Synthesis, characterization, and biological evaluation of some novel thiosemicarbazones as possible antibacterial and antioxidant agents

Article abstract of DOI:10.1080/10426507.2013.844139

The synthesis and characterization of 18 novel thiosemicarbazones have been investigated as part of a research program on development of compounds with antibacterial and antioxidant activities. Among the tested compounds, 2-(4-hydroxybenzylidene)-N-[4-(tr

Full text of DOI:10.1080/10426507.2013.844139

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Phosphorus, Sulfur, and Silicon and the Related
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SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL
EVALUATION OF SOME NOVEL THIOSEMICARBAZONES AS
POSSIBLE ANTIBACTERIAL AND ANTIOXIDANT AGENTS
Ayşegül Karaküçük-İyidoğan a , Zeliha Mercan a , Emine Elçin Oruç-Emre a , Demet Taşdemir
a , Derya İşler b , İbrahim Halil Kılıç b & Mehmet Özaslan b
a Department of Chemistry, Faculty of Arts and Sciences , Gaziantep University , Universite
Bulvari, 27310 , Gaziantep , Turkey
b Department of Biology, Faculty of Arts and Sciences , Gaziantep University , Universite
Bulvari, 27310 , Gaziantep , Turkey
Accepted author version posted online: 11 Oct 2013.
To cite this article: Phosphorus, Sulfur, and Silicon and the Related Elements (2013): SYNTHESIS, CHARACTERIZATION AND
BIOLOGICAL EVALUATION OF SOME NOVEL THIOSEMICARBAZONES AS POSSIBLE ANTIBACTERIAL AND ANTIOXIDANT AGENTS,
Phosphorus, Sulfur, and Silicon and the Related Elements
To link to this article: http://dx.doi.org/10.1080/10426507.2013.844139
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SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL EVALUATION OF SOME
NOVEL THIOSEMICARBAZONES AS POSSIBLE ANTIBACTERIAL AND
ANTIOXIDANT AGENTS
Ayşegül Karaküçük-İyidoğana*, Zeliha Mercana, Emine Elçin Oruç-Emrea, Demet
Taşdemira, Derya İşlerb, İbrahim Halil Kılıçb, Mehmet Özaslanb
aDepartment of Chemistry, Faculty of Arts and Sciences, Gaziantep University, Universite
Bulvari, 27310, Gaziantep, Turkey.
bDepartment of Biology, Faculty of Arts and Sciences, Gaziantep University, Universite Bulvari,
27310, Gaziantep, Turkey.
*E-mail: iyidogan@gantep.edu.tr
Phone: +90 342 317 18 30; Fax: +90 342 360 10 32.
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Abstract
The synthesis and characterization of eighteen novel thiosemicarbazones, have been investigated
as part of a research program on development of compounds with antibacterial and antioxidant
activities.
Among
the
tested
compounds,
2-(4-hydroxybenzylidene)-N-[4-
(trifluoromethoxy)phenyl]hydrazine carbothioamide (3g) and 2-(thiophen-2-ylmethylidene)-N-
[4-(morpholin-4-yl)phenyl]hydrazine carbothioamide (4b) showed excellent inhibition potency
at low concentration (0.5 μg/mL) against Gram-positive pathogens (E. faecalis and S. aureus).
All tested compounds were also found to possess antioxidant activity against DPPH radical and
ABTS radical cation.
H
N
H
N
NH2
NCS
N2H4.H2O
Et2O
CSCl2
NH2
NaOH/CHCl3
S
R
R
R
3, 4
1, 2
R'CHO MeCN
H
N
H
N
R'
N
S
R
3a-i, 4a-i
Keywords: antibacterial, antioxidant, isothiocyanate, thiosemicarbazide, thiosemicarbazone.
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INTRODUCTION
Since the discovery of the first antibiotic penicillin by Alexander Fleming in 1928, the
antibiotics have been of critical importance in the fight against infectious diseases caused by
pathogenic microorganisms, such as bacteria, viruses, parasites or fungi.1 However, the
increasing resistance against Gram-positive pathogens and Gram-negative pathogens is a serious
health problem in both developed and developing countries.2,3 Especially, the existence of
methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterecoccus
faecalis (VRE) in the nosocomial (hospital) environments has increased considerably.4
Furthermore, Pseudomonas aeruginosa is an opportunistic human pathogen and naturally
resistant to a wide range of antibiotics.5 Reactive oxygen species (ROS) normally exist in all
aerobic cells in balance with biochemical antioxidants which may be enzymes such as
superoxide dismutate, glutathione peroxidase and catalase or organic molecules such as ascorbic
acid (vitamin C), tocopherols (vitamin E), carotenoids, flavonoids and thiols.6 Oxidative stress is
generated leading to oxidative damages to biomolecules when this critical balance is disrupted
because of excess ROS, antioxidants depletion, or both.7 Various antioxidant agents have been
widely used in food industry and medicine to interrupt radical chain oxidation processes.8
Herein, to find potent more specific and effective antibacterial and antioxidant agents, we
have designed a series of novel compounds containing thiosemicarbazone skeleton.
Thiosemicarbazones are thiourea derivatives and analogues of semicarbazones which contains a
sulfur atom in place of the oxygen atom.9 They have attracted considerable interest since the
discovery of their activity against Mycobacterium tuberculosis.10 The biological properties of
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thiosemicarbazone derivatives such as antibacterial,11 antifungal,12 antimalarial,13 anticancer,14,15
anti-inflammatory,16 anticonvulsant,17 antioxidant,18 antiviral,19,20 activities have been
extensively studied over the last 50 years. Some thiosemicarbazone derivatives, such as triapine
(anticancer), thiacetazone (antitubercular) and methisazone (antiviral) are already used in clinical
treatment (Figure 1.).21 Generally, thiosemicarbazone derivatives are synthesized by
condensation of the corresponding thiosemicarbazides with aldehydes or ketones. Therefore,
their biologicial activities depend on the parent aldehyde and ketone.22
On the basis of the above ideas, novel eighteen thiosemicarbazone derivatives have been
synthesized by condensation of five 4-substituted benzaldeydes and four heteroaromatic
aldehydes with two 4-substitutedphenyl thiosemicarbazides. The chemical structures of all
1
13
compounds including intermediates were eludicated by UV-Vis, IR, H NMR, C NMR, mass
spectra and elemental analysis. These thiosemicarbazones were tested against a variety of bio
assays. Antibacterial activity was evaluated against four pathogenic bacterial strains. Antioxidant
activity of the synthesized thiosemicarbazones was also screened using the 2,2-diphenyl-1-
picrylhydrazyl (DPPH) method and the 2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)
(ABTS) method as free radical scavenging assays. The results showed that novel
thiosemicarbazone analogues possess a great potential to be developed as antibacterial and
antioxidant agents.
[Insert Figure 1]
RESULTS AND DISCUSSION
Synthesis
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The starting compounds, 4-substitutedphenyl isothiocyanates (1 and 2), were prepared by
treatment of 4-substituted aniline derivatives with thiophosgene in the presence of NaOH in
water-chloroform medium at 0°C for 24 h. 4-(trifluoromethoxy)phenyl isothiocyanate (1) and 4-
morpholinophenyl isothiocyanate (2) are commercially avaliable. 4-substitutedphenyl
thiosemicarbazides (3 and 4) were reported previously.23,24 These compounds were obtained by
the reaction of 4-substitutedphenyl isothiocyanates with hydrazine monohydrate in diethyl ether
at room temperature. A series of thiosemicarbazones (3a-i and 4a-i) were synthesized by
refluxing an equimolar ratio of the appropriate aldehydes and 4-substituedphenyl
thiosemicarbazides in acetonitrile medium and gave 80-86% yields. All thiosemicarbazone
derivatives were firstly synthesized. The general synthetic pathway to prepare thiosemicarbazone
derivatives was exhibited in Scheme 1. The chemical structures of the all synthesized
thiosemicarbazones were supported by elemental analysis and the spectral data achieved from
1
UV-Vis, IR, H NMR, 13C NMR and mass spectroscopy which were in agreement with the
proposed structures.
[Insert Scheme 1]
Antibacterial activity
Both series of thiosemicarbazone derivatives, 3a-i and 4a-i were evaluated for their in
vitro antibacterial activity against two Gram-positive (Enterococcus faecalis ATTC 29212 and
Staphylococcus aureus ATTC 25923) and two Gram-negative (Escherichia coli ATTC 25322
and Pseudomonas aeruginosa ATTC 27853) bacteria using conventional microdilution broth
method.25 The MIC (Minimum Inhibitory Concentration) values were determined by comparison
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to ampicillin trihydrate as a reference drug. The results of antibacterial activity study were
presented in Table S 1 (Supplemental Materials).
DPPH radical scavenging activity
The scavenging effect of the synthesized thiosemicarbazones 3a-i and 4a-i on the DPPH
radical was evaluated by modifying the literature procedure.26 The results of antioxidant activity
study were presented in Table S 2 (Supplemental Materials).
ABTS radical cation scavenging activity
In ABTS radical cation scavenging method, the antioxidant activity of tested compounds
was expressed also as the TEAC, the concentration of Trolox solution having an antioxidant
activity equivalent to 1 mM concentration of the tested compounds.27
Determination of drug-like properties
In order to improve the discovery and development of new drug candidates, a broad effort
is being made to assess the ‘drug-like’ properties of molecules in early stages of the discovery-
research process.28,29 Lipinski's rule of five also known as the Rule of Five (ROF) is a rule of
thumb to evaluate druglikeness or determine if a chemical compound with a certain
pharmacological or biological activity has properties that would make it a likely orally active
drug in humans. The rule was formulated by the medical chemist Christopher A. Lipinski and his
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colleagues in 1997, based on the observation that most medication drugs are relatively small and
lipophilic molecules. The rule describes molecular properties of a compound that directly
influence its pharmacokinetics in human body like a drug, including their absorption,
distrubution, metabolism and excretion (ADME). Generally, the ROF is based on four properties
of molecules: molecular weight (MW), octanol-water partition coefficient (logP), the number of
hydrogen-bond donors (HBD: the number of –OH and –NH groups) and the number of
hydrogen-bond acceptors (HBA: the number of oxygen and nitrogen atoms). These parameters
allow to ascertain a poor oral absorption, or membrane permeability, that occurs when the tested
compounds present values higher than five H-bond donors, 10 H-bond acceptors, molecular
weight is greater than 500 Da and lipophilicity (clogP) is greater than 5.29 However, it is
important to note that the rule does not guarantee a molecule is drug-like and predict if a
compound is pharmacologically active. Another very useful parameter for the prediction of
absorption is the polar surface area (PSA) defined as the sum of surfaces of polar atoms in a
molecule. This parameter is easy to understand and, most importantly, provides good correlation
with experimental transport data. Topolocigal polar surface area (TPSA) is a good descriptor for
prediction of drug transport properties in the human intestines, Caco-2 monolayers penetration
and blood-brain barrier crossing.30
These parameters were determined for the thiosemicarbazone derivatives in analysis and
the results are given in Table 1. From the obtained data, all thiosemicarbazone derivatives
possess a suitable number of H-bond donor and H-bond acceptor atoms to ensure efficient
interaction with receptors and their logP were found less than 5 except for compound 3h.
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According to predictive TPSA data of all thiosemicarbazones, they could have a good ability for
penetrating cell membranes.
[Insert Table 1]
EXPERIMENTAL
All chemicals and solvents were purchased from Merck and Aldrich Chemical Company
and were used without further purification. Reactions were monitored by thin layer
chromatography (TLC). TLC was performed on Merck Silica Gel 60 F254 plates with
visualization by exposure to iodine vapor and UV-light using EtOAc/hexane (v/v 1:1 and 1:3) as
solvent system. Melting points were determined on a EZ-Melt MPA120 Automated Melting
Point apparatus and were uncorrected. Electronic spectra were recorded in DMF on a PG
Instruments T80+ UV-visible Spectrophometer. IR spectra were recorded on a Perkin Elmer 100
1
FT IR Spectrometer with universal ATR sampling accessory. H NMR and 13C NMR spectra
were obtained at room temperature with a Bruker Avance-DPX-400 NMR spectrometer in
DMSO-d6 using TMS as a internal standard. Chemical shifts were recorded in parts per million
1
(ppm) downfield from tetramethylsilane. The splitting patterns of H NMR were designed as
follows: s: singlet, brs: broad singlet, d: doublet, dd: double doublet, t: triplet, m: multiplet. The
coupling constants (J) are given in Hertz. The mass spectra were recorded on LC–MS-Agilent
1100 MSD series in the electrospray mode. Elemental analyses (CHNS) were performed on a
VarioMICRO elemental analyzer.
General procedure for the synthesis of thiosemicarbazones (3a-i and 4a-i)
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To a hot solution of thiosemicarbazide (1.20 mmol) in CH3CN (30 mL) was added
dropwise a solution of the an appropriate aldehyde (1.20 mmol) in CH3CN (10 mL) with
continuous stirring and the reaction mixture was refluxed for a period of time specific to each
synthesized compound. The progress of the reaction was monitored by TLC using appropriate
thiosemicarbazide and aldehyde as the reference standard. The reaction mixture was cooled. The
precipitate was filtered and the filtrate was concentrated under reduced pressure. The crude
product was recrystallized from acetonitrile.
2-(furan-2-ylmethylidene)-N-[4-trifluoromethoxy)phenyl]hydrazine carbothioamide
(3a). Brown solid. Yield: 89%; m.p.: 139-140 oC. UV/Vis λmax (nm): 332; 269. IR νmax (cm-1):
1
3295, 3134 (N-H); 1539 (C=N); 1199 (C-F); 1132 (C-N); 1016 (N-N); 750 (C=S). H NMR
(DMSO-d6, δ ppm): 11.91 (s, 1H, CSNH); 9.99 (s, 1H, PhNH); 8.09 (s, 1H, HC=N); 7.87 (d, 1H,
ArH, J=1.59 Hz, C2 proton of furan ring); 7.72 (d, 2H, ArH, J=8.97 Hz, meta protons to OCF3);
7.35 (d, 2H, ArH, J=8.46 Hz, ortho protons to OCF3); 7.09 (d, 1H, ArH, J=3.41 Hz, C4 proton of
furan ring); 6.67 (dd, 1H, ArH, J1=3.42 Hz, J2=1.76 Hz, C3 proton of furan ring). 13C NMR
(DMSO-d6, δ ppm): 176.5 (C=S); 146.2 (ArC, ipso carbon to OCF3); 139.4 (HC=N); 136.1,
130.5, 128.9 (ArC), 127.7 (OCF3), 122.0, 120.3, 119.6 (ArC). MS-ES: (m/z) 329 [M+], 330
[M+H]+. Analysis calculated for C13H10F3N3O2S (329.30): C, 47.42; H, 3.06; N, 12.76; S, 9.74%.
Found: C, 47.48; H, 3.10; N, 12.71; S, 9.67%.
2-(thiophen-2-ylmethylidene)-N-[4-(trifluoromethoxy)phenyl]hydrazine
carbothioamide (3b). Brown solid. Yield: 86%; m.p.: 181-182 oC. UV/Vis λmax (nm): 349; 269.
IR νmax (cm-1): 3379, 3134 (N-H); 1541 (C=N); 1203 (C-F); 1138 (C-N); 1018 (N-N); 749 (C=S);
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1
690 (C-S-C). H NMR (DMSO-d6, δ ppm): 11.91 (s, 1H, CSNH); 9.93 (s, 1H, PhNH); 8.37 (s,
1H, HC=N); 7.71 (d, 1H, ArH, J=3.75 Hz, C2 proton of thiophene ring); 7.67 (d, 2H, ArH,
J=8.74 Hz, meta protons to OCF3); 7.54 (d, 1H, ArH, J=3.70 Hz, C4 proton of thiophene ring);
7.36 (d, 2H, ArH, J=8.71 Hz, ortho protons to OCF3); 7.15 (t, 1H, ArH, J1=3.75 Hz, J2=3.71 Hz,
C3 proton of thiophene ring). 13C NMR (DMSO-d6, δ ppm): 176.2 (C=S); 145.7 (ArC, ipso
carbon to OCF3); 140.9 (HC=N); 138.7, 131.6, 129.9 (ArC), 128.5 (OCF3), 121.9, 121.2, 119.3
(ArC). MS-ES (m/z): 345 [M+], 346 [M+H]+. Analysis calculated for C13H10F3N3OS2 (345.37):
C, 45.21; H, 2.92; N, 12.17; S, 18.57%. Found: C, 45.25; H, 2.89; N, 12.11; S, 18.61%.
2-(5-nitrothiophen-2-ylmethylidene)-N-[4-trifluoromethoxy)phenyl]hydrazine
carbothioamide (3c). Yellow solid. Yield: 81%; m.p.: 223-224 oC. UV/Vis λmax (nm): 400; 296;
270. IR νmax (cm-1): 3333, 3118 (N-H); 1542 (C=N); 1528 (NO2, asymmetric); 1335 (NO2,
1
symmetric); 1227 (C-F); 1153 (C-N); 1024 (N-N); 812 (C=S); 739 (C-S-C). H NMR (DMSO-
d6, δ ppm): 12.30 (s, 1H, CSNH); 10.25 (s, 1H PhNH,); 8.32 (s, 1H, HC=N); 8.12 (d, 1H, ArH,
J= 4.35 Hz, C3 proton of thiophene ring); 7.65 (d, 2H, ArH, J= 8.75 Hz, meta protons to OCF3);
7.62 (d, 1H, ArH, J=4.39 Hz, C4 proton of thiophene ring); 7.39 (d, 2H, ArH, J=8.77 Hz, ortho
protons to OCF3). 13C NMR (DMSO-d6, δ ppm): 176.9 (C=S); 151.6 (ArC, ipso carbon to NO2);
146.7 (ArC, ipso carbon to OCF3); 146.1 (ArC); 138.5 (HC=N); 136.6, 130.8, 130.3 (ArC),
128.4 (OCF3), 121.3, 119.3 (ArC). MS-ES (m/z): 390 [M+], 391 [M+H]+. Analysis calculated for
C13H9F3N4O3S2 (390.37): C, 40.00; H, 2.32; N, 14.35; S, 16.43%. Found: C, 40.16; H, 2.43; N,
14.24; S, 16.48%.
2-(1H-pyrrol-2-ylmethylidene)-N-[4-(trifluoromethoxy)phenyl]hydrazine
o
carbothioamide (3d). Black solid. Yield: 87%; m.p: 165-166 C. UV/Vis λmax (nm): 350; 270.
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IR νmax (cm-1): 3299, 3248, 3146 (N-H); 1555 (C=N); 1167 (C-F); 1122 (C-N); 1016 (N-N); 733
(C=S). 1H NMR (DMSO-d6, δ ppm): 11.79 (s, 1H, CSNH); 11.52 (s, 1H, pyrrole NH); 10.11 (s,
1H, PhNH); 7.96 (s, 1H, HC=N); 7.75 (d, 2H, ArH, J=8.27 Hz, meta protons to OCF3); 7.40 (d,
2H, ArH, J=8.28 Hz, ortho protons to OCF3); 7.08 (m, 1H, ArH, C2 proton of pyrrole ring); 6.50
(m, 1H, ArH, C4 proton of pyrrole ring); 6.15 (m, 1H, ArH, C3 proton of pyrrole ring). 13C NMR
(DMSO-d6, δ ppm): 177.2 (C=S), 144.7 (ArC, ipso carbon to OCF3), 142.9 (C=N), 138.5, 130.1,
129.1 (ArC), 127.4 (OCF3), 125.26, 118.8, 114.7, 111.4 (ArC). MS-ES (m/z): 328 [M+], 329
[M+H]+. Analysis calculated for C13H11F3N4OS (328.32): C, 47.56; H, 3.38; N, 17.07; S, 9.77%.
Found: C, 47.58; H, 3.28; N, 17.11; S, 9.87%.
2-(4-fluorobenzylidene)-N-[4-(trifluoromethoxy)phenyl]hydrazinecarbothioamide
(3e). Brown solid. Yield: 85%; m.p.: 172-173 oC. UV/Vis λmax (nm): 332; 270. IR νmax (cm-1):
1
3291, 3152 (N-H); 1559 (C=N); 1150 (C-F); 1071 (C-N); 1014 (N-N); 830 (C=S). H NMR
(DMSO-d6, δ ppm): 11.94 (s, 1H, CSNH); 10.21 (s, 1H, PhNH); 8.17 (s, 1H, HC=N); 8.00 (dd,
2H, ArH, J=8.52 Hz, ortho protons to F); 7.70 (d, 2H, ArH, J=8.64 Hz, meta protons to OCF3);
7.36 (d, 2H, ArH, J=8.60 Hz, ortho protons to OCF3); 7.28 (t, 2H, ArH, J=8.51 Hz, meta protons
13
to F). C NMR (DMSO-d6, δ ppm): 176.9 (C=S), 164.2 (ArC, ipso carbon to F), 146.7 (ArC,
ipso carbon to OCF3), 141.7 (C=N), 133.4, 131.8, 129.9 (ArC), 127.5 (OCF3), 125.4, 117.7,
114.2 (ArC). MS-ES (m/z): 357 [M+], 358 [M+H]+. Analysis calculated for C15H11F4N3OS
(357.33): C, 50.42; H, 3.10; N, 11.76; S, 8.97%. Found: C, 50.58; H, 3.16; N, 11.67; S, 8.99%.
2-(4-nitrobenzylidene)-N-[4-(trifluoromethoxy)phenyl]hydrazinecarbothioamide
(3f). Yellow solid. Yield: 82%; m.p.: 227-228 oC. UV/Vis λmax (nm): 383; 275; 270. IR νmax (cm-
1): 3345, 3133 (N-H); 1539 (C=N); 1512 (NO2, asymmetric); 1337 (NO2, symmetric); 1161 (C-
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1
F); 1088 (C-N); 1019 (N-N); 749 (C=S). H NMR (DMSO-d6, δ ppm): 12.19 (s, 1H, CSNH);
10.38 (s, 1H, PhNH); 8.27 (s, 1H, HC=N); 8.26 (d, 2H, ArH, J=8.91 Hz, ortho protons to NO2);
8.19 (d, 2H, ArH, J=8.95 Hz, meta protons to NO2); 7.68 (d, 2H, ArH, J=8.96 Hz, meta protons
to OCF3); 7.40 (d, 2H, ArH, J=8.25 Hz, ortho protons to OCF3). 13C NMR (DMSO-d6, δ ppm):
176.5 (C=S), 151.3 (ArC, ipso carbon to NO2), 145.4 (ArC, ipso carbon to OCF3), 141.9 (C=N),
139.0, 130.5, 129.7 (ArC), 127.5 (OCF3), 125.9, 124.8, 114.7 (ArC). MS-ES (m/z): 384 [M+],
385 [M+H]+. Analysis calculated for C15H11F3N4O3S (384.34): C, 46.88; H, 2.88; N, 14.58; S,
8.34%. Found: C, 46.65; H, 2.82; N, 14.29; S, 8.15%.
2-(4-hydroxybenzylidene)-N-[4-(trifluoromethoxy)phenyl]hydrazine carbothioamide
(3g). Yellow solid. Yield: 89%; m.p.: 193-194 oC. UV/Vis λmax (nm): 336; 270. IR νmax (cm-1):
1
3305, 3290 (N-H); 1541 (C=N); 1160 (C-F); 1092 (C-N); 1020 (N-N); 831 (C=S). H NMR
(DMSO-d6, δ ppm): 11.76 (s, 1H, CSNH); 10.07 (s, 1H, PhNH); 9.94 (s, 1H, OH); 8.08 (s, 1H,
HC=N); 7.73 (d, 2H, ArH, J=8.38 Hz, meta protons to OH); 7.71 (d, 2H, ArH, J=8.87 Hz, meta
protons to OCF3); 7.36 (d, 2H, ArH, J=8.63 Hz, ortho protons to OCF3); 6.83 (d, 2H, ArH,
13
J=8.60 Hz, ortho protons to OH). C NMR (DMSO-d6, δ ppm): 177.8 (C=S), 153.5 (ArC, ipso
carbon to OH), 147.2 (ArC, ipso carbon to OCF3), 142.0 (C=N), 132.5, 131.9, 130.2 (ArC),
127.2 (OCF3), 126.1, 117.5, 115.5 (ArC). MS-ES (m/z): 355 [M+], 356 [M+H]+. Analysis
calculated for C15H12F3N3O2S (355.34): C, 50.70; H, 3.40; N, 11.83; S, 9.02%. Found: C, 50.57;
H, 3.55; N, 11.78; S, 9.05%.
2-{4-[bis(2-chloroethyl)amino]benzylidene}-N-[4-(trifluoromethoxy)phenyl]
hydrazine carbothioamide (3h). Brown solid. Yield: 88%; m.p.: 191-192 oC. UV/Vis λmax (nm):
371; 270. IR νmax (cm-1): 3310, 3143 (N-H); 1544 (C=N); 1189 (C-F); 1056 (C-N); 1017 (N-N);
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1
815 (C=S); 717 (C-Cl). H NMR (DMSO-d6, δ ppm): 11.78 (s, 1H, CSNH); 10.18 (s, 1H,
PhNH); 8.12 (s, 1H, HC=N); 7.79 (d, 4H, ArH, J=8.86 Hz, ortho and meta protons to
N(CH2CH2Cl)2 group); 7.42 (d, 2H, ArH, J=8.50 Hz, meta protons to OCF3); 6.86 (d, 2H, ArH,
J=8.91 Hz, ortho protons to OCF3); 3.89-3.79 (m, 8H, N(CH2CH2Cl)2). 13C NMR (DMSO-d6, δ
ppm): 175.9 (C=S), 148.4 (ArC, ipso carbon to N(CH2CH2Cl)2 group), 146.8 (ArC, ipso carbon
to OCF3), 1439 (C=N), 136.7, 134.56 129.7 (ArC), 127.4 (OCF3), 126.1, 122.6, 112.0 (ArC),
52.3 (N(CH2CH2Cl)2), 41.9 (N(CH2CH2Cl)2). MS-ES: (m/z) 478 [M+]; 479 [M+H]+. Analysis
calculated for C19H19Cl2F3N4OS (478.35): C, 47.61; H, 4.00; N, 11.69; S, 6.69%. Found: C,
47.48; H, 4.07; N, 11.62; S, 6.74%.
2-(4-methoxybenzylidene)-N-[4-(trifluoromethoxy)phenyl]hydrazine
carbothioamide (3i). Beige solid. Yield: 79%; m.p.: 165-166 oC. UV/Vis λmax (nm): 346; 270.
IR νmax (cm-1): 3343, 3143 (N-H); 1543 (C=N); 1166 (C-F); 1132 (C-N); 1024 (N-N); 829 (C=S).
1H NMR (DMSO-d6, δ ppm): 11.82 (s, 1H, CSNH); 10.12 (s, 1H, PhNH); 8.12 (s, 1H, HC=N);
7.85 (d, 2H, ArH, J=8.85 Hz, meta protons to OCH3); 7.71 (d, 2H, ArH, J=8.97 Hz, meta protons
to OCF3); 7.37 (d, 2H, ArH, J=8.90 Hz, ortho protons to OCF3); 6.90 (d, 2H, ArH, J=8.86 Hz,
ortho protons to OCH3); 3.81 (s, 3H, OCH3). 13C NMR (DMSO-d6, δ ppm): 176.3 (C=S), 161.3
(ArC, ipso carbon to OCH3), 147.3 (ArC, ipso carbon to OCF3), 143.4 (C=N), 136.7, 134.8,
129.7 (ArC), 127.8 (OCF3), 126.7, 126.1, 114.5 (ArC), 55.3 (OCH3). MS-ES (m/z): 369 [M+],
370 [M+H]+. Analysis calculated for C16H14F3N3O2S (369.37): C, 52.03; H, 3.82; N, 11.38; S,
8.68%. Found: C, 52.06; H, 3.76; N, 11.44; S, 8.80%.
2-(furan-2-ylmethylidene)-N-[4-(morpholin-4-yl)phenyl]hydrazine carbothioamide
(4a). Brown solid. Yield: 72%; m.p.: 219-220 oC. UV/Vis λmax (nm): 331; 271. IR νmax (cm-1):
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1
3286, 3193 (N-H); 1564 (C=N); 1069 (C-N), 1018 (N-N); 811 (C=S). H NMR (DMSO-d6, δ
ppm): 11.69 (s, 1H, CSNH); 9.67 (s, 1H, PhNH); 8.07 (s, 1H, HC=N); 7.85 (d, 1H, ArH, J=1.60
Hz, C2 proton of furan ring); 7.38 (d, 2H, ArH, J=8.96 Hz, meta protons to morpholino group);
7.07 (d, 1H, ArH, J=3.60 Hz, C4 proton of furan ring); 6.92 (d, 2H, ArH, J=8.65 Hz, ortho
protons to morpholino group); 6.65 (dd, 1H, ArH, J1=3.60 Hz, J2=1.60 Hz, C3 proton of furan
13
ring); 3.74 (t, 4H, NCH2CH2O); 3.11 (t, 4H, NCH2CH2O). C NMR (DMSO-d6, δ ppm): 176.4
(C=S), 151.9, 146.1 (ArC), 143.4 (C=N), 130.8, 129.7, 127.9, 116.4, 113.7, 113.3 (ArC), 66.4
(NCH2CH2O), 47.2 (NCH2CH2O). MS-ES (m/z): 330 [M+], 331 [M+H]+. Analysis calculated for
C16H18N4O2S (330.41): C, 58.16; H, 5.49; N, 16.96; S, 9.70%. Found: C, 58.29; H, 5.47; N,
16.81; S, 9.58%.
2-(thiophen-2-ylmethylidene)-N-[4-(morpholin-4-yl)phenyl]hydrazine
carbothioamide (4b). Dark green solid. Yield: 72%; m.p.: 195-196 oC. UV/Vis λmax (nm): 355;
268. IR νmax (cm-1): 3220, 3100 (N-H); 1542 (C=N); 1135 (C-N); 1041 (N-N); 819 (C=S); 714
1
(C-S-C). H NMR (DMSO-d6, δ ppm): 11.75 (s, 1H, CSNH); 9.70 (s, 1H PhNH); 8.32 (s, 1H,
HC=N); 7.69 (d, 1H, ArH, J=3.81 Hz C2 proton of thiophene ring); 7.52 (d, 1H, ArH, J=3.64 Hz
C4 proton of thiophene ring); 7.36 (d, 2H, ArH, J=8.82 Hz, meta protons to morpholino group);
7.14 (dd, 1H, ArH, J1=3.80 Hz, J2=3.62 Hz, C3 proton of thiophene ring); 6.93 (d, 2H, ArH,
J=8.81 Hz, ortho protons to morpholino group); 3.75 (t, 4H, NCH2CH2O); 3.11 (t, 4H,
NCH2CH2O). 13C NMR (DMSO-d6, δ ppm): 176.5 (C=S), 154.5 (ArC), 141.7 (C=N), 135.6,
132.6, 130.8, 129.1, 121.8, 116.5, 113.7 (ArC), 66.4 (NCH2CH2O), 47.3 (NCH2CH2O). MS-ES:
(m/z) 346 [M+], 347 [M+H]+. Analysis calculated for C16H18N4OS2 (346.48): C, 55.47; H, 5.24;
N, 16.17; S, 18.51%. Found: C, 55.17; H, 5.12; N, 16.09; S, 18.63%.
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2-(5-nitrothiophene-2-ylmethylidene)-N-[4-(morpholin-4-yl)phenyl]hydrazine
carbothioamide (4c). Brown solid. Yield: 74%; m.p.: 230-231 oC. UV/Vis λmax (nm): 398; 291;
270. IR νmax (cm-1): 3344, 3107 (N-H); 1543 (C=N); 1518 (NO2, asymmetric); 1334 (NO2,
1
symmetric); 1119 (C-N); 1032 (N-N); 813 (C=S); 730 (C-S-C). H NMR (DMSO-d6, δ ppm):
12.11 (s, 1H, CSNH); 10.07 (s, 1H PhNH,); 8.28 (s, 1H, HC=N); 8.11 (d, 1H, ArH, J= 4.40 Hz,
C3 proton of thiophene ring); 7.60 (d, 1H, ArH, J= 4.40 Hz, C4 proton of thiophene ring,); 7.32
(d, 2H, ArH, J=8.80 Hz, meta protons to morpholino group); 6.95 (d, 2H, ArH, J=8.80 Hz, ortho
13
protons to morpholino group); 3.75 (t, 4H, NCH2CH2O); 3.12 (t, 4H, NCH2CH2O). C NMR
(DMSO-d6, δ ppm): 176.8 (C=S); 151.33 (ArC, ipso carbon to NO2); 149.5, 147.1, (ArC); 135.8
(HC=N); 131.0, 130.8, 129.9, 127.5, 115.0 (ArC), 66.6 (NCH2CH2O), 49.0 (NCH2CH2O). MS-
ES (m/z): 391 [M+], 392 [M+H]+. Analysis calculated for C16H17N5O3S2 (391.48): C, 49.09; H,
4.38; N, 17.89; S, 16.38%. Found: C, 49.21; H, 4.49; N, 17.65; S, 16.42%.
2-(1H-pyrrol-2-ylmethylidene)-N-[4-(morpholin-4-yl)phenyl]hydrazine
carbothioamide (4d). Orange solid. Yield: 65%; m.p: 175-176 oC. UV/Vis λmax (nm): 348; 269.
1
IR νmax (cm-1): 3280, 3254, 3123 (N-H); 1579 (C=N); 1123 (C-N); 1027 (N-N); 813 (C=S). H
NMR (DMSO-d6, δ ppm): 11.54 (s, 1H, CSNH); 11.52 (s, 1H, pyrrole NH); 9.90 (s, 1H, PhNH);
7.94 (s, 1H, HC=N); 7.40 (d, 2H, ArH, J=8.40 Hz, meta protons to morpholino group); 7.04
(brs, 1H, ArH, C2 proton of pyrrole ring); 6.97 (d, 2H, ArH, J= 8.40 Hz, ortho protons to
morpholino group); 6.46 (brs, 1H, ArH, C4 proton of pyrrole ring); 6.15 (t, 1H, ArH, C3 proton
13
of pyrrole ring); 3.76 (t, 4H, NCH2CH2O); 3.12 (t, 4H, NCH2CH2O). C NMR (DMSO-d6, δ
ppm): 176.9 (C=S), 145.7 (ArC), 142.3 (C=N), 132.7, 128.4, 127.1, 124.8, 119.2, 113.2, 111.0
(ArC), 66.4 (NCH2CH2O), 48.1 (NCH2CH2O). MS-ES (m/z): 329 [M+], 330 [M+H]+. Analysis
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calculated for C16H19N5OS (329.43): C, 58.34; H, 5.81; N, 21.26; S, 9.73%. Found: C, 58.26; H,
5.77; N, 21.12; S, 9.61%.
2-(4-fluorobenzylidene)-N-[4-(morpholin-4-yl)phenyl]hydrazinecarbothioamide (4e).
o
Gray solid. Yield: 88%; m.p.: 217-218 C. UV/Vis λmax (nm): 332; 269. IR νmax (cm-1): 3257,
1
3118 (N-H); 1541 (C=N); 1230 (C-F); 1118 (C-N); 1071 (N-N); 824 (C=S). H NMR (DMSO-
d6, δ ppm): 11.52 (s, 1H, CSNH); 10.01 (s, 1H PhNH); 8.13 (s, 1H, HC=N); 7.99 (dd, 2H, ArH,
J=8.65 Hz ortho protons to F); 7.35 (d, 2H, ArH, J=8.65 Hz, meta protons to morpholino group);
7.27 (t, 2H, ArH, J=8.55 Hz, meta proton to F); 6.94 (d, 2H, ArH, J=8.67 Hz, ortho protons to
morpholino group); 3.74 (t, 4H, NCH2CH2O); 3.10 (t, 4H, NCH2CH2O). 13C NMR (DMSO-d6, δ
ppm): 176.9 (C=S), 162.4, 154.6 (ArC), 142.8 (C=N), 132.2, 131.4, 130.8, 128.0, 116.5, 113.5
(ArC), 66.6 (NCH2CH2O), 47.6 (NCH2CH2O). MS-ES (m/z): 358 [M+], 359 [M+H]+. Analysis
calculated for C18H19FN4OS (358.44): C, 60.32; H, 5.34; N, 15.63; S, 8.95%. Found: C, 60.24;
H, 5.32; N, 15.31; S, 8.83%.
2-(4-nitrobenzylidene)-N-[4-(morpholin-4-yl)phenyl]hydrazinecarbothioamide (4f).
Yellow solid. Yield: 75%; m.p.: 180-181 oC. UV/Vis λmax (nm): 392; 276; 268. IR νmax (cm-1):
3279, 3254 (N-H); 1579 (C=N); 1518 (NO2, asymmetric); 1345 (NO2, symmetric); 1122 (C-N);
1
1027 (N-N); 814 (C=S). H NMR (DMSO-d6, δ ppm): 12.01 (s, 1H, CSNH); 10.22 (s, 1H,
PhNH); 8.25 (d, 2H, ArH, J=8.91 Hz, ortho protons to NO2); 8.21 (s, 1H, HC=N); 8.19 (d, 2H,
ArH, J=8.95 Hz, meta protons to NO2); 7.34 (d, 2H, ArH, J=8.40 Hz, meta protons to
morpholino group); 6.96 (d, 2H, ArH, J=8.40 Hz, ortho protons to morpholino group); 3.76 (t,
13
4H, NCH2CH2O); 3.12 (t, 4H, NCH2CH2O). C NMR (DMSO-d6, δ ppm): 177.3 (C=S), 151.9
(ArC, ipso carbon to NO2), 147.5 (ArC). 142.2 (C=N), 140.2, 128.6, 127.5, 125.1, 124.9, 113.3
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(ArC), 67.1 (NCH2CH2O), 48.2 (NCH2CH2O). MS-ES (m/z): 385 [M+], 386 [M+H]+. Analysis
calculated for C18H19N5O3S (385.45): C, 56.09; H, 4.97; N, 18.17; S, 8.32%. Found: C, 56.15; H,
4.91; N, 18.28; S, 8.44%.
2-(4-hydroxybenzylidene)-N-[4-(morpholin-4-yl)phenyl]hydrazinecarbothioamide
(4g). Brown solid. Yield: 86%; m.p.: 230-231 oC. UV/Vis λmax (nm): 329; 270. IR νmax (cm-1):
1
3297, 3192 (N-H); 1577 (C=N); 1065 (C-N); 1024 (N-N); 812 (C=S). H NMR (DMSO-d6, δ
ppm): 11.54 (s, 1H,CSNH); 9.91 (s, 1H, PhNH); 9.83 (s, 1H, OH); 8.04 (s, 1H, HC=N); 7.71 (d,
2H, ArH, J=8.89 Hz, meta protons to OH); 7.36 (d, 2H, ArH, J=8.58 Hz, meta protons to
morpholino group); 6.92 (d, 2H, ArH, J=8.56 Hz, ortho protons to morpholino group); 6.85 (d,
2H, ArH, J=8.87 Hz, ortho protons to OH); 3.74 (t, 4H, NCH2CH2O); 3.10 (t, 4H, NCH2CH2O).
13C NMR (DMSO-d6, δ ppm): 178.2 (C=S), 156.6, 149.3 (ArC), 141.5 (C=N), 127.9, 126.4,
125.2, 124.4, 122.7, 112.7 (ArC), 66.3 (NCH2CH2O), 47.3 (NCH2CH2O). MS-ES (m/z): 356
[M+]; 357 [M+H]+. Analysis calculated for C18H20N4O2S (356.45): C, 60.65; H, 5.66; N, 15.72;
S, 9.00%. Found: C, 60.55; H, 5.57; N, 15.60; S, 9.16%.
2-{4-[bis(2-chloroethyl)amino]benzylidene}-N-[4-(morpholin-4-yl)phenyl]
hydrazine carbothioamide (4h). Red solid. Yield: 85%; m.p.: 184-185 oC. UV/Vis λmax (nm):
377; 271. IR νmax (cm-1): 3280, 3255 (N-H); 1595 (C=N); 1122 (C-N); 1027 (N-N); 814 (C=S);
698 (C-Cl). 1H NMR (DMSO-d6, δ ppm): 11.53 (s, 1H, CSNH); 9.81 (s, 1H, PhNH); 8.03 (s, 1H,
HC=N); 7.72 (d, 4H, ArH, J=8.86 Hz, meta protons to N(CH2CH2Cl)2 group); 7.38 (d, 2H, ArH,
J=8.50 Hz, meta protons to morpholino group); 6.93 (d, 2H, ArH, J=8.91 Hz, ortho protons to
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morpholino group); 6.79 (d, 2H, ArH, J=8.91, ortho protons to N(CH2CH2Cl)2 group); 3.80-3.74
13
(m, 12H, N(CH2CH2Cl)2 and NCH2CH2O); 3.11 (t, 4H, NCH2CH2O). C NMR (DMSO-d6, δ
ppm): 176.7 (C=S), 150.4 (ArC, ipso carbon to N(CH2CH2Cl)2 group), 145.5 (ArC), 142.4
(C=N), 130.8, 128.7, 127.3, 124.8, 114.4, 111.5 (ArC), 65.96 (NCH2CH2O), 53.3
(N(CH2CH2Cl)2), 48.1 (NCH2CH2O), 42.1 (N(CH2CH2Cl)2). MS-ES: (m/z) 479 [M+]; 480
[M+H]+. Analysis calculated for C22H27Cl2N5OS (479.47): C, 55.00; H, 5.66; N, 14.58; S,
6.67%. Found: C, 55.07; H, 5.71; N, 14.46; S, 6.69%.
2-(4-methoxybenzylidene)-N-[4-(morpholin-4-yl)phenyl]hydrazine carbothioamide
o
(4i). Beige solid. Yield: 80%; m.p.: 195-196 C. UV/Vis λmax (nm): 352; 269. IR νmax (cm-1):
1
3280, 3254 (N-H); 1579 (C=N); 1123 (C-N); 1026 (N-N); 814 (C=S). H NMR (DMSO-d6, δ
ppm): 11.62 (s, 1H, CSNH); 9.91 (s, 1H, PhNH); 8.09 (s, 1H, HC=N); 7.88 (d, 2H, ArH, J=8.85
Hz, meta protons to OCH3);.7.38 (d, 2H, ArH, J=8.90 Hz, meta protons to morpholino group);
7.02 (d, 2H, ArH, J=8.90 Hz, ortho protons to morpholino group); 6.98 (d, 2H, ArH, J=8.86 Hz,
ortho protons to OCH3); 3.80 (s, 3H, OCH3,); 3.73 (t, 4H, NCH2CH2O); 3.11 (t, 4H,
NCH2CH2O). 13C NMR (DMSO-d6, δ ppm): 175.5 (C=S), 162.9 (ArC, ipso carbon to OCH3),
144.2 141.2 (C=N), 131.5, 128.4, 127.0, 126.9, 115.1, 113.7 (ArC), 67.6 (NCH2CH2O), 56.2
(OCH3), 48.8 (NCH2CH2O). MS-ES (m/z): 370 [M+], 371 [M+H]+. Analysis calculated for
C19H22N4O2S (370.48): C, 61.60; H, 5.99; N, 15.12; S, 8.66%. Found: C, 61.76; H, 5.82; N,
15.36; S, 8.81%.
Biological studies
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All the synthesized thiosemicarbazones (3a-i and 4a-i) were evaluated for their
antibacterial and antioxidant activities.
Antibacterial activity assay
Antibacterial activity of all synthesized thiosemicarbazones were sreened against two
Gram-positive (Enterococcus faecalis ATTC 29212 and Staphylococcus aureus ATTC 25923)
and two Gram-negative (Escherichia coli ATTC 25322 and Pseudomonas aeruginosa ATTC
27853) bacteria. The minimum inhibitory concentration (MIC) values for thiosemicarbazone
derivatives (3a-i, 4a-i) defined as the lowest concentration of the compounds preventing the
visible growth were determined by using the microdilution broth procedure.31
Antioxidant activity assay
DPPH radical scavenging capacity assay
The 2,2-diphenyl-1-picrylhydrazyl (DPPH.).is a stable radical and commercially
available. It is characterized by an absortion band at 518 nm and its reduction by an antioxidant
compound leads to a decolorisation which can be determined by UV-Vis spectrofotometer. The
scavenging effect of the synthesized thiosemicarbazones 3a-i and 4a-i on the DPPH radical was
evaluated by modifying the literature procedure.32
ABTS radical cation scavenging capacity assay
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A common method for testing the antioxidative potential of antioxidants as hydrogen-
donating agents is to measure their ability to scavenge ABTS.+radical cation.32,33
CONCLUSIONS
The synthesis, structural characterization, antibacterial and antioxidant evaluation of
eighteen novel thiosemicarbazone derivatives have been reported. All synthesized compounds
were purified by recrystallization and obtained in good yields. The spectroscopic data of
thiosemicarbazones 3a-i and 4a-i clearly identified the proposed chemical structures. In
conclusion, antibacterial screening data indicated that among all tested thiosemicarbazones
compounds 3c, 3e, 3g, 3h, 3i, 4b and 4d showed excellent antibacterial activity, while
compounds 3g, 3i and 4c exhibited good antibacterial activity against P. aeruginosa when
compared with ampicillin used as a standard substance. Especially, compound 3g which is
bearing the hydroxy and trifluoromethoxy substituents at the para position of phenyl ring
endowed with the most potent antibacterial activity. However, compound 4b which is bearing
morpholino and thiophene groups at the para position of phenyl ring exhibited more potent
antibacterial activity than other morpholino derivatives against tested Gram-positive bacteria.
Other electron donating and electron with-drawing substituents did not significantly increase the
antibacterial activity. Antioxidant screening data showed that all tested thiosemicarbazone
derivatives exhibited excellent scavenging activity on ABTS radical cation. However,
compounds 3e, 3i, 4e, 4g, 4h and 4i showed very good scavenging activity on DPPH radical. All
these results can be useful for future efforts to synthesize and evaluate thiosemicarbazone
derivatives in order to enhance their antibacterial and antioxidant properties.
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ACKNOWLEDGEMENT
The present work was supported by the Scientific Research Projects Governing Unit
Council of Gaziantep University (Grant No. FEF. 08.10), Gaziantep, Turkey for generous
financial support.
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33. Menezes, J. C. J. M. D. S.; Kamat, S. P.; Cavaleiro, J. A. S.; Gaspar, A.; Garrido, J.;
Borges, F. Eur. J. Med. Chem. 2011, 46, 773-777.
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S
NH2
N
N
H
NH2
H
S
H
N
N
N
O
O
N
N
N
H
NH2
N
H2N
S
Triapine
(anticancer)
Thiacetazone
(antitubercular)
Methisazone
(antiviral)
Figure 1. Biologically active thiosemicarbazones
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H
N
H
N
NH2
i
NCS
ii
NH2
S
R
R
R
1, 2
3, 4
3a: R = trifluoromethoxy, R' = furyl
3b: R = trifluoromethoxy, R' = thienyl
3c: R = trifluoromethoxy, R' = 5-nitrothienyl
3d: R = trifluoromethoxy, R' = pyrolyl
iii
3e: R = trifluoromethoxy, R' = 4-fluorophenyl
3f: R = trifluoromethoxy, R' = 4-nitrophenyl
3g: R = trifluoromethoxy, R' = 4-hydroxyphenyl
3h: R = trifluoromethoxy, R' = 4-bis(2-chloroethylamino)phenyl
3i: R = trifluoromethoxy, R' = 4-methoxyphenyl
4a: R = morpholinyl, R' = furyl
H
N
H
N
R'
N
4b: R = morpholinyl, R' = thienyl
4c: R = morpholinyl, R' = 5-nitrothienyl
4d: R = morpholinyl, R' = pyrolyl
S
R
4e: R = morpholinyl, R' = 4-fluorophenyl
4f: R = morpholinyl, R' = 4-nitrophenyl
4g: R = morpholinyl, R' = 4-hydroxyphenyl
4h: R = morpholinyl, R' = 4-bis(2-chloroethylamino)phenyl
4i: R = morpholinyl, R' = 4-methoxyphenyl
3a-i, 4a-i
Scheme 1. Synthetic patways of thiosemicarbazones 3a-i and 4a-i. Reagents and conditions: (i)
CSCl2, NaOH in water, CHCl3, 0°C, 24 h; (ii) NH2NH2.H2O (98%), Et2O, rt, 24 h; (iii)
appropriate aldeyhde in MeCN, reflux.
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Table 1: Drug-likeness properties of the synthesized thiosemicarbazonea.
Compound
Log P
Volume
TPSA
Rotational
bond
H-bond
H-bond
donors
Molecular Weight
acceptors
3.54
4.18
4.29
3.44
4.45
4.25
3.81
5.60
4.34
2.52
3.16
3.25
2.42
3.43
3.22
2.79
4.58
3.32
253.229
262.373
285.707
256.647
276.592
294.995
279.679
378.724
297.207
291.081
300.224
323.559
294.498
314.444
332.847
317.531
416.575
335.059
58.79
45.65
91.48
61.44
45.65
91.47
65.88
48.89
54.88
62.03
48.89
94.71
64.68
48.89
94.71
69.12
52.13
58.12
7
7
5
4
7
5
4
7
5
5
5
6
5
7
6
5
7
6
6
6
2
2
2
3
2
2
3
2
2
2
2
2
3
2
2
3
2
2
329.303
345.371
390.368
328.319
357.332
384.339
355.341
478.355
369.368
330.413
346.481
391.478
329.429
358.442
385.449
356.451
479.465
370.478
3a
3b
3c
3d
3e
3f
8
7
7
8
7
3g
3h
3i
12
8
6
4a
4b
4c
4d
4e
4f
6
8
6
6
8
6
4g
4h
4i
11
7
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aTPSA, topological polar surface area. These parameters were determined with Molinspiration Calculation
software.
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