Synthesis of chalcone derivatives as potential anti-diabetic agents

Article abstract of DOI:10.1016/j.bmcl.2012.04.108

Chalcones bearing electron donating or electron withdrawing substitutions were prepared and their glucose uptake activity was evaluated. Chalcone derivatives were synthesized in one step protocol with high purity and yield. Chalcones with chloro, bromo, iodo and hydroxy substitutions at position 2 on A-ring exhibited the highest activity with glucose medium concentration (210 to 236 mg/dl) compared to pioglitazone and rosiglitazone (230 and 263 mg/dl, respectively). Also chalcones with iodo substitution at position 3 on A-ring were comparably active (≤ 238 mg/dl). The structure-activity relationship of the tested chalcones was studied and the findings were supported statistically.

Full text of DOI:10.1016/j.bmcl.2012.04.108

Bioorganic & Medicinal Chemistry Letters 22 (2012) 3912–3915
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Synthesis of chalcone derivatives as potential anti-diabetic agents
Chi-Ting Hsieh a, Tusty-Jiuan Hsieh b, Mohamed El-Shazly a,c, Da-Wei Chuang a, Yi-Hong Tsai a,
a,
Chiao-Ting Yen a, Shou-Fang Wu a, Yang-Chang Wu a,d,e,f, , Fang-Rong Chang
⇑
⇑
a Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung 807, Taiwan
b Department of Medical Genetics, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan
c Department of Pharmacognosy and Natural Products Chemistry, Faculty of Pharmacy, Ain-Shams University, Cairo 11566, Egypt
d School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung 404, Taiwan
e Natural Medicinal Products Research Center, China Medical University Hospital, Taichung 404, Taiwan
f Center for Molecular Medicine, China Medical University Hospital, Taichung 404, Taiwan
a r t i c l e i n f o
a b s t r a c t
Article history:
Chalcones bearing electron donating or electron withdrawing substitutions were prepared and their glu-
cose uptake activity was evaluated. Chalcone derivatives were synthesized in one step protocol with high
purity and yield. Chalcones with chloro, bromo, iodo and hydroxy substitutions at position 2 on A-ring
exhibited the highest activity with glucose medium concentration (210 to 236 mg/dl) compared to piog-
litazone and rosiglitazone (230 and 263 mg/dl, respectively). Also chalcones with iodo substitution at
position 3 on A-ring were comparably active (6 238 mg/dl). The structure–activity relationship of the
tested chalcones was studied and the findings were supported statistically
Received 16 March 2012
Revised 12 April 2012
Accepted 24 April 2012
Available online 30 April 2012
Keywords:
Adipocyte
Aldol condensation
Chalcone
Ó 2012 Elsevier Ltd. All rights reserved.
Diabetes
Structure–activity relationship
Metabolic syndrome and diabetes are growing health issues in
the past decades. The associated complications of these disorders,
such as cardiovascular diseases, peripheral vascular diseases,
stroke, diabetic neuropathy, amputations, renal failure, and blind-
ness result in increasing disability, reducing life expectancy, and
enormous health costs.1 Diabetes mellitus (DM) is a growing prob-
lem that threatens human health and life in both developed and
third world countries. According to reports from the World Health
Organization (WHO), around 250 million people are currently
living with diabetes and this number is expected to be more than
366 million by 2030.2,3 Consequently, the prevention and treat-
ment of diabetes is considered a globally challenging problem.
Prevention and control of diabetes with diet, weight control,
and physical activity are difficult tasks. Treatment of type 2 diabe-
tes mellitus (T2DM) has centered on increasing blood insulin
levels, either by direct insulin administration or using oral drugs
that promote insulin secretion, decrease insulin resistance, or re-
duce the rate of carbohydrate absorption from the gastrointestinal
tract. So far, the major drug categories currently used to treat
T2DM have several side effects, especially for those patients with
liver and renal functional disorders.1,4 Therefore, developing a
new drug category for diabetes is an ultimate goal for improving
life quality of human beings.
Chalcone is a class of open-chain flavonoids that is not only
biosynthesized by plants but also can be prepared synthetically.
The simplest chalcone can be prepared by an aldol condensation
between a benzaldehyde and an acetophenone in the presence of
base.5–7 Chalcones have shown a wide variety of pharmacological
effects, including anti-inflammatory and anticancer activities.5,8
Despite the comprehensive biological studies on chalcones, reports
on their anti-diabetic activity are scarce.5,8–15
Significant advances have been made in the past few years in
the isolation and preparation of several chalcone derivatives. Liu
et al. synthesized a series of chalcone derivatives bearing 2,4-thia-
zolidinedione and benzoic acid moieties which were active against
Gram-positive and Gram-negative bacteria.14 Shukla et al. synthe-
sized chalcone fibrates with anti-dyslipidemic activity.13 Jung et al.
synthesized a group of 2-hydroxychalcones and chalconyl-thiazo-
lidinediones and examined their anti-diabetic activity through
evaluating their binding potential to peroxisome proliferator-acti-
vated receptor gamma (PPAR-c c is a predominant
).11 PPAR-
molecular target for certain anti-diabetic drugs such as insulin-
sensitizing thiazolidinediones (TZDs). In recent structure–activity
relationship studies, it was reported that some chalcone deriva-
tives stimulated expression and exhibited binding affinity to
⇑
Corresponding authors. Tel.: +886 4 220 57153; fax: +886 4 220 60248 (Y.-C.
Wu), tel.: +886 7 312 1101x2162; fax: +886 7 3114773 (F.-R. Chang).
E-mail addresses: yachwu@mail.cmu.edu.tw (Y.-C. Wu), aaronfrc@kmu.edu.tw
(F.-R. Chang).
PPAR-
vonoid family with A, B rings linked by
c.
9,13 Chalcones possess a unique skeleton that belong to fla-
a,b-unsaturated carbonyl
0960-894X/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmcl.2012.04.108

C.-T. Hsieh et al. / Bioorg. Med. Chem. Lett. 22 (2012) 3912–3915
3913
system which is totally different from other anti-diabetic drugs in
the world market (Fig. 1). In our previous report, we evaluated the
anti-atherosclerotic effect of 2-hydroxy-40-methoxychalcone
(AN07, 1i, Table 1) and investigated its mechanism of action.9
The study revealed that the activity is mediated via stimulation
HO
HO
O
NH NH
O
O
OH
S
N
N
H
N
H
N
N
H
NH2
HO
OH
Cl
Metformin
Miglitol
Chlorpropamide
(sulfonylurea)
of PPAR-c mRNA and protein expression in human aortic smooth
(biguanide)
α
( -glucosidase inhibitor)
muscle cells. Therefore, we presumed that chalcone derivatives
could potentially be used as anti-diabetic agents and subjected
for further investigation.
OH
O
O
In this study, cellular glucose uptake activity induced by differ-
ent chalcone derivatives was evaluated. Most of the tested chalcone
derivatives were prepared according to established protocol, and
some of them were obtained commercially (see Supplementary
S
S
N
N
H
HN
N
O
O
N
7
Pioglitazone* (TZDs)
Vildagliptin (DPP-4 inhibitor)
data). Acetophenones bearing hydroxy group and or halogens
O
were reacted with substituted benzaldehydes in the presence of
50% (w/v) KOH/H2O using ethanol as a solvent. Purification was
done using column chromatography and some chalcones such as
those bearing a 4-methoxy group on B-ring can even be recrystal-
lized directly from ethyl acetate-methanol mixture, with accept-
able yields ranging from 60%–80%.16
OH
H
O
O
N
N
N
HN
O
H
O
Meglitinides (glinides)
Rosiglitazone* (TZDs)
Adipose tissues are major sites for postprandial glucose uptake.17
Therefore, in vitro anti-diabetic screening model based on measur-
Figure 1. The structures of six major anti-diabetic drugs. ⁄Used as positive controls.
Table 1
Chalcone derivatives and the value of glucose consumption in culture media
3`
4`
5`
2`
B
R2
3
KOH
R1
R2
R14
2
(50% w/v)
6`
A
H
C2H5OH, 25 °C
5
6
O
O
O
R1 = -H, -OH, F, Cl, Br, I
R2 = -H, -OMe, -OBn, -OCH2O-
A-Ring
B-Ring
40
Glucose (mg/dl)a
A-Ring
B-Ring
Glucose (mg/dl)a
2
3
4
5
30
50
2
3
4
5
30
40
50
1a
1b
1c
1d
1e
1f
1g
1h
1i
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
F
H
H
H
H
H
H
H
H
H
H
H
H
H
H
OH
OH
OH
OH
OH
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
F
Cl
Cl
Br
Br
Br
Br
Br
Br
H
H
H
OCH3
OBn
H
H
H
H
H
OCH3
OBn
H
H
H
H
OCH3
H
H
OBn
OH
–OCH2O–
H
OCH3
H
H
OBn
OH
–OCH2O–
H
OCH3
H
H
OBn
H
H
OCH3
H
H
OCH3
H
H
H
H
H
H
H
253 9.9
261 3.2
261 7.2
285 8.2
274 13.0
263 5.6
252 18.1
269 11.0
283 21.4
264 7.8
256 13.1
260 3.8
267 3.4
279 7.6
273 2.9
248 0.4
274 12.1
283 2.6
249 12.2
297 9.3
236 17.5
282 16.4
266 23.3
253 7.8
254 17.6
260 3.3
256 1.3
252 0.1
259 .3
3e
4a
4b
4c
4d
4e
4f
4g
5a
5b
5c
5d
5e
5f
5g
5h
5i
6a
6b
6c
6d
6e
6f
H
Cl
H
H
H
H
H
H
Br
Br
Br
H
H
H
H
H
H
I
I
I
I
H
H
H
H
H
H
H
H
H
Cl
Cl
Cl
H
H
H
H
H
H
Br
Br
Br
H
H
H
H
H
H
H
I
F
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
OCH3
H
H
H
OCH3
H
H
OCH3
H
H
OCH3
H
H
OCH3
H
H
OCH3
H
H
OCH3
H
OBn
H
H
H
OCH3
H
OCH3
H
H
OCH3
H
H
OCH3
H
H
OCH3
H
H
OCH3
H
H
OCH3
H
OBn
H
H
OCH3
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
285 1.6
234 24.4
291 9.2
287 13.4
255 27.1
295 8.8
293 7.8
272 22.4
249 20.8
230 8.7
249 5.2
299 7.3
248 8.0
262 2.2
295 5.8
261 12.7
257 10.0
223 13.8
210 3.7
210 2.0
249 3.6
238 1.1
294 7.3
233 3.5
246 11.3
292 5.3
299 3.8
274 22.5
310 4.0
294 6.3
263 23.9
230 13.5
H
H
H
H
Cl
Cl
Cl
H
H
H
H
H
H
Br
Br
Br
H
H
H
H
H
H
H
H
I
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
H
H
H
H
H
H
H
1j
1k
1l
1m
1n
1o
1p
1q
1r
1s
2a
2b
2c
2d
2e
2f
2g
2h
2i
3a
3b
3c
3d
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
OCH3
OBn
H
OCH3
H
H
OCH3
H
H
OCH3
H
OBn
H
OCH3
H
I
I
I
H
H
H
6g
6h
6i
OCH3
H
H
OH
OH
OH
F
F
H
H
OCH3
H
OBn
H
OCH3
H
OCH3
H
6j
I
I
6k
Control
OCH3
H
H
H
285 4.4
298 15.5
282 10.1
Insulin (3.2 ꢀ 10ꢁ7 M)
Rosiglitazoneb
H
F
OCH3
Pioglitazoneb
aData are means SD of N = 3 determinations.
bChalcone derivatives, rosiglitazone and pioglitazone were using the same concentrations 30
lg/ml.

3914
C.-T. Hsieh et al. / Bioorg. Med. Chem. Lett. 22 (2012) 3912–3915
Figure 2. Scatterplot of structure–activity relationship. X-axis: substitutions on A and B ring (Ring-Position); Y-axis: culture medium glucose concentration.
Table 2
3T3-L1 adipocytes culture medium was studied. Active compounds
Multi-way ANOVA for chalcones SAR
(2b, 4a, 5b, 6a, 6b and 6c) shared a common feature with substitu-
tion at position 2 of A-ring, suggesting the significance of substitu-
tion at this position for glucose uptake activity. Additionally,
compounds (6e and 6g) with iodo substitution at position 3 on
A-ring also showed great potential in reducing glucose medium
concentration. The SAR of the examined chalcones was studied
and statistical results supported our findings. Currently a series
of detailed mechanistic studies on these active chalcones are under
investigation in our laboratory.
Source
A-Ring
Nparm
DF
Sum of squares
F ratio
Prob > F
20
30
40
50
30
40
5
4
5
3
2
4
5
4
5
3
2
4
6870.2235
2612.6151
1859.3364
1811.7209
1038.6301
799.7002
4.8792
2.3193
1.3205
2.1444
1.8441
0.7099
0.0016*
0.0756
0.2775
0.1117
0.1728
0.5905
B-Ring
Nparm: nonparametric statistics; DF: degree of freedom.
p value <0.05.
*
Acknowledgments
ing glucose consumption after 24 h in culture medium of 3T3-L1
adipocytes was developed.3,18–21 In our preliminary screening
results, it was found that the substitution on A-ring is crucial for pro-
moting cellular glucose consumption. Accordingly, 60 chalcone
derivatives with and without substitutions on A-ring were exam-
ined in our developed model. Two anti-diabetic clinical drugs, piog-
litazone and rosiglitazone were used as positive controls with
culture medium glucose concentrations of 230 and 263 mg/dl,
respectively. Chalcones which lowered glucose level (n = 3) below
240 mg/dl were regarded as active candidates (Table 1). Structure–
activity relationship (SAR) analyses data are shown in the scatter
plot (Fig. 2). The X-axis of the scatter plot represents different substi-
tutions on A and B rings of the tested chalcones, and the Y-axis rep-
resents the effect of substitution on culture medium glucose
concentration. Chalcones with hydroxy (2b), chloro (4a), bromo
(5b) and iodo (6a, 6b and 6c) substitutions at position 2 on A-ring
exhibited good activity with culture glucose medium concentra-
tions ranging from 210 to 236 mg/dl. Additionally, chalcones with
iodo substitutionat position 3 on A-ring (6e and 6g) were active with
comparable results (238 and 233 mg/dl, respectively). It is notewor-
thy to state that methoxy or benzyloxy substitution on B ring also
positively affected chalcones activity (2b and 2c, 5a, 5b, and 5c as
well as 6g and 6h).
This work was supported by grants from the National Science
Council, Taiwan (Grant Nos. NSC 98-2323-B-037-004- and 99-
2323-B-037-002-).
Supplementary data
Supplementary data associated with this article can be found,
in the online version, at http://dx.doi.org/10.1016/j.bmcl.2012.
04.108.
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JMP 9.0.0 (SAS Institute, Cary, NC). The results showed that substi-
tution (fluoro, chloro, bromo, iodo, hydroxy and hydrogen) at posi-
tion 2 of A-ring, significantly affected the glucose uptake activity in
the cell model (p = 0.0016; Table 2). The statistical results by Stu-
dent t-test supported our hypothesis that the iodo functionality
of 2-iodochalcones has an important role in glucose uptake activity
(p value = 0.0010, 0.0002 and 0.0006 for iodo vs fluoro, hydroxy
and hydrogen, respectively). On the other hand, bromo and chloro
substitution at position 2 on A-ring showed borderline significance
(p value = 0.0392 and 0.0488 for bromo vs fluoro and hydroxy,
respectively; p value = 0.0611 for chloro vs fluoro). These data
suggest that the glucose uptake activity of chalcone is significantly
affected by iodo substitution at position 2 on A-Ring.
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C.-T. Hsieh et al. / Bioorg. Med. Chem. Lett. 22 (2012) 3912–3915
3915
19. van de Venter, M.; Roux, S.; Bungu, L. C.; Louw, J.; Crouch, N. R.; Grace, O. M.; differentiated adipocytes was changed to DMEM containing 300 mg/dl
D-
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glucose with or without the administration of tested compounds. After 24 h,
the anti-diabetic activity was determined by measuring the medium glucose
concentration using a Roche Cobas Integra 400 Chemistry Analyzer (Roche
Diagnostics, Taipei, Taiwan). The coefficient of variation (CV) of the analyzer
was 0.62–0.92% within-run and 1.1–1.2% between days. To confirm whether
our in vitro model was sufficient to measure the glucose-lowering effect,
insulin, pioglitazone and rosiglitazone maleate (RSZ) were used as positive
controls. The insulin powder was dissolved in 0.01 M acetic acid (pH 3.0) to
20. Krisanapun, C.; Lee, S. H.; Peungvicha, P.; Temsiririrkkul, R.; Baek, S. J. Evid.
Based Complement. Alternat. Med. 2011, 2011, 167684.
21. Equal amounts (5 ꢀ 105 cells) of 3T3-L1 pre-adipocytes (BCRC#60159;
Bioresource Collection and Research Center, Taiwan) were seeded and
cultured in normal D-glucose (100 mg/dl) DMEM with 10% FBS, 100 U/ml of
penicillin and 100 l g/ml of streptomycin in a humidified atmosphere of 95% air
and 5% CO2 at 37 °C. When the cell density reached 100% confluence, 3T3-L1
preadipocytes were induced to be differentiated by treating the culture with
provide
a
10ꢁ2
M
stock solution and then diluted in distilled water.
g/ l stock solutions and
Compounds were dissolved in DMSO to make 50
l
l
450 mg/dl -glucose, 0.32
D
lM insulin, 0.5 mM 3-isobutyl-1-methylxanthine
then diluted in DMSO; the final concentration of DMSO in the medium was
0.1%.
and 1 lM dexamethasone for 2 days. Then, the culture medium of the