
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Synthesis of diethylamino-curcumin mimics with substituted
triazolyl groups and their sensitization effect of TRAIL against
brain cancer cells
Youngchel Ahna† , Sangtae Ohb† , Seong Jun Leeb, Byong-Gon Parkc, Yoon-Sun Parkd,
Woon-Seob Shind, Hyuk-Jai Jange, Jin-Hoon Parkf, Dae Ho Kwond*, Seokjoon Leeg*
a Department of Hematology and oncology, Gangneung Medical Center, University of Ulsan College of Medicine,
Gangneung 210-711, Republic of Korea
bDepartment of Basic Science, Kwandong University College of Medicine, Gangneung 210-701, Republic of Korea
cDepartment of physiology, Kwandong University College of Medicine, Gangneung 210-701, Republic of Korea
dDepartment of Microbiology, Kwandong University College of Medicine, Gangneung 210-701, Republic of Korea
eDepartment of Surgery, Gangneung Medical Center, University of Ulsan College of Medicine, Gangneung 210-711,
Republic of Korea
fDepartment of Neurosurgery, Gangneung Medical Center, University of Ulsan College of Medicine, Gangneung 210-711,
Republic of Korea
gDepartment of Pharmacology, Kwandong University College of Medicine, Gangneung 210-701, Republic of Korea
This is where the receipt/accepted dates will go; Received Month XX, 2000; Accepted Month XX, 2000 [BMCL RECEIPT]
Abstract— A newly designed curcumin mimic library (11a-11k) with 2-ethylamino groups in a chalcone structure and variously
substituted triazole groups as side chains was synthesized using the Huisgen 1,3-cycloaddition reaction between various alkynes (a–k)
and an intermediate (10), with CuSO4 and sodium ascorbate in a solution mixture of chloroform, ethanol, and water (5:3:1) at room
temperature for 5h. In the lactate dehydrogenase (LDH) release assay involving co-treatment with tumor necrosis factor (TNF)-related
apoptosis-inducing ligand (TRAIL) and/or synthetic curcumin derivatives using TRAIL-resistant human CRT-MG astroglioma cells, the
novel curcumin mimic library was found to effectively stimulate the cytotoxicity of TRAIL, causing mild cytotoxicity when administered
alone. In particular, 11a and 11j are promising candidates for TRAIL-sensitizers with potential use in combination chemotherapy for
brain tumors.
Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF superfamily of
cytokines. Members of the TNF family contain highly conserved carboxyl-terminal domains and induce receptor
trimerization to transduce intracellular signaling.1 TRAIL can induce apoptotic cell death through caspase-dependent
mechanisms.1,2 TRAIL binds to four different receptors, two of which, death receptor 4 and 5 (DR4 and DR5
*
Corresponding authors: Tel.: +82-33-649-7476; Fax: +82-33-641-1074, E-mail address: dkwon@kd.ac.kr (D. Kwon);
Tel.: +82-33-649-7476; Fax: +82-33-641-1074, E-mail address: sjlee@kd.ac.kr (S. Lee); †These authors are equally
contributed on this work.

respectively), induce apoptosis. However, decoy receptors for TRAIL, DcR1 and DcR2, which lack the cytoplasmic
death domain for transducing apoptotic death signals, protect cells from TRAIL-induced cell death by interfering with
signaling through DR4 and DR5.2-4 Transformed tumor cells are generally believed to be more susceptible to TRAIL-
mediated cell death owing to the selective loss of decoy receptors.5
Glioblastoma multiforme (GBM) is one of the most aggressive forms of human malignant brain tumors and has a
high mortality rate.6,7 It is characterized by rapid growth, extensive invasiveness and robust neo-angiogenesis. GBM is
refractory to all of the current therapeutic approaches including surgery, radiotherapy, and chemotherapy with drugs
such as temozolomide (TMZ). Therefore, there is an urgent need for new chemo-therapeutic strategies to effectively
treat GBM. In this respect, TRAIL is a promising drug target. TRAIL has been shown to exert strong antitumor
activity on intracranial malignant glioma xenografts in athymic mice.8 It showed synergistic cytotoxicity against
human astrocytoma or neuroblastoma in vitro in combination with chemotherapeutic agents such as silibinin,9
bortezomib,10 and the anti-diabetic drug troglitazone.11 Co-treatment with a chemo-sensitizer and TRAIL is more
O
O
O
O
R1
H3CO
HO
H3CO
HO
OCH3
OH
H3CO
HO
N
N
H3C
1
4
R
H
N
H
N
R
S
O2
R
3 R1:
2 R1:
O
N
N
O
N
O
N
R2
R3
N
N
R
R
N
5 R2: -OCH3; R3: -OH
6 R2: -OH; R3: -OCH3
7
efficient to treat against GBM than is treatment with TRAIL alone.11
Throughout our decade of efforts to discover drug candidates based on natural products and structural mimics
libraries, curcumin (diferuloyl methane, 1) has consistently provided better-than-expected results. Curcumin (1), an
important constituent of the root of Curcuma longa L., has versatile and useful biological properties. It shows anti-
inflammatory,12 antioxidant,13 antiviral,14 chemopreventive,15 anti-infective,16 and wound-healing properties.17 Based
on the basic biological properties of curcumin, we previously synthesized a curcumin mimic library and reported
improved biomedical properties. For example, curcumin mimics (2) possessing alkyl amide and aryl amide functional
groups inhibit angiogenesis18 and reverse multidrug resistance (MDR).19,20 Sulfonyl amide-linked curcumin
derivatives (3) exhibit a vasodilatation effect on the basilar artery After K+-induced contraction.21
Figure 1. Structures of curcumin and synthetic curcumin mimic derivatives
The structure-activity relationships of the curcumin mimics indicate that the diversification of biological properties
comes from the right side functionality attached to the feruloyl scaffold. For example, amide- and sulfonyl amide-
linked compounds (2 and 3) showed weak cytotoxicity whereas curcumin mimics with substituted benzimidazole
groups (4) exhibited strong cytotoxicity against various cancer cells22 and multidrug-resistant cancer cells.23 In

addition, we reported that substituted triazolyl curcumin mimics (5 and 6) synthesized through Cu(I)-catalyzed
Huisgen 1,3-cycloaddition exhibited moderate to strong inhibitory activity against the osteoclastogenesis induced by
the receptor activator of NF-κB ligand (RANKL)24 (Fig. 1).
When considering our previous reports for the structure-activity relationship of diverse curcumin mimic libraries, it
is obvious that curcumin (1) can be used as a lead compound for discovering TRAIL sensitizers for use in
combination therapy with TRAIL. Gautam et al reported that co-treatment of curcumin (1. 10 µM) and TRAIL (20
ng/ml) enhanced cytotoxicity against LNCaP cells (prostate cancer cells) 2- to 3-fold, by activating caspase-3.25 Kwon
et al also discovered that curcumin increases the sensitivity of human renal cancer cells to TRAIL, inducing DR5
expression and generating reactive oxygen species.26 Moreover, Gautam et al reported that co-treatment with
curcumin (20 µM) and TRAIL (5 ng/ml) induced cytotoxicity by 60% in U251MG cells and 45% in U87MG cells
via cleavage of procaspases-3 and -8.27 Although its potency needs to be further improved for use in clinical treatment,
we can postulate that curcumin-derived derivatives might be novel TRAIL sensitizers in the combination
chemotherapy against human brain tumors. Based on previous reports, we synthesized a novel curcumin mimic
library and investigated its usefulness for combination therapy with TRAIL in the treatment of GBM.
O
O
O
N3
b)
a)
H
N3
+
R
N
N
8
9
10
F
OH
N
O
N
c
a
d
b
N
R
R:
(CH2)4CH3
OCH3
N
11a - 11k
g
e
f
F
F3C
Cl
Br
F
j
k
h
i
Scheme 1. Reagents and conditions: (a) 40% KOH, EtOH, RT, 10 h; (b) Sodium ascorbate (2.5 eq.), CuSO4 (1 eq.), chloroform:EtOH:H2O =
5:3:1, RT, 5 h.; isolated yields for 10, 58%; 11a, 30%; 11b, 80%; 11c, 94%; 11d, 45%; 11e, 61%; 11f, 48%; 11g, 55%; 11h, 88%; 11i, 74%;
11j, 92%; 11k, 56%.
Unlike the previous curcumin mimic library (2-6) shown in Fig 1, we introduced a diethylamino group at the 4-
position of the chalcone structure, in place of the methoxy and hydroxyl group of curcumin to add bulkiness and an
electronic effect. To obtain a synthetic intermediate (10) for the curcumin mimic library (11a-11k), we started with
the aldol reaction of commercially available 4-(diethylamino)benzaldehyde (8) with 3-azidoacetophenone (9)
synthesized by the previously shown method24 in the presence of a basic catalyst (40% KOH) in ethanol at room

temperature for 10h. The α,β-unsaturated double bond in the intermediate (10) was confirmed to the trans
configuration because of a large coupling constant (J = 15.7 Hz) between its two protons. To construct a curcumin
mimic library with substituted triazolyl groups (11a-11k), we attempted the Huisgen 1,3-cycloaddition reaction
between various alkynes (a–k) and the intermediate (10), with CuSO4 and sodium ascorbate in a solution mixture of
chloroform, ethanol, and water (5:3:1) at room temperature for 5h.24, 28 The yields of triazole products are summarized
in Scheme 1.
As shown in previous reports,25-27 curcumin (1) can stimulate the cytotoxic potency of TRAIL against various
cancer cells. Based on the those backgrounds, we sought to determine whether the curcumin mimic library (11a-11k)
could enhance TRAIL-mediated cell death against human CRT-MG astroglioma cells by using the lactate
dehydrogenase (LDH) release assay.29 The results are summarized in Fig 2.
Figure 2. The cytotoxic effect of TRAIL and/or curcumin (1) and curcumin mimics library (10, 11a-11k). (A) The cell death percentage of human
CRT-MG astroglioma cells is due to treatment with TRAIL concentration of 12.5 ng/ml to 250 ng/ml for 24h. (B) Human CRT-MG astroglioma
cells were treated with TRAIL (25 ng/ml) and/or all tested drugs (10 µM). Data are presented as means ± SD. Levels of significance for
comparisons between samples were determined using Student’s t-test distribution.
First, we tested the cytotoxicity of various concentrations of TRAIL to determine whether human CRT-MG
astroglioma cells are resistant to TRAIL treatment. Although TRAIL induced cell death in a dose-dependent manner
within the range of 12.5 ng/ml to 100 ng/ml, the cytotoxic effect did not increase further with TRAIL concentration
above 100 ng/ml, which means that human CRT-MG astroglioma cells are resistant to treatment with TRAIL as an
antitumor agent (Fig, 2A). Secondly, before evaluating the TRAIL sensitization effect of the synthesized curcumin
mimic derivatives, their cell cytotoxicity was measured by applying a concentration of 10 µM to CRT-MG cells for
24 h. As shown in Fig. 2B (white bar), curcumin and other tested compounds except synthetic intermediate (10),
showed low toxicity, less than 20%. Several compounds (11b, 11d-11g, 11j, and 11k) did not induce apoptosis at all
at the tested concentration. Considering their low cytotoxicity, if co-treatment with the curcumin mimics and TRAIL
increase apoptosis of TRAIL-resistant cancer cells, we can postulate that the increase activity is due to sensitization
effect of the curcumin derivatives, and not from their direct cytotoxicity. For example, synthetic intermediate (10), a
concentration of 10 µM, enhanced TRAIL-induced cell death from 27.8% to 78.3%. In this case, the enhancement
was attributable to the cytotoxicity of 10, which inhibited CRT cell proliferation to 55.6%. However, curcumin mimic

library showed a sensitization effect of TRAIL without or with only slight cytotoxicity. 2-Hydroxypropantriazolyl
chalcone (11a) and benzenetriazolyl chalcone (11c) similarly increased the sensitivity of TRAIL about 2.5-fold, but
their cell cytotoxicity was very low (13.3% and 14.3%, respectively). We can conclude that they sensitize human
CRT-MG astroglioma cells to TRAIL. Moreover, o-trimethylphenyltriazolyl chalcone (11h) and m-
chlorophenyltriazolyl chalcone (11i) effectively increased the anticancer activity of TRAIL without producing cell
cytotoxicity themselves (11h and 11i). The other derivatives (11b, 11d-11g, 11j, and 11k) showed no inhibitory
activity against cancer cells and slightly sensitized the cells to TRAIL. This suggests that they cannot interact with the
receptors that influence the sensitization to TRAIL.
Based on a preliminary analysis of structure-activity relationships, curcumin mimics possessing an electron
donating group cannot influence cell death and the sensitization of TRAIL simultaneously. Interaction of active
compounds with cancer cells can influence the sensitization of cancer cells to TRAIL, as well as cell viability.
Figure 3. Dose-dependent cytotoxic effects of combination treatment of TRAIL and selected curcumin mimics (11a, 11c, 11h, and 11j). Data are
presented as means ± SD. Levels of significance for comparisons between samples were determined using Student’s t-test distribution.
Finally, we tested the cytotoxicity of TRAIL (25 ng/ml) against CRT-MG cells with co-treatment of selected
curcumin mimics (11a, 11c, 11h, and 11j) at variable concentrations. The results showed that 11a and 11j were the
most promising TRAIL sensitizers among in curcumin mimic library because they showed low cell toxicity (under
20% in cell death percentage) at a high concentration (50 µM). Although combination treatment of TRAIL with high
concentrations (50 µM) of 11c and 11h showed maximum cell death, it is predicted that most of the increment in
cytotoxicity comes from the increasing cytotoxicity of curcumin derivatives (11c and 11h). However, 11c and 11h are
potential candidates for TRAIL sensitizers if they are used at concentrations under 10 µM.
In conclusion, we synthesized a novel curcumin mimic library (11a-11k) by using the Huisgen 1,3-cycloaddition

reaction between azido chalcone intermediate (10) having 2-ethylamino group and various alkynes (a-k) with the
intention of discovering new TRAIL sensitizer candidates. Based on the LDH release assay of co-treatment TRAIL
and/or synthetic curcumin derivatives by using TRAIL-resistance human CRT-MG astroglioma cells, we discovered
that a 2-ethylamino-curcumin mimic library possessing various substituted triazole moieties exhibited a sensitization
effect of TRAIL without or with slight cytotoxicity. Four compounds (11a, 11c, 11h, and 11j) were promising
TRAIL-sensitizers with the potential for application in combination chemotherapy of brain tumors. Based on the
preliminary structure–activity relationships, the curcumin mimic library having 2-ethylamino and substituted triazol
groups will be a promising template for developing novel TRAIL sensitizers as anticancer agents.
Acknowledgement
This work was funded by Gangnung Asan Hospital (Biomedical Research Center Promotion Fund).
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28. NMR data for 11a: 1H-NMR (300 MHz, CDCl3): δ 8.27 (t, J = 1.7 Hz, 1H), 8.01 (m, 3H), 7.83 (d, J = 15.4 Hz, 1H),
7.61 (t, J = 7.9 Hz, 1H), 7.53 (d, J = 8.9 Hz, 2H), 7.30 (d, J = 15.3 Hz, 1H), 6.65 (d, J = 9.0 Hz, 2H), 3.42 (q, J = 7.1 Hz,
4H), 1.73 (s, 6H), 1.20 (t, J = 7.0 Hz, 6H) ppm; 13C-NMR (75 MHz, CDCl3): δ 188.9, 150.0, 147.2, 140.7, 137.3, 131.1,
129.9, 128.2, 123.8, 121.4, 119.8, 115.1, 111.2, 68.6, 44.5, 30.4, 12.5 ppm.; 11b: 1H-NMR (300 MHz, CDCl3): δ 8.28 (t, J =
1.7 Hz, 1H), 8.04 (m, 3H), 7.85 (d, J = 15.4 Hz, 1H), 7.65 (t, J = 8.0 Hz, 1H), 7.55 (d, J = 9.0 Hz, 2H), 7.32 (d, J = 15.3 Hz,
1H), 6.67 (d, J = 8.9 Hz, 2H), 5.87 (s, 1H), 5.20 (t, J = 1.6 Hz, 1H), 3.43 (q, J = 7.1 Hz, 4H), 2.21 (s, 3H), 1.21 (t, J = 7.1
Hz, 6H) ppm.; 13C-NMR (75 MHz, CDCl3): δ 188.9, 150.0, 149.5, 147.2, 140.7, 137.3, 133.0, 131.1, 129.9, 128.1, 123.7,
121.5, 119.6, 117.6, 115.2, 113.4, 111.3, 44.5, 20.6, 12.6 ppm.; 11c: 1H-NMR (300 MHz, CDCl3): 8.35 (t, J = 1.7 Hz, 1H),
8.33 (s, 1H), 8.07 (m, 2H), 7.93 (m, 2H), 7.87 (m, 1H), 7.67 (t, J = 7.9 Hz, 1H), 7.56 (d, J = 8.9 Hz, 2H), 7.45 (m, 4H), 6.68
(d, J = 9.0 Hz, 2H), 3.43 (q, J = 7.1 Hz, 4H), 1.21 (t, J = 7.1 Hz, 6H) ppm.; 13C-NMR (75 MHz, CDCl3): δ 188.9, 150.2,
147.2, 140.8, 137.8, 131.1, 130.1, 130.0, 128.9, 128.5, 128.3, 125.9, 123.8, 121.7, 119.7, 115.2, 111.3, 44.5, 12.6 ppm.;
11d: 1H-NMR (300 MHz, CDCl3): δ 8.33 (t, J = 1.7 Hz, 1H), 8.28 (s, 1H), 8.07 (dd, J = 1.7, 8.3 Hz, 2H), 7.90 (m, 3H), 7.65
(t, J = 7.9 Hz, 1H), 7.54 (d, J = 9.0 Hz, 2H), 7.32 (d, J = 15.4 Hz, 1H), 7.15 (t, J = 8.7 Hz, 2H), 6.65 (d, J = 9.0 Hz, 2H),
3.42 (q, J = 7.1 Hz, 4H), 1.20 (t, J = 7.1 Hz, 6H) ppm.; 13C-NMR (75 MHz, CDCl3): δ188.7, 164.4 (d, J = 246.2 Hz), 150.0,
147.6, 147.2, 140.7, 137.2, 131.1, 129.9, 128.2, 127.6, 127.5, 126.3 (d, J = 2.9 Hz), 123.6, 121.4, 119.6, 117.4, 116.0,
115.7, 115.1, 111.2, 44.5, 12.5 ppm.; 11e: 1H-NMR (300 MHz, CDCl3): δ 8.33 (t, J = 1.8 Hz, 1H), 8.28 (s, 1H), 8.08 (dd, J
= 2.0, 8.0 Hz, 2H), 7.91 (m, 3H), 7.67 (t, J = 8.1 Hz, 1H), 7.55 (d, J = 9.0 Hz, 2H), 7.32 (d, J = 15.4 Hz, 1H), 7.16 (t, J = 8.6
Hz, 2H), 6.68 (d, J = 8.9 Hz, 2H), 3.42 (q, J = 7.1 Hz, 4H), 2.36 (s, 3H), 1.21 (t, J = 7.1 Hz, 6H) ppm.; 13C-NMR (75 MHz,
CDCl3): δ188.7, 161.2, 150.1, 147.7, 147.2, 140.8, 137.2, 131.1, 130.0, 128.3, 127.7, 127.6, 126.3, 123.7, 121.5, 119.7,
117.4, 116.1, 115.8, 115.1, 111.3, 44.5, 29.7, 12.6 ppm.; 11f: 1H-NMR (300 MHz, CDCl3): δ 8.33 (t, J = 1.8 Hz, 1H), 8.23
(s, 1H), 8.04 (dd, J = 2.0, 7.4 Hz, 2H), 7.84 (m, 3H), 7.63 (t, J = 7.8 Hz, 1H), 7.53 (d, J = 8.9 Hz, 2H), 7.31 (d, J = 15.3 Hz,
1H), 6.98 (d, J = 8.9 Hz, 2H), 6.64 (d, J = 9.0 Hz, 2H), 3.84 (s, 3H), 3.40 (q, J = 7.1 Hz, 4H), 1.97 (t, J = 7.1 Hz, 3H) ppm.;
13C-NMR (75 MHz, CDCl3): δ188.8, 159.8, 150.0, 148.4, 147.1, 140.7, 137.3, 131.1, 129.9, 128.1, 127.1, 123.6, 122.7,
121.5, 119.6, 116.8, 115.1, 114.3, 111.2, 55.3, 44.5, 12.5 ppm.; 11g: 1H-NMR (300 MHz, CDCl3): δ 8.34 (s, 1H), 8.28 (s,
1H), 8.06 (d, J = 7.9 Hz, 2H), 7.84 (m, 3H), 7.65 (t, J = 8.0 Hz, 1H), 7.54 (d, J = 8.9 Hz, 2H), 7.29 (m, 3H), 6.66 (d, J = 8.9
Hz, 2H), 3.42 (q, J = 7.0 Hz, 4H), 2.64 (t, J = 7.5 Hz, 2H), 1.65 (m, 2H), 1.34 (m, 4H), 1.20 (t, J = 7.1 Hz, 6H), 0.91 (t, J =
7.0 Hz, 3H) ppm.; 13C-NMR (75 MHz, CDCl3): δ 188.9, 150.0, 147.1, 143.5, 140.7, 137.3, 131.1, 129.9, 128.9, 128.1,

1
127.4, 125.8, 123.7, 121.5, 119.6, 117.2, 115.2, 111.3, 44.5, 35.7, 31.4, 31.0, 22.5, 14.0, 12.6 ppm.; 11h: H-NMR (300
MHz, CDCl3): δ 8.38 (t, J = 1.8 Hz, 1H), 8.29 (s, 1H), 8.05 (m, 3H), 7.84 (d, J = 15.3 Hz, 1H), 7.80 (d, J = 7.8 Hz, 1H),
7.68 (t, J = 7.9 Hz, 2H), 7.56 (d, J = 9.0 Hz, 2H), 7.32 (d, J = 15.3 Hz, 2H), 6.66 (d, J = 9.0 Hz, 2H), 3.42 (q, J = 7.1 Hz,
4H), 1.20 (t, J = 7.1 Hz, 6H) ppm.; 13C-NMR (75 MHz, CDCl3): δ 188.8, 150.0, 147.2, 145.1, 140.9, 137.1, 132.1, 131.8,
131.1, 130.0, 128.6, 128.4, 126.3 (q, J = 5.9 Hz), 125.2, 123.9, 121.5, 121.0 (q, J = 5.3 Hz), 120.0, 115.2, 111.3, 44.5, 29.7,
1
12.5 ppm.; 11i: H-NMR (300 MHz, CDCl3): δ 8.34 (s, 2H), 8.06 (m, 2H), 7.93 (t, J = 1.8 Hz, 1H), 7.86 (d, J = 15.4 Hz,
1H), 7.80 (m, 1H), 7.66 (t, J = 7.9 Hz, 1H), 7.54 (d, J = 8.9 Hz, 1H), 7.39 (t, J = 7.9 Hz, 1H), 7.34 (m, 2H), 7.27 (d, J = 9.2
Hz, 1H), 6.66 (d, J = 8.9 Hz, 2H), 3.42 (q, J = 7.1 Hz, 4H), 1.20 (t, J = 7.1 Hz, 6H) ppm.; 13C-NMR (75 MHz, CDCl3): δ
188.7, 150.1, 147.3, 140.8, 137.1, 134.9, 131.8, 131.1, 130.2, 130.0, 128.5, 128.4, 125.9, 123.9, 123.7, 121.4, 119.7, 118.0,
115.0, 111.3, 44.5, 12.6 ppm.; 11j: 1H-NMR (300 MHz, CDCl3): δ 8.32 (s, 2H), 8.06 (m, 2H), 7.85 (d, J = 15.5 Hz, 1H),
7.80 (m, 2H), 7.67 (t, J = 7.9 Hz, 1H), 7.60 (d, J = 8.5 Hz, 2H), 7.55 (d, J = 9.0 Hz, 2H), 7.32 (d, J = 15.3 Hz, 1H), 6.66 (d,
J = 8.9 Hz, 2H), 3.42 (q, J = 7.1 Hz, 4H), 1.21 (t, J = 7.1 Hz, 6H) ppm.; 13C-NMR (75 MHz, CDCl3) δ 188.8, 150.1, 147.5,
147.3, 140.8, 137.2, 132.1, 131.1, 130.0, 129.0, 128.4, 127.4, 123.7, 122.4, 119.7, 117.7, 115.1, 111.3, 44.5, 12.6 ppm.;
11k: 1H-NMR (300 MHz, CDCl3): δ 8.33 (m, 2H), 8.07 (m, 2H), 7.84 (d, J = 15.4 Hz, 1H), 7.68 (t, J = 8.0 Hz, 1H), 7.55 (d,
J = 8.9 Hz, 2H), 7.47 (m, 2H), 7.32 (d, J = 15.3 Hz, 1H), 6.82 (m, 1H), 6.67 (d, J = 9.0 Hz, 2H), 3.43 (q, J = 7.1 Hz, 4H),
1.21 (t, J = 7.1 Hz, 6H) ppm.; 13C-NMR (75 MHz, CDCl3) δ 188.7, 165.1 (d, J = 246.2 Hz), 161.9 (d, J = 248.0 Hz), 150.1,
147.3, 140.9, 137.0, 133.2, 131.1, 130.1, 128.5, 123.8, 121.4, 119.7, 118.4, 115.0, 111.3, 108.9, 108.8(d, J = 9.0 Hz), 108.5,
103.7 (d, J = 25.4 Hz), 44.5, 12.6 ppm.
29. Kwon, D.; Choi, C.; Lee, J.; Kim, K. O.; Kim, S. J.; Kim, J. D.; Choi, I. H. J. Neuroimmunol. 2001, 113, 1.; LDH
(lactic dehydrogenase) release assay: Cell cytotoxicity was measured using the LDH cytotoxicity detection kit (Takara,
Otsu, Shiga, Japan). 100 µl of cell-free supernatant was used for LDH cytotoxicity assay by incubation with 22.9 mM
pyruvate and 1 mM β-NADH in 0.2 M LDH buffer, pH 7.4. The soluble reaction product was quantified
spectrophotometrically at 490 nm using an ELISA reader VERSAmax (Molecular Devices, Sunnyvale, CA). Total LDH
activity was determined by lysing control cells with 1% Triton X-100 for 30 min. LDH release was expressed as the
percentage of total LDH activity.

Synthesis of diethylamino-curcumin mimics with substituted triazolyl groups and their sensitization effect
of TRAIL against brain cancer cells
Youngchel Ahn, Sangtae Oh, Seong Jun Lee, Byong-Gon Park, Yoon-Sun Park, Woon-Seob Shin, Hyuk-Jai
Jang, Jin-Hoon Park, Dae Ho Kwon*, and Seokjoon Lee*
N
O
O
N
Huisgen
1,3-cycloaddition
N3
N
R
+
R
N
N
alkyne a-k
10
11a-11k