84
K. Kumar et al. / European Journal of Medicinal Chemistry 86 (2014) 81e86
4000e400 cmꢁ1 using the ATR accessory (with a diamond crystal)
on a Nicolet 6700 FT IR spectrophotometer.
Table 1
Anti-proliferative effects of complex 6 and etoposide on different cell lines after 24,
48, and 72 h treatment. Selectivity index (SI) was calculated after 72 h of treatment.
Data are expressed as IC50 (mM). IC50 is defined as the concentration required to
achieve 50% inhibition over control cells (0.5% DMSO); IC50 values are shown as
mean standard error values taken from three independent experiments.
4.1. Procedure for the synthesis and characterization of N1-(7-
chloro-quinolin-4-yl)-ethylamino-2-acetylpyridine-
thiosemicarbazone (5)
Cell line
Compound Time treatment
24 h 48 h
Selectivity
index (SI)
72 h
To 4.8 g (0.02 mol) of 3 dissolved in 100 ml of EtOH was added
0.02 mol of N1-(7-Chloro-quinolin-4-yl)-ethane-1,2-diamine 4. The
resulting solution was heated under reflux until the evolution of
methyl mercaptan almost completely ceased as detected by the
yellow color it imparts to moistened Pb(OAc)2 paper placed at the
mouth of the reflux condenser. Reaction time was 20 h and the
resulting thiosemicarbazone got crystallized from hot solution
during the progress of reaction. The crystals were collected, washed
with cold diethyl ether and dried under reduced pressure.
HCT-116
Caco-2
HT-29
Complex 6 14.26 1.37 2.96 0.74 0.55 0.39 21.47
Etoposide 38.10 1.20 26.70 1.60 17.10 1.60 2.53
Complex 6 19.56 1.57 11.96 1.03 4.02 0.78 2.94
Etoposide 32.90 1.90 19.00 1.80 16.50 1.30 2.62
Complex 6 19.66 1.37 13.63 1.35 7.25 1.27 1.63
Etoposide 35.10 1.70 21.90 1.60 19.30 1.80 2.24
CCD-18Co Complex 6 28.24 1.72 21.13 1.53 11.81 1.42
Etoposide 58.90 2.10 49.30 1.60 43.20 1.80
4.1.1. N1-(7-chloro-quinolin-4-yl)-ethylamino-2-acetylpyridine-
thiosemicarbazone (5)
Yield 82%; Off White Solid; m.p. 203e204 ꢀC; 1H NMR (DMSO-
d6, 400 MHz):
d
2.41 (s, 3H, eCH3); 3.57 (dd, J ¼ 2.1, 5.7 Hz, 2H,
eCH2e); 3.97 (dd, J ¼ 2.1, 5.7 Hz, 2H, eCH2e); 6.77 (d, J ¼ 5.5 Hz,1H,
Hb); 7.41 (m, 1H, PyridylH); 7.47 (dd, J ¼ 2.2, 9.0 Hz, 1H, Hd); 7.52 (t,
J
¼
5.1 Hz, eNHe, exchangeable with D2O); 7.82 (m, 2H,
He þ PyridylH); 8.29 (d, J ¼ 9.0 Hz, 1H, Hc); 8.32 (d, J ¼ 8.0 Hz, 1H,
PyridylH); 8.43 (d, J ¼ 5.4 Hz, 1H, Ha); 8.60 (d, J ¼ 4.13, 1H, Pyr-
idylH); 8.87 (t, J ¼ 6.1 Hz, eNHe, exchangeable with D2O); 10.50 (s,
eNHe, exchangeable with D2O); 13C NMR(DMSO-d6, 100 MHz):
12.3, 41.9, 98.9, 117.3, 120.7, 123.9, 124.0, 124.1, 127.4, 133.4, 136.3,
148.5, 148.7, 148.8, 150.2, 151.7, 154.6, 178.4; HRMS: Calcd for
C
19H19ClN6S [MþH]þ 399.1153, found 399.1112; Anal. Calcd (%) for:
C, 57.21; H, 4.80; N, 21.07, found: C, 57.19; H, 4.77; N, 21.10. FT IR (v/
cmꢁ1): 1265(C]S), 1609(C]N).
4.2. Procedure for the synthesis and characterization of complex (6)
To the stirred solution of ligand 5 (615 mg, 0.771 mmol) in
ethanol (60 ml) was added Ga(NO3)3$xH2O (184 mg, 0.355 mmol)
in small portions. The resulting yellow solution was refluxed with
stirring for 2 h; cooled to room temperature until crystalline yellow
solid separates out. The solution was then filtered and washed with
cold ethanol twice under reduced pressure to obtain the complex 6
(609 mg).
Fig. 1. Effect of complex 6 and etoposide on various cancer cell lines after 24, 48, and
72 h treatment.
4.2.1. Complex (6)
Yield 45.5%; Yellow solid; m.p. >250 ꢀC; 1H NMR (DMSO-d6,
300 MHz):
d 2.43 (s, 3H, eCH3); 2.66 (s, 3H, eCH3); 3.09 (s, 2H,
eNCH2); 3.65 (s, 6H, 3xNCH2); 6.85 (d, J ¼ 6.0 Hz, 1H, CQ-H); 6.98
(d, J ¼ 6.0 Hz, 1H, CQ-H); 7.51 (s, 1H, eNHe); 7.67e7.85 (m, 7H,
eArH); 8.10e8.16 (m, 2H, eArH); 8.35e8.41 (m, 7H, eArH); 8.85 (s,
1H, eNHe); 9.38 (s, 1H, eNHe); 10.42 (s, 1H, eNHe); 13C NMR
(DMSO-d6, 100 MHz): 12.3, 13.3, 41.7, 42.3, 43.0, 45.0, 98.8, 98.9,
115.0, 115.5, 115.6, 119.0, 119.2, 120.8, 121.7, 124.1, 125.6, 126.9, 127.4,
136.9, 138.1, 138.3, 138.4, 142.8, 143.2, 148.4, 148.6, 149.0, 152.5,
154.1, 156.0, 156.6, 160.8, 162.1, 166.2, 173.8; m/z (HRMS, positive
mode): 865.1246 (100%, [MꢁNO3]þ); CHN: Calcd for
C
78H178Cl2GaN13O34S2, C, 45.76; H, 8.76; N, 8.89. Found: C, 45.62; H,
8.71; N, 8.96; FT IR (v/cmꢁ1): 1614 (C]N), 2929 (NH), 3273 (OH).
Fig. 2. Doseeresponse curve of the complex 6 against 3D7 isolate of P. falciparum,
asexual blood stage.
4.3. Cell lines and culture conditions
(St. Louis, MO, USA) or other commercial vendors and used as
received. Microanalyses (C, H, N) were performed by CHN analysis
by the Microanalysis Laboratory at the University of Illinois Urbana/
Champaign, U.S.A. FT IR spectra were acquired in the range
Human colon cancer cell lines Caco-2 (adenocarcinoma), HT-29
(adenocarcinoma) and HCT-116 (carcinoma) and the normal colon
cells CCD-18Co were obtained from American Type Culture
Collection (Rockville, USA). Caco-2 cells were grown in EMEM