Design, synthesis and docking studies on phenoxy-3-piperazin-1-yl-propan-2- ol derivatives as protein tyrosine phosphatase 1B inhibitors

Article abstract of DOI:10.1016/j.bmcl.2010.08.008

A series of substituted phenoxy-3-piperazin-1-yl-propan-2-ols has been synthesized and evaluated for PTP1B inhibitory activity in vitro and for antidiabetic activity in vivo. Two molecules viz. 4a and 5b showed PTP1B inhibition of 31.58% and 35.90% at 100

Full text of DOI:10.1016/j.bmcl.2010.08.008

Bioorganic & Medicinal Chemistry Letters 20 (2010) 5732–5734
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Design, synthesis and docking studies
on phenoxy-3-piperazin-1-yl-propan-2-ol derivatives as protein tyrosine
phosphatase 1B inhibitors q
Swati Gupta a, Gyanendra Pandey a, Neha Rahuja b, Arvind K. Srivastava b, Anil K. Saxena a,
*
a Medicinal and Process Chemistry Division, Central Drug Research Institute, C.S.I.R. Lucknow 226001, India
b Biochemistry Division, Central Drug Research Institute, C.S.I.R. Lucknow 226001, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of substituted phenoxy-3-piperazin-1-yl-propan-2-ols has been synthesized and evaluated for
Received 2 June 2010
Revised 2 August 2010
Accepted 3 August 2010
Available online 7 August 2010
PTP1B inhibitory activity in vitro and for antidiabetic activity in vivo. Two molecules viz. 4a and 5b
showed PTP1B inhibition of 31.58% and 35.90% at 100 lM concentration. The compound 4a also showed
40.3% normalization of plasma glucose levels at 100 mg/kg in Sugar-loaded model (SLM) and 32% activity
in Streptozodocin model (STZ). The docking studies of these molecules revealed that hydrogen bond
formation with Arg221 is important for activity.
Keywords:
Protein tyrosine phosphatases 1B
Docking
Ó 2010 Elsevier Ltd. All rights reserved.
Protein tyrosine phosphatases (PTPases) belong to the protein
phosphatases which include protein serine/threonine phospha-
tases (PSTPs). The PTPases are often related to cellular dysfunction
and play an important role in different diseases viz. diabetes, obes-
ity, inflammation, cancer and neurodegeneration.1–3 Among these,
type-2 diabetes and obesity are related with the deficiency in insu-
lin receptor signaling and is supposed to be recovered by the inhi-
bition of a certain PTPase(s) including prolonged phosphorylation
of the insulin receptor kinase.4–7 The protein tyrosine phosphatase
1B (PTP1B) plays a key role in cellular signaling and in several
human diseases, particularly diabetes and obesity.8–10 It is an
intracellular non-receptor PTPase and is expressed in a large vari-
ety of human tissues.11 It inhibits the insulin receptor (IR) through
dephosphorylation. The PTP1B knockout mice improve glucose tol-
erance and enhance insulin sensitivity as a result of improved insu-
lin action in skeletal and liver muscle without affecting insulin
action in adipose tissue. In addition, disorder of PTP1B gene in mice
unexpectedly protects the mice against obesity when placed on a
high fat diet.4,12 Hence potent, orally active and selective PTP1B
inhibitors are considered as potential pharmacological agents for
the treatment of obesity and NIDDM.13 Several series of PTP1B
the substructural analysis approach, a series of phenoxy-3-pipera-
zin-1-yl-propan-2-ol was designed and evaluated for in vitro
PTP1B inhibitory activity and in vivo antidiabetic activity in SLM
and STZ models. The general route for the synthesis of phenoxy-
3-piperazin-1-yl-propan-2-ol derivatives is outlined in Scheme 1.
The condensation of various substituted phenols (1) with epichlo-
rohydrin in the presence of bases like NaOH or NaH, in THF at
100 °C gave two products; 2-(phenoxymethyl)oxirane (2) and
1,3-diphenoxy-propan-2-ol (3), which were characterized by the
PMR and mass spectroscopy. The condensation of para substituted
2-(phenoxymethyl) oxirane (2) with different substituted piper-
zines in ethanol at 80 °C gave the required compounds20 (4a–6).
The synthesized compounds were evaluated in vitro for their
PTP1B inhibitory activity at 100 lM dose according to Goldstein
R
R
R
+
R
(i)
OH
O
O
O
O
OH
(3)
(1)
(2)
inhibitors including 2-(oxalylarylamino)-benzoic acids,14
a-keto
(ii)
acids,15 aminothiazoles,16 formylchromanes,17 isothiazolidinone
derivatives,18 2-(4-methoxyphenyl) ethyl] acetamide derivatives,19
have been reported in recent years. In view of the above and using
R
R1
O
N
N R2
OH
4a-6
q
CDRI Communication No. 84/2010/AKS.
* Corresponding author. Tel.: +91 522 2612411x18; fax: +91 522 2623405.
E-mail address: anilsak@gmail.com (A.K. Saxena).
Scheme 1. Synthesis of compound 4a-6. Reagents and conditions: (i) epichlorohy-
drin, NaOH or NaH, THF, 100 °C; (ii) ethanol, 80 °C, various substituted piperzines.
0960-894X/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2010.08.008

S. Gupta et al. / Bioorg. Med. Chem. Lett. 20 (2010) 5732–5734
5733
method using Na-orthovanadate and peroxovanadate as a refer-
ence standard.21 The molecules were screened for in vivo activity
in SLM and STZ models in rat. The results of the in vitro inhibition
assays are reported in Table 1, which indicated that the inhibitory
effects of these analogues differed markedly due to the substituent
variation in the phenoxyphenyl ring. Among these, the most active
analogue 5b having 4-Cl group at R and 4-nitrophenyl group at R2
showed good in vitro inhibitory activity (% inhibition = 35.9% at
pan-2-ol (5b) and 4-[2-hydroxy-3-(3-methyl-4-p-tolyl-piperazin-
1-yl) propoxy]benzonitrile (4a) in the binding sites of PTP1B were
considered. Detailed binding pattern of compound 5b exhibiting
the highest inhibition value of 35.90% at 100 lM and GOLD score
value 60.03, is shown inFigure 1. The one oxygen of the nitro group
of 5b showed one hydrogen bonding interaction with the –NH2 of
Arg221 and two with Cys215 while the other oxygen of the nitro
group of 5b showed three hydrogen bonding interactions with
the –NH2 of Arg221 only. The one –NH group of piperazine moiety
of compound 5b also showed hydrogen bond interaction with
water molecule (HOH:590) similar to the one observed in case
of –NH in the sulfamic acid.19 The docking studies of the compound
100
lM). The replacement of 4-Cl group with 4-F group (6) at R po-
sition resulted in slight reduction in PTP1B inhibitory activity (%
inhibition = 24.0% at 100 lM). The compound 4a, with 4-CN group
at R, Me group at R1 and 4-methylphenyl substituents at R2
resulted in almost equal activity (% inhibition = 31.58% at
1a having inhibition value of 31.58% at 100 lM and GOLD score
100
l
M). Insertion of 4-fluorophenyl (4c), 3-chlorophenyl (4d) 2-
value of 52.81 showed three hydrogen bonding interactions be-
tween the cyano group attached to the para position of the phenyl
ring and Arg221. The –OH of the compound 4a also showed hydro-
gen bonding interaction with the carbonyl group of Gln262 (Fig. 2).
It was also similar to the one shown by the –NH in the case of sul-
famic acid.19 These studies correlated well with the observed
PTP1B inhibitory activity. In view of their good inhibitory activity,
these compounds were further evaluated for their antidiabetic
activities in the SLM and STZ models in rats, essentially according
to the recently reported procedure from our laboratory.24 The most
methoxyphenyl (4e), phenyl (4f), 2-pyridine (4g), 5-Me-benzo1,
3 dioxole (4h) and benzyl group (4i) at R2 position keeping 4-CN
group constant at R position, resulted in total loss in the activity
whereas the compound 4b, with 4-CN group at R and 3-CF3 group
at R2 was two time less active than the lead compound 5b. A care-
ful analysis revealed that the Cl group at the para position of the
phenyl ring was favorable for the inhibitory activity. To confirm
this finding, we synthesized four analogues with 4-Cl substituent
at R and 4-methoxyphenyl (5a), 3,4-dichlorophenyl (5c), cinnamyl
(5d) and 4-Me (5e) at R2 position, respectively. Since these ana-
logues showed no enhancement in the activity, it was thought that
the reason behind these unexpected results may be due to the poor
solubility of these compounds.
In order to add more insight into the binding mode of these
compound with the enzyme of known X-ray structure, the docking
studies were carried out using Genetic Optimisation for Ligand
Docking (GOLD) software version 2.2 on windows based PC.22 The
reported crystal structure of PTP1B with co-crystal of sulfamic acid
derivative with 2.0 Å resolution, was downloaded from Protein
Data Bank (PDB) ID 2F70 and was used for the current docking
studies. The docked poses were scored using GOLD score. Origi-
nally the protein was considered without ligand and water mole-
cule for the purpose of docking studies. The Protein–ligand
complexes of PTP1B (PDB-2F70) were minimised up to a gradient
of 0.01 kcal/(mol Å) and hydrogens were added using the CHARMm
force field, available in the software discovery studio 2.0.23 On con-
cluding point of docking process the resulting conformation poses
of 1-(4-chlorophenoxy)-3-(4-(4-nitrophenyl)piperazin-1-yl)pro-
Figure 1. Interaction of the 5b (green) with the amino acids in the active site of
PTP-1B (PDB ID 2F70).
Table 1
In vitro PTP1B enzyme inhibitory and in vivo antihyperglycemic activity in SLM and STZ model for compounds 4a–6
Compd
R
R1
R2
% Inhibition (100
l
M)
SLMa
STZb
5 h
24 h
4a
4b
4c
4d
4e
4f
4g
4h
4i
5a
5b
5c
5d
5e
6
CN
CN
CN
CN
CN
CN
CN
CN
CN
Cl
Cl
Cl
Cl
Cl
F
Me
H
H
H
H
H
H
H
H
H
H
H
H
H
H
—
—
—
4-MePh
3-CF3Ph
4-FPh
3-ClPh
2-OMePh
Ph
2-Pyridine
5-Me-benzo1,3dioxole
Benzyl
4-OMePh
4-NO2Ph
3,4-diClPh
Cinnamyl
4-Me
À31.58
À18.8
À3.60
À1.50
À2.6
À40.3
+49.7
+38.6
+16.5
+33.5
+56.7
+39.6
+14.0
À39.6
À4.60
À24.8
+3.52
À14.6
+2.61
À40.2
—
26.8
—
—
—
—
—
—
—
25.3
—
32
—
—
—
—
—
—
—
14.7
—
À4.6
À1.80
À0.50
À5.10
À9.21
À35.9
+24.6
À7.63
+2.4
À24.0
À39.4
À56.0
—
18.9
—
13.6
—
4-NO2Ph
—
—
14.4
—
—
10.8
—
—
Na-orthovanadate
Peroxovanadate
Metformin
—
À42.0
—
28.0
29.8
a
Sucrose loaded mouse (SLM).
Streptozodocin (STZ) model.
b

5734
S. Gupta et al. / Bioorg. Med. Chem. Lett. 20 (2010) 5732–5734
Acknowledgements
Authors are thankful to Messers Z. Ali and A.S. Kushwaha for the
technical assistance; SAIF, Lucknow, for providing spectroscopic
data and Network project on Diabetes mellitus new drug discovery
R&D for the financial supports. One of the authors S.G. is thankful
to ICMR, New Delhi for the fellowship.
References and notes
1. Zhang, Z.-Y. Curr. Opin. Chem. Biol. 2001, 5, 416.
2. Van Huijsduijnen, R. H.; Bombrun, A.; Swinnen, D. Drug Discovery Today 2002,
7, 1013.
3. Li, L.; Dixon, J. E. Semin. Immunol. 2000, 12, 75.
4. Elchebly, M.; Payette, P.; Michaliszyn, E.; Cromlish, W.; Collins, S.; Loy, A. L.;
Normandin, D.; Cheng, A.; Himms-Hagen, J.; Chan, C. C.; Ramachandran, C.;
Gresser, M. J.; Tremblay, M. L.; Kennedy, B. P. Science 1999, 283, 1544.
5. Zinker, B. A.; Rondinone, C. M.; Trevillyan, J.; Gum, R. J.; Clampit, J. E.; Waring, J.
F.; Xie, N.; Wilcox, D.; Jacobson, P.; Frost, L.; Kroeger, P. E.; Reilly, R. M.;
Koterski, S.; Opgenorth, T. J.; Ulrich, R. G.; Crosby, S.; Butler, M.; Murray, S. F.;
McKay, R. A.; Bhanot, S.; Monia, B. P.; Jirousek, M. R. Proc. Natl. Acad. Sci. U.S.A.
2002, 99, 11357.
6. Rondinone, C. M.; Trevillyan, J. M.; Clampit, J.; Gum, R. J.; Berg, C.; Kroeger, P.;
Frost, L.; Zinker, B. A.; Reilly, R.; Ulrich, R.; Butler, M.; Monia, B. P.; Jirousek, M.
R.; Waring, J. F. Diabetes 2002, 51, 2405.
7. Ramachandran, C.; Kennedy, B. P. Curr. Top. Med. Chem. 2003, 3, 749.
8. Andersen, J. N.; Mortensen, O. H.; Peters, G. H.; Drake, P. G.; Iversen, L. F., et al
Mol. Cell. Biol. 2001, 21, 7117.
Figure 2. Interaction of the 4a (green) with the amino acids in the active site of
PTP-1B (PDB ID 2F70).
active compound 5b showed 24.8% activity in SLM model and
18.9% (5 h) and 13.6% (24 h) in STZ model while the compound
4a which was the second most active analogue in vitro, showed
40.3% blood glucose lowering activity in SLM model and 26.8%
(5 h) and 32% (24 h) in STZ model (Figs. 3 and 4). Unlike in vitro,
where the analogue 6 and 4i which showed lesser activity viz.
9. Hooft van Huijsduijnen, R. Gene 1998, 225, 1.
24.0% and 5.10% at 100 lM, respectively than 5b (35.9%) lowered
10. Walchli, S.; Colinge, J.; Hooft van Huijsduijnen, R. Gene 2000, 253, 137.
11. Chernoff, J.; Schievella, A. R.; Jost, C. A.; Erikson, R. L.; Neel, B. G. Proc. Natl. Acad.
Sci. U.S.A. 1990, 87, 2735.
12. Klaman, L. D.; Boss, O.; Peroni, O. D.; Kim, J. K.; Martino, J. L.; Zabolotny, J. M.;
Moghal, N.; Lubkin, M.; Kim, Y. B.; Sharpe, A. H.; Stricker-Krongrad, A.;
Shulman, G. I.; Neel, B. G.; Kahn, B. B. Mol. Cell. Biol. 2000, 20, 5479.
13. Gum, R. J.; Gaede, L. L.; Koterski, S. L.; Heindel, M.; Clampit, J. E.; Zinker, B. A.;
Trevillyan, J. M.; Ulrich, R. G.; Jirousek, M. R.; Rondinone, C. M. Diabetes 2003,
52, 21.
blood glucose level very significantly 40.2% and 39.6%, respectively.
These compounds were also active in STZ model where compound
6 showed lowering of blood glucose level 11% (5 h) and 4.48%
(24 h) and the compound 4i showed 25.3% (5 h) and 14.7%
(24 h), respectively. Thus new lead series of phenoxy-3-pipera-
zin-1-yl-propan-2-ol derivatives may be useful in the optimization
of PTP1B inhibitory activity.
14. Andersen, H. S.; Iversen, L. F.; Jeppesen, C. B.; Branner, S.; Norris, K.; Rasmussen,
H. B.; Møller, K. B.; Møller, N. P. H. J. Biol. Chem. 2000, 275, 7101.
15. Chen, Y. T.; Seto, C. T. J. Med. Chem. 2002, 45, 3946.
16. Wipf, P.; Aslan, D. C.; Southwick, E. C.; Lazo, J. S. Bioorg. Med. Chem. Lett. 2001,
11, 313.
17. Shim, Y. S.; Kim, K. C.; Chi, D. Y.; Lee, K.-H.; Cho, H. Bioorg. Med. Chem. Lett.
2003, 13, 2561.
150
Control
4a
4i
18. Combs, A. P. et al J. Med. Chem. 2006, 49, 3774.
100
19. Saxena, A.; Pandey, G.; Gupta, S. Bioorg. Med. Chem. Lett. 2009, 19, 2320.
20. General method for the synthesis of oxiranylmethoxy-benzonitrile (2): A solution
of 4-cynophenol (57, 2.38 g, 0.02 mol) in ethanol was stirred with sodium
hydroxide (0.80 g, 0.02 mol) for ½ h at rt. Epichlorohydrin (1.84 g, 0.02 mol)
was added and reaction mixture was stirred at room temperature for 12 h. The
mixture was concentrated under reduced pressure, extracted with ethyl
acetate (3 Â 10 ml), dried on sodium sulphate and was concentrated. Yield:
57.1%; mp: 80 °C; 1H NMR (CDCl3, 200 Hz): d 2.74–2.78 (m, 1H), 2.91–2.95 (m,
1H), 3.34–3.39 (m, 1H), 3.92–4.01 (m, 1H), 4.29–4.36 (m, 1H), 7.55–7.62 (m,
2H), 6.94–7.00 (m, 2H); FTIR (KBr): cmÀ1 767, 1089, 1222, 1505, 2923, 2225;
FAB-MS: m/z 176 (M+1)+. 1,3-Bis-p-cyanophenoxy-propan-2-ol (3): Yield:
(70.5%), mp 120 °C; 1H NMR (CDCl3, 200 Hz): d 2.60 (br s, 1H), 4.44 (m, 1H),
4.20–4.22 (m, 4H), 6.99 (d, J = 9.0 Hz, 4H), 7.60 (d, J = 9.0 Hz, 4H); FTIR (KBr):
cmÀ1 832, 1055, 1261, 1603, 2218, 2932, 3421; FAB-MS: m/z 295 (M+1)+. Anal.
Calcd for C17H14N2O3: C, 69.38; H, 4.76; N, 9.52. Found: C, 69.40; H, 4.77; N,
9.53. 4-[2-Hydroxy-3-(3-methyl-4-p-tolyl-piperazin-1-yl)-propoxy] benzonitrile
(4a): A solution of 4-oxiranylmethoxy-benzonitrile (2, 0.875 g, 0.005 mol)
and 2-methyl-1-p-tolylpiperazine (1.05 ml, 0.005 mol) in ethanol (10.0 ml)
was stired at rt for 6 h. The mixture was concentrated under reduced pressure
and crystallized by methanol. Yield: 70.8%; mp: 125 °C; 1H NMR (CDCl3,
200 Hz): d 1.03 (d, J = 6.2, 3H), 2.28 (s, 3H), 2.48-2.84 (m, 7H), 3.14–3.70 (m,
2H), 3.72 (br s, 1H), 4.07–4.17 (m, 3H), 6.85 (d, J = 8.0 Hz, 2H), 6.97–7.10 (m,
4H), 7.59 (d, J = 8.6 Hz, 2H); FTIR (KBr): cmÀ1 670, 769, 1257, 1352, 1600, 2221,
2936, 3430; FAB-MS: m/z 366 (M+1)+. Anal. Calcd for C22H27N3O2: C, 72.32; H,
7.39; N, 11.53. Found: C, 72.35; H, 7.41; N, 11.55. Compounds 4b–6 were
synthesized similarly.
5b
6
Metformin
50
0
0
30
60
90
120
Time (min)
Figure 3. Effect of Compounds 4a, 4i, 5b and
(100 mg/kg) on the blood glucose levels of normoglycemic rats.
6 (100 mg/kg), and metformin
600
500
400
300
200
100
0
CONTROL
4a
4i
6
21. Goldstein, B. J.; Bittner-Kowalczyk, A.; White, M. F.; Harbeck, M. J. Biol. Chem.
2000, 275, 4283. Assay mixture containing 10 mM PNPP in 50 mM HEPES
buffer (pH 7.0), with 1 mM EDTA and DTT was made up to 1 ml. The reaction
was stopped by the addition of 500 ll of 0.1 N NaOH and absorbance was
determined at 410 nm. A molar extinction coefficient of 1.78 Â 104 MÀ1 cmÀ1
was used to calculate the concentration of p-nitrophenolate ions produced in
the reaction mixture..
5b
Metformin
0
50
100
150
200
250
301042014301440
22. GOLD; Version 3.2; Cambridge Crystallographic Data Centre, Cambridge, UK.
23. Discovery Studio 2.0, Accelrys Inc., San. Diego, CA, CA 92121.
24. Maurya, R.; Akanksha, Jayendra; Singh, A. B.; Srivatava, A. K. Bioorg. Med. Chem.
Lett. 2008, 18, 6534.
Time (min)
Figure 4. Blood glucose levels in STZ-induced diabetic rats before and up to 24 h
after administration of vehicle, compound 4a, 4i, 5b, 6 and metformin.