New tetrahydro-2H-1,3,5-thiadiazine-2-thione derivatives as potential antimicrobial agents

Article abstract of DOI:10.1002/1521-4184(20009)333:9<281::AID-ARDP281>3.0.CO;2-E

The deacylated chloramphenicol amine D-(-)-threo-2-amino-1-(4-nitrophenyl)-1,3-diol (D-amine, 1a), and its enantiomer, the L-(+)-threo-form (L-amine, 1b), were introduced into a tetrahydro-2H-1,3,5-thiadiazine-2-thione (THTT) skeleton. They are incorporated in three ways (Chart 1, types I-III at N3 (type I), N5 (type II) or both N3 and N5 (type III of the THTT system. These selections were made in order to investigate the effect of combining the structural features of the THTT and the D-amine on the antimicrobial activity, if any.

Full text of DOI:10.1002/1521-4184(20009)333:9<281::AID-ARDP281>3.0.CO;2-E

Full Papers
New Tetrahydro-2H-1,3,5-thiadiazine-2-thione Derivatives as
Potential Antimicrobial Agents
Abdel-Nasser El-Shorbagi
Faculty of Pharmacy, University of Assiut, Assiut-71526, Egypt
Key Words: Tetrahydro-2H-1,3,5-thiadiazine-2-thione; D-(–)-threo-2-amino-l-(4-nitrophenyl)-1,3-diol;
L-(+)-threo-2-amino-1-(4-nitrophenyl)-1,3-diol; chloramphenicol; antimicrobial activity
[27]
units
. It was thought worthwhile to ascertain whether
Summary
combining the THTT structural features with the deacylated
chloramphenicol (D-amine) or its enantiomer (L-amine)
might provide new antimicrobials with physicochemical
properties differing from those of chloramphenicol. Thus, the
D- and L-amines (1a,b) were introduced into the THTT
skeleton in the three possible ways (Chart 1) at N3 (type I),
N5 (type II), or at both N3 and N5 (type III) of the THTT
system. These selections were done to verify the structure-
antimicrobial activity relationship, if any.
The deacylated chloramphenicol amine D-(–)-threo-2-amino-1-
(4-nitrophenyl)-1,3-diol (D-amine, 1a), and its enantiomer, the
L-(+)-threo-form (L-amine, 1b), were introduced into a tetrahy-
dro-2H-1,3,5-thiadiazine-2-thione (THTT) skeleton. They are in-
corporated in three ways (Chart 1, types I-III) at N3 (type I), N5
(type II) or both N3 and N5 (type III) of the THTT system. These
selections weremadein order to investigatethe effect ofcombining
the structural features of the THTT and the D-amine on the
antimicrobial activity, if any.
Results and Discussion
Introduction
Chemistry
It has been noted that therapy with chloramphenicol must
be limited to infections for which the benefits of the drug
Potassium dithiocarbamate derivatives 2a–d were formed
from reacting the appropriate primary amine 1a–d with carb-
outweigh the risks of the potential toxicities and untoward
[28]
[1–3]
on disulfide and KOH
. Addition of slightly more than two
effects
. Also, resistance to the drug, particularly by gram
equivalents of formalin to the dithiocarbamates 2a–d resulted
in the formation of compounds 3a–d (in situ). Each of the
derivatives 3a–d was then added portionwise to the aqueous
negative bacteria through a plasmid producing acetyltrans-
ferase enzyme that inactivates the drug, is a problem of
[4]
increasing clinical importance . Recent reports about chlor-
amphenicol were oriented to studies of its carriers and pro- solution of the appropriate amine 1a–d, in the presence of
[5–7]
drugs
, in addition to the stereoselective preparation
phosphate buffer (pH = 7.8) to form the target THTT deriva-
tives 4a–d, 5a–d, 6a,b, and 7a,b. Structures of the prepared
compounds were verified on the basis of elemental analyses
and spectroscopic methods. IR spectra showed the absorption
bands related to both of the THTT entity and the D- or
L-amines. Thus, the stretching absorptions in the ranges
[8–11]
of the (±)-threo forms of its intermediates
or ana-
[12,13]
logs
.
On the other hand, among the reported tetrahydrothia-
diazine 2-thiones
shown antibacterial and/or antifungal activities
THTT system is characterized by the presence of a strong
electron-withdrawing group (a thiocarbonyl group) at carbon
2. And, according to the finding that a thiocarbonyl group acts
as a powerful electron withdrawing group, the basicity of
the nitrogen of the parent amine is decreased by 14.1 pK
[14–26]
many of these THTT derivatives had
[14–21]
. This
–1
–1
3500–3350 cm (OH), 3250–2980 cm (aromatic and ali-
Scheme 1. In formulae (a, R from D-amine; b, R from L-amine; c, R =
n-C4H9; d, R = CH3CH2).
Chart 1
Arch. Pharm. Pharm. Med. Chem.
© WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2000
0365-6233/00/0909/0281 $17.50 +.50/0

282
El-Shorbagi
–1
–1
phatic C-H), 1615–1585 cm (C=C), 1380–1345 cm
(NO ) besides the stretching of the thiocarbonyl group
Lipophilicity
2
The synthesized derivatives possess increased lipophilicity
[29]
–1
(C=S) at 1160–1145 cm are considered confirmatory for
the structures. The H-NMR spectra of the synthesized de-
relative to chloramphenicol indicated from their estimated
1
[30–33]
R
M
values
, Table 1.
rivatives revealed among their signals those corresponding to
the THTT methylenes of C4 and C6 (δ value) = 4.48–4.56 in
addition to the p-nitrophenyl group of the D- or L-amine
entities at (δ value) = 7.55–8.28 (experimental). The presence
of a multiplet integrating one proton at a δ value of approx.
6.0 in the spectra of the derivatives 4a,b, 5a,b, 6a,b, and 7a,b
was attributed to the methine proton of C2 of propandiol
entity at N3. To elucidate this, 3,5-diisopropyltetrahydro-2H-
1,3,5-tlüadiazine-2-thione (yield 85%, mp 108 °C) was pre-
pared by the same procedure adopted here, but utilizing
isopropylamine instead of 1a–d. This compound revealed
two methine protons of the isopropyls at both N3 and N5.
A good linear relation is observed between the estimated
lipophilicity of the synthesized derivatives expressed by the
values and the logarithms of the partition coefficient
(log P). The latter computed with a routine method known as
calculated log P (C log P) contained in a PC-software pack-
age (MacLog P 2.0, BioByte Corp., CA, USA). A repre-
sentation of the molecular structure where hydrogens are
omitted, or “suppressed” (SMILES notation), is entered into
R
M
the program, which computes log P based on the fragment
[34]
method
. The regression coefficient of the relation in the
equation was r = 0.931 (n = 12). This improvement in lipo-
philicity by these THTT derivatives relative to chlorampheni-
col may render them more capable of penetrating various
[35]
Measured in DMSO-d , it revealed (δ) 1.10 (6H, d, J = 6.5,
6
biomembranes
, and may thus enhance their bioavailabil-
N5-CH(CH ) ), 1.25 (6H, d, J = 7.0, N3-CH(CH ) ), 3.00
ity at the requisite sites of action.
3 2
3 2
(1H, m (septet), methine N5-CH(CH ) ), 4.50 (4H, s, 4&6
methylenes), in addition to the multiplet at 6.05 (1H, septet
3 2
Antimicrobial Activity
methine N3-CH(CH ) ). From this spectrum it was clearly
3 2
The synthesized THTT derivatives were tested by the cup-
[36]
seen that a very large difference in the chemical shifts exists
between the two methine protons at N3 and N5 of the THTT
system. A high deshielding effect has occurred to that at-
tached to the N3.
plate method adopted with some modifications
against
bacteria such asStaphylococcus aureus, Escherichia coli, and
Pseudomonas aeruginosa versus chloramphenicol as refer-
ence. Also, they were tested against fungi such as Candida
Table 1. Physicochemical data of the synthesized THTT derivatives (4a–d, 5a–d, 6a,b, and 7a,b).
—————————————————————————————————————————————————————————
b
Compd.
No.
R
R1
Yield
M.p.
(%)
Formulaa
RM
C log P
°C
—————————————————————————————————————————————————————————
4a
4b
4c
4d
5a
5b
5c
5d
6a
6b
7a
7b
from D-amine
from L-amine
C4H9
from D-amine
from D-amine
from D-amine
from D-amine
from L-amine
from L-amine
from L-amine
from L-amine
C4H9
74
72
60
51
70
75
61
50
64
72
48
45
oil
oil
108
97
C21H24N4O8S2
C21H24N4O8S2
C16H23N3O4S2
C14H19N3O4S2
C21H24N4O8S2
C21H24N4O8S2
C16H23N3O4S2
C14H19N3O4S2
C16H23N3O4S2
C16H23N3O4S2
C14H19N3O4S2
C14H19N3O4S2
0.066
0.063
0.169
0.105
0.060
0.064
0.158
0.100
0.171
0.162
0.112
0.120
1.019
1.019
2.607
1.549
1.019
1.019
2.607
1.549
2.607
2.607
1.549
1.549
C2H5
from D-amine
from L-amine
C4H9
oil
oil
109
96
C2H5
from D-amine
from L-amine
from D-amine
from L-amine
oil
oil
oil
oil
C4H9
C2H5
C2H5
—————————————————————————————————————————————————————————
a Elemental analyses (C, H, N) were satisfactory within ±0.5% of the calculated values.
b RM value of D- and L-amines are –0.081 and of chloramphenicol is 0.042 under the same experimental conditions.
c C log P value for D- and from L-amine are –0.833 and for chloramphenicol is 0.687.
Arch. Pharm. Pharm. Med. Chem. 333, 281–286 (2000)

New Tetrahydro-2H-1,3,5-thiadiazine-2-thiones
283
Table 2. The results of the antimicrobial investigations.
—————————————————————————————————————————————————————————
Compd. No (Conc.)
I
II
III
IV
V
VI
VII
VIII
IX
—————————————————————————————————————————————————————————
4a
4b
4c
4d
5a
5b
5c
5d
6a
6b
7a
7b
(100 µg)
(200 µg)
(100 µg)
(200 µg)
(100 µg)
(200 µg)
(100 µg)
(200 µg)
(100 µg)
(200 µg)
(100 µg)
(200 µg)
(100 µg)
(200 µg)
(100 µg)
(200 µg)
(100 µg)
(200 µg)
(100 µg)
(200 µg)
(100 µg)
(200 µg)
(100 µg)
(200 µg)
+
++
+++
–
++
+++
+
–
–
–
–
–
–
++
–
+
+
+
+
–
+
–
–
–
–
–
–
++
–
+
++
–
+
+
+
+
–
+
–
+
+
+
++
++
+
–
+
+
+
+
++
+
++
+
+++
+
++
–
++
–
–
–
–
++
+
+
+
++
–
++
–
++
–
++
–
–
+
+
+
–
–
++
+
+++
+
+++
+
+
+
+
+
–
+
–
–
–
–
–
–
+
++
–
++
–
+
+
+
+
–
+
–
+
+
+
+
–
+
+
+
+
++
+
++
+
+
++
+
+
–
++
–
–
–
–
+
++
+
+
+
++
–
+++
–
++
–
++
–
–
+
+
+
–
–
++
–
+++
–
+++
+
++
+
+
+
–
–
+
+
+
+
–
+
+
++
++
+++
+
++
+
++
–
++
–
+
++
–
+
–
++
–
+
–
++
+
+++
+
+
+
++
+
++
+
+
–
++
+
+
+
++
+++
–
++
++++
–
+++
+++
–
++
NT
–
++
NT
–
+
++
NT
–
+
NT
–
++
NT
–
Chloramphenicol
D-Amine; la
L-Amine; lb
Trosyd
NT
–
–
–
–
–
–
–
–
–
–
NT
NT
NT
++++
++++
+++
+++
+++
+++
—————————————————————————————————————————————————————————
I = Staphylococcus aureus; II = Escherichia coli; III = Pseudomonas aeruginosa;
IV = Candida albicans; V = Trichophyton rubrun; VI = Penicillium chrysogenum;
VII = Aspergillus flavus; VIII = Trichothecium roseum; IX = Drechslera halodes;
++++ = very active; +++ = active; ++ = moderately active; + = weak activity; NT = not tested.
albicans, Trichophyton rubrun, Penicillium chrysogenum,
In antibacterial testing, it was found that the coupling be-
Aspergillus flavus, Trichothecium roseum, and Drechslera tween the D-amine and the THTT, in general, afforded de-
halodes versus Trosyd® as reference. Serial concentrations rivatives of moderate to good antibacterial activity, as given
of 50, 100, and 200 µg were used for each compound. Data by 4a, 5a, 6a, and 7a at 200 µg. Compound 4a in which the
of the 100 and 200 µg concentrations are recorded in Table 2. D-amine occupies both N3 and N5 of the THTT skeleton
Arch. Pharm. Pharm. Med. Chem. 333, 281–286 (2000)

284
El-Shorbagi
15 min to a stirred solution of the appropriate la–d (10 mmol) in phosphate
buffer (pH 7.8, 20 ml). After stirring for 6 h at room temperature, the reaction
mixture was acidified to pH = 4 (pH paper) with dilute hydrochloric acid
(2N). Methylene chloride (50 ml) was added and the stirring was continued
for further 30 min. The organic phase was separated, and the aqueous phase
was extracted twice with chloroform (2×50 ml). The combined organic
extract was dried over anhydrous MgSO4 and evaporated under reduced
pressure. The crude oily residue was chromatographed (silica gel, methanol-
chloroform 3%). Yields, melting points, and physicochemical data are given
in Table 1.
appeared to be the most active. For the L-amine containing
derivatives, a weak to moderate activity was obtained espe-
cially by 5b and 7b. In this test the starting D- and L-amines
are inactive at the same dose levels. Moreover, none of the
synthesized derivatives could exceed the effect of chloram-
phenicol (200 µg) as reference drug.
In antifungal testing, the THTT derivatives having simple
alkyl groups (e.g. ethyl or butyl) at either N3 or N5 (e.g. 4c,d,
5c,d, 6b, and 7b) showed moderate antiviral activity when
used at 200 µg concentrations. Again, none of the tested
derivatives exceeds the effect of the reference Trosyd. Fur-
thermore, the D- and L-amines are inactive.
3,5-Bis[D-(–)-threo-(1R,2R)-1,3-dihydroxy-l-(4-nitrophenyl)propan-2-yl]-
tetrahydro-2H-1,3,5-thiadiazine-2-thione; 4a
[α]D20 –8.10 (c = 0.11, CHCI,) NMR, (DMSO-d6, δ): 3.42–4.05 (4H, m,
two -CH2OH), 4.10–4.46 (3H, m, two -CH2OH and N5-CH , 4.49 (4H, br.
s, 4&6 methylenes), 5.23–5.3 8 (4H, m, N3 and N5-CH-CH(OH)-), 6.05 (1H,
m, N3-CH-), 7.65 and 8.24 (8H, each 4H, d, two p-nitrophenyl).
Conclusion
An antibacterial activity could be obtained by introducing
the D-amine in either N3 or N5 of the THTT system as found
for compounds 4a, 5a, 6a, and 7a. A strict relationship with
3-[L-(+)-threo-(1S,2R)-1,3-Dihydroxy-l-(4-nitrophenyl)propan-2-yl]-
5-[D-(–)-threo-(1R,2R)-1,3-dihydroxy-l-(4-nitrophenyl)propan-2-yl]-
tetrahydro-2H-1,3,5-thiadiazine-2-thione; 4b
C log P or R could not be obtained, since derivatives as 5a
M
and 7a representing the lowest and the highest calculated
C log P values.
In the case of antifungal activity: The presence of simple
alkyl groups (e.g. butyl or ethyl; as in 4c,d and 5c,d) at N3 of
the THTT system (type II, Chart 1) afforded moderate anti-
fungal activity. These derivatives are having highC log P and
[α]D20 –0.21 (c = 0.14, CHCl3), NMR (DMSO-d6, δ): 3.42–4.05 (4H, m,
two -CH2OH), 4.10–4.46 (3H, m, two -CH2OH and N5-CH), 4.50 (4H, br.s,
4&6 methylenes), 5.23–5.38 (4H, m, N3 and N5-CH-CH(OH)-), 6.07 (1H,
m, N3-CH-), 7.65 and 8.24 (8H, each 4H, d, two p-nitrophenyl).
3-Butyl-5-[D-(–)-threo-(1R,2R)-1,3-dihydroxy-1-(4-nitrophenyl)propan-
2-yl]tetrahydro-2H-1,3,5-thiadiazine-2-thione; 4c
R
M
values. A moderate antifungal activity is also obtained by
6b and 7b and, again both are of high C log P and R values.
M
[α]D20 –4.00 (c = 0.1, CHCl3), NMR (DMSO-d6, δ): 0.91 (3H, t, J = 7.3,
N3-CH2CH2CH2CH3),1.20–1.95 (4H, m, N3-CH2CH2CH2CH3), 3.40–4.00
(4H, m, -CH2OH, N3-CH2CH2CH2CH3), 4.10–4.49 (2H, m, -CH2OH and
N5-CH), 4.52 (4H, br.s, 4&6 methylenes), 5.20–5.32 (2H, m, N5-CH-
CH(OH)-), 7.62 and 8.22 (4H, each 2H, d, p-nitrophenyl).
Finally, combination between THTT and deacylated
chloramphenicol amine (D-amine) or its inactive enantiomer
(L-amine) may be a successful method of derivatization to
give new antimicrobials of different physicochemical prop-
erties.
3-Ethyl-5-[D-(–)-threo-(1R,2R)-1,3-dihydroxy-1-(4-nitrophenyl)propan-
2-yl]-tetrahydro-2H-1,3,5-thiadiazine-2-thione; 4d
Acknowledgment
20
[α]D –4.40 (c = 0.1, CHCl3), NNR (DMSO-d6, δ): 1.29 (3H, t, N3-
Thanks are to Dr. Abdel-Reheem El-Shanawany, Department of Botany,
faculty of science, Al-Azhar University at Assiut, for carrying out the
antimicrobial testing.
CH2CH3), 3.42–3.90 (2H, m, -CH2OH), 4.10–4.46 (4H, m, -CH2OH, N3-
CH2CH3 and N5-CH), 4.54 (4H, s, 4&6 methylenes), 5.20–5.30 (2H, m,
N5-CH-CH(OH)-), 7.60 and 8.25 (4H, each 2H, d, p-nitrophenyl).
Experimental
3-[D-(–)-threo-(1R,2R)-1,3-Dihydroxy-l-(4-nitrophenyl)propan-2-yl]-
5-[L-(+)-threo-(1S,2S)-1,3-dihydroxy-l-(4-nitrophenyl)propan-2-yl]-
tetrahydro-2H-1,3,5-thiadiazine-2-thione; 5a
General
[α]D20 + 0.27 (c = 0.15, CHCl3), NMR (DMSO-d6, δ): 3.42–4.05 (4H, m,
two -CH2OH), 4.10–4.46 (3H, m, two -CH2OH and N5-CH),4.49 (4H, br.s,
4&6 methylenes), 5.23–5.38 (4H, m, N3 and N5-CH-CH(OH)-), 6.05 (1H,
m, N3-CH-), 7.65 and 8.24 (8H, each 4H, d, two p-nitrophenyl).
Precoated silica gel 60 F-254 plates (Merck) were used for thin layer
chromatography; spots were detected by ultraviolet light and/or staining with
iodine vapor. Melting points were determined on an electrothermal melting
point apparatus [Stuart Scientific, England], and were uncorrected. 1H NMR
Spectra were determined on an EM-60 Varian spectrometer in CDCl3 or
DMSO-d6, using TMS as intemal standardand the chemical shifts were given
in δ ppm. IR spectra were recorded (nujol) on a Shimadzu-408 spectro-
photometer. Optical activity measurements were measured by using Atago
Polax-D (Atago Co., Ltd, Japan) digital polarimeter. Elemental analyses (C,
H, N) were performed at the Department of Chemistry, Faculty of Science,
Assiut University.
3,5-Bis[L-(+)-threo-(1S,2S)-1,3-dihydroxy-l-(4-nitrophenyl)propan-
2-yl]tetrahydro-2H-1,3,5-thiadiazine-2-thione; 5b
[α]D20 +8.14 (c = 0.12, CHCl3), NMR, (DMSO-d6, δ): 3.42–4.00 (4H, m,
two -CH2OH), 4.10–4.46 (3H, m, two -CH2OH and N5-CH), 4.52 (4H, br.s,
4&6 methylenes), 5.23–5.38 (4H, m, N3 and N5-CH-CH(OH)-), 6.05 (1H,
m N3-CH-), 7.65 and 8.24 (8H, each 4H, d, two p-nitrophenyl).
General Procedure for Synthesis of 3,5-Disubstituted Tetrahydro-2H-
1,3,5-thiadiazine-2-thione; 4a–d, 5a–d, 6a,b, 7a,b
3-Butyl-5-[L-(+)-threo-(1S,2S)-1,3-dihydroxy-l-(4-nitrophenyl)propan-
Carbon disulfide (60 mmol) was added portionwise to a stirred mixture of
the appropriate primary amine; 1a–d (10 mmol) and potassium hydroxide
(20%, 10 mmol). Stirring was continued for 4 h at ice-bath temperature and
the resulting reaction mixture was then filtered through filter paper. To the
filtrate, which contains the dithiocarbamates 2a–d, formaldehyde solution
(35%, 22 mmol), was added with stirring at room temperature for 2 h. The
resulting solution of the appropriate 3a–d was added portion-wise during
2-yl]tetrahydro-2H-1,3,5-thiadiazine-2-thione; 5c
[α]D20 +3.91 (c = 0.1, CHCl3), NMR, (DMSO-d6, δ):0.9l (3H, t, J = 7.3,
N3-CH2CH2CH2CH3),1.20–1.95 (4H, m, N3-CH2CH2CH2CH3), 3.40–4.00
(4H,m,-CH2OH, N3-CH2CH2CH2CH3), 4.10–4.49 (2H, m, -CH2OH and
N5-CH), 4.52 (4H, br.s, 4&6 methylenes), 5.20–5.32 (2H, m, N5-CH-
CH(OH)-), 7.62 and 8.22 (4H, each 2H, d, p-nitrophenyl).
Arch. Pharm. Pharm. Med. Chem. 333, 281–286 (2000)

New Tetrahydro-2H-1,3,5-thiadiazine-2-thiones
285
3-Ethyl-5-[L-(+)-threo-(1S,2S)-1,3-dihydroxy-l-(4-nitrophenyl)propan-
detected for each compound as the average of three readings, and the
2-yl]tetrahydro-2H-1,3,5-thiadiazine-2-thione; 5d
corresponding RM values were calculated using the following formula
20
[α]D +3.85 (c = 0.1, CHCl3), NMR, (DMSO-d6, δ): 1.29 (3H, t, N3-
RM = log (1/Rf – 1).
CH2CH3), 3.42–3.90 (2H, m, -CH2OH), 4.10–4.46 (4H, m, -CH2OH, N3-
CH2CH3 and N5-CH), 4.54 (4H, s, 4&6 methylenes), 5.20–5.30 (2H, m,
N5-CH-CH(OH)-), 7.60 and 8.25 (4H, each 2H, d, p-nitrophenyl).
Data are given in Table 1.
References
5-Butyl-3-[D-(–)-threo-(1R,2R)-1,3-dihydroxy-1-(4-nitrophenyl)propan-
2-yl]tetrahydro-2H-1,3,5-thiadiazine-2-thione; 6a
[1] A. Kucers, N. Bennett in, The Use of Antibiotics, (4th Ed.), I.B. Lippin-
20
[α]D –3.76 (c = 0. 1, CHCl3), NMR, (CDCl3, δ): 0.90 (3H, t, J = 7.0,
cott Co., Philadelphia 1987, pp. 757–807.
N5-CH2CH2CH2CH3),1.20–1.90 (4H, m, N5-CH2CH2CH2CH3), 3.20 (2H,
m, N5-CH2CH2 CH2CH3), 3.45–3.90 (2H, m, -CH2OH), 4.25 (1H, m,
-CH2OH), 4.56 (4H, br.s, 4&6 methylenes), 5.10–5.35 (2H, m, N3-CH-
CH(OH)-), 6.10 (1H, m, N3-CH-), 7.60 and 8.28 (4H, each 2H, d, p-ni-
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20
[α]D +4.00 (c = 0.12, CHCl3), NMR (CDC13, δ): 0.90 (3H, t, J = 7.0,
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N5-CH2CH2CH2CH3),1.20–1.90 (4H, m, N5-CH2CH2CH2CH3), 3.20 (2H,
m, N5-CH2CH2CH2CH3), 3.45–3.90 (2H, m, -CH2OH), 4.25 (1H, m, -
CH2OH) 4.56 (4H, br.s, 4&6 methylenes), 5.10–5.35 (2H, m, N3-CH-
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5-Ethyl-3-[D-(–)-threo-(1R,2R)-1,3-dihydroxy-l-(4-nitrophenyl)propan-
2-yl]tetrahydro-2H-1,3,5-thiadiazint-2-thione; 7a
20
[10] J. Zemlicka, M.C. Femandez-Moyano, M. Ariatti, G.E. Zurenko, E.
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Joseph, J.P.G. Ballesta, J. Med. Chem. 1993, 36, 1239–1244.
CH2CH3), 3.42–4.00 (4H, m, CH2OH and N5-CH2CH3), 4.30 (1H, m,
-CH2OH), 4.55 (4H, br.s, 4&6 methylenes), 5.20–5.35 (2H, m, N3-CH-
CH(OH)-), 6.10 (1H, m, N3-CH-), 7.60 and 8.25 (4H, each 2H, d, p-ni-
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20
[14] M. Schorr, W. Durckheimer, P. Klatt, G. Lammler, G. Nesemann, E.
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Schrinner, Arzneim.-Forsch. 1969, 19; 1807–1819.
CH2CH3), 3.42–4.00 (4H, m, CH2OH and N5-CH2CH3), 4.30 (1H, m,
-CH2OH), 4.55 (4H, br.s, 4&6 methylenes), 5.20–5.35 (2H, m, N3-CH-
CH(OH)-), 6.10 (1H, m, N3-CH-), 7.60 and 8.25 (4H, each 2H, d, p-ni-
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Biological Investigations
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1246–1249.
The preliminary screening test was performed according to the cup-plate
method adopted with some modifications [36]. Whatman No. 2 filter paper
discs (5 mm) were impregnated with 50, 100, or 200 µg/ml of the test
compounds in ethanol. The discs were placed on the surface of the cold solid
medium in petri dishes, inoculated with the considered organism. The dishes
were incubated at 5 °C for 1 h to permit good diffusion and then transferred
to an incubator at 37 °C for 24 h for bacteria and at 28 °C for 72 h for fungus.
The results of antimicrobial activity of the prepared compounds are given in
Table 2. The results of chloramphenicol, Trosyd, D-amine and L-amine
(200 µg/ml) as references are also included. A compound was mentioned as
biologically active (+++) when providing an inhibition zone of 12–15 mm,
moderately active (++) with an inhibition zone of 9–12 mm, and weakly
active (+) with an inhibition zone 5–9 mm.
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330, 327–332.
Determination of RM Values of the THTT Derivatives
Silica gel TLC plates [20 µ 20 cm] were soaked for 5 h in acetone contain-
ing 3% n-octanol, then left to dry overnight. From the methanolic solution
(1 mg/ml) of each compound, three spots (each of 5 µl) were loaded at 1.5 cm
intervals. The compounds were allowed to develop by ascending technique
in a chromatographic tank under condition of equilibrium using a mobile
phase of aqueous buffer phosphate solution and acetone (9:1) containing 3%
n-octanol. The plates were dried and the developed spots were localized
under UV lamp and/or staining with iodine vapor. The Rf values were
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Resubmitted: March 16, 2000 [FP434]
Arch. Pharm. Pharm. Med. Chem. 333, 281–286 (2000)