Antiproliferative activity and QSAR studies of a series of new 4-aminomethylidene derivatives of some pyrazol-5-ones

Article abstract of DOI:10.1016/j.bmcl.2011.06.025

Twenty five 4-aminomethylidene derivatives obtained from 3-phenyl-2-pyrazolin-5-one and 1,3-diphenyl-2-pyrazolin-5-one were synthesized and tested for their antiproliferative activity against human breast cancer MDA-MB-361 and MDA-MB-453 cell lines. The compounds derived from 1,3-diphenyl-2-pyrazolin-5-one exhibited the most remarkable activity in the treatment of both cell lines. In vitro antiproliferative activities were accompanied by an important apoptotic fraction of both cell lines; also, compounds inhibited key endothelial cell functions implicated in invasion and angiogenesis. QSAR methods were performed in order to analyze the influence of structural features of the compounds investigated on the antiproliferative potential on MDA-MB-361 and MDA-MB-453 cancer cells. One-parameter heuristic analysis was performed and different whole molecule and fragmental descriptors were considered for rationalization of mechanism of interaction of these compounds with active place of hypothetical target included in tumorigenesis.

Full text of DOI:10.1016/j.bmcl.2011.06.025

Bioorganic & Medicinal Chemistry Letters 21 (2011) 4416–4421
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Antiproliferative activity and QSAR studies of a series of new
4-aminomethylidene derivatives of some pyrazol-5-ones
a
b
c
c
c
-
´
´
´
´
´
Violeta Markovic , Slavica Eric , Tatjana Stanojkovic , Nevenka Gligorijevic , Sandra Arandelovic ,
d
e
f
f
a,
⇑
´
ˇ
´
´
´
´
Nina Todorovic , Snezana Trifunovic , Nedeljko Manojlovic , Ratomir Jelic , Milan D. Joksovic
a Faculty of Sciences, Department of Chemistry, University of Kragujevac, R. Domanovi´ca 12, 34000 Kragujevac, Serbia
b Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11000 Belgrade, Serbia
c Institute of Oncology and Radiology of Serbia, Pasterova 14, 11000 Belgrade, Serbia
d Institute for Chemistry, Technology and Metallurgy, Njegoševa 12, 11000 Belgrade, Serbia
e Faculty of Chemistry, University of Belgrade, Studentski trg 16, PO Box 158, 11000 Belgrade, Serbia
f Medical Faculty, University of Kragujevac, S. Markovic´a 69, 34000 Kragujevac, Serbia
a r t i c l e i n f o
a b s t r a c t
Article history:
Twenty five 4-aminomethylidene derivatives obtained from 3-phenyl-2-pyrazolin-5-one and 1,3-diphe-
nyl-2-pyrazolin-5-one were synthesized and tested for their antiproliferative activity against human
breast cancer MDA-MB-361 and MDA-MB-453 cell lines. The compounds derived from 1,3-diphenyl-2-
pyrazolin-5-one exhibited the most remarkable activity in the treatment of both cell lines. In vitro
antiproliferative activities were accompanied by an important apoptotic fraction of both cell lines; also,
compounds inhibited key endothelial cell functions implicated in invasion and angiogenesis. QSAR
methods were performed in order to analyze the influence of structural features of the compounds inves-
tigated on the antiproliferative potential on MDA-MB-361 and MDA-MB-453 cancer cells. One-parameter
heuristic analysis was performed and different whole molecule and fragmental descriptors were consid-
ered for rationalization of mechanism of interaction of these compounds with active place of hypothetical
target included in tumorigenesis.
Received 8 April 2011
Revised 6 June 2011
Accepted 8 June 2011
Available online 16 June 2011
Keywords:
Pyrazolones
Antiproliferative activity
Breast cancer
Angiogenesis
QSAR studies
Ó 2011 Elsevier Ltd. All rights reserved.
Chemistry and applications of pyrazolone derivatives represent
a very active research area due to a wide range of biological activ-
ities and outstanding pharmacological properties. Among them,
antipyrine (2,3-dimethyl-1-phenylpyrazol-5-one) and its analogs
aminopyrine, dipyrone and propyphenazone are known for a long
time as antipyretic, analgesic and anti-inflammatory substances.1
Recently, a new pyrazol-5-one compound, edaravone (3-methyl-
1-phenyl-2-pyrazoline-5-one, RadicutÒ, Mitsubishi Tanabe Pharma
Corporation) has been developed as a promising drug for the treat-
ment of brain ischemia,2 and its pharmacological actions were
attributed to its antioxidant activity as a potent hydroxyl radical
scavenger.3
4,4-dichloro-1-(2,4-dichlorophenyl)-3-methylpyrazol-5-one
is
found to be a specific potent catalytic blocker of human telome-
rase, and, therefore, a valuable substance for medical treatment
of cancer and related diseases.6 It was discovered that thiadiazole
substituted pyrazol-5-ones were potent KDR kinase inhibitors in
regulating angiogenesis which is important for the proliferation
of tumor cells.7
It is known that toxic side effects of cytotoxic drugs are
manifested through production of an irreversible damage to nor-
mal cell lines affecting cellular metabolic pathways.8–10 From this
point of view, it is important to minimize the toxic or other un-
wanted actions and retain favorable pharmacological potential of
the new antitumor compounds. For this purpose, we assumed that
incorporation of nontoxic biomolecule into the heterocyclic scaf-
fold could have attractive biological results, comparable with those
obtained by introduction of the confirmed antitumor pharmaco-
phore. In our intention to evaluate the efficacy of biomolecule
moiety, two classes of 4-aminomethylidene derivatives of two
pyrazol-5-ones were synthesized. The first class contains amino
acid moiety, while the second one is characterized by presence of
the known antitumor 3-aminopyrazole pharmacophore.11,12 The
substituents were selected to provide a good coverage of polar, ste-
ric, electron-donating or withdrawing properties for QSAR analysis.
The importance of pyrazolone derivatives has also been in-
creased by their application as antitumor agents. For example,
certain diphenyl pyrazolone derivatives were studied for their
regulatory activity on TNF-
a production in human promyelocytic
leukemia (HL-60) cells.4 Some pyrazolone compounds derived
from edaravone inhibited the protease-resistant prion protein
accumulation, a component which is considered to be responsible
for the pathogenesis.5 Furthermore,
a
new compound,
⇑
Corresponding author. Tel.: +381 34 336223; fax: +381 34 335040.
E-mail address: mjoksovic@kg.ac.rs (M.D. Joksovic´).
0960-894X/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2011.06.025

´
4417
V. Markovic et al. / Bioorg. Med. Chem. Lett. 21 (2011) 4416–4421
Indeed, we observed no significant difference in inhibition of
which can be assigned to
m
(N–H) and
m(C@O) and respectively,
human breast cancer MDA-MB-361 cells between two pyrazol-5-
one derivatives with 5-methyl-3-aminopyrazole and phenylala-
nine moiety including both enantiomers of amino acid.
indicating the tautomer B with exocyclic double bond as a predom-
inant form. Like amines, in the IR spectra of the amino acid deriv-
atives of pyrazol-5-ones, the presence of the strongest absorption
All pyrazol-5-one derivatives were synthesized according to
Scheme 1. Pyrazolone compounds (3-phenyl-2-pyrazolin-5-one
and 1,3-diphenyl-2-pyrazolin-5-one), obtained by the condensa-
tion reaction of b-keto esters with hydrazine or phenylhydrazine
were formylated under Vilsmeier conditions with POCl3 and N,N-
dimethylformamide.13 The formed aldehyde was then reacted with
selected 3-aminopyrazoles and amino acids affording the desired
4-aminomethylidene derivatives of pyrazol-5-ones 1a–1y in mod-
erate to good yields.14 In the reaction of 4-formylpyrazolone pre-
cursor with 3-aminopyrazoles the presence of catalitical amount
of p-toluenesulfonic acid is necessary to prevent enolization of car-
bonyl group and a shift of tautomeric equilibria towards starting
tautomeric form with exocyclic double bond.
band positioned at 1650–1670 cmÀ1 may be attributed to
m(C@O)
vibrations of the pyrazolone ring confirming the tautomeric form
B in the solid state. In addition, amino acid derivatives show also
a wide band for the O–H stretch in the region of 3220–3285 cm
À1
while the carbonyl stretch appears as a medium intense band
between 1710 and 1736 cmÀ1. These observations are in accor-
dance with IR spectra of some aminomethylidene derivatives of
pyrazol-5-one15 and are consistent with the X-ray analysis of sim-
ilar compounds.16
On the basis of information obtained from 1H NMR spectra of
amine derivatives in DMSO-d6 solution, we can conclude that only
compound 1m exists in tautomeric form B due to appearance of a
doublet for exocyclic CH and NH protons as a result of the coupling
between them with the relatively large geminal coupling constant
of 13.0 Hz. All other amine derivatives of both pyrazol-5-ones and
amino acid derivatives of 3-phenyl-2-pyrazolin-5-one were pres-
ent in the form of OH (C) or NH (D) tautomer. The NH (D) form re-
quires a signal in the higher field15 that was not observed in our
spectra, although an averaged signal set can not be excluded as a
consequence of a rapid chemical exchange on the NMR timescale
The aminomethylidene derivatives of 4-formylpyrazol-5-ones
1a–1y can exist in four tautomeric forms as depicted in Scheme
1. in dependence on the position and substituent kind of pyrazo-
lone nucleus, structural variations of 3-aminopyrazole moiety
and solvent polarity.
The IR spectra of amine derivatives exhibit two characteristic
bands in the range of 3415–3436 cmÀ1 and 1656–1680 cmÀ1
Scheme 1. Reagents and conditions: (a) PhNHNH2 or NH2NH2, EtOH, reflux, 3 h; (b) DMF, POCl3, heat, 80 °C, 1.5 h; (c) for amines: p-TSA, EtOH, reflux, 2 h; for amino acids:
EtOH, reflux 4 h.

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V. Markovic et al. / Bioorg. Med. Chem. Lett. 21 (2011) 4416–4421
4418
between OH (C) and NH (D) tautomer.17 It is important to point out
here that this signal was strongly deshielded in most of the cases
because of intramolecular hydrogen bonding with other N/O
atoms.
However, amino acid derivatives of 1,3-diphenyl-2-pyrazolin-5-
one exist only in tautomeric form B. All these compounds display
doublets for exocyclic CH protons and vicinal NH protons. More-
over, for methine proton of amino acid moiety an additional dou-
blet of doublets (dd) splitting into ddd occurred because of
coupling with the vicinal NH proton, instead of expected dd for
any other tautomeric form.
Antiproliferative activity of all synthesized compounds 1a–1y
was evaluated against MDA-MB-361 (estrogen-dependent) and
MDA-MB-453 (estrogen-nondependent) human breast cancer cells
with cisplatin (cis-DDP) as referent cytostatic. It is noteworthy to
emphasize that MDA-MB-361 cell line is resistant towards widely
used cytostatic drugs such as Paclitaxel, Doxorubicin and 5-fluoro-
uracil.18 Table 1 represents the results of cytotoxic activity.
The compounds derived from 1,3-diphenyl-2-pyrazolin-5-one
(1m–1y) showed the most potent antiproliferative activity against
both cell lines. Compounds 1n, 1o, 1q, 1r, 1s, 1t and 1u exhibited
stronger cytotoxicity in inhibition of MDA-MB-361 type cell line
in comparison with cisplatin, with 1o as the most active one. Estro-
gen-nondependent cancer cell line MDA-MB-453 was less sensitive
to the application of this group of compounds, but generally keep-
ing the same relative activity. In this case, the most active one ap-
peared to be 1q, compound containing 5-phenylpyrazole moiety,
with IC50 value being approximately 2-fold higher than cisplatin.
On the other hand, compounds derived from 3-phenyl-2-pyrazo-
lin-5-one (1a–1l) showed significantly lower activity regarding
both cell lines. The cytotoxicity increases only upon introduction
of phenyl group into pyrazole moiety (1e). Certainly, we did not ex-
clude the influence of tautomerism on antiproliferative activity,
but results reported herein showed that the introduction of the
second phenyl group can overcome the effect of tautomerism on
cytotoxicity, suggesting planar aromatic requirements for better
cytotoxic activity. In diphenylpyrazolone derivatives the presence
of the additional phenyl group could also lead to the emphasized
contribution of the sulphur containing amino acid side chain, re-
lated to the beter possibilities for interactions with various active
centers. This is indicated by much higher IC50 values for methio-
nine and S-methyl cysteine derivatives 1g and 1h than the corre-
sponding 1t and 1u.
Since these compounds did not show significant antioxidant
activity, it was supposed that their mechanism of action is not con-
nected with free radical scavenging activity. Therefore, we chose to
examine the mechanism of action of 1a–1y by cytofluorimetric
analysis, using propidium iodide to label DNA. After treatment of
MDA-MB-453 and MDA-MB-361 cells with 1a–1y (IC50), the cells
were harvested and analyzed with a FACScalibur flow cytometer.
A representative cell cycle analysis of cancer cell lines treated with
some compounds for 24 h is given in Fig. 1. We observed that
in vitro antiproliferative activity was accompanied by an important
sub-G1 fraction of MDA-MB-453 and MDA-MB-361 cell lines after
treatment with pyrazolone compounds. An increase in cells con-
taining sub-G1 amounts of DNA was observed, indicating that
the tested compounds induced apoptosis. Specially, the 1m–1y
showed the strongest increase in the percentage of the sub-G1
population in the both cell line, and led to a G0/G1 cell cycle block.
This was consistent with the compounds inducing apoptosis in a
cell cycle-dependent manner.
In order to examine the effect of our investigated pyrazolones
on angiogenesis in vitro, the tube formation assay was performed.
Angiogenesis involves endothelial cells proliferation, migration
and capillary tube formation. When seeded onto matrigel in the
presence of appropriate media MS1 cells start to reorganize, form-
ing polygon structures. In our experiment MS1 endothelial cells
were treated with sub-toxic concentrations of investigated com-
pounds in order to distinguish among growth inhibitory effect of
tested pyrazolones and their potential to inhibit tube-like struc-
tures formation. The strongest anti-angiogenic effect was observed
in the group of compounds exhibiting relatively low antiprolifera-
Table 1
tive activity (up to 100 lM), which where applied at 30 lM con-
centration (compounds 1c, 1g, 1h, 1i, 1k, 1l). Some results are
presented in Fig. 2. Among the compounds applied at concentra-
tion of 3 lM, compounds 1r, 1p, 1o, 1n, 1q show potential to inhi-
bit characteristics of angiogenic behavior of endothelial cells,
although this may account to their antiproliferative potential.
Other tested pyrazolones did not exhibit any significant anti-
angiogenic effect.
IC50
(lM) for the 72 h of action of investigated compounds and cisplatin on the MDA-
MB-361 and MDA-MB-453 cells determined by MTT test
Compounds
MDA-MB-361
MDA-MB-453
⁄
IC50
(
lM)
1a
1b
1c
1d
1e
120.57 6.44
63.71 2.69
96.05 1.17
95.34 3.16
42.66 2.71
67.05 5.62
105.11 5.33
97.36 1.33
104.61 6.77
61.06 1.39
113.33 0.71
93.63 2.02
24.65 0.36
13.36 1.31
9.98 1.35
51.01 2.93
12.17 0.07
11.53 0.66
11.88 0.28
12.47 1.35
14.22 1.78
52.75 3.97
24.79 2.88
87.24 1.66
33.86 0.87
14.74 0.36
74.61 4.41
20.86 2.01
93.00 2.83
74.86 0.98
11.53 0.96
94.78 3.40
42.15 2.35
105.23 0.31
23.69 0.09
29.77 2.75
73.89 4.88
41.66 5.11
19.35 2.90
12.36 2.23
10.24 0.41
34.66 1.51
8.75 0.08
10.43 1.74
9.66 2.14
9.43 0.74
9.46 1.05
49.01 3.31
10.92 0.43
71.11 0.58
9.75 1.01
3.75 0.12
In this work, we performed QSAR analysis of newly synthesized
derivatives of pirazol-5-one which differ at position 1 and 4. Whole
set of 25 compounds was divided in two subsets: subset 1, com-
posed of compounds without substituent at position 1 (1a–1l),
and subset 2, containing compounds with phenyl ring at position
1 of pyrazol-5-one (1m–1y). Heuristic analysis for calculation
and selection of the most significant descriptors was performed
for whole set and two subsets. Number of whole molecule and
fragmental descriptors were calculated and analyzed, where frag-
ments represented variable substituents connected to amino group
at position 4 of pyrazol-5-one.
The results of one-parameter analysis for activity of compounds
on MDA-MB-453 are presented in Table 2. The five most significant
descriptors calculated for all 25 molecules belong to the group of
topological, geometrical and quantum-chemical descriptors. Geo-
metrical descriptors such as ZX shadow (SZX, r2 = 0.5405) and
Molecular Surface Area (MSA, r2 = 0.5038) were found to be impor-
tant factors for interaction with target, which indicates that size
and shape of the whole molecule play crucial role in binding to
hypothetical precise active site of enzyme. Polarizability of the
1f
1g
1h
1i
1j
1k
1l
1m
1n
1o
1p
1q
1r
1s
1t
1u
1v
1w
1x
1y
Cis-DDP
*
Concentrations of examined compounds that induced a 50% decrease in MDA-
MB-361 and MDA-MB-453 cell survival (expressed IC50 M)).
(l
molecules, described by ALFA Polarizability descriptor
(a,

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V. Markovic et al. / Bioorg. Med. Chem. Lett. 21 (2011) 4416–4421
Fig. 1. Cell cycle distribution after 24 h of continuous action of (IC50) compounds 1p, 1o, and 1n in MDA-MB-361 cell lines. After a 24 h exposure to compounds concentration,
cells were harvested and subjected to PI flow cytometry.
r2 = 0.5244), as well as polar surface area described by Surface
Weighted Partial Positive Charged Surface Area (qWPSA-1,
r2 = 0.5081), indicate the importance of polarity of the molecules
for antiproliferative activity. The most important descriptor which
is, as results show, Complementary Information Content (1CIC,
r2 = 0.5571), derived from number of atoms and atomic layers in
the coordination sphere around given atoms, could be connected
with the size of molecule and connectivity of atoms which is
important for interactions with potential target. Fragmental
descriptors related to substituents of amino group at position 4
of pyrazol-5-one did not appear to be very significant in whole
set analysis.
As it was mentioned above, subsets 1 and 2 differ in phenyl sub-
stituent at position 1 of pyrazol-5-one. The most significant
descriptors calculated for subset 1 differ from the most significant
descriptors calculated for whole set, but for both sets is important
geometrical descriptor ZX Shadow (SZX). Regardless of existence of
substituent at position 1 and type of substituent at position 4,
geometry of the molecules is important for fitting to the main
cavity of active site. For subset 1, polarity again plays significant
role, as well as quantum-chemical properties described by descrip-
tor e
LUMO+1, (r2 = 0.3456), which describes the energy of the second
lowest unoccupied molecular orbit. The most significant descriptor
obtained by analysis of subset 2 include fragmental descriptors
(marked with prefix f- in the name of descriptor), therefore the
structural features of variable fragments connected to amino group
at position 4 play more important role in case of subset 2, probably
because planar phenyl group at position 1 influence a more favor-
able conformation of fragment during interactions with active site.
It indicates an existence of hydrophobic pocket at active place
interacting with phenyl ring, so that the substituent at position 4
is properly oriented and placed for interaction with other residues
of active site. Even more, we considered possible existence of more
than one active site for interactions with enzyme. The most signif-
icant descriptor is f-Fractional H-donor Charged Surface Area
(qf-FHDCA, r2 = 0.8129) which is indicative for hydrogen bonding
interactions between fragment and residues. Since correlation
coefficient is so high, it gives us some guidance in further synthesis

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V. Markovic et al. / Bioorg. Med. Chem. Lett. 21 (2011) 4416–4421
4420
Fig. 2. Angiogenesis in vitro: tube formation on collagen. Representative micrographs of tube formation in MS1 cells treated for 24 h with tested compounds (1c, 1g, 1h) at
concentration 30 lM, versus control.
Table 2
The most significant descriptors for antiproliferative activity on MDA-MB-453 cells selected by heuristic method
Whole set (n = 25) 1a–1l (n = 12)
1m-1y (n = 13)
1.
2.
3.
4.
r
r
r
r
2 = 0.5571 F = 28.93
2 = 0.5405 F = 27.05
2 = 0.5244 F = 25.36
2 = 0.5081 F = 23.76
1CIC
SZX
r
r
r
r
2 = 0.3589 F = 5.60
2 = 0.3518 F = 5.43
2 = 0.3458 F = 5.29
2 = 0.3456 F = 5.28
r
r
r
r
2 = 0.8129 F = 47.80
2 = 0.7190 F = 28.15
2 = 0.6548 F = 20.87
2 = 0.6023 F = 16.66
qf-FHDCA
eFPSA-3
qf-FHBSA
f À VaCvg
PmH ax
eRPCG
SZX
a
qWPSA-1
eLUMO+1
P’’
2 = 0.5038 F = 23.35
MSA
r
2 = 0.3145 F = 4.59
r
2 = 0.5689 F = 14.52
f À Emexax(CH)
5.
r
1CIC—complementary information content (order 1); SZX—ZX Shadow;
a
—Alfa molecular polarizability; qWPSA-1—surface weighted partial positive charged surface area
LUMO+1—energy of the
(PPSA-1) [Semi-MO PC]; MSA—molecular surface area; PmH ax—maximum bond order of a hydrogen atom; eRPCG—relative positive charge [Zefirov’s PC];
e
second lowest unoccupied molecular orbit; P’’—ratio of polarity parameter (difference between the most positive and negative atomic charges in the molecule) to square
distance between the charge extremes—polarity parameter/square distance; qFHDCA—fractional H-donor charged surface area [Semi-MO PC]; eFPSA-3—fractional partial
positive charged surface area (PPSA-3) [Zefirov’s PC]; qFHBSA—fractional H-bonding charged surface area (HBSA) [Semi-MO PC]; VaCvg—average valency of a carbon atom;
max
ex
E
(CH)—maximum exchange energy for a C–H bond.
Note: f- prefix denotes a fragmental descriptor.
of new analogs. Descriptors such as f-Fractional H-bonding
Charged Surface Area (qf-FHBSA, r2 = 0.6548) also confirm the role
of hydrogen bond interactions of fragment.
Surface Area (qFHDCA, r2 = 0.6422), hydrogen bonding interaction
prevail in interaction with active site. Complementary Information
Content (2CIC, r2 = 0.6767) is descriptor that is also chosen among
the most important descriptors, as it was in case of activity on
MDA-MB-453 cells. Polar surface area described by descriptor
Fractional Partial Positive Charged Surface Area is also significant
(eFPSA-3, r2 = 0.7014). For subset 1, fragmental descriptors are also
not the most significant, and the activity of subset mostly depend
on topological factors, described by Average Structural Information
Content (2SICavg, r2 = 0.7905), Average Complementary Information
Content (1CICavg, r2 = 0.7745) and Average Bonding Information
Content (2BICavg, r2 = 0.7569), as well as geometrical factors such
One parameter analysis of descriptors significant for activity on
MDA-MB-361 cells for whole set and subsets 1 and 2 is presented
in Table 3. As for activity on MDA-MB-453 cells, fragmental
descriptors were not selected as the most significant for whole
data set. Regarding the most significant descriptors chosen by heu-
ristic method, such as Fractional H-bonding Charged Surface Area
(qFHBSA, r2 = 0.7154), H-acceptor Dependent H-donor Charged
Surface Area relative to Total Molecular Surface Area (HA-dep
qHDCA-1/TMSA, r2 = 0.6843) and Fractional H-donor Charged

´
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V. Markovic et al. / Bioorg. Med. Chem. Lett. 21 (2011) 4416–4421
Table 3
The most significant descriptors for antiproliferative activity on MDA-MB-361 cells selected by heuristic method
Whole set (n = 25)
1a–1l (n = 12)
1m–1y (n = 13)
1.
2.
3.
4.
5.
r
r
r
r
r
2 = 0.7154 F = 57.81
2 = 0.7014 F = 54.02
2 = 0.6843 F = 49.86
2 = 0.6767 F = 48.13
2 = 0.6422 F = 41.28
qFHBSA
r
r
r
r
r
2 = 0.7905 F = 37.74
2 = 0.7745 F = 34.34
2 = 0.7569 F = 31.13
2 = 0.6659 F = 19.93
2 = 0.6371 F = 17.55
2SICavg
1CICavg
2BICavg
SZX
r
r
r
2 = 0.7776 F = 38.47
2 = 0.6688 F = 22.21
2 = 0.6284 F = 18.60
qf-FHDCA
eFPSA-3
eFPSA-3
HA-dep qHDCA-1/TMSA
f-HA-dep qHDCA-1/TMSA
f-HA-dep qHDCA-2/TMSA
f-qHDSA
2CIC
r2 = 0.5810 F = 15.25
qFHDCA
VC
r
2 = 0.5788 F = 15.11
avg
qFHBSA—fractional H-bonding charged surface area (HBSA) [Semi-MO PC]; eFPSA-3—fractional partial positive charged surface area (PPSA-3) [Zefirov’s PC]; HA-dep qHDCA-1/
TMSA—H-acceptor dependent H-donor charged surface area relative to total molecular surface area (HDCA-1/TMSA) [Semi-MO PC]; 2CIC—complementary information
content (order 2); qFHDCA—fractional H-donor charged surface area [Semi-MO PC]; 2SICavg—average structural information content (order 2); 1CICavg—average comple-
mentary information content (order 1); 2BICavg—average bonding information content (order 2); SZX—ZX Shadow; Vavg—average valency of a carbon atom; HA-dep qHDCA-2/
C
TMSA—H-acceptor dependent H-donor charged surface area relative to total molecular surface area (HDCA-2/TMSA) [Semi-MO PC]; qHDSA—H-donors surface area [Semi-MO
PC].
Note: f- prefix denotes a fragmental descriptor.
as ZX Shadow (SZX, r2 = 0.6659). Concerning subset 2, fractional
References and notes
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Charged Surface Area (qf-FHDCA, r2 = 0.7776), f-H-acceptor Depen-
dent H-donor Charged Surface Area relative to Total Molecular Sur-
face Area (f-HA-dep qHDCA-1/TMSA, r2 = 0.6284), f-H-donors
Surface Area (f-qHDSA, r2 = 0.5788). The correlation coefficients of
those descriptors with activity are pretty high, which again indi-
cates that once the rest of the structure is fixed by additional
hydrophobic interactions of phenyl ring with hypothetical hydro-
phobic pocket of target, and size and shape of molecules basic
selection provides good fitting with active place, the activity on
the target mostly depends on fragment at position 4. Generally,
compounds from subset 2, containing phenyl ring, showed slightly
better activities on both cells tested.
5. Kimata, A.; Nakagawa, H.; Ohyama, R.; Fukuuchi, T.; Ohta, S.; Suzuki, T.; Miyata,
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In conclusion, QSAR analysis supported the hypothesis that
investigated compounds act by inhibiting the enzymes included
in tumorogenesis rather than as free radical scavengers. Heuristic
method showed that the most significant factors for activity of
the compounds are geometrical and topological, including size
and shape of the molecule. It could also be concluded that aromatic
ring at position 1 of pyrazol-5-one plays significant role in hydro-
phobic interactions, whilst substituents connected to amino group
at position 4 mainly interact by formation of hydrogen bonds with
active place.
14. General procedure for the preparation of 1a–1e and 1m–1q.
A mixture of
aldehyde (1.5 mmol), amine (3 mmol) and p-toluenesulphonic acid
monohydrate (0.011 g, 0.06 mmol) in ethanol (10 mL) was heated to reflux
for 2 h. After cooling, the precipitate was filtered off, washed with a little cold
ethanol and dried in vacuo over anhydrous CaCl2.
Acknowledgments
General procedure for the preparation of 1f–1l and 1r–1y. A mixture of aldehyde
(1.5 mmol) and amino acid (1.8 mmol) in ethanol (10 mL) was heated to reflux
for 4 h. After removal of the solvent under reduced pressure, 40 mL of water
was added and the suspension was stirred for additional 1 h at room
The authors are grateful to the Ministry of Science and Techno-
logical Development of the Republic of Serbia for financial support
(Grant Nos 172016 and 175011).
temperature. The precipitate was filtered off, washed with
chloroform and dried in vacuo over anhydrous CaCl2.
a little cold
15. Belmar, J.; Pérez, F. R.; Alderete, J.; Zúñiga, C. J. Braz. Chem. Soc. 2005, 16, 179.
16. Thaker, B. T.; Surati, K. R.; Oswal, S.; Jadeja, R. N.; Gupta, V. K. Struct. Chem.
2007, 18, 295.
Supplementary data
17. Holzer, W.; Kautsch, C.; Laggner, C.; Claramunt, R. M.; Pérez-Torralba, M.;
Alkorta, I.; Elguero, J. Tetrahedron 2004, 60, 6791.
18. Liedtke, C.; Wang, J.; Tordai, A.; Symmans, W. F.; Hortobagyi, G. N.; Kiesel, L.;
Hess, K.; Baggerly, K. A.; Coombes, K. R.; Pusztai, L. Breast Cancer Res. Treat.
2010, 121, 301.
Supplementary data (spectral data, Treatment of tumor cell
lines, Flow cytometry analysis, in vitro angiogenesis assay and
QSAR analysis) associated with this article can be found, in the on-
line version, at doi:10.1016/j.bmcl.2011.06.025.