Synthesis and antimicrobial evaluation of some novel 2-aminothiazole derivatives of 4-hydroxy-chromene-2-one

Article abstract of DOI:10.1002/ardp.200700215

Syntheses of 2-aminothiazole derivatives of 4-hydroxy-chromene-2-one 2c-10c are reported in this paper. These compounds 2c-10c were prepared from 3-(2-bromoacetyl)-4-hydroxy-chromene-2-one 1 and corresponding thiourea derivatives 2b-10b using Hantzsch reaction. The structures of all compounds were confirmed by IR and ¹H-NMR spectroscopy and elemental analyses. The molecules 2c-10c were evaluated for in vitro antimicrobial activity against ten bacteria and twelve fungi. All tested compounds exhibited antibacterial and antifungal activity.

Full text of DOI:10.1002/ardp.200700215

Arch. Pharm. Chem. Life Sci. 2008, 341, 491–496
N. Vukovic et al.
491
Full Paper
Synthesis and Antimicrobial Evaluation of Some Novel
2-Aminothiazole Derivatives of 4-Hydroxy-chromene-2-one
Nenad Vukovic, Slobodan Sukdolak, Slavica Solujic, and Tanja Milosevic
Faculty of Science, Department of Chemistry, Laboratory for Biochemistry, University of Kragujevac
Syntheses of 2-aminothiazole derivatives of 4-hydroxy-chromene-2-one 2c–10c are reported in
this paper. These compounds 2c–10c were prepared from 3-(2-bromoacetyl)-4-hydroxy-chro-
mene-2-one 1 and corresponding thiourea derivatives 2b–10b using Hantzsch reaction. The
structures of all compounds were confirmed by IR and 1H-NMR spectroscopy and elemental anal-
yses. The molecules 2c–10c were evaluated for in vitro antimicrobial activity against ten bacteria
and twelve fungi. All tested compounds exhibited antibacterial and antifungal activity.
Keywords: Antibacterial activity / Antifungal activity / Coumarin / Hantzsch reaction / Thiazole derivatives /
Received: October 21, 2007; accepted: March 27, 2008
DOI 10.1002/ardp.200700215
Introduction
The diverse biological activities of natural and synthetic
coumarin derivatives as anticoagulants and antithrom-
botics are well known [1]. Some of the coumarin deriv-
atives are also reported as triplet sensitizers [2], anti-HIV
agents [3], lipid-lowering agents [4], and antioxidants [5].
They also have been found to inhibit lipid peroxidation
and to possess vasorelaxant [6], anti-inflammatory [7],
anticancer [8], antibacterial, and antifungal activity
[9, 10]. Many coumarin derivatives are also known as free
radical scavengers [11].
Thiazole derivatives are reported to show a variety of
biological activities. Depending on the substituents, this
Scheme 1. Synthesis of the target compounds 2c–10c.
heterocycle possesses antihelmintic, antibiotic, and
immunosuppressant activity [12]. Recent research indi-
cates that some of 2-aminothiazoline derivatives are
inhibitors of enzymes such as kinurenine-3-hydroxylase
[13], or possess inhibitors activity against enzyme cyclin-
dependent kinase [14].
at the coumarin ring. In this paper, synthesis and antimi-
crobial activity of a new series of 2-aminothiazole deriv-
atives of 4-hydroxy-chromene-2-one 2c–10c are
described.
As a part of our investigation in coumarin chemistry
and biochemistry, we present an easy and efficient syn-
thetic method for forming thiazole moiety at position-3 Results and discussion
Thiourea derivatives 2b–10b (Table 1) were synthesized
Correspondence: Nenad Vukovic, Faculty of Science, Department of
Chemistry, Laboratory for Biochemistry, University of Kragujevac, P.O.
BOX 60, Kragujevac, Serbia.
E-mail: nvukovic@kg.ac.yu
Fax: +381 34 336034
in moderate yields by reacting ammonium thiocyanate
with suitable amines 2a–10a.
The synthetic procedure of the 2-aminothiazole deriv-
atives of 4-hydroxy-chromene-2-one 2c–10c is shown in
i 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

492
N. Vukovic et al.
Arch. Pharm. Chem. Life Sci. 2008, 341, 491–496
Table 1. IUPAC Names of thiourea derivatives 2b–10b.
Compound
R1
R2
Thiourea derivative
2b
3b*
4b
5b*
6b
7b
8b
9b*
10b*
H
H
H
H
H
Et
H
H
H
C6H3(OH)COOH
p-C6H4NO2
p-C6H4SO3H
m-C6H4CH3
(CH2)4COOH
Et
m-C6H4CH3
m-C6H4NO2
C10H8N
2-Hydroxy-4-thioureido-benzoic acid
(4-Nitro-phenyl)-thiourea
4-Thioureido-benzenesulfonic acid
m-Tolyl-thiourea
5-Thioureido-pentanoic acid
1,1-Diethyl-thiourea
o-Tolyl-thiourea
(3-Nitro-phenyl)-thiourea
1-(Naphthalen-1-yl)thiourea
* Previously prepared thiourea derivatives
Table 2. Nature of R1 and R2 in thiourea derivatives 2b–10b and the reaction products 2c–10c.
Compound
R1
H
R2
Nomenclature
2c
C6H3(OH)COOH
2-Hydroxy-4-[4-(4-hydroxy-2-oxo-2H-chromen-3-yl)thiazol-2-ylamino]ben-
zoic acid
3c
4c
H
H
p-C6H4NO2
p-C6H4SO3H
4-Hydroxy-3-[2-(4-nitro-phenylamino)-thiazol-4-yl]chromen-2-one
4-[4-(4-Hydroxy-2-oxo-2H-chromen-3-yl)thiazol-2-ylamino]benzenesulfonic
acid
5c
6c
7c
8c
9c
H
H
Et
H
H
H
m-C6H4CH3
(CH2)4COOH
Et
o-C6H4CH3
m-C6H4NO2
C10H8N
4-Hydroxy-3-(2-m-tolylamino-thiazol-4-yl)chromen-2-one
5-[4-(4-Hydroxy-2-oxo-2H-chromen-3-yl)thiazol-2-ylamino]pentanoic acid
3-(2-Diethylamino-thiazol-4-yl)-4-hydroxychromen-2-one
4-Hydroxy-3-(2-o-tolylamino-thiazol-4-yl)chromen-2-one
4-Hydroxy-3-[2-(3-nitrophenylamino)thiazol-4-yl]chromen-2-one
4-Hydroxy-3-(2-(naphthalen-1-ylamino)thiazol-4-yl)-2H-chromen-2-one
10c
Scheme 1. The condensation of thiourea derivatives 2b–
marins were active against Pseudomonas glycinea, mainly
10b with 3-(2-bromoacethyl)-chromene-2-one 1 in ethanol compounds 5c and 8c (MICs were 31.25610– 6 g/mL,
by Hantzsch reaction, led to the thiazole derivatives 2c–
10c (Table 2).
respectively). In the case of test bacteria S. aureus, the
compound 9c exhibited inhibitory activity comparative
All spectral data were in accordance with the assumed to the standardized drug Streptomycin. For all other
structures (Table 3). The IR spectra of the compounds 2b, tested bacteria, the standardized drug streptomycin
4b, 6b, and 8b showed NH and NH2 stretching bands in a exhibited a better inhibiting activity. The weakest inhib-
region of 3169–3447 cm– 1 (compound 7b showed iting activity recorded belongs to the compound 2c
stretching bands from NH2 group at 3399 cm– 1). In the which, at the 500610– 6 g/mL concentration inhibits the
1H-NMR spectra, NH and NH2 protons were seen at 9.00–
12.40 ppm as a singlet. The IR spectra of the novel thia-
growth of bacteria E. coli.
Generally speaking, compounds 2c–12c exhibit a bet-
zole derivatives showed NH-stretching bands in a region ter antifungal rather than antibacterial activity. Regard-
of 3412–3436 cm– 1, aromatic =CH stretching bands at ing antifungal activity, all coumarins showed activities
3028–3084 cm– 1, and coumarin C=O stretching bands at against the tested fungi (Table 5) with MIC values
1676–1726 cm– 1. The 1H-NMR spectra of 2c–10c demon- between 31.25610– 6 g/mL and 125610– 6 g/mL. Com-
strated the presence of the characteristic singlet peaks of pounds 9c and 12c inhibited the growth of eight and
the thiazole ring (59-H) proton (7.64–8.10).
nine strains, respectively, out of the twelve tested fungi
All the reported compounds exhibited moderate in- with MICs = 31.25610– 6 g/mL. A solid antifungal activity
vitro activity against the tested bacterial strains (Table 4). is recorded in the case of the compound 5c against the B.
MIC values were in the range from 31.25610– 6 g/mL to cinerea, C. Albicans, and M. mucedo, and in the case of the
500610– 6 g/mL. Compounds 9c proved to be the most compound 7c against the C. albicans and P. variotii, at the
effective, having a MIC value of 31.25610– 6 g/mL against given MIC value of 31.25610– 6 g/mL. The least antifungal
six of ten tested bacteria. Escherichia coli was the least sen- activity at the concentration of 125610– 6 g/mL is
sitive towards the tested compounds. All the tested cou- recorded in the case of the compounds 2c, 3c and 6c.
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Arch. Pharm. Chem. Life Sci. 2008, 341, 491–496
2-Aminothiazole Derivatives of 4-Hydroxy-chromene-2-one
493
Table 3. Characterization of synthesized compounds.
Compound
IR mmax (cm– 1 a)
)
1H-NMR d (ppm)b)
2b
MW.
Yield % (g)
wi (calc)%c)
wi (found) %
m.p. (8C)
C8H8N2O3S
212.22
56.00 (1.19)
45.28 3.80 13.20
45.15 4.01 13.10
76–78
3360, 3295, 3184 (NH, NH2, OH), 6.08 (d, 1H, J5,6 = 8.5 Hz, C-5-H), 6.14 (s, 1H,3-H),
3028 (=CH), 1637 (C=O), 1525(C- 7.62 (d, 1H, J5,6 = 8.5 Hz, 6-H), 9.5 (s, 2H, NH2),
N), 1304 (NH, scissoring), 1141 10.1 (bs, 1H, OH), 11.9 (bs, 1H, NH), 12.5 (bs,
(C=S)
1H, OH from COOH)
4b
MW.
Yield % (g)
wi (calc) %
wi (found) %
m.p. (8C)
C7H8N2O3S2
232.28
53.00 (1.23)
36.20 3.47 12.06
36.25 3.45 12.01
84–87
3461 (OH), 3220 (NH, NH2), 3063 7.19 (d, 2H, J3,2 = J5,6 = 9 Hz, C-3-H, C-5-H), 9.4 (s,
(=CH), 2912, 1631, 1600, 1548
(C-N), 1312 (NH, scissoring),
1171 (S=O), 1124 (C=S)
2H, NH2), 8.03 (d, 2H, J2,3 = J6,5 = 9 Hz, 2-H, 6-H),
11.82 (s, 1H, NH)
6b
MW.
C6H12N2O2S
176.23
3138 (OH, NH, NH2), 2926 (CH2), 1.55-1.6 (m, 4H, C-3-H, C-4-H), 2.2 (t, 2H, J2,3 =
1754 (C=O), 1100 (C=S)
7 Hz, 2-H), 2.65 (t, 2H, J5,4 = 7.1 Hz, 5-H), 9.0 (s,
Yield % (g)
wi (calc) %
wi (found) %
m.p. (8C)
39.00 (0.86)
40.89 6.86 15.90
40.87 6.89 15.93
Oil*
1H, NH), 9.56 (s, 2H, NH2), 11.8 (bs, 1H, OH
from COOH)
7b
MW.
C5H12N2S
132.22
3399 (NH, NH2), 2994 (CH3),
2981 (CH2), 1140 (C=S)
1.0 (t, 6H, CH3, J = 8.5 Hz), 2.65 (q, 4H, CH2,
J = 8.5 Hz), 9.53 (s, 2H, NH2)
Yield % (g)
wi (calc) %
wi (found) %
m.p. (8C)
61.00 (0.81)
45.42 9.15 21.19
45.45 9.20 21.23
Oil*
8b
MW.
C8H10N2S
166.24
3447 (NH), 3284, 3169 (NH2),
2986 (CH3), 1289 (NH,
6.5-6.7 (m, 2H, 4-H, 5-H), 6.8 (d, 1H, J6,5 = 7.5 Hz,
6-H), 9.5 (s, 2H, NH2), 12.4 (s, 1H, NH)
Yield % (g)
wi (calc) %
wi (found) %
m.p. (8C)
44.00 (0.73)
57.80 6.06 16.85
57.75 6.01 16.91
44
scissoring), 1067 (C=S)
2c
MW.
Yield % (g)
wi (calc) %
wi (found) %
m.p. (8C)
C19H12N2O6S
396.37
79.00 (1.10)
57.57 3.05 7.07
56.90 3.01 7.14
282–284
3413 (NH; OH), 3187 (OH),
3028 (=CH2), 1676 (C=O),
1605 (C=N)
6.21 (s, 1H, 399-H), 6.23 (d, 1H, 599-H, J59,699
8.5 Hz), 7.3 (m, 1H, 6-H), 7.4 (dd, 1H, 8-H, J8,7
8.3 Hz, J8,6 = 1.1 Hz), 7.6 (dd, 1H, 5-H, J5,6
7.8 Hz, J5,7 = 1.7 Hz), 7.7 (m, 1H, 7-H), 7.73 (d,
1H, 699-H, J699,599 = 8.5 Hz), 7.83 (s, 1H, 59-H), 10.1
(bs, 299-OH), 12.11 (s, 1H, 29-NH), 12.52 (bs, 1H,
OH from COOH), 13.27 (bs, 1H, 4-OH)
=
=
=
3c
MW.
Yield % (g)
wi (calc) %
wi (found) %
m.p. (8C)
C18H11N3O5S
381.36
82.70 (1.10)
56.69 2.91 11.02
57.05 2.93 10.95
227–230
3414 (OH; NH), 3072 (=CH),
1726 (C=O), 1600 (C=N) , 1608
and 1369 (NO2)
7.3 (m, 1H, 6-H), 7.35 (d, 2H, J399,299 = J5,6 = 8.2 Hz,
399-H, 599-H), 7.4 (dd, 1H, 8-H, J8,7 = 8.3 Hz, J8,6
=
1.1 Hz), 7.6 (dd, 1H, 5-H, J5,6 = 7.8 Hz, J5,7
=
1.7 Hz), 7.7 (m, 1H, 7-H), 8.03 (d, 2H, J2”,3” = J6”,5”
8.2 Hz, 2"-H, 699-H), 8.10 (s, 1H, 59-H), 10.22 (s,
1H, 29-NH), 13.25 (s, 1H, 4-OH)
=
4c
MW.
Yield % (g)
wi (calc) %
wi (found) %
m.p. (8C))
C18H12N2O6S2
416.43
72.40 (1.05)
51.92 2.90 6.73
51.90 2.87 6.75
247–249
3436 (NH; OH), 3180 (OH),
1694 (C=O), 1600 (C=N),
1099 (S=O)
7.0 (d, 2H, 399-H, 599-H, J3”,2” = J5”,6" = 9 Hz), 7.3 (m,
1H, 6-H), 7.4 (dd, 1H, 8-H, J8,7 = 8.3 Hz, J8,6 =
1.1 Hz), 7.6 (dd, 1H, 5-H, J5,6 = 7.8 Hz, J5,7 =
1.7 Hz), 7.7 (m, 1H, 7-H), 7.78 (s, 1H, 59-H), 8.03
(d, 2H, J2”,3" = J6”,5” = 9 Hz, 299-H, 6-H), 10.31 (s, 1H,
S-OH), 10.94 (s, 1H, 29-NH), 13.24 (s, 1H, 4-OH)
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Arch. Pharm. Chem. Life Sci. 2008, 341, 491–496
Table 3. Continued.
Compound
IR mmax (cm– 1 a)
)
1H-NMR d (ppm)b)
5c
MW.
Yield % (g)
wi (calc) %
wi (found) %
m.p. (8C)
C19H14N2O3S
350.39
84.00 (1.03)
65.13 4.03 7.99
5.10 3.99 8.03
270–273
3412 (NH; OH), 3067 (=CH),
2974 and 2938 (CH3), 1681
(C=O), 1607 (C=N)
2.20 (s, 3H, CH3), 6.6 (d, 1H, J6”,5" = 7.5 Hz, 699-H),
7.2 (m, 1H, 599-H), 7.3 (m, 1H, 6-H), 7.4 (dd, 1H, 8-
H, J8,7 = 8.3 Hz, J8,6 = 1.1 Hz), 7.44 (d, 1H, J4”,5" =
8.5 Hz, 4"-H), 7.5 (s, 1H, 299-H), 7.6 (dd, 1H, 5-H,
J5,6 = 7.8 Hz, J5,7 = 1.7 Hz), 7.7 (m, 1H, 7-H), 8.08
(s, 1H, 59-H), 9.60 (s, 1H, 29-NH), 15.30 (s, 1H, 4-
OH)
6c
MW.
Yield % (g)
wi (calc) %
wi (found) %
m.p. (8C)
C17H16N2O5S
360.38
71.43 (0.90)
56.66 4.47 7.77
57.01 4.23 7.58
224–225
3416 (NH; OH), 3114 (OH),
3084 (=CH), 2926 and 2853
(CH2), 1690 (C=O), 1614 (C=N)
1.5-1.6 (m, 4H, 299-H, 399-H), 2.2 (t, 2H, J = 7 Hz),
3.1 (t, 2H, J = 7.1 Hz, 199-H), 7.4 (dd, 1H, 8-H, J8,7
8.3 Hz, J8,6 = 1.1 Hz), 7.3 (m, 1H, 6-H), 7.6 (dd,
1H, 5-H, J5,6=7.8 Hz, J5,7 = 1.7 Hz), 7.7 (m, 1H, 7-
H), 7.9 (s, 1H, 5'-H), 8.87 (s, 1H, 2'-NH), 9.26 (s,
1H, 599'-OH), 14.98 (s, 1H, 4-OH)
=
7c
MW.
Yield % (g)
wi (calc) %
wi (found) %
m.p. (8C)
C16H16N2O3S
316.37
63.64 (0.70)
60.74 5.10 8.85
60.70 5.15 8.82
245–247
3413 (NH; OH), 3067 (=CH),
2954 (CH3, CH2), 1681 (C=O),
1603 (C=N)
1.04 (t, 6H, 299-H, J = 8.5 Hz), 3.11 (q, 4H, J =
8.5 Hz, 199-H), 7.3 (m, 1H, 6-H), 7.4 (dd, 1H, 8-H,
J8,7 = 8.3 Hz, J8,6 = 1.1 Hz), 7.6 (dd, 1H, 5-H, J5,6 =
7.8 Hz, J5,7 = 1.7 Hz), 7.64 (s, 1H, 59-H), 7.7 (m,
1H, 7-H), 14.89 (s, 1H, 4-OH)
8c
MW.
Yield % (g)
wi (calc) %
wi (found) %
m. p. (8C)
C19H14N2O3S
350.39
54.63 (0.67)
65.13 4.03 7.99
65.09 3.97 8.05
236–238
3414 (NH), 3301 (OH), 3040
(=CH), 2982 (CH3), 1690 (C=O),
1605 (C=N)
2.10 (s, 3H, CH3), 6.4 (d, 1H, J3”,4" = 8 Hz, 3"-H),
6.5 (m, 1H, 5"-H), 6.8 (d, 1H, J6,5 = 7.5 Hz), 6.83
(m, 1H, 4"-H), 7.3 (m, 1H, 6-H), 7.4 (dd, 1H, 8-H,
J8,7 = 8.3 Hz, J8,6 = 1.1 Hz), 7.6 (dd, 1H, 5-H, J5,6
=
7.8 Hz, J5,7 = 1.7 Hz), 7.7 (m, 1H, 7-H), 7.85 (s,
1H, 5'-H), 9.20 (s, 1H, 2'-NH), 14.80 (s, 1H, 4-OH)
9c
MW.
Yield % (g)
wi (calc)%
wi (found)%
m.p.. (8C)
C18H11N3O5S
381.36
67.47 (0.90)
56.69 2.91 11.02
57.07 2.85 10.98
> 300
3415 (NH), 3279 (OH), 3083
(=CH), 1675 (C=O), 1615 and
1352 (NO2)
6.91 (d, 1H, J4”,5" = 8.5 Hz, 499-H), 7.2 (m, 1H, 599-
H), 7.3 (m, 1H, 6-H), 7.4 (dd, 1H, 8-H, J8,7 =
8.3 Hz, J8,6 = 1.1 Hz), 7.43 (s, 1H, 299-H), 7.5 (d,
1H, J6”,5" = 8 Hz, 699-H), 7.6 (dd, 1H, 5-H, J5,6
=
7.8 Hz, J5,7 = 1.7 Hz), 7.7 (m, 1H, 7-H), 7.91 (s,
1H, 59-H), 8.74 (s, 1H, 29-NH), 14.15 (s, 1H, 4-OH)
10c
MW.
C22H14N2O3S
386.42
3413 (NH), 3287 (OH), 3054
(=CH), 1693 (C=O), 1607 (C=N)
6.5 (d, 1H, J2”,3” = 8.2 Hz, 299-H), 7.15 (m, 2H, 399-H,
499-H), 7.3 (m, 1H, 6-H), 7.4 (dd, 1H, 8-H, J8,7 =
Yield % (g)
wi (calc) %
wi (found) %
m.p. (8C)
82.81 (1.12)
68.38 3.65 7.25
68.29 3.72 7.29
278–280
8.3 Hz, J8,6 = 1.1 Hz), 7.45-7.52 (m, 2H, 699-H, 799-
H), 7.56 (m, 2H, 599-H, 699-H), 7.6 (dd, 1H, 5-H, J5,6
= 7.8 Hz, J5,7=1.7 Hz), 7.7 (m, 1H, 7-H), 7.87 (s,
1H, 59-H), 8.57 (s, 1H, 29-NH), 15.54 (s, 1H, 4-OH)
a)
IR spectra were recordered using KBr Disc. For compound 6b and 7b, IR spectra were recorded by liquid film technique.
1H-NMR spectra were recordered using DMSO-d6 as solvent and TMS as internal standard.
Estimated values for m.p. are uncorrected (wi C% H% N%).
b)
c)
* Oil-obtained compounds 6b and 7b are oils at room temperature.
bon, hydrogen, and nitrogen was carried out with a Carlo Erba
1106 microanalyser (Carlo Erba, Milan, Italy). The IR spectra
were run on a Perkin-Elmer Grating Spectrophotometers Model
137 and Model 337, m in cm– 1 (Perkin Elmer, Beaconsfield, UK).
The NMR spectra were recorded on a Varian Gemini 200 spec-
trometer (1H at 200 MHz; Varian Inc., Palo Alto, CA, USA), in sol-
vent DMSO-d6, using TMS (SiMe4) as the internal standard. Chem-
ical shifts are given in d ppm, abbreviations: s-singlet, d-doublet,
t-triplet, q-quartet, ABq-AB quartet, m-multiplet. The reactions
were monitored by thin-layer chromatography (TLC) using Kie-
selgel G according nach Stahl. 3-(2-bromo-acetyl)-4-hydroxy-chro-
mene-2-one 1 as starting compound for Hantzsch reaction with
Other compounds exhibited similar antifungal activity
against tested fungi.
The authors have declared no conflict of interest.
Experimental
Chemistry
Melting points were recorded on a Kofler-hot stage apparatus (C.
Reichert, Vienna, Austria) and uncorrected. Microanalysis of car-
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Arch. Pharm. Chem. Life Sci. 2008, 341, 491–496
2-Aminothiazole Derivatives of 4-Hydroxy-chromene-2-one
495
Table 4. Antibacterial activity of tested coumarin derivatives.
MIC values of tested compounds (10– 6 g/mL)
6c 7c 8c 9c 10c
Bacteria
2c
3c
4c
5c
11
12
Sa)
Gram-positive
Bacillus mycoides
Bacillus subtilis
Staphylococcus aureus
62.5 125
62.5 125
62.5
62.5
62.5
62.5
62.5
62.5 250
62.5
62.5
62.5
62.5
250
62.5
62.5
250
31.25 62.5
31.25 62.5
31.25 125
62.5
62.5
125
62.5
62.5
62.5 31.25
7.81
7.81
125
125
Gram-negative
Agrobacterium tumefaciens
Enterobacter cloaceae
Erwinia carotovora
Escherichia coli
Klebsiella pneumoniae
Pseudomonas fluorescens
Pseudomonas glycinea
62.5 125
62.5 125
62.5 125
62.5
62.5
62.5
62.5
62.5
62.5
125
62.5
62.5
62.5
62.5
125
62.5
62.5 250
31.25 62.5
62.5
62.5
62.5
62.5
62.5
7.81
1.95
7.81
31.25
1.95
7.81
7.81
62.5
62.5
62.5
62.5 125
62.5 250
31.25 62.5
62.5 125
31.25 62.5
500
62.5 125
62.5 125
62.5
62.5 62.5
125
250
62.5
31.25 125
125
125
62.5
62.5
62.5
62.5
62.5
62.5
62.5
62.5
62.5
62.5
62.5
31.25 62.5
31.25 62.5
62.5
62.5
62.5 62.5
31.25 62.5
a)
S = streptomycin
Table 5. Antifungal activity of tested coumarin derivatives.
MIC values of tested compounds (10– 6 g/mL)
Fungi
2c
3c
4c
5c
6c
7c
8c
9c
10c
11
12
Ka)
Ampelomyces quisquialis
Aspergillus flavus
Aspergillus fumigatus
Botrytis cinerea
Candida albicans
Fusarium oxysporum
Fusarium solani
125
62.5
62.5
62.5
62.5
125
125
125
62.5 125
125
62.5
125
62.5
62.5
62.5
62.5
31.25
31.25
62.5
62.5
125
125
125
62.5
62.5
62.5
125
31.25 62.5
62.5 31.25
3.9
3.9
3.9
1.95
1.95
3.9
62.5 62.5
62.5 62.5
62.5 62.5
62.5 62.5
62.5 62.5
62.5 62.5
62.5 62.5
62.5 62.5
62.5
62.5
62.5
125
125
62.5
62.5
62.5 62.5
62.5 31.25 125
62.5 62.5
62.5 62.5
62.5 31.25
62.5 31.25
62.5 31.25
62.5 62.5
31.25 62.5
62.5 31.25 62.5
62.5 62.5 62.5
125
125
62.5
62.5
62.5
3.9
Mucor mucedo
31.25 125
62.5
62.5 31.25 62.5
62.5 31.25 62.5
62.5 31.25 62.5
62.5 31.25 62.5
62.5 31.25 62.5
62.5 31.25 31.25
Paecilomyces variotii
Penicillium purpurescens
Penicillium verrucosum
Trichoderma harsianum
62.5
62.5
62.5
62.5
62.5 31.25
125
62.5 62.5
125
62.5 31.25
62.5 31.25
62.5 31.25
62.5 31.25
1.95
3.9
3.9
62.5 62.5
62.5 62.5
62.5
62.5 125
62.5
62.5
7.8
a)
K = ketoconazole
different thiourea derivatives has been prepared as described
previously [15].
2b–10b were added. The mixture was refluxed for 30–45 min
(Scheme 1.). After cooling, the precipitate was collected and the
final crystalline product was recrystallized from 96% EtOH.
All substituted 2-aminothiazole derivatives were obtained as
pure samples for reputed antimicrobial activity establishment.
General procedure for preparations of the thiourea
derivatives 2b–10b from amines
Ammonium thiocyanate (0.012 mol, 1.00 g) and appropriate
amine were heated in H2O (40 mL) at 80–908C for 3–4 h; then,
the water was removed in vacuo. The residue was treated with
ethyl acetate. From the ethyl acetate solution, insoluble ammo-
nium chloride was removed by filtration under reduced pres-
sure. After ethyl acetate was removed, the corresponding thio-
urea derivatives 2b–10b were obtained. Methanol was used for
recrystallization and the crystals were dried in vacuo. Thiourea
derivatives 6b and 7b were obtained as oil. The purification of all
compounds was performed by column chromatography silica
gel 60 (230–400 mesh ASTM) using benzene / methanol (9 : 1).
Microbiology
Determination of the minimal inhibitory concentrations (MIC)
of the compounds by microbroth dilution method [15, 16].
Sample preparation
The compounds were dissolved in 5% DMSO (1000 lg/mL) for
both the antibacterial and antifungal assays. Further dilutions
of the compounds and standard drugs in the test medium were
prepared at the concentrations of 15.62, 31.25, 62.5, 125, 250,
and 500610– 6 g/mL with Mueller–Hinton broth and Sabouraud
dextrose broth. The minimum inhibitory concentrations (MIC)
were determined using the twofold serial-dilution technique. A
control test was also performed containing inoculated broth
supplemented with 5% DMSO only at the same dilutions used in
General procedure for the synthesis of compounds
2c–10c
To a solution of 3-(2-bromoacetyl)-4-hydroxy-chromene-2-one 1
(1 g, 3.5 mmol) in absolute ethanol (60 mL), thiourea derivatives
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496
N. Vukovic et al.
Arch. Pharm. Chem. Life Sci. 2008, 341, 491–496
our experiments. As control drugs, streptomycin and ketocona-
zole were chosen.
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Test bacteria which were used in this experiment are a) Gram-
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B2), Staphilococcus aureus (ATCC 25923); b) Gram-negative bacte-
ria: Agrobacterium tumefaciens (FAB 231), Enterobacter cloaceae
(FAB 22), Erwinia carotovora (FAB 73), Escerichia coli (ATCC 25922),
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fumigatus (DBFS 310), Botrytis cinerea (DBFS 133), Candida albicans
(ATCC 10259), Fusarium oxysporum (DBFS 292), Fusarium solani
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Assay for in-vitro antimicrobial activity
Bacteria were cultured for 24 h at 378C in Mueller–Hinton broth
(Difco). Suspensions of fungal spores were prepared from two-
day old cultures which were growth on SDA plates at 308C. The
final inoculum size was 106 CFU/mL (according to 0.5 Mc Farland
standard; turbidimetric method was applied) for the antibacte-
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technique was applied. A set of tubes containing only inoculated
broth was kept as a control. Bacterial and fungal plates were
made in duplicate and incubated at 378C within 24 h for bacte-
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screened under similar conditions. MIC is defined as the lowest
concentration of the compound that inhibited visible growth.
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www.archpharm.com