104
M. Sönmez et al. / European Journal of Medicinal Chemistry 41 (2006) 101–105
Table 3
MICs* of the compounds LH, Co(II), Cu(II), Cd(II), Ni(II) and Zn(II) complexes against fungi
Compounds
LH
C. albicans ATCC 27541 C. albicans 1481
C. tropicalis 1828
C. krusei 24941
0.64
1.28
0.02
0.02
0.04
0.02
0.04
0.01
0.64
0.04
0.02
0.005
0.02
0.01
0.005
1.28
0.04
0.04
0.04
0.04
0.04
0.01
[
[
[
[
[
CoL
CuL
CdL
2
2
2
(H
]
(H
2
O)
2
2
]·H
2
O
0.02
0.01
2
O)
]
]
0.005
0.005
0.01
NiL
ZnL
2
(H
(H
2
O)
O)
2
]
2
2
2
Fluconazole
0.005
−
1
*
MICs values were determined as mg ml active compounds in medium.
mids, a mechanism resistance to organometallic compounds of
these metals is still unknown [15]. Moreover, several studies
reported that the organometallic compounds of the divalent ca-
tions are more toxic than their metallic forms, particularly
when compared to their own inorganic equivalents [16,17].
Here, we proposed that the reason for this higher antimicrobial
activity might be related to the structure of the Cd(II) complex
rather than the presence of the metal form of cadmium. Also,
the other cause for the effect could be bounded to the damaged
of the membrane permeabilization and the membrane lipid
composition.
methylhydrazine (3.1 ml, 1 mmol) was mixture in room tem-
perature in dry benzene (30 ml) for approximately 60 min.
After the precipitate was filtered off solvent was removed by
evaporation, the oily residue treated with ether and the formed
crude product was recrystallized from acetic acid to give
1
0.122 g (40%); H-NMR (CDCl ): δ = 9.41 (b, H, OH),
3
1
3
δ = 7.8–7.2 (m, 10H, Harom), 3.9 ppm (s, 3H, CH3); C-NMR
(CDCl ): δ = 193.56 (C=O, benzoyl), 159.21 (C=O), 152.34
3
(C ), 148.88 (C ), 138.20, 137.11, 136.15, 131.52, 131.22,
4
5
130.81, 130.46, 130.27, 121.99, 42.56 ppm (N–CH ) [5].
3
In conclusion, we have synthesized and evaluated in vitro
the antimicrobial activity of the new various metal complexes
3.1.2. Synthesis of the complexes
0.61 g (2.00 mmol) of the ligand was dissolved in 30 ml of
chloroform, and a solution of 1.00 mmol of the metal salt [
of
5-benzoyl-4-hydroxy-2-methyl-6-phenyl-2H-pyridazin-3-
one. According to the in vitro results indicated that the new
various metal complexes of pyridazin-3-one had commonly
of greater toxicological significance than the ligand. Especially
we suggested that the Cd(II) and Ni(II) complexes might be a
promising candidate of new antimicrobial agents.
Cu(CH
Zn(CH
NiCl ·6H
3
COO)
COO)
O (0.24 g)] in 15 ml methanol was added dropwise
2
·H
·2H
2
O (0.20 g), Co(CH
3
COO)
2 2
·4H O (0.25 g),
O (0.22 g), CdCl
·2H O (0.22 g) and
3
2
2
2
2
2
2
with continuous stirring. The mixture was stirred further for
1.5–2.5 h at 80 °C. The precipitated solid was then filtered
off, washed with diethyl ether, followed by cold methanol/
chloroform (1:1 ratio) and dried in vacuum desiccators.
3
. Experimental protocols
MeOH, EtOH, CHCl , DMF, n-butanol, toluene, diethy-
3.2. Biological assays
3
lether, n-heptane and were obtained from E. Merck and
Aldrich. 5-Benzoyl-4-hydroxy-2-methyl-6-phenyl-2H-pyrida-
zin-3-one was synthesized according to the literature [5]. The
metal salts Cu(CH COO) ·H O, Co(CH COO) ·4H O,
3.2.1. Compounds
Test compounds were dissolved in DMSO (12.5%) at an
initial concentration of 2.5 mg ml and then were serially di-
luted in culture medium.
−1
3
2
2
3
2
2
Zn(CH COO) ·2H O, CdCl ·2H O and NiCl ·6H O were ob-
3
2
2
2
2
2
2
tained from E. Merck. All solvents were dried and purified
before use. Elemental analyses (C, H, N) were performed by
using a Carlo Erba 1106 elemental analyzer. The IR spectra were
3
.2.2. Cells
Bacterial strains and C. albicans ATCC 27541 were sup-
−1
plied from American Type Culture Collection (ATCC). Other
human pathogenic fungal isolates (C. albicans 1481,
C. tropicalis 1828 and C. krusei 24941) were obtained from
Department of Infectious Diseases, Faculty of Medicine, Yü-
züncü Yıl University, Van, Turkey.
obtained using KBr discs (4000–400) cm on a Bio-Rad-Win-
IR spectrophotometer. The electronic spectra in the 200–900 nm
range were obtained in DMF on a Unicam UV2-100 UV/visible
spectrophotometer. Molar conductance of the ligand and their
transition metal complexes were determined in DMF at room
temperature by using a Jenway model 4070 conductivitymeter.
1
3.2.3. Antibacterial assays
The H-NMR spectra of the some complexes were recorded
The MICs of the chemical compounds assays were carried
out as described by Clause [18] with minor modifications. Am-
picillin trihydrate was used as reference antibacterial agent. So-
lutions of the test compounds and reference drug were dis-
solved in DMSO at a concentration of 2.56 mg ml . The
twofold dilution of the compounds and reference drug were
prepared (1.28, 0.64, 0.32, 0.16, 0.08, 0.04, 0.02, 0.01,
with a Varian XL-200 NMR instrument. All experiments were
followed by TLC using DC Alufolien Kieselgel 60 F 254 Merck
and Camag TLC Lamp (254/366 nm).
−1
3
3
.1. Synthesis
.1.1. Synthesis of the ligand (LH)
−1
The LH was synthesized according to the literature [5]. An
0.005 >) mg ml . Antibacterial activities of the bacterial
equimolar mixture of furandione (0.278 g, 1 mmol) and
strains were carried out in Muller–Hinton broth (Difco) med-