Design, synthesis and biological evaluation of novel coumarin thiazole derivatives as α-glucosidase inhibitors

Article abstract of DOI:10.1016/j.bioorg.2016.03.001

A new series of coumarin thiazole derivatives 7a-7t were synthesized, characterized by ¹H NMR, ¹³C NMR and element analysis, evaluated for their α-glucosidase inhibitory activity. The majority of the screened compounds displayed potent inhibitory activities with IC₅₀ values in the range of 6.24 ± 0.07-81.69 ± 0.39 μM, when compared to the standard acarbose (IC₅₀ = 43.26 ± 0.19 μM). Structure-activity relationship (SAR) studies suggest that the pattern of substitution in the phenyl ring is closely related to the biological activity of this class of compounds. Among all the tested molecules, compound 7e (IC₅₀ = 6.24 ± 0.07 μM) was found to be the most active compound in the library of coumarin thiazole derivatives. Enzyme kinetic studies showed that compound 7e is a non-competitive inhibitor with a K_i of 6.86 μM. Furthermore, the binding interactions of compound 7e with the active site of α-glucosidase were confirmed through molecular docking. This study has identified a new class of potent α-glucosidase inhibitors for further investigation.

Full text of DOI:10.1016/j.bioorg.2016.03.001

Accepted Manuscript
Design, synthesis and biological evaluation of novel coumarin thiazole deriva-
tives as α-glucosidase inhibitors
Guangcheng Wang, Dianxiong He, Xin Li, Juan Li, Zhiyun Peng
PII:
S0045-2068(16)30020-7
DOI:
http://dx.doi.org/10.1016/j.bioorg.2016.03.001
YBIOO 1888
Reference:
To appear in:
Bioorganic Chemistry
Received Date:
Revised Date:
Accepted Date:
21 January 2016
29 February 2016
2 March 2016
Please cite this article as: G. Wang, D. He, X. Li, J. Li, Z. Peng, Design, synthesis and biological evaluation of novel
coumarin thiazole derivatives as α-glucosidase inhibitors, Bioorganic Chemistry (2016), doi: http://dx.doi.org/
1
0.1016/j.bioorg.2016.03.001
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Design, synthesis and biological evaluation
of novel coumarin thiazole derivatives as
α-glucosidase inhibitors
Guangcheng Wang*, Dianxiong He, Xin Li, Juan Li, Zhiyun Peng
College of Chemistry and Chemical Engineering, Jishou University, Jishou 416000,
PR China
*
Corresponding Author
Tel.: +86 743 8563911
Fax: +86 743 8563911
E-mail address: wanggch123@163.com
1

Abstract.
A new series of coumarin thiazole derivatives 7a-7t were synthesized, characterized
1
13
by H NMR, C NMR and element analysis, evaluated for their α-glucosidase
inhibitory activity. The majority of the screened compounds displayed potent
inhibitory activities with IC50 values in the range of 6.24±0.07 to 81.69±0.39 μM,
when compared to the standard acarbose (IC50 = 43.26±0.19 μM). Structure–activity
relationship (SAR) studies suggest that the pattern of substitution in the phenyl ring is
closely related to the biological activity of this class of compounds. Among all the
tested molecules, compound 7e (IC50 = 6.24±0.07 μM) was found to be the most
active compound in the library of coumarin thiazole derivatives. Enzyme kinetic
studies showed that compound 7e is a non-competitive inhibitor with a K of 6.86 μM.
i
Furthermore, the binding interactions of compound 7e with the active site of
α-glucosidase were confirmed through molecular docking. This study has identified a
new class of potent α-glucosidase inhibitors for further investigation.
Keywords: Coumarin; Thiazole; α-Glucosidase inhibitor; Enzyme kinetic study;
Molecular docking
2

1
. Introduction.
Diabetes mellitus is the most common metabolic disorder worldwide, characterized
by hyperglycemia, which is due to insulin deficiency or insulin resistance [1]. The
chronic hyperglycemia of diabetes causes serious damage to many of the body’s
organs, especially the eyes, kidneys, nerves, heart, and blood vessels [2, 3]. Therefore,
one therapeutic approach for diabetes is to reduce the abnormally high blood sugar
level and control subsequent complications.
α-Glucosidase is a membrane-bound enzyme located in the brush-border surface
membrane of intestinal cells, which catalyzes the cleavage of glucose from
disaccharides [4]. Inhibition of α-glucosidase can significantly delay the glucose
absorption and decrease postprandial blood glucose level and therefor can be an
important strategy for the treatment type-2 diabetic patients [5, 6]. In addition,
α-glucosidase inhibition is a potential strategy for development of novel anti-HIV [7,
8
] and anti-cancer agents [9]. For this reason, α-glucosidase is an attractive target for
pharmaceutical studies, and the development of new α-glucosidase inhibitors is still in
progress.
Coumarin derivatives are an important class of naturally organic compounds, which
are predominantly found in higher plants. Coumarin derivatives are of great interest
due to their diverse structural features and versatile biological properties, such as
anticancer [10], antimalarial [11], antiinflammatory [12], antioxidant [13],
antitubercular [14] and antimicrobial [15]. Over the last few years, numerous efforts
3

have been focusing on the research and development of coumarin derivatives as
potential drugs and some of them have been approved for clinic use [16, 17].
Furthermore, recent studies have shown that numbers of compounds containing the
coumarin skeleton act as α-glycosidase inhibitors (Figure 1) [18-21].
On the other hand, thiazoles and their derivatives have attracted continuing interest
over the years because of their varied biological activities such as anti-inflammatory
[
22], antiproliferative [23], anticonvulsant [24], antifungal [25] and antibacterial [26].
Recently, several substituted thiazole derivatives has been reported in the literature to
possess potent α-glucosidase inhibitory activities (Figure 1) [27, 28].
Over the years, molecular hybrid-based approaches had gained more attention by
researchers to discover some more potent α-glucosidase inhibitors [29-31], which
containing two or more bioactive pharmacophores. Based on these things mentioned
above, and in an attempt to find new potent α-glucosidase inhibitors; we designed and
synthesized a series of novel coumarin thiazole derivatives 7a-7t. The synthesized
derivatives were screened for their α-glucosidase inhibitory activity in in vitro modes.
We also describe the structure-activity relationships and mechanism of action on
α-glucosidase of this series of compounds.
Please insert Figure 1 here.
2
. Chemistry.
The synthetic pathway to achieve title compounds 7a-7t is shown in Scheme 1.
Salicylaldehyde 1 is reflux with ethyl acetoacetate in the presence of piperidine which
4

gave 3-acetyl coumarin 2. Treatment of 2 with NBS in the presence of
p-toluenesulfonic acid (TsOH) in acetonitrile to give 3-(2-bromoacetyl)-2H-chromen-
2
-one 3 in high yield [32]. Cyclization of 3 with ethyl thiooxamate in refluxing EtOH
efficiently provides ethyl 4-(2-oxo-2H-chromen- 3-yl)thiazole-2-carboxylate 4, which
reacted with hydrazine hydrate to provide the key intermediate 5. Finally, the new
desired compounds 7a-7t were obtained, in good yields (55 %-88 %), by condensing
hydrazide 5 with the corresponding appropriate aldehydes in the presence of glacial
acetic acid. The structures of newly synthesized compounds were confirmed by their
1
13
1
H NMR, C NMR and elemental analysis. In their H NMR spectra, the single peak
of CH proton of coumarin was observed at 8.69-8.74 ppm, and the single peak of CH
proton of thiazole was observed at 9.00-9.06 ppm. The resonances of aromatic
protons were observed in the range 6.78-7.86 ppm. The single peak of CH proton of
hydrazone moiety was observed at 8.56-8.95 ppm, and the signal of NH was showed
1
at 10.95-12.15 ppm. The H NMR spectra of all newly synthesized compounds (7a-7t)
1
3
showed the expected proton resonances and integration values. Moreover, in their C
NMR spectra, the number of signals equals the number of different carbons in the
molecule.
Please insert Scheme 1 here.
3
3
. Results and discussion.
.1. α-Glucosidase inhibition assay
The α-glucosidase inhibitory activities of coumarin thiazole derivatives 7a-7t were
5

evaluated according to the literature procedure with minor modification [27].
Acarbose (commercially available carbohydrate-based α-glucosidase inhibitor) was
used as positive controls in the assays. The results were summarized in Table 1. The
majority of the screened compounds displayed potent α-glucosidase inhibitory activity,
with IC50 values in the range of 6.24±0.07 to 81.69±0.39 μM, when compared to
acarbose (43.26±0.19 μM, The value of IC50 is similar to previous literature report [27,
3
3-35]). Among them, compound 7e and 7h represented the most potent
α-glucosidase inhibitory activity with IC50 values of 6.24±0.07 and 8.23±0.13 μM,
respectively.
Please insert Table 1 here.
3
.2. Structure-activity relationships summary
Based on our results, the following structure-activity relationships (SARs) of the
coumarin thiazole derivatives can be summarized. Introduction of electron
withdrawing groups such as trifluoromethyl (7o), fluorine (7g, 7p and 7q), chlorine
(
7e, 7h, 7m and 7n), and bromine (7r) into the phenyl ring, results in a significant
increase the inhibitory activity. Among them, it is interesting to point out that 7e and
h (3,5-Cl , 2-OH in 7e and 5-Cl, 2-OH in 7h) containing the hydroxyl group at
7
2
ortho-position of the phenyl ring and chlorine at the phenyl ring displayed the most
potent α-glucosidase inhibitory activity, especially with the IC50 value of 6.24±0.07
μM in 7e (Table 1). The activity of 7h (5-Cl, 2-OH) was lower than 7e (3,5-Cl
2
,
2
-OH), which indicates that the number and position of chlorine group is very
6

important for the activity. Additionally, the introduction of methoxyl group at the
phenyl ring (7a, 7f, 7l, 7s and 7t) resulted in a remarkable decrease the biological
activity, except the phenyl ring have ortho-hydroxyl group (7i). These results
indicated the pattern of substitution in the phenyl ring is closely related to the
biological activity of this class of compounds. In summary, the information of
structure-activity relationships provided us a guideline to improve α-glucosidase
inhibitory activity in the future structural modification.
3
.3. Enzyme kinetic study
To study the mechanism of action on α-glucosidase of this series of compounds, the
kinetic studies of the most active compound 7e was performed using
Lineweaver-Burk plot analysis. In the enzyme kinetic studies, the rate of the enzyme
activity was measured at four different concentrations of compound 7e using four
different concentrations of the substrate p-nitrophenyl α-D-glucopyranoside (0.25, 0.5,
1
.0, 2.0 mM). Graphical analysis of the reciprocal Lineweaver-Burk plots showed that
max of enzyme decreased without affecting the K of enzyme (Figure 2A). This
V
m
pattern indicates a non-competitive inhibition. In order to determine Ki constants of
compound 7e in the media, the secondary re-plots of Lineweaver-Burk plots were
plotted (Figure 2B). The Ki value was 6.86 μM and the point of intersection of lines
represents the value of Ki, which was drawn by using slope (obtained from
Lineweaver-Burk plot) versus inhibitor concentrations values. The results proved that
compound 7e was a non-competitive inhibitor against α-glucosidase with a K of 6.86
i
7

μM.
Please insert Figure 1 here.
3
.4. Homology model
The crystallographic structure of Saccharomyces cerevisiae α-glucosidase enzyme has
not been published yet, a number of homology models of α-glucosidase have been
reported in the literature [27, 36]. In order to expose the binding mode between the
compounds and Saccharomyces cerevisiae α-glucosidase at the molecular level, the
3
D structure of α-glucosidase was built by means of modeller 9.15 homology
modeling software (http://salilab.org/modeller/). The sequence in FASTA format of
α-glucosidase was retrieved from UniProt (access code P53341). The crystallographic
structure of Saccharomyces cerevisiae isomaltase (PDB ID: 3AJ7) with 72.4% was
selected as the template for modeling.
3
.5. Molecular docking simulation
The theoretical binding mode of 7e and Saccharomyces cerevisiae α-glucosidase was
shown in Figure 3. Compound 7e adopted a compact conformation binding at the
porket of the α-glucosidase. The 3,5-dichloro-2-hydroxyphenyl group of 7e bind at
the bottom of the α-glucosidase pocket and made a high density of vander Waals
contacts, whereas the other side of 7e was positioned near the entrance of the pocket
and made only a few contacts. Detailed analysis showed that 3,5-dichloro-
2
-hydroxyphenyl group of 7e formed arene-cation interactions with residues Arg-439
and Arg-312, respectively. Moreover, a Cl-π interaction was observed between the
8

residue Phe-300 and the 5 position of the chlorine atom atom at the phenyl ring of 7e.
In addition, the coumarin group of 7e located at the hydrophobic pocket, surrounded
by residues Phe-157, Phe-177 and Pro-240. It was shown that both Glu-276 (bond
length: 2.6 Å) and His-279 (bond length: 3.0 Å) formed hydrogen bonds with 7e,
which was the main interactions between 7e and α-glucosidase. In summary, the
above molecular simulations give us rational explanation of the interactions between
7
e and α-glucosidase, which provided valuable information for further development
of α-glucosidase inhibitors.
Please insert Figure 3 here.
4
. Conclusions.
In conclusion, we designed, synthesized and biological evaluation of a series of novel
coumarin thiazole derivatives 7a-7t. The majority of the screened compounds
displayed potent α-glucosidase inhibitory activity. Among them, compound 7e (IC50
=
6
.24±0.07 μM) was found to be the most active compound. Enzyme kinetic studies
showed that compound 7e is a non-competitive inhibitor with a K of 6.86 μM.
i
Moreover, some structure-activity relationships of coumarin thiazole derivatives were
determined and will be useful in the future to guide the design and modification of
this type of compound derivatives as α-glucosidase inhibitors. Furthermore the
docking study has predicted that compound 7e bind to the active site of the
Saccharomyces cerevisiae α-glucosidase through both hydrophobic and hydrogen
interactions. This study presented here provide a new class structure type for the
9

development of novel α-glucosidase inhibitors. In the future research we will be
exploring for a clear structure-activity relationship of this type of compound and
discovering more potent α-glucosidase inhibitors.
5
5
. Experimental section.
.1. Chemistry.
All starting materials and reagents were purchased from commercial suppliers.
Melting points were determined on an X-4 microscope melting point apparatus
(
Shanghai instrument physical optics instrument Co., LTD) and were uncorrected.
TLC was performed on 0.20 mm Silica Gel 60 F254 plates (Qingdao Ocean Chemical
Factory, Shandong, China). Nuclear magnetic resonance spectra (NMR) were
recorded at 400 MHz on a Bruker Advance II spectrometer and reported in parts per
million.) The elemental analysis was measured by an Elementary Vario EL III
analyzer.
5
.1.1. 3-Acetyl-2H-chromen-2-one (2).
A mixture of salicylaldehyde 1 (1.22 g, 10 mmol) and ethyl acetoacetate (2 g, 15
mmol) in ethanol were taken in round bottom flask. To this mixture, few drops of
piperidine were added and refluxed for 3 h. After completion of reaction, the content
was poured on crushed ice and the precipitate was collected by filtration to obtain 2
1
(
1.5 g, 79 %). H NMR (CDCl
3
, 400 MHz) δ: 2.73 (s, 3H, COCH ), 7.33-7.35 (m, 2H,
3
ArH), 7.64-7.69 (m, 2H, ArH), 8.51 (s, 1H, CH).
.1.2. 3-(2-Bromoacetyl)-2H-chromen-2-one (3).
5
10

To a solution of 2 (188 mg, 1 mmol) in CH
3
CN (10 mL) was added NBS (182 mg,
.02 mmol) and p-toluenesulfonic acid (190 mg, 1 mmol). The mixture was stirred at
0 °C for 5 h and monitored by TLC. After completion of reaction, the solvent was
1
5
removed under reduced pressure and the residue was poured into 10 % NaHCO
3
solution (50 mL). The aqueous layer was extracted with ethyl acetate, washed with
brine, dried (Na
2
SO
4
), and then concentrated in vacuo. The residue was purified by
1
silica gel column chromatography to provide 3 as a white solid in 75 % yield. H
NMR (CDCl
3
, 400 MHz) δ: 4.76 (s, 2H, COCH
.69-7.73 (m, 2H, ArH), 8.65 (s, 1H, CH).
.1.3. Ethyl 4-(2-oxo-2H-chromen-3-yl)thiazole-2-carboxylate (4).
2
Br), 7.37-7.42 (m, 2H, ArH),
7
5
A solution of 3 (267 mg, 1 mmol) and ethyl thiooxamate (133 mg, 1 mmol) in
absolute EtOH (20 mL) was stirred at 80 °C for 5 h. After the completion of the
reaction, the solvent was evaporated under reduced pressure and water was added to
the reaction mixture and extracted 3 times for ethyl acetate. The combined organic
layers were dried over Na
2
SO
4
and concentrated under vacuum. The residue was
1
purified by flash chromatography to give 190 mg (63 %) of product. H NMR (CDCl
3
,
4
1
7
5
00 MHz) δ: 1.49 (t, 3H, J = 7.2 Hz, CH
3
), 4.51 (q, 2H, J = 7.2 Hz, OCH ), 7.32 (t,
2
H, J = 8.0 Hz, ArH), 7.38 (d, 1H, J = 8.0 Hz, ArH), 7.58 (t, 1H, J = 8.0 Hz, ArH),
.66 (d, 1H, J = 8.0 Hz, ArH), 8.74 (s, 1H, CH), 8.92 (s, 1H, SCH).
.1.4. 4-(2-Oxo-2H-chromen-3-yl)thiazole-2-carbohydrazide (5).
To a solution of 4 (301 mg, 1 mmol) in ethanol (10 mL) was added hydrazine (100 mg,
11

2
mmol) and the mixture was heated to reflux for 4 hours. After cooling, the
precipitate was collected by filtration and washed with ethanol to give 5 (208 mg,
1
6
7
1
7
2 %) as a white solid. H NMR (d -DMSO, 400 MHz) δ: 4.76 (s, 2H, NH ), 7.46 (t,
2
H, J = 8.0 Hz, ArH), 7.50 (d, 1H, J = 8.0 Hz, ArH), 7.69 (t, 1H, J = 8.0 Hz, ArH),
.76 (d, 1H, J = 8.0 Hz, ArH), 8.59 (s, 1H, CH), 9.07 (s, 1H, SCH), 10.23 (s, 1H,
CONH).
.1.5.(E)-N'-(4-Methoxybenzylidene)-4-(2-oxo-2H-chromen-3-yl)thiazole-2-carbo
5
hydrazide (7a).
A mixture of 5 (287 mg, 1 mmol), Anisic aldehyde 6a (136 mg, 1 mmol) were
refluxed in ethanol for 4 h in the presence of few drops of glacial acetic acid. After the
mixture is cooled at room temperature, the product precipitated is filtered off and then
washed with petroleum ether to give 7a as a white solid (319 mg, 79 %); m.p.
o
1
6
2
8
44-246 C; H NMR (d -DMSO, 400 MHz) δ: 3.83 (s, 3H, OCH
3
), 7.05 (d, 2H, J =
.8 Hz, ArH), 7.47 (t, 1H, J = 8.0 Hz, ArH), 7.51 (d, 1H, J = 8.0 Hz, ArH), 7.69 (t, 1H,
J = 8.0 Hz, ArH), 7.72 (d, 2H, J = 8.8 Hz, ArH), 7.84 (d, 1H, J = 8.0 Hz, ArH), 8.65 (s,
1
3
1
H, NCH), 8.69 (s, 1H, CH), 9.04 (s, 1H, SCH), 12.10 (s, 1H, NH); C NMR
6
(
d -DMSO, 100 MHz) δ: 55.3 (OCH
3
), 114.4, 116.2, 119.0, 120.0, 124.9, 125.1, 126.5,
1
28.5, 129.0, 132.4, 140.5, 148.4, 150.1, 152.8, 155.2, 158.8, 161.2, 162.4; Anal.
S: C, 62.21; H, 3.73; N, 10.36; O, 15.79; S, 7.91; Found: C,
2.19; H, 3.75; N, 10.33.
.1.6.(E)-N'-(2-Hydroxybenzylidene)-4-(2-oxo-2H-chromen-3-yl)thiazole-2-carbo
Calcd for C21
H
15
N
3
O
4
6
5
12

hydrazide (7b).
The compound 7b was prepared in a similar manner to the procedure described for the
o
1
6
preparation of 7a to yield a solid (78 %); m.p. 251-252 C; H NMR (d -DMSO, 400
MHz) δ: 6.93-6.98 (m, 2H, ArH), 7.34 (t, 1H, J = 7.2 Hz, ArH), 7.46 (t, 1H, J = 8.0
Hz, ArH), 7.51 (d, 1H, J = 8.0 Hz, ArH), 7.63 (d, 1H, J = 8.0 Hz, ArH), 7.70 (t, 1H, J
=
8.0 Hz, ArH), 7.86 (d, 1H, J = 8.0 Hz, ArH), 8.71 (s, 1H, CH), 8.95 (s, 1H, NCH),
1
3
6
9
.05 (s, 1H, SCH), 10.95 (s, 1H, NH); C NMR d -DMSO, 100 MHz) δ: 116.2, 116.4,
18.9, 119.5, 120.0, 125.1, 128.8, 128.9, 131.9, 132.4, 140.5, 148.5, 149.7, 152.8,
55.3, 157.5, 158.8, 161.8; Anal. Calcd for C20 S: C, 61.37; H, 3.35; N, 10.74;
O, 16.35; S, 8.19; Found: C, 61.34; H, 3.38; N, 10.71.
.1.7.(E)-N'-(4-Hydroxybenzylidene)-4-(2-oxo-2H-chromen-3-yl)thiazole-2-carbo
1
1
H
13
N
3
O
4
5
hydrazide (7c).
The compound 7c was prepared in a similar manner to the procedure described for the
o
1
6
preparation of 7a to yield a solid (86 %); m.p. 273-275 C; H NMR (d -DMSO, 400
MHz) δ: 6.87 (d, 2H, J = 8.8 Hz, ArH), 7.46 (t, 1H, J = 8.0 Hz, ArH), 7.51 (d, 1H, J =
8
1
.0 Hz, ArH), 7.61 (d, 2H, J = 8.8 Hz, ArH), 7.70 (t, 1H, J = 8.0 Hz, ArH), 7.84 (d,
H, J = 8.0 Hz, ArH), 8.61 (s, 1H, NCH), 8.69 (s, 1H, CH), 9.05 (s, 1H, SCH), 10.22
1
3
6
(
s, 1H, NH); C NMR (d -DMSO, 100 MHz) δ: 115.8, 116.2, 119.0, 120.0, 124.8,
1
1
24.9, 125.1, 128.8, 129.2, 132.3, 140.5, 148.4, 150.5, 152.8, 155.1, 158.8, 159.8,
62.5; Anal. Calcd for C20 S: C, 61.37; H, 3.35; N, 10.74; O, 16.35; S, 8.19;
H
13
N
3
O
4
Found: C, 61.35; H, 3.37; N, 10.72.
13

5
.1.8.(E)-N'-(3,5-Di-tert-butyl-2-hydroxybenzylidene)-4-(2-oxo-2H-chromen-3-yl)
thiazole-2-carbohydrazide (7d).
The compound 7d was prepared in a similar manner to the procedure described for the
o
1
6
preparation of 7a to yield a solid (67 %); m.p. 235-237 C; H NMR (d -DMSO, 400
MHz) δ: 1.31 (s, 9H, CH ), 1.43 (s, 9H, CH ), 7.24 (d, 1H, J = 2.0 Hz, ArH), 7.36 (d,
H, J = 2.0 Hz, ArH), 7.47 (t, 1H, J = 8.0 Hz, ArH), 7.52 (d, 1H, J = 8.0 Hz, ArH),
.71 (t, 1H, J = 8.0 Hz, ArH), 7.84 (d, 1H, J = 8.0 Hz, ArH), 8.74 (s, 1H, CH), 8.86 (s,
3
3
1
7
1
1
3
H, NCH), 9.02 (s, 1H, SCH), 12.03 (s, 1H, NH), 12.61 (s, 1H, OH); C NMR
6
(
d -DMSO, 100 MHz) δ: 29.3 (CH
3
), 31.2 (CH
3
), 33.9 (-C-CH
3
), 34.7 (-C-CH ),
3
116.2, 116.8, 118.9, 120.0, 125.1, 125.4, 126.0, 126.2, 128.7, 132.5, 135.9, 140.5,
1
40.6, 148.6, 152.8, 153.7, 154.9, 155.2, 158.8, 161.5; Anal. Calcd for C28
H
29
N
3
4
O S:
C, 66.78; H, 5.80; N, 8.34; O, 12.71; S, 6.37; Found: C, 66.75; H, 5.83; N, 8.35.
.1.9.(E)-N'-(3,5-Dichloro-2-hydroxybenzylidene)-4-(2-oxo-2H-chromen-3-yl)thia
5
zole-2-carbohydrazide (7e).
The compound 7e was prepared in a similar manner to the procedure described for the
o
1
6
preparation of 7a to yield a solid (76 %); m.p. 285-288 C; H NMR (d -DMSO, 400
MHz) δ: 7.44 (t, 1H, J = 8.0 Hz, ArH), 7.50 (d, 1H, J = 8.0 Hz, ArH), 7.59 (s, 2H,
ArH), 7.69 (t, 1H, J = 8.0 Hz, ArH), 7.88 (d, 1H, J = 8.0 Hz, ArH), 8.69 (s, 1H, CH),
1
3
6
8
.84 (s, 1H, NCH), 9.00 (s, 1H, SCH), 12.05 (s, 1H, NH); C NMR (d -DMSO, 100
MHz) δ: 116.2, 118.9, 119.9, 121.0, 122.0, 125.1, 128.0, 128.9, 130.6, 132.4, 140.5,
-
1
48.6, 148.7, 152.8, 156.1, 158.8, 160.9; MS (ESI, m/z): 458.02 [M-H] ; Anal. Calcd
14

for C20
H
11Cl
2
N
3
O
4
S: C, 52.19; H, 2.41; Cl, 15.40; N, 9.13; O, 13.90; S, 6.97; Found:
C, 52.15; H, 2.44; N, 9.10.
.1.10.(E)-N'-(3-Hydroxy-4-methoxybenzylidene)-4-(2-oxo-2H-chromen-3-yl)thia
5
zole-2-carbohydrazide (7f).
The compound 7f was prepared in a similar manner to the procedure described for the
o
1
preparation of 7a to yield a solid (55 %); m.p. 218-219 C; H NMR (CDCl
3
, 400
MHz) δ: 3.83 (s, 3H, OCH ), 7.01 (d, 1H, J = 8.0 Hz, ArH), 7.11 (dd, 1H, J = 8.0 Hz,
3
2
1
8
1
1
1
.0 Hz, ArH), 7.32 (d, 1H, J = 2.0 Hz, ArH), 7.47 (t, 1H, J = 8.0 Hz, ArH), 7.51 (d,
H, J = 8.0 Hz, ArH), 7.69 (t, 1H, J = 8.0 Hz, ArH), 7.85 (d, 1H, J = 8.0 Hz, ArH),
.56 (s, 1H, NCH), 8.69 (s, 1H, CH), 9.05 (s, 1H, SCH), 9.37 (s, 1H, OH), 12.06 (s,
1
3
6
H, NH); C NMR (d -DMSO, 100 MHz) δ: 55.6 (OCH
20.0, 120.7, 124.9, 125.1, 126.7, 128.8, 132.4, 140.5, 147.0, 148.4, 150.2, 150.4,
52.8, 155.2, 158.8, 162.4; Anal. Calcd for C21 S: C, 59.85; H, 3.59; N, 9.97;
3
), 111.9, 112.4, 116.2, 119.0,
H
15
N
3
O
5
O, 18.98; S, 7.61; Found: C, 59.82; H, 3.63; N, 9.93.
.1.11.(E)-N'-(3-Fluoro-4-hydroxybenzylidene)-4-(2-oxo-2H-chromen-3-yl)thiazol
5
e-2-carbohydrazide (7g).
The compound 7g was prepared in a similar manner to the procedure described for the
o
1
preparation of 7a to yield a solid (83 %); m.p. 225-226 C; H NMR (CDCl
3
, 400
MHz) δ: 7.06 (t, 1H, J = 8.0 Hz, ArH), 7.41 (d, 1H, J = 8.0 Hz, ArH), 7.46 (t, 1H, J =
8
8
.0 Hz, ArH), 7.51-7.55 (m, 2H, ArH), 7.70 (t, 1H, J = 8.0 Hz, ArH), 7.85 (d, 1H, J =
.0 Hz, ArH), 8.60 (s, 1H, NCH), 8.69 (s, 1H, CH), 9.04 (s, 1H, SCH), 10.49 (s, 1H,
15

1
3
6
OH), 12. 15 (s, 1H, NH); C NMR (d -DMSO, 100 MHz) δ: 114.1, 114.3, 116.2,
18.0, 119.0, 120.0, 124.8, 125.0, 125.1, 125.7, 128.8, 132.4, 140.5, 147.4, 148.5,
49.4, 152.8, 155.3, 158.8, 162.3; Anal. Calcd for C20 S: C, 58.68; H, 2.95; F,
1
1
4
5
H
12FN
3
O
4
.64; N, 10.26; O, 15.63; S, 7.83; Found: C, 58.69; H, 2.97; N, 10.23.
.1.12.(E)-N'-(5-Chloro-2-hydroxybenzylidene)-4-(2-oxo-2H-chromen-3-yl)thiazo
le-2-carbohydrazide (7h).
The compound 7h was prepared in a similar manner to the procedure described for the
o
1
preparation of 7a to yield a solid (79 %); m.p. 285-286 C; H NMR (CDCl
3
, 400
MHz) δ: 6.96 (d, 1H, J = 8.8 Hz, ArH), 7.33 (dd, 1H, J = 8.8 Hz, 2.0 Hz, ArH), 7.46 (t,
1
1
H, J = 8.0 Hz, ArH), 7.51 (d, 1H, J = 8.0 Hz, ArH), 7.68-7.72 (m, 2H, ArH), 7.86 (d,
H, J = 8.0 Hz, ArH), 8.71 (s, 1H, CH), 8.91 (s, 1H, NCH), 9.04 (s, 1H, SCH), 10.92
1
3
6
(
s, 1H, NH); C NMR (d -DMSO, 100 MHz) δ: 116.2, 118.3, 118.9, 120.0, 120.9,
1
1
23.1, 125.1, 125.2, 126.8, 128.8, 131.2, 132.4, 140.5, 147.1, 148.6, 152.8, 155.5,
-
56.0, 158.8, 161.7; MS (ESI, m/z): 424.03 [M-H] ; Anal. Calcd for C20
H12ClN
3
4
O S:
C, 56.41; H, 2.84; Cl, 8.33; N, 9.87; O, 15.03; S, 7.53; Found: C, 56.40; H, 2.82; N,
9
.85.
5
.1.13.(E)-N'-(2-Hydroxy-4-methoxybenzylidene)-4-(2-oxo-2H-chromen-3-yl)thia
zole-2-carbohydrazide (7i).
The compound 7i was prepared in a similar manner to the procedure described for the
o
1
preparation of 7a to yield a solid (66 %); m.p. 222-224 C; H NMR (CDCl
3
, 400
MHz) δ: 3.79 (s, 3H, OCH ), 6.51 (d, 1H, J = 2.0 Hz, ArH), 6.54 (dd, 1H, J = 8.0 Hz,
3
16

2
8
9
.0 Hz, ArH), 7.46 (t, 1H, J = 8.0 Hz, ArH), 7.49-7.53 (m, 2H, ArH), 7.70 (t, 1H, J =
.0 Hz, ArH), 7.85 (d, 1H, J = 8.0 Hz, ArH), 8.69 (s, 1H, CH), 8.83 (s, 1H, NCH),
1
3
6
.03 (s, 1H, SCH), 11.10 (s, 1H, NH); C NMR (d -DMSO, 100 MHz) δ: 55.3
), 101.1, 106.6, 111.9, 116.2, 118.9, 120.0, 125.0, 125.1, 128.8, 130.7, 132.4,
40.5, 148.5, 150.3, 152.8, 155.2, 158.8, 159.5, 162.1, 162.4; Anal. Calcd for
S: C, 59.85; H, 3.59; N, 9.97; O, 18.98; S, 7.61; Found: C, 59.82; H, 3.53;
(
OCH
3
1
C
21
H
15
N
3
O
5
N, 9.94.
.1.14.(E)-N'-(2,4-Dihydroxybenzylidene)-4-(2-oxo-2H-chromen-3-yl)thiazole-2-c
5
arbohydrazide (7j).
The compound 7j was prepared in a similar manner to the procedure described for the
o
1
preparation of 7a to yield a solid (81 %); m.p. 276-278 C; H NMR (CDCl
3
, 400
MHz) δ: 6.78 (s, 2H, ArH), 7.08 (s, 1H, ArH), 7.46 (t, 1H, J = 8.0 Hz, ArH), 7.51 (d,
1
8
1
1
1
7
5
H, J = 8.0 Hz, ArH), 7.70 (t, 1H, J = 8.0 Hz, ArH), 7.86 (d, 1H, J = 8.0 Hz, ArH),
.70 (s, 1H, CH), 8.87 (s, 1H, NCH), 9.06 (s, 1H, SCH), 10.25 (s, 1H, OH), 10.81 (s,
1
3
6
H, NH); C NMR (d -DMSO, 100 MHz) δ: 113.0, 116.2, 117.2, 119.0, 119.2, 119.4,
20.0, 125.0, 125.1, 128.8, 132.4, 140.5, 148.5, 149.0, 149.9, 150.3, 152.8, 155.4,
58.8, 162.1; Anal. Calcd for C20
.87; Found: C, 58.93; H, 3.26; N, 10.28.
.1.15.(E)-N'-(3,4-Dihydroxybenzylidene)-4-(2-oxo-2H-chromen-3-yl)thiazole-2-c
H
13
N
3
5
O S: C, 58.96; H, 3.22; N, 10.31; O, 19.64; S,
arbohydrazide (7k).
The compound 7k was prepared in a similar manner to the procedure described for the
17

o
1
preparation of 7a to yield a solid (77 %); m.p. 205-208 C; H NMR (CDCl , 400
3
MHz) δ: 6.82 (d, 1H, J = 8.8 Hz, ArH), 6.99 (d, 1H, J = 8.8 Hz, ArH), 7.30 (s, 1H,
ArH), 7.46 (t, 1H, J = 8.0 Hz, ArH), 7.51 (d, 1H, J = 8.0 Hz, ArH), 7.70 (t, 1H, J = 8.0
Hz, ArH), 7.85 (d, 1H, J = 8.0 Hz, ArH), 8.52 (s, 1H, NCH), 8.69 (s, 1H, CH), 9.05 (s,
1
3
6
1
H, SCH), 9.81 (s, 1H, NH); C NMR (d -DMSO, 100 MHz) δ: 112.8, 115.6, 116.2,
19.0, 120.0, 121.0, 124.8, 125.1, 125.3, 128.8, 132.4, 140.5, 145.8, 148.4, 148.5,
50.7, 152.8, 155.1, 158.8, 162.5; Anal. Calcd for C20 S: C, 58.96; H, 3.22; N,
0.31; O, 19.64; S, 7.87; Found: C, 58.94; H,3.24 ; N, 10.28.
.1.16.(E)-N'-(4-Hydroxy-3,5-dimethoxybenzylidene)-4-(2-oxo-2H-chromen-3-yl)
1
1
1
5
H
13
N
3
O
5
thiazole-2-carbohydrazide (7l).
The compound 7l was prepared in a similar manner to the procedure described for the
o
1
preparation of 7a to yield a solid (59 %); m.p. 261-262 C; H NMR (CDCl
MHz) δ: 3.85 (s, 6H, OCH ), 7.03 (s, 2H, ArH), 7.47 (t, 1H, J = 8.0 Hz, ArH), 7.51 (d,
H, J = 8.0 Hz, ArH), 7.70 (t, 1H, J = 8.0 Hz, ArH), 7.83 (d, 1H, J = 8.0 Hz, ArH),
3
, 400
3
1
8
1
3
.59 (s, 1H, NCH), 8.69 (s, 1H, CH), 9.05 (s, 1H, SCH), 10.08 (s, 1H, NH); C NMR
6
(
d -DMSO, 100 MHz) δ: 56.0 (OCH
3
), 104.9, 116.2, 119.0, 120.0, 124.1, 124.9, 125.1,
1
28.7, 132.4, 138.4, 140.5, 148.2, 148.4, 150.9, 152.8, 155.2, 158.8, 162.4; Anal.
S: C, 58.53; H, 3.80; N, 9.31; O, 21.26; S, 7.10; Found: C,
8.51; H, 3.75; N, 9.30.
.1.17.(E)-N'-(4-Chlorobenzylidene)-4-(2-oxo-2H-chromen-3-yl)thiazole-2-carboh
Calcd for C22
H
17
N
3
O
6
5
5
ydrazide (7m).
18

The compound 7m was prepared in a similar manner to the procedure described for
o
1
the preparation of 7a to yield a solid (88 %); m.p. 282-284 C; H NMR (CDCl
3
, 400
MHz) δ: 7.46 (t, 1H, J = 8.0 Hz, ArH), 7.51 (d, 1H, J = 8.0 Hz, ArH), 7.55 (d, 2H, J =
8
1
.8 Hz, ArH), 7.70 (t, 1H, J = 8.0 Hz, ArH), 7.79 (d, 2H, J = 8.8 Hz, ArH), 7.85 (d,
H, J = 8.0 Hz, ArH), 8.71 (s, 2H, CH, NCH), 9.04 (s, 1H, SCH), 11.05 (s, 1H, NH);
1
3
6
C NMR (d -DMSO, 100 MHz) δ: 116.2, 118.9, 120.0, 125.1, 125.2, 128.8, 128.9,
1
29.0, 132.4, 132.9, 135.0, 140.5, 148.5, 148.9, 152.8, 155.5, 158.8, 162.1; MS (ESI,
-
m/z): 408.03 [M-H] ; Anal. Calcd for C20
H12ClN
3
3
O S: C, 58.61; H, 2.95; Cl, 8.65; N,
1
0.25; O, 11.71; S, 7.82; Found: C, 58.63; H, 2.99; N, 10.21.
.1.18.(E)-N'-(3-Chlorobenzylidene)-4-(2-oxo-2H-chromen-3-yl)thiazole-2-carboh
5
ydrazide (7n).
The compound 7n was prepared in a similar manner to the procedure described for the
o
1
preparation of 7a to yield a solid (70 %); m.p. 235-238 C; H NMR (CDCl , 400
3
MHz) δ: 7.45 (t, 1H, J = 8.0 Hz, ArH), 7.50-7.55 (m, 3H, ArH), 7.68-7.73 (m, 2H,
ArH), 7.80 (s, 1H, ArH), 7.86 (d, 1H, J = 8.0 Hz, ArH), 8.71 (s, 2H, CH, NCH), 9.05
13
6
(
s, 1H, SCH), 11.12 (s, 1H, NH); C NMR (d -DMSO, 100 MHz) δ: 116.2, 118.9,
19.9, 125.1, 125.2, 126.1, 126.4, 128.8, 130.1, 130.8, 132.4, 133.7, 136.2, 140.5,
48.5, 152.8, 155.7, 158.8, 162.0; Anal. Calcd for C20 S: C, 58.61; H, 2.95;
Cl, 8.65; N, 10.25; O, 11.71; S, 7.82; Found: C, 58.56; H, 3.01; N, 10.21.
.1.19.(E)-4-(2-Oxo-2H-chromen-3-yl)-N'-(4-(trifluoromethyl)benzylidene)thiazol
e-2-carbohydrazide (7o).
1
1
H12ClN
3
O
3
5
19

The compound 7o was prepared in a similar manner to the procedure described for the
o
1
preparation of 7a to yield a solid (64 %); m.p. 243-245 C; H NMR (CDCl
MHz) δ: 7.46 (t, 1H, J = 8.0 Hz, ArH), 7.51 (d, 1H, J = 8.0 Hz, ArH), 7.70 (t, 1H, J =
.0 Hz, ArH), 7.84-7.86 (m, 3H, ArH), 7.78 (d, 2H, J = 8.8 Hz, ArH), 8.72 (s, 1H,
3
, 400
8
13
6
CH), 8.80 (s, 1H, NCH), 9.04 (s, 1H, SCH), 11.47 (s, 1H, NH); C NMR (d -DMSO,
1
00 MHz) δ: 116.2, 118.9, 120.0, 122.7, 125.1, 125.3, 125.8, 127.9, 127.9, 128.8,
1
32.4, 137.9, 140.5, 141.0, 148.4, 148.5, 152.1, 152.8, 155.7, 158.8, 162.0; Anal.
Calcd for C21
Found: C, 56.83; H, 2.77; N, 9.45.
.1.20.(E)-N'-(2-Fluorobenzylidene)-4-(2-oxo-2H-chromen-3-yl)thiazole-2-carboh
H
12
F
3
N
3
3
O S: C, 56.88; H, 2.73; F, 12.85; N, 9.48; O, 10.83; S, 7.23;
5
ydrazide (7p).
The compound 7p was prepared in a similar manner to the procedure described for the
o
1
preparation of 7a to yield a solid (72 %); m.p. 293-296 C; H NMR (CDCl , 400
3
MHz) δ: 7.46-7.54 (m, 4H, ArH), 7.57 (d, 1H, J = 8.0 Hz, ArH), 7.71 (t, 1H, J = 8.0
Hz, ArH), 7.88 (d, 1H, J = 8.0 Hz, ArH), 8.06 (d, 1H, J = 8.0 Hz, ArH), 8.73 (s, 1H,
1
3
6
CH), 9.05 (s, 1H, SCH), 9.13 (s, 1H, NCH), 12.54 (s, 1H, NH); C NMR (d -DMSO,
1
00 MHz) δ: 116.2, 118.9, 120.0, 125.1, 125.3, 127.1, 127.7, 128.9, 130.0, 131.4,
1
31.9, 132.4, 133.5, 140.5, 146.0, 148.6, 152.8, 155.7, 158.8, 162.0; Anal. Calcd for
C
20
H12FN
3
3
O S: C, 61.06; H, 3.07; F, 4.83; N, 10.68; O, 12.20; S, 8.15; Found: C,
6
1.02; H, 3.10; N, 10.65.
5
.1.21.(E)-N'-(3-Fluorobenzylidene)-4-(2-oxo-2H-chromen-3-yl)thiazole-2-carboh
20

ydrazide (7q).
The compound 7q was prepared in a similar manner to the procedure described for the
o
1
preparation of 7a to yield a solid (85 %); m.p. 254-255 C; H NMR (CDCl
MHz) δ: 7.33 (t, 1H, J = 8.0 Hz, ArH), 7.46 (t, 1H, J = 8.0 Hz, ArH), 7.50-7.58 (m,
H, ArH), 7.61 (d, 1H, J = 8.0 Hz, ArH), 7.70 (t, 1H, J = 8.0 Hz, ArH), 7.85 (d, 1H, J
8.0 Hz, ArH), 8.71 (s, 1H, CH), 8.72 (s, 1H, NCH), 9.04 (s, 1H, SCH), 12.00 (s, 1H,
3
, 400
3
=
1
3
6
NH); C NMR (d -DMSO, 100 MHz) δ: 113.3, 116.2, 118.9, 119.9, 123.7, 125.1,
1
1
1
5
25.2, 128.8, 131.0, 132.4, 136.5, 140.5, 148.5, 148.8, 152.8, 155.6, 158.8, 161.2,
62.0, 163.6; Anal. Calcd for C20 S: C, 61.06; H, 3.07; F, 4.83; N, 10.68; O,
H12FN
3
O
3
2.20; S, 8.15; Found: C, 61.08; H, 3.10; N, 10.63.
.1.22.(E)-N'-(3-bromobenzylidene)-4-(2-oxo-2H-chromen-3-yl)thiazole-2-carboh
ydrazide (7r).
The compound 7r was prepared in a similar manner to the procedure described for the
o
1
preparation of 7a to yield a solid (80 %); m.p. 233-234 C; H NMR (CDCl , 400
3
MHz) δ: 7.44-7.48 (m, 2H, ArH), 7.50 (d, 1H, J = 8.0 Hz, ArH), 7.66-7.70 (m, 2H,
ArH), 7.76 (d, 1H, J = 8.0 Hz, ArH), 7.84 (d, 1H, J = 8.0 Hz, ArH), 7.95 (s, 1H, ArH),
1
3
8
.68 (s, 1H, CH), 8.71 (s, 1H, NCH), 9.03 (s, 1H, SCH), 11.23 (s, 1H, NH); C NMR
6
(
d -DMSO, 100 MHz) δ: 116.2, 118.9, 119.9, 122.2, 125.1, 125.2, 126.5, 128.8, 129.3,
1
31.1, 132.4, 133.0, 136.4, 140.5, 148.4, 148.5, 152.8, 155.6, 158.8, 162.0; Anal.
Calcd for C20 S: C, 52.88; H, 2.66; Br, 17.59; N, 9.25; O, 10.57; S, 7.06;
Found: C, 52.85; H, 2.64; N, 9.23.
H12BrN
3
O
3
21

5
.1.23.(E)-N'-(2-Methoxybenzylidene)-4-(2-oxo-2H-chromen-3-yl)thiazole-2-carb
ohydrazide (7s).
The compound 7s was prepared in a similar manner to the procedure described for the
o
1
preparation of 7a to yield a solid (75 %); m.p. 234-235 C; H NMR (CDCl
3
, 400
MHz) δ: 3.92 (s, 3H, OCH ), 7.06 (t, 1H, J = 8.0 Hz, ArH), 7.14 (d, 1H, J = 8.0 Hz,
3
ArH), 7.45-7.49 (m, 2H, ArH), 7.51 (d, 1H, J = 8.0 Hz, ArH), 7.71 (t, 1H, J = 8.0 Hz,
ArH), 7.87 (d, 1H, J = 8.0 Hz, ArH), 7.91 (d, 1H, J = 8.0 Hz, ArH), 8.70 (s, 1H, CH),
1
3
6
9
.06 (s, 1H, SCH), 9.08 (s, 1H, NCH), 11.35 (s, 1H, NH); C NMR (d -DMSO, 100
MHz) δ: 55.5 (OCH ), 116.2, 116.4, 118.9, 119.0, 119.5, 120.0, 125.1, 125.2, 128.8,
28.9, 131.9, 132.4, 140.6, 148.5, 149.7, 152.8, 155.3, 157.5, 158.8, 161.8; Anal.
Calcd for C21 S: C, 62.21; H, 3.73; N, 10.36; O, 15.79; S, 7.91; Found: C,
2.19; H, 3.77; N, 10.33.
3
1
H
15
N
3
O
4
6
5
2
.1.24.(E)-4-(2-Oxo-2H-chromen-3-yl)-N'-(3,4,5-trimethoxybenzylidene)thiazole-
-carbohydrazide (7t).
The compound 7t was prepared in a similar manner to the procedure described for the
o
1
preparation of 7a to yield a solid (69 %); m.p. 235-237 C; H NMR (CDCl
3
, 400
MHz) δ: 3.73 (s, 3H, OCH ), 3.86 (s, 6H, OCH ), 7.05 (s, 2H, ArH), 7.46 (t, 1H, J =
3
3
8
1
.0 Hz, ArH), 7.51 (d, 1H, J = 8.0 Hz, ArH), 7.70 (t, 1H, J = 8.0 Hz, ArH), 7.83 (d,
H, J = 8.0 Hz, ArH), 8.64 (s, 1H, NCH), 8.69 (s, 1H, CH), 9.05 (s, 1H, SCH), 10.46
1
3
6
(
s, 1H, NH); C NMR (d -DMSO, 100 MHz) δ: 55.3 (OCH
3
), 55.6 (OCH ), 115.8,
3
116.2, 119.0, 120.0, 124.8, 124.9, 125.1, 128.8, 129.2, 132.4, 140.5, 148.4, 150.5,
22

1
9
5
52.8, 155.1, 158.8, 159.8, 162.5; Anal. Calcd for C23
H
19
N
3
6
O S: C, 59.35; H, 4.11; N,
.03; O, 20.62; S, 6.89; Found: C, 59.33; H, 4.15; N, 9.01.
.2. Biological evaluation
α-Glucosidase
from
Saccharomyces
cerevisiae
and
p-nitrophenyl
α-D-glucopyranoside (pNPG) were purchased from Sigma Aldrich Chemical
Company.
5
.2.1. In vitro assay of α-glucosidase inhibitory activity
The test compounds were dissolved in DMSO to prepare the required distributing
concentration. α-Glucosidase inhibitory activity was assayed by using 50 mM
o
phosphate buffer (pH 6.8) at 37 C. The enzymatic reaction mixture composed of 20
μL α-glucosidase (0.2 U), 10 μL of various concentrations of test compounds and 140
μL of phosphate buffer was incubated at 37 °C for 10 min. Then 0.5 mM
p-nitrophenyl α-D-glucopyranoside (30 μL) was added to the mixture as a substrate.
o
After further incubation at 37 C for 30 min. The absorbance was measured
spectrophotometrically at 405 nm. The sample solution was replaced by DMSO as a
control. Acarbose was used as a positive control. All experiments were carried out in
triplicates.
The % inhibition has been obtained using the formula:
Inhibition (%) = (1-∆Asample/∆Acontrol) * 100 %
IC50 value is defined as a concentration of samples inhibiting 50 % of α-glucosidase
activity under the stated assay conditions.
23

5
.3. Molecular docking
Molecular docking studies were performed to investigate the binding mode of the
compound 7e to α-glucosidase using Autodock vina 1.1.2 (http://vina.scripps.edu).
The 3D structure of 7e was obtained by ChemBioDraw Ultra 14.0 and ChemBio3D
Ultra 14.0 softwares. The AutoDockTools 1.5.6 package (http://mgltools.scripps.edu)
was employed to generate the docking input files. The search grid of α-glucosidase
was identified as center_x: -19.676, center_y: -7.243, and center_z: -21.469 with
dimensions size_x: 15, size_y: 15, and size_z: 15. The value of exhaustiveness was
set to 20. For Vina docking, the default parameters were used if it was not mentioned.
The best-scoring pose as judged by the Vina docking score was chosen and visually
analyzed using PyMOL 1.7.6 software (http://www.pymol.org/).
Acknowledgments
This work was supported by Hunan Provincial Natural Science Foundation of China
(
(
2015JJ3099), Scientific Research Fund of Hunan Provincial Education Department
[2015]194).
References
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1] A.E. Kitabchi, G.E. Umpierrez, J.M. Miles, J.N. Fisher, Diabetes Care 32 (2009)
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1
[
[
2] A. Lopez-Candales, Journal of Medicine (Westbury) 32 (2001) 283-300.
3] A.D. Deshpande, M. Harris-Hayes, M. Schootman, Phys. Ther. 88 (2008)
1
254-1264.
24

[
[
[
[
4] A.J. Hirsh, S.Y.M. Yao, J.D. Young, C.I. Cheeseman, Gastroenterology 113 (1997)
05-211.
2
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Scheme Captions
Scheme 1. Reagents and conditions: (a) piperidine, ethanol, reflux, 3 h; (b) NBS,
p-toluenesulfonic acid, CH CN, 50 °C, 5 h; (c) ethanol, 80 °C, 5 h; (d) hydrazine,
3
ethanol, reflux, 4 h; (e) AcOH, ethanol, reflux, 4 h.
Figure Captions
Figure 1. Chemical structures of some α-glucosidase inhibitors containing coumarin
or thiazole moieties.
Figure 2. (A) Lineweaver-Burke plot of the inhibition kinetics of α-glucosidase by 7e.
(
B) Secondary re-plot of Lineweaver-Burk plot between the slopes of each line on
Lineweaver-Burk plot vs various concentrations of 7e.
Figure 3. Compound 7e was docked to the binding pocket of the Saccharomyces
cerevisiae α-glucosidase.
28

Table Captions
Table 1. α-Glucosidase inhibitory activities of coumarin thiazole derivatives.
29