Synthesis of new potential anticancer agents based on 4-thiazolidinone and oleanane scaffolds

Article abstract of DOI:10.1007/s00044-011-9893-9

The synthesis and evaluation of the anticancer activity of new acylated oximes derivatives of oleanolic acid with 4-thiazolidinone-3(5)-carboxylic acid moieties were described. Newly synthesized compounds were elucidated on the basis of elemental analyses

Full text of DOI:10.1007/s00044-011-9893-9

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2012) 21:3568–3580
DOI 10.1007/s00044-011-9893-9
ORIGINAL RESEARCH
Synthesis of new potential anticancer agents based
on 4-thiazolidinone and oleanane scaffolds
•
Danylo Kaminskyy Barbara Bednarczyk-Cwynar
•
•
Olexandr Vasylenko Oxana Kazakova Borys Zimenkovsky
•
•
•
Lucjusz Zaprutko Roman Lesyk
Received: 16 June 2011 / Accepted: 8 November 2011 / Published online: 25 November 2011
ꢀ Springer Science+Business Media, LLC 2011
Abstract The synthesis and evaluation of the anticancer
activity of new acylated oximes derivatives of oleanolic
acid with 4-thiazolidinone-3(5)-carboxylic acid moieties
were described. Newly synthesized compounds were elu-
cidated on the basis of elemental analyses and spectral data
Introduction
4-Azolidinone-3(5)-carboxylic acids represent one of the
most promising group among 4-azolidinone and related
derivatives with wide spectrum of pharmacological prop-
erties including anticancer effect (Lesyk and Zimenkovsky,
2004; Kaminskyy et al., 2009; Kaminskyy and Lesyk,
2010) which was realized via necroptosis inhibition (1)
(Teng et al., 2005), inhibition of Bcl-BH3 proteins inter-
action (2) (Degterev et al., 2001), JSP-1 (3) (Cutshall et al.,
2005) and farnesyl tranferase (4) (Lee et al., 2006) activ-
ities, etc. On the other hand, 4-azolidinone-3(5)-carboxylic
acids are attractive molecular fragments for different
scaffolds modification including linking with natural
compounds. Among the above-mentioned compounds,
b-amyrin triterpenoids, especially oleanolic acid (OA)
derivatives compose one of the most perspective group as
new lead-compound sources with anti-inflammatory (5)
(Honda et al., 2000a, b), antiviral (6) (Cichewicz and
Kouzi, 2004), antibacterial and anticancer (7) activities
(Honda et al., 2000a; Liby et al., 2007; Liu 2005; Couch
et al., 2005) (Fig. 1). Also, background for their utilization
is ability to activate the transdermal transport (Konoki and
Tachibana, 1996; Han et al., 1997). This aspect probably
can be used as an approach to design delivery systems
where triterpene fragment possesses not only specific
influence but also plays role of biologically active 4-thia-
zolidinone fragment transporter. Attempts to combine two
above-mentioned fragments into one molecule, as part of
‘‘double-drugs’’ creation, can be considered as hybrid
pharmacophore approach in drug-like substances design.
Its usage can increase the molecular fragments activities
level or the appearance of new type of activity and/or
improve the drug-like molecules characteristics. It is
known that modification of steroids anti-androgens A-ring
1
(IR, H, and 13C NMR). Anticancer activity of the tested
compounds has been evaluated in vitro at National Cancer
Institute (NCI) in which some structure activity relation-
ships (SARs) were discussed. Among the tested com-
pounds, 3-[(2,4-thiazolidinedione-5-ylidene)-carboxyimino]
olean-12-en-28-oic acid methyl ester (IVm) was superior
to other related compounds with mean values of pGI50
=
5.51/5.57, pTGI = 5.09/5.13, and pLC50 = 4.62/4.64, low
toxicity and moderate activity level in vivo hollow fiber
assay.
Keywords 4-Thiazolidinone-3(5)-carboxylic acids ꢀ
3-Hydroxyimino-oleananes ꢀ Anticancer activity
D. Kaminskyy ꢀ B. Zimenkovsky ꢀ R. Lesyk (&)
Department of Pharmaceutical, Organic and Bioorganic
Chemistry, Danylo Halytsky Lviv National Medical University,
Pekarska 69, Lviv 79010, Ukraine
e-mail: dr_r_lesyk@org.lviv.net; roman.lesyk@gmail.com
B. Bednarczyk-Cwynar ꢀ L. Zaprutko
Department of Organic Chemistry, Pharmaceutical Faculty,
Poznan University of Medical Sciences, Grunwaldzka 6,
60-780 Poznan, Poland
O. Vasylenko
Institute of Bioorganic Chemistry and Petrochemistry,
National Academy of Science of Ukraine, Murmanska 1,
Kyiv 02094, Ukraine
O. Kazakova
Institute of Organic Chemistry, Ufa Scientific Center, Russian
Academy of Sciences, pr. Oktyabrya 71, Ufa 450054, Russia
123

Med Chem Res (2012) 21:3568–3580
3569
by thia(oxa)zolidinone moiety led to identification of thia-
zole and oxazole derivatives as novel anti-androgens agents
(Mallarno et al., 1992). A unique class of 3-spirofused het-
erocyclic corticosteroids was developed as ‘‘soft drugs’’ by
the usage of the chemical delivery system approach (Bodor
1984). Cholesterylchloroformate was used for the alkylation
of potassium salt of 5-arylidene-2,4-thiazolidinediones in
the design of anticancer agents (Popov-Pergal et al., 2006) as
well as modification of OA leads to increasing of derivatives
activity levels (Liby et al., 2007; Dinkova-Kostova et al.,
2005; Finlay et al., 2002).
following points. OA derivatives with additional moiety in
position C-3 possess higher activity level that can be
related with structure of natural triterpenoids saponines
where sugar fragment is combined with C-3 atom. The
critical influence of double bond between C-3 and exocy-
clic nitrogen atom for anticancer activity achievement is
disclosed by following results of correlation between
structure of OA derivatives and their anticancer activities.
The presence of carboxylic group in C rings of triterpenes
increases biological activity as well (Zaprutko et al., 2004;
Ma et al., 2000; Chen et al., 2006).
Hence, in this article we aimed to synthesize new OA
derivatives with 4-thiazolidinone-carboxylic acids frag-
ments as new potential anticancer agents (Fig. 1).
Chemistry
Starting oximes (IIa–d) (Scheme 1) were synthesized by
reacting hydroxylamine hydrochloride with 3-oxooleanol-
ic acid (Ia), its methyl ester (Ib), morpholide (Ic), or
12-bromolactone (Id) in ethanol in the presence of anhy-
drous sodium acetate (Ma et al., 2000; Yasue et al., 1974).
The mentioned 3-oxooleananes (Ia–d) were obtained from
OA extracted from Viscum album L.
Results and discussion
The design of the target compounds is outlined in Fig. 1
and consists of modification of OA A-ring-linking group by
heterocyclic acids, with the usage of oxime function as a
link. The preliminary synthetic efforts were focused on C-3
and C-28 positions of OA modifications due to the
The synthesis of heterocyclic acids as starting com-
pounds was performed in several stages and is outlined in
Me
O
O
Me
OH
S
COOH
R1
O
R2
N
N
S
N
N
O
N
O
O
N
N
H
N
S
O
S
N
O
H
4
O
3
Ar
2
Et
1
Inhibitors of interaction
of Bcl-Xl and BH3 protein
Necroptosis inhibitors
Farnesyl tranferase inhibitor
JSP-1 inhibitors
COOH
O
O
O
O
OH
NC
O
OH
O
O
O
5
7
6
O
Anticancer and anti-inflammatory
agent (NO-depended mechanism)
O
Antimelanoma agent
Antiviral agent
O
Triterpene fragment -
Oleanolic acid derivatives
R1
R2
X = O, S; Y = (CH2)n
Y
N
S
X
Heterocyclic fragment -
4-thiazolidinonecarboxylic
Het
O
or
N
acids
O
O
A
Linker group
HN
O
S
A = single or double bond
Fig. 1 Structure of lead compounds belongs to 4-azolidinone and OA derivatives and background for target compounds synthesis
123

3570
Med Chem Res (2012) 21:3568–3580
Scheme 1 Synthesis of OA
3-hydroxyiminoderivatives with
different fragment at C-28
NH2OH*HCl
AcONa, EtOH
O
O
OH
OH
HO
N
O
IIa
Ia
NH2OH*HCl
AcONa, EtOH
O
O
O
O
Me
Me
HO
IIb
Ib
N
O
OA
O
O
NH2OH*HCl
AcONa, EtOH
N
O
N
O
HO
N
O
IIc
Ic
Br
Br
O
O
O
O
NH2OH*HCl
AcONa, EtOH
HO
IId
Id
N
O
1
Scheme 2. 5-Unsubstituted as well as 5-ethylrhodanine-3-
carboxylic acids (IIIa–d) were obtained via [2 ? 3]-cy-
clocondensation of dithiocarbaminates which were pre-
pared in situ and a-chlorocarboxylic acid (Yakubych and
Fedirko, 1983). The modification of core ring at C-5
position was achieved through Knoevenagel condensation
with aromatic aldehydes. 2,4-Thiazoliodinedione-5-car-
boxylic acids (IIIi, j) were synthesized based on maleic
anhydride in one phase method. It consisted in condensa-
tion reaction with further acid hydrolysis and bromination
in case of 2,4-dioxo-thiazolidin-5-ylidene-acetic acid (IIIj)
(Zimenkovsky et al., 2006; Deghengni and Daneault,
1960). 2,4-Thiazolidinedione-3-acetic acid (IIIg) was
synthesized by alkylation of 2,4-thiazolidinedione (Lesyk
et al., 2002).
The H NMR spectra display characteristic singlets of
triterpenes methyl groups at about 0.60–1.20 ppm and
signals of oxime group for compounds IIa–d in weak
magnetic field at about 8.0–10.0 ppm. Compounds IVa–
q were characterized by signals of oleanane and thiazole
fragments. Signals of exocyclic CH2 groups of 4-thiazoli-
dinone-3-carboxylic moieties (IVa–g) and aromatic pro-
tons (IVi, j) are presented in the classical manner.
Chemical shifts of methylidene group of 5-arylidene
derivatives (IVi, j) are shifted in weak magnetic field at
about 8.0 ppm. Also the CH group of 5-carboxymethylid-
ene fragment (IVm, o, q) showed a characteristic singlet at
about 8.00 ppm. Compounds with 4-thiazolidinone-5-ace-
tic (IVk, l, n, p) and 5-ethylrodanine fragments (IVb,
g) showed characteristic patterns of an AMX system of
CH2CH fragment as well as in case of simple 4-thiazo-
lidinone analogues (Kaminskyy et al., 2009).
For the synthesis of target 3-O-acyloleanolic acid
derivatives (IVa–q) the oximes IIa–d were acylated by
heterocyclic acids (IIIa–g) in the presence of N,N0-dicy-
clohexylcarbodiimide (DCC) (Scheme 3) in anhydrous
dioxane or THF at room temperature. The reactions were
monitored by TLC (benzene:AcOEt). Some of the obtained
compounds were purified by column chromatography. The
spectral data of newly synthesized compounds are pre-
sented in ‘‘Experimental’’ section. Analytical and spectral
data (IR, 1H NMR, 13C NMR, MS) confirmed the structure
of the synthesized compounds. Usage of simple aliphatic
acids in this reaction is one of the triterpenes structure
optimization successful methods in drug discovery (Ma
et al., 2000, 2002).
Biological activity
In vitro anticancer activity
The newly synthesized compounds as well as 3-oxoolean-
12-en-28-oic acid methyl ester (Ib) and 12a-bromo-3-
oxoolean-28b ? 13b olide (Id) were selected by National
Cancer Institute (NCI) Developmental Therapeutic Pro-
gram (www.dtp.nci.nih.gov) for in vitro cell line screening
to investigate their anticancer activity. Anticancer assays
were performed according to US NCI protocol, which was
123

Med Chem Res (2012) 21:3568–3580
3571
R1
-
-
-
X
CH2
(CH2)2
(CH2)5
CH2
OH
R
H
H
H
Et
-
OH
O
X
IIIa
IIIb
IIIc
IIId
IIIe
IIIf
O
X
N
a, b
X
O
c
O
N
O
H2N
H
R
S
R=H
S
S
O
-
S
IIIe,IIIf
MeO
Me2N
CH2
(CH2)2
IIIa-IIId
-
R1
O
O
S
O
O
O
H
N
H
OH
N
e
f
d
N
NH
O
O
IIIj
O
S
O
O
S
S
O
IIIg
IIIi
HO
O
HO
O
O
Scheme 2 Synthesis of starting heterocyclic carboxylic acids.
Reagents and condition: a amino acid (1.0 equiv), CS2 (1.0 equiv),
KOH (2.0 equiv), H2O, stirring, rt, 2 h; b 1 ClCHRCOOK (1.0 equiv),
H2O, stirring, rt, 24 h; 2 concentration HCl (2.5 equiv), heating, 90ꢁC,
2 h; c appropriate IIIa–d (1.0 equiv), ArCHO (1.0 equiv), AcONa
(1.0 equiv), AcOH, reflux, 5 h; d maleic anhydride (1.0 equiv),
thiourea (1.0 equiv), HCl, reflux, 3 h; e IIIi (1.0 equiv), Br2 (1.1
equiv), AcOH, reflux, 3 h; f 1 2,4-thiazolidinedione (1.0 equiv), KOH
(1.0 equiv), ClCH2COEt (1.0 equiv), EtOH, reflux, 3 h; 2 concen-
tartion HCl, reflux, 3 h
triterpene
fragment
IVa
IVb
IVc
IVd
IVe
IVf
IVg
IIa
IIa
IIb
IIb
IIb
IIb
IIb
X = CH2,
X = CH2,
X = CH2,
X = CH2,
X = (CH2)2, Y = S, R = H
X = (CH2)5, Y = S, R = H
Y = S, R = H
Y = S, R = Et
Y = S, R = H
Y = O, R = H
OH
O
O
X
N
O
X
N
O
N
H
R
O
H
R
Y
S
IVa - IVg
Y
X
X = CH2,
Y = S, R = Et
S
IIIa-IIId, IIIg
O
O
HO
N
N
O
IVi
IVj
IIb
IIb
X = CH2,
X = (CH2)2,
R1 = OMe
R1 = NMe2
X
N
N
IIa - IId
OH
O
S
O
S
IIIe, IIIf
S
S
DCC
IVi, IVj
R1
IVk
IVl
IIa
IIb
IIb
IIc
IIc
IId
IId
A = single bond
A = single bond
A = double bond
A = single bond
A = double bond
A = single bond
A = double bond
O
H
N
IVm
IVn
IVo
IVp
IVq
R1
O
A
O
O
O
S
O
S
N
A
HO
IIIi A = single bond,
IIIj A = double bond
N
H
O
Br
IVk - IVq
Structure of triterpene fragments
O
O
O
O
O
N
O
O
OH
Me
IIb
IId
IIa
IIc
Scheme 3 Synthesis of target 3-NO-acyl-oleanolic acid derivatives
described elsewhere (Monks et al., 1991; Boyd and Paull,
1995; Boyd, 1997; Shoemaker, 2006). The tested com-
pounds were first evaluated at one dose primary anticancer
assay towards approximately 60 cell lines (concentration
10-5 M). The human tumor cell lines were derived from
nine different cancer types: leukemia, melanoma, lung,
colon, CNS, ovarian, renal, prostate, and breast cancers. In
the screening protocol, each cell line was inoculated and
pre-incubated for 24–48 h on a microtiter plate. Test agents
were then added using single concentrations and the cul-
ture was incubated for a further 48 h. The end point
determinations were made with a protein binding dye,
sulforhodamine B (SRB). The results for each test agent
were reported as the percent growth of the treated cells
compared with the untreated control cells. The preliminary
screening results are shown in Table 1.
The tested compounds showed moderate potency of
anticancer activity but, have weak average values of anti-
cancer activity, possessed the significant specific influence
on some cancer cell lines even with stimulation influence on
cells growth (value of growth more than 100%). This activity
pattern appeared probably due to distinctive molecular
mechanisms of action for the mentioned substances and
feature of some cancer cell lines (www.dtp.nci.nih.gov;
123

3572
Med Chem Res (2012) 21:3568–3580
Table 1 Cytotoxic activity of the tested compounds in concentration 10-5 M against 60 cancer cell lines
Test
compounds
Mean Range of
Growth, % Growth, %
Most sensitive cell
Line growth, %
Ib
92.20
120.31
60.08
63.87–119.15 63.87 (SR/L); 85.25 (PC-3/PC); 75.65 (T-47D/BC)
Id
78.11–335.31 78.11 (K-562/L); 270.75 (SF-295/CNSC); 335.31(SK-OV-3/OC); 302.68 (COLO 205/CC)
IIb
-41.06–117.85 –41.06 (SR/L); (A549/ATTC/NSCLC); 44.14 (NCI-H460/NSCLC); 23.74 (NCI-H522/NSCLC);
3.39 (HCT-116/CC); 33.89 (U251/CNSC); 11.30 (OVCAR-8/OC); 26,08 (MCF-7/BC);
38.63 (PC-3/PC)
IId
75.84
-62.66–258.88 38.33 (RPMI-8226/L); 21.17 (K-562/L); 20,29 (MOLT-4/L); –62.66 (SR/L); 38.45 (PC-3/PC);
19.14 (SF-295/CNSC); 150.51 (A498/RC); 31.05 (TK-10/RC); 258.88 (HS 578T);
IVc
IVf
IVi
101.79
102.75
101.77
103.94
87.70
56.34–154.78 56.34 (CCRF-CEM/L);
42.83–178.01 76.91 (T-47D/BC); 42.83 (SR/L)
67.6–142.08 67.36 (BT-549/BC); 72.97 (SF-295/CNSC)
82.21–161.85 82.21 (IGROV1/OC)
IVj
IVk
IVm
37.86–183.59 54.55 (K562/L); 37.86 (RPMI-8226/L); 54.18 (SR/L);
73.35
-46.91–135.17 9.18 (T-47D/BC); –24.80 (CCRF-CEM/L); –46.91 (HL-60(TB)/L); 26.64 (K562/L);
2.28 (MOLT-4/L); 16.33 (RPMI-8226/L); –22.69 (SR/L);
IVn
82.02
81.40
120.34–21.46 29.41 (T-47D/BC); 42.47 (HL-60(TB)/L);
21.46 (RPMI-8226/L); 48.74 (SR/L);
IVq
24.85–150.58 24.85 (T-47D/BC); 26.14 (HL-60(TB)/L); 27.12 (K562/L); 26.82 (RPMI-8226/L); 29.41 (SR/L);
ColC colon cancer, M melanoma, NSCLC non-small cell lung cancer, RC renal cancer, CNSC CNS cancer, L leukemia, BC breast cancer, PC
prostate cancer, OV ovarian cancer
http://www.lgcpromochem-atcc.com). Comparison of dif-
ferent cancer cell lines sensitivity to the tested compounds
showed that leukemia panel is the most sensitive in all cases
except of compounds IVi and j. The influence on this panel
provided not only to increase of cell growth, but even to cell
death (growthpercent with negativevalue)and thisfactcan be
used for purposeful synthesis of antileukemic agents. Com-
pound IId possessed the most pronounced influence within
this panel. Among renal cancer panel the UO-31 line was the
most sensitive. Compounds IVm and n specifically restrained
the growth of this cancer lines (54.58 and 56.30 growth per-
cent, correspondingly) as well as PC-3 line to IId (38.63%).
The presence of an ylidene moiety in position C-5 of
thiazolidine ring played crucial role for anticancer activity
achievement of 4-thiazolidinone derivatives (Lesyk and
Zimenkovsky, 2004; Kaminskyy et al., 2009; Kaminskyy
and Lesyk, 2010). Comparison of IVc and i activity levels
which differed in the presence of the mentioned fragment did
not allowed us to determine significant difference as well as
in case of comparison of IVc and f activity which differs in
the amount of CH2 groups in carbon-chain of heterocyclic
fragments. Compounds with 2,4-dioxothiazolidin-5-ylide-
neacetic acid fragment (IVm and q) and different triterpene
moieties possessed the most prominent level of anticancer
activity and IVm possessed the strongest antimitotic effect
with significant influence on leukemia cell lines.
SARs features
Oximes IIb and d possessed higher activity level in com-
parison with appropriate 3-oxo-oleanane derivatives, which
had no anticancer activity and stimulated some cancer cell
line growth (Table 1). 4-Thiazolidinone derivatives pos-
sessed significant influence on non-small lung cancer
(NSLC) panel (Lesyk and Zimenkovsky, 2004; Kaminskyy
et al., 2009; Lesyk et al., 2006), but in our data only NCI-
H522 cell growth suppression was observed in comparison
with other lines of NSLC panel. However, compound IIb
visibly inhibited NCI-H522 and NCI-H460 cell lines
growth. Also, the T-47D (breast cancer panel) cell growth
was significantly suppressed by tested compound action in
comparison to another breast cancer cell lines.
In vitro full panel 60-cell line assay
Thus compounds IIb, d, and IVm were selected for
advanced assay and screened towards about 60 cell lines of
above-mentioned types of human cancers at five different
concentrations (10-4–10-8 M). A 48-h continuous drug
exposure protocol was used with SRB protein assay to esti-
mate cell viability and growth. Results (Table 2) are
expressed as log GI50, log TGI, log LC50 (GI50—molar
concentration of the compound that inhibits 50% netcell
growth; TGI—molar concentration of the compound leading
to total inhibition of cell growth; LC50—molar concentration
of the compound leading to 50% net cell death).
123

Med Chem Res (2012) 21:3568–3580
3573
Table 2 Anticancer activity of compounds IIb, d, and IVm
Cancer cell line
Dose-dependent parameters
pGI50
pTGI
pLC50
IVm*
IIb
IId
4.76
IVm*
IIb
4.09
IId
IVm*
IIb
Lukemia
CCRF-CEM
HL-60(TB)
K-562
5.76/5.61
5.82/5.69
5.74/5.56
5.73/5.68
5.73/5.63
5.77
4.55
4.23
4.43
4.43
4.40
4.57
4.54
4.55
4.67
4.72
4.56
4.70
4.14
4.66
4.58
4.65
4.64
4.53
4.62
4.64
4.41
4.70
4.62
4.75
4.68
4.59
4.74
4.72
4.71
–
5.43/5.11
5.46/5.27
5.37/5.09
5.37/5.13
5.34/5.22
5.41
\4.00
\4.00
\4.00
\4.00
\4.00
5.10
5.10/4.43
5.10/4.58
4.96/4.52
5.00/4.43
4.69/\4.00
5.05
\4.00
\4.00
\4.00
\4.00
\4.00
\4.00
\4.00
\4.00
4.03
\4.00
4.25
4.85
\4.00
5.67
4.75
4.04
4.39
5.36
4.55
4.42
4.70
4.72
–
\4.00
\4.00
\4.00
\4.00
4.26
MOLT-4
RPMI-8226
SR
Non-small cell
lung cancer
A549/ATCC
EKVX
5.34/5.46
5.17/5.52
4.70/4.97
5.73/5.81
4.91/5.71
5.55/5.47
4.74/4.89
5.54/5.69
5.74/5.69
5.58/5.75
5.46
4.75/4.84
4.65/5.03
4.44/4.64
5.33/5.39
4.51/5.34
5.07/4.91
4.49/4.58
5.02/5.21
5.38/5.25
5.27/5.45
4.91/5.52
5.47/5.50
4.96/4.96
5.33/5.29
5.12/4.90
5.41/5.48
4.97/5.27
4.72/4.68
5.50/5.44
4.58/4.66
4.64/4.85
5.47/5.47
5.51/5.53
5.11/5.41
5.29/5.36
5.04/5.16
5.36/4.75
5.42/5.45
4.75/4.81
4.74/4.61
4.99/5.01
–/5.38
\4.00
4.14
\4.00
\4.00
\4.00
4.33
4.21/4.39
4.25/4.31
4.19/4.31
\4.00/4.94
4.10/\4.00
4.38/4.40
4.23/4.27
4.39/4.77
5.03/4.59
4.80/5.15
4.37/5.21
5.19/4.21
4.19/4.41
5.01/4.80
4.53/4.44
5.12/5.18
4.38/4.73
4.30/4.26
5.22/5.12
4.25/4.33
4.31/4.42
5.17/5.19
5.18/5.23
4.33/5.10
4.70/-5.03
4.34/4.31
5.05/4.29
5.15/5.18
4.36/4.40
4.35/4.29
4.44/4.47
–/5.05
HOP-62
4.35
HOP-92
4.40
4.08
NCI-H226
NCI-H23
NCI-H322 M
NCI-H460
NCI-H522
COLO 205
HCC-2998
HCT-116
HCT-15
4.18
\4.00
\4.00
\4.00
\4.00
–
\4.00
4.13
4.42
\4.00
4.29
\4.00
\4.00
\4.00
\4.00
4.10
4.18
Colon cancer
4.04
4.09
4.72
4.51
4.75
5.05
5.17
4.56
4.85
4.70
4.27
4.69
4.65
5.00
5.52
5.04
–
4.24
\4.00
\4.00
\4.00
\4.00
\4.00
\4.00
\4.00
\4.00
4.44
4.37
5.75/5.78
5.59/5.56
5.65/5.66
5.55/5.46
5.70/5.77
5.50/5.67
5.36/5.31
5.78/5.75
4.91/4.98
4.97/5.51
5.77/5.75
5.84/5.83
5.64/5.73
5.64/5.69
5.55/5.62
5.66/5.34
5.69/5.73
5.28/5.39
5.22/4.94
5.72/5.65
–/5.72
4.25
\4.00
\4.00
\4.00
\4.00
4.08
4.26
HT-29
4.10
KM12
\4.00
4.39
SW-620
CNS cancer
SF-268
4.25
\4.00
4.11
SF-295
4.43
SF-539
4.38
\4.00
\4.00
4.22
4.09
SNB-19
4.16
\4.00
4.07
SNB-75
4.41
U251
4.47
\4.00
\4.00
4.63
4.21
Melanoma
LOX IMVI
MALME-3 M
M-14
4.40
4.08
–
\4.00
\4.00
\4.00
\4.00
\4.00
\4.00
\4.00
\4.00
\4.00
4.17
4.63
4.40
4.19
4.61
4.67
4.48
4.65
4.47
4.73
4.52
4.61
4.46
4.43
4.39
4.24
\4.00
–
MDA-MB-435
SK-MEL-2
SK-MEL-28
SK-MEL-5
UACC-257
UACC-62
IGROV1
OVCAR-3
OVCAR-4
OVCAR-5
OVCAR-8
NCI/ADR-RES
SK-OV-3
\4.00
\4.00
4.18
\4.0
4.36
4.58
4.83
4.73
–
\4.00
\4.00
\4.00
\4.00
\4.00
–
4.20
\4.00
4.25
Ovarian cancer
\4.00
4.45
5.72/5.78
5.60/5.63
4.73/4.78
5.66/5.45
5.12/5.36
4.70/4.87
4.94
4.94
\4.00
5.07
4.57
4.51
5.46/5.51
5.22/5.16
4.47/4.52
5.31/4.82
4.64/4.82
4.46/4.58
4.31
5.20/5.24
4.62/4.48
4.22/4.25
4.77/4.22
4.21/4.39
4.21/4.29
\4.00
4.26
\4.00
\4.00
4.27
\4.00
\4.00
\4.00
\4.00
\4.00
\4.00
\4.00
\4.00
\4.00
\4.00
123

3574
Med Chem Res (2012) 21:3568–3580
Table 2 continued
Cancer cell line
Dose-dependent parameters
pGI50
pTGI
pLC50
IVm*
IIb
IId
IVm*
IIb
4.46
IId
IVm*
IIb
4.18
Renal cancer
786-0
5.45/5.68
5.59/5.72
5.76/5.77
5.77/5.61
5.72/5.76
5.44/5.58
5.55/5.74
5.83/5.83
5.51/5.50
5.29/5.68
5.61/5.75
5.68/5.67
5.60/5.81
5.63/5.6o
5.37/5.57
5.70/5.66
5.51/5.57
4.75
4.55
4.68
4.71
4.74
4.68
4.47
4.65
4.69
4.69
4.69
4.69
4.56
4.19
4.60
–
4.31
4.94/5.32
5.24/5.33
5.47/5.49
5.45/4.79
5.45/5.48
4.73/5.05
5.09/5.32
5.53/5.53
4.95/4.85
4.77/5.34
4.97/5.37
5.12/5.16
5.17/5.20
5.22/5.04
4.73/4.85
5.35/5.18
5.09/5.13
\4.00
\4.00
\4.00
\4.00
–
4.44/4.90
4.75/4.85
5.18/5.21
5.13/4.26
5.18/5.19
4.10/4.24
4.40/4.76
5.24/5.24
4.33/4.43
4.37/4.98
4.35/4.95
4.38/4.41
4.39/4.38
4.63/4.34
4.15/4.33
4.99/4.56
4.62/4.64
A498
4.31
4.27
4.55
–
4.20
4.38
4.32
4.44
4.37
4.01
4.34
4.35
4.37
4.39
4.39
4.18
\4.00
4.14
–
\4.00
4.08
ACHN
CAKI-1
RXF 393
SN12C
\4.00
4.13
4.43
4.73
4.39
4.39
4.85
4.93
4.75
5.33
5.03
4.76
–
\4.00
4.28
4.06
TK-10
\4.00
4.02
UO-31
\4.00
\4.00
\4.00
4.22
PC
PC-3
4.01
DU-145
MCF7
4.05
Breast cancer
4.09
MDA-MB-231/ATCC
HS 578T
BT-549
T-47D
4.32
4.09
4.61
\4.00
\4.00
\4.00
–
4.16
4.13
MDA-MB-468
MID
–
4.57
4.65
4.21
4.09
4.03
* Data of repeat assay; pGI50 = -logGI50; pTGI = -log TGI; pLC50 = -log LC50; pLC50 values for IId \ 4.0
The values in Table 2 were calculated for each of these
parameters if the level of activity was reached; however, if
the effect was not reached or was exceeded, the value was
expressed as more or less than the maximum or minimum
concentration tested. Furthermore, mean graph midpoints
(MG_MID) were calculated for each of the parameters,
giving an average activity parameter over all cell lines for
each compound. For the calculation of the MG_MID,
insensitive cell lines were included with the highest con-
centration tested. The dose-dependent 60-cell line assay is
summarized in Table 2. The presented data showed that
compound IVm was characterized by the strong effect on
all cancer cell lines with insignificant selectivity to leuke-
mia cell lines (Fig. 2). Unsubstituted oximes (IIb,
d) showed weak levels of dose-depended parameters.
and compounds were administrated by ip route. The effects
of the compounds on reduction of viable cancer cell mass
compared with those of controls were determined. To
simplify evaluation, the NCI protocol adopts a point system
that allows rapid viewing of the activity of a given com-
pound. For this, a value of 2 is assigned for each compound
dose that results in a 50% or greater reduction in viable cell
mass. Compounds with a combined ip ? sc score C 20, a
sc score C 8, or a net cell kill of one or more cell lines
were considered significantly active. Compound IVm
exhibited ip score—8, sc score—16 and total score
(ip ? sc score) 16, with low cytotoxicity (no cell death).
Non-tumored animal toxicity assay for IVm was per-
formed according to NCI protocol (http://dtp.nci.nih.gov/
branches/btb/pdf/acutetox.pdf). The result shown the
maximum tolerated dose is more than 400 mg/kg. It can be
used to calculate the amount of material given to experi-
mental mice during further in vivo antitumor testing.
In vivo anticancer activity: hollow fiber assay
Compound IVm was found to have reproducible activity in
the in vitro anticancer drug screening which was evaluated
by NCI using hollow fiber assay. This assay provided
quantitative indications of the compound’s drug efficacy
COMPARE analysis
NCI web-resources allows to compare selectivity patterns
(mean graph fingerprints) of tested compounds with stan-
dard anticancer agents, NCI active synthetic compounds
and natural extracts, which are present in public available
data bases. Such analysis is based on the comparing the
patterns of differential growth inhibition for cultured cell
(http://dtp.nci.nih.gov/branches/btb/hfa.html)
(Plowman
et al., 1997; Hollingshead et al., 1995). In the hollow fiber
model, polyvinylidene fluoride fibers containing various
human cancer cell cultures were implanted intraperitone-
ally (ip) and subcutaneously (sc) into athymic nude mice
123

Med Chem Res (2012) 21:3568–3580
3575
action. On the other hand, if the activity pattern does not
correlate with any standard agent, it is possible that the
compound has a novel mechanism of action. Standard
COMPARE analyses (http://dtp.nci.nih.gov/docs/compare/
compare.html) (Zaharevitz et al., 2002) were performed at
GI50 level, obtained correlation coefficients (r) did not allow
to distinguish cytotoxicity mechanism of tested compounds
with high probability. Nevertheless moderate correla-
tions with fluorodopan (Nair et al., 1980) (NSC73754,
alkylating agent, r = 0.737), as well as with S-trityl-L-cys-
teine (NSC83265 r = 0.702)—aminoacyl-tRNA syntheta-
ses inhibitor with antiproliferative effect against leukemia
(Brier et al., 2004) were detected. Interesting, that other
4-azolidinone derivatives also have significant value of
correlation coefficients to the above-mentioned substance
(Havrylyuk et al., 2009; Subtel’na et al., 2010).
Conclusion
In the present article, 16 new acylated oximes of OA deriv-
atives with 4-thiazolidinone-3(5)-carboxylic acids frag-
ments were described. In vitro anticancer activity for
synthesized compounds as well as some chemical precursors
was evaluated. Obtained results confirmed availability of
combining oleanane and thiazolidinone scaffolds as direc-
tion of anticancer agent design. Among the tested com-
pounds, 3-[(2,4-thiazolidinedione-5-ylidene)-carboxyimino]
olean-12-en-28-oic acid methyl ester (IVm) was identified
as the most active substance with following values of dose-
depended parameters: pGI50 = 5.51/5.57, pTGI = 5.09/
5.13, and pLC50 = 4.62/4.64, low toxicity and moderate
activity level in vivo hollow fiber assay.
Experimental
Chemistry
The starting (2,4-dioxothiazolidin-5-yl)-acetic acid (IIIi)
(Zimenkovsky et al., 2006), 2,4-dioxothiazolidin-5-yli-
dene-acetic acid (IIIj) (Deghengni and Daneault, 1960),
rhodanine-3-carboxylic acids (IIIa–f) (Yakubych and
Fedirko, 1983), 2,4-dioxothiazolidin-3-acetic acid (IIIg)
(Lesyk et al., 2002) were obtained according to methods
described previously, as well as the 3-oxooleanolic acid
(Ia) (Shirane et al., 1996) and its metyl ester (Ib) (Ma
et al., 2000; Simonsen and Rossk, 1957), morpholide (Ic)
(Yasue et al., 1974) and 28b ? 13b lactone of 12a-bromo-
3-oxoolean-28-oic acid (Id) (Lewis and Tucker, 1983).
Melting points were measured in open capillary tubes on
a BUCHI B-545 melting point apparatus and are uncor-
rected. The elemental analyses (C, H, N) were performed
Fig. 2 Influence of IIb, d, and IVm on Leukemia panel cell lines,
corresponding
lines and can potentially gain insight into the mechanism of
the cytotoxic action. If the data pattern correlates well with
that of the compounds belonging to a standard agent
database (Pearson’s correlation coefficient (PCC) [ 0.6),
the compound of interest may have the same mechanism of
123

3576
Med Chem Res (2012) 21:3568–3580
using the Perkin–Elmer 2400 CHN analyzer and were
within 0.4% of the theoretical values. The IR spectra
were recorded using Specord IR–75 spectrophotometer, for
0.5% mixtures of tested compounds and KBr. The 1H- and
13C-NMR spectra were recorded on Varian Gemini
400 MHz or Bruker 125 MHz for frequencies, respec-
tively, 400 or 300 MHz and 100 or 75 MHz, in pyridine,
CDCl3, or DMSO-d6 using tetramethylsilane as internal
standard. The chemical shifts are reported in ppm with the
usage of d scale. Mass spectra were recorded using AMD
402 spectrophotometer with electroionisation.
(Yasue et al., 1974). Anal. calcd. for C34H54N2O3: C, 75.79;
H, 10.10; N, 5.20; Found: C, 76.00; H, 10.00; N, 5.35%.
12a-Bromo-3-hydroxyiminoolean-28b ? 13b olide (IId)
Yield 91%, mp 267–269ꢁC (lit. 251–252ꢁC (Simonsen and
Rossk, 1957). IR (m, cm-1): 3245 (OH, N–OH), 1770 (C=O,
lacton). 1H NMR (300 MHz, CDCl3) d: 0.90 (s, 3H, CH3),
0.98 (s, 3H, CH3), 1.00 (s, 3H, CH3), 1.07 (s, 3H, CH3), 1.17
(s, 3H, CH3), 1.25 (s, 3H, CH3), 1.43 (s, 3H, CH3), 2.36 (t,
1H, J = 4.5 Hz, C18–Hb), 4.30 (t, 1H, J = 1.9 Hz, C12–H),
8.50 (br.s, 1H, N–OH). 13C NMR (75 MHz, CDCl3) d: 178.8
(C-28), 166.8 (C-3), 91.6 (C-13), 56.2 (C-12), 45.5 (C-17).
DEPT: 7 9 CH3, 10 9 CH2, 4 9 CH, 30 9 C at. EI-MS
(m/z): 548.4 (9.8%) M?•. Anal. calcd. for C30H46BrNO3: C,
65.68; H, 8.45; N, 2.55; Found: C, 65.90; H, 8.60; N, 2.60%.
General procedure for synthesis of oleanolic acids
derivatives oximes (IIa–d)
Hydroxylamine hydrochloride (3.47 g, 50 mmol) was
added to appropriate 3-oxoolean derivative (I) (10 mmol)
in ethanol (50 ml), then anhydrous sodium acetate (6.56 g,
80 mmol) was added and the resulted mixture was refluxed
for 20–60 min (TLC control). After cooling reaction mix-
ture was diluted with water (300 ml) slightly acidified with
concentration HCl. The formed solid was filtered, washed
with water, and crystallized from ethanol to give IIa–d.
General procedure for synthesis of 4-thiazolidinone
substituted OA derivatives (IVa–q)
A mixture of appropriate 3-hydroxyiminoolean-derivative
(IIa–d) (2 mmol) and 4-thiazolidinone-carboxylic acid
(IIIa–g) (2.4 mmol) in dry dioxane was stirred at room
temperature to dissolution. DCC (0.619 g, 3 mmol) was
added to the reaction mixture, the stirring in room tem-
perature was continued until the triterpenic substrate con-
sumption (0.5–1.5 h, TLC control). The solid formed was
filtered and the filtrate was poured into of water (200 ml)
slightly acidified with concentration HCl. The formed solid
was filtered, washed with water and dried. The residue was
purified by column chromatography if necessary (Kisielgel
3-Hydroxyiminoolean-12-en-28-oic acid (IIa) Yield 90%,
mp 297–299ꢁC (lit. 291ꢁC (Simonsen and Rossk, 1957)). IR
(m, cm-1): 3350 (OH, COOH), 3240 (OH, N–OH), 1680
(C=O, COOH). 1H NMR (Ma et al., 2000). 13C NMR
(75 MHz, pirydine) d: 180.1 (C-28), 164.1 (C-3), 144.8 (C-
13), 122.4 (C-12), 46.6 (C-17). DEPT: 7 9 CH3, 10 9 CH2,
4 9 CH, 30 9 C at. EI-MS (m/z): 469.7 (5.6%) M?•. Anal.
calcd. for C30H47NO3: C, 76.71; H, 10.09; N, 2.98; Found: C,
77.00; H, 10.20; N, 3.10%.
60
(0.063–0.200 mm/70–230
mesh,
eluent–ben-
zene:AcOEt) and crystallized or precipitated with water
from ethanol.
3-(Rhodanine-3-acetyloxyimino)-olean-12-en-28-oic acid
(IVa) Yield 86%, mp 144–146ꢁC. IR (m, cm-1): 3400
(O–H, COOH), 1705 (C=O, thiazole), 1670 (C=O, COOH),
1625 (C=O, COON), 1505 (C=S, thiazole). 1H NMR
(400 MHz, DMSO-d6) d: 0.77 (s, 3H, CH3), 0.88 (s, 6H,
2 9 CH3), 0.98 (s, 3H, CH3), 1.09 (s, 3H, CH3), 1.10 (s,
3H, CH3), 1.17 (s, 3H, CH3), 2.74–2.84 (m, 1H, C18–H),
4.46 (s, 2H, CH2-thiazole), 4.85 (s, 2H, NCH2CO), 5.18
(br.s, 1H, C12–H), 11.96 (br.s, 1H, COOH), 13C NMR
(100 MHz, DMSO-d6) d: 203.1 (C=S), 179.0 (C-28), 176.7
(C=O, thiazole), 174.1 (C=O, COON), 165.3 (C-3), 144.4
(C-13), 121.9 (C-12), 46.3 (C-17). DEPT: 7 9 CH3,
12 9 CH2, 4 9 CH, 35 9 C at. Anal. calcd. for
C35H50N2O5S2: C, 68.39; H, 7.84; N, 4.36; Found: C,
68.50; H, 7.90; N, 4.50%.
3-Hydroxyiminoolean-12-en-28-oic acid methyl ester (IIb)
Yield 93%, mp 247–249ꢁC (lit. 254–255ꢁC (Simonsen and
Rossk, 1957). IR (m, cm-1): 3245 (OH, N–OH), 1720 (C=O,
1
COOCH3). H NMR (300 MHz, CDCl3) d: 0.76 (s, 3H,
CH3), 0.90 (s, 3H, CH3), 0.92 (s, 3H, CH3), 1.03 (s, 3H, CH3),
1.06 (s, 3H, CH3), 1.11 (s, 3H, CH3), 1.16 (s, 3H, CH3), 2.90
(dd, 1H, J1 = 4.0, 13.6 Hz; C18–Hb), 3.63 (s, 3H, COOCH3),
5.29 (t, 1H, J = 3.4 Hz; C12–H), 9.37 (s, 1H, N–OH). 13C
NMR (75 MH, CDCl3) d: 178.3 (C-28), 166.9 (C-3), 143.8
(C-13), 122.2 (C-12), 51.5 (C-31), 46.6 (C-17). DEPT:
8 9 CH3, 10 9 CH2, 4 9 CH, 31 9 C at. EI-MS (m/z):
483.0 (6.0%) M?•. Anal. calcd. for C31H49NO3: C, 76.97; H,
10.21; N, 2.90; Found: C, 77.10; H, 10.10; N, 2.80%.
3-Hydroxyiminoolean-12-en-28-oic acid morpholide (IIc)
Yield 87%, mp 206–211ꢁC (lit. 192–195ꢁC (Yasue et al.,
1974). IR (m, cm-1): 3250 (OH, N–OH), 1625 (C=O, amide),
995 (C–O, morph.). 1H NMR (Yasue et al., 1974). 13C NMR
3-(5-Ethylrhodanine-3-acetyloxyimino)-olean-12-en-28-
oic acid (IVb) Yield 95%, mp 102–109ꢁC. IR (m, cm-1):
3405 (O–H, COOH), 1700 (C=O, thiazole), 1675 (C=O,
123

Med Chem Res (2012) 21:3568–3580
3577
1
COOH), 1620 (C=O, COON), 1500 (C=S, thiazole). H
NMR (400 MHz, DMSO-d6) d: 0.76 (s, 3H, CH3), 0.88 (s,
6H, 2 9 CH3), 0.96 (s, 3H, CH3), 0.98 (s, 3H, CH3), 1.08
(s, 6H, 2 9 CH3), 1.10 (s, 3H, CH3), 1.17 (s, 3H, CH3),
2.00–2.08 (m, 2H, CH2CH-thiazole), 2.74–2.86 (m, 1H,
C18–H), 4.81–4.88 (m, 3H, CH2COO, Et–CH-thiazole),
5.18 (br.s, 1H, C12–H), 12.06 (br.s 1H, COOH). 13C NMR
(100 MHz, DMSO-d6) d: 202.0 (C=S), 179.0 (C-28), 176.7
(C=O, thiazole), 176.3 (C=O, COON), 165.3 (C-3), 144.4
(C-13), 121.8 (C-12), 46.9 (C-17). DEPT: 8 9 CH3,
12 9 CH2, 5 9 CH, 37 9 C at. Anal. calcd. for
C37H54N2O5S2: C, 66.23; H, 8.11; N, 4.17; Found: C,
66.39; H, 8.22; N, 4.30%.
4.14 (t, J = 7.4 Hz, 2H, NCH2CH2), 4.24 (s, 2H, CH2–
thiazol) 5.21 (br.s, 1H, C12–H). 13C NMR (100 MHz,
DMSO-d6) d: 201.5 (C=S), 177.8 (C-28), 175.5 (C=O, thi-
azole), 174.7 (C=O, COON), 169.2 (C-3), 144.1 (C-13).
122.4 (C-12), 52.1 (COOCH3), 46.7 (C-17). DEPT:
8 9 CH3, 13 9 CH2, 4 9 CH, 37 9 C at. Anal. calcd. for
C37H54N2O5S2: C, 66.23; H, 8.11; N, 4.17; Found: C, 66.40;
H, 8.23; N, 4.21%.
3-(Rhodanine-3-hexanoyloxyimino)-olean-12-en-28-oic acid
methyl ester (IVf) Yield 87%, mp 134–138ꢁC. IR (m,
cm-1): 1720 (C=O, COOCH3), 1695 (C=O, thiazole), 1640
1
(C=O, COON), 1500 (C=S). H NMR (400 MHz, DMSO-
d6) d: 0.69 (s, 3H, CH3), 0.88 (s, 6H, 2 9 CH3), 0.98 (s, 3H,
CH3), 1.07 (s, 3H, CH3), 1.10 (s, 3H, CH3), 1.16 (s, 3H, CH3),
1.42–1.62 (m), 1.98 (m), 2.24 (t, J = 7.2 Hz), 2.41 (t,
J = 7.2 Hz), 3.85 (t, J = 7.3 Hz) (10H, (CH2)5), 2.73–2.85
(m, 1H, C18–H), 3.55 (s, 3H, COOCH3), 4.25 (s, 2H, CH2-
thiazole), 5.21 (br.s, 1H, C12–H). 13C NMR (100 MHz,
DMSO-d6) d: 203.1 (C=S), 177.8 (C-28), 175.1 (C=O, thi-
azole), 171.3 (C=O, COON), 170.1 (C-3), 144.1 (C-13),
122.5 (C-12), 52.1 (COOCH3), 46.7 (C-17). DEPT:
8 9 CH3, 16 9 CH2, 4 9 CH, 40 9 C at. Anal. calcd. for
C40H60N2O5S2: C, 67.38; H, 8.48; N, 3.93; Found: C, 67.17;
H, 8.34; N, 4.19%.
3-(Rhodanine-5-acetyloxyimino)-olean-12-en-28-oic acid
methyl ester (IVc) Yield 90%, mp 128–130ꢁC. IR (m,
cm-1): 1720 (C=O, COOCH3), 1705 (C=O, thiazole), 1635
(C=O, COON), 1505 (C=O, thiazole). 1H NMR (300 MHz,
CDCl3) d: 0.76 (s, 3H, CH3), 0.90 (s, 3H, CH3), 0.93 (s,
3H, CH3), 1.03 (s, 3H, CH3), 1.13 (s, 6H, 2 9 CH3), 1.24
(s, 3H, CH3), 2.88 (dd, J1 = 4.2, 13.8 Hz, 1H, C18–H),
3.63 (s, 3H, COOCH3), 4.09 (s, 2H, CH2COON), 4.96 (s,
2H, CH2-thiazole), 5.29 (t, 1H, J = 3.6 Hz, C12–H). 13C
NMR (75 MHz, CDCl3) d: 200.1 (C=S), 178.0 (C-28),
175.9 (C=O, thiazole), 172.9 (C=O, COON), 165.5 (C-3),
143.8 (C-13), 121.9 (C-12), 51.6 (COOCH3), 46.7 (C-17).
DEPT: 8 9 CH3, 12 9 CH2, 4 9 CH, 36 9 C at. Anal.
calcd. for C36H52N2O5S2: C, 65.82; H, 7.98; N, 4.26;
Found: C, 66.05; H, 8.15; N, 4.14%.
3-(5-Ethylrhodanine-3-acetyloxyimino)-olean-12-en-28-oic
acid methyl ester (IVg) Yield 81%, mp 183–185ꢁC. IR (m,
cm-1): 1720 (C=O, COOCH3), 1700 (C=O, thiazole), 1620
1
(C=O, COON), 1495 (C=S). H NMR (400 MHz, DMSO-
3-(2,4-Thiazolidinedione-3-acetyloxyimino)-olean-12-en-28-
oic acid methyl ester (IVd) Yield 91%, mp 192–194ꢁC. IR
(m, cm-1): 1725 (C=O, COOCH3), 1705 (C=O, thiazole),
1680 (C=O, thiazole), 1630 (C=O, COON). 1H NMR
(400 MHz, DMSO-d6) d: 0.70 (s, 3H, CH3), 0.89 (s, 6H,
2 9 CH3), 0.99 (s, 3H, CH3), 1.09 (s, 3H, CH3), 1.10 (s, 3H,
CH3), 1.18 (s, 3H, CH3), 2.77–2.88 (m, 1H, C18–H), 3.55 (s,
3H, COOCH3), 4.37 (s, 2H, CH2COON), 4.51 (s, 2H, CH2-
thiazole), 5.19–5.23 (m, 1H, C12–H). 13C NMR (100 MHz,
DMSO-d6) d: 177.8 (C-28), 176.6 (C=O, NHCOCH-thia-
zole), 172.4 (C=O, SCONH-thiazole), 172.0, (C=O,
COON), 166.3 (C-3), 144.2 (C-13), 122.3 (C-12), 52.1
(COOCH3), 46.7 (C-17); DEPT: 8 9 CH3, 12 9 CH2,
4 9 CH, 36 9 C at. Anal. calcd. for C36H52N2O6S: C,
67.47; H, 8.18; N, 4.37; Found: C, 67.57; H, 8.30; N, 4.51%.
d6) d: 0.70 (s, 3H, CH3), 0.89 (s, 6H, 2 9 CH3), 0.98 (s, 3H,
CH3), 1.08 (s, 3H, CH3), 1.10 (s, 3H, CH3), 1.17 (s, 3H, CH3),
2.01–2.10 (m, 2H, CH2CH-thiazole), 2.77–2.87 (m, 1H,
C18–H), 3.55 (s, 3H, COOCH3), 4.79–4.93 (m, 3H,
CH2COO, EtCH-thiazole), 5.18–5.24 (m, 1H, C12–H). 13C
NMR (100 MHz, DMSO-d6) d: 202.6 (C=S), 177.8 (C-28),
176.7 (C=O, thiazole), 176.6 (C=O, COON), 165.5 (C-3),
144.2 (C-13), 122.3 (C-12), 52.1 (C-31), 46.7 (C-17). DEPT:
9 9 CH3, 12 9 CH2, 5 9 CH, 38 9 C at. Anal. calcd. for
C38H56N2O5S2: C, 66.63; H, 8.24; N, 4.09; Found: C, 66.78;
H, 8.32; N, 4.25%.
3-[5-(4-Methoxyphenylmethylidene)-rhodanine-3-acetylox-
yimino)-olean-12-en-28-oic acid methyl ester (IVi)
Yield 95%, mp 102–109ꢁC. IR (m, cm-1): 1725 (C=O,
COOCH3), 1695 (C=O, thiazole), 1620 (C=O, COON),
1500 (C=S), 1270 (Ar-OCH3). 1H NMR (400 MHz,
DMSO-d6) d: 0.72 (s, 3H, CH3), 0.90 (s, 6H, 2 9 CH3),
0.98 (s, 3H, CH3), 1.11 (s, 6H, 2 9 CH3), 1.20 (s, 3H,
CH3), 2.77–2.87 (m, 1H, C18–H), 3.57 (s, 3H, COOCH3),
3.87 (s, 3H, CH3O), 5.05 (s, 2H, NCH2COO), 5.21 (s, 1H,
C12–H), 7.14 (d, J = 8.3 Hz, 2H, Ar), 7.64 (d, J = 8.3 Hz,
2H, Ar), 7.81 (s, 1H, Ar–CH). 13C NMR (100 MHz,
3-(Rhodanine-3-propionyloxyimino)-olean-12-en-28-oic acid
methyl ester (IVe) Yield 82%, mp 152–154ꢁC. IR (m,
cm-1): 1720 (C=O, COOCH3), 1700 (C=O, thiazole), 1635
1
(C=O, COON), 1490 (C=S). H NMR (400 MHz, DMSO-
d6) d: 0.69 (s, 3H, CH3), 0.88 (s, 6H, 2 9 CH3), 0.97 (s, 3H,
CH3), 1.07 (s, 3H, CH3), 1.10 (s, 3H, CH3), 1.16 (s, 3H, CH3),
2.77 (t, J = 7.4, 2H, NCH2CH2), 3.55 (s, 3H, COOCH3),
123

3578
Med Chem Res (2012) 21:3568–3580
DMSO-d6) d: 193.6 (C=S), 177.8 (C-28), 176.9 (C=O,
thiazole), 167.0 (C=O), 165,6 (C-3), 144.1 (C-13), 162.5,
133.9, 126.0, 115.9 (Ar), 122.3 (C-12), 135.2 (Ar–CH=),
118.9 (Ar–CH=C), 52.1 (COOCH3), 46.7 (C-17). DEPT:
9 9 CH3, 11 9 CH2, 9 9 CH, 44 9 C at. Anal. calcd. for
C44H58N2O6S2: C, 68.18; H, 7.54; N, 3.61; Found: C,
68.02; H, 7.72; N, 3.84%.
CH2CH-thiazole), 4.77 (dd, J = 4.3, 7.2 Hz, 1H, CH2CH-
thiazole), 3.57 (s, 3H, COOCH3), 5.17–5.24 (m, 1H, C12–H),
12.1 (s, 1H, NH). 13C NMR (100 MHz, DMSO-d6) d: 177.6
(C-28), 176.0 (C=O, NHCOCH-thiazole), 175.8 (C=O,
COON), 172.3 (C=O, SCONH-thiazole), 169.0 (C-3), 144.0
(C-13), 122.1 (C-12), 51.9 (COOCH3), 46.8 (C-17). DEPT:
7 9 CH3, 10 9 CH2, 5 9 CH, 36 9 C at. Anal. calcd. for
C36H52N2O6S: C, 67.47; H, 8.18; N, 4.37; Found: C, 67.38;
H, 8.09; N, 4.22%.
3-[5-(4-(N,N-Dimethyl)aminophenylmethylidene)-rhodanine-
3-acetyloxyimino)-olean-12-en-28-oic acid methyl ester
(IVj) Yield 89%, mp 128–130ꢁC. IR (m, cm-1): 1715
(C=O, COOCH3), 1700 (C=O, thiazole), 1630 (C=O,
COON), 1505 (C=S), 1280 (Ar). 1H NMR (400 MHz,
DMSO-d6) d: 0.68 (s, 3H, CH3), 0.90 (br.s, 9H, 3 9 CH3),
1.07 (s, 3H, CH3), 1.09 (s, 3H, CH3), 1.16 (s, 3H, CH3),
2.70–2.81 (m, 1H, C18–H), 2.85–2.92 (m, 2H, CH2,
NCH2CH2), 3.07 (s, 6H, N(CH3)2), 3.56 (s, 3H, COOCH3),
4.31–4.37 (m, 2H, CH2 NCH2CH2), 5,13 (br.s, 1H, C12–H),
6.85 (d, J = 8.7 Hz, 2H, Ar), 7.47 (d, J = 8.7 Hz, 2H, Ar),
7.68 (s, 1H, ArCH=). 13C NMR (100 MHz, DMSO-d6) d:
192.9 (C=S), 177.6 (C-28), 175.1 (C=O, thiazole), 168.8
(C=O, COON), 167,2 (C-3), 144.1 (C-13), 152.5, 133.7,
120.4, 112.7 (Ar), 122.2 (C-12), 135.3 (Ar–CH=), 114.7
(Ar–CH=C), 51.9 (COOCH3), 46.7 (C-17). DEPT:
10 9 CH3, 11 9 CH2, 9 9 CH, 46 9 C at. Anal. calcd. for
C46H63N3O5S2: C, 68.88; H, 7.92; N, 5.24; Found: C, 69.00;
H, 8.00; N, 5.35%.
3-[(2,4-Thiazolidinedione-5-ylidene)-carboxylimino]olean-
12-en-28-oic acid methyl ester (IVm) Yield 96%; mp
134–138ꢁC. IR (m, cm-1): 3430 (NH), 1720 (C=O, CO-
OCH3), 1700 (C=O, thiazole), 1680 (C=O, thiazole), 1625
(C=O, COON). 1H NMR (400 MHz, DMSO-d6) d: 0.70 (s,
3H, CH3), 0.88 (s, 6H, 2 9 CH3), 0.99 (s, 3H, CH3), 1.10 (s,
6H, 2 9 CH3), 1.20 (s, 3H, CH3), 2.72–2.95 (m, 1H, C18–H),
3.55 (s, 3H, COOCH3), 5.21 (br.s, 1H, C12–H), 6.97 (s,
1H,=CHCOO). 13C NMR (100 MHz, DMSO-d6) d: 177.6
(C-28), 177.0 (C=O, NHCOCH-thiazole), 169.9 (C=O,
COON), 166.8 (C=O, SCONH-thiazole), 164.15 (C-3),
144.4 (C=CH-thiazole), 144.0 (C-13), 122.2 (C-12), 115.7
(=CH-COON), 51.9 (COOCH3), 46.9 (C-17). DEPT:
8 9 CH3, 10 9 CH2, 5 9 CH, 36 9 C at. Anal. calcd. for
C36H50N2O6S: C, 68.47; H, 7.89; N, 4.38; Found: C, 67.54;
H, 8.05; N, 4.48%.
3-(2,4-Thiazolidinedione-5-acetyloxyimino)-olean-12-en-28-
oic acid morpholide (IVn) Yield 86%, mp 195–197ꢁC. IR
(m, cm-1): 3400 (NH), 1705 (C=O, thiazole), 1695 (C=O,
thiazole), 1630 (C=O, amide), 1620 (C=O, COON), 990 (C–
O, morph.). 1H NMR (400 MHz, DMSO-d6) d: 0.70 (s, 3H,
CH3), 0.88 (s, 6H, 2 9 CH3), 0.97 (s, 3H, CH3), 1.07 (s, 3H,
CH3), 1.09 (s, 3H, CH3), 1.16 (s, 3H, CH3), 2.80–2.90 (m,
1H, C18–H), 2.93–3.03 (m, 1H, CH2CH-thiazole), 3.25–3.31
(m, 1H, CH2CH-thiazole), 4.77 (dd, J = 4.7, 7.2 Hz, 1H,
CH2CH-thiazole), 3.46–3.60 (m, 8H, morph.), 5.09–5.14 (m,
1H, C12–H), 12.10 (br.s, 1H, NH). 13C NMR (100 MHz,
DMSO-d6) d: 176.2 (C-28), 176.0 (C=O, NHCOCH-thia-
zole), 174.7 (C=O, COON), 173.0 (C=O, SCONH-thiazole),
169.3 (C-3), 145.5 (C-13), 121.2 (C-12), 67.0, 47.3 (C-
morph.), 47.0 (C-17). DEPT: 7 9 CH3, 15 9 CH2, 5 9 CH,
39 9 C at. Calcd. for C39H57N3O6S: C, 67.31; H, 8.26; N,
6.04; Found: C, 67.54; H, 8.36; N, 6.21%.
3-(2,4-Thiazolidinedione-5-acetyloxyimino)-olean-12-en-28-
oic acid (IVk) Yield 88%, mp 161–163ꢁC. IR (m, cm-1):
3440 (OH, COOH and NH), 1700 (C=O, thiazole), 1685
(C=O, thiazole), 1670 (C=O, COOH), 1620 (C=O, COON).
1H NMR (400 MHz, DMSO-d6) d: 0.76 (s, 3H, CH3), 0.88 (s,
6H, 2 9 CH3), 0.98 (s, 3H, CH3), 1.08 (s, 3H, CH3), 1.10 (s,
3H, CH3), 1.17 (s, 3H, CH3), 2.74–2.86 (m, 1H, C18–H),
2.34–2.44 (m, 1H, CH2CH-thiazole), 3.24–3.31 (m, 1H,
CH2CH-thiazole), 4.74–4.81 (m, 1H, CH2CH-thiazole),
5.15–5.21 (m, 1H, C12–H), 12.10 (br.s, 1H, NH). 13C NMR
(100 MHz, DMSO-d6) d: 179.0 (C-28), 176.0 (C=O,
NHCOCH-thiazole), 172.7 (C=O, COON), 169.1 (C=O,
SCONH-thiazole), 163.8 (C-3), 144.4 (C-13), 121.8 (C-12),
47.0 (C-17). DEPT: 7 9 CH3, 11 9 CH2, 5 9 CH, 35 9 C
at. Anal. calcd. for C35H50N2O6S: C, 67.06; H, 8.04; N, 4.47;
Found: C, 66.85; H, 8.23; N, 4.60%.
3-(2,4-Thiazolidinedione-5-acetyloxyimino)-olean-12-en-28-
oic acid methyl ester (IVl) Yield 88%, mp 172–174ꢁC. IR
(m, cm-1): 3420 (NH), 1720 (C=O, COOCH3), 1695 (C=O,
3-[(2,4-thiazolidinedione-5-ylidene)-carboxylimino]olean-
12-en-28-oic acid morpholide (IVo) Yield 85%, mp
164–166ꢁC. IR (m, cm-1): 3449 (NH), 1710 (C=O, thia-
zole), 1695 (C=O, thiazole), 1630, 1620 (2 9 C=O, COON
and amide), 990 (C–O, morph.). 1H NMR (400 MHz,
DMSO-d6) d: 0.70 (s, 3H, CH3), 0.87 (s, 6H, 2 9 CH3),
0.98 (s, 3H, CH3), 1.10 (s, 6H, 2 9 CH3), 1.19 (s, 3H,
CH3), 2.43 (m, 1H, C2–H), 2.89–3.00 (m, 1H, C18–H),
1
thiazole), 1680 (C=O, thiazole), 1620 (C=O, COON). H
NMR (400 MHz, DMSO-d6) d: 0.70 (s, 3H, CH3), 0.88 (s,
6H, 2 9 CH3), 0.98 (s, 3H, CH3), 1.07 (s, 3H, CH3), 1.10 (s,
3H, CH3), 1.16 (s, 3H, CH3), 2.75–2.87 (m, 1H, C18–H),
3.24–3.30 (m, 1H, CH2CH-thiazole), 3.54–3.62 (m, 1H,
123

Med Chem Res (2012) 21:3568–3580
3579
Boyd MR, Paull KD (1995) Some practical considerations and
applications of the national cancer institute in vitro anticancer
drug discovery screen. Drug Dev Res 34:91–109
Brier S, Lemaire D, Debonis S, Forest E, Kozielski F (2004)
Identification of the protein binding region of S-trityl-L-cysteine,
a new potent inhibitor of the mitotic kinesin Eg5. Biochem
43:13072–13082
Chen J, Liu J, Zhang L, Wu G, Hua W, Wu X, Suna H (2006)
Pentacyclic triterpenes. Part 3: synthesis and biological evalu-
ation of oleanolic acid derivatives as novel inhibitors of
glycogen phosphorylase. Bioorg Med Chem Lett 16:2915–2919
Cichewicz RH, Kouzi SA (2004) Chemistry, biological activity, and
chemotherapeutic potential of betulinic acid for the prevention
and treatment of cancer and HIV infection. Med Res Rev
24:90–114
Couch RD, Browning RG, Honda T, Gribble GW, Wright DL, Sporn
MB, Anderson AC (2005) Studies on the reactivity of CDDO, a
promising new chemopreventive and chemotherapeutic agent:
implications for a molecular mechanism of action. Bioorg Med
Chem Lett 15:2215–2219
Cutshall NS, O’Day C, Prezhdo M (2005) Rhodanine derivatives as
inhibitors of JSP-1. Bioorg Med Chem Lett 15:3374–3379
Deghengni R, Daneault G (1960) Orotic acid and its analogues: part
II. On the alkaline rearrangement of 5-carboxymethylidenehy-
dantoin. Can J Chem 38:1255–1260
Degterev A, Lugovskoy A, Cardone M, Mulley B, Wagner G,
Mitchison T, Yuan J (2001) Identification of small-molecule
inhibitors of interaction between the BH3 domain and Bcl-xl.
Nat Cell Biol 3:173–182
Dinkova-Kostova AT, Liby KT, Stephenson KK, Holtzclaw WD, Gao
X, Suh N, Williams C, Risingsong R, Honda T, Gribble GW,
Sporn MB, Talalay P (2005) Extremely potent triterpenoid
inducers of the phase 2 response: Correlations of protection
against oxidant and inflammatory stress. PNAS 102:4584–4589
Finlay HJ, Honda T, Gribble GW (2002) Synthesis of novel [3,
2-b]indole fused oleanolic acids as potential inhibitors of cell
proliferation. ARKIVOC XII:38–46
Han SK, Ko YI, Park SJ, Jin IJ, Kim YM (1997) Oleanolic acid and
ursolic acid stabilize liposomal membranes. Lipids 32:769–773
Havrylyuk D, Zimenkovsky B, Vasylenko O, Zaprutko L, Gzella A,
Lesyk R (2009) Synthesis of novel thiazolone-based compounds
containing pyrazoline moiety and evaluation of their anticancer
activity. Eur J Med Chem 44:1396–1404
3.46–3.60 (m, 8H, morph.), 5.08–5.14 (m, 1H, C12–H),
7.03 (s, 1H, =CHCOO). 13C NMR (100 MHz, DMSO-d6)
d: 177.1 (C-28), 176.8 (C=O, NHCOCH-thiazole), 175.2
(C=O, COON), 174.1 (C=O, SCONH-thiazole), 169.6 (C-
3), 145.7 (CH=C-thiazole), 144.9 (C-13), 121.2 (C-12),
116.0 (=CH–COON), 67.0, 46.6 (C-morph.), 47.1 (C-17).
DEPT: 7 9 CH3, 14 9 CH2, 5 9 CH, 39 9 C at. Anal.
calcd. for C39H55N3O6S: C, 67.31; H, 8.26; N, 6.04; Found:
C, 67.54; H, 8.36; N, 6.21%.
12a-Bromo-3-(2,4-thiazolidinedione-5-acetyloxyimino)-olean-
28b ? 13b olide (IVp) Yield 83%, mp 152–154ꢁC. IR (m,
cm-1): 1760 (C=O, lacton) 1710 (C=O, thiazole), 1690
(C=O, thiazole), 1635 (C=O, COON). 1H NMR (400 MHz,
DMSO-d6) d: 0.87 (s, 3H, CH3), 0.92 (s, 3H, CH3), 0.97 (s,
3H, CH3), 1.09 (s, 3H, CH3), 1.16 (s, 3H, CH3), 1.18 (s, 3H,
CH3), 1.40 (s, 3H, CH3), 2.72–2.82 (m, 1H, C18–H),
3.26–3.30, 3.57–3.59, 4.54–4.58 (3 9 m, 3H, CH2CH-thia-
zole), 4.76–4.82 (m, 1H, C12–H), 12.10 (br.s, 1H, NH). 13
C
NMR (100 MHz, DMSO-d6) d: 178.3 (C-28), 176.1 (C=O,
NHCOCH-thiazole), 172.9 (C=O, COON), 172.2 (C=O,
SCONH-thiazole), 169.2 (C-3), 91.5 (C-13), 57.2 (C-12),
45.5 (C-17). DEPT: 7 9 CH3, 11 9 CH2, 5 9 CH, 35 9 C
at. Anal. calcd. for C35H49BrN2O6S: C, 59.57; H, 7.00; N,
3.97; Found: C, 59.74; H, 7.18; N, 4.10%.
12a-Bromo-3-[(2,4-thiazolidinedione-5-ylidene)-carboxylimi-
no]olean-28b ? 3b olide (IVq)
Yield 87%, mp 183–
185ꢁC. IR (m, cm-1): 1755 (C=O, lacton) 1700 (C=O, thia-
zole), 1690 (C=O, thiazole), 1635 (C=O, COON). 1H NMR
(400 MHz, DMSO-d6) d: 0.88 (s, 3H, CH3), 0.89 (s, 3H,
CH3), 0.95 (s, 3H, CH3), 0.96 (s, 3H, CH3), 1.03 (s, 3H, CH3),
1.17 (s, 3H, CH3), 1.41 (s, 3H, CH3), 2.37–2.45 (m, 1H, C18–
H), 4.54–4.60 (br.s, 1H, C12–H), 7.02 (s, 1H, =CH-thiazole)
12.33 (s, 1H, NH). 13C NMR (100 MHz, DMSO-d6) d: 178.3
(C-28), 174.8 (C=O, NHCOCH-thiazole), 173.6 (C=O,
COON), 171.5 (C=O, SCONH-thiazole), 170.2 (C-3), 155.7
(CH=C-thiazole), 119.6 (=CH–COON), 91.6 (C-13), 57.4
(C-12), 45.4 (C-17). DEPT: 7 9 CH3, 10 9 CH2, 5 9 CH,
35 9 C at. Anal. calcd. for C35H47BrN2O6S: C, 59.74; H,
6.73; N, 3.98; Found: C, 58.00; H, 6.98; N, 4.12%.
Hollingshead MG, Alley MC, Camalier RF, Abbott BJ, Mayo JG,
Malspeis L, Grever MR (1995) In vivo cultivation of tumor cells
in hollow fibers. Life Sci 57:131–141
Honda T, Gribble GW, Suh N, Finlay HJ, Rounds BV, Bore L,
Favaloro FG Jr, Wang Y, Sporn MB (2000a) Novel synthetic
oleanane and ursane triterpenoids with various enone function-
alities in ring A as inhibitors of nitric oxide production in mouse
macrophages. J Med Chem 43:1866–1877
Honda T, Rounds BV, Bore L, Finlay HJ, Favaloro FG Jr, Suh N,
Wang Y, Sporn MB, Gribble GW (2000b) Synthetic oleanane
and ursane triterpenoids with modified rings A and C: a series of
highly active inhibitors of nitric oxide production in mouse
macrophages. J Med Chem 43:4233–4246
Acknowledgment We are grateful to Dr. V.L. Narayanan from
Drug Synthesis and Chemistry Branch, National Cancer Institute,
Bethesda, MD, USA, for evaluation of anticancer activity.
Kaminskyy DV, Lesyk RB (2010) Structure-anticancer activity
relationships among 4-azolidinone-3-carboxylic acids deriva-
tives. Biopolym Cell 26:136–145
References
Kaminskyy D, Zimenkovsky B, Lesyk R (2009) Synthesis and in vitro
anticancer activity of 2,4-azolidinedione-acetic acids derivatives.
Eur J Med Chem 44:3627–3636
Konoki MHK, Tachibana K (1996) Cholesterol-independent mem-
brane disruption caused by triterpenoid saponins. Biochim
Biophys Acta 1299:252–258
Bodor N (1984) Novel approaches to the design of safer drugs: soft
drugs and chemical deliver systems. In: Testa B (ed) Advances
in drug research. Academic Press, Orlando, pp 255–331
Boyd MR (1997) In: Teicher BA (ed) Cancer drug discovery and
development. Humana Press, Totowa, pp 23–43
123

3580
Med Chem Res (2012) 21:3568–3580
Lee J, Kim J, Koh JS, Chung HH, Kim KH (2006) Hydantoin
derivatives as non-peptidic inhibitors of Ras farnesyl transferase.
Bioorg Med Chem Lett 16:1954–1956
Lesyk RB, Zimenkovsky BS (2004) 4-Thiazolidones: centenarian
history, current status and perspectives for modern organic and
medicinal chemistry. Curr Org Chem 8:1547–1578
Lesyk R, Zimenkovsky B, Troc’ko N, Kazmirchuk G (2002)
Synthesis of 5-arylidene-2,4-thiazolidin-3-yl alkanoic acids.
Annal UMCS Sec DDD 15:39–45
Plowman J, Dykes DJ, Hollingshead M, Simpson-Herren L, Alley
MC (1997) Human tumor xenograft models in NCI drug
development. In: Teicher B (ed) Anticancer drug development
guide: preclinical screening, clinical trials, and approval.
Humana Press, Totowa, pp 101–125
Popov-Pergal K, Rancic M, Pergal M, Bogdanovic G, Kojic V,
Djokovic D (2006) Synthesis and biological activity evaluation
of new functionally substituted 5-arylidene-2,4-dioxotetrahydro-
1,3-thiazoles. J Serb Chem Soc 71:61–866
Lesyk R, Zimenkovsky B, Kaminskyy D, Holota S, Atamanyuk D,
Havrylyuk D, Nektegaev I, Kazmirchuk G, Subtel’na I, Roman
O, Kryshchyshyn A, Khyluk D (2006) Anticancer potential of
4-azolidones and related heterocycles. Annal UMCS Sec DDD
19:107–110
Shirane N, Hashimoto Y, Ueda K, Takenaka H, Katoh K (1996) Ring-
A cleavage of 3-oxo-olean-12-en-28-oic acid by the fungus
chaetomium longirostre. Phytochem 43:99–104
Shoemaker RH (2006) The NCI 60 human tumour cell line anticancer
drug screen. Nat Rev Cancer 6:813–823
Lewis KG, Tucker DJ (1983) The separation of substituted olean-12-
en-28-oic acid from the corresponding Urs-12-en-28-oic acid
isomers. Aust J Chem 36:2297–2305
Liby KT, Yore MM, Sporn MB (2007) Triterpenoids and rexinoids as
multifunctional agents for the prevention and treatment of
cancer. Nat Rev Cancer 7:357–369
Liu J (2005) Oleanolic acid and ursolic acid: research perspectives.
J Ethnopharmacol 100:92–94
Ma C, Nakamura N, Hattori M (2000) Chemical modification of
oleanene type triterpenes and their inhibitor activity against
HIV-1 protease dimerization. Chem Pharm Bull (Tokoyo)
48:1681–1688
Simonsen J, Rossk WCI (1957) The terpenes. Volume 5: the
triterpenes and their derivatives. University Press, Cambridge
´
´
Subtel’na I, Atamanyuk D, Szymanska E, Kiec-Kononowicz K,
Zimenkovsky B, Vasylenko O, Gzella A, Lesyk R (2010)
Synthesis of 5-arylidene-2-amino-4-azolones and evaluation of
their anticancer activity. Bioorg Med Chem 18:5090–5102
Teng X, Degterev A, Jagtap P, Xing X, Choi S, Denu R, Yuan J, Cuny
GD (2005) Structure-activity relationship study of novel nec-
roptosis inhibitors. Bioorg Med Chem Lett 15:5039–5044
Yakubych VY, Fedirko YaM (1983) Synthesis and properties of
rhodanines synthesized base on aspartic acid. Farmacevtychnyj
Zhurn (Kyiv) 5:58–60 In Ukrainian
Ma C, Nakamura N, Hattori M, Kawahata T, Otake T (2002)
Inhibitory Effects of triterpene–azidothymidine conjugates on
proliferation of human immunodeficiency virus type 1 and its
protease. Chem Pharm Bull (Tokoyo) 50:877–880
Mallarno JP, Pilling GM, Wetzel JR, Kowalczyk PJ, Bell MR,
Kullnig RK, Batzold FH, Juniewicz PE, Winneker RC, Luss HR
(1992) Anti-androgenic steroidal sulfonyl heterocycles. Utility
of electrostatic complementarity in defining bioisosteric sulfonyl
heterocycles. J Med Chem 35:1663–1670
Yasue M, Sakakibara J, Kaiya T (1974) Syntheses of nitrogen-
containing triterpenes. III Derivatives of betulinic acid and
oleanolic acid. J Pharm Soc Jpn 94:1468–1474
Zaharevitz DW, Holbeck SL, Bowerman C, Svetlik PA (2002)
COMPARE: a web accessible tool for investigating mechanisms
of cell growth inhibition. J Mol Graphics Model 20:297–303
Zaprutko L, Partyka D, Bednarczyk-Cwynar B (2004) Triterpenoids.
Part 21. Olenolic acid azaderivatives as perculatenous transport
promoters. Bioorg Med Chem Lett 14:4723–4726
Monks A, Scudiero D, Skehan P, Shoemaker R, Paull K, Vistica D,
Hose C, Langley J, Cronise P, Vaigro-Wolff A (1991) Feasibility
of a high-flux anticancer drug screen using a diverse panel of
cultured human tumor cell lines. J Nat Cancer Inst 83:757–766
Nair KG, Moayeri H, Mittelman A (1980) A phase II study of
fluorodopan in the treatment of advanced colorectal cancer.
Cancer Treat Rep 64:697–699
Zimenkovsky B, Kutsyk R, Lesyk R, Matiychuk V, Obushak N,
Klyufinska T (2006) Synthesis and antimicrobial activity of 2,4-
dioxothiazolidine-5-acetic acid amides. Pharm Chem J 40:
303–306
123