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SYNTHESIS AND ANTIMICROBIAL
ACTIVITY OF SOME NEW (SULFONAMIDOPHENYL)-AMIDE DERIVATIVES OF N(4-NITROBENZOYL)-PHENYLGLYCINE AND
N-(4-NITROBENZOYL)-PHENYLALANINE
MIHAELA MOISE1, VALERIU SUNEL1, LENUTA PROFIRE2*,
MARCEL POPA3, CATALINA LIONTE 4
1”
Al. I. Cuza” University, Faculty of Chemistry, Department of Organic
Chemistry and Biochemistry, B-dul Carol I 11, Iasi, 700506
2”
Gr. T. Popa” Medicine and Pharmacy University, Faculty of Pharmacy,
Department of Pharmaceutical Chemistry, Universitatii 16, Iasi, 700115
3”
Gh. Asachi” Technical University, Faculty of Chemical Engineering,
Department of Natural and Synthetic Polymers, Bd. Mangeron 71A, Iasi,
700050
4”
Gr. T. Popa” Medicine and Pharmacy University, Faculty of Medicine,
Emergency Clinic Hospital, Universitatii 16, Iasi, 700115
*corresponding author: nprofire@yahoo.com
Abstract
New sulfonamidophenyl-amides of N-(4-nitrobenzoyl)-phenylglycine and N-(4nitrobenzoyl)-phenylalanine have been synthesized by decyclization of 2-(4-nitrophenyl)-4phenyl-2-oxazolin-5-one and 2-(4-nitrophenyl)-4-benzyl-2-oxazolin-5-one with various
sulphonamides. The structure of the new compounds has been confirmed by elemental and
spectral (1H-NMR) analyses. The DL50 values and the antimicrobial activity of new
synthesized sulphonamides have been also studied.
Rezumat
Au fost sintetizate noi sulfonamidofenil amide ale N-(4-nitrobenzoil)fenilglicinei şi N-(4-nitrobenzoil)-fenilalaninei, prin reacţia de decicilizare a 2-(4nitrofenil)-4-fenil-2-oxazolin-5-onei şi 2-(4-nitrofenil)-4-benzil-2-oxazolin-5-onei cu
diferite sulfonamide. Structura noilor compuşi a fost confirmată prin analiză elementală şi
analize spectrale (1H-RMN). Pentru noii compuşi sintetizaţi s-a stabilit valoarea DL50 şi s-a
studiat acţiunea antimicrobiană.




phenylglycine
phenylalanine
sulphonamides
antimicrobial activity
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INTRODUCTION
The progresses made in the field of antibacterial drugs are due both
to the synthesis of this type of substances, and also to the improvement of
the control methodology for the substances that were tested. Among the
substances used in the antimicrobial therapy, the sulphonamides hold an
important place. On the other hand, the toxicity and selectivity of these
agents depends greatly on the possibility to inhibit folic acid, an
indispensable factor in the synthesis of nucleic acids, and for the cellular
multiplication, respectively [1-4]. According to the structural analogy with
the 4-aminobenzoic acid, the sulphonamides enter in reaction instead of it,
producing non-functional analogues of the folic acid [5-8]. Based on this
data, an idea has been launched according to which phenylglycine,
phenylalanine and its 4-nitrobenzoyl acylated derivatives which are
involved in the metabolism of animal organisms, can decrease the toxicity
of these medicines and, at the same time, may become important antagonists
of the folic acid at the particular cellular level that is involved.
MATERIALS AND METHODS
Chemistry
The 2-oxazolin-5-one compounds (I, II) have been decyclized
with sulfamethoxidiazine, sulfaphenazole and sulphamethoxazole by
heating in anhydrous dioxane solution at 115-120°C, for 5-6 hours, thus
obtaining the sulfonamidophenyl-amides (III-VIII) (Figure 1).
General procedure. In a flask of reaction 2-oxazolin-5-one (I, II)
(0.0025 mol) is dissolved in anhydrous dioxane (25 ml) and then a solution
of 4-aminobenzen-sulfonamide-N-substituted (0.0025 mol) in anhydrous
dioxane (5-10 ml) is added. The mixture of reaction is heated at 115-120°C
for 5-6 hours, on thermostated oil bath, time in which the solution is being
homogenized. The solvent is distilled under vacuum. The remaining residue
is treated with 50 ml of cold water when a collared precipitate is formed.
This is washed with warm water to remove the unreacted reagents, filtered
under vacuum and dried under vacuum at 50 – 60°C, for 5-6 hours. The
purification of the compounds has been done through the recrystallization
from a mixture of ethyl alcohol and water, in a ratio of 1:2.
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O
R
CH
C
O
N
+ H2N
SO2
NH
R
R1
HC
C
NO2(4)
SO2
NH
R1
O
C6H4
I,III-V R =
HN
NH
C
C6H4
CO
C6H5; II,VI-VIII R =
CH2
NO2(4)
C6H5;
N
III,VI R1 =
OCH3 ; IV,VII R1 =
; V,VIII R1 =
N
N
N
;
N
CH3
O
C6H5
Figure 1
Synthesis of the sulfonamidophenyl-amides (III-VIII)
Biological tests
The study of toxicity degree was performed using male white mice
from the Wistar species, weighting 20±2g. The substances were dissolved in
Tween 80 and administered intraperitoneally to groups of four mice. The
animals were studies and the mortality after 7 days had been established.
The antimicrobial activity has been studied using the
Staphylococcus aureus and Escherichia coli strains. We applied the
diffusion Kirby-Bauer method, the tests being performed on the Mueller –
Hinton agar, with 18-hour incubation, at 35° C.
RESULTS AND DISCUSSION
The sulphonamides (III-VIII) are crystalline substances, which are
insoluble into water, but soluble in some organic solvents. Every compound
was characterized by molecular formula, melting point and yield (Table I).
The structure that we proposed was confirmed by the elemental analysis
(Table I) and 1H-NMR spectroscopy (Table II). The combustion analysis
was performed on an Elemental Exeter Analytical CE 440 Apparatus. The
1
H-NMR spectra were recorded in DMFA-d6 solutions on Brucker ARX300 spectrometer (1H: 300 MHz).
The results of the toxicity study (Table III) confirm that the use of
N-(4-nitrobenzoyl)-phenylglycine and N-(4-nitrobenzoyl)-phenylalanine as
„carrying” agents for the bioactive sulphanilamide moiety has a significant
influence in maintaining the toxicity at the established standards; all tested
compounds having a small toxicity.
Table I
Physico-chemical characterization of the sulphonamidophenyl amides (III-VIII)
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Table II
H-NMR spectral data (CD3COCD3; ; ppm)
Comp.
, ppm
III 2.05 (d, 1H, CH), 2.83 (s, 3H, CH3), 3.88 (s, 1H, NH); 7.41 (d, 2H, Ar),
7.55-7.63 (t, 1H, Ar), 7.71-7.79 (t, 2H, Ar), 7.89-8.00 (d, 2H, Ar), 8.03-8.05
(d, 2H, Ar), 8.08 (s, 2H, NH), 8.12 (s, 2H, Ar), 8.20-8.24 (d, 2H, Ar), 8.278.30 (d, 2H, Ar).
IV 2.05-2.06 (d, 1H, CH); 3.58 (s, 1H, NH); 6.49-6.51 (d, 1H, Ar); 6.73-6.97 (t,
3H, Ar); 7.41-7.60 (d, 1H, Ar); 7.63-7.68 (d, 2H, Ar); 7.72-7.82 (d, 4H, Ar);
8.00-8.03 (d, 2H, Ar); 8.06-8.09 (d, 2H, Ar); 8.15 (s, 2H, NH); 8.19-8.30 (t,
3H, Ar); 8.35-8.37 (d, 2H, Ar).
V 2.05-2.07 (d, 1H, CH); 2.34 (s, 3H, CH3); 3.77 (s, 1H, NH); 4.19-4.28 (d,
1H, Ar); 6.21-6.26 (d, 2H, Ar); 6.42-6.71 (t, 3H, Ar); 7.99-8.05 (d, 4H, Ar);
8.07 (s, 2H, NH); 8.25-8.30 (d, 2H, Ar); 8.34-8.66 (d, 2H, Ar).
VI 2.04-2.07 (d, 1H, CH); 3.36-3.39 (t, 2H, CH2); 3.85 (s, 1H, NH); 4.01 (s,
3H, CH3); 7.40 (d, 2H, Ar); 7.51-7.53 (t, 1H, Ar); 7.65-7.79 (t, 2H, Ar);
7.97-8.02 (d, 2H, Ar); 8.09 (s, 2H, NH); 8.13 (s, 2H, Ar); 8.29-8.33 (d, 2H,
Ar); 8.38-8.41(d, 2H, Ar).
VII 2.04-2.06 (d, 1H, CH); 3.32-3.40 (d, 2H, CH2); 3.86 (s,1H, NH); 6.67-6.71
(d, 1H, Ar); 7.03-7.10 (d, 2H, Ar); 7.21-7.23 (d, 2H, Ar); 7.27-7.38 (t, 2H,
Ar); 7.43-7.49 (d, 2H, Ar); 7.61-7.68 (t, 3H, Ar); 7.79-7.81 (d, 1H, Ar);
7.83-7.85 (d, 2H, Ar); 7.90-7.93 (d, 2H, Ar); 8.10 (s, 2H, NH); 8.19-8.21 (d,
2H, Ar); 8.29-8.31 (d, 2H, Ar).
VIII 2.29-2.50 (d, 1H, CH); 2.73 (s, 3H, CH3); 3.13-3.21 (t, 2H, CH2); 3.56 (s,
1H, NH); 6.10-6.13 (d, 1H, Ar); 7.18-7.31 (t, 2H, Ar); 7.45-7.49 (d, 2H, Ar);
7.86-7.90 (d, 2H, Ar); 7.96-7.99 (d, 2H, Ar); 8.04 (s, 2H, NH).
1
Table III
The toxicity degree (DL50 values) of the tested sulphonamides (III-VIII)
Compound
DL50 mg/ body kg
Compound
DL50 mg/ body kg
III
5860
VI
6225
IV
6120
VII
6310
V
6354
VIII
6840
The antimicrobial activity of compounds (V-VII) has been studied
using as reference samples the parents sulphonamides – sulfamethoxidiazine, sulfaphenazole and sulphamethoxazole respectively. From data
presented in table IV we noticed that sulphonamides (VI) and (VII) show a
moderate antimicrobial activity in concentrations under 5 mg, while the
reference samples were inactive at the same concentrations. As the
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concentration increases, the biological activity of sulphamides (VI) and
(VII) is comparable to that in the reference samples, recommending them as
potential antimicrobial agents.
CONCLUSIONS
Six new sulphonamides with N-(4-nitrobenzoyl)-phenylglycine and
N-(4-(nitrobenzoyl)-phenylalanine as support have been synthesized. Their
chemical structure has been confirmed by the elemental and spectral (1HNMR) analyses. We studied the toxicity of synthesized
(sulphonamidophenyl)-amides establishing the DL50. We also tested the
antimicrobial activity for three sulphonamides (V-VII), these inhibiting the
growth of gram-positive and gram-negative bacterial strains at
concentrations higher than 1 mg.
Table III
The antimicrobial activity of compounds (V-VII)
Comp.
Diameter of inhibition zone (mm)
Bacterial strain
Staphylococcus aureus
Escherichia coli
S1
VI
S2
VII
S3
V
S4
VI
S2
VII
S3
V
1mg
2mg
5mg
10mg
20mg
18-19
17-18
10-11
15-16
-
18-19
20-21
18-20
20-22
14-15
22-23
22-23
20-22
23-24
13-14
13-14
13-14
17-18
20-22
22-23
15-16
15-16
22-23
22-23
22-23
23-24
14-15
13-15
18-19
17-18
22-23
22-23
15-16
15-16
24-26
25-27
20-21
20-22
16-17
17-18
20-21
20-21
22-24
23-24
16-17
16-17
S1 - sulfamethoxidiazine, S2 – sulfaphenazole, S3 – sulphamethoxazole, S4 - sulfamethoxidiazine
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