Synthesis and antitumor studies of novel benzopyrano-1,2,3-selenadiazole and spiro[benzopyrano]-1,3,4-thiadiazoline derivatives

Article abstract of DOI:10.1007/s00044-012-0201-0

A convenient and efficient synthetic protocol of new selenadiazole and thiadiazoline derivatives incorporating benzopyranone moiety from readily available starting materials was described. Reaction of different 2,2-dialkyl and 2,2-spirocycloalkyl dihydrobenzopyranones 1a-e with semicarbazide hydrochloride and thiosemicarbazide afforded the corresponding semicarbazones 2a-e and thiosemicarbazones 3a-e, respectively. Furthermore, cyclization of the semicarbazones 2a-e via oxidation using selenium dioxide gave a novel series of chromenoselenadiazoles 4a-e. A series of spirobenzopyrano-1,3,4-thiadidazolines 5a-e were synthesized by refluxing of the thiosemicarbazones 3a-e in acetic anhydride. The synthesized compounds were tested in vitro against four cancer cell lines namely: MCF-7, VERO, WI-38, and HEPG-2. In vivo studies were also performed using Ehrlich ascites carcinoma for antitumor activity. Interestingly, Compounds 4b and 5a showed significant antitumor activities and were capable to improve the hematological parameters as well as increase the mean survival time of the mice bearing tumor.

Full text of DOI:10.1007/s00044-012-0201-0

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-012-0201-0
ORIGINAL RESEARCH
Synthesis and antitumor studies of novel benzopyrano-1,2,3-
selenadiazole and spiro[benzopyrano]-1,3,4-thiadiazoline
derivatives
•
S. I. El-Desoky F. A. Badria M. A. Abozeid
•
•
•
E. A. Kandeel A. H. Abdel-Rahman
Received: 21 April 2012 / Accepted: 9 August 2012
ꢀ Springer Science+Business Media, LLC 2012
Abstract A convenient and efficient synthetic protocol of
new selenadiazole and thiadiazoline derivatives incorporating
benzopyranone moiety from readily available starting mate-
rials was described. Reaction of different 2,2-dialkyl and
2,2-spirocycloalkyl dihydrobenzopyranones 1a–e with
semicarbazide hydrochloride and thiosemicarbazide afforded
the corresponding semicarbazones 2a–e and thiosemicarba-
zones 3a–e, respectively. Furthermore, cyclization of the
semicarbazones 2a–e via oxidation using selenium dioxide
gave a novel series of chromenoselenadiazoles 4a–e. A series
of spirobenzopyrano-1,3,4-thiadidazolines 5a–e were syn-
thesized byrefluxing of the thiosemicarbazones3a–e in acetic
anhydride. The synthesized compounds were tested in vitro
against four cancer cell lines namely: MCF-7, VERO, WI-38,
and HEPG-2. In vivo studies were also performed using
Ehrlichascitescarcinomaforantitumoractivity. Interestingly,
Compounds 4b and 5a showed significant antitumor activities
and were capable to improve the hematological parameters as
well as increase the mean survival time of the mice bearing
tumor.
Keywords Benzopyranone ꢀ
Chromeno-1,2,3-selenadiazole ꢀ 1,3,4-Thiadiazoline ꢀ
Antitumor activity
Introduction
Substituted benzopyran-4-ones are common among natural
products and they have been used to prepare various het-
erocyclic ring systems. On the other hand, the interesting
pharmacological activities of selenium heterocycles are
well known (Gleiter and Schehlmann, 1990; Lalezari et al.,
1974). In addition, selenium is a key component of several
major metabolic pathways in human, including thyroid
hormone metabolism, antioxidant defense system, and
immune function (Chen et al., 2009). Also, selenium sup-
plementation could reduce the incidence of various cancer
types such as prostate, lung, colon, and liver cancers (Chen
et al., 2009; El-Bayoumy and Sinha, 2004).
It is well known that a number of heterocyclic compounds
containing nitrogen and sulfur heteroatoms exhibited a wide
variety of biological activities (Ellis, 1977; Joshi et al., 2006;
Sharma and Sarita, 1994). Moreover, the diazole system is
found in numerous antiparasitic, fungicidal, and anti-
inflammatory drugs (Baht et al., 2005). Some 1,2,3-selena
and 1,3,4-(thia)diazoles were found to possess antitumor
activity (Klayman and Gunther, 1972; Atta et al., 2010).
In view of remarkable pharmacological efficiency of sel-
enadiazole and thiadiazoline derivatives and in continuation of
our studies in the chemistry of chromones (Atta et al., 2010;
El-Desoky et al., 1997; Abdel-Rahman et al., 2005; El-Sub-
bagh et al., 2000; El-Shafei et al., 2009), we report herein the
synthesis of 1,2,3-selena and 1,3,4-(thia)diazoles incorporated
benzopyranone scaffold to be evaluated pharmacologically as
antitumor agents.
S. I. El-Desoky (&) ꢀ M. A. Abozeid ꢀ E. A. Kandeel ꢀ
A. H. Abdel-Rahman
Chemistry Department, Faculty of Science,
Mansoura University, Mansoura 35516, Egypt
e-mail: desoky199@yahoo.com
F. A. Badria
Pharmacognosy Department, Faculty of Pharmacy,
Mansoura University, Mansoura 35516, Egypt
123

Med Chem Res
Results and discussion
5a–d, they appeared in the 1H-NMR spectra at two different
chemical shifts within d = 2.37–2.65 and 3.28–3.61 ppm
with coupling constant 13.20–14.10 Hz. This marked differ-
ence between the chemical shifts not only results from the
inductive effect exerted by the heteroatoms, but also due to a
spatial effect probably exerted by the acetyl groups. The
1H-NMR of 5b obviously revealed the presence of two iso-
mers I and II (Fig. 1). The percentages of both isomers were
calculated according to the integration curves of –CH3 signal
in both of them. Depending upon the stereochemistry of iso-
mer II, methyl group attached to C-2 is in the same direction to
nitrogen atom attached to C-4, therefore its chemical shift
has a higher value (1.35 ppm) than that of the isomer I
(1.32 ppm). Moreover, the 13C-NMR spectrum of 5d con-
firmed the ring closure by the appearance of a signal at circa
75.86 ppmassignedtoC-2inthiadiazolinering, andsignalsof
carbonyl moieties incorporated in the molecule at d =
168.95, 169.61, and 170.21 ppm. The mass spectra of 5b and
5c showed the molecular ion peaks at m/z 405 (M?, 21.20 %)
and 417 (M?, 28.60 %), respectively, which are in agreement
with their molecular formula.
Chemistry
The naturally occurring 6-hydroxy-2,2-dimethyl-2,3-dihy-
drobenzopyran-4-one (1a), which was previously isolated
from Calea cuneifolia DC and Gynura elliplia, possesses
anti-platelet aggregation activity (Lourenco et al., 1981;
Lin et al., 2000). Also, some benzopyranone derivatives
were used as IKs-channel blockers (Gerlach et al., 2001). In
the present work, the latter interesting biogenetic chroma-
none as well as a series of other structurally related dialkyl
and spirocycloalkylchromanones are used as precursors for
the construction of novel benzopyranoselenadiazole and
spirobenzopyranothiadiazoline derivatives hoping to obtain
promising biologically active compounds.
Refluxing of 2,5-dihydroxyacetophenone with different
ketones namely: acetone, butanone, cyclopentanone, cyclo-
hexanone, or cycloheptanone in the presence of catalytic
amount of pyrrolidine (Kabbe and Widdig, 1982) gave a
quantitative yield of the naturally occurring 2,2-dimethyl-2,
3-dihydrobenzopyran-4-one (1a) and a series of the structur-
ally related derivatives 1b–e. The melting points and spectral
data of 1a–d are in agreement with the reported data (Tripathi
et al., 2009). The reaction of 1a–e with semicarbazide
hydrochloride inthe presenceofsodiumacetate and few drops
of glacial acetic acid gave the corresponding semicarbazones
2a–e. Also, the reaction of 1a–e with thiosemicarbazide led to
the formation of thiosemicarbazone derivatives 3a–e.
Antitumor studies
Antitumor screening test
The cytotoxic effects of the synthesized compounds against
four different cell lines: MCF-7 (cells from breast cancer),
VERO (African green monkey kidney cells), WI-38
(fibroblast cells), and HEPG-2 (hepatoma cells) were
evaluated using 5-fluorouracil (5-FU) as a reference cyto-
toxic drugs (Table 1). The results showed that compounds
2b, 3b, 4a, 4b, 4c, 5c, and 5d were comparable to that of
5-FU (positive control) while compound 5a is more cyto-
toxic agent than 5-FU (Table 1).
On the other hand, heating of compounds 2a–e with
equimolar amounts of selenium dioxide gave a series of
chromenoselenadiazole derivatives 4a–e, respectively. The
construction of chromenoselenadiazoles 4a–e was achieved
via cyclocondensation of semicarbazones 2a–e using sele-
nium dioxide in acetic acid (Lalezari et al., 1969). Moreover,
the reaction of thiosemicarbazone derivatives 3a–d with
acetic anhydride afforded the corresponding spirochroman-
4,50-D2-1,3,4-thiadiazoline derivatives 5a–d in very good
yields (Scheme 1). The construction of 1,3,4-thiadiazoline
ring is mostly achieved by heterocyclization of thiosemi-
carbazones by acylation with acid anhydrides or acid chlo-
rides (Kubota et al., 1980).
The result of antitumor screening allows the following
assumptions about the structure activity relationships
(SARs) of the synthesized compounds: (a) the cytotoxic
activity increases by transforming benzopyranones deriv-
atives 1a–c into their respective semicarbazones 2a–c and
thiosemicarbazones 3a–c (Dutta et al., 2005). (b) Further
enhancement of cytotoxic activity was obtained via trans-
formation of semicarbazones derivatives to corresponding
selenadiazole derivatives as demonstrated in conversion of
2a and 2b to corresponding 4a and 4b, respectively. These
results are in full agreement with the previous obtained
data on the role of synthetic selenadiazole derivatives in
induction of caspase- and P53-dependent apoptosis in
breast carcinoma cells (Chen et al., 2009). (c) The appre-
ciable cytotoxicity of thiadiazoline derivatives, especially
5a, may be correlated with the presence of thiadiazoline
moiety in their molecular structures and this is in agree-
ment with the reported results (Ying et al., 2007). (d) As
All of the synthesized compounds were established on
the basis of analytical and spectral data (C.f. Experimental
1
section). The H-NMR spectrum of 2b revealed the aro-
matic and methylene protons, in addition to protons of
NH2, NH, and OH which were exchangeable with D2O at d
6.42, 8.85, and 9.35, respectively. Additionally, the
1H-NMR spectra of 4a–e revealed the absence of methy-
lene protons of the chroman ring, in addition to the
exchangeable protons except hydroxyl group proton.
As a result of the diastereotopic nature of methylene pro-
tons related to the chroman ring of thiadiazoline derivatives
123

Med Chem Res
Scheme 1 Synthesis of
O
O
O
chromenoselenadiazoles 4a–e
and spirochroman-4,50-D2-
1,3,4-thiadiazolines 5a–d
R1
R2
HO
HO
CH3
OH
R1
R2
Pyrrolidine/EtOH
O
1a-e
Thiosemicarbazide
Semicarbazide.HCl
EtOH
Conc HCl
EtOH
AcONa
H
N
H
NH2
N
NH2
N
N
HO
S
HO
O
R1
R1
O
3a-e
O
R2
R2
2a-e
SeO2
AcOH
Ac2O
AcHN
N
N
N
N
Se
R1
R2
HO
S
AcO
Ac
R1
R2
1-5 a; R1= R2 = CH3
O
4a-e
b
; R1= CH3; R2= CH2CH3
c; R1; R2= (CH2)4
d; R1; R2= (CH2)5
O
5a-d
e
; R1; R2= (CH2)6
NH
NH
S
Ac
this work, the effect on the mean survival time (MST) and
consequently percentage increase in life span (%ILS) was
studied. Adult swiss female albino mice were chosen for in
vivo studies.
Ac
N
N
S
N
4
N
4
Ac
Ac
3
3
CH3
CH3
2
2
A comparison was made among five groups of mice
(n = 7) on the 14th day after incubation. The groups
comprised of: (1) normal mice, (2) control (EAC-bearing
mice), (3), (4), and (5) EAC-bearing mice treated for the
first 9 days with 5-FU, 4b, and 5a. The results of in vivo
study are shown in Table 2.
O
O
CH3
CH3
1
1
II (33.33%)
I (66.67%)
Fig. 1 Two isomers of 5b
the size of the aliphatic moiety increases, the cytotoxic
activity decreases, this may be due to the steric hindrance
which takes place by increasing of the side chain size (You
et al., 1998).
We may infer the following information from Table 2:
(a) In the fifth day after inoculation of Ehrlich cells in mice,
increase in body weight and ascites was observed clearly,
and also the mice became slow and inactive. (b) Mice
which received compounds 4b, 5a, and 5-FU did not show
observed manifestation of abdominal ascites. (c) Hemato-
logical parameters of EAC-bearing mice on the 14th day
showed significant changes when compared with normal
mice. (d) Mice treated with compounds 4b and 5a showed
a dramatic reduction to the total WBC and reciprocally an
increase in the hemoglobin content and RBCs even more
than those treated with 5-FU. (e) Mice treated with com-
pounds 4b and 5a showed a reduction of the tumor size
even when compared to 5-FU. (f) Mice treated with
In vivo study using Ehrlich ascites carcinoma
(EAC) assay
The promising results of compounds 4b and 5a in the
antitumor screening test prompted us to study the effect of
the above two compounds on the viability of EAC, in
addition to the effect on the hematological status including
hemoglobin (Hb), hematocrit (HCT), and white blood cells
(WBCs) on EAC-bearing mice. And as a continuation of
123

Med Chem Res
anticancer agents. However, further pharmacokinetics,
bioavailability, and preclinical studies will be conducted in
the near future.
Table 1 In vitro cytotoxicity of tested compounds on different cell
lines
Compound
IC50 (mM)
MCF-7
VERO
WI-38
HEPG-2
Conclusion
1a
1b
1c
0.41
0.15
0.64
0.09
1.51
0.15
0.07
0.11
0.07
1.12
0.14
0.06
0.10
1.34
1.62
0.06
0.06
0.06
0.12
1.49
0.03
1.01
0.05
0.08
0.02
0.42
0.15
0.74
0.09
1.32
0.17
0.05
0.09
0.08
1.13
0.15
0.06
0.09
0.84
1.44
0.05
0.06
0.06
0.10
1.19
0.03
0.63
0.04
0.08
0.05
0.43
0.15
0.51
0.21
1.43
0.14
0.07
0.10
0.16
1.12
0.12
0.06
0.10
1.12
1.51
0.07
0.05
0.07
0.11
1.61
0.03
0.84
0.04
0.08
0.02
0.48
0.15
0.46
0.19
1.45
0.12
0.06
0.10
0.15
1.12
0.14
0.06
0.10
0.82
1.44
0.06
0.05
0.06
0.09
1.15
0.03
0.62
0.05
0.07
0.07
The present study reports an efficient and convenient
synthesis of novel series of selenadiazoles 4a–e and
thiadiazolines 5a–e. The naturally occurring 6-hydroxy-2,
2-dimethyl-2,3-dihydrobenzopyran-4-one (1a) as well as a
series of other structurally related dialkyl and spiro-
cycloalkyl chromanones were used as starting materials.
The cytotoxic effects of the synthesized compounds against
four different human cell lines such as MCF-7, VERO,
WI-38, and HEPG-2 were evaluated. The results revealed
that, compounds 2b, 3b, 4a, 4b, 5c, and 5d were similar to
that of 5-fluorouracil (IC50: 0.02–0.07 mM). Whereas,
compound 5a (IC50 = 0.03 mM) is more cytotoxic than 5-
FU. Moreover, in vivo antitumor study using Ehrlich ascites
carcinoma (EAC) revealed that there are an improvement
in the hematological parameters of tumor-bearing mice,
decrease in the tumor volume, and increases in the life span
to higher extent comparedwith 5-FU. Finally, compounds 4b
and 5a might be used as potential anticancer agents.
1d
1e
2a
2b
2c
2d
2e
3a
3b
3c
3d
3e
4a
4b
4c
4d
4e
5a
5b
5c
Experimental
5d
5-FU
General
All melting points are uncorrected and were recorded on an
open glass capillaries using a Gallenkamp apparatus. The
IR spectra (m/cm-1) (KBr) were recorded on Perkin Elmer
Infrared Spectrophotometer Model 157. The 1H-NMR
spectra were run on Bruker AC 300 MHz Spectropho-
tometer. 13C-NMR spectra were recorded on JOEL (at
500 MHz) using TMS as an internal reference and CDCl3
and DMSO-d6 as solvents, and chemical shift (d) values are
IC50 inhibition concentration that reduce survival to 50 %, 5-FU
5-fluorouracil
compounds 4b and 5a exhibited an increase in the MST
and consequently improvement of the percentage increase
in life span (%ILS) over those treated with 5-FU.
The above-mentioned results lead to a conclusion that
compounds 4b and 5a might be considered as potential
Table 2 Effect of compounds 4b and 5a on hematological parameters, viability of EAC, MST, and %ILS
Groups
Hb
(12–16 g/dL)
HCT
(35.0–50.0 %)
WBCs
(4–11) 9 103 cm
Viability of Ehrlich
cells (106/mL)
MST
(survival/day)
%ILS
Normal
Control
5-FU
4b
13.90
8.70
53.60
35.50
42.30
43.70
45.00
8.40
38.60
13.80
11.50
12.80
–
–
–
220.00
123.00
107.00
110.00
9.10
15.70
15.80
18.10
–
10.00
10.50
11.90
72.53
73.63
98.90
5a
Normal test without EAC, Control test with EAC, 5-FU 5-fluorouracil, Hb hemoglobin, HCT hematocrit, WBCs white blood cells, MST mean
survival time, %ILS percentage increase in life span
123

Med Chem Res
recorded in ppm. The mass spectra (EI) were run at 70 eV
with JEOL JMS600 equipment. Elemental analyses (C, H,
and N) were carried out at the Microanalytical Center at
Cairo University, Egypt. The results were found to be in
good agreement with the calculated values. Follow-up of
the reactions was made by thin layer chromatography
(TLC) on Silica gel pre-coated aluminum sheets (type 60
F254, Merck, Darmstadt, Germany) and the spots were
detected by exposure to UV lamp at k254 nm.
m/cm-1 = 3425–3300 (OH, broad), 1668 (C=O), 1617 (Ar);
1H-NMR (CDCl3) d (ppm): 1.20–2.20 (m, 12H, 6 CH2), 2.72
(s, 2H, H-3), 5.70 (s, broad, 1H, OH, exchangeable with
D2O), 6.86 (d, 1H, H-8, J = 9 Hz), 7.06 (dd, 1H, H-7,
J = 3.3, 9 Hz), 7.33 (d, 1H, H-5, J = 3.3 Hz). Anal. Calcd.
for C15H18O3 (246.13): C, 73.15; H, 7.37 %. Found: C,
73.32; H, 7.46 %.
General procedure for the synthesis of 2,2-dialkyl
and (spirocycloalkyl) 2,3-dihydrobenzopyran-4-one
semicarbazones 2a–e
Synthesis
General procedure for the synthesis of (2,2-dialkyl)
and (spirocycloalkyl)benzopyranones 1a–e
A solution of 1a–e (10 mmol), semicarbazide hydrochlo-
ride (2.23 g, 20 mmol), dry sodium acetate (2 g) in dry
ethanol (20 mL), and a catalytic amount of glacial acetic
acid (1 mL) was refluxed with stirring for 1–5 h (TLC
control). The reaction mixture was poured onto crushed ice
after cooling. The formed precipitate was filtered off,
washed with water, dried, and recrystallized from ethanol
to give compounds 2a–e.
Equimolar amounts of 2,5-dihydroxyacetophenone (1.52 g,
10 mmol) and ketone derivatives (10 mmol) namely: ace-
tone, butanone, pentanone, hexanone, or heptanone in eth-
anol containing a catalytic amount of pyrrolidine (1 mL)
was added. The reaction mixture was refluxed for 10–15 h
(TLC control). The solvent was evaporated under reduced
pressure and dried well. The obtained residual syrup was
purified with column chromatography using petroleum
ether/ethyl acetate as eluent to give compounds 1a–e.
6-Hydroxy-2,2-dimethyl-2,3-dihydrobenzopyran-4-one
semicarbazone (2a) Yield (1.82, 73 %); yellow crystals;
m.p. 212–214 ꢁC; Melting point and spectral data were in
complete agreement with the published data (Quilico et al.,
1950).
6-Hydroxy-2,2-dimethyl-2,3-dihydrobenzopyran-4-one (1a)
Yield (1.48 g, 77 %); yellow needles; m.p. 140–141 ꢁC;
[petroleum ether/ethyl acetate 4:1]. Melting point and
spectral data were in complete agreement with the pub-
lished data (Gerlach et al., 2001; Tripathi et al., 2009).
2-Ethyl-6-hydroxy-2-methyl-2,3-dihydrobenzopyran-4-one
semicarbazone (2b) Yield (1.43 g, 70 %); pale yellow
crystals; m.p. 100–101 ꢁC; IR (KBr): m/cm-1 = 3444,
3330, 3316, 3226 (OH, NH, NH2), 1675 (C=O, amide),
1581 (Ar); 1H-NMR (DMSO-d6) d (ppm): 0.80 (t, 3H,
CH2CH3, J = 7.5 Hz), 1.17 (s, 3H, CH3), 1.51 (dq, 1H,
CHaCH3), 1.63 (dq, 1H, CHbCH3), 2.64 (s, 2H, H-3), 6.42
(s, 2H, NH2, exchangeable with D2O), 6.62 (d, 1H, H-8,
J = 9 Hz), 6.67 (dd, 1H, H-7, J = 2.7, 9 Hz), 7.37 (d, 1H,
H-5), 8.85 (s, broad, 1H, NH, exchangeable with D2O),
9.35 (s, broad, 1H, OH, exchangeable with D2O). Anal.
Calcd. for C13H17N3O3 (263.13): C, 59.30; H, 6.51; N,
15.96 %. Found: C, 59.54; H, 6.45; N, 15.69 %.
2-Ethyl-6-hydroxy-2-methyl-2,3-dihydrobenzopyran-4-one
(1b) Yield (1.43 g, 70 %); deep yellow crystals; m.p.
60–61 ꢁC; [petroleum ether/ethyl acetate 4:1]. Melting
point and spectral data were in complete agreement with
the published data (Tripathi et al., 2009).
6-Hydroxy-2,2-tetramethylene-2,3-dihydrobenzopyran-4-
one (1c) Yield (1.48 g, 68 %); pale yellow crystals; m.p.
118–120 ꢁC; [petroleum ether/ethyl acetate 4:1]. Melting
point and spectral data were in complete agreement with
the published data (Tripathi et al., 2009).
6-Hydroxy-2,2-tetramethylene-2,3-dihydrobenzopyran-4-
one semicarbazone (2c) Yield (2.53 g, 92 %); colorless
crystals; m.p. 103–104 ꢁC; IR (KBr): m/cm-1 = 3430,
3362, 3284–3217 (OH, NH, NH2), 1692 (C=O, amide),
6-Hydroxy-2,2-pentamethylene-2,3-dihydrobenzopyran-4-
one (1d) Yield (2.13 g, 92 %); yellow crystals; m.p.
116 ꢁC; [petroleum ether/ethyl acetate 4:1]. Melting point
and spectral data were in complete agreement with the
published data (Tripathi et al., 2009).
1
1583 (Ar); H-NMR (DMSO-d6) d (ppm): 1.70–1.90 (m,
8H, 4 CH2), 2.76 (s, 2H, H-3), 6.41 (s, 2H, NH2,
exchangeable with D2O), 6.60 (m, 2H, H-7 and H-8), 7.38
(d, 1H, H-5, J = 3 Hz), 8.88 (s, 1H, NH, exchangeable
with D2O), 9.31 (s, 1H, OH, exchangeable with D2O).
Anal. Calcd. for C14H17N3O3 (275.13): C, 61.08; H, 6.22;
N, 15.26 %. Found: C, 61.22; H, 6.41; N, 15.50 %.
6-Hydroxy-2,2-hexamethylene-2,3-dihydrobenzopyran-4-
one (1e) Yield (1.56 g, 64 %); faint orange crystals; m.p.
126 ꢁC; [petroleum ether/ethyl acetate 4:1]; IR (KBr):
123

Med Chem Res
6-Hydroxy-2,2-pentamethylene-2,3-dihydrobenzopyran-4-
one semicarbazone (2d) Yield (2.60 g, 90 %); pale yel-
low crystals; m.p. 188–190 ꢁC; IR (KBr): m/cm-1 = 3467,
3349–3261 (OH, NH, NH2), 1673 (C=O, amide), 1573
2-Ethyl-6-hydroxyl-3-methyl-2,3-dihydrobenzopyran-4-one
thiosemicarbazone (3b) Yield (2.09 g, 75 %); pale brown
crystals; m.p. 200–201 ꢁC; IR (KBr): m/cm-1 = 3424,
3363, 3276 (OH, NH, NH2), 1606 (C=N), 1197 (C=S);
1H-NMR (DMSO-d6) d (ppm): 0.90(t, 3H, CH3CH2,
J = 7.80 Hz), 1.18 (s, 3H, CH3), 1.54 (dq, 1H, CHaCH3),
1
(Ar); H-NMR (DMSO-d6) d (ppm): 1.20–1.80 (m, 10H, 5
CH2) 2.65 (s, 2H, H-3), 6.39 (s, 2H, NH2, exchangeable
with D2O), 6.64–6.67 (m, 2H, H-7 and H-8), 7.36 (d, 1H,
H-5, J = 2.10 Hz), 8.80 (s, broad, 1H, NH, exchangeable
with D2O), 9.36 (s, 1H, OH, exchangeable with D2O).
Anal. Calcd. for C15H19N3O3 (289.14): C, 62.27; H, 6.62;
N, 14.52 %. Found: C, 62.47; H, 6.81; N, 14.73 %.
1.65 (dq, 1H, CHbCH3), 2.74 (d, 1H, Ha-3, Jgem
=
17.10 Hz), 2.84 (d, 1H, Hb-3, Jgem = 17.10 Hz), 6.65 (d,
1H, H-8, J = 8.70 Hz), 6.70 (dd, 1H, H-7, J = 3,
8.70 Hz), 7.48 (d, 1H, H-5, J = 3 Hz), 7.85 (s, 1H, NH2,
exchangeable with D2O), 8.23 (s, 1H, NH2, exchangeable
with D2O), 8.90 (s, 1H, NH, exchangeable with D2O),
10.31 (s, 1H, OH, exchangeable with D2O). MS (EI,
70 eV) m/z (%) = 280 [M??1] (0.08), 279 [M?] (0.29),
278 [M?-1] (0.09), 160 (41), 137 (81), 64 (100). Anal.
Calcd. for C13H17N3O2S (279.10): C, 55.89; H, 6.13; N,
15.04; S, 11.48 %. Found: C, 55.72; H, 6.33; N, 15.18; S,
11.71 %.
6-Hydroxy-2,2-hexamethylene-2,3-dihydrobenzopyran-4-
one semicarbazone (2e) Yield (2.25 g, 74.3 %); pale red
crystals; m.p. 118 ꢁC; IR (KBr): m/cm-1 = 3465, 3390–
1
3200 (OH, NH, NH2), 1675 (amide), 1571 (Ar); H-NMR
(DMSO-d6) d (ppm): 1.36–1.80 (m, 12H, 6CH2), 2.71 (s,
2H, H-3), 6.40 (s, 2H, NH2, exchangeable with D2O), 6.70–
6.76 (m, 2H, H-7 and H-8), 7.20 (d, 1H, H-5, J = 3 Hz),
8.47 (s, broad, 1H, NH, exchangeable with D2O), 9.41 (s, 1H,
OH, exchangeable with D2O). MS (EI, 70 eV) m/z
(%) = 304 [M??1] (20.15), 303 [M?] (98.29), 302 [M?-1]
(7.60), 286 [M?–NH3] (49.15), 260 (68.57), 246 (100), 203
(68.35). Anal. Calcd. for C16H21N3O3 (303.16): C, 63.35; H,
6.98; N, 13.85 %. Found: C, 63.51; H, 6.87; N, 13.71 %.
6-Hydroxy-2,2-tetramethylene-2,3-dihydrobenzopyran-4-
one thiosemicarbazone (3c) Yield (2.32 g, 80 %); pale
yellow crystals; m.p. 233–234 ꢁC; IR (KBr): m/cm-1
=
3439, 3362, 3284 (OH, NH, NH2), 1607 (C=N), 1195
(C=S); 1H-NMR (DMSO-d6) d (ppm): 1.40–1.80 (m, 8H, 4
CH2), 2.92 (s, 2H, H-3), 6.64 (d, 1H, H-8, J = 9 Hz), 6.72
(dd, 1H, H-7, J = 3, 9 Hz), 7.49 (d, 1H, H-8, J = 3 Hz),
7.86 (s, 1H, NH2, exchangeable with D2O), 8.23 (s, 1H,
NH2, exchangeable with D2O), 8.91 (s, 1H, NH,
exchangeable with D2O), 10.28 (s, 1H, OH, exchangeable
with D2O). Anal. Calcd. for C14H17N3O2S (291.10): C,
57.71; H, 5.88; N, 14.42; S, 11.00 %. Found: C, 57.82; H,
5.94; N, 14.34; S, 11.20 %.
General procedure for the synthesis of 2,2-dialkyl
and (spirocycloalkyl) 2,3-dihydrobenzopyran-4-one
thiosemicarbazones 3a–e
A mixture of chromanones 1a–e (10 mmol), thiosemicar-
bazide (1 g, 11 mmol) in dry ethanol (25 mL), and a cat-
alytic amount of conc. HCl (1 mL) was refluxed with
stirring for 3–5 h (TLC control). The reaction mixture was
cooled, poured onto crushed ice (100 g) thereafter, while
stirring was continued for 1 h. The formed precipitate was
filtered off, washed well with cold water, dried, and
recrystallized from ethanol to give compounds 3a–e.
6-Hydroxy-2,2-pentamethylene-2,3-dihydrobenzopyran-4-
one thiosemicarbazone (3d) Yield (2.44 g, 80 %); yellow
crystals; m.p. 122 ꢁC; IR (KBr): m/cm-1 = 3422, 3298–
1
3200 (OH, NH, NH2), 1589 (C=N), 1208 (C=S); H-NMR
(CDCl3) d (ppm): 1.34–1.97 (m, 10H, 5CH2), 2.56 (s, 2H,
H-3), 6.45 (s, broad, 3H, NH, NH2, exchangeable with
D2O), 6.80 (d, 1H, H-8), 7.25 (dd, 1H, H-7), 7.35 (d, 1H,
H-5), 8.77(s, broad, 1H, OH, exchangeable with D2O).
Anal. Calcd. for C15H19N3O2S (305.12): C, 58.99; H, 6.27;
N, 13.76; S, 10.50 %. Found: C, 58.71; H, 6.41; N, 13.90;
S, 10.69 %.
6-Hydroxy-2,2-dimethyl-2,3-dihydrobenzopyran-4-one thi-
osemicarbazone (3a) Yield (1.86 g, 70 %); yellow crys-
tals; m.p. 238–239 ꢁC; IR (KBr): m/cm-1 = 3426, 3351,
1
3270 (OH, NH, NH2), 1606 (C=N), 1197 (C=S); H-NMR
(DMSO-d6) d (ppm): 1.27 (s, 6H, 2 CH3), 2.81 (s, 2H, H-3),
6.63 (d, 1H, H-8, J = 9 Hz), 6.74 (dd, 1H, H-7, J = 2.70,
9 Hz), 7.49 (d, 1H, H-5, J = 2.70 Hz), 7.86 (s, 1H, NH2,
exchangeable wtih D2O), 8.24 (s, 1H, NH2, exchangeable
wtih D2O), 8.90 (s, 1H, NH, exchangeable wtih D2O), 10.22
(s, 1H, OH, exchangeable wtih D2O). Anal. Calcd. for
C12H15N3O2S (265.09): C, 54.32; H, 5.70; N, 15.84; S,
12.08 %. Found: C, 54.50; H, 5.88; N, 15.57; S, 12.27 %.
6-Hydroxy-2,2-hexamethylene-2,3-dihydrobenzopyran-4-
one thiosemicarbazone (3e) Yield (2.23 g, 70 %); yel-
low crystals; m.p. 184 ꢁC; IR (KBr): m/cm-1 = 3415,
3320, 3276 (OH, NH, NH2), 1594 (C=N), 1218 (C=S); 1H-
NMR (DMSO-d6) d (ppm): 1.20–1.90 (m, 12H, 6 CH2),
2.83 (s, 2H, H-3), 6.60–6.80 (m, 2H, H-7, H-8), 7.46 (d,
1H, H-5, J = 2.70 Hz), 7.84 (s, 1H, NH2, exchangeable
with D2O), 8.22 (s, 1H, NH2, exchangeable with D2O),
123

Med Chem Res
8.88 (s, broad, 1H, NH, exchangeable with D2O), 10.37 (s,
1H, OH, exchangeable with D2O). Anal. Calcd. for
C16H21N3O2S (319.14): C, 60.16; H, 6.63; N, 13.16; S,
10.04 %. Found: C, 60.41; H, 6.83; N, 13.37; S, 10.21 %.
m/cm-1 = 3448 (OH, free), 3500–3200 (OH, broad, bon-
ded), 1503 (N=N); 1H-NMR (DMSO-d6) d (ppm): 1.80–2.38
(m, 8H, 4 CH2), 6.72 (dd, H-7, J = 3 Hz, 8.70 Hz), 6.86 (d,
1H, H-6, J = 8.70 Hz), 7.43 (d, 1H, H-9, J = 3 Hz), 9.34 (s,
1H, OH, exchangeable with D2O). MS (EI, 70 eV) m/z
(%) = 309 [M??2] (6.66), 308 [M??1] (47.25), 307 [M?]
(4.01), 279 [M?–N2] (5.66), 251 (37.62), 199 (100), 115
(54.41). Anal. Calcd. for C13H12N2O2Se (308.01): C, 50.83;
H, 3.94; N, 9.12 %. Found: 50.91; H, 3.74; N, 9.10 %.
General procedure for the synthesis of 4,4-dialkyl
and (spirocycloalkyl)benzopyrano[4,3-d]
(1,2,3)selenadiazoles 4a–e
A solution of compounds 2a–e (5 mmol) in glacial acetic
acid (15 mL) was warmed at 60 ꢁC with stirring, then
selenium dioxide (0.55 g, 5 mmol) was added portionwise
during a period of 30 min and stirring was continued for
further 4–10 h (TLC control). After completion of the
reaction, the reaction mixture was filtered to remove the
deposited selenium. The filtrate was poured onto crushed
ice and the obtained solid was filtered off, washed thor-
oughly with cold water, sodium carbonate solution, and
water. The obtained product after drying was purified with
column chromatography using petroleum ether/ethyl ace-
tate as eluent to give compounds 4a–e.
8-Hydroxy-4,4-pentamethylene benzopyrano[4,3-d](1,2,3)sel-
enadiazole (4d) Yield (1.17 g, 73 %); yellow crystals;
m.p. 184 ꢁC; [petroleum ether/ethyl acetate 7:3]; IR (KBr):
m/cm-1 = 3378 (OH, free), 3530–3210 (OH, broad, bon-
1
ded), 1500 (N=N); H-NMR (DMSO-d6) d (ppm): 1.38–
2.20 (m, 10H, 5 CH2), 6.74 (d, 1H, H-7, J = 7.80 Hz), 6.93
(d, 1H, H-6, J = 8.70 Hz), 7.44 (s, 1H, H-9), 9.34 (s, 1H,
OH, exchangeable with D2O). Anal. Calcd. for
C14H14N2O2Se (322.02): C, 52.35; H, 4.39; N, 8.72 %.
Found: C, 52.10; H, 4.21; N, 8.42 %.
8-Hydroxy-4,4-hexamethylene benzopyrano[4,3-d](1,2,3)sel-
enadiazole (4e) Yield (1.24 g, 74 %); yellow crystals;
m.p. 144 ꢁC; [petroleum ether/ethyl acetate 7:3]; IR (KBr):
m/cm-1 = 3600–3200 (OH, broad, bonded), 1500 (N=N);
1H-NMR (DMSO-d6) d (ppm): 1.30–2.50 (m, 12H, 6CH2),
6.80–7.10 (m, 3H, H-7, H-6, H-9), 7.72 (s, 1H, OH,
exchangeable with D2O). Anal. Calcd. for C15H16N2O2Se
(336.04): C, 53.74; H, 4.81; N, 8.36 %. Found: C, 53.95;
H, 4.60; N, 8.40 %.
8-Hydroxy-4,4-dimethylbenzopyrano[4,3-d](1,2,3)selenadiaz-
ole (4a) Yield (1.04 g, 74 %); yellowish brown crystals;
m.p. 168–170 ꢁC; [petroleum ether/ethyl acetate 7:3]; IR
(KBr): m/cm-1 = 3500–3250 (OH, broad), 1502 (N=N);
1H-NMR (CDCl3) d (ppm): 1.77 (s, 6H, 2CH3), 5.35 (s,
broad, 1H, OH, exchangeable with D2O), 6.83 (dd, 1H, H-
7, J = 2.70, 8.70 Hz), 6.87 (d, 1H, H-6, J = 8.70 Hz),
7.79 (d, 1H, H-9, J = 2.70 Hz); 13C-NMR (CDCl3) d
(ppm): 30.39, 80.05, 111.58, 117.46, 118.52, 145.82,
151.09, 153.71, 159.60. Anal. Calcd. for C11H10N2O2Se
(281.99): C, 46.99; H, 3.58; N, 9.96 %. Found: C, 46.72;
H, 3.80; N, 9.76 %.
General procedure for the synthesis of spirochroman-4,
50-D2-1,3,4-thiadiazolines 5a–d
A mixture of 3a–d (10 mmol) in freshly distilled acetic
anhydride (20 mL) was refluxed on water bath (90 ꢁC) for
5–20 h (TLC control). After completion of the reaction, the
reaction mixture was poured onto crushed ice with vigor-
ous stirring. The formed precipitate was filtered off,
washed with water, dried, and purified by column chro-
matography using petroleum ether/ethyl acetate as eluent to
give compounds 5a–d.
4-Ethyl-8-hydroxy-4-methylbenzopyrano[4,3-d](1,2,3)sel-
enadiazole (4b) Yield (1.05 g, 71 %); yellow crystals;
m.p. 108 ꢁC; [petroleum ether/ethyl acetate 7:3]; IR (KBr):
1
m/cm-1 = 3400–3200 (OH, broad), 1504 (N=N); H-NMR
(CDCl3) d (ppm): 1.03 (t, 3H, CH3–CH2, J = 7.20 Hz), 1.72
(s, 3H, CH3), 2.02 (q, 2H, CH2–CH3, J = 7.20 Hz), 6.75–
6.90 (m, 3H, H-7, H-6, H-9), 7.77 (s, broad, 1H, OH,
exchangeable with D2O). MS (EI, 70 eV) m/z (%) = 297
[M??2] (12.59), 296 [M??1] (89.96), 295 [M?] (6.41), 294
[M?-1] (44.29), 267 [M?–N2] (24.72), 253 [M?–cyclo-
propane] (100), 188 [M?–selenadiazirene] (96.17), 173
(78.30), 131 (70.79). Anal. Calcd. for C12H12N2O2Se
(296.01): C, 48.82; H, 4.10; N, 9.49 %. Found: C, 48.96; H,
4.31; N, 9.63 %.
6-Acetoxy-40-acetyl-20-acetylamido-2,2-dimethylspirochro-
man-4,50-D2-1,3,4 thiadiazoline (5a) Yield (3.08 g, 70 %);
pale brown crystals; m.p. 144 ꢁC; [petroleum ether/ethyl
acetate 4:6]; IR (KBr): m/cm-1 = 3218 (NH), 1758 (CH3–
COO), 1702, 1680 (CH3CONH, two groups), 1621 (C=N).
1H-NMR (CDCl3) d (ppm): 1.34 (s, 3H, CH3), 1.46 (s, 3H,
CH3), 2.00 (s, 3H, CH3–COO–), 2.236 (s, 3H, CH3–CON),
2.243 (s, 3H, CH3–CON), 2.43 (d, 1H, Ha-3,
Jgem = 13.80 Hz), 3.42 (d, 1H, Hb-3, Jgem = 13.80 Hz), 6.73
(d, 1H, H-8, J = 8.70 Hz), 6.89 (dd, 1H, H-7, J = 3,
8-Hydroxy-4,4-tetramethylene benzopyrano[4,3-d] (1,2,3)sel-
enadiazole (4c) Yield (1.12 g, 73 %); yellow crystals; m.p.
144 ꢁC; [petroleum ether/ethyl acetate 7:3]; IR (KBr):
123

Med Chem Res
8.70 Hz), 7.13 (d, 1H, H-5, J = 3 Hz), 9.64 (s, br., 1H, NH,
exchangeable with D2O). Anal. Calcd. for C18H21N3O5S
(391.12): C, 55.23; H, 5.41; N, 10.73; S, 8.19 %. Found,
55.43; H, 5.21; N, 10.53; S, 8.00 %.
1756 (CH3COO), 1706, 1650 (CH3CONH, two groups), 1621
(C=N). 1H-NMR (CDCl3) d (ppm): 1.20–1.90 (m, 10H,
5CH2), 2.01 (s, 3H, CH3COO), 2.22 (s, 3H, CH3CON), 2.23
(s, 3H, CH3CON), 2.48 (d, 1H, Ha-3, Jgem = 14.10 Hz), 3.30
(d, 1H, Hb-3, Jgem = 14.10 Hz), 6.78 (d, 1H, H-8, J =
8.70 Hz), 6.90 (dd, 1H, H-7, J = 2.70, 8.70 Hz), 7.09 (d, 1H,
H-5, J = 2.70 Hz), 9.44 (s, 1H, NH, exchangeable with
D2O); 13C-NMR (CDCl3) d (ppm): 21.26, 21.50, 22.85,
24.32, 25.45, 32.65, 38.11, 45.30, 74.83, 75.86, 118.43,
120.03, 123.11, 125.38, 144.32, 145.52, 150.34, 168.95,
169.61, 170.21. Anal. Calcd. for C21H25N3O5S (431.15): C,
58.45; H, 5.84; N, 9.74; S, 7.43 %. Found: C, 58.25; H, 5.74;
N, 9.93, S, 7.33 %.
6-Acetoxy-40-acetyl-20-acetylamido-2-ethyl-2-methylspir-
ochroman-4,50-D2-1,3,4-thiadiazoline (5b) Yield (3.11 g,
77 %); yellow crystals; [petroleum ether/ethyl acetate 4:6];
m.p. 110 ꢁC; IR (KBr): m/cm-1 = 3222 (NH), 1760
(CH3COO), 1698, 1680 (CH3CON, two groups), 1621
(C=N). 1H-NMR (CDCl3) d (ppm): 1.00 (m, 6H, 2CH3CH2,
isomer I, II), 1.32 (s, 3H, CH3, isomer I), 1.35 (s, 3H, CH3,
isomer II), 1.55 (m, 2H, CH2CH3, isomer II), 1.75 (m, 2H,
CH2CH3, isomer I), 1.98 (s, 6H, 2CH3COO, isomer I, II),
2.25 (s, 12H, 4CH3CON groups, isomer I, II), 2.40 (d, 1H,
Ha-3, Jgem = 13.20 Hz, isomer I), 2.50 (d, 1H, Ha-3,
Jgem = 14.10 Hz, isomer II), 3.34 (m, 2H, Hb-3, isomer I, II),
6.71 (d, 2H, H-8, isomer I, II), 6.87 (m, 2H, H-7, isomer I, II),
7.12 (d, 2H, H-5, isomer I, II), 9.68 (s, 1H, NH, exchangeable
with D2O, isomer I), 9.85 (s, 1H, NH, exchangeable with
D2O, isomer II). MS (EI, 70 eV) m/z (%) = 407 [M??2]
(8.50), 406 [M??1] (17.80), 405 [M?] (21.20), 363 [M1,
M?–CH2CO], 304 [M2, M?–C3H4N2OS] (27.10), 293 [M3,
M1–CH2CO, CH2=CH2] (50.00), 262 [M4, M2–CH2CO]
(60.20), 251 [M3–CH2CO or CH3–CH=CH2] (85.60), 233
[M5–CH2CH2, H•] (100), 208 (43.20), 191 (37.30), 136
(24.60), 100 (20.30). Anal. Calcd. for C19H23N3O5S
(405.14): C, 56.28; H, 5.72; N, 10.36; S, 7.91 %. Found: C,
56.42; H, 5.93; N, 10.25; S, 7.70 %.
Antitumor studies
Antitumor screening test
Samples were prepared for assay by dissolving in 50 lL of
DMSO and diluting aliquots into sterile culture medium at
0.4 mg/mL. These solutions were subdiluted to 0.02 mg/mL
in sterile medium and the two solutions were used as stocks
to test samples at 100, 50, 20, 10, 5, 2, and 1 mg/mL in
triplicate in the wells of microtiter plates (El-Subbagh et al.,
2000).
The compounds were tested for cytotoxic activity
against MCF-7 (cells from breast cancer), VERO (African
green monkey kidney cells), WI-38 (fibroblast cells), and
HEPG-2 (hepatoma cells).
The compounds were assayed in triplicate on monolayers
grown in Dulbeccos modified Eagle’s medium supplemented
with 10 % (v/v) calf serum (HyClone Laboratories, Ogden,
UT), 60 mg/mL Penicillin G, and 100 mg/mL streptomycin
sulfate maintained at 37 ꢁC in a humidified atmosphere con-
taining about 15 % (v/v) CO2 in air. All medium components
were obtained from Sigma Chemical Co., St. Louis, MO,
unless otherwise indicated. Cells stocks were maintained at
34 ꢁC in culture flasks filled with medium supplemented with
1 % (v/v) calf serum. Subcultures of cells for screening were
grown in the wells of microtiter trays (Falcon Microtest III 96-
wells trays, Becton–Dickinson Labware, Lincolin Park, NJ)
by suspending cells in medium following trypsin–EDTA
treatment, counting the suspension with a hemocytometer,
diluting in medium containing 10 % calf serum to 2 9 104
cells per 200 mL culture, aliquoting into each well of a tray,
and culturing until confluent.
6-Acetoxy-40-acetyl-20-acetylamido-2,2-tetramethylenespirochro-
man-4,50-D2-1,3,4-thia-diazoline (5c) Yield (2.92, 70 %);
colorless crystals; m.p. 154–155 ꢁC; [petroleum ether/ethyl
acetate 4:6]; IR (KBr): m/cm-1 = 3218 (NH), 1762
(CH3COO), 1699, 1673 (CH3CONH, two groups), 1620
1
(C=N); H-NMR (CDCl3) d (ppm): 1.66–2.03 (m, 8H, 4
CH2), 2.09 (s, 3H, CH3COO), 2.24 (s, 3H, CH3CON), 2.27
(s, 3H, CH3CON), 2.37 (d, 1H, Ha-3, Jgem = 13.80 Hz),
3.61(d, 1H, Hb-3, Jgem = 13.80 Hz), 6.69 (d, 1H, H-8,
J = 9 Hz), 6.86 (d, 1H, H-7, J = 2.70, 9 Hz), 7.13 (d, 1H,
H-5, J = 2.70 Hz), 10.40 (s, 1H, NH, exchangeable with
D2O). MS (EI, 70 eV) m/z (%) = 418 [M??1] (6.60), 417
[M?] (28.60), 416 [M?-1] (19.80), 375 [M1, M?–CH2CO]
(52.7), 332 [M2, M1–Ac] (16.50), 316 [M2–O] (26.40), 293
[M3,
M1–cyclohexene],
251
[M3–CH2CO](100),
199(46.20), 115(30.80), 65(50.50). Anal. Calcd. for
C20H23N3O5S (417.14): C, 57.54; H, 5.55; N, 10.07; S,
7.68 %. Found: C, 57.74; H, 5.36; N, 10.27; S, 7.73 %.
Microtiter trays with confluent monolayer cultures of
cells were inverted, the medium shaken out, and replaced
with serial dilutions of sterile compounds in triplicate in
100 lL medium followed by titered virus in 100 lL medium
containing 10 % (v/v) calf serum in each well. In each tray,
the last row of wells was reserved for controls that were not
treated with compounds. The trays were cultured for 96 h.
6-Acetoxy-40-acetyl-20-acetylamido-2,2-pentamethylene-
spirochroman-4,50-D2-1,3,4-thiadiazoline (5d) Yield:
(4.09 g, 95 %); colorless crystals; m.p. 130 ꢁC; [petroleum
ether/ethyl acetate 4:6]; IR (KBr): m/cm-1 = 3224 (NH),
123

Med Chem Res
The trays were inverted onto a pad of paper towels, the
remaining cells rinsed carefully with medium, and fixed with
3.7 % (v/v) formaldehyde in saline for at least 20 min. The
fixed cells were rinsed with water and examined visually.
The cytotoxic activity is identified as confluent, relatively
unaltered monolayers of stained cells treated with com-
pounds. Cytotoxicity was estimated as the concentration that
caused approximately 50 % loss of the monolayer. 5-fluo-
rouracil was used as a positive control.
with LD50 value of 348.4 (303.4–401.1) mg kg-1 vs.
compound 4b which showed LD50 value of 247.1 (213.5–
286.1) mg kg-1
.
Effect of compounds 5a and 4b on hematological param-
eters In order to detect the influence of the tested com-
pounds on the hematological status of EAC-bearing mice, a
comparison was made among the groups of mice on the
14th day after inoculation. Blood was withdrawn from
each mouse from retro orbital plexus, and the white blood
cells (WBC) count, red blood cells (RBC) count, hemo-
globin, and HCT were determined.
In vivo study using EAC assay
Adult Swiss female albino mice (20–25 g) were purchased
from a local breeder and were housed in microlon boxes in
a controlled environment (temperature 25 ꢁC and 12 h
dark/light cycle) with standard laboratory diet and water
(El-Shafei et al., 2009).
Determination of viable cells count of EAC After 5 days
of treatment, 100 lL samples of EAC cells (from three
mice) were taken in each group, and 20-fold dilution in
saline was prepared. The cells were stained with trypan
blue and the viable cells were counted using a hemocy-
tometer. The mean value of total number of viable cells per
group (treated) was compared with those of the control
group.
Ascites fluid was withdrawn under aseptic conditions
from the peritoneal cavity of a EAC-bearing mouse (pur-
chased from National Cancer Institute, Cairo, Egypt) by
needle aspiration, and the EAC cells were suspended in
normal saline (0.9 % sodium chloride solution) so that each
0.2 mL contains 2 9 106 viable EAC cells and they were
microscopically examined for their viability using trypan
blue stain.
Effect of compounds 4b and 5a on survival time The
mean survival time (MST) of each group, consisting of
seven mice was noted. The antitumor efficacy was com-
pared with that of 5-FU, for 9 days. The MST of the treated
groups was compared with that of the control group using
the following calculation:
Mice were divided into five groups (7 each) as follows: (1)
normal mice, (2) control group (EAC only), (3) tumor-bearing
mice treated intraperitoneally (i.p.) with 5-fluorouracil
(20 mg/kg/day) as a standard anticancer drug dissolved
in saline (positive control), (4), and (5) tumor-bearing
mice treated intraperitoneally with the tested compounds
(50 mg/kg/day) suspended in saline. EAC cells suspension
(0.2 mL containing 2 9 106 cells per mouse) was inoculated
(i.p.) into the last four groups only. Twenty four hours after
inoculation, 100 lL of the treatment as a solution in saline
was injected (i.p.) into groups (3, 4, and 5) once a day for nine
consecutive days. The control group was treated with the
same volume of normal saline solution. The mice were
observed for 15 days. The activity was assessed using peri-
toneal cells count and hematological parameters.
Percentage increase in life span over control (%ILS) =
[MST of treated group - MST of control group] 9
100 - 100; where, MST = mean survival time (days of
each mouse in a group)/Total no. of mice (Sur and Ganguly,
1994).
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