Anticancer activity of novel indenopyridine derivatives

Article abstract of DOI:10.1007/s12272-012-0605-x

Eighteen new 4-[2-amino-3-cyano-5-oxo-4-substitutedaryl-4H-indeno[1,2-b] pyridin-1-(5H)-yl]benzenesulfonamide derivatives 6a-q were synthesized via a reaction of aromatic aldehydes, enaminone 3 and malononitrile in one-pot reaction. Also, compounds 6a-q were obtained, via another route by reaction of enaminone 3 with arylidenemalononitriles 4a-q. The structure of the synthesized compounds was characterized by microanalysis, IR, ¹H-NMR, ¹³C-NMR and mass spectral data. All the target compounds were subjected to in vitro anticancer activity against breast cancer cell line (MCF7). Compound 6d showed a higher potency with IC₅₀ value (4.34 μM) than that of the Doxorubicin (5.40 μM), as the reference drug, while compound 6n with IC50 value (6.84 μM) is nearly as active as Doxorubicin. Also, compounds 6a-c, 6e, 6f, 6h and 6p exhibited a moderate activity, while compounds 3, 6g, 6i-m, 6o and 6q showed weak activity.

Full text of DOI:10.1007/s12272-012-0605-x

Arch Pharm Res Vol 35, No 6, 987-994, 2012
DOI 10.1007/s12272-012-0605-x
Anticancer Activity of Novel Indenopyridine Derivatives
Mostafa M. Ghoraband Mansour S. Al-Said
Medicinal, Aromatic and Poisonous Plants Research Center (MAPPRC), College of Pharmacy, King Saud University, Riy-
adh 11451 Saudi Arabia
(Received October 29, 2011/Revised January 2, 2012/Accepted January 4, 2012)
Eighteen new 4-[2-amino-3-cyano-5-oxo-4-substitutedaryl-4
zenesulfonamide derivatives 6a were synthesized via a reaction of aromatic aldehydes,
enaminone and malononitrile in one-pot reaction. Also, compounds 6a were obtained, via
. The structure of
H-indeno[1,2-b]pyridin-1-(5H)-yl]ben-
-
q
3
-q
another route by reaction of enaminone
3 with arylidenemalononitriles 4a-q
1
the synthesized compounds was characterized by microanalysis, IR, H-NMR, 13C-NMR and
mass spectral data. All the target compounds were subjected to in vitro anticancer activity
against breast cancer cell line (MCF7). Compound 6d showed a higher potency with IC50 value
(4.34
IC50 value (6.84
exhibited a moderate activity, while compounds
µ
M) than that of the Doxorubicin (5.40
M) is nearly as active as Doxorubicin. Also, compounds 6a
6g 6i 6o and 6q showed weak activity.
µ
M), as the reference drug, while compound 6n with
µ
-c,
6e 6f 6h and 6p
,
,
3
,
,
-m,
Key words: Indenopyridines, Sulfonamides, Anti-breast cancer activity
reported to show substantial anticancer activity in
vitro and in vivo (Supuran et al., 2004). Several mech-
INTRODUCTION
Cancer is the leading cause of mortality to human anisms have been reported for anticancer activity of
beings. Thus, there exists a great urgency to develop the sulfonamide compounds and the most prominent
highly efficacious and minimally toxic treatments for of these mechanisms were through the inhibition of
cancer. Although tremendous progress has been achieved the carbonic anhydrase (Maren, 1976; Supuran and
in the development of novel cancer treatments, most Scozzafava, 2000; Kivelä et al., 2005; Turkmen et al.,
of the current cancer drugs usually exhibit high tox- 2011). The mechanism of tumor inhibition by sulfon-
icity and are severely resisted by tumor cells, in clinical amide carbonic anhydrase (CA) inhibitor was suggested
practice. This dilemma is particularly true for DNA- by Chegwidden et al. (2000). These compounds may
damaging agents, the mainstay of cancer treatment reduce the provision of bicarbonate for the synthesis
(Hurley, 2002). Indenopyridines were found to possess of nucleotides and other cell components, such as
several pharmacological properties, including anticancer membrane lipids. In continuation of our work (Ghorab
activity (Israel et al., 1972; Utsugi et al., 1997; Manpadi et al., 2010) it seemed of interest to design and synthe-
et al., 2007; Vigante et al., 2007; Ghahremanzadeh et size a novel series of indeno[1,2-
b]pyridines, carrying
al., 2010). Also, the sulfonamides constitute an impor- a biologically active sulfonamide moiety to be evaluated
tant class of drugs, with several types of pharmaco- as potential anticancer agents.
logical agents, which possesses anticancer activity
(Abbate et al., 2004; Ghorab et al., 2006; Ismail et al.,
2006; Rostom, 2006) among others. A large number of
structurally novel sulfonamides have ultimately been
MATERIALS AND METHODS
Materials
Melting points (oC, uncorrected) were determined in
open capillaries on a Gallenkemp melting point appar-
atus (Sanyo Gallenkemp). Precoated silica gel plates
(silica gel 0.25 mm, 60 G F 254; Merck) were used for
thin layer chromatography, dichloromethane-methanol
(9.5:0.5 mL) mixture was used as a developing solvent
Correspondence to: Mostafa M. Ghorab, Medicinal, Aromatic
and Poisonous Plants Research Center (MAPPRC), College of
Pharmacy, King Saud University, Riyadh 11451 Saudi Arabia
Tel: 966-534292860, Fax: 966-01-4670560
E-mail: mmsghorab@yahoo.com
987

988
M. M. Ghorab and M. S. Al-Said
system and the spots were visualized by ultraviolet [m, 15H, Ar-H + SO2NH2]. 13C-NMR (DMSO-d6): 39.0,
light and/or iodine. Infrared spectra were recorded, 57.9, 102.9, 118.3, 119.6, 125.1, 126.5, 127.8, 128.2,
in KBr discs, using IR-470 Shimadzu spectrometer 128.8, 129.1, 129.9, 130.2, 135.7, 138.6, 139.2, 140.5,
1
(Shimadzu). H-NMR spectra (in DMSO-d6) were re- 147.3, 153.0, 169.4, 194.6. MS m/z (%) 454 [M+] (1.92),
corded on Bruker Ac-300 ultra shield NMR spectro- 233 (100). Anal. Calcd for C25H18N4O3S: C, 66.07; H,
meter (Bruker,
internal standard. Electron impact Mass Spectra were
δ ppm), at 300 MHz, using TMS as 3.99; N, 12.33. Found: C, 66.30; H, 3.70; N, 12.70.
recorded on a, Shimadzu Gc-Ms-Qp 5000 instrument 4-[2-Amino-3-cyano-5-oxo-4-tolyl-4H-indeno[1,2-b]
(Shimadzu). Elemental analyses were performed on pyridin-1-(5
Carlo Erba 1108 Elemental Analyzer (Heraeus). All Yield, 81%; m.p. 104-106oC; IR (KBr, cm−1): 3432,
compounds were within ± 0.4% of the theoretical values. 3327, 3290 (NH2), 2986, 2840 (CH aliph.), 2191 (C N),
1720 (C=O), 1368, 1188 (SO2). H-NMR (DMSO-d6):
H)-yl]benze-nesulfonamide (6b)
≡
1
δ
2.3 [s, 3H, CH3], 4.4 [s, 1H, CH], 6.9 [s, 2H, NH2 ex-
changeable with D2O], 7.1-7.8 [m, 14H, Ar-H + SO2NH2].
Synthesis
4-(3-Oxo-3
H
-inden-1-yl-amino)benzenesulfonamide 13C-NMR (DMSO-d6): 24.3, 40.0, 61.8, 96.0, 118.5,
119.8, 123.7, 127.0, 127.9, 128.8, 129.5, 130.7, 135.7,
(3)
A mixture of indane-1,3-dione
1 (1.49 g, 0.01 mol) 137.3, 138.2, 139.1, 140.4, 147.3, 153.0, 168.6, 196.2.
and sulfanilamide
2
(1.72 g, 0.01 mol) in ethanol (30 MS m/z (%) 468 [M+] (3.58), 105 (100). Anal. Calcd for
mL) was refluxed for 4 h. The reaction mixture was C26H20N4O3S: C, 66.65; H, 4.30; N, 11.96. Found: C,
cooled and poured onto ice-water. The obtained solid 66.40; H, 4.60; N, 11.70.
was crystallized from dioxane to give
Yield, 74%; m.p. 194-196oC; IR (KBr, cm−1): 3345, 3330, 4-[2-Amino-3-cyano-5-oxo-4-(2-hydroxyphenyl)-4
3300 (NH, NH2), 1715 (C=O), 1372, 1158 (SO2). 1H-NMR indeno[1,2-
]pyridin-1-(5 )-yl]benzenesulfonamide
(DMSO-d6): 7.3-7.9 [m, 10H, Ar-H + SO2NH2], 9.0 [s, (6c)
1H, CH], 10.5 [s, 1H, NH]. 13C-NMR (DMSO-d6): 98.0, Yield, 69%; m.p. 170-172oC; IR (KBr, cm−1): 3390 (OH),
116.9, 125.1, 127.2, 128.4, 130.0, 130.5, 134.2, 135.6, 3343, 3300, 3270 (NH2), 2184 (C N), 1684 (C=O), 1333,
137.0, 145.8, 158.3, 200.4. MS m/z (%): 300 [M+] (15.6), 1152 (SO2). 1H-NMR (DMSO-d6):
5.1 [s, 1H, CH], 6.8
3.
H-
b
H
δ
≡
δ
64 (100). Anal. Calcd. for C15H12N2O3S: C, 59.99; H, 4.03; [s, 2H, NH2 exchangeable with D2O], 9.1 [s, 1H, OH].
N, 9.33. Found: C, 59.60; H, 4.40; N, 9.70.
13C-NMR (DMSO-d6): 30.8, 56.0, 102.0, 116.8, 118.5,
119.8, 121.9, 124.3, 126.4, 127.8, 128.4, 128.6, 129.0,
129.8, 130.2, 131.1, 134.8, 137.2, 140.7, 149.8, 160.8,
165.9, 190.4. MS m/z (%) 470 [M+] (1.5), 63 (100).
Anal. Calcd for C25H18N4O4S: C, 63.82; H, 3.86; N,
4-[2-Amino-3-cyano-5-oxo-4-substitutedaryl-4H-in-
deno[1,2b]-pyridine-1(5H)-yl]benzenesulfonamide
(6a-q)
Method (A): A mixture of
lidenemalononitriles 4a (0.01 mol) in ethanol (30
mL), containing 3 drops of triethylamine, was refluxed 4-[2-Amino-3-cyano-5-oxo-4-(4-hydroxyphenyl)-
for 4 h. The reaction mixture was filtered while hot -indeno[1,2- ]pyridin-1-(5 )-yl]benzenesulfon-
and the obtained solid was crystallized from ethanol, amide (6d)
to give 6a
Yield, 63%; m.p. 95-97oC; IR (KBr, cm−1): 3410 (OH),
Method (B): A mixture of (3 g, 0.01 mol), malono- 3367, 3260, 3210 (NH2), 2164 (C N), 1685 (C=O), 1396,
nitrile (0.66 g, 0.01 mol) and aldehyde (0.01 mol) in 1168 (SO2). 1H-NMR (DMSO-d6):
4.4 [s, 1H, CH], 6.5
3 (3 g, 0.01 mol) and ary- 11.91. Found: C, 63.60; H, 3.50; N, 11.60.
-q
4H
b
H
-q.
3
≡
δ
ethanol (30 mL), containing 3 drops of triethylamine, [s, 2H, NH2 exchangeable with D2O], 7.0-7.8 [m, 14H,
was refluxed for 4 h. The reaction mixture was filtered Ar-H + SO2NH2], 8.3 [s, 1H, OH]. 13C-NMR (DMSO-d6):
while hot and the obtained solid was crystallized from 39.2, 56.0, 105.8, 114.5, 116.1, 119.6, 123.0, 126.9, 127.5,
ethanol, to give 6a
same Rf).
-q
(m.p and mixed m.p and the 128.9, 130.5, 131.7, 134.1, 135.1, 136.4, 137.5, 140.8,
154.5, 159.6, 162.3, 186.4. Anal. Calcd for C25H18N4O4S:
C, 63.82; H, 3.86; N, 11.91. Found: C, 63.60; H, 3.50;
4-[2-Amino-3-cyano-5-oxo-4-phenyl-4
] pyridin-1-(5 )-yl]-benzenesulfonamide (6a)
Yield, 79%; m.p. 179-181oC; IR (KBr, cm−1): 3436, 3344, E-4-[2-amino-3-cyano-5-oxo-4-styryl-4
3280 (NH2), 3067 (CH arom.), 2190 (C N), 1705 (C=O), ] pyridin-1-(5 )-yl]ben-zenesulfonamide (6e)
1373, 1152 (SO2). H-NMR (DMSO-d6):
4.3 [s, 1H, Yield, 71%; m.p. 124-126oC; IR (KBr, cm−1): 3390, 3343,
CH], 6.6 [s, 2H, NH2 exchangeable with D2O], 7.0-7.9 3310 (NH2), 3060 (CH arom.), 2940, 2860 (CH aliph.),
H-indeno[1,2- N, 11.60.
b
H
H-indeno[1,2-
≡
b
H
1
δ

Novel Indenopyridines as Anticancer Agents
989
1
2190 (C
(DMSO-d6):
2H, CH=CH], 6.8 [s, 2H, NH2 exchangeable with D2O], 4-[2-Amino-3-cyano-5-oxo-4-(4-N-dimethylphen-
7.3-7.5 [m, 15H, Ar-H + SO2NH2]. 13C-NMR (DMSO-d6): yl)-4
-indeno[1,2- ]pyridin-1-(5 )-yl]benzenesul-
27.6, 58.1, 104.0, 117.8(2), 119.2, 123.4, 125.7(2), 127.8, fonamide (6i)
129.0, 129.5(2), 129.7, 129.9(2), 130.6, 130.8, 131.3, Yield, 66%; m.p. 167-169oC; IR (KBr, cm−1): 3421, 3367,
135.1, 136.5, 136.9, 138.0, 146.1, 153.4, 168.8, 194.7. 3280 (NH2), 2920, 2816 (CH aliph.), 2210 (C N), 1701
MS m/z (%) 480 [M+] (4.3), 219 (100). Anal. Calcd for (C=O), 1375, 1188 (SO2). 1H-NMR (DMSO-d6):
3.0 [s,
≡
N), 1701 (C=O), 1349, 1153 (SO2). H-NMR H, 3.64; N, 11.24. Found: C, 62.40; H, 3.90; N, 11.60.
δ
3.8 [d, 1H, CH-4, = 7.2 Hz], 6.6-6.7 [m,
J
H
b
H
≡
δ
C27H20N4O3S: C, 67.48; H, 4.20; N, 11.66. Found: C, 6H, 2CH3], 4.9 [s, 1H, CH], 6.8 [s, 2H, NH2 exchange-
67.10; H, 4.50; N, 11.40.
able with D2O], 7.7-8.0 [m, 14H, Ar-H + SO2NH2]. 13C-
NMR (DMSO-d6): 38.9, 39.9, 62.9, 100.2, 115.4, 116.2,
119.7, 123.9, 128.6, 129.1, 130.2, 131.5, 133.5, 134.8,
136.9, 137.7, 141.4, 146.3, 151.7, 154.2, 162.1, 190.4.
Anal. Calcd for C27H23N5O3S: C, 65.17; H, 4.66; N,
4-[2-Amino-3-cyano-5-oxo-4-(2-methoxyphenyl)-4H-
indeno-[1,2-
b]pyridin-1-(5H)-yl]benzenesulfon-
amide (6f)
Yield, 88%; m.p. 208-210oC; IR (KBr, cm−1): 3407, 3345, 14.08. Found: C, 65.50; H, 4.30; N, 14.40.
3243 (NH2), 3066 (CH arom.), 2940, 2853 (CH aliph.),
1
2212 (C
(DMSO-d6):
2H, NH2 exchangeable with D2O], 7.0-7.9 [m, 14H, Ar- (6j)
H + SO2NH2]. 13C-NMR (DMSO-d6): 32.7, 56.0, 61.8, Yield, 72%; m.p. 160-161oC; IR (KBr, cm−1): 3370, 3352,
98.1, 116.9, 118.3, 119.3, 122.2, 123.7, 127.2, 128.4, 3225 (NH2), 3046 (CH arom.), 2213 (C N), 1702 (C=O),
4.4 [s, 1H,
≡
N), 1710 (C=O), 1368, 1191 (SO2). H-NMR 4-[2-Amino-3-cyano-5-oxo-4-(3-nitrophenyl)-4
H
-in-
δ
3.7 [s, 3H, OCH3], 4.4 [s, 1H, CH], 6.9 [s, deno-[1,2-
b
]pyridin-1-(5H)-yl]benzenesulfonamide
≡
1
129.2, 130.0, 130.6, 131.3, 135.7, 137.6, 140.1, 145.7, 1349, 1192 (SO2). H-NMR (DMSO-d6):
δ
152.4, 158.4, 168.6, 195.2. MS m/z (%) 484 [M+] (9.1), CH], 7.1 [s, 2H, NH2 exchangeable with D2O], 7.4-8.4
63 (100). Anal. Calcd for C26H20N4O4S: C, 64.54; H, [m, 14H, Ar-H + SO2NH2]. 13C-NMR (DMSO-d6): 39.1,
4.16; N, 11.56. Found: C, 64.70; H, 4.40; N, 11.20.
56.0, 95.5, 118.7, 119.7, 122.6, 124.1, 126.4, 128.6, 129.2,
129.6, 130.1, 130.9, 135.4, 136.0, 136.9, 139.2, 145.7,
4-[2-Amino-3-cyano-5-oxo-4-(4-methoxyphenyl)- 147.2, 147.7, 153.1, 168.7, 194.8. MS m/z (%) 499 [M+]
4
H
-indeno-[1,2-
fonamide (6g)
Yield, 78%; m.p. 230-232oC; IR (KBr, cm−1): 3472, 3344,
b
]pyridin-1-(5
H
)-yl]benzenesul-
(3.3), 63 (100). Anal. Calcd for C25H17N5O5S: C, 60.11;
H, 3.43; N, 14.02. Found: C, 60.40; H, 3.10; N, 14.30.
3300 (NH2), 3100 (CH arom.), 2920, 2840 (CH aliph.), 4-[2-Amino-3-cyano-5-oxo-4-(4-nitrophenyl)-4H-
1
2208 (C
(DMSO-d6):
2H, NH2 exchangeable with D2O], 7.0-8.0 [m, 14H, Ar- Yield, 83%; m.p. 123-125oC; IR (KBr, cm−1): 3410,
H + SO2NH2]. 13C-NMR (DMSO-d6): 39.3, 56.0, 61.8, 3380, 3344 (NH2), 3088 (CH arom.), 2212 (C
N), 1709
98.1, 116.1, 117.0, 118.5, 127.2, 128.4, 129.1, 130.0, (C=O), 1347, 1190 (SO2). 1H-NMR (DMSO-d6):
4.3 [s,
≡
N), 1706 (C=O), 1349, 1188 (SO2). H-NMR indeno-[1,2-
b]pyridin-1-(5H)-yl]benzenesulfon-
δ
3.8 [s, 3H, OCH3], 4.3 [s, 1H, CH], 6.9 [s, amide (6k)
≡
δ
130.7, 131.3, 135.7, 137.0, 139.1, 147.1, 153.0, 158.4, 1H, CH], 7.1 [s, 2H, NH2 exchangeable with D2O], 7.4-
168.6, 191.8. MS m/z (%) 484 [M+] (2.4), 44 (100). Anal. 8.3 [m, 14H, Ar-H + SO2NH2]. 13C-NMR (DMSO-d6):
Calcd for C26H20N4O4S: C, 64.45; H, 4.16; N, 11.56. 38.9, 57.8, 95.1, 115.5, 118.5, 123.4, 126.9, 128.3, 129.2,
Found: C, 64.10; H, 4.50; N, 11.30.
130.1, 131.2, 131.6, 134.3, 135.6, 139.2, 145.7, 146.6,
147.7, 153.0, 169.1, 194.8. MS m/z (%) 499 [M+] (0.49),
4-[2-Amino-4-(benzo[d][1,3]dioxol-5-yl)-3-cyano-5- 283 (100). Anal. Calcd for C25H17N5O5S: C, 60.11; H,
oxo-4 -indeno[1,2- ]-pyridin-1-(5 )-yl]benzene- 3.43; N, 14.00. Found: C, 59.80; H, 3.70; N, 13.70.
sulfonamide (6h)
Yield, 68%; m.p. 85.87oC; IR (KBr, cm−1): 3448, 3363, 4-[2-Amino-3-cyano-5-oxo-4-(2-chlorophenyl)-4
3232 (NH2), 2985, 2897 (CH aliph.), 2191 (C N), 1705 indeno-[1,2- ]pyridin-1-(5 )-yl]benzenesulfon-
(C=O), 1380, 1157 (SO2). 1H-NMR (DMSO-d6):
4.3 [s, amide (6l)
1H, CH], 6.1 [s, 2H, O-CH2-O], 6.3 [s, 2H, NH2 exchange- Yield, 69%; m.p. 146-148oC; IR (KBr, cm−1): 3344, 3310,
able with D2O], 7.0-7.7 [m, 13H, Ar-H + SO2NH2]. 13C- 3260 (NH2), 3064 (CH arom.), 2214 (C
N), 1711 (C=O),
NMR (DMSO-d6): 38.9, 61.8, 101.3, 102.3, 115.9, 116.0, 1368, 1189 (SO2), 736 (C-Cl). H-NMR (DMSO-d6):
H
b
H
H-
≡
b
H
δ
≡
1
δ
118.2, 118.6, 122.9, 124.8, 127.9, 128.5, 129.2, 130.7, 4.3 [s, 1H, CH], 7.1 [s, 2H, NH2 exchangeable with D2O],
133.7, 134.1, 135.8, 137.5, 146.5, 146.9, 148.9, 152.9, 7.4-8.0 [m, 14H, Ar-H + SO2NH2]. 13C-NMR (DMSO-
163.8, 195.1. Anal. Calcd for C26H18N4O5S: C, 62.64; d6): 31.9, 61.8, 98.2, 118.9, 119.0, 123.8, 127.1, 127.2,

990
M. M. Ghorab and M. S. Al-Said
1
127.5, 128.4, 129.1, 129.6, 130.7, 131.5, 134.2, 135.5, 2186 (C
137.1, 139.3, 143.6, 145.4, 153.0, 168.6, 194.8. MS m/z (DMSO-d6):
≡
N), 1701 (C=O), 1392, 1157 (SO2). H-NMR
δ 3.7 [s, 3H, OCH3], 4.0 [s, 1H, CH], 6.8 [s,
(%) 488 [M+] (2.4), 44 (100). Anal. Calcd for 2H, NH2 exchangeable with D2O], 7.0-8.3 [m, 16H, Ar-
C25H17ClN4O3S: C, 61.41; H, 3.50; N, 11.47. Found: C, H + SO2NH2]. 13C-NMR (DMSO-d6): 38.9, 55.5, 56.4,
61.10; H, 3.80; N, 11.70.
103.6, 104.7, 115.4, 116.1, 122.0, 123.7, 124.3, 124.9,
125.3, 125.6, 126.5, 127.6, 128.0, 128.7, 130.4, 132.2,
133.7, 135.3, 137.8, 140.7, 155.4, 158.5, 162.8, 193.8.
Anal. Calcd for C30H22N4O4S: C, 67.40; H, 4.15; N,
10.48. Found: C, 67.70; H, 4.50; N, 10.10.
4-[2-Amino-3-cyano-5-oxo-4-(2,4-dichlorophenyl)-
4
H
-indeno-[1,2-
fonamide (6m)
Yield, 88%; m.p. 142-144oC; IR (KBr, cm−1): 3380, 3344,
3290 (NH2), 3056 (CH arom.), 2193 (C
1370, 1153 (SO2), 734 (C-Cl). 1H-NMR (DMSO-d6):
[s, 1H, CH], 6.3 [s, 2H, NH2 exchangeable with D2O], (6q)
7.2-7.9 [m, 13H, Ar-H + SO2NH2]. 13C-NMR (DMSO-d6): Yield, 81%; m.p. 47-49oC; IR (KBr, cm−1): 3434, 3380,
31.3, 60.3, 95.6, 115.1, 119.7, 125.1, 127.7, 128.8, 129.1, 3290 (NH2), 2190 (C N), 1707 (C=O), 1390, 1158 (SO2).
129.8, 130.4, 131.7, 132.8, 133.8, 134.3, 135.5, 137.2, 1H-NMR (DMSO-d6):
4.1 [s, 1H, CH], 6.8 [s, 2H, NH2
b]pyridin-1-(5H)-yl]benzenesul-
≡
N), 1717 (C=O), 4-[2-Amino-3-cyano-4-(2-thienyl-1-yl)-5-oxo-4
H-in-
δ
4.3 deno-[1,2- ]pyridin-1-(5 )-yl]benzenesulfonamide
b
H
≡
δ
138.4, 142.4, 145.4, 153.1, 168.6, 195.7. MS m/z (%) 523 exchangeable with D2O], 7.0-7.9 [m, 13H, Ar-H +
[M+] (2.9), 159 (100). Anal. Calcd for C25H16Cl2N4O3S: SO2NH2]. 13C-NMR (DMSO-d6): 27.8, 56.8, 103.6, 116.9,
C, 57.37; H, 3.08; N, 10.70. Found: C, 57.70; H, 3.40; 117.4, 123.1, 123.3, 123.4, 124.1, 126.7, 128.3, 129.0,
N, 10.40.
132.5, 135.5, 137.0, 138.4, 143.5, 151.3, 169.1, 196.4.
Anal. Calcd for C23H16N4O3S2: C, 59.98; H, 3.50; N,
12.17. Found: C, 59.60; H, 3.20; N, 12.50.
4-[2-Amino-3-cyano-4-(2-hydroxynaphthalen-l-yl)-
5-oxo-4
sulfonamide (6n)
Yield, 76%; m.p. 177-179oC; IR (KBr, cm−1): 3410 (OH),
3360, 3344, 3320 (NH2), 3048 (CH arom.), 2192 (C
1708 (C=O), 1348, 1153 (SO2). 1H-NMR (DMSO-d6):
H-indeno[1,2-b]-pyridin-1-(5H)-yl]benzene-
In vitro cytotoxic screening
The cytotoxic activity of the newly synthesized com-
≡
N), pounds was evaluated in vitro, using the Sulfo-Rhoda-
δ
mine-B stain (SRB) assay by the method of Skehan et
4.1 [s, 1H, CH], 6.8 [s, 2H, NH2 exchangeable with D2O], al. (1990). The in vitro anticancer screening was done
7.0-7.9 [m, 16H, Ar-H + SO2NH2], 10.3 [s, 1H, OH]. 13C- by the pharmacology unit, at the National Cancer In-
NMR (DMSO-d6): 29.4, 56.7, 104.3, 116.6, 117.7, 118.7, stitute, Cairo University.
119.0, 122.0, 123.9, 125.0, 125.4, 126.3, 127.7, 128.0,
Cells were plated in 96-multiwell microtiter plate
128.3, 129.2, 130.2, 134.0, 135.7, 137.0, 137.1, 147.9, (104 cells/well) for 24 h, before treatment with the com-
152.1, 153.4, 162.2, 195.3. MS m/z (%) 520 [M+] (3.3), 63 pound (s) to allow the attachment of cells to the wall
(100). Anal. Calcd for C29H20N4O4S: C, 66.91; H, 3.87; of the plate. The tested compounds dissolved in DMSO
N, 10.76. Found: C, 66.60; H, 3.50; N, 10.40.
and diluted with saline to the appropriate volume.
Different concentrations of the compounds under test
4-[2-Amino-3-cyano-4-(2-methoxynaphthalen-1-yl)- (5, 12.5, 25, and 50
µg/mL) were added to the cell
5-oxo-4H-indeno[1,2-b]-pyridin-1-(5H)-yl]benzene-
monolayer. Triplicate wells were prepared for each
individual dose. Monolayer cells were incubated with
sulfonamide (6o)
Yield, 73%; m.p. 160-162oC; IR (KBr, cm−1): 3478, 3377, the compound(s) for 48 h, at 37oC, and in atmosphere
3342 (NH2), 3071 (CH arom.), 2960, 2840 (CH aliph.), of 5% CO2. After 48 h, cells were fixed, washed, and
1
2189 (C
(DMSO-d6):
≡
N), 1701 (C=O), 1348, 1150 (SO2). H-NMR stained for 30 min with 0.4% (wt/vol) with SRB dissolv-
δ
3.8 [s, 3H, OCH3], 4.0 [s, 1H, CH], 7.0 [s, ed in 1% acetic acid. Excess unbound dye was removed,
2H, NH2 exchangeable with D2O], 7.3-7.9 [m, 16H, Ar- by four washes, with 1% acetic acid and attached stain
H + SO2NH2]. MS m/z (%) 534 [M+] (6.2), 47 (100). was recovered with Tris-EDTA buffer. Color intensity
Anal. Calcd for C30H22N4O4S: C, 67.40; H, 4.15; N, was measured in an ELISA reader. The relation
10.48. Found: C, 67.70; H, 4.50; N, 10.10.
between surviving fraction and drug concentration is
plotted to get the survival curve for breast tumor cell
4-[2-Amino-3-cyano-4-(4-methoxynaphthalen-1-yl)- line, after the specified time (Skehan et al., 1990). The
5-oxo-4H-indeno[1,2-b]-pyridin-1-(5H)-yl]benzene- molar concentration required for 50% inhibition of cell
sulfonamide (6p)
viability (IC50) was calculated and the results are given
Yield, 78%; m.p. 101-103oC; IR (KBr, cm−1): 3441, 3356, in Table I.
3251 (NH2), 3066 (CH arom.), 2981, 2839 (CH aliph.),

Novel Indenopyridines as Anticancer Agents
991
Table I
.
In vitro cytotoxic activity of the newly synthesized compounds against human breast cancer cell line (MCF-7)
Compound concentration ( g/mL)
12.5 25
Surviving fraction (Means ± S.E.)a
µ
a
b
Compd.
No.
IC50
µ
IC50
M)
5
50
(
g/mL)
(
µ
Doxorubicin
0.1943 ± 0.11
0.5251 ± 0.11
0.3823 ± 0.08
0.5005 ± 0.09
0.2815 ± 0.04
0.2263 ± 0.02
0.8502 ± 0.10
0.3539 ± 0.03
0.6704 ± 0.10
0.3172 ± 0.06
0.5989 ± 0.09
0.6809 ± 0.05
0.6993 ± 0.03
0.5770 ± 0.04
0.6036 ± 0.10
0.2827 ± 0.07
0.6339 ± 0.05
0.3846 ± 0.10
0.6814 ± 0.06
0.1717 ± 0.02
0.3857 ± 0.02
0.1714 ± 0.03
0.4878 ± 0.08
0.1411 ± 0.08
0.1346 ± 0.04
0.6243 ± 0.03
0.2782 ± 0.06
0.1404 ± 0.03
0.1250 ± 0.07
0.2995 ± 0.08
0.2977 ± 0.06
0.2720 ± 0.01
0.4562 ± 0.08
0.3978 ± 0.03
0.2987 ± 0.07
0.3730 ± 0.02
0.2198 ± 0.03
0.1574 ± 0.04
0.1855 ± 0.01
0.3556 ± 0.04
0.1566 ± 0.07
0.3661 ± 0.07
0.1407 ± 0.01
0.1212 ± 0.02
0.3514 ± 0.03
0.2443 ± 0.03
0.1828 ± 0.04
0.0804 ± 0.09
0.2239 ± 0.07
0.2616 ± 0.04
0.2296 ± 0.02
0.3451 ± 0.03
0.3268 ± 0.04
0.3405 ± 0.02
0.3564 ± 0.06
0.1358 ± 0.04
0.1946 ± 0.02
0.2013 ± 0.03
0.1778 ± 0.01
0.1362 ± 0.03
0.1588 ± 0.02
0.1431 ± 0.01
0.1153 ± 0.02
0.2735 ± 0.01
0.2779 ± 0.05
0.1577 ± 0.03
0.0591 ± 0.03
0.2220 ± 0.02
0.1029 ± 0.02
0.2164 ± 0.04
0.1580 ± 0.01
0.3101 ± 0.03
0.3576 ± 0.06
0.3525 ± 0.03
0.0990 ± 0.03
0.1351 ± 0.03
2.97
5.72
4.40
4.60
3.30
2.04
4.26
3.98
10.90
3.64
12.00
8.90
14.40
9.52
15.10
3.56
15.40
3.92
11.20
5.40
19.06
9.68
9.82
7.02
4.34
8.86
8.22
22.52
7.08
24.14
17.82
28.86
19.50
28.87
6.84
28.84
7.34
24.45
3
6a
6b
6c
6d
6e
6f
6g
6h
6i
6j
6k
6l
6m
6n
6o
6p
6q
aEach value is the mean of three values ± S.E.; bIC50 value: concentration causing 50% inhibition of cell viability.
cyclization (Scheme 1).
The -Aryl-substituted benzenesulfonamide decreases
the nucleophilicity of the enaminone towards aryli-
. The base catalyst triethyl-
, which amine was required to generate the anion of the en-
carries a biologically active benzenesulfonamide moiety aminone , thus, facilitating the addition to the unsat-
at position-1, free amino group at position-2 and cyano urated nitriles 4a (Scheme 2). On the other hand,
group at position-3 (Scheme 1), to evaluate their anti- compounds 6a were unambiguously synthesized by
cancer activity. Enaminone derivatives are highly another route, which involves one-pot condensation of
reactive intermediates extensively used for synthesis the aldehyde, malononitrile and enaminone , in a
of heterocyclic compounds. Thus, condensation of indan- molar ratio (1:1:1) in refluxing ethanol that contains
1,3-dione with sulfanilamide yielded the corres- triethylamine, as catalyst. In this case, formation of
ponding 4-(3-oxo-3 -inden-1-yl-amino]benzenesulfon- compounds 6a is illustrated in terms of initial con-
amide . The structure of compound was confirmed densation of the appropriate aldehyde with malononi-
by elemental analysis and spectral data. The IR spec- trile affording the activated arylidenemalononitriles
RESULTS AND DISCUSSION
N
3
Chemistry
The aim of this work was the design and synthesis denemalononitriles 4a
-q
of some new series of indeno[1,2-b]pyridine 6a
-q
3
-q
-q
3
1
2
H
-q
3
3
1
trum revealed bands at 3345, 3330, 3300 cm− (NH, 4a
NH2), 1715 cm−1 (C = O), 1372, 1158 cm−1 (SO2). Also, lidenemalononitriles 4a
1H-NMR spectrum indicated the presence of signal at 6a exhibited bands at 3472-3225 cm−1 corresponding
10.5 ppm, which could be assigned to NH of the en- to (NH2), 2214-2164 cm−1 (C N), 1720-1684 cm−1 (C = O),
aminone . Treatment of the enaminone
, with aryli- 1392-1150 cm−1 (SO2).
denemalononitriles, 4a in the presence of catalytic
-
q
, followed by addition of the enaminone
3 to ary-
-q. The IR spectra of compounds
-q
≡
3
3
-q
amount of triethylamine, as a base catalyst, yielded the
corresponding 4-[2-amino-3-cyano-5-oxo-4-substituted-
In vitro cytotoxic screening
All the newly synthesized compounds were evalu-
aryl-4H-indeno[1,2-b]pyridine-1-(5H)-yl]benzenesulfon- ated for their in vitro cytotoxic activity against breast
amide 6a-q, via the formation of the intermediate cancer cell line (MCF 7), compared with that of doxo-
Michael type products, followed by intramolecular rubicin (CAS 23214-92-8), as the positive control.

992
M. M. Ghorab and M. S. Al-Said
Scheme 1. The formation of indenopyridine derivatives (6a-q)
Doxorubicin, which is one of the most effective anti- phenyl 6c with (IC50 value = 7.02
cancer agents, was used as the reference drug in this dioxol 6h with (IC50 value = 7.08
µ
M) > benzo[
M) > 4-methoxy-1-
M) > 2-meth-
M) > styryl 6e
M) > unsubstituted phenyl 6a
parameter calculated was IC50 value, which corres- with (IC50 value = 9.68 M) > 4-tolyl 6b with (IC50
ponds to the concentration required for 50% inhibition value = 9.82 M). The presence of 4-hydroxyphenyl at
of cell viability. 4-position of indenopyridine ring 6d, with cyano group,
d][1,3]
µ
study. The relationship between surviving fraction naphthalene 6p with (IC50 value = 7.34
and drug concentration was plotted to obtain survival oxyphenyl 6f with (IC50 value = 8.22
curve of breast cancer cell line (MCF 7). The response with (IC50 value = 8.86
µ
µ
µ
µ
µ
From these results (Table I), it can be seen that at 3-position increased the cytotoxic activity, which
despite the variation in biological activity between the showed a higher potency than the tested compounds
compounds, it was not very high-yet, as the following and more potency than the reference drug doxorubicin.
points can still be concluded.
These results exhibited the nature of substituent at
It is clear from the results that the comparison of C-4 of the indenopyridine ring, by 4-hydroxyphenyl,
cytotoxic of the indenopyridine derivatives has shown has an important role on the cytotoxic activity and
the cells killing potency, which follows the order of in- potency.
denopyridine 6d, having 4-hydroxyphenyl at 4-posi-
tion with (IC50 value = 4.34 M) > 2-hydroxyl-1-naph- which bears 2-hydroxy-1-naphthalene moiety at 4-
thalene 6n with (IC50 value = 6.84 M) > 2-hydroxy- position with (IC50 value = 6.84 M) is nearly as active
On the other hand the indenopyridine derivative 6n
,
µ
µ
µ

Novel Indenopyridines as Anticancer Agents
993
Scheme 2. Postulated mechanism for the formation of compounds (6a-q)
as Doxorubicin, and exhibited a higher potency than
the indenopyridine derivative 6p that carries 4-meth-
oxy-1-naphthalene moiety at the same position with
ACKNOWLEDGEMENTS
The authors are grateful to the sponsorship of the
Research Center, College of Pharmacy and the Dean-
ship of Scientific Research, King Saud University,
(IC50 value = 7.34
µM).
In addition, it was found that the indenopyridine 6a
,
carrying unsubstitutedphenyl at 4-position with (IC50 Riyadh, Saudi Arabia.
value = 9.68 M), revealed a higher potency than that
of 4-tolyl 6b with (IC50 value = 9.82 M). According to
these results, it was found that the tested compounds
6a-c 6e 6f 6h, and 6p exhibited a moderate activity
and was found to be less active than the reference
µ
µ
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