Synthesis, spectroscopic characterization, crystal structure and antifungal activity of thiourea derivatives containing a thiazole moiety

Article abstract of DOI:10.2478/s11532-010-0014-2

Four novel thiourea derivatives containing a thiazole moiety were synthesized and characterized by IR, ¹H and ¹³C NMR, mass spectrometry and elemental analysis. The crystal structure of 1a was determined from single crystal X-ray dif

Full text of DOI:10.2478/s11532-010-0014-2

Cent. Eur. J. Chem. • 8(3) • 2010 • 550–558
DOI: 10.2478/s11532-010-0014-2
Central European Journal of Chemistry
Synthesis, spectroscopic characterization,
crystal structure and antifungal activity of
thiourea derivatives containing a thiazole
moiety
Research Article
Sohail Saeed1,*, Naghmana Rashid1, Peter G. Jones2,
Rizwan Hussain3 and Moazzam Hussain Bhatti1
1Department of Chemistry, Research Complex, Allama Iqbal Open University,
Islamabad, Pakistan
2Institut für Anorganische und Analytische Chemie, Technische Universität
Braunschweig, Postfach 3329, 38023 Braunschweig, Germany
3National Engineering & Scientific Commission, P.O. Box 2801, Islamabad,
Pakistan
Received 31 October 2009; Accepted 18 December 2009
1
Four novel thiourea derivatives containing a thiazole moiety were synthesized and characterized by IR, H and 13C NMR, mass
Abstract:
spectrometry and elemental analysis. The crystal structure of 1a was determined from single crystal X-ray diffraction data. It
crystallizes in monoclinic space group P21/n with unit cell dimensions a = 11.7752(6) Å, b= 3.8677(2) Å, c= 27.4126(13) Å and
= 92.734(5) Å. There is a strong intramolecular hydrogen bond of the type N__H. . .O, with H. . .O distance of 2.5869(19) Å. The
mass fragmentation pattern has also been discussed. The antifungal activity of the synthesized compounds was studied by broth
micro-dilution method and poisoned food technique. The compounds 1b and 1c possessed a broad spectrum of antifungal activity.
Keywords: Thiourea derivatives • Thiazole • X-ray structure determination • Mass fragmentation • Antifungal activity
© Versita Sp. z o.o.
1. Introduction
The biological and synthetic significance, places this
group (thiazole and thiourea) in an important
The development of simple synthetic routes for widely position in medicinal chemistry research. Substituted
used organic compounds from readily available reagents thioureas are an important class of compounds,
is one of the major challenges in organic synthesis. precursors or intermediates towards the synthesis of a
Heterocycles form the basis of
a
variety of variety
of
heterocyclic
systems
such
as
pharmaceutical compounds [1]. The thiazole moiety imidazole-2-thiones [7], 2-imino-1, 3-thiazolines [8],
belongs to an important class of N & S-containing pyrimidine-2-thiones , (benzothiazolyl)-4-quinazolinones
heterocycles and when attached to a thiourea
functional group forms the building block for
[9], N-(substituted phenyl)-N-phenylthioureas which
serve as anion-binding sites in a hydrogen-bonding
pharmaceutical agents. They exhibit a wide spectrum of receptor [10], calix [11], arenes containing thioureas as
pharmaceutical activity, such as bactericidal, fungicidal neutral receptors towards α, α-dicarboxylate anions [12],
[2], analgesic [3], anti-hypertensive [4], and anti-tumor and N-4-substituted-benzyl-N-tert-butylbenzyl thioureas
[5]. Thiouracils are similarly used as anti-inflammatory as vanilloid receptors ligands and antagonists in rate
and virucidal agents [6].
DRG neurons [13].Thioureas are also known to exhibit
* E-mail: sohail262001@yahoo.com
550

S. Saeed, N. Rashid, P. G. Jones, R. Hussain,
M. Hussain Bhatti
a wide range of biological activities including antiviral,
antibacterial, antifungal, anti-tubercular, anti-thyroidal,
herbicidal and insecticidal activities [14] organocatalyst
[15] and as agrochemicals [16,17].
with silica gel GF254 type 60 (25-250 mesh) using an
ethyl acetate-petroleum ether mixture (1:2) as solvent.
As a part of our continuing interest in biologically
active thiourea derivatives, we are reporting a route for 2.3 General Procedure for Synthesis
synthesis of these compounds by using tetrabutyl
ammonium bromide as phase transfer catalyst to
augment the yield of products.
A solution of substituted carbonyl chloride (26 mmol) in
anhydrous acetone (80 mL) and 3% tetrabutyl
ammonium bromide (TBAB) in acetone was added
dropwise to a suspension of ammonium thiocyanate
in acetone (50 mL) and the reaction mixture was
refluxed for 45 minutes. After cooling to room
temperature, a solution of the corresponding
2-aminothiazole (26 mmol) in acetone (25 mL) was
added and the resulting mixture refluxed for 1.5 h. The
reaction mixture was poured into five times its volume
of cold water, whereupon the thiourea precipitated. The
solid product was washed with water and purified
by re-crystallization from an ethanol-dichloromethane
mixture (1:2).
In this
contribution, results of synthesis,
spectroscopic studies, and antifungal activity of thiourea
derivatives bearing the thiazole moiety are presented.
2. Experimental Procedure
2.1 Materials and Chemicals
4-nitrobenzoyl chloride, thiophene-2-carbonyl chloride,
butanoyl chloride, 4-morpholine carbonyl chloride,
ammonium thiocyanate, tetrabutyl ammonium bromide
(TBAB), 2-aminothiazole of analytical grade from Merck 2.3.1 1-(4-nitrobenzoyl)-3-(thiazol-2-yl)thiourea (1a)
were used as received. Solvents; chloroform, acetone,
ethyl acetate, ethanol, methanol, dichloromethane were
obtained from RIEDEL and used without further
purification.
Elemental analysis for C11H8N4O3S2 (MW=308) in wt %
calc. C= 42.85, H= 2.62, N=18.17, S= 20.80, found C=
42.86, H=2.63, N=18.17, S= 20.79. m.pt. 194 - 195 oC,
yield 93 %. IR (KBr pellet) in cm-1: 3352 (free NH),
3208 (assoc. NH), 1686 (C=O), 1615 (C=N stretching),
1592 (aromatic C=C); 1H NMR (400 MHz, DMSO-d6) in
δ (ppm) and J (Hz): 12.80 (1H, s, broad, NH), 11.63 (1H,
s, broad, NH),7.74 (2H, d, J = 8.1 Hz, Ar CH ), 7.66
(2H, d, J = 6.7 Hz, Ar CH), 6.75(1H, d, J = 9.5 Hz, thiaz-
ole CH), 6.55(1H, d, J = 9.5 Hz, thiazole CH); 13C NMR
(300 MHz, DMSO-d6) in δ (ppm): 180.3 (C=S), 168.2
(C=O),164.5 (C=N), 162.4 (C),153.5 (C),140.2 (C),
128.0 (C), 123.4 (C); EI MS, m/z (%): 308 ( M+,12) 262
(6), 166(7), 150(100), 142(25), 123(55), 100(20), 85(9).
2.2 Instrumentation
Synthetic starting material, reagents and solvents were
of analytical grade or of the highest quality commercially
available and were purchased from Aldrich Chemical
Co., Merck Chemical Co. and were dried when
necessary. Melting points were recorded on
Electrothermal IA9000 series digital melting point
apparatus. The proton NMR and 13C spectra were
recorded in DMSO-d6 solvent on Jeol ECS- 400 and
300 MHz spectrophotometer using tetramethylsilane as
an internal reference. The apparent resonance
multiplicity is described as s (singlet), br s (broad
singlet), d (doublet), dd (doublet of doublets), t (triplet),
q (quartet) and m (multiplet). Infrared measurements
were recorded in the range 400-4000 cm-1 on spectrum
2000 by Perkin Elmer. Elemental analysis was carried
out using Perkin Elmer CHNS/O 2400. The mass
spectra were run on a Finnigan TSQ-70 spectrometer
(Finnigan, USA) at 70 eV. X-ray diffraction data was
collected on Oxford Diffraction Xcalibur Nova
diffractometer. Thin layer chromatography (TLC)
analyses were carried out on 5×20 cm plates coated
2.3.2 N-[(1, 3-thiazol-2-ylamino) carbonothioyl]
thiophene-2-carboxamide (1b)
Elemental analysis for C9H7N3OS3 (MW=269) in wt %
calc. C= 40.13, H= 2.60, N=15.60, S=35.71, found C=
o
40.15, H=2.62, N=15.58, S= 35.70. m.pt 179-180 C,
yield 89 %. IR (KBr pellet) in cm-1: 3350 (free NH),
3201 (assoc. NH), 1691 (C=O), 1613 (C=N stretching),
1590 (aromatic C=C); 1H NMR (400 MHz, DMSO-d6) in
δ (ppm) and J (Hz): 12.56 (1H, s, broad, NH), 11.61 (1H,
s, broad, NH), 7.62 (1H, d, J = 7.2 Hz, Thiophene CH),
7.15 (1H, dd, J1 = 7.5 Hz, J2 = 8.2 Hz, Thiophene CH),
7.03 (1H, d, J = 6.7 Hz, Thiophene CH), 6.75(1H, d,
551
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Synthesis, spectroscopic characterization, crystal structure and antifungal
activity of thiourea derivatives containing a thiazole moiety
J = 9.5 Hz, thiazole CH), 6.55(1H, d, J = 9.5 Hz, thiazole
an ethanol-dichloromethane mixture (1:2). A colorless
plate 0.15×0.08×0.005 mm3 was mounted on a glass
fiber in inert oil. Measurements were performed at
100 K on an Oxford Diffraction Xcalibur Nova
CH); 13C NMR (300 MHz, DMSO-d6) in δ (ppm): 179.5
(C=S), 169.1 (C=O),165.0 (C=N), 160.8 (C),141.2 (C),
130.0 (C), 121.4 (C); EI MS, m/z (%): 269( M+,7),
235(10) , 187(8), 142(13), 111(100), 83(4).
diffractometer
with
mirror-focussed
Cu-Kα
radiation to 2 max 152° (99.3% complete to 145°). The
data were corrected for absorption using the multi-scan
method. Of 19592 intensities, 2554 were independent
(Rint 0.051). The structure was refined anisotropically
using SHELXL-97 [32]. NH hydrogens were refined
freely, other H atoms using a riding model. The final
wR2 was 0.081, with a conventional R1 of 0.032, for
2.3.3 N-[(1, 3-thiazol-2-ylamino) carbonothioyl]
morpholine-4-carboxamide (1c)
Elemental analysis for C9H12N4O2S2 (MW=272) in wt %
calc. C=39.70, H= 4.41, N=20.57, S=23.52, found C=
o
39.72, H= 4.45, N=20.56, S= 23.54. m.pt 167-168 C,
yield 90 %. IR (KBr pellet) in cm-1: 3350 (free NH), 3203
(assoc. NH), 1690 (C=O), 1614 (C=N stretching), 1589
189 parameters; S = 1.04; max.
0.27 e Å–3.
1
(aromatic C=C); H NMR (400 MHz, DMSO-d6) in δ
(ppm) and J (Hz) : 12.87 (1H, s, broad, NH), 11.59 (1H,
s, broad, NH), 6.75(1H, d, J = 9.5 Hz, thiazole CH),
6.55(1H, d, J = 9.5 Hz, thiazole CH), 3.7(4H, t, J = 7.6
Hz, morpholine –OCH2), 2.9(4H , t, J = 7.2 Hz,
morpholine –NCH2); 13C NMR (300 MHz, DMSO-d6) in
δ (ppm): 180.3 (C=S), 168.2 (C=O),164.8 (C=N), 162.4
(C),153.5 (C),143.3 (C), 131.2 (C), 123.0 (C); EI MS,
m/z (%): 272( M+,5), 238 (9), 142 (13), 130 (100), 114
(7) , 101(20), 85(23).
2.5 Evaluation of Fungicidal Activity
2.5.1 Broth micro-dilution procedure
Antifungal activity was determined by the broth
micro-dilution procedures and principles of the
Clinical and Laboratory Standards Institute (CLSI)
[33,34]. Minimal inhibitory concentrations for each
compound were investigated against standard
yeast-like fungi, C. albicans (ATCC90028), C. glabrata
(ATCC 32554), C. tropicalis(ATCC 20336). Fungal
colonies of the test organisms were suspended directly
into a small volume of 0.9% saline and further diluted
until turbidity matched the Mc Farland Standard no: 0.5
Petri dishes Sabouraud and Dextrose agar for fungi
were impregnated with these microbial suspensions.
The stock solutions of the synthesized compounds were
prepared in dimethyl sulfoxide (DMSO), which had no
effect on the organisms in the concentrations studied.
The initial concentration was 200 mg mL-1. All of the
dilutions were done with distilled water. The
concentrations of tested compounds were 100, 50, 25,
12.5, 6.25, 3.125 μg mL-1. DMSO was used as negative
control. Nystatin was used as reference drug for
anti-fungal activity. All the inoculated plates were
incubated at 37oC and results were evaluated after
48 h for formation of colonies. The lowest concentration
of the compounds that prevented visible growth
was considered minimal inhibitor concentration (MIC).
2.3.4 N-[ (1, 3 - thiazol -2 - ylamino) carbonothioyl]
butanamide (1d)
Elemental analysis for C8H11N3OS2 (MW=229) in wt %
calc. C=41.92, H= 4.80, N=18.34, S=27.97, found C=
o
41.90, H= 4.83, N=18.31, S= 27.96. m.pt 155- 156 C,
yield 85 %. IR (KBr pellet) in cm-1: 3351 (free NH), 3202
(assoc. NH), 1685 (C=O), 1615 (C=N stretching), 1590
1
(aromatic C=C); H NMR (400 MHz, DMSO-d6) in δ
(ppm) and J (Hz): 12.85 (1H, s, broad, NH), 11.61 (1H,
s, broad, NH), 6.75(1H, d, J = 9.5 Hz, thiazole CH),
6.55(1H, d, J = 9.5 Hz, thiazole CH), 2.48 (2H, t, -CH2, J
= 7.3 Hz), 1.95 (2H, m, -CH2), 0.93 (3H, t, -CH3 ,
J = 7.1 Hz); 13C NMR (300 MHz, DMSO-d6) in δ (ppm):
179.1 (C=S), 168.5 (C=O),164.0 (C=N), 162.4 (C),153.1
(C),140.2 (C), 130.6 (C), 121.4 (C), 25.1, 22.5, 20.0 ; EI
MS, m/z (%): 229( M+,6), 195 (11), 142 (12) , 100 (20)
, 87 (9), 71(100), 44(15).
2.4 X-ray Structure Determination of 1a
Crystal data: C11H8N4O3S2, monoclinic, space group
P21/n, a = 11.7752(6), b= 3.8677(2), c= 27.4126(13) Å,
=92.734(5)°, V = 1247.03 Å3, T = 100K, Z = 4, F (000)
= 632, Dx = 1.642 g cm–3, = 4.0 mm–1. Single crystals
suitable for X-ray diffraction studies were obtained from
552
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S. Saeed, N. Rashid, P. G. Jones, R. Hussain,
M. Hussain Bhatti
Scheme 1.Preparation of compounds 1a-1d
Scheme 2. Mass fragmentation of 1-(4-nitrobenzoyl)-3-(thiazol-2-yl) thiourea (1a)
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Synthesis, spectroscopic characterization, crystal structure and antifungal
activity of thiourea derivatives containing a thiazole moiety
2.5.2 Poisoned food technique
a heterogeneous reaction system is gaining recognition
[21,22]. In an attempt to improve syntheses of the target
In the blotter paper method, surface-sterilized seeds
(with 2.5% bleach-NaOCl for one minute) and untreated
seeds were placed on moistened blotter paper. In this
method, five seeds, sterilized and un-sterilized, were
used and replicated four times. The Petri plates were
incubated at 25±20C under 12 h alternating cycle of
fluorescent light and darkness for a week. Fungi
were identified on the basis of their typical structure
and basic characters as suggested by Barnett [35]
and Melone [36].
substituted
thiourea
derivatives
by reacting
isothiocyanates with nucleophiles, we have found the
use of tetrabutyl ammonium bromide (TBAB) as phase
transfer catalyst (PTC), it can improve the yield of aroyl,
thiophenoyl, morpholinoyl and butanoyl based
isothiocyanates. In this paper, we have carried out
reactions using tetrabutyl ammonium bromide (TBAB)
as phase transfer catalyst to synthesize intermediate
aroyl, thiophenoyl, morpholinoyl and butanoyl thiourea
derivatives containing a thiazole moiety (1a-1d).
The chemical structure and purity of compounds
1
were assessed by using elemental analysis, H NMR,
13C NMR, and FTIR spectroscopy. The 1H NMR data of
the compounds obtained in DMSO are given in the
experimental section and are consistent with the
structural results. The elemental analyses closely
corresponded to calculated values. The analytical and
spectroscopic data are consistent with the proposed
structures [23]. All the compounds were soluble in DMF,
DMSO, ethanol and ethyl acetate. IR (KBr) spectra of
2.6. Statistical Analysis
Data were analyzed statistically by applying ANOVA and
comparing means by using Least Significant Difference
test [38].
The pure cultures of the fungi isolated were maintained
on PDA in tubes, which were stored in the refrigerator at
4oC and used frequently. These were multiplied on 2%
PDA for two-three weeks. The Inoculum was prepared
by taking 1mg culture in 20 mL distilled water. Twenty
seeds of sunflower cultivar, both sterilized and untreated
lots were planted in each pot, replicated five times. All
the target compounds 1a, 1b and 1c were tested for the
fungicidal activity Three seed dressing fungicides (1a-c)
1a-1d had strong N-H absorptions at
about
3353-3208 cm-1 and displayed absorptions at about
1691-1685 cm-1 and 1440 cm-1 which were assigned to
C=O and C=S functionalities respectively. The
medium-strong υ C=O band in the IR spectra of all the
compounds
of series 1a-1d
appeared
at
1691-1686 cm-1, which is lower than that of the ordinary
carbonyl absorption (1730 cm-1); this may be attributed
to the formation of hydrogen bonds. These results agree
with previously reported data [24].
were tested as
isolated through Poisoned Food Technique
growth inhibitors of fungi
[37].
1 mg of each thiourea derivative was dissolved in 20 mL
of Potato Dextrose Agar (PDA) in Petri plates, and one
set of agar plates without addition of fungicide was kept
as control. The plates were incubated at 250C for seven
days, colony of each fungus was measured in cm and
percentage inhibition was calculated as:
Diameter of colony of control- diameter of colony of fungi
% inhibition=
x 100
Diameter of colony of control
3. Results and Discussion
3.1 Chemistry
A thermal ellipsoid drawing of 1-(4-nitrobenzoyl)-3-(thiazol-2-
yl)thiourea (1a) at 50% probability level. The dashed line shows
intramolecular hydrogen bond.
Figure 1.
The synthetic route for the target compounds is outlined
in Scheme 1. Target compounds were synthesized by a
slight modification of our earlier published procedures
[18-20]. The use of phase transfer catalysts to agitate
554
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S. Saeed, N. Rashid, P. G. Jones, R. Hussain,
M. Hussain Bhatti
observed in structures containing the N-benzoyl-N’-
phenylthiourea moiety, as reported in the Cambridge
Structural Database [27]. Disregarding the oxygens
on nitro groups, the molecule consists of two planar
moieties: the C6 ring plus immediate substituents in one
plane and all other atoms in the second plane. Mean
deviations from planarity for both are 0.03 Å, with an
interplanar angle of 34.7° (cf. torsion angle N2-C7-C8-
C13 33.4°). The molecule displays an intramolecular
hydrogen bond N1-H01. . . O1 . The packing is
three-dimensional, but a representative two-dimensional
view along the short axis is given in Fig. 2. One
classical H bond N2-H02. . . S2 and five “weak” H bonds of
the form C-H. . . X (X = O, N, S) are observed. Numerical
details are given in Table 1.
Table 1. Hydrogen bonds [Å and °] for compound 1a
D-H...A
d (D-H)
d (H...A)
d (D...A)
<(DHA)
N (1)-H (01)...O (1)
N (2)-H (02)...S (2) #1
C(10)-H(10)...N(3)#2
C (9)-H (9)...O (1) #2
C (13)-H (13)...S (2) #3
C (12)-H (12)...O (2) #4 0.95
C (5)-H (5)...O (3) #5 0.95
0.89(3)
0.79(3)
0.95
0.95
0.95
1.82(3)
2.65(3)
2.53
2.47
2.87
2.53
2.43
2.5869(19)
3.4208(16)
3.471(2)
3.401(2)
3.7747(18)
3.383(2)
143(2)
167(2)
168.7
167.4
160.5
150.3
141.7
3.228(2)
Symmetry transformations used to generate equivalent atoms:
#1 -x+1,-y+2,-z+1
#2 -x,-y+2,-z+1
#3 -x+1,-y+1,-z+1
#4 -x+1/2,y-1/2,-z+1/2
#5 x+1/2,-y+3/2,z+1/2
Table 2.MIC values (μg mL-1) of the promising thiourea derivatives
against the tested fungi
_______________________________________________________________
Compound C.glabrata
C.albicans
C. tropicalis
3.3 Antifungal Activity
Code
1a
1b
1c
1d
(ATCC32554)
(ATCC 90028)
(ATCC 20336)
100
50
25
100
2
100
50
50
50
1
200
50
50
50
4
To determine the antifungal activity of synthesized
compounds,twomethods,brothmicro-dilutionprocedure
and poisoned food technique were adopted. In the
light of interesting antimicrobial activity , the thiourea
derivatives were screened for antifungal activity against
3 fungal strains: C.glabrata, C.albicans and C. tropicalis
by broth micro-dilution procedure (see Table 2).
All the compounds inhibited the growth yeast with
MIC (minimum inhibitory concentration) ranging
from 25 to 200 μg mL-1. When all the anti-yeast MIC
values are compared, two of four compounds showed
good activity against C. glabrata and other two of four
compounds showed low activity against C. tropicalis.
The investigated compounds antifungal activity values
for our compounds were similar to those reported [28-
30]. The main difference in the thiourea derivatives
reported in this paper is the presence of the thiazole
moiety.
Nystatin
The 1H NMR of the compounds 1a-1d exhibited broad
signals at 12.80-11.59 ppm, which were assigned
to the N-H protons. 13C NMR of compound 1a-1d
showed peaks at about δ 170.2-165.1, 180-179.5 for
C=O (amide) and C=S (thioamide), respectively. Mass
spectrum of compound 1a showed molecular ion peak
at m/z 308. The major fragment at m/z 142 (25%) was
derived from N-McLafferty rearrangement and a base
peak at m/z 150 (100 %) originated from the aroyl cation
(Scheme 2). Mass spectrum of compounds 1b and
1c showed molecular ion peaks at m/z 269 and m/z
272, respectively. The base peak for both compounds
appeared at m/z 111 and 130 (100%), respectively.
Lipophilicity is a factor, which correlates well
with the bioactivity of chemicals. It is a very important
molecular descriptor and the lipophilic behavior of
compounds plays an important role in their biological
activity. The n-octanol/water partition coefficient (log
Pow) is widely used as a general measure of lipophilicity.
Compound with 4-nitrophenyl (1a) has relatively
higher log Pow value of 1.94 ± 0.65 and hence show
more lipophilic character [31]. Its antifungal activity is
lower than all the other promising compounds(1a-d).
The calculated value of partition coefficient (log Pow)
for n-butyl derivative (1d) is 1.29 ± 0.64. Its antifungal
activity is comparatively lower than the compounds (1c)
and (1b) due to its higher partition coefficient (log Pow)
value. The compounds with a morpholine ring (1c) and
3.2 Crystal Structure study
Molecular structure of compound 1a is shown in Fig 1.
The C6-S2 and C7-O1 bonds show a typical double
bond character with bond lengths of 1.6562(18) and
1.229(2) Å, respectively. All of the C-N bonds, C6-N1
= 1.343(2) Å, C6-N2 = 1.396(2) Å, C2-N3 = 1.307(2)
Å, C2-N1= 1.389(2) Å, C4-N3 = 1.373(2) Å, C7-N2 =
1.379(2) Å also indicate a partial double bond character.
The C6-N2 bond due to its vicinity to the carbonyl group
is slightly shorter than to the C2-N1 bond [25,26]. These
bond distances are in good agreement with those
555
558

Synthesis, spectroscopic characterization, crystal structure and antifungal
activity of thiourea derivatives containing a thiazole moiety
Figure 2.Packing diagram of 1a viewed parallel to the y axis. The dashed lines denote hydrogen bonds, thick lines denote N-H---S; thin lines
represent
C-H---X with X = N, O, S). Non-hydrogen bonded H atoms and intramolecular H bonds have been omitted for clarity.
thiophenering(1b), whichhavethelogPow valueof0.76±
0.68 and 1.59 ± 0.65, respectively show higher antifungal
activity than other investigated compounds probably
due to their lower lipophilic character. In poisoned food
technique the prepared thiourea derivatives were tested
against seven isolated fungi namely, A. alternata,
A. flavus, A. niger, Rhizopus spp, Curvularia lunata,
D. tetramera and Penicillium spp. as presented in
Table 3. The results showed that 1b and 1c produced
significant decrease in mycelial growth as compared
to 1a. All the treated fungi showed significant decrease
in fungal colony diameter with respect to control. The
compound 1b gave 79.93% inhibition of Rhizopus spp.
61.73% of A.niger and 58.01% of A.alternata (Fig.3b).
In conclusion, treatment with compounds 1b and
1c showed significant reduction in fungal colonies.
It can be hypothesized that these active molecules
might have entered the fungal mycelium, interacted with
in a short time and paralyzed it. Chemical ingredients
present in these two fungicides may be inhibitory to
germination of fungal propugules.
Fungicidal seed treatments are known to
reduced the
seed-borne mycoflora and thereby
improve seed germination. However, chemical seed
treatment can produce serious problems leading to
toxicity, phytotoxicity, environmental and soil pollution,
bioaccumulation etc. Nevertheless, it is quite economical
and easily applicable.
Table 3. Effect of thiourea derivatives (1a-c) on the % inhibition of fungal colonies (cm) on agar medium at 25oC
Treatment
Control
1b
c
d
e
a
b
f
g
2.675 A
3.125 A
4.375 A
1.675 B
1.975 B
2.375 B
0.56
3.175 A
1.950 B
1.125 C
2.825 A
0.69
2.925 B
1.475 B
0.875 D
2.800 A
0.52
3.550 A
1.475C
1.275 C
3.100 A
0.57
4.400 A
1.975 B
2.025 B
2.800 A
0.72
0.55 D
1.250 C
1.625 BC
0.43
1.500 B
0.825 C
2.050 B
0.45
1c
1a
LSD value
Alternaria alternates (a), A. flavus (b), A. Niger(c), Curvularia lunata (d), D.tetramera (e), Rhizopus spp (f), Penicillium spp (g) P<0.05 values within the same column
show the same letters are not significantly different from each other.
556
559

S. Saeed, N. Rashid, P. G. Jones, R. Hussain,
M. Hussain Bhatti
5. Supplementary crystallographic
data
1a
60
40
% inhibition
20
Crystallographic data for the structure reported in
this article have been deposited with Cambridge
Crystallographic Data Center, CCDC 752674 .Copies of
this information may be obtained free of charge from the
Director, CCDC, 12 Union Road, Cambridge, CBZ IEZ,
UK. Facsimile (44) 01223 336 033, E-mail: deposit@
ccdc.cam.ac.uk or http//www.ccdc.com.ac.uk/deposit.
0
A. alternata
Curvularia lunata
Penicillium spp
A. flavus
A. niger
Dreschlera tetramera Rhizopus spp
1b
80
60
Acknowledgements
% inhibition
40
20
0
The authors are indebted to Gul Akhtar Khan, Manager
(Quality Control), National Engineering & Scientific
Commission, Islamabad for providing the facility
of elemental analyzer. Special thanks to Dr. Abid
Mehmood, Mycologist, Department of Plant Pathology,
Agriculture University of Faisalabad for his help in the
study of antifungal activities and to Mr. Malik Iftikhar
Ahmed, Associate Professor, Department of Statistics
for his support and guidance in statistical analysis.
A. alternata
A. flavus
A. niger
Curvularia lunata
Penicillium spp
Dreschlera tetramera Rhizopus spp
1c
80
60
% inhibition 40
20
0
References
A. alternata
Curvularia lunata
Penicillium spp
A. flavus
A. niger
Dreschlera tetramera Rhizopus spp
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