1,2-Benzisoxazole-3-acetamide derivatives as dual agents for DPP-IV inhibition and anticancer activity

Article abstract of DOI:10.1080/00397911.2018.1508723

Herein, we have designed various benzisoxazole acetamide derivatives with and without glycine spacer as DPP-IV inhibitors. Compounds 9a–d and 11a–e were synthesized and screened for their in vitro DPP-IV inhibition. Compounds 11a and 11c showed moderate activity for DPP-IV inhibition, whereas other remained inactive at 25–200 μM concentrations. DPP-IV inhibition can be a good strategy for modulating diabetes and cancer; hence, we have screened compounds 9a–d and 11a–e for their anticancer activity using MTT assay against A549 and MCF7 cell lines. Compounds 9a–d without glycine spacer have shown good anticancer activity compared to compounds 11a–e with glycine spacer. Compound 9b has shown moderate activity with IC₅₀ values 4.72 ± 0.72 and 4.39 ± 0.809 μM against A549 and MCF7 cell lines, respectively. Interestingly, compound 9c with cyano group has shown very good anticancer activity with IC₅₀ 2.36 ± 0.34 μM against MCF7 cell line as compared to fluorouracil with IC₅₀ 45.04 ± 1.02 μM.

Full text of DOI:10.1080/00397911.2018.1508723

Synthetic Communications
An International Journal for Rapid Communication of Synthetic Organic
Chemistry
ISSN: 0039-7911 (Print) 1532-2432 (Online) Journal homepage: http://www.tandfonline.com/loi/lsyc20
1,2-Benzisoxazole-3-acetamide derivatives as dual
agents for DPP-IV inhibition and anticancer activity
Shubhendu Karandikar, Rina Soni, Shubhangi S. Soman, Shweta Umar &
Balakrishnan Suresh
To cite this article: Shubhendu Karandikar, Rina Soni, Shubhangi S. Soman, Shweta
Umar & Balakrishnan Suresh (2018): 1,2-Benzisoxazole-3-acetamide derivatives as dual
agents for DPP-IV inhibition and anticancer activity, Synthetic Communications, DOI:
10.1080/00397911.2018.1508723
To link to this article: https://doi.org/10.1080/00397911.2018.1508723
View supplementary material
Published online: 30 Oct 2018.
Submit your article to this journal
View Crossmark data
Full Terms & Conditions of access and use can be found at
http://www.tandfonline.com/action/journalInformation?journalCode=lsyc20

R
SYNTHETIC COMMUNICATIONSV
https://doi.org/10.1080/00397911.2018.1508723
1,2-Benzisoxazole-3-acetamide derivatives as dual agents
for DPP-IV inhibition and anticancer activity
Shubhendu Karandikara, Rina Sonia, Shubhangi S. Somana, Shweta Umarb, and
Balakrishnan Sureshb
b
aDepartment of Chemistry, The M. S. University of Baroda, Vadodara, India; Department of Zoology
Faculty of Science, The M. S. University of Baroda, Vadodara, India
ABSTRACT
ARTICLE HISTORY
Received 14 June 2018
Herein, we have designed various benzisoxazole acetamide deriva-
tives with and without glycine spacer as DPP-IV inhibitors.
Compounds 9a–d and 11a–e were synthesized and screened for
their in vitro DPP-IV inhibition. Compounds 11a and 11c showed
moderate activity for DPP-IV inhibition, whereas other remained
inactive at 25–200mM concentrations. DPP-IV inhibition can be a
good strategy for modulating diabetes and cancer; hence, we have
screened compounds 9a–d and 11a–e for their anticancer activity
using MTT assay against A549 and MCF7 cell lines. Compounds 9a–d
without glycine spacer have shown good anticancer activity com-
pared to compounds 11a–e with glycine spacer. Compound 9b has
shown moderate activity with IC50 values 4.72 0.72 and
4.39 0.809mM against A549 and MCF7 cell lines, respectively.
Interestingly, compound 9c with cyano group has shown very good
anticancer activity with IC50 2.36 0.34 mM against MCF7 cell line as
compared to fluorouracil with IC50 45.04 1.02 mM.
KEYWORDS
1,2-benzisoxazole deriva-
tives; antidiabetic activity;
DPP-IV inhibition;
anticancer activity
GRAPHICAL ABSTRACT
Introduction
DPP-IV inhibition has immerged as quite promising target to treat Type 2 diabetes.[1]
DPP-IV, a membrane-bound enzyme is expressed ubiquitously in various parts of body
like liver, intestine, spleen, adrenal gland, placenta, kidney, lymphocytes, and endothelial
cells.[2,3] This enzyme is responsible for various physiological activities like protein
CONTACT Shubhangi S. Soman
shubhangiss@rediffmail.com; Rina Soni
src_rina@outlook.com
Department of
Chemistry, The M. S. University of Baroda, Vadodara, 390002, India.
Supplemental data (full experimental detail, 1H-NMR, 13C-NMR, ESI-MS, and IR spectra) can be accessed on the
publisher’s website.
ß 2018 Taylor & Francis Group, LLC

2
S. KARANDIKAR ET AL.
turnover, regulation of inflammation, cell migration, signal transduction, tissue remodel-
ing, tumor invasion including cell adhesion, immunological response, apoptosis, and
regulating blood sugar level.[4–7] Different classes of DPP-IV have been reported and
marketed to treat Type 2 Diabetes such as Vildagliptin, Sitagliptin, Omarigliptin, etc.[8,9]
Inhibition of DPP-IV leads to increased half-life of endogenous incretins such as GLP-
1, as active sites of enzyme which cleaves the N-terminal dipeptide with L-proline and
L-alanine are blocked by inhibitors.[10]
Dang and Morimoto have reported correlation between various types of human
malignancies and DPP-IV expression levels.[11] DPP-IV enzyme has multiple functions
in the immune response and abnormal responses are observed in autoimmune disor-
ders.[12] Morimoto et al. have shown that DPP-IV enhances tumor immunity by modi-
fying chemokines and cytokines which play key roles in signaling and tumor
microenvironment.[13] These studies show that DPP-IV plays an important role in con-
trolling two life-threatening diseases like type 2-diabetes and cancer.
Benzisoxazoles are interesting scaffolds in drug discovery due to their unique binding
properties and selectivity for different biological targets. Benzisoxazole based com-
pounds have shown a wide range of biological activities such as anti-HIV, antimicrobial,
anticonvulsant, anticancer, antioxidant, and anti-diabetic.[14–19]
Rangappa et al. have reported benzisoxazole compound with modification at third
position and screened for their anticancer activity. Benzisoxazole derivative 1 showed
37.75% inhibitory activity against HepG-2 cells (Figure 1).[20] Recently, same author has
reported series of benzisoxazole with tethered triazole ring for potential anticancer activ-
ity against human acute myeloid leukemia by inhibiting Histone deacetylase enzyme
(HDAC).[21] Compound 2 showed very good anticancer activity with IC50 2.0 mM
against MV4-11 cell line using MTT assay (Figure 1).
DPP-IV cleaves N-terminal proline/alanine residues of peptides in its course of
action. For a substrate-like DPP-IV inhibitor, proline derivatives interact with S1
(hydrophilic) pocket of enzyme, whereas hydrophobic part connected by glycine inter-
acts with S2 pocket.[22] Thus, our design of substrate-like DPP-IV inhibitor has benzi-
soxazole ring as a hydrophobic part linked to nitrogen-containing groups as a
hydrophilic part with/without glycine spacer (Figure 2).
Previous studies from our laboratory have focused on synthesis and biological evalua-
tions of derivatives having isoxazole ring such as furobenzisoxazoles[23] and napthoisox-
azoles.[24] Napthoisoxazole derivative 3 showed good anticancer activity against different
melanoma cell lines, as well as good anticonvulsant activity as compared to the com-
mercial drug phenytoin. In this study, we aim to expand the applicability of benzisoxa-
zole nucleus both as antidiabetic as well as anticancer agents by targeting DPP-IV,
which was shown to have implications in diabetes and proliferation.
Figure 1. 1,2-benzisoxazole-3-acetamide derivatives with anticancer activity.

R
SYNTHETIC COMMUNICATIONSV
3
Figure 2. Design of 1,2-benzisoxazole-3-acetamide derivatives 9a–d and 11a–e as DPP-IV inhibitors.
Scheme 1. Synthesis of 1,2-benzisoxazole-3-acetamide derivatives 9a–d.
Results and discussion
Chemistry
4-Hydroxycoumarin 7 was synthesized by reacting 20-hydroxyacetophenone 5 with
diethyl carbonate 6 on pulverized sodium.[25] 1,2-Benzisoxazol-3-acetic acid 8 was pre-
pared from 4-hydroxycoumarin 7 via Posner reaction in presence of NH2OH.HCl and
NaHCO3 in methanol (Scheme 1).[26] Amide formation of 1,2-benzisoxazol-3-acetic acid
8 with various substituted amines was carried out using coupling reagents such as N-(3-
dimethylaminopropyl)-N0-ethylcarbodiimide hydrochloride (EDCI) and 1-hydroxyben-
zotriazole (HOBt) in presence of triethylamine (TEA) in dichloromethane (DCM) to
give compounds 9a–d. All compounds 9a–d were characterized using different analyt-
1
ical techniques such as H-NMR, 13C-NMR, ESI-MS, IR, etc.
1H-NMR of compound 9c showed signals for methylene protons from pyrrolidine
ring in the region of d 2.12–2.29 ppm and d 3.63–3.80 ppm, whereas methylene group
adjacent to benzisoxazole was observed at d 4.03–4.13 ppm. Signal for proton at chiral
carbon next to cyano group was observed as multiplet at d 4.73–4.75 ppm. Aromatic
protons were observed from d 7.32 to 7.87 ppm. 13C-NMR showed peaks in aliphatic
region from d 25.19 to 47.05 ppm and for aromatic carbons from d 109.80 to
163.39 ppm. Cyano group showed signal at d 118.0 ppm, whereas the amide carbon was
observed at d 166.29 ppm. ESI-MS analysis of compound 9c gave [M þ H]þ peak at
277.9 confirming the formation of desired compound.
To correlate the size of the inhibitor molecule with its activity, we have synthesized
another series of molecules having a glycine spacer. Presence of glycine spacer allowed

4
S. KARANDIKAR ET AL.
Scheme 2. 1,2-benzisoxazole-3-acetamide derivatives 11a–e.
linked group to venture deeper into the S1 pocket. Moreover, glycine spacer provided
more entropic advantage with increased rotatable bonds (Scheme 2).
Substituted aromatic amines were reacted with N-Boc-glycine using the EDCl, HOBt
strategy followed by Boc-deprotection using trifluoroacetic acid in DCM to give tri-
fluoroacetic acid (TFA) salts of compounds 10a–e. These TFA salts of compounds
10a–e were reacted with 1,2-benzisoxazol-3-acetic acid 8 using peptide coupling
reagents in presence of triethylamine to give compounds 11a–e (Scheme 2). All com-
1
pounds 11a–e were characterized using different analytical techniques such as H-NMR,
13C-NMR, ESI-MS, IR, etc.
1
The H-NMR of compound 11c showed a signal for methylene protons adjacent to
nitrogen as a doublet at d 3.96 ppm due to coupling with adjacent amide proton. The
other methylene protons adjacent to benzisoxazole ring were observed as a sharp singlet
at d 4.03 ppm. The aromatic protons gave the characteristic two groups of signals for
para substituted benzene ring in the aromatic region from d 7.34 to 7.39 ppm and d
7.59 to 7.72 ppm. The signals for benzisoxazole ring were observed d 7.35–7.40 and
7.59–7.93 ppm. The signals for one amide proton was observed d 8.79 ppm as triplet,
whereas the signal for other amide proton appeared as singlet at d 10.16 ppm. The 13C-
NMR of compound 11c showed signals for methylene carbons in aliphatic region at d
32.36 and 43.38 ppm. The signals for aromatic carbons were observed from d 109.97 to
162.79 ppm. The signals for carbonyl of amide groups were observed at d 167.97 and
168.10 ppm. ESI-MS analysis of compound 11c gave [M þ H]þ peak at 343.8 confirming
the formation of desired compound.
Biological evaluation
DPP-IV inhibition assay
Preliminary in vitro DPP-IV inhibition assay was performed to screen compounds 9a–d
and 11a–e to study effects of different amides for their inhibition potential at
25–200 mM concentrations (Figures 3 and 4).
DPP-IV inhibitory activity determined by fluorescence-based assay was measured
using Spectra Max fluorometer (Molecular Devices, CA). Values of % inhibition are

R
SYNTHETIC COMMUNICATIONSV
5
DPP-IV inhibiꢀon acꢀvity of compounds
9a-d
40
35
30
25
20
15
10
5
9a
9b
9c
9d
0
25
50
100
200
Concentraꢀon in µM
Figure 3. DPP-IV inhibition activity of 1,2-benzisoxazole-3-acetamide derivatives 9a–d.
DPP-IV inhibiꢀon acꢀvity of compounds
11a-e
70
60
11a
50
11b
40
11c
30
11d
20
11e
10
0
25
50
100
200
Concentraꢀon in µM
Figure 4. DPP-IV inhibition activity of 1,2-benzisoxazole-3-acetamide derivatives 11a–e.
mean of three independent determinations at 25–200 mM concentrations of the
test samples.
Compounds 9a–d showed poor activity for in vitro DPP-IV inhibition assay at
25–200 mM concentrations (Figure 3). Compound 9a containing pyrrolidine-2-carxoylate
group showed poor activity with 29% DPP-IV inhibition at 200 mM. Change of ester
group to stable amide group in compound 9b resulted in slight increase in activity with
33% DPP-IV inhibition at 200 mM. However, replacement of amide group by more sta-
ble and interactive cyano group in compound 9c resulted in the loss of activity with
18% DPP-IV inhibition at 200 mM concentration. Compound 9d with aminomethylpyri-
dine showed poor activity at 200 mM concentration (Figure 3) as compared to standard
Vildagliptin with 56.3% inhibition activity at 0.1 mM concentration.
In another series, compounds 11a–e containing glycine spacer showed moderate
activity for in vitro DPP-IV inhibition assay at 25–200 mM concentrations (Figure 4).
Compound 11a with 4-methyl substituent and glycine spacer, showed moderate activity
with 57% DPP-IV inhibition at 200 mM concentration as compared to standard
Vildagliptin with 56.3% inhibition activity at 0.1 mM concentration. As part of modifica-
tion and to develop structure activity relationship, 4-methyl group was replaced by

6
S. KARANDIKAR ET AL.
Table 1. Anticancer activity against A549 (Lungs cancer cell line), MCF-7 (Breast
cancer cell line) for 1,2-benzisoxazole-3-acetamide derivatives 9a–d and 11a–e.
IC50 mMa
Compound
-NR1R2
A549
MCF7
NA
9a
380.70 68.03
9b
9c
4.72 0.72
4.39 0.809
2.36 0.34
90.32 12.06
9d
6.98 0.709
NA
2.595 0.46
3.49 0.956
11a
11b
11c
59.2 19.07
10.32 3.09
5.26 0.024
11.31 1.03
11d
12.45 1.06
132.2 23.89
11.13 0.083
72.49 5.04
7.627 0.94
45.04 1.02
11e
Fluorouracil
aIC50 values were determined based on MTT assay using GraphPad Prism software.
NA: not active.
halogens in compound 11b–c. 4-Fluoro containing Compound 11b showed loss of
DPP-IV inhibition activity. However, 4-chloro containing compound 11c retained
inhibition activity. For fluoro substituted compounds, change in position from fourth to
third in compound 11d showed no significant change on DPP-IV inhibition activity
(Figure 4). Similar change of position in chloro compound 11c resulted in compound
11e with significant loss of DPP-IV inhibition activity.
DPP-IV inhibitory activity determined by fluorescence-based assay was measured
using Spectra Max fluorometer (Molecular Devices, CA). Values of % inhibition are
mean of three independent determinations at 25–200 mM concentrations of the
test samples.
Anticancer activity by MTT assay
Keeping in mind the previous studies, we screened the synthesized 1,2-benzisoxazole-3-
acetamide based DPP-IV inhibitors for their potential anticancer activity against lung
cancer cell line, A549 and breast cancer cell line, MCF-7 using MTT assay (Table 1).
The compound 9a with ester group showed poor activity with IC50 360.7 68.03 mM
against A549, this is probably because of easy in-vivo hydrolysis of the ester function
and further degradation. Replacing ester group in compound 9a with comparatively
more inert amide functional group in compound 9b resulted in good activity with IC50
values 4.72 0.72 and 4.39 0.809 mM against A549 and MCF7, respectively. However,
compound 9c with more inert cyano group showed drop in activity against A549 cell
line with IC50 90.32 12.06 mM, whereas very good activity with IC50 2.36 0.34 mM
against MCF7 cell line as compared to commercially available drug 5-fluorouracil with

R
SYNTHETIC COMMUNICATIONSV
7
IC50 45.04 1.02 mM. Interestingly, compound 9d having 3-aminomethyl pyridine
derivative of benzoisoxazole acetic acid showed good anticancer activity against A549
cell line with IC50 6.98 0.709 mM, which is comparable to 5-fluorouracil with IC50
11.13 0.083 mM. From the apparent data, it is observed that anticancer activity was
increased with increased basicity of functional group on the variable part of the mol-
ecule (Table 1).
The compound 11a having a methyl group at the fourth position was found to be
inactive against A549 cell line but showed very good activity against MCF7 cell line
with IC50 value of 3.49 0.956 mM as compared to fluorouracil with IC50 value of
45.04 1.02 mM. This might be because of increased hydrophobicity imparted by the
methyl group. Substituting the aromatic ring with halogen substituents showed a less
increase in activity against A549 cell line, whereas drop in activity against MCF7 cell
line. This could be because of increase in polarity caused by halogen atoms on the ben-
zene ring. Compound 11b with –F on fourth position was less active against A549 cell
line but showed good activity against MCF7 cell line with IC50 5.26 0.024 mM.
Compound 11c with 4-Cl group showed moderate activity against both tested cell lines.
Changing the position of fluorine from fourth position to third position in compound
11d resulted in the loss anticancer activity with against MCF7 cell line, whereas
remained moderately active against A549 cell line with IC50 12.45 1.06 mM. Similar
change in position of chloro from fourth position to third position in compound 11e
resulted in loss of anticancer activity against A549 cell line but retained moderate activ-
ity against MCF7 cell line with IC50 value 7.627 0.94 mM.
Conclusion
We have designed and synthesized various benzisoxazole acetamide derivatives with and
without glycine spacer. It is observed that compounds 11a–e with glycine spacer showed
better DPP-IV inhibition than compound 9a–d without glycine spacer. Interestingly,
compounds 9a–d without glycine spacer are showing good anticancer activity compared
to compounds 11a–e. Compound 9b is showing moderate activity with IC50 values
4.72 0.72 and 4.39 0.809 mM against A549 and MCF7 cell lines, respectively, and
compound 9c with cyano group is showing very good activity with IC50 2.36 0.34 mM
against MCF7 cell line. It is observed that DPP-IV inhibition can be promising strategy
for modulating diabetes as well as cancer, and it should be explored further.
Experimental
Chemistry
Reagent grade chemicals and solvents were purchased from commercial supplier and
used after purification. TLC was performed on silica gel F254 plates (Merck). Acme’s
silica gel (60–120 mesh) was used for column chromatographic purification. All reac-
tions were carried out in nitrogen atmosphere. Melting points are uncorrected and were
measured in open capillary tubes using a Rolex melting point apparatus. IR spectra
1
were recorded as KBr pellets on Perkin Elmer RX 1 spectrometer. H NMR and 13C
NMR spectral data were recorded on Advance Bruker 400 spectrometer (400 MHz) with

8
S. KARANDIKAR ET AL.
CDCl3 or DMSO-d6 as solvent and TMS as internal standard. J values are in Hz. Mass
spectra were determined by ESI-MS using a Shimadzu LCMS 2020 apparatus. Elemental
analyses were recorded on Thermosinnigan Flash 11-12 series EA. All reactions were
carried out under nitrogen atmosphere. (S) ethyl pyrrolidine-2-carboxylate, (S) pyrroli-
dine-2-carboxamide, (S) pyrrolidine-2-carbonitrile, and (S) piperidine-2-carboxamide
were prepared according to the literature method.[27]
General procedure for the preparation of compounds 9a–d and 11a–e
To an ice cold solution of 1,2-benzisoxazol-3-acetic acid 8 (1.0 mmol, 1.0 eq.), N-(3-
dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride (1.5 mmol, 1.5 eq.), and 1-
hydroxybenzotriazole (1.0 mmol, 1.0 eq) in DCM (25 mL) was added solution of TFA
salt of proline derivative/3-aminomethyl pyridine/compound 10 (1.0 mmol, 1.0 eq.) and
triethylamine (2.5 mmol, 2.5 eq.) in DCM (5 mL). The reaction mixture was stirred at
0–5 ꢀC for 30 min and at room temperature for overnight. The completion of the reac-
tion was monitored using TLC analysis using pet.ether:ethyl acetate (1:1). The reaction
mixture was concentrated on a rotavapor to give crude residue. The residue was dis-
solved in ethyl acetate (50 mL) and was washed with water (2 ꢁ 25 mL), 0.5 N HCl solu-
tion (2 ꢁ 10 mL), saturated NaHCO3 (2 ꢁ 15 mL), and brine (20 mL). The organic layer
was separated, dried over anhydrous sodium sulfate, filtered, and concentrated to give
crude compound. The compounds were purified by column chromatography using pet
ether: ethyl acetate from 9:1 to 2:8 to give pure compounds 9a–d and 11a–e solid.
Characterization data for compound 9a and 11a
Ethyl 1-2-(benzo[d]isoxazol-3-yl)acetyl)pyrrolidine-2-carboxylate (9a). White solid, Yield:
36%; M.P: 44–46 ꢀC; IR (KBr) 2976, 2945, 2893, 1664, 1654, 1608, 1427, 1294, 864,
1
750 cmꢂ1; H-NMR (400 MHz, CDCl3): d 1.17 (t, J ¼ 7.2 Hz, 2H), 1.9 (t, J ¼ 7.2 Hz, 1H),
1.97–2.03 (m, 3H), 2.17–2.20 (m, 1H), 3.70–3.72 (m, 1H), 3.80–3.94 (m, 1H), 3.98–4.17
(m, 4H), 4.47–4.50 (m,1H), 7.30–7.35 (m, 1H), 7.55–7.56 (m, 2H), 7.88 (t, J ¼ 8.0 Hz,
1H); 13C-NMR (100 MHz, CDCl3): d 14.16, 24.81, 29.25, 32.79, 47.67, 59.22, 61.20,
109.63, 122.84, 123. 62, 130.03, 153.39, 163.30, 166.02, 171.80, 171.87; Anal. Calc. for
C16H18N2O4; C, 63.56; H, 6.00; N, 9.27; found: C, 63.42; H, 6.20; N, 9.35%; ESI-MS:
273.10 [M-29].
2-(Benzo[d]isoxazol-3-yl)-N-(2-oxo-2-(p-tolylamino)ethyl)acetamide (11a). Off white solid,
Yield: 53%; M.P: 190–192 ꢀC; IR (KBr) 3377, 3312, 3287, 2919, 2858, 1697, 1657, 1608,
1
1550, 1439, 1237, 852, 819, 762 cmꢂ1; H-NMR (400 MHz, CDCl3): d 2.24 (s, 3H), 3.94
(s, 2H), 4.03 (s, 2H), 7.11 (d J ¼ 6.8 Hz, 2H), 7.38-7.49 (m, 3H), 7.64–7.73 (m, 2H), 7.93
(d, J ¼ 6.8 Hz,1H), 8.85 (br s, 1H), 9.98 (br s, 1H); 13C-NMR (100 MHz, CDCl3): d
20.90, 32.37, 43.33, 109.98, 119.59, 121.87, 123.34, 124.00, 129.60, 130.72, 132.64, 136.79,
154.84, 162.77, 167.68, 167.92; Anal. Calc. for C18H17N3O3; C, 66.86; H, 5.30; N, 13.00;
found: C, 66.91; H, 5.43; N, 13.23%; ESI-MS: 323.9 [M þ H]þ and 345.9 [M þ Na]þ.

R
SYNTHETIC COMMUNICATIONSV
9
Synthesis of compounds 8 and 10, full characterization data for compounds 9b–d
and 11b–e, and detailed methods for biological activities are provided in supporting
information.
Acknowledgments
One of the authors (SU) is thankful to UGC, Government of India for UGC-JRF vide reference
no. 22/06/2014 (i) EU-V. Authors are thankful to The Head, Department of Chemistry and
Department of Zoology, Faculty of Science, The M. S. University of Baroda for providing labora-
tory facilities and Zydus Research Centre, Ahmedabad, for the ESI-MS analyses.
Disclosure statement
The authors declare that there is no conflict of interest regarding the publication of this paper.
Funding
One of the authors (RS) is thankful to Department of Science and Technology, Government of
India for financial support vide reference no. SR/WOS-A/CS-1028/2014 under Women Scientist
Scheme to carry out this work.
References
[1] Drucker, D. J.; Nauck, M. A. The Incretin System: Glucagon-Like Peptide-1 Receptor
Agonists and Dipeptidyl Peptidase-4 Inhibitors in Type 2 Diabetes. Lancet 2006, 368,
1696–1705. DOI:10.1016/S0140-6736(06)69705-5
[2] Kshirsagar, A. K.; Aggarwal, A. S.; Harle, U. N.; Deshpande, A. V. DPP IV Inhibitors:
Successes, Failures and Future Prospects. Diabetes Metab. Syndr. 2011, 5, 105–112.
DOI:10.1016/j.dsx.2012.02.017
[3] Abbott, C. A.; McCaughan, G. W.; Baker, E.; Sutherland, G. R. Genomic Organization,
Exact Localization, and Tissue Expression of the Human CD26 (Dipeptidyl Peptidase IV)
Gene. Immunogenetics 1994, 40, 331–338. DOI:10.1007/BF01246674
[4] Cheng, H. C.; Abdel-Ghany, M.; Elble, R. C.; Pauli, B. U. Lung Endothelial Dipeptidyl
Peptidase IV Promotes Adhesion and Metastasis of Rat Breast Cancer Cells via Tumor
Cell Surface-Associated Fibronectin. J. Biol. Chem. 1998, 273, 24207–24215. DOI:10.1074/
jbc.273.37.24207
[5] Wesley, U. V.; Albino, A. P.; Tiwari, S.; Houghton, A. N. A Role for Dipeptidyl Peptidase
IV in Suppressing the Malignant Phenotype of Melanocytic Cells. J. Exp. Med. 1999, 190,
311–322. DOI:10.1084/jem.190.3.311
[6] Pethiyagoda, C. L.; Welch, D. R.; Fleming, T. P. Dipeptidyl Peptidase IV (DPPIV) Inhibits
Cellular Invasion of Melanoma Cells. Clin. Exp. Metastasis. 2000, 18, 391–400.
DOI:10.1023/A:1010930918055
[7] Aytac, U.; Clart, F. X.; Ho, L.; Sato, K.; Ohnuma, K.; Mills, G. B.; Cabanillas, F.;
Morimoto, C.; Dang, N. H. Expression of CD26 and Its Associated Dipeptidyl Peptidase
IV Enzyme Activity Enhances Sensi-Tivity to Doxorubicin-Induced Cell Cycle Arrest at
the G(2)/M Checkpoint. Cancer Res. 2001, 61, 7204–7210.
[8] (a) Villhauer, E. B.; Brinkman, J. A.; Naderi, G. B.; Burkey, B. F.; Dunning, B. E.; Prasad,
K.; Mangold, B. L.; Russell, M. E.; Hughes, T. E. 1-[[(3-Hydroxy-1-
Adamantyl)Amino]Acetyl]-2-Cyano-(S)-Pyrrolidine:
A Potent, Selective, and Orally
Bioavailable Dipeptidyl Peptidase IV Inhibitor with Antihyperglycemic Properties. J. Med.
Chem. 2003, 46, 2774–2789. (b) Kim, D.; Wang, L.; Beconi, M.; Eiermann, G. J.; Fisher,

10
S. KARANDIKAR ET AL.
M. H.; He, H.; Hickey, G. J.; Kowalchick, J. E.; Leiting, B.; Lyons, K.; et al. (2R)-4-Oxo-4-
[3-(Trifluoromethyl)-5,6-Dihydro[1,2,4]Triazolo[4,3-a]Pyrazin-7(8H)-Yl]-1-(2,4,5-
Trifluorophenyl)Butan-2-Amine:
A Potent, Orally Active Dipeptidyl Peptidase IV
Inhibitor for the Treatment of Type 2 Diabetes. J. Med. Chem. 2005, 48, 141–151.
[9] Biftu, T.; Sinha-Roy, R.; Chen, P.; Qian, X.; Feng, D.; Kuethe, J. T.; Scapin, G.; Gao, Y. D.;
Yan, Y.; Krueger, A.; et al. Omarigliptin (MK-3102): A Novel Long-Acting DPP-4
Inhibitor for Once-Weekly Treatment of Type 2 Diabetes. J. Med. Chem. 2014, 57,
3205–3212.
[10] Hansen, J.; Deacon, C. F.; Orskov, C.; Holst, J. J. Glucagon-like Peptide-1-(7–36)Amide is
Transformed to Glucagon-like Peptide-1-(9–36)Amide by Dipeptidyl Peptidase IV in the
Capillaries Supplying the L Cells of the Porcine Intestine. Endocrinology 1999, 140,
5356–5363.
[11] (a) Dang, N. H.; Morimoto, C. CD26: An Expanding Role in Immune Regulation and
Cancer. Histol. Histopathol. 2002, 1. 1213–1226. (b) Iwata, S.; Morimoto, C. CD26/
Dipeptidyl Peptidase IV in Context. The Different Roles of a Multifunctional Ectoenzyme
in Malignant Transformation. J. Exp. Med 1999, 190, 301–306.
[12] Liotta, L. A.; Kohn, E. C. The Microenvironment of the Tumour-Host Interface. Nature
2001, 411, 375–379.
ꢀ
ꢀ
[13] Busek, P.; Malik, R.; Sedo, A. Dipeptidyl Peptidase IV Activity and/or Structure
Homologues (DASH) and Their Substrates in Cancer. Int. J. Biochem. Cell Biol. 2004, 36,
408–421.
[14] Deng, B. L.; Zhao, Y.; Hartman, T. L.; Watson, K.; Buckheit, R. W.Jr; , Pannecouque, C.;
Clercq, E. D.; Cushman, M. Synthesis of Alkenyldiarylmethanes (ADAMs) Containing
Benzo[d]Isoxazole and Oxazolidin-2-One Rings, a New Series of Potent Non-Nucleoside
HIV-1 Reverse Transcriptase Inhibitors. Eur. J. Med. Chem. 2009, 44, 1210–1214.
[15] Lamani, R. S.; Shetty, N. S.; Kamble, R. R.; Khazi, I. A. M. Synthesis and Antimicrobial
Studies of Novel Methylene Bridged Benzisoxazolyl Imidazo[2,1-b][1,3,4]Thiadiazole
Derivatives. Eur. J. Med. Chem. 2009, 44, 2828–2833.
[16] (a) Aiello, S.; Wells, G.; Stone, E. L.; Kadri, H.; Bazzi, R.; Bell, D. R.; Stevens, M. F. G.;
Matthews, C. S.; Bradshaw, T. D.; Westwel, A. D. Synthesis and Biological Properties of
Benzothiazole, Benzoxazole, and Chromen-4-One Analogues of the Potent Antitumor
Agent 2-(3,4-Dimethoxyphenyl)-5-Fluorobenzothiazole (PMX 610, NSC 721648). J. Med.
Chem. 2008, 51, 5135–5139. (b) Arakawa, K.; Inamasu, M.; Matsumoto, M.; Okumura, K.;
Yasuda, K. Novel Benzoxazole-2,4-Thiazolidinediones as Potent Hypoglycemic Agents.
Synthesis and Structure-Activity Relationships. Chem. Pharm. Bull. 1997, 45, 1984–1993.
[17] Sharath Chandra, S. P.; Vishwaprakash Mahadimane, P. Effect of Novel Benzisoxazole
Derivatives against Ehrlich Ascites Carcinoma Cells in Swiss Albino Mice: Cytotoxic and
Haematological Studies. Int. J. Pharma Sci. Res. 2015, 6, 3606–3611.
[18] Rajashekar, R. C. B.; Reddy, R.; Revathy, S. T.; Krish, S.; Sabiah, S. Res. J. Pharm. Biol.
Chem. Sci. 2014, 5, 873–880.
[19] Shi, G. Q.; Dropinski, J. F.; McKeever, B. M.; Xu, S.; Becker, J. W.; Berger, J. P.; MacNaul,
K. L.; Elbrecht, A.; Zhou, G.; Doebber, T. W.; et al. Design and Synthesis of
a-Aryloxyphenylacetic Acid Derivatives: A Novel Class of PPARa/c Dual Agonists with
Potent Antihyperglycemic and Lipid Modulating Activity. J. Med. Chem. 2005, 48,
4457–4468.
[20] Benaka Prasad, S. B.; Vinaya, K.; Ananda Kumar, C. S.; Swarup, S.; Rangappa, K. S.
Synthesis of Novel 6-Fluoro-3-(4-Piperidinyl)-1,2-Benzisoxazole Derivatives as
Antiproliferative Agents: A Structure–Activity Relationship Study. Invest. New Drugs 2009,
27, 534–542.
[21] Ashwini, N.; Garg, M.; Mohan, C. D.; Fuchs, J. F.; Rangappa, S.; Anusha, S.; Swaroop,
T. R.; Rakesh, K. S.; Kanojia, D.; Madan, V.; et al. Synthesis of 1,2-Benzisoxazole Tethered
1,2,3-Triazoles That Exhibit Anticancer Activity in Acute Myeloid Leukemia Cell Lines by
Inhibiting Histone Deacetylases, and Inducing p21 and Tubulin Acetylation. Bioorg. Med.
Chem. 2015, 23, 6157–6165.

R
SYNTHETIC COMMUNICATIONSV
11
[22] (a) Soni, R.; Durgapal, S.; Soman, S. S.; Georrge, J. J. Design, Synthesis and anti-Diabetic
Activity of Chromen-2-One Derivatives. Arabian J. Chem. 2016, DOI:10.1016/
j.arabjc.2016.11.01. (b) Sharma, R.; Soman, S. S. Design and Synthesis of Sulfonamide
Derivatives of Pyrrolidine and Piperidine as anti-Diabetic Agents. Eur. J. Med. Chem.
2015, 90, 342–350.
[23] Patel, J. M.; Soman, S. S. Studies on the Synthesis of Furobenzisoxazole Derivatives. Chem.
Heterocycl. Comp. 2009, 45, 1081–1088.
[24] Soman, S. S.; Soni, J.; Patel, T. Synthesis of New Naphthoisoxazole Amide Derivatives and
Study of Their Biological Evaluations. Med. Chem. Res. 2014, 23, 3803–3809.
[25] Boyd, J.; Robertson, A. The Chemistry of the “Insoluble Red” Woods. Part II. A New
Synthesis of 4-Hydroxycoumarins. J. Chem. Soc. 1948, 0, 174–176.
[26] Posner, I.; Hess, R. Unsaturated Compounds. X. Action of Free Hydroxylamine on
Coumarins. Ber. Dtsch. Chem. Ges. 1913, 46, 3816–3833.
[27] (a) Almansa, R.; Guijarro, D.; Meyers, A. Enantioselective Addition of Dialkylzinc
Reagents to N-(Diphenylphosphinoyl)Imines Catalyzed by b-Aminoalcohols with the
Prolinol Skeleton. Tetrahedron Asymmetry 2007, 18, 2828–2840. (b) Tang, F. Y.; Qu,
L. Q.; Xu, Y.; Ma, R. J.; Chen, S. H.; Li, G. Practical Synthesis of Structurally Important
Spirodiamine Templates. Synt. Commun. 2007, 37, 3793–3799.