Efficient synthesis of piperazine-2,6-dione and 4-(1H-indole-2-carbonyl) piperazine-2,6-dione derivatives and their evaluation for anticancer activity

Article abstract of DOI:10.1007/s00044-012-0438-7

Condensation of iminodiacetic acid 1 with various amines i.e., cyclohexanamine, 1-(3-aminopropyl)imidazole, pyridin-2-ylmethanamine, pyridin-3-ylmethanamine, pyridin-4-ylmethanamine, 2-morpholinoethanamine, thiophen-2-ylmethanamine, 2-(thiophen-2-yl)ethanamine, furan-2-ylmethanamine, 2-(pyrrolidin-1-yl)ethanamine, and 1-(3-aminopropyl) pyrrolidin-2-one 2a-k under microwave irradiation gave the corresponding piperazine-2,6-dione derivatives 3a-k in quantitative yields. Piperazine-2,6-dione derivatives 3a-k on condensation with 1H-indole-2-carboxylic acid under microwave irradiation gave the corresponding 4-(1H-indole-2-carbonyl)piperazine-2,6-dione derivatives 4a-k in quantitative yields. All the synthesized compounds (3a-k & 4a-k) were purified by crystallization and characterized by spectroscopic means. On screening at a concentration of 10 μM, compounds 3k, 4e, 4i breast (T47D), 4j lung (NCI H-522), 3i colon (HCT-15), 4e ovary (PA-1), and 4g liver (HepG-2) exhibited good anticancer activity.

Full text of DOI:10.1007/s00044-012-0438-7

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2013) 22:4600–4609
DOI 10.1007/s00044-012-0438-7
ORIGINAL RESEARCH
Efficient synthesis of piperazine-2,6-dione and 4-(1H-indole-2-
carbonyl)piperazine-2,6-dione derivatives and their evaluation
for anticancer activity
•
•
•
Sandeep Kumar Nikhil Kumar Partha Roy
Sham M. Sondhi
Received: 23 June 2012 / Accepted: 18 December 2012 / Published online: 16 January 2013
Ó Springer Science+Business Media New York 2013
Abstract Condensation of iminodiacetic acid 1 with vari-
ous amines i.e., cyclohexanamine, 1-(3-aminopropyl)imid-
azole, pyridin-2-ylmethanamine, pyridin-3-ylmethanamine,
pyridin-4-ylmethanamine, 2-morpholinoethanamine, thiophen-
2-ylmethanamine, 2-(thiophen-2-yl)ethanamine, furan-2-ylme-
thanamine, 2-(pyrrolidin-1-yl)ethanamine, and 1-(3-aminopro-
pyl) pyrrolidin-2-one 2a–k under microwave irradiation gave
the corresponding piperazine-2,6-dione derivatives 3a–k in
quantitative yields. Piperazine-2,6-dione derivatives 3a–k on
condensation with 1H-indole-2-carboxylic acid under micro-
wave irradiation gave the corresponding 4-(1H-indole-2-car-
bonyl)piperazine-2,6-dione derivatives 4a–k in quantitative
yields. All the synthesized compounds (3a–k & 4a–k) were
purified by crystallization and characterized by spectroscopic
means. On screening at a concentration of 10 lM, compounds
3k, 4e, 4i breast (T47D), 4j lung (NCI H-522), 3i colon
(HCT-15), 4e ovary (PA-1), and 4g liver (HepG-2) exhibited
good anticancer activity.
and have attracted attention of the researchers working in the
area of medicinal chemistry (Poster et al., 1981; Toshiharu
et al., 1990; Folkes et al., 2001; Ong et al., 2003; Martins and
Carvalho, 2007). Diketopiperazine derivatives exhibiting
antitumor (Boger et al., 2000, Loughlin et al., 2000), antiviral
(Sinha et al., 2004), antifungal (Houston et al., 2004;
Tuntiwachwuttikul et al., 2008), antibacterial (Jhaumeer-
Laulloo et al., 2003; Abraham, 2005), antiaggregatory (Pons
et al., 1998), antileishmanial (Hazra et al., 2007), and anti-
inflammatory (Shvedaite et al., 1999) activities are well doc-
umented in literature. Diketopiperazine derivatives also act as
plasminogen activator inhibitor-1 (PAI-1) (Bryans et al.,
1996), thrombin inhibitor (Cody et al., 1999) and topoiso-
merase-II inhibitors (Grauslundet al.,2007).Besides,theseare
knowntoexhibitphototoxicactivity(Molesworthetal.,2010).
In search of potent antitumor molecules we have syn-
thesized and evaluated several molecules containing
thiazoline, N-substituted cyclic imides, benzimidazole,
acridine, amidine & bis amidine, and pyrimidine moieties
(Sondhi et al., 2009a, b, 2010a, b, 2011, 2012). In view of
the literature cited above, references cited therein, and our
background in this area it was considered worthwhile to
synthesize diketopiperazine derivatives using iminodiace-
tic acid and heterocyclic amines under microwave irradi-
ation followed by evaluation of their antitumor activity. To
the best of our knowledge all the derivatives synthesized
and reported in this paper are unknown in literature.
Keywords Microwave synthesis Á
Piperazine dione derivatives Á Anticancer activity
Introduction
Diketopiperazine derivatives form an important class of
heterocyclic compounds due to their biological activities
S. Kumar Á S. M. Sondhi (&)
Results and discussion
Department of Chemistry, Indian Institute of Technology-
Roorkee, Roorkee 247667, Uttrakhand, India
e-mail: sondifcy@iitr.ernet.in
Chemistry
N. Kumar Á P. Roy
Iminodiacetic acid (1; Scheme 1) and cyclohexanamine
(2a; Scheme 1) were mixed in equimolar proportion and
Department of Biotechnology, Indian Institute of Technology-
Roorkee, Roorkee 247667, Uttrakhand, India
123

Med Chem Res (2013) 22:4600–4609
4601
then subjected to microwave irradiation at 85 °C for 3 min.
TLC of reaction mixture showed completion of reaction.
Crude product, so obtained, was purified by crystallization
from methanol to get 1-cyclohexyl-piperazine-2,6-dione
(3a; Scheme 1) in 89 % yield.
1-Cyclohexyl-piperazine-2,6-dione (3a; Scheme 1) and
1H-indole-2-carboxylic acid were mixed in equimolar
proportion and subjected to microwave irradiation at
150 °C for 7 min. TLC of the reaction mixture showed
absence of the starting materials. Crude product so
obtained was purified by crystallization from methanol to
get pure product 1-cyclohexyl-4-(1H-indole-2-carbonyl)-
piperazine-2,6-dione (4a; Scheme 1) in 86 % yield.
In another experiment the above reaction mixture was
subjected to microwave irradiation for 3 min at a power level
of 300 W. TLC of reaction mixture showed that the reaction is
complete. Crude product, so obtained, was crystallized from
methanol to get pure product 3a in 87 % yield. Yields of
product 3a obtained by the above two methods are compara-
ble. Structure of compound 3a i.e., 1-cyclohexyl-piperazine-
In another experiment the above reaction mixture was
subjected to microwave irradiation at a power level of
850 W for 4 min. TLC of the reaction mixture showed
absence of the starting materials. Crude product so
obtained was purified by crystallization from methanol to
get pure product 4a in 82 % yield. Yields of product 4a
obtained from the above two methods are comparable.
Structure assigned to 1-cyclohexyl-4-(1H-indole-2-car-
bonyl)-piperazine-2,6-dione (4a; Scheme 1) is fully sup-
1
2,6-dione is fully supported by the correct spectral (IR, H
NMR, 13C NMR, GC–MS) and elemental analysis data
reported in the experimental section. Similarly, condensation
of 1-(3-aminopropyl)imidazole, pyridin-2-ylmethanamine,
pyridin-3-ylmethanamine, pyridin-4-ylmethanamine, 2-mor-
pholinoethanamine, thiophen-2-ylmethanamine, 2-(thiophen-
2-yl)ethanamine, furan-2-ylmethanamine, 2-(pyrrolidin-1-yl)
ethanamine, and 1-(3-aminopropyl) pyrrolidin-2-one (2b–k;
Scheme 1) with iminodiacetic acid (1; Scheme 1) gave
the corresponding piperazine-2,6-dione derivatives 3b–k
(Scheme 1) in quantitative yields. Physical constants, spectral
andelemental analysis data ofcompounds3b–k reportedin the
experimental section are in agreement with the structures
assigned to them.
1
ported by correct spectral data (IR, H NMR, 13C NMR,
GC–MS) and elemental analysis. Similarly condensation of
piperazine-2,6-dione derivatives 3b–k (Scheme 1) with
1H-indole-2-carboxylic acid gave the corresponding
4-(1H-indole-2-carbonyl)piperazine-2,6-dione derivatives
4b–k (Scheme 1) in quantitative yields. Physical constants,
spectral and elemental analysis data of 4b–k reported in the
experimental section fully support the structures assigned
to them.
Scheme 1 Synthesis of
piperazine-2,6-dione 3a–k
and 4-(1H-indole-2-
carbonyl)piperazine-2,6-dione
4a–k derivatives
O
COOH
MWI
+
H2N R1
2a-k
HN
3a-k
N R1
O
HN
COOH
COOH
1
N
MWI
H
O
O
C
N
N R1
O
N
H
4a-k
R1 is same for 2a-k, 3a-k & 4a-k
H2
C
S
a
b
c
d
e
f
R1=
R1=
R1=
R1=
R1=
R1=
g
h
i
R1=
R1=
R1=
R1=
R1=
S
N
CH2CH2
N CH2CH2CH2
H2
C
H2
C
O
N
H2
C
N
CH2CH2
j
N
O
H2
C
k
N
O
N
CH2CH2CH2
N CH2CH2
123

4602
Med Chem Res (2013) 22:4600–4609
Antitumor activity
chromatograph where built-in MS detector was used. Ele-
mental analysis was carried out on a Vario EL III ele-
mentor. Thin layer chromatography (TLC) was performed
on silica gel G for TLC (Merck) and spots were visualized
by iodine vapor or by irradiation with ultraviolet light
(254 nm). Compounds 3a–k and 4a–k were purified by
crystallization from methanol.
Purified and fully characterized compounds i.e., pipera-
zine-2,6-dione 3a–k (Scheme 1) and 4-(1H-indole-2-car-
bonyl)piperazine-2,6-dione derivatives 4a–k (Scheme 1)
were screened in vitro for anticancer activity (Skehan et al.,
1990; Monks et al., 1991) against five human cancer cell
lines consisting of breast (T47D), lung (NCl H-522), colon
(HCT-15), ovary (PA-1), and liver (HepG-2). Percentage
(%) growth inhibition of compounds 3a–k and 4a–k
against various cancer cell lines was determined at a con-
centration of 1 9 10-5 M solution and results are sum-
marized in Table 1. Compounds 3k, 4e, 4i breast (T47D),
4j lung (NCl H-522), 3j colon (HCT-15), 4e ovary (PA-1),
and 4g liver (HepG-2) exhibited good anticancer activity as
compared to standard drugs i.e., 5-fluorouracil, cyclo-
phosphamide, and cycloheximide.
General procedure for synthesis of piperazine-2,6-dione
derivatives 3a–k
Synthesis of 1-cyclohexylpiperazine-2,6-dione (3a)
(i) Iminodiacetic acid 1 (0.133 g; 1 mmol) and cyclo-
hexanamine (0.100 g; 1 mmol) were mixed thor-
oughly to form a homogeneous mixture. This mixture
was subjected to microwave irradiation at 85 °C for
3 min. TLC of the reaction mixture on silica gel using
ethyl acetate/methanol (1:1) as mobile phase showed
the absence of starting materials. Crude product so
obtained was purified by crystallization from metha-
nol to get pure product 3a in quantitative yield.
Anticancer activity of two series of compounds i.e.,
piperazine-2,6-dione 3a–k and 4-(1H-indole-2-car-
bonyl)piperazine-2,6-dione 4a–k derivatives is reported in
Table 1. From the activity data it is clear that 4-(1H-indole-2-
carbonyl)piperazine-2,6-dione derivatives 4e, 4g, 4i & 4j
prepared from the corresponding piperazine-2,6-dione
derivatives 3e, 3g, 3i & 3j are useful in increasing the anti-
cancer activity of 4e (breast T47D, ovary PA-1), 4g (liver
HepG-2), 4i (breast T47D), and 4j (lung NCl H-522). Good
anticancer activity shown by some of these molecules may be
due to the fact that these molecules met the electronic and
other stereochemical requirements on the target site in a better
way as compared to other molecules which failed to act.
(ii) Above experiment was also performed by irradiating
homogeneous mixture at a power level of 300 W for
3 min. Completion of the reaction was checked by
TLC on silica gel using ethyl acetate/methanol (1:1)
as mobile phase. Crude product so obtained was
purified by crystallization from methanol to get pure
product 3a in quantitative yield. Yields of product 3a
obtained by method (i) and (ii) are comparable.
Yield-85 %, mp: 118 °C: IR (KBr) vmax 3,146 (NH) 1,669
([C=O) cm-1. 1H NMR (500 MHz, D2O) d: 3.529 (s, 4H,
29 CH2), 3.024–3.031 (m, 1H, [CH–N–), 1.859–1.873 (d,
2H, J = 7 Hz, CH2), 1.679–1.693 (t, 2H, J = 7 Hz, CH2),
Conclusion
Several new piperazine-2,6-dione 3a–k and 4-(1H-indole-2-
carbonyl)piperazine-2,6-dione 4a–k derivatives have been
synthesized in high yields using microwave irradiation
technique. These compounds were screened for anticancer
activity against five human cancer cell lines. Compounds 4e,
4g, 4i, 4j, 3j & 3k exhibited good anticancer activity.
1.520–1.546 (d, 1H, J = 13 Hz, one
H of CH2),
1.194–1.270 (m, 4H, 29 CH2), 1.039–1.070 (m, 1H, one H
of CH2), 13C NMR (125 MHz, D2O) d: 171.1, 50.1, 48.8,
30.2, 24.1 and 23.6. GC–MS: m/z 197 (M??1, 10 %), 196
O
?
(M , 50 %), 113 (
+
, 30 %), 83 (
NH
, 22 %), 18
+
N
O
Experimental
. +
Microwave reactor model CEM DISCOVER model No
908010 and microwave oven model M197DL (Samsung)
were used for microwave irradiation. Melting points (mp)
were determined on a JSGW apparatus and are uncor-
rected. IR spectra were recorded using a Perkin Elmer 1600
(
, 100 %). Anal. calcd for C10H16N2O2: C 61.20, H
H2O
8.22, N 14.27; Found C 61.47, H 8.18, N 14.35.
Similarly, compounds 3b–k were synthesized.
1
FT spectrometer. H and 13C NMR spectra were recorded
1-(3-Imidazol-1-yl-propyl)-piperazine-2,6-dione (3b)
on a Bruker WH-500 spectrometer in a ca 5–15 % (w/v)
solution in deuterated solvent (TMS as internal standard).
GCMS was recorded on a Perkin Elmer Clarus 500 gas
Yield-91 %, mp: 114 °C: IR (KBr) vmax 3,470 (NH), 1,674
([C=O) cm-1. 1H NMR (500 MHz, D2O) d: 7.628 (s, 1H,
123

Med Chem Res (2013) 22:4600–4609
4603
Table 1 In vitro anticancer activity of piperazine-2,6-dione 3a–k and 4-(1H-indole-2-carbonyl)piperazine-2,6-dione 4a–k derivatives
Compd. no
Anticancer activity (% growth inhibition at a concentration of 1 9 10-5 M*
Breast T47D
Lung NCI H-522
Colon HCT-15
Ovary PA-1
Liver HepG-2
3a
15
08
16
08
04
01
08
16
04
01
21
07
00
20
12
21
16
06
09
21
16
14
15
26
11
11
08
08
04
08
09
15
21
07
00
21
06
00
19
04
05
08
00
14
15
31
08
24
11
15
07
32
01
20
33
04
04
25
30
49
19
30
07
02
14
38
07
15
04
24
17
27
19
12
16
24
23
17
20
27
37
18
15
26
26
25
40
17
23
13
42
18
24
11
23
29
08
22
12
34
38
13
31
21
25
38
29
24
21
18
40
25
34
34
17
20
03
45
19
36
30
11
18
18
26
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
5-FUa
CYC-PHOb
CYC-HEXIc
Bold values represent compounds showing good anticancer activity
* Compounds tested in triplicate, data expressed as mean value of three independent experiments
a
5-FU 5-Fluorouracil
b
CYC-PHO Cyclophosphamide
c
CYC-HEXI Cycloheximide
Ar), 7.050 (s, 1H, Ar), 6.909 (s, 1H, Ar), 3.983–4.010
(t, 2H, J = 6.5 Hz, CH2), 3.461 (s, 4H, 29 CH2),
2.781–2.813 (t, 2H, J = 7.5 Hz, CH2), 2.011–2.140 (m,
2H, CH2), 13C NMR (125 MHz, D2O) d: 171.3, 137.5, 127.3,
120.0, 48.9, 43.9, 36.5 and 28.0. GC–MS: m/z 223 (M??1,
5 %), 222 (M?, 30 %). Anal. calcd for C10H14N4O2: C
54.04, H 6.35, N 25.21; Found C 54.13, H 6.30, N 25.27.
149.1, 138.5, 124.1, 123.2, 48.9 and 43.2. GC–MS: m/z 206
O
?
(M ?1, 5 %), 205 (M , 50 %), 113 (
?
+
, 22 %), 78
NH
N
O
+
(
, 25 %). Anal. calcd for C10H11N3O2: C 58.53, H
N
5.40, N 20.48; Found C 58.69, H 5.47, N 20.54.
1-(Pyridin-3-ylmethyl)piperazine-2,6-dione (3d)
Yield-92 %, mp: 128 °C: IR (KBr) vmax 3,500 (NH) 1,682
1-(Pyridin-2-ylmethyl)piperazine-2,6-dione (3c)
Yield-94 %, mp: 142 °C: IR (KBr) vmax 3,500 (NH) 1,673
1
([C=O), 1,473(Ar) cm-1. H NMR (500 MHz, D2O) d:
1
([C=O), 1,474 (Ar) cm-1. H NMR (500 MHz, D2O) d:
8.450–8.460 (d, 1H, J = 5 Hz, Ar), 7.779–7.798 (m, 1H,
Ar), 7.377–7.393 (d, 1H, J = 8 Hz, Ar), 7.329–7.354 (q,
1H, J = 5 Hz & 7 Hz, Ar), 4.215 (s, 2H, CH2), 3.524 (s,
4H, 29 CH2), 13C NMR (125 MHz, D2O) d: 171.2, 151.4,
8.457 (s, 1H, Ar), 8.425–8.432 (d, 1H, J = 3.5 Hz, Ar),
7.812–7.827 (d, 1H, J = 7.5 Hz, Ar), 7.382–7.406 (t, 1H,
Ar), 4.092 (s, 2H, CH2), 3.502 (s, 4H, 29 CH2), 13C NMR
123

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Med Chem Res (2013) 22:4600–4609
1-(2-Thiophen-2-yl-ethyl)-piperazine-2,6-dione (3h)
Yield-87 %, mp: 136 °C: IR (KBr) vmax 3,450 (NH),
(125 MHz, D2O) d: 171.2, 151.2, 149.9, 135.5, 134.1,
123.2, 48.1 and 43.0. GC–MS: m/z 206 (M??1, 6 %), 205
O
O
N
O
1,669, 1,647 ([C=O), 1,613 (Ar) cm-1
.
1H NMR
+
(M?, 65 %), 127 (H2C N NH, 4 %), 113 (
NH
,
+
(500 MHz, D2O) d: 7.257–7.267 (d, 1H, J = 5 Hz, Ar),
6.916–6.946 (m, 2H, Ar), 3.521(s, 4H, 29 CH2),
3.180–3.206 (t, 2H, J = 6.5 Hz, CH2), 3.113–3.139 (t,
2H, J = 6.5 Hz, CH2), 13C NMR (125 MHz, D2O) d:
171.5, 138.5, 127.5, 126.6, 125.3, 48.9, 40.7 and 26.9.
O
+
24 %), 78 (
, 25 %). Anal. calcd for C10H11N3O2: C
N
58.53, H 5.40, N 20.48; Found C 58.71, H 5.45, N 20.55.
GC–MS: m/z 225 (M??1, 9 %), 224 (M?, 50 %), 113
1-(Pyridin-4-ylmethyl)piperazine-2,6-dione (3e)
O
S
+
(
N
NH, 30 %), 83(
, 20 %). Anal. calcd for
+
Yield-90 %, mp: 133 °C: IR (KBr) vmax 3,500(NH),
1,662([C= O), 1,474 (Ar) cm-1 1H NMR (500 MHz,
.
O
D2O) d: 8.464 (s, 2H, Ar), 7.370 (s, 2H, Ar), 4.116 (s, 2H,
CH2), 3.533 (s, 4H, 29 CH2), 13C NMR (125 MHz, D2O)
d: 171.2, 149.9, 143.3, 123.2, 48.1 and 43.0. GC–MS:
m/z 206 (M??1, 6 %), 205 (M?, 53 %), 127
C10H12N2O2S: C 53.55, H 5.39,N 12.49, S 14.30; Found
C 53.51, H 5.41, N 12.54, S 14.36.
1-Furan-2-ylmethyl-piperazine-2,6-dione (3i)
O
N
O
O
+
Yield-96 %, mp: 122 °C: IR (KBr) vmax 3,420 (NH), 1,652
+
(
H2C N
NH,5 %), 113 (
, 22 %), 78 (
,
+
NH
N
([C=O), 1,593 (Ar) cm-1 1H NMR (500 MHz, D2O)
.
O
d: 7.424–7.425 (d, 1H, J = 0.5 Hz, Ar), 6.403–6.409
(d, 1H, J = 3 Hz, Ar), 6.331–6.337 (t, 1H, Ar), 4.070
(s, 2H, CH2), 3.478 (s, 4H, 29 CH2), 13C NMR (125 MHz,
D2O) d: 171.0, 146.1, 144.2, 110.8, 110.7, 48.9 and 35.5.
GC–MS: m/z 195 (M??1, 8 %), 194 (M?, 50 %), 113
O
20 %). Anal. calcd for C10H11N3O2: C 58.53, H 5.40, N
20.48; Found C 58.69, H 5.44, N 20.57.
1-(2-Morpholinoethyl)piperazine-2,6-dione (3f)
Yield-93 %, mp: 123 °C: IR (KBr) vmax 3,500(NH),
1,686([C=O) cm-1
.
1H NMR (500 MHz, D2O)
+
(
N
NH, 25 %). Anal. calcd for C9H10N2O3: C 55.67, H
d: 3.641–3.659 (t, 4H, J = 4.5 Hz, 29 CH2), 3.522 (s, 4H,
29 CH2), 3.052 (t, 2H, J = 5 Hz, CH2), 2.624 (t, 2H,
J = 5 Hz, CH2), 2.509 (s, 4H, 29 CH2), 13C NMR
(125 MHz, D2O) d: 171.3, 66.0, 54.1, 52.4, 48.9 and 35.5.
GC–MS: m/z 228 (M??1, 8 %), 227 (M?, 45 %), 18
O
5.19, N 14.43; Found C 55.75, H 5.23, N 14.37.
1-(2-Pyrrolidin-1-yl-ethyl)-piperazine-2,6-dione (3j)
Yield-89 %, mp: 117 °C: IR (KBr) vmax 3,440(NH), 1,678
([C=O) cm-1. 1H NMR (500 MHz, D2O) d: 3.493 (s, 4H,
29 CH2), 3.003–3.072 (m, 8H, 49 CH2), 1.859(s, 4H,
29 CH2), 13C NMR (125 MHz, D2O) d: 171.4, 55.9, 53.7,
48.9, 36.5 and 22.5. GC–MS: m/z 212 (M??1, 5 %), 211
O
. +
(
, 100 %). Anal. calcd for C10H17N3O3: C 52.85,
H2O
H 7.54, N 18.49; Found C 52.78, H 7.59, N 18.60.
1-Thiophen-2-ylmethyl-piperazine-2,6-dione (3g)
?
(M , 30 %), 113 (
+
; 25 %). Anal. calcd for
NH
N
Yield-87 %, mp: 130 °C: IR (KBr) vmax 3,427(NH),
1,651([C=O), 1,464 (Ar)cm-1. 1H NMR(500 MHz, D2O)d:
7.348–7.361 (t, 1H, J = 3 Hz, Ar), 7.076 (s, 1H, Ar),
6.934–6.954(q, 1H, J = 2 Hz & 5 Hz, Ar), 4.230–4.236 (d,
2H, J = 3 Hz, CH2), 3.454–3.468 (q, 4H, J = 4 Hz, 5 Hz,
29 CH2,), 13C NMR (125 MHz, D2O) d: 171.3, 134.0, 129.3,
127.7, 127.6, 48.9 and 37.3. GC–MS: m/z 211 (M??1, 6 %),
O
O
C10H17N3O2: C 56.85, H 8.11, N 19.89; Found C 56.96,
H 8.14, N 19.76.
1-[3-(2-Oxo-pyrrolidin-1-yl)-propyl]-piperazine-2,
6-dione (3k)
Yield-94 %, mp: 109 °C: IR (KBr) vmax 3,432 (NH), 1,668,
S
?
210 (M , 35 %), 113 (
+
, 25 %), 83 (
NH
, 20 %).
+
N
1
1,626 ([C=O) cm-1. H NMR (500 MHz, D2O) d: 3.550
O
(s, 4H, 29 CH2), 3.384–3.413 (t, 2H, J = 7 Hz, 29 CH2),
3.246–3.273 (t, 2H, J = 6.5 Hz, CH2), 2.854–2.884 (t, 2H,
J = 7.5 Hz, CH2), 2.316–2.349(t, 2H, J = 8.5 Hz, CH2),
Anal. calcd for C9H10N2O2S: C 51.41, H 4.79, N 13.32, S
15.25; Found C 51.47, H 4.82, N 13.38, S 15.31.
123

Med Chem Res (2013) 22:4600–4609
4605
1.928–1.958 (t, 2H, J = 7.5 Hz, CH2), 1.806–1.835 (t, 2H,
J = 7.5 Hz, CH2), 13C NMR (125 MHz, D2O) d: 178.7,
171.1, 48.8, 47.9, 39.4, 36.8, 30.8, 24.4 and 18.2. GC–MS:
O
. +
18 %), 83 (
, 30 %), 82 (
+
, 12 %). Anal.
calcd for C19H21N3O3: C 67.24, H 6.24, N 12.38; Found
C 67.11, H 6.31, N 12.44.
Similarly compounds 4b–k were synthesized.
?
m/z 240 (M ?1, 5 %), 239 (M , 35 %), 113 (
?
+
N
O
NH
,
1-(3-(1H-imidazol-1-yl)propyl)-4-(1H-indole-2-carbonyl)-
O
O
piperazine-2,6-dione (4b)
. +
CH3
. +
NH
25 %), 99 (
, 17 %), 85 (
, 17 %). Anal.
N
Yield-86 %, mp: [300 °C: IR (KBr) vmax 3,470 (NH),
calcd for C11H17N3O3: C 55.22, H 7.16, N 17.56; Found C
55.29, H 7.11, N 17.63.
1,694, 1,635 ([C=O), 1,515 (Ar) cm-1
.
1H NMR
(500 MHz, MeOD) d: 7.813 (s, 1H, Ar), 7.593–7.609 (d,
1H, J = 8 Hz, Ar), 7.434–7.450 (d, 1H, J = 8 Hz Ar),
7.188–7.235 (m, 2H, Ar), 7.040–7.085 (m, 3H, Ar),
4.079–4.159 (t, 2H, J = 7 Hz, CH2), 3.582 (s, 4H,
29 C2), 2.900–2.930 (t, 2H, J = 7.5 Hz, CH2),
2.130–2.188 (m, 2H, CH2), 13C NMR (125 MHz, MeOD)
d: 171.4, 168.6, 138.3, 138.3, 133.8, 129.2, 128.6, 124.7,
122.7, 120.8, 120.8, 113.0, 106.9, 50.4, 45.2, 37.9 and
General procedure for synthesis of 4-(1H-indole-2-
carbonyl)piperazine-2,6-dione derivatives 4a–k
Synthesis of 1-cyclohexyl-4-(1H-indole-2-
carbonyl)piperazine-2,6-dione (4a)
(i) Cyclohexylpiperazine-2,6-dione 3a (0.196 g; 1 mmol)
and 1H-indole-2-carboxylic acid (0.161 g; 1 mmol)
were mixed thoroughly to form a homogeneous mix-
ture. This reaction mixture was subjected to micro-
wave irradiation at 150 °C for 7 min. TLC of the
reaction mixture on silica gel using ethyl acetate/
methanol (1:1) as mobile phase showed absence of
starting materials. Crude product so obtained was
crystallized from methanol to get pure product 4a in
quantitative yield.
30.0. GC–MS: m/z 366 (M??1, 5 %), 365 (M?, 20 %),
O
H
+
O
C
N
H2
N
N C CH
284
(
,
11 %),
271
2
O
.
.
O
H3C N
O
O
O
O
+
+
(
, 8 %), 257 (HN
, 20 %),
N C
N C
N
N
H
H
O
O
O
N
221 (
N (CH2)3
N
O
N+, 6 %), 113 (HN N+, 20 %),
(ii) The above experiment was also performed by irradi-
ating the homogeneous mixture for 4 min at a power
level of 850 W. Completion of the reaction was
checked by TLC on silica gel using ethyl acetate/
methanol (1:1) as mobile phase. Crude product so
obtained was crystallized from methanol to get pure
product 4a in quantitative yield. Yields of product 4a
obtained by method (i) and (ii) are comparable.
O
H
. +
N CH3
HN
N
. +
N
85 (
, 6 %), 84 (
, 32 %), 82 (
,
N
O
+
O
N
O
.
+
+
N
N
12 %), 70 (
, 40 %), 69 (
,57 %).
O
Anal. calcd for C19H19N5O3: C 62.46, H 5.24, N 19.17;
Found C 62.62, H 5.19, N 19.35.
Yield-80 %, mp: 280 °C: IR (KBr) vmax 3,403 (NH),
1,702 ([C=O), 1,519 (Ar) cm-1 1H NMR (500 MHz,
.
MeOD) d: 7.614–7.631 (d, 1H, J = 8.5 Hz, Ar),
7.441–7.459 (d, 1H, J = 8.5 Hz, Ar), 7.216–7.249 (dt,
1H, J = 1 & 8 Hz, Ar), 7.108 (s, 1H, Ar), 7.046–7.077
(m, 1H, Ar), 3.575 (s, 4H, 29 CH2), 3.031–3.074 (m, 1H,
CH), 2.003–2.018 (m, 2H, CH2), 1.798–1.845 (m, 2H,
CH2), 1.677–1.706 (dd, 1H, J = 1.5 Hz & 13.5 Hz, one H
of CH2), 1.312–1.404 (m, 4H, 29 CH2), 1.221–1.246 (q,
1H, J = 3.5 Hz & 9 Hz, one H of CH2), 13C NMR
(125 MHz, MeOD) d: 171.2, 166.9, 138.6, 131.7, 128.9,
125.2, 122.9, 120.9, 113.1, 108.0, 51.5, 50.4, 31.9, 25.9
and 25.4. GC–MS: m/z 340 (M??1, 5 %), 339 (M?,
4-(1H-indole-2-carbonyl)-1-pyridin-2-ylmethy
lpiperazine-2,6-dione (4c)
Yield-88 %, mp: [300 °C: IR (KBr) vmax 3,470 (NH),
1,692 ([C=O), 1,528 (Ar) cm-1 1H NMR (500 MHz,
.
MeOD) d: 8.622–8.632 (d, 1H, J = 5 Hz, Ar), 7.827–7.862
(m, 1H, Ar), 7.617–7.634 (d, 1H, J = 8.5 Hz, Ar),
7.440–7.458 (dd, 2H, J = 1 Hz & 8.5 Hz Ar), 7.375–7.400
(m, 1H, Ar), 7.223–7.256 (m, 1H, Ar), 7.118–7.120 (d, 1H,
J = 1 Hz), 7.067–7.083 (m, 1H, Ar), 4.289 (s, 2H, CH2),
3.511(s, 4H,29 CH2), 13C NMR (125 MHz, MeOD) d:
171.1, 166.4, 153.8, 150.5, 138.7, 138.6, 130.9, 128.9,
125.3, 124.7, 123.5, 122.9, 121.0, 113.1, 108.4, 50.4 and
44.1. GC–MS: m/z 349 (M??1, 7 %), 348 (M?, 35 %),
O
, 15 %), 113 (HN
O
O
HN
O
.
+
O
N C
35 %), 257 (
N+
,
N
H
123

4606
Med Chem Res (2013) 22:4600–4609
O
3.522 (s, 4H, 29 CH2), 3.038–3.066 (t, 2H, J = 7 Hz, CH2),
2.610–2.638 (t, 2H, J = 7 Hz, CH2), 2.509 (s, 4H, 29 CH2),
13C NMR (125 MHz, DMSO?D2O) d: 171.7, 167.3, 138.6,
131.7, 128.9, 125.2, 122.9, 121.0, 113.1, 108.0, 55.1, 53.2,
50.3, 37.4 and 24.1. GC–MS: m/z 371 (M??1, 10 %), 370
O
+
N
204 (
N
, 50 %). Anal. calcd for C19H16N4O3: C
N
O
65.51, H 4.63, N 16.08; Found C 65.69, H 4.70, N 16.31.
O
4-(1H-indole-2-carbonyl)-1-pyridin-3-ylmethyl
+
(M?, 50 %), 284 (H2CH2C N
N C
, 11 %), 271
piperazine-2,6-dione (4d)
N
H
O
Yield-82 %, mp: 276 °C: IR (KBr) vmax 3,444 (NH), 1,691,
.
O
O
HN
O
.
O
1,624 ([C=O), 1,511 (Ar) cm-1 1H NMR (500 MHz,
.
O
+
+
(
C N N CH3, 11 %), 257 (
,
N C
N
DMSO?D2O) d: 8.267–8.270 (d, 1H, J = 1.5 Hz, Ar),
8.133–8.140 (d, 1H, J = 3.5 Hz, Ar), 7.507–7.522 (d, 1H,
J = 7.5 Hz, Ar), 7.166–7.182 (d, 1H, J = 8.0 Hz, Ar),
7.021–7.041 (m, 2H, Ar), 6.719–6.749 (t, 1H, J = 7.5 Hz,
Ar), 6.589–6.619 (t, 1H, J = 7.5 Hz, Ar), 6.358 (s, 1H, Ar),
3.917 (s, 2H, CH2), 3.590 (s, 4H, 29 CH2), 13C NMR
(125 MHz, DMSO?D2O) d: 172.1, 166.4, 149.1, 148.5,
136.5, 136.3, 135.6, 133.4, 127.5, 123.7, 122.2, 120.9,
118.9, 111.9, 103.2, 48.9 and 40.7. GC–MS: m/z 349
N
H
H
O
+
16 %), 85 (
. , 5 %), 84 (
N
, 35 %). Anal. calcd
O
O
N
+
for C19H22N4O4: C 61.61, H 5.99, N, 15.13; Found C 61.79,
H 5.88, N 15.32.
4-(1H-indole-2-carbonyl)-1-(thiophen-2-
ylmethyl)piperazine-2,6-dione (4g)
O
+
Yield-85 %, mp:[300 °C: IR (KBr) vmax 3,390 (NH),
1,683([C=O), 1,476, (Ar) cm-1. 1H NMR (500 MHz, D2O) d:
7.615–7.632 (d, 1H, J = 8.5 Hz, Ar), 7.443–7.460 (d, 1H,
J = 8.5 Hz, Ar), 7.257–7.267 (d, 1H, J = 5 Hz Ar),
7.217–7.248 (dt, 1H, J = 1 Hz & 7.5 Hz, Ar), 7.108 (s, 1H,
Ar), 7.046–7.077 (t, 1H, J = 7.5 Hz, Ar), 6.918–6.988(m, 2H,
Ar), 4.182 (s, 2H, CH2), 3.524 (s, 4H, 29 CH2), 13C NMR
(125 MHz,MeOD)d:171.2, 166.7, 138.7, 134.1, 131.3, 129.3,
128.9, 127.7, 127.6, 125.2, 122.9, 120.9, 113.1, 108.2, 48.1 and
40.9. GC–MS: m/z 354 (M??1, 10 %), 353 (M?, 78 %), 257
N
(M??1, 6 %), 348 (M?, 30 %), 204 (
N
N
,
O
30 %). Anal. calcd for C19H16N4O3: C 65.51, H 4.63, N
16.08; Found C 65.72, H 4.57, N 16.27.
4-(1H-indole-2-carbonyl)-1-pyridin-4-ylmethyl
piperazine-2,6-dione (4e)
Yield-86 %, mp: [300 °C: IR (KBr) vmax 3,452 (NH),
1,684, 1,624 ([C=O), 1,515 (Ar) cm-1
.
1H NMR
.
O
N
O
O
HN
O
O
C
+
H2
C
S
+
(500 MHz, DMSO?D2O) d: 8.534–8.545 (d, 2H,
J = 5 Hz, Ar), 7.549–7.372 (m, 4H, Ar), 7.090–7.120 (t,
1H, J = 7.5 Hz, Ar), 6.955–6.985 (t, 1H, J = 7.5 Hz, Ar),
6.750 (s, 1H, Ar), 3.982 (s, 2H, CH2), 3.505 (s, 4H,
29 CH2), 13C NMR (125 MHz, DMSO?D2O) d: 171.9,
166.7, 149.2, 145.6, 135.8, 135.6, 127.4, 123.1, 122.4,
121.1, 119.1, 111.9, 103.5, 48.1, 41.7. GC–MS: m/z 349
N
, 8 %),
(
N
, 25 %), 209 (
N
H
O
.
H
+
N
HN
N+
, 25 %), 85
145 (
, 10 %), 113 (
CHO
O
H
N
+
N
HN
. +
(
O
, 7 %), 84 (
, 32 %), 70 (
, 40 %), 69
N
O
O
+
+
O
N
N
N
(M??1, 5 %), 348 (M?, 50 %), 204 (
N
,
.
N
+
O
(
, 100 %), Anal. calcd for C18H15N3O3S; C 61.18, H
O
4.28, N 11.89; Found C 61.39, H 4.21, N 12.07.
40 %). Anal. calcd for C19H16N4O3: C 65.51, H 4.63,
N 16.08; Found C 65.69, H 4.69, N 16.01.
4-(1H-indole-2-carbonyl)-1-(2-(thiophen-2-
4-(1H-indole-2-carbonyl)-1-2-morpholinoethy
yl)ethyl)piperazine-2,6-dione (4h)
lpiperazine-2,6-dione (4f)
Yield-87 %, mp: [300 °C: IR (KBr) vmax 3,403 (NH), 1,701
([C=O), 1,615 (Ar) cm-1. 1H NMR (500 MHz, MeOD) d:
7.614–7.631 (d, 1H, J = 8.5 Hz, Ar), 7.441–7.459 (d, 1H,
J = 8.5 Hz, Ar), 7.257–7.267 (d, 1H, J = 5 Hz, Ar),
7.216–7.249 (dt, 1H, J = 1 Hz & 8 Hz, Ar), 7.108 (s, 1H,
Ar), 7.046–7.077 (t, 1H, J = 7.5 Hz, Ar), 6.917–6.947 (m,
Yield-81 %, mp: [300 °C: IR (KBr) vmax 3,426 (NH), 1,706
1
([C=O), 1,594 & 1,523 (Ar) cm-1. H NMR (500 MHz,
MeOD) d: 7.615–7.632 (d, 1H, J = 8.5 Hz, Ar), 7.442–
7.460 (d, 1H, J = 9 Hz, Ar), 7.217–7.250 (dt, 1H, J = 1 &
7.5 Hz, Ar), 7.107(s, 1H, Ar), 7.045–7.076 (t, 1H,
J = 7.5 Hz, Ar), 3.641–3.659 (t, 4H, J = 4.5 Hz, 29 CH2),
123

Med Chem Res (2013) 22:4600–4609
4607
2H, Ar), 3.522 (s, 4H, 29 CH2), 3.181–3.207 (t, 2H,
J = 6.5 Hz, CH2), 3.114–3.140 (t, 2H, J = 6.5 Hz, CH2),
13C NMR (125 MHz, DMSO?D2O) d: 171.2, 166.7, 138.7,
134.1, 131.3, 129.3, 128.9, 127.7, 127.6, 125.2, 122.9, 120.9,
MeOD) d: 7.626–7.643 (d, 1H, J = 8.5 Hz, Ar),
7.449–7.467 (dd, 1H, J = 1 Hz & 8.5 Hz, Ar), 7.233–7.266
(m, 1H, Ar), 7.138–7.139 (d, 1H, J = 0.5 Hz Ar),
7.058–7.090 (dt, 1H, 1 Hz & 8.5 Hz, Ar), 3.711–3.730 (t,
4H, J = 5 Hz, 29 CH2), 3.601 (s, 4H, 29 CH2),
3.064–3.088 (q, 2H, J = 6 Hz & 7 Hz, CH2), 2.628–2.652
(t, 2H, J = 6 Hz, CH2), 2.528 (s, 4H, 29 CH2), 13C NMR
(125 MHz, MeOD) d: 171.2, 166.1, 138.8, 130.5, 128.9,
125.5, 123.0, 121.1, 113.2, 108.6, 67.7, 56.0, 54.4, 50.3 and
36.9. GC–MS: m/z 355 (M??1, 7 %), 354 (M?, 25 %), 284
113.1, 108.2, 48.1, 40.7 and 26.9. GC–MS: m/z 368 (M??1,
O
O
C N
+
10 %), 367 (M?, 55 %), 284 (
2, 12 %),
NCH CH
2
N
H
O
O
.
.
O
H3C N
O
O
N C
O
N C
+
+
HN
271 (
, 11 %), 257 (
,
O
O
N
H
N
H
+
O
O
C
O
N
C N
NCH CH
(
2, 10 %), 256 ( +
,
2
N
HN
O
N
O
H
H2
C
O
O
S
+
O
HN
N+
, 18 %),
H2C N
O
N
16 %), 223 (
, 5 %), 113 (
N
+
O
N
N
O
12 %), 210 (
+, 50 %), 84 ( N CH , 100 %), 71
2
. +
S
84 (
, 32 %). Anal. calcd for C19H17N3O3S: C 62.11, H
. +
.
+
+
(
, 25 %), 70 (
N
, 55 %), 69 (
, 87 %).
N
NH
4.66, N 11.44; Found C 62.28, H 4.71, N 11.35.
Anal. calcd for C19H22N4O3: C 64.39, H 6.26, N 15.81;
Found C 64.51, H 6.32, N 15.97.
1-(Furan-2-ylmethyl)-4-(1H-indole-2-carbonyl)-
piperazine-2,6-dione (4i)
4-(1H-indole-2-carbonyl)-1-[3-(2-oxopyrrolidin-1-yl)-
propyl]-piperazine-2,6-dione (4k)
Yield-87 %, mp: 281 °C: IR (KBr) vmax 3,450 (NH), 1,692
([C=O), 1,536 (Ar) cm-1. 1H NMR (500 MHz, MeOD) d:
7.596–7.632 (m, 2H, Ar), 7.439–7.458 (dd, 1H, J = 1 Hz
& 8.5 Hz, Ar), 7.221–7.252 (m, 1H, Ar), 7.109–7.110 (d,
1H, J = 0.5 Hz, Ar), 7.048–7.080 (m, 1H, Ar),
6.554–6.561 (d, 1H, J = 3.5 Hz, Ar), 6.468–6.479 (q, 1H,
J = 2 & 3.5 Hz, Ar), 4.183 (s, 2H, CH2), 3.568 (s, 4H,
29 CH2), 13C NMR (125 MHz, MeOD) d: 171.2, 166.7,
148.3, 145.3, 138.7, 131.3, 128.9, 125.2, 122.9, 120.9,
113.1, 111.9, 111.7, 108.2, 50.4 and 36.8. GC–MS: m/z 338
Yield-83 %, mp: [300 °C: IR (KBr) vmax 3,426 (NH), 1,702
([C=O), 1,591 & 1,532 (Ar) cm-1. H NMR (500 MHz,
1
MeOD) d: 7.624–7.640 (d, 1H, J = 8 Hz, Ar), 7.447–7.465
(dd, 1H, J = 1 Hz & 8.5 Hz, Ar), 7.229–7.261 (dt, 1H,
J = 0.5 Hz & 7.0 Hz Ar), 7.127 (s, 1H, Ar), 7.056-7.086 (m,
1H, Ar), 3.583 (s, 4H, 29 CH2), 3.448–3.477 (t, 2H, 7.5 Hz,
Ar), 3.369–3.396 (t, 2H, J = 7 Hz, CH2), 2.911–2.941 (t, 2H,
J = 7.5 Hz, CH2), 2.387–2.419 (t, 2H, J = 8 Hz, CH2),
2.057–2.072 (m, 2H, CH2), 1.888–1.917 (m, 2H, CH2), 13
C
O
.
+
O
NMR (125 MHz, MeOD) d: 209.8, 178.6, 171.2, 138.7,
128.9, 125.4, 122.9, 121.1, 113.1, 108.4, 54.6, 50.3, 40.4,
38.0, 31.8, 26.2and18.8. GC–MS:m/z383(M??1,7 %), 382
?
(M ?1, 8 %), 337(M , 30 %), 257 (
?
HN
O
N C
,
N
H
O
O
O
.
+
O
N C
H2
O
?
(M , 25 %), 299 (
H CH CH C N
, 5 %), 284
16 %), 193 (
C
N
O
N+, 30 %), 113 (HN N+, 18 %),
3
2
2
N
H
O
O
O
O
. +
.
O
N
O
+
N
N
HN
O
+
N C
O , 75 %), 70 (
,
H2
+
85 (
, 6 %), 84 (
N
(
H2C C
N
N C
, 10 %), 271 (H3C
,
,
,
N
+
O
O
H
N
N
H
H
O
58 %), 69
N
.
O
+
.
(
, 70 %). Anal. calcd for C18H15N3O4: C 64.09,
O
O
+
+
C N
NH
O
10 %), 257 (
, 22 %), 126 (
O
N CH2CH2CH2
N
H
H 4.48, N 12.46; Found C 64.34, H 4.55, N 12.34.
O
H
HN
N
. +
, 5 %), 84(
4-(1H-indole-2-carbonyl)-1-(2-pyrrolidin-1-yl-ethyl)-
HN
N+
5 %), 113(
, 18 %), 85(
N
+
O
O
N
piperazine-2,6-dione (4j)
O
.
+
+
N
N
Yield-83 %, mp: 276 °C: IR (KBr) vmax 3,450 (NH), 1,691,
60 %), 70 (
, 58 %), 69 (
,70 %), Anal. calcd for
1,624 ([C=O), 1,541 (Ar) cm-1 1H NMR (500 MHz,
.
O
O
123

4608
Med Chem Res (2013) 22:4600–4609
discussion. Mr. Sandeep Kumar is thankful to MHRD, New Delhi for
financial assistance.
C20H22N4O4: C 62.82, H 5.80, N 14.65; Found C 62.98, H
5.87, N 14.49.
Pharmacology
References
In vitro cytotoxicity against human cancer cell lines (Skehan
et al., 1990; Monks et al., 1991) The human cancer cell lines
procured from the National Cancer Institute, Frederick, U.
S. A. were used in this study. Cells were grown in tissue
culture flasks in complete growth medium (RPMI-1640
medium with 2 mM glutamine, pH 7.4 supplemented with
10 % fetal bovine serum, 100 lg/mL streptomycin, and 100
units/mL penicillin) in a carbon dioxide incubator (37 °C,
5 % CO2, 90 % RH). The cells at a sub confluent stage were
harvested from the flask by treatment with trypsin (0.05 % in
PBS (pH 7.4) containing 0.02 % EDTA). Cells with viability
of more than 98 %, as determined by trypan blue exclusion,
were used for determination of cytotoxicity. The cell sus-
pension of 1 9 105 cells/mL was prepared in complete
growth medium. Stock 4 9 10-2 M compound solutions
were prepared in DMSO. The stock solutions were serially
diluted with complete growth medium containing 50 lg/mL
of gentamycin to obtain working test solution of required
concentrations.
Abraham WR (2005) Controlling pathogenic gram-negative bacteria
by interfering with their biofilm formation. Drug Des Rev 2:
13–33
Boger DL, Fink BE, Hedrick MP (2000) A new class of highly
cytotoxic diketopiperazines. Bioorg Med Chem Lett 10:
1019–1020
Bryans J, Charlton P, Chicarelli-Robinson I, Collins M, Faint R,
Latham C, Shaw I, Trew S (1996) Inhibition of plasminogen
activator inhibitor-1 activity by two diketopiperazines, XR330
and XR334 produced by streptomyces sp. J Antibiot 49:
1014–1021
Cody WL, Augelli-Szafran CE, Berryman KA, Cai C, Doherty AM,
Edmunds JJ, He JX, Narasimhan LS, Penvose-Yi J, Plummer JS,
Rapundalo ST, Rubin JR, Van Huis CA, Leblond L, Winocour
PD, Siddiqui MA (1999) The design of potent and selective
inhibitors of thrombin utilizing a piperazinedione template: part
2. Bioorg Med Chem Lett 9:2503–2508
Folkes A, Roe MB, Sohal S, Golec J, Faint R, Brooks T, Charlton P
a series of
(2001) Synthesis and in vitro evaluation of
diketopiperazine inhibitors of plasminogen activator inhibitor-
1. Bioorg Med Chem Lett 11:2589–2592
Grauslund M, Thougaard AV, Fuchtbauer A, Hofland KF, Hjorth PH,
Jensen PB, Sehested M, Fuchtbauer EM, Jensen LH (2007) A
mouse model for studying the interaction of bisdioxopiperazines
with topoisomerase IIa in vivo. Mol Pharmacol 72:1003–1014
Hazra A, Paira P, Palit P, Banerjee S, Mondal NB, Sahu NP (2007)
Synthesis of symmetrically 1,4-disubstituted piperazine-2,5-
diones: a new class of antileishmanial agents. J Chem Res 2007:
381–383
Houston DR, Synstad B, Eijsink VGH, Stark MJR, Eggleston IM,
Van ADMF (2004) Structure-based exploration of cyclic dipep-
tide chitinase Inhibitors. J Med Chem 47:5713–5720
Jhaumeer-Laulloo S, Khodabocus A, Jugoo A, Jheengut D, Sobha S
(2003) Synthesis of diketopiperazines containing prolinyl unit-
cyclo(L-prolinyl-L-leucine), cyclo(L-prolinyl-L-isoleucine) and
cyclo(L-tryptophyl-L-proline). J Indian Chem Soc 80:765–768
Loughlin WA, Marshall RL, Carreiro A, Elson KE (2000) Solution-
phase combinatorial synthesis and evaluation of piperazine-2,5-
dione derivatives. Bioorg Med Chem Lett 10:91–94
Martins MB, Carvalho I (2007) Diketopiperazines: biological activity
and synthesis. Tetrahedron 63:9923–9932
Molesworth PP, Gardiner MG, Jones RC, Smith JA, Tegg RS, Wilson
C (2010) Synthesis and phytotoxicity of structural analogues of
thaxtomin natural products. Aust J Chem 63:813–820
Monks A, Scudiero D, Skehan P, Shoemaker R, Paull K, Vistica D,
Hose C, Langley J, Cronise P (1991) Feasibility of a high–flux
anticancer drug screen using a diverse panel of cultured human
tumor cell lines. J Natl Cancer Inst 83:757–766
Ong CW, Chang YA, Jing-Yun Wu, Chien-Chung Cheng (2003)
Novel design of a pentacyclic scaffold as structural mimic of
saframycin A. Tetrahedron 59:8245–8249
In vitro cytotoxicity against various human cancer cell
lines was determined (Monks et al., 1991) using 96-well
tissue culture plates. The 100 lL of cell suspension was
added to each well of the 96-well tissue culture plates. The
cells were allowed to grow in CO2 incubator (37 °C, 5 %
CO2, 90 % RH) for 24 h. The test materials in complete
growth medium (100 lL) were added after 24 h incubation
to wells containing cell suspension. The plates were further
incubated for 48 h (37 °C in an atmosphere of 5 % CO2
and 90 % relative humidity) in a carbon dioxide incubator
after addition of test material and then the cell growth was
stopped by gently layering trichloroacetic acid (50 % TCA,
50 lL) on top of the medium in all the wells. The plates
were incubated at 4 °C for 1 h to fix the cells attached to
the bottom of the wells. The liquid of all the wells was
gently pipetted out and discarded. The plates were washed
five times with distilled water to remove TCA, growth
medium low molecular weight metabolites, serum proteins
etc. were air dried. Cell growth was measured by staining
with sulforhodamine B dye (Skehan et al., 1990). The
adsorbed dye was dissolved in Tris–HCl Buffer (100 lL,
0.01 M, pH 10.4) and plates were gently stirred for 10 min
using a mechanical stirrer. The optical density (OD) was
recorded on ELISA reader at 540 nm.
Pons JF, Fauchere JL, Lamaty F, Molla A, Lazaro R (1998) A
constrained diketopiperazine as a new scaffold for the synthesis
of peptidomimetics. Eur J Org Chem 5:853–859
Poster DS, Penta JS, Bruno S, MacDonald JS (1981) ICRF-187 in
clinical oncology. Cancer Clin Trials 4:143–146
Shvedaite IP, Udrenaite EB, Lauzhikene NA, Gaidyalis PG (1999)
Synthesis and anti-inflammatory activity of 4-acyl and 4-sulfonyl
derivatives of piperazine-2,6-dione. Pharm Chem J 33:313–316
Acknowledgments We are thankful to the technical staff of the
Chemistry Department, I. I. T. Roorkee, for spectroscopic studies and
elemental analysis and also to Head I. I. C. for providing NMR
facility. Special thanks are due to Prof. G. Bhattacharjee and Prof.
Ravi Bhushan of Chemistry Department, I. I. T. Roorkee, for helpful
123

Med Chem Res (2013) 22:4600–4609
4609
Sinha S, Srivastava R, De Clercq E, Singh RK (2004) Synthesis and
antiviral properties of arabino and ribonucleosides of 1,3-
dideazaadenine, 4-nitro-1, 3-dideazaadenine and diketopipera-
zine. Nucleosides Nucleotides Nucleic Acids 23:1815–1824
Skehan P, Storeng R, Scudiero D, Monks A, McMahon J, Vistica D,
Warren JT, Bokesch H, Kenney S, Boyd MR (1990) New
colorimetric cytotoxicity assay for anticancer-drug screening.
J Natl Cancer Inst 82:1107–1112
Sondhi SM, Singh J, Rani R, Gupta PP, Agarwal SK, Saxena AK
(2010b) Synthesis, anti- inflammatory and anticancer activity
evaluation of some novel acridine derivatives. Eur J Med Chem
45:555–563
Sondhi SM, Rani R, Roy P, Agrawal SK, Saxena AK (2011)
Synthesis, anti-inflammatory, and anticancer activity evaluation
of some heterocyclic amidine and bis-amidine derivatives.
J Heterocycl Chem 48:921–926
Sondhi SM, Rani R, Gupta PP, Agrawal SK, Saxena AK (2009a)
Synthesis, anticancer, and anti-inflammatory activity evaluation
of methanesulfonamide and amidine derivatives of 3,4-diaryl-2-
imino-4-thiazolines. Mol Divers 13:357–366
Sondhi SM, Singh J, Agrawal SK, Saxena AK, Roy P (2012)
Synthesis of pyrimidine and condensed pyrimidine derivatives
and their evaluation for anti-inflammatory activity. Med Chem
Res 21:91–99
Sondhi SM, Rani R, Roy P, Agrawal SK, Saxena AK (2009b)
Microwave-assisted synthesis of N-substituted cyclic imides and
their evaluation for anticancer and anti-inflammatory activities.
Bioorg Med Chem Lett 19:1534–1538
Toshiharu N, Shinichi Y, Toshihiko K, Muneaki T, Akira H, Makoto
I, Shigeru T (1990) Antitumor activity of MST-16, a novel
derivative of bis(2,6-dioxopiperazine), in murine tumor models.
Cancer Chemother Pharmacol 26:193–197
Sondhi SM, Rani R, Singh J, Roy P, Agarwal SK, Saxena AK (2010a)
Solvent free synthesis, anti-inflammatory and anticancer activity
evaluation of tricyclic and tetracyclic benzimidazole derivatives.
Bioorg Med Chem Lett 20:2306–2310
Tuntiwachwuttikul P, Taechowisan T, Wanbanjob A, Thadaniti S,
Taylor WC (2008) Lansai A-D, secondary metabolites from
Streptomyces sp. SUC1. Tetrahedron 64:7583–7586
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