Design, synthesis and molecular docking of novel structural hybrids of substituted isatin based pyrazoline and thiadiazoline as antitumor agents

Article abstract of DOI:10.1007/s00044-017-1781-5

Cancer, which is considered to be the world’s most serious illness cause 8.2 million deaths and this rate may double by 2030. We herein report a new series of 3-(2-(p-substituted)-2-((5-phenyl-1,3,4-thiadiazol-2-yl)imino)-2-(p-substituted)ethylidene)indolin-2-one (15–19) and 5-substituted-5′-substituted phenyl-2′,4′-dihydrospiro[indoline-3,3′-pyrazol]-2-one derivatives (20–24) as potent anticancer agents. These compounds were evaluated for in vitro antitumor activity against the National Cancer Institute panel of 60 cancer cell lines. Among all the synthesized compounds, two compounds 15 and 16 showed remarkable antitumor activity with GI₅₀ (MG-MID) values of 0.65 & 0.72 μM, respectively against Non-small cell lung cancer. To gain insight for mode of binding with Epidermal Growth Factor Receptor kinase enzyme, these compounds were further subjected to docking studies.

Full text of DOI:10.1007/s00044-017-1781-5

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-017-1781-5
ORIGINAL RESEARCH
Design, synthesis and molecular docking of novel structural
hybrids of substituted isatin based pyrazoline and thiadiazoline
as antitumor agents
1,2
Gouthami Thumma3 Sarangapani Manda4
●
●
●
Kiran Gangarapu
Anvesh Jallapally2 Ravi Jarapula4 Sriram Rekulapally4
●
●
Received: 17 April 2016 / Accepted: 3 January 2017
© Springer Science+Business Media New York 2017
Abstract Cancer, which is considered to be the world’s
most serious illness cause 8.2 million deaths and this rate
may double by 2030. We herein report a new series of 3-(2-
(p-substituted)-2-((5-phenyl-1,3,4-thiadiazol-2-yl)imino)-2-
(p-substituted)ethylidene)indolin-2-one (15–19) and 5-sub-
stituted-5′-substituted phenyl-2′,4′-dihydrospiro[indoline-
3,3′-pyrazol]-2-one derivatives (20–24) as potent anticancer
agents. These compounds were evaluated for in vitro anti-
tumor activity against the National Cancer Institute panel of
60 cancer cell lines. Among all the synthesized compounds,
two compounds 15 and 16 showed remarkable antitumor
activity with GI50 (MG-MID) values of 0.65 & 0.72 µM,
respectively against Non-small cell lung cancer. To gain
insight for mode of binding with Epidermal Growth Factor
Receptor kinase enzyme, these compounds were further
subjected to docking studies.
Introduction
Cancer, a life-threatening disease is the second common
cause of death after cardiovascular diseases (Jemal et al.
2011). The American Chemical Society defines cancer as a
group of diseases characterized by uncontrolled growth, and
the spread of abnormal cells that left untreated may lead to
death (Garcia et al. 2007). According to WHO global cancer
report 2014, it is expected to increase 57% worldwide in
next 20 years (Vineis and Wild 2014). By 2030, it is pro-
jected that there will be ∼26 million new cancer cases and
17 million cancer deaths per year (Thun et al. 2010; Boyle
and Levin 2008). The projected increase will be driven
largely by growth and aging of populations and will be
largest in low-resource and medium-resource countries
(Abraham 2014).
Isatins are endogenous molecules present in human and
mammals which exhibits diverse pharmacological profiles
especially antimicrobial (Thadhaney et al. 2010; Bari
et al. 2015), antitumor (Havrylyuk et al. 2012; Liang et al.
2014; Havrylyuk et al. 2015; Thi Lan Huong et al. 2015;
Lesyk et al. 2015), antiviral (Varma and Khan 2014),
anti-inflammatory (Socca et al. 2014), and antioxidant
activities (Dandia et al. 2014). The isatin moiety present
in wide range of compounds can act as inhibitors of
apoptosis (Medvedev et al. 2007) targeting proteases
(Zhou et al. 2006), caspases (Chapman et al. 2002)
kinases (Cao et al. 2009) extracellular signal regulated
protein kinase (ERK) (Cane et al. 2000). Isatin hybrids
possessing heterocyclic analogues have been identified as
potential antitumor agents and the most promising hybrid
molecules are shown in Fig. 1 (Ibrahim et al. 2015;
Eldehna et al. 2015; Ribeiro et al. 2016; Monteiro et al.
2014; Fares et al. 2015).
●
Keywords EGFR kinase enzyme Non-small cell lung
●
●
●
cancer Molecular docking Antitumor activity NCI
* Kiran Gangarapu
gangakiran1905@gmail.com
1
Department of Pharmacy, Anurag Group of Institutions,
Venkatapur (V), Ghatkesar (M), Medchal District, Hyderabad,
Telangana 500 088, India
2
Dr. Macs Bio-Pharma Pvt Ltd, JNTUH Kukatpally, Hyderabad-
85, Telangana, India
3
Department of Pharmaceutics, SVS School of Pharmacy,
Ramaram, Hanamkonda, Warangal, Telangana 506 009, India
4
Department of Pharmaceutical Chemistry, University College of
Pharmaceutical Sciences, Kakatiya University, Warangal 506 009,
India

Med Chem Res
Fig. 1 Anticancer isatin hybrid
molecules
In recent days, chemists have gained considerable
attention on five membered aromatic systems having three
heteroatoms at the symmetrical positions (i.e., pyrazolines,
and thiadiazolines) due to their interesting biological
activities (Yusuf and Jain 2014; Shih et al. 2015; Altıntop
et al. 2015). On the other hand, various thiadiazole (Bur-
savich et al. 2007; Nikalje et al. 2015) and pyrazoline
derivatives (Havrylyuk et al. 2012; Karthikeyan et al. 2015)
as a potential chemotherapeutic agents. Spirooxindole were
reported as an important class of heterocyclic scaffolds with
promising anticancer activity (Reddy et al. 2015; Ziarani
et al. 2016). Pyrazoline derivatives, are nitrogen hetero-
cyclic compounds with electron rich property (Schmidt and
Dreger 2011), widely occur in nature in the form of alka-
loids (Shaaban et al. 2012), vitamins, pigments, and as
constituents of plant and animal cell (Singh et al. 2009; Fall
et al. 2002). Thiadiazole acts as “hydrogen binding domain”
and “two electron donor system” with a constrained phar-
macophore, has structural frameworks similar to several
naturally occurring alkaloids that show a wide range of
pharmaceutical and industrial importance (Chen et al.
2012).
Experimental
General methods
Melting points (°C) were determined on Toshniwal melting
point apparatus and are uncorrected. Elemental analyses
were performed on a Perkin-Elmer 240 elemental analyzer.
Reactions were monitored using thin layer chromatography
(TLC) on aluminum-backed precoated silica gel 60 F254
plates (E Merck). The FT-IR spectra of the compounds were
recorded on thermo Nicolet Nexus 670S series.1H NMR
and 13C NMR were recorded on a Avance-300 MHz
instrument using TMS as an internal standard (chemical
shifts in δ, ppm). Mass spectra were recorded on LC-MSD-
Trap-SL using ESI(+) method. Column chromatography
was performed by using Qualigen’s silica gel for column
chromatography (60–120 mesh). All the fine chemicals and
reagents used were purchased from Sigma-Aldrich (St.
Louis, USA).
Synthesis of 2-amino-5-aryl-1,3,4-thiadiazole (1–3)
In the present study, we herein report the synthesis of 3-
(2-(p-substituted)-2-((5-phenyl-1,3,4-thiadiazol-2-yl)
imino)-2-(p-substituted)ethylidene)indolin-2-one (15–19)
and 5-substituted-5′-substituted phenyl-2′,4′-dihydrospiro
[indoline-3,3′-pyrazol]-2-one derivatives (20–24) (Fig. 2).
The new compounds were screened for their in vitro anti-
tumor activity using the NCI’s disease-oriented human cell
lines assay. Docking simulations were performed using the
X-ray crystallographic structure of the EGFR in complex
with an inhibitor to explore the binding modes of these
compounds at the active site.
Compounds 1–3 were synthesized from substituted ben-
zaldehyde and thiosemicarbazide and subsequently cyclized
with bromine in glacial acetic acid. The solids were
obtained and the residue was recrystallized from suitable
solvent.
General procedure for the synthesis of isatin chalcones
(11–14)
To a solid homogenous mixture of substituted isatin (4–6)
(1 mmol) and acetophenones (7–10) (1 mmol) with catalytic

Med Chem Res
Fig. 2 Design strategy
amount of dimethylamine was taken in 250 mL conical
flask and stirred for 15–30 min. The reaction mixture was
cooled overnight, a colorless solid was formed. Twenty
milliliter of glacial acetic acid and five drops of con-
centrated HCl was added to this precipitate and the mixture
was warmed at 80 °C for 30 min and after dehydration, gave
isatin chalcones (11–14).
128.9 (4C), 128.0 (2C), 126.4 (2C), 122.9 (2C), 120.6,
110.2. ESI-MS m/z: 409.1 [M+H]+; Anal. Calcd. for
C24H16N4OS: C, 70.57; H, 3.95; N, 13.72; found: C, 70.59;
H, 3.98; N, 13.71.
3-(2-((5-(4-Chlorophenyl)-1,3,4-thiadiazol-2-yl)imino)-2-
phenylethylidene)indolin-2-one (16)
General procedure for synthesis of various imines
derivatives (15–19)
Yield 80%; m.p. 189–190 °C; IR (KBr) ṽ max cm−1: 3477
(NH str), 3106 (C=CH, str), 1681 (C=O), 1655 (C=N),
1385 (C=C), 1320 (Ar–C=N), 1015 (Ar–C–S), 735 (para-
Cl). 1H NMR (300 MHz, DMSO-d6) δ 9.13 (s, 1H), 8.89 (s,
J = 7.2, 1H), 8.34–8.26 (m, 4H), 7.89–7.83 (M, 5H), 7.43
(t, J = 6.4, 1H), 7.22 (t, J = 7.2, 1H), 7.09 (d, J = 7.6, 1H),
6.18 (s, 1H). 13C NMR (75 MHz, DMSO-d6) δ 190.6, 178.8
(2C), 168.3, 163.9, 144.1, 139.3, 138.6, 136.3 (2C), 135.8,
133.3 (2C), 133.1 (2C), 132.4 (3C), 131.6, 126.5, 125.4,
122.8, 120.9, 110.8. ESI-MS m/z: 443.3 [M+H]+; Anal.
Calcd. for C24H15ClN4OS: C, 65.08; H, 3.41; N, 12.65;
found: C, 65.11; H, 3.48; N, 12.60.
A mixture of 2-Amino-5-aryl-1, 3, 4-thiadiazole (1–3)
(2 mmol) and substituted isatin chalcones (11–14) (2 mmol)
was taken in 20 mL of absolute ethanol in 250 mL conical
flask. The resulting mixture was refluxed for 5–8 h and the
reaction mixture was cooled on overnight and solvent was
evaporated under reduced conditions, the residue thus
obtained was recrystallized from methanol gave imine
derivatives (15–19).
3-(2-Phenyl-2-((5-phenyl-1,3,4-thiadiazol-2-yl)imino)
ethylidene)indolin-2-one (15)
3-(2-Phenyl-2-((5-(p-tolyl)-1,3,4-thiadiazol-2-yl)imino)
ethylidene) indolin-2-one (17)
Yield 83%; m.p. 190–191 °C; IR (KBr) ṽ max cm−1: 3426
(NH str), 3161 (C=CH, str), 1681 (C=O), 1650(C=N),
1458 (Ar–C=C), 1385(Ar–C=N), 1015 (Ar–C–S),.1H
NMR (300 MHz, DMSO-d6) δ 9.96 (s, 1H), 8.93 (s, J = 6.8,
1H), 8.32–8.25 (m, 4H), 7.93–7.81 (m, 6H), 7.41 (t, J =
7.2, 1H), 7.23 (t, J = 7.2, 1H), 7.06 (d, J = 8.4, 1H), 6.21(s,
1H). 13C NMR (75 MHz, DMSO-d6) δ 191.0, 179.2 (2C),
169.3, 164.8, 143.2, 137.5, 136.6, 133.8 (2C), 132.7 (2C),
Yield 78%; m.p. 186–187 °C; IR (KBr) ṽ max cm−1: 3458
(NH str), 3106 (C=CH, str),2996 (C–H, str), 1681 (C=O),
1660 (C=N), 1446 (C=C), 1355 (Ar–C=N), 972
(Ar–C–S). 1H NMR (300 MHz, DMSO-d6) δ 10.09 (s, 1H),
8.84 (d, J = 7.5 Hz, 1H), 8.29–7.83 (m, 7H), 7.53–7.49 (m,
3H), 7.39 (t, J = 7.6 Hz, 1H), 7.13 (d, J = 7.2 Hz, 1H), 5.99
(s, 1H), 2.48 (s, 3H). 13C NMR (75 MHz, DMSO-d6)

Med Chem Res
δ 188.3, 177.4, 168.9 (2C), 162.3, 138.8 (2C), 137.8, 137.1,
136.2, 133.6 (2C), 133.3 (2C), 131.6 (2C), 130.3, 129.5
(2C), 126.8, 125.3, 122.1, 120.3, 110.5, 21.6. ESI-MS m/z:
423.3 [M+H]+; Anal. Calcd. for C25H18N4OS:C, 71.07; H,
4.29; N, 13.26; found: C, 71.15; H, 4.32; N, 13.29.
5′-Phenyl-2′,4′-dihydrospiro[indol-3,3′-pyrazol]-2-one (20)
Yield 84%; m.p. 200–201 °C; IR (KBr) ṽ max cm−1: 3481
1
(NH str), 3422 (NH str), 1709 (C=O), 1600 (C=N). H
NMR (300 MHz, DMSO-d6) δ 9.16 (s, 1H), 8.09 (s, J = 7.2
Hz, 1H), 7.63 (d, J = 7.2 Hz, 2H), 7.56–7.51 (m, 3H),
7.22–7.16 (m, 2H), 6.92 (t, J = 7.6 Hz, 1H), 6.20 (s, 1H),
3.43 (d, J = 15.0 Hz, 1H), 3.72 (d, J = 15.0 Hz, 1H). 13C
NMR (75 MHz, DMSO- d6) δ 180.3, 151.3, 140.1, 132.5,
130.9, 130.1, 129.3, 129.0, 128.3, 128.4, 127.6, 126.3,
122.4, 113.8, 70.3, 45.9. ESI-MS m/z: 264.1 [M+H]+;
Anal. Calcd. for C16H13N3O: C, 72.99; H, 4.98; N, 15.96;
found: C, 72.87; H, 5.02; N, 15.93.
3-(2-(4-Hydroxyphenyl)-2-(5-phenyl-1,3,4-thiadiazol-2-
ylimino)ethylidene)indolin-2-one (18)
Yield 80%; m.p. 182–183 °C; IR (KBr) ṽ max cm−1: 3456
(NH str), 3300 (OH, str), 3100 (C=CH, str), 1670 (C=N),
1
1385 (C=C), 1320 (Ar–C=N), 1015 (Ar–C–S), H NMR
(300 MHz, DMSO-d6) δ 9.98 (s, 1H), 8.89–8.86 (m, 3H),
8.39 (d, J = 6.8 Hz, 2H), 8.10–7.89 (m, 4H), 7.43 (t, J =
7.6 Hz, 1H), 7.16 (d, J = 7.6 Hz, 1H), 6.91 (d, J = 6.8 Hz,
2H), 6.01 (s, 1H), 5.39 (s, 1H). 13C NMR (75 MHz, DMSO-
d6) δ 191.5, 178.4, 169.1, 165.3, 163.9, 144.2, 138.9, 136.8
(2C), 136.2 (3C), 134.1 (2C), 132.5, 131.3, 127.2, 126.2,
125.1, 124.2, 120.6, 116.7 (2C), 110.8. ESI-MS m/z: 425[M
+H]. Anal. Calcd. for C24H16N4O2S.C, 67.91; H, 3.80; N,
13.20; found: C, 67.98; H, 3.86; N, 13.18.
5′-(4-Chlorophenyl)-2′,4′-dihydrospiro[indoline-3,3′-
pyrazol]-2-one (21)
Yield 71%; m.p. 222–223 °C; IR (KBr) ṽ max cm−1: 3461
(NH, str), 3279 (NH str), 1712 (C=O), 1609 (C=N). H
1
NMR (300 MHz, DMSO-d6) δ9.32 (s, 1H), 8.02 (s, J = 7.6
Hz, 1H), 7.64 (t, J = 6.8 Hz, 2H), 7.46 (d, J = 8.4 Hz, 2H),
7.26–7.21 (m, 2H), 6.97 (t, J = 7.6, 1H), 6.33 (s, 1H), 3.58
(d, J = 15.0 Hz, 1H), 3.43 (d, J = 15.0 Hz, 1H). 13C NMR
(75 MHz, DMSO- d6) δ 178.5, 147.5, 141.7, 133.9, 132.3
(2C), 129.7 (2C), 128.9, 127.8 (2C), 124.0, 122.8, 110.1,
70.1, 44.1.ESI-MS m/z: 298.5 [M+H]+; Anal. Calcd. for
C16H12ClN3O: C, 64.54; H, 4.06; N, 14.11; found: C,
64.47; H, 4.02; N, 14.02.
3-(2-((5-(4-Chlorophenyl)-1,3,4-thiadiazol-2-yl)imino)-2-
(4-hydroxyphenyl) ethylidene)indolin-2-one (19)
Yield 80%; m.p. 218–219 °C; IR (KBr) ṽ max cm−1: 3495
(NH str), 3350 (OH, str), 3110 (C=CH, str), 1685 (C=N),
1385 (C=C), 1365 (Ar–C=N), 926 (Ar–C–S), 735 (para-
Cl). 1H NMR (300 MHz, DMSO-d6) δ: 10.02 (s, 1H),
8.78–8.74 (m, 3H), 8.34(d, J = 7.2 Hz, 2H), 8.13–7.93 (m,
3H), 7.36 (t, J = 7.6 Hz, 1H), 7.09 (d, J = 7.2 Hz, 1H), 6.88
(d, J = 8.4 Hz, 2H), 6.03 (s, 1H), 5.36 (s, 1H). 13C NMR
(75 MHz, DMSO-d6) δ 189.3, 179.3 (2C), 170.8, 165.5,
154.3, 149.8, 138.9 (2C), 136.3, 134.6 (2C), 133.8 (2C),
132.6 (2C), 131.3, 128.4, 127.1, 126.2, 123.6, 121.4, 116.9,
111.2. ESI-MS m/z: 459.7 [M+H]+; Anal. Calcd. for
C24H15ClN4O2S: C, 62.81; H, 3.29; N, 12.21; found: C,
62.87; H, 3.31; N, 12.15.
1-Benzyl-5′-phenyl-2′,4′-dihydrospiro[indoline-3,3′-
pyrazol]-2-one (22)
Yield 71%; m.p. 232–235 °C; IR (KBr)ṽ max cm−1: 3476
(NHstr), 3276 (NH str), 1706 (C=O), 1603 (C=N). H
1
NMR (300 MHz, DMSO-d6) δ9.19 (s, 1H),7.71 (d, J = 7.2
Hz, 2H), 7.61–7.55 (m, 3H), 7.41–7.25 (m, 8H), 6.98 (d, J
= 6.8, 1H), 4.66 (s, 2H), 3.58 (d, J = 15.0 Hz, 1H), 3.46 (d,
J = 15.0 Hz, 1H). 13C NMR (75 MHz, DMSO-d6) δ 177.3,
147.8, 142.9, 141.8, 131.8, 131.6, 130.2, 129.9, 125.6 (2C),
125.3 (2C), 125.0 (2C), 124.7, 123.7(3C), 123.2, 116.4,
67.1, 54.6, 44.8.ESI-MS m/z: 354.3 [M+H]+; Anal. Calcd.
for C23H19N3O: C, 78.16; H, 5.42; N, 11.89; found: C,
78.12; H, 5.48; N, 11.87.
General procedure for the synthesis of 5-substituted-5′-
substituted phenyl-2′,4′-dihydrospiro[indoline-3,3′-
pyrazol]-2-one derivatives (20–24)
5-Bromo-5′-phenyl-2′,4′-dihydrospiro[indoline-3,3′-
pyrazol]-2-one (23)
A mixture of substituted isatin chalcones 11–14 (1 mmol)
and hydrazine hydrate (1 mmol) was taken in 30 mL of
absolute ethanol in 25 mL conical flask. Then the reaction
mixture was refluxed for about 1 h. Then the reaction
mixture was cooled on overnight and the precipitate was
collected by filtration. Thus, obtained spiro derivatives (20–
24) were purified by column chromatography and subse-
quently by recrystallization with absolute ethanol.
Yield 83%; m.p. 232–234 °C; FTIR (KBr) ṽ max cm−1
:
3462 (NH, str), 3278 (NH, str), 1707 (C=O), 1618 (C=N).
1H NMR (300 MHz, DMSO-d6), 9.12 (s, 1H), 8.11 (s, J =
7.5 Hz, 1H), 7.61 (d, J = 8.8 Hz, 2H), 7.53–7.47 (m, 3H),
7.21 (d, J = 7.6 Hz, 1H), 7.02 (d, J = 7.2 Hz, 1H), 6.89 (s,
1H), 3.43 (d, J = 15.0 Hz, 1H), 3.34 (d, J = 15.0 Hz, 1H).

Med Chem Res
13C NMR (75 MHz, DMSO-d6) δ 178.2, 147.6, 147.2,
131.8, 130.1, 128.9, 128.6, 127.1, 123.8 (2C), 123.1 (2C),
122.6, 120.8, 68.4, 43.4.ESI-MS m/z: 343.1 [M+H]+; Anal.
Calcd. for C16H12BrN3O.C, 56.16; H, 3.53; N, 12.28;
found: C, 56.20; H, 3.58; N, 12.20.
5′-(4-Methoxyphenyl)-2′,4′-dihydrospiro[indoline-3,3′-
pyrazol]-2-one (24)
Yield 83%; m.p. 232–234 °C; IR (KBr) ṽ max cm−1: 3438
(NH, str), 3391 (NH str), 1710 (C=O), 1617 (C=N) , 1301
1
(OCH3). H NMR (300 MHz, DMSO-d6) δ 8.02 (s, 1H),
7.64 (d, J = 8.8 Hz, 2H), 7.33 (d, J = 7.6 Hz, 1H), 7.28 (d,
J = 6.8 Hz, 1H), 7.05 (t, J = 7.6 Hz, 1H), 6.91 (t, J = 10.0
Hz, 3H), 6.02 (s, 1H), 3.84 (s, 3H), 3.72 (d, J = 15.0 Hz,
1H), 3.42 (d, J = 15.0 Hz, 1H). 13C NMR (75 MHz,
DMSO-d6) δ 178.7, 159.5, 147.4, 141.4, 132.3, 129.0,
127.1 (2C), 125.3, 123.5, 122.1, 114.0 (2C), 109.6, 69.5,
56.1, 43.9.ESI-MS m/z: 294.2 [M+H]+; Anal. Calcd. for
C17H15N3O2: C, 69.61; H, 5.15; N, 14.33; found: C, 69.68;
H, 5.12; N, 14.39.
Molecular docking studies
To gain more insight about the binding modes of synthe-
sized derivatives (15–24), we herein performed docking
studies (Rekulapally et al. 2015) on Epidermal Growth
Factor Receptor (EGFR). In this study, X-ray crystal
structure of human EGFR at resolution 1.9 Å (PDB ID:
4ICZ) was used further to identify binding modes involved
in the inhibition activity. The protein monomer was opti-
mized for geometry correction followed by energy optimi-
zation using Merck Molecular Force Field (MMFF). This
optimized receptor was used for docking simulation.
Molecular docking studies for synthesized analogues were
carried out using GRIP batch docking method available in
BioPredicta tools of VLife Molecular Design Suite
4.3 software. GRIP docking employees the PLP scoring
function for ligand receptor interactions (i.e., hydrogen
bonding, steric interactions, vanderwaal’s interactions,
hydrophobic interactions and electrostatic interactions) with
the active site of EGFR protein. The PLP scores were
compared with gefitinib (Pao et al. 2004), an EGFR inhi-
bitor used for breast, lung, and other cancers. The best
conformers and the dock score for each ligand was shown in
Table 1.
Antitumor activity
The cytotoxic activity of synthesized compounds was
evaluated at National Cancer Institute (NCI), Bethesda,
Maryland, USA in an in vitro 60 human tumor cell lines
panel. The human tumor cell line derived from nine

Med Chem Res
neoplastic cancer types i.e., leukemia, non-small cell lung,
prostate, melanoma, breast, colon, CNS, ovarian, and renal
cancers. In vitro cytotoxic assays were performed according
to the USA NCI protocol. The compounds were first eval-
uated at single dose primary anticancer assay towards 60
cancer lines (concentration 10−5 M). Compounds which
exhibit significant growth inhibition are evaluated against
the 60 cell panel at five concentration levels (Andreani et al.
2008; Grever et al. 1992; Shoemaker 2006; Alley et al.
1988).
The IR spectrum of compounds isatin-thiadiazole hybrids
(15–19) exhibited absorption bands in the range of
3200–3100 cm−1 due to -ene C–H stretching bonds,
1650–1500 cm−1 due to imine C=N stretching and
1
800–700 cm−1 due to aromatic deformation. The H NMR
peaks in the range of δ 8.93–6.88 ppm were due to different
aromatic protons. δ5.0–6.0 ppm was characteristic to =CH
protons; and around δ 9.0–11.0 ppm was assigned to –NH
proton of isatin. The 1H NMR spectrum of compounds 20–
24 exhibited two doublets (δ 3.42–3.84 ppm) due to –CH2
protons of pyrazoline ring and multiplets (δ 6.5–8.00 ppm)
for the aromatic protons. The singlet protons at around δ
9.16 and 6.20 are assigned for –NH proton of isatin and
pyrazoline, respectively.
Results and discussion
Chemistry
Molecular docking
As a starting point for the study, new derivatives were
synthesized from the intermediate isatin chalcones (11–14),
which were prepared by the reaction of acetophenones (7–
10) with isatin (4–6) in a solvent free condition using
dimethylamine by refluxing in glacial acetic acid and Conc
HCl. The compounds isatin-thiadiazole hybrids (15–19)
were synthesized from isatin chalcones (11–14) and 2-
amino-5-aryl-thiadiazoles (1–3). The 2-amino-5-aryl-thia-
diazole was synthesized from benzyladehyde and thiose-
micarbazide under reflux to give thiosemicarbazone and
subsequently cyclized with bromine in acetic acid. The
synthesis of spiro isatin-pyrazolines (20–24) was carried as
reported earlier in the literature (Mohammadizadeh 2006)
(Scheme 1)
The synthesized compounds 15–24 were docked with
4ICZ binding site of EGFR protein wherein some of the
compounds showed better docking score than the
standard drug gefitinib. Docking results showed that
compound 3-(2-phenyl-2-((5-phenyl-1,3,4-thiadiazol-2-yl)
imino)ethylidene) indolin-2-one (15) has highest dock score
of −79.11 with hydrogen bond and vanderwaals interac-
tions between protein and ligand. VLife Sciences 4.3 was
employed for the docking studies to explore the binding
mode of ligands. To validate the docking simulations,
gefitinib was used as the reference ligand. The original
ligand score obtained for gefitinib was −71.05, confirming
the ability of the method to accurately predict the binding
confirmation. All ligands exhibited negative docking scores
and were comparable with the reference gefitinib. From the
dock score, compounds 15, 16, 17, 18, 19, 21, and 22 were
found to have highest negative dock score ranging from
Derivatives obtained were fully characterized by FT-IR,
1H and 13C NMR and Mass (ESI) spectral data. All com-
pounds have shown an excellent agreement between cal-
culated and experimentally obtained data for CHN analysis.
R'
O
O
R'
R1
R1
(i)
O
+
O
(iii)
O
N
N
N
R2
R'
HN
R2
R1
7 : R' = H
8 : R' = OH
4: R1, R2 = H
5: R1 = Br; R2 =H
6: R1 = H, R2 = -CH2C6H5
O
11-14
N
R2
9 : R' = OCH3
10: R' = Cl
(ii)
1 - 3
20-24
N
N
R'
R
R
S
NH2
1-3
S
1 : R = H
2 : R = CH3
3 : R = Cl
N
R1
N
O
N
N
15-19
R2
Scheme 1 Synthesis of isatin based pyrazolines and thiadiazolines. Reaction conditions: (i) dimethylamine, glacial acetic acid, Conc HCl, reflux,
80 °C, 30 min; (ii) substituted 2-amino5-aryl thiadiazole (1–3), EtOH, reflux, 5–8 h, (iii) hydrazine hydrate, EtOH, reflux, 1 h

Med Chem Res
Fig. 3 3D interactions of ligands 15, 16, 22 and gefitinib showing hydrogen, charge, hydrophobic and vanderwaal’s interactions with EGFR
protein
−79.11 to −59.45 (Table 1). All the docked compounds
were analyzed for various types of interactions such as
hydrophobic bonding, charge, hydrogen, and vanderwaal’s
interactions. Figure 3 shows the docking of the ligands in
the receptor cavity. All the ligands and reference exhibited
same interactions such as hydrogen, charge, hydrophobic,
and vanderwaal’s interactions as shown in Table 1.
dtp.nci.nih.gov), Bethesda, MD, U.S.A. All the derivatives
were subjected to the NCI’s disease oriented human cell
lines screening assay for the evaluation of their in vitro
antitumor activity. The compounds were tested at a single-
dose concentration of 10 µM, and the percentage of growth
over the 60 tested cell lines were determined and illustrated
in (Table 2).
Among all, 3-(2-(p-substituted)-2-((5-phenyl-1,3,4-thia-
diazol-2-yl)imino)-2-(p-substituted)ethylidene)indolin-2-
one derivatives (15 and 16) and 5-substituted-5′-substituted
phenyl-2′,4′-dihydrospiro[indoline-3,3′-pyrazol]-2-one (20–
24) analogs showed a distinctive pattern of selectivity.
Compound 3-(2-phenyl-2-((5-phenyl-1,3,4-thiadiazol-2-yl)
Antitumor activity
Seven newly synthesized compounds (15, 16, 20, 21, 22,
23, and 24) were selected by National Cancer Institute
(NCI) Developmental Therapeutic Program (http://www.

Med Chem Res
Table 2 Sixty human tumor cell lines anticancer screening data of synthetic analogues
Growth percent in one-dose assay (The most sensitive cell lines)
Panel/cell line
15
16
20
21
22
23
24
NSC 767490
NSC 767496
NSC 767491
NSC 767492
NSC 767493
NSC 767494
NSC 767495
Leukemia
CCRF-CEM
HL-60(TB)
K-562
−45.05
−32.88
20.39
−42.66
−31.81
8.67
49.17
−8.55
18.49
38.71
47.28
−7.86
88.3
84.37
87.78
81.14
81.82
83.45
73.01
32.34
−4.96
23.76
36.34
28.3
102.86
100.42
96.68
94.72
82.75
91.5
99.13
94.54
83.78
77.78
86.22
MOLT-4
RPMI-8226
SR
−24.19
−17.47
−22.97
−26.44
−14.37
−27.6
12.5
Non-small cell lung cancer
NCI-H522
Colon Cancer
COLO 205
HCT-116
HT29
−59.34
−95.65
24.58
90.07
88.89
20.02
95.86
2.53
−51.94
−36.27
0.63
−58.54
−56.29
31.37
29.39
8.14
108.37
95.32
97.12
106.75
102.06
106.72
30.54
22.9
100.05
87.96
12.15
106.59
Melanoma
LOX IMVI
Renal cancer
786–0
−86.29
−79.3
48.36
99.48
97.18
51.91
101.88
−19.27
−54.79
−87.25
34.61
−56.92
−71.4
−69.15
20.82
61.72
59.35
57.58
48.18
73.11
115.56
100.24
91.04
69.22
96.33
27.11
47.14
97.1
99.71
103.54
99.48
31.02
57.41
46.83
49.06
48.4
102.31
90.88
82.51
98.39
16.57
43.81
ACHN
UO-31
Mean
42.38
63.47
103.08
Delta
121.86
193.33
116.47
199.41
Range
79.18
imino)ethylidene) indolin-2-one (15) and 3-(2-((5-(4-chlor-
ophenyl)-1,3,4-thiadiazol-2-yl)imino)-2-phenyl ethylidene)
indolin-2-one (16) showed remarkably lowest cell growth
promotion against Non-small lung NCI-H522 cancer cell
line with cell growth promotion of −59.34 and −95.65
respectively and also showed lethality against Melanoma
LOX IMVI cancer cell line with −86.29 and −79.30
respectively. Lowest cell growth promotion are also
observed by compound 15 against Leukemia CCRF-CEM
(−45.05), HL-60 (−32.88), MOLT-4 (−24.19), RPMI-
8226 (−17.47), and SR (−22.97); Colon cancer HCT-116
(−51.94). The compound 16 also showed significant cyto-
toxic activity against Leukemia CCRF-CEM (−42.66), HL-
60 (−31.81), MOLT-4 (−26.44), RPMI-8226 (−14.37),
and SR (−27.60) Colon cancer HCT-116 (−58.54). Com-
pounds 15, 16, 20 and 23 showed growth promotion values
of 2.53, 0.63, 31.37, and 30.54, against Colon COLO 205
respectively; while compound 20 and 23 showed values of
8.14 and 12.15 against Colon HT29. Through evaluation of
the data revealed in (Table 2) showed compounds 15, 16,
20, and 23 are the most potent of this study, displaying
usefulness towards various cell types belong to distinct
tumor subpanels. Compounds 15, 16, 20, and 23 showed
80
60
40
20
0
65.39
57.62
51.82
3.67
0.52
1.61
24
15
16
20
21
Compound
22
23
Fig. 4 Mean inhibition percentages of the compounds in single dose
(10 µM)
higher percent mean inhibition than 21, 22, and 24. Com-
pound with chloro substitution on phenyl ring was more
active than compound 15 with unsubstituted phenyl ring.
Also compound 20 and 23 were more active than 21, 22,
and 24 (Fig. 4).
Compounds 15, 16, 20, and 23 passed the prime antic-
ancer assay at strength of 10 µM. Subsequently, these active
compounds tested towards a panel of sixty distinct tumor
cell types at a 5-log dose range. Two of these four analo-
gues were selected for a repeat screen (15 and 16) and the

Med Chem Res
Table 3 GI50 values (µM) of the tested compounds over the most sensitive cell line of each subpanel
Compound No Cancer cell lines
CCRF-CEMa HOP-92b NCI-522b HCT-116c SF-295d SNB-75d MDA-MB-435e OVCAR-3f A498g PC-3h BT-549i
15*
16*
20
1.51
1.17
5.49
3.63
0.99
0.97
1.65
1.66
0.65
0.72
4.66
3.56
1.35
1.07
4.83
4.27
17.09
12.17
4.84
3.72
2.53
2.98
1.35
2.96
2.57
1.66
4.64
1.39
1.28
5.1
9.85
2
1.92
10.51 1.93 1.8
1.85 3.89 6.35
2.24 2.28 1.3
23
2.77
3.26
* Values are average of two runs; a Leukemia cell lines; b Non-small Cell lung cancer cell lines; c Colon cancer cell lines; d CNS cancer cell lines;
e
f
g
h
i
Melanoma cell lines; Ovarian cancer cell lines; Renal cancer cell lines; Prostate; Breast cancer cell lines
100
results obtained are shown in Table 3, as the average of
these two runs. Compounds 15, 16, 20, and 23 showed
remarkable broad-spectrum antitumor activity.
95.4
100
90
80
70
60
50
40
30
20
10
0
69.18
The entire cell lines (about 60), representing nine tumor
subpanels were incubated at five different concentrations
(0.01, 0.1, 1, 10, and 100 µM). Three response parameters
GI50, TGI, and LC50 were calculated for each cell line.
Tested compounds 15, 16, 20, and 23 displayed effective
growth inhibition GI50 (MG-MID) values of 3.01, 2.81,
6.02, and 4.07 μM, respectively, beside cytostatic activity
TGI (MG-MID) values of 8.70, 8.51, 69.18, and 30.9 μM,
respectively (Fig. 5). In addition, they exhibited some
cytotoxic activity with LC50 (MG-MID) values of 29.5,
30.9, 100, and 95.4 μM, respectively as shown in Fig. 5.
Compound 3-(2-phenyl-2-((5-phenyl-1,3,4-thiadiazol-2-
yl) imino)ethylidene) indolin-2-one (15) demonstrated
remarkable anticancer activity towards almost all of the
tested cell lines on behalf of nine distinct subpanels with
GI50 values between “0.65–9.85 µM”, expect two cell lines
SF-295 and SNB-19 of CNS cancer subpanel showing GI50
at a concentration of 17.09 and 12.29 µM respectively. The
results are shown in Table 3, with regard to sensitivity
against some individual cell lines the compound showed
high activity against Non-Small Cell Lung Cancer NCI-
H522 and HOP-92 with GI50 0.65 and 0.99 µM respec-
tively. GI50, TGI, and LC50 MG-MID values of 3.01, 8.70,
and 29.5 μM respectively, proved to be the most active
member in this study. On the other hand, 3-(2-((5-(4-
chlorophenyl)-1,3,4-thiadiazol-2-yl)imino)-2-phenyl ethyli-
dene) indolin-2-one (16) showed nearly the same pattern of
activity as 15 but to a lesser extent. This compound is active
towards non-small cell lung cancer (NCI-H522 and HOP-
92) and colon (HCT-116) with GI50 values 0.72, 0.97, and
1.07 µM respectively. The results are presented in Table 3.
5-Bromo-5′-phenyl-2′,4′-dihydrospiro[indoline-3,3′-pyr-
azol]-2-one (23) is active against CNS cancer (SNB-75),
colon cancer (HCC-2998), and non-small lung cell cancer
(HOP-92) showing GI50 values 1.35, 1.59, and 1.66 µM
respectively. The results of compound 23 at five dose level
in μM are shown in Table 3. The compounds displayed
relatively weaker growth inhibition, cytostatic, and
30.9
30.9
29.5
8.7
8.51
6.02
4.07
3.01
2.81
15
16
20
23
Compound
GI50
TGI
LC50
Fig. 5 GI50, TGI, LC50MG-MID of in vitro cytotoxicity data for
compounds 15, 16, 20, and 23 against human tumor cell lines
cytotoxic patterns when compared with compound 15 and
compound 16 (GI50, TGI, and LC50MG-MID values 4.07,
30.9, and 95.49 μM, respectively). Finally, 5′-phenyl-2′,4′-
dihydrospiro[indoline-3,3′-pyrazol]-2-one
(20)
active
against Melanoma (MDA-MB-435), non-small cell lung
cancer (HOP-92) and renal cancer (A498) with GI50 values
1.66, 1.65, and 1.85 µM respectively. The compound 20
shows significant activity against all cancer cell lines except
on ovarian (OVCAR-4 and OVCAR-5) and non-small cell
lung cancer (NCI-H226). The results are shown in Table 3.
The compound has shown weaker growth inhibition, cyto-
static, and cytotoxic patterns with GI50, TGI, and LC50 MG-
MID values 6.02, 69.18, and 100 μM (Fig. 5).
Conclusion
In conclusion, we have synthesized a new series of isatin
based thiadiazoline and pyrazoline derivatives as a novel
class of antitumor agents. Among these compounds 3-(2-
Phenyl-2-((5-phenyl-1,3,4-thiadiazol-2-yl)imino)ethylidene)
indolin-2-one (15) and 3-(2-((5-(4-chlorophenyl)-1,3,4-thia-
diazol-2-yl)imino)-2-phenylethylidene)indolin-2-one (16)
displayed significant selective cytotoxic activity against non-

Med Chem Res
JNK3 MAP kinase inhibitors. Bioorg Med Chem Lett 19
(10):2891–2895
small cell lung cancer (NCI-H522) with GI50 0.65 and 0.72
µM respectively. Thus, structure-activity investigation
revealed that isatin-thiadiazole conjugates displayed high
significant activity compared to that of spiroisatin–pyrazoline
derivatives. Docking studies performed on the synthesized
compounds by using VLife Molecular Design Suite 4.3 soft-
ware, has confirmed that inhibitors fit into the binding pocket
of the EGFR, 4ICZ protein. From the results, we found that
for successful docking, hydrogen bonding and hydrophobic
interactions between the ligand and the receptor are very
important. Further studies will be undertaken to elucidate the
antitumor mechanism of action involved.
Chapman JG, Magee WP, Stukenbrok HA, Beckius GE, Milici AJ,
Tracey WR (2002) A novel nonpeptidic caspase-3/7 inhibitor,(S)-
(+)-5-[1-(2-methoxymethylpyrrolidinyl) sulfonyl] isatin reduces
myocardial ischemic injury. Eur J Pharmacol 456(1):59–68
Chen M, Lin S, Li L, Zhu C, Wang X, Wang Y, Jiang B, Wang S, Li
Y, Jiang J (2012) Enantiomers of an indole alkaloid containing
unusual dihydrothiopyran and 1, 2, 4-thiadiazole rings from the
root of Isatis indigotica. Org Lett 14(22):5668–5671
Dandia A, Saini D, Bhaskaran S, Saini DK (2014) Ultrasound pro-
moted green synthesis of spiro [pyrano [2, 3-c] pyrazoles] as
antioxidant agents. Med Chem Res 23(2):725–734
Eldehna WM, Altoukhy A, Mahrous H, Abdel-Aziz HA (2015)
Design, synthesis and QSAR study of certain isatin-pyridine
hybrids as potential anti-proliferative agents. Eur J Med Chem
90:684–694
Fall Y, Barreiro C, Fernández C, Mouriño A (2002) Vitamin D het-
erocyclic analogues. Part 1: A stereoselective route to CD sys-
tems with pyrazole rings in their side chains. Tetrahedron Lett 43
(8):1433–1436. doi:10.1016/S0040-4039(02)00031-X
Fares M, Eldehna WM, Abou‐Seri SM, Abdel‐Aziz HA, Aly MH,
Tolba MF (2015) Design, synthesis and in vitro antiproliferative
activity of novel isatin‐quinazoline hybrids. Arch Pharm (Wein-
heim) 348(2):144–154
Acknowledgements The authors would like to thank the National
Cancer Institute (NCI), Bethesda, MD, USA for performing the anti-
tumor testing of the synthesized compounds.
Compliance with ethical standards
Conflict of interest The authors declare that they have no competing
interests.
Garcia M, Jemal A, Ward E, Center M, Hao Y, Siegel R, Thun M
(2007) Global cancer facts & figures 2007. American cancer
society, Atlanta, GA, p 52. 1 (3)
References
Grever MR, Schepartz SA, Chabner BA (1992) The National Cancer
Institute: cancer drug discovery and development program. In:
Seminars in oncology, 1992. vol 6. WB SAUNDERS CO
INDEPENDENCE SQUARE WEST CURTIS CENTER, STE
300, PHILADELPHIA, PA 19106-3399, pp 622-638
Havrylyuk D, Zimenkovsky B, Lesyk R (2015) Synthesis, biological
activity of thiazolidinones bearing indoline moiety and isatin
based hybrids. Mini Rev Org Chem 12(1):66–87
Havrylyuk D, Zimenkovsky B, Vasylenko O, Gzella A, Lesyk R
(2012) Synthesis of new 4-thiazolidinone-, pyrazoline-, and
isatin-based conjugates with promising antitumor activity. J Med
Chem 55(20):8630–8641
Ibrahim HS, Abou-Seri SM, Tanc M, Elaasser MM, Abdel-Aziz HA,
Supuran CT (2015) Isatin-pyrazole benzenesulfonamide hybrids
potently inhibit tumor-associated carbonic anhydrase isoforms IX
and XII. Eur J Med Chem 103:583–593
Jemal A, Bray F, Center MM, Ferlay J, Ward E, Forman D (2011)
Global cancer statistics. CA Cancer J Clin 61(2):69–90
Karthikeyan C, SH Narayana Moorthy N, Ramasamy S, Vanam U,
Manivannan E, Karunagaran D, Trivedi P (2015) Advances in
chalcones with anticancer activities. Recent Pat Anticancer Drug
Discov 10(1):97–115
Lesyk R, Havrylyuk D, Lelyukh M (2015) Synthesis and anticancer
activity of isatin, oxadiazole and 4-thiazolidinone based conjugates,
Chem & Chem Technol 9(1):29–36
Liang C, Xia J, Lei D, Li X, Yao Q, Gao J (2014) Synthesis, in vitro
and in vivo antitumor activity of symmetrical bis-Schiff base
derivatives of isatin. Eur J Med Chem 74:742–750
Medvedev A, Buneeva O, Glover V (2007) Biological targets for isatin
and its analogues: implications for therapy. Biol Targets Ther 1
(2):151
Abraham J (2014) Paving the way for biosimilars in oncology, Part 2:
Focus on safety and clinical trial considerations. Semin Oncol,
41:S1–S2
Alley MC, Scudiero DA, Monks A, Hursey ML, Czerwinski MJ, Fine
DL, Abbott BJ, Mayo JG, Shoemaker RH, Boyd MR (1988)
Feasibility of drug screening with panels of human tumor cell
lines using a microculture tetrazolium assay. Cancer Res 48
(3):589–601
Altıntop MD, Özdemir A, Turan-Zitouni G, Ilgın S, Atlı Ö, Demirel R,
Kaplancıklı ZA (2015) A novel series of thiazolyl–pyrazoline
derivatives: synthesis and evaluation of antifungal activity,
cytotoxicity and genotoxicity. Eur J Med Chem 92:342–352
Andreani A, Burnelli S, Granaiola M, Leoni A, Locatelli A, Morigi R,
Rambaldi M, Varoli L, Calonghi N, Cappadone C (2008) Anti-
tumor activity of new substituted 3-(5-Imidazo [2, 1-b] thiazo-
lylmethylene)-2-indolinones and 3-(5-imidazo [2, 1-b]
thiadiazolylmethylene)-2-indolinones: selectivity against colon
tumor cells and effect on cell cycle-related events (1). J Med
Chem 51(23):7508–7513
Bari S, Mandab S, Ugalec V, Jupallyb VR, Akenab V (2015) Rational
design and synthesis of benzothiazolo-isatins for antimicrobial
and cytotoxic activities. Indian J Chem B 54(3):418–429
Boyle P, Levin B (2008) World cancer report 2008. IARC Press,
International Agency for Research on Cancer, Lyon, France
Bursavich MG, Gilbert AM, Lombardi S, Georgiadis KE, Reifenberg
E, Flannery CR, Morris EA (2007) 5′-Phenyl-3′H-spiro[indoline-
3,2′-[1,3,4]thiadiazol]-2-one inhibitors of ADAMTS-5 (Aggre-
canase-2). Bioorg Med Chem Lett 17(20):5630–5633. doi:10.
1016/j.bmcl.2007.07.048
Mohammadizadeh MR (2006) One-pot rapid and efficient synthesis of
new spiro derivatives of 11H-indeno [1, 2-b] quinoxalin-11-one,
6H-indeno [1, 2-b] pyrido [3, 2-e] pyrazin-6-one and isatin-based
2-pyrazolines. Arkivoc 11:47–58
Monteiro Â, Gonçalves LM, Santos MM (2014) Synthesis of novel
spiropyrazoline oxindoles and evaluation of cytotoxicity in can-
cer cell lines. Eur J Med Chem 79:266–272
Cane A, Tournaire M-C, Barritault D, Crumeyrolle-Arias M (2000)
The endogenous oxindoles 5-hydroxyoxindole and isatin are
antiproliferative and proapoptotic. Biochem Biophys Res Com-
mun 276(1):379–384
Cao J, Gao H, Bemis G, Salituro F, Ledeboer M, Harrington E,
Wilke S, Taslimi P, Pazhanisamy S, Xie X (2009) Structure-based
design and parallel synthesis of N-benzyl isatin oximes as

Med Chem Res
Nikalje APG, Shaikh SI, Khan FAK, Shaikh S, Sangshetti JN (2015)
Molecular sieves promoted, ultrasound-mediated synthesis, bio-
logical evaluation and docking study of 3-(5-substituted-1, 3, 4-
thiadiazol-2-ylimino) indolin-2-ones as a potential anticonvulsant
agents. Med Chem Res 24(12):4058–4069
Singh S, Bharti N, Mohapatra PP (2009) Chemistry and biology of
synthetic and naturally occurring antiamoebic agents†. Chem Rev
109(5):1900–1947
Socca EAR, Luiz-Ferreira A, de Faria FM, de Almeida AC, Dunder
RJ, Manzo LP, Brito ARMS (2014) Inhibition of tumor necrosis
Pao W, Miller V, Zakowski M, Doherty J, Politi K, Sarkaria I, Singh
B, Heelan R, Rusch V, Fulton L (2004) EGF receptor gene
mutations are common in lung cancers from “never smokers” and
are associated with sensitivity of tumors to gefitinib and erlotinib.
Proceedings of the National Academy of Sciences of the United
States of America 101(36):13306–13311
Reddy CN, Nayak VL, Mani GS, Kapure JS, Adiyala PR, Maurya RA,
Kamal A (2015) Synthesis and biological evaluation of spiro
[cyclopropane-1, 3′-indolin]-2′-ones as potential anticancer
agents. Bioorg Med Chem Lett 25(20):4580–4586
Rekulapally S, Jarapula R, Gangarapu K, Manda S, Vaidya JR (2015)
In silico and in vitro studies of novel 7-azaindole and 7-azaisatin
derivatives as potent anticancer agents. Med Chem Res 24
(9):3412–3422
Ribeiro CJ, Amaral JD, Rodrigues CM, Moreira R, Santos MM (2016)
Spirooxadiazoline oxindoles with promising in vitro antitumor
activities. Med Chem Comm 7(3):420–425
factor-alpha and cyclooxigenase-2 by isatin: a molecular
mechanism of protection against TNBS-induced colitis in rats.
Chem Biol Interact 209:48–55
Thadhaney B, Sain D, Pemawat G, Talesara G (2010) Synthesis and
antimicrobial evaluation of ethoxyphthalimide derivatized spiro
[indole-3, 5’-(1, 3) thiazolo (4, 5-c) isoxazol]-2 (1H)-ones via ring
closure metathesis. Indian J Chem B 49(3):368
Thi Lan Huong T, Thi Mai Dung D, Thi Kim Oanh D, Thi Bich Lan T,
Thi Phuong Dung P, Loi VD, Woo Han B, Yun J, Soon Kang J,
Kim Y (2015) 5-Aryl-1, 3, 4-thiadiazole-based hydroxamic acids
as histone deacetylase inhibitors and antitumor agents: synthesis,
bioevaluation and docking study. Med Chem 11(3):296–304
Thun MJ, DeLancey JO, Center MM, Jemal A, Ward EM (2010) The
global burden of cancer: priorities for prevention. Carcinogenesis
31(1):100–110
Varma RS, Khan IA (2014) Isatins as potential biologically active
agents. Def Sci J 28(4):191–202
Schmidt A, Dreger A (2011) Recent advances in the chemistry of
pyrazoles. Properties, biological activities, and syntheses. Curr
Org Chem 15(9):1423–1463
Shaaban MR, Mayhoub AS, Farag AM (2012) Recent advances in the
therapeutic applications of pyrazolines. Expert Opin Ther Pat 22
(3):253–291
Shih M-H, Xu Y-Y, Yang Y-S, Lin G-L (2015) A facile synthesis and
antimicrobial activity evaluation of sydnonyl-substituted thiazo-
lidine derivatives. Molecules 20(4):6520–6532
Shoemaker RH (2006) The NCI60 human tumour cell line anticancer
drug screen. Nat Rev Cancer 6(10):813–823
Vineis P, Wild CP (2014) Global cancer patterns: causes and pre-
vention. Lancet 383(9916):549–557
Yusuf M, Jain P (2014) Synthesis and biological significances of 1, 3,
4-thiadiazolines and related heterocyclic compounds. Arab J
Chem 7(5):525–552
Zhou L, Liu Y, Zhang W, Wei P, Huang C, Pei J, Yuan Y, Lai L
(2006) Isatin compounds as noncovalent SARS coronavirus 3C-
like protease inhibitors. J Med Chem 49(12):3440–3443
Ziarani GM, Moradi R, Lashgarib N (2016) Synthesis of spiro-fused
heterocyclic scaffolds through multicomponent reactions invol-
ving isatin. ARKIVOC 1:1–81