Synthesis and anti-inflammatory activity of esters derived from 3-aryl-1,2-dihydro-2-(2-hydroxyethyl)-3H-1,2,4-triazole-3-thiones

Article abstract of DOI:10.1016/S0014-827X(98)00074-3

Some aliphatic and aromatic esters 2a-l were prepared starting from 5-aryl-1,2,4-triazoline-3-thiones bearing a 2-hydroxyethyl chain in position 2. The title compounds were evaluated for antipyretic and anti-inflammatory activities. Nearly all derivatives

Full text of DOI:10.1016/S0014-827X(98)00074-3

Il Farmaco 53 (1998) 590±593
Synthesis and anti-in¯ammatory activity of esters derived from
5-aryl-1,2-dihydro-2-(2-hydroxyethyl)-3H-1,2,4-triazole-3-thiones
a,
a
Silvia Schenone , Olga Bruno , Angelo Ranise , Francesco Bondavalli , Walter Filippelli ,
a
a
b
*
Francesca Rossib, Giuseppe Falconeb
a
Á
Dipartimento di Scienze Farmaceutiche dell'Universita, Viale Benedetto XV 3, I-16132 Genoa, Italy
Á Á
Istituto di Farmacologia e Tossicologia, Facolta di Medicina e Chirurgia, Il Universita degli Studi, Via S. Andrea delle Dame 8, I-80138 Naples, Italy
b
Received 21 July 1998; accepted 20 September 1998
Abstract
Some aliphatic and aromatic esters 2a±l were prepared starting from 5-aryl-1,2,4-triazoline-3-thiones bearing a 2-hydroxyethyl chain in
position 2. The title compounds were evaluated for antipyretic and anti-in¯ammatory activities. Nearly all derivatives and in particular 2f, 2h,
2k exhibited antiphlogistic properties but were lacking in antipyretic activity. q 1998 Elsevier Science S.A. All rights reserved.
Keywords: 5-Aryl-1,2,4-triazoline-3-thiones; Substituted 1,2,4-triazoline-3-thiones; Anti-in¯ammatory agents
1. Introduction
enable us to gather some structure±activity relationships
(SAR).
Several examples of non-steroidal anti-in¯ammatory
drugs (NSAIDs) having a triazole structure have been
recorded in the medicinal chemistry literature. Among
them, 1,2,4-triazolinethione derivatives are of particular
interest and have been studied and patented in recent
years [1±3].
Our continuing interest in the preparation and pharmaco-
logical evaluation of derivatives of simple ®ve-membered
heterocycles with more heteroatoms endowed with anti-
phlogistic properties prompted us to synthesize ®rstly a
series of 1,3,4-thiadiazol-2(3H)-ones [4] and ®nally, at
present, a number of substituted 1,2-dihydro-3H-1,2,4-tria-
zole-3-thiones 2a±l.
2. Chemistry
The synthetic route to the title compounds 2a±l is
outlined in Scheme 1. The most nucleophilic secondary
nitrogen atom of hydrazinoethanol attacks the electrophilic
carbon atom of the heterocumulene function and the
primary amino group dehydrates with the carbonyl group
by catalysis of p-toluenesulphonic acid. This triazoli-
nethione structure 1, and not other possible ones, was
con®rmed by UV and 13C NMR spectral data: two UV
absorption maxima, at l ˆ 255 nm (loge ˆ 4:32) and 2.89
nm (loge ˆ 3:98), were present in accordance with the data
reported by Durant [5] for similar derivatives and a reso-
nance was detected in the 13C NMR spectrum at d 166,
typical of a heterocyclic CyS group (cf. for example 1a).
It was noteworthy that the subsequent acylation reaction
took place on the alcoholic hydroxy group instead of on the
1
NH group, as we could ascertain through IR and H NMR
spectral data of the respective esters 2a±l (Table 1).
These new compounds have as a distinctive feature an
aryl group and an esteri®ed hydroxyalkyl chain. Substitu-
ents on the aryl ring and in the acyl moiety were selected in
order to vary the electronic and lipophilic properties to
3. Pharmacology
Compounds 2a±l were tested in vivo for antipyretic and
anti-in¯ammator activities.
* Corresponding author.
0014-827X/98/$ - see front matter q 1998 Elsevier Science S.A. All rights reserved.
PII S0014-827X(98)00074-3

S. Schenone et al. / Il Farmaco 53 (1998) 590±593
591
Scheme 1.
4. Experimental
2CH2), 7.30±7.70 and 7.80±8.50 (2m, 5H ar), NH and OH
not detectable. 13C NMR (DMSO): d 50.30 (CH2N), 58.34
(CH2O), 125.43 (C ar), 125.94 (2CH ar), 129.41 (2CH ar),
131.02 (CH ar), 148.61 (CyN), 166.45 (CyS). Assignments
of C signals were con®rmed through DEPT experiment.
Anal. C10H11N3OS (C, H, N).
4.1. Chemistry
Melting points were determined with a BuÈchi 530 appa-
ratus. UV spectra were measured in 95% ethanol on a
Perkin±Elmer Lambda 3 spectrophotometer. IR spectra
were measured in KBr with a Perkin±Elmer 398 spectro-
1b: yield 70%; white crystals, m.p. 226±2278C. IR (KBr):
1
3400±2700 (NH and OH) cm21. H NMR (DMSO-d6): d
1
photometer. H NMR spectra were recorded in (CD3)2SO
3.80±4.10 and 4.20±4.50 (2m, 4H, 2CH2), 7.66 and 7.99 (2d,
J ˆ 9:0, 4H ar), OH and NH not detectable. Anal.
C10H10N3OSCl (C, H, N).
1c: yield 80%; white crystals, m.p. 210±2128C. IR (KBr):
3380 and 3100 (NH and OH) cm21. 1H NMR (DMSO-d6): d
3.84 (s, 3H, OCH3), 3.70±4.00 and 4.10±4.40 (2m, 4H,
2CH2), 7.10 and 7.89 (2d, J ˆ 9:0, 4H ar), OH and NH
not detectable. Anal. C11H13N3O2S (C, H, N).
solution on a Hitachi Perkin±Elmer R-600 (60 MHz) instru-
ment, 13C NMR spectra were measured with a Varian
Gemini 200 (50.30 MHz) spectrometer in (CD3)2SO solu-
tion, chemical shifts are reported as d (ppm) relative to TMS
as internal standard; J in Hz. Analyses for C, H, N were
within ^ 0.3% of the theoretical values.
4.1.1. General procedure for 5-aryl-1,2-dihydro-2-
(2-hydroxyethyl)-3H-1,2,4-triazole-3-thiones (1a±c)
2-Hydrazinoethanol (97%) (3.15 g, 40 mmol) were added
slowly to a cooled and stirred solution of the proper aroyl-
isothiocyanate (40 mmol) in anhydrous benzene. The
viscous mixture was then re¯uxed with a Dean & Stark
apparatus for 3 h, in the presence of a catalytical amount
of p-toluenesulphonic acid.
The solvent was removed under reduced pressure and the
residue was dissolved in 1 M sodium hydroxide. The basic
solution, eventually ®ltered from any undissolved residue,
was cooled and acidi®ed with 1 M acetic acid to pH 5.
After 1 h cooling in a refrigerator the precipitate was
®ltered and washed with water to neutrality. The solid
collected was then crystallized from 95% ethanol.
4.1.2. General procedure for esters 2a±l
A solution of the proper acyl chloride (11 mmol) in
toluene (5 ml) was added dropwise with stirring to an ice-
cooled solution of each 1 (10 mmol) in dry pyridine (10 ml).
The resulting mixture was allowed to react at room tempera-
ture overnight. Solvents were then removed under reduced
pressure, the residue was added with water (50 ml), ®ltered
and washed in sequence with 1 M hydrochloric acid and
water. The resulting solids were dried and crystallized
from 70% ethanol. Yields, melting points, IR and NMR
spectral data are recorded in Table 1.
4.2. Pharmacology
The following pharmacological activities were evaluated
by standard procedures: (a) antipyretic activity by yeast-
induced pyrexia in albino rats (5 rats/group) [6]; (b) anti-
in¯ammatory activity, evaluated by carrageenan-induced
paw edema in rats [7] (Table 2). For the most active
1a: yield 90%; white crystals, m.p. 168±1698C. UV
(EtOH): l ˆ 255 nm (loge ˆ 4:32) and 2.89 nm (log e ˆ
3.98). IR (KBr): 3230 (NH and OH) cm21. 1H NMR (CDCl3
1 DMSO-d6): d 3.90±4.20 and 4.30±4.70 (2 near t, 4H,

592
S. Schenone et al. / Il Farmaco 53 (1998) 590±593
Table 1
Yields, physical and spectroscopic data of compounds 2a±l
Comp.
M.p. (8C)
Yield
(%)
IR (cm21
)
1H NMR d (ppm)
Formula
2a
2b
2c
167±168
129±130
148±149
94
95
75
3120 (N±H)
1730 (CyO)
3100 (N±H)
1730 (CyO)
3130 (N±H)
1718 (CyO)
2.04 (s, 3H, CH3), 4.56 (s, 4H, 2CH2), 7.30±7.70 and 7.80±8.10 (2m, 5H ar),
13.47 (br s, 1H, NH, disappears with D2O)
C12H13N3O2S
C14H17N3O2S
C14H15N3O2S
1.06 (d, J ˆ 7:0, 6H, 2CH3), 2.3±2.7 (m, J ˆ 7:0, 1H, CH), 4.48 (s, 4H, 2CH2),
7.40±7.70 and 7.80±8.30 (2m, 5H ar), NH not detectable
0.83 (d, J ˆ 7:0, 4H, 2CH2 cycl.), 1.30±1.80 (qui, J ˆ 7:0, 1H, CH), 4.44 (s,
4H, 2CH2), 7.40±7.70 and 7.80±8.20 (2m, 5H ar), 14.10 (s, 1H, NH, disappears
with D2O)
2d
2e
2f
184±185
162±163
151±152
202±203
174±176
162±163
152±153
78
70
65
80
65
90
51
3230 (N±H)
1680 (CyO)
3120 (N±H)
1733 (CyO)
3100 (N±H)
1723 (CyO)
3120 (N±H)
1720 (CyO)
3220 (N±H)
1670 (CyO)
3100 (N±H)
1725 (CyO)
3100 (N±H)
1725 (CyO)
3.80 (s, 9H, 3OCH3), 4.63 (s, 4H, 2CH2), 7.20±7.40, 7.40±7.70 and 7.80±8.20
(3m, 7H ar), 14.12 (br s, 1H, NH, disappears with D2O)
2.00 (s, 3H, CH3), 4.45 (s, 4H, 2CH2), 7.65 and 8.02 (2d, J ˆ 9:0, 4H ar), 14.18
(br s, 1H, NH, disappears with D2O)
C20H21N3O5S
C12H12N3O2SC
C14H16N3O2SC
C14H14N3O2SCl
C20H20N3O5SCI
C13H15N3O3S
C15H19N3O3S
1.04 (d, J ˆ 7:0, 6H, 2CH3), 2.30±2.60 (m, 1H, CH), 4.45 (s, 4H, 2CH2), 7.63
and 7.96 (2d, J ˆ 9:0, 4H ar), NH not detectable
2g
2h
2i
0.88 (d, J ˆ 7:0, 4H, 2CH2 cycl.), 1.40±1.80 (m, 1H, CH), 4.43 (s, 4H, 2CH2),
7.64 and 8.00 (2d, J ˆ 9:0, 4H ar), NH not detectable
3.80 (br s, 9H, 3OCH3), 4.62 (br s, 4H, 2CH2), 7.20±7.40 (m, 2H ar), 7.59 and
7.91 (2d, J ˆ 9:0, 4H ar), 14.1±14.3 (br s, 1H, NH, disappears with D2O)
1.98 (s, 3H, CH3), 3.83 (s, 3H, OCH3), 4.41 (s, 4H, 2CH2), 7.14 and 7.94 (2d,
J ˆ 9:0, 4H ar), 13.92 (br s, 1H, NH, disappears with D2O)
1.04 (d, J ˆ 7:0, 6H, 2CH3), 2.30±2.75 (m, 1H, CH), 3.85 (s, 3H, OCH3), 4.45
(s, 4H, 2CH2), 7.15 and 7.94 (2d, J ˆ 9:0, 4H ar), 14.00 (br s, 1H, NH,
disappears with D2O)
2j
2k
2l
153±154
223±224
52
48
3100 (N±H)
0.82 (d, J ˆ 7:0, 4H, 2CH2 cycl.), 1.30±1.80 (m, 1H, CH), 3.84 (s, 3H, OCH3),
4.41 (s, 4H, 2CH2), 7.13 and 7.92 (2d, J ˆ 9:0, 4H ar), 13.90 (br s, 1H, NH,
disappears with D2O)
C15H17N3O3S
C21H23N3O6S
1720 (CyO)
3245 (N±H)
1680 (CyO)
3.75 (s, 3H, OCH3), 3.82 (near s, 9H, 3OCH3), 4.60 (br s, 4H, 2CH2), 7.25 (s,
3H ar), 7.06 and 7.83 (2d, J ˆ 9:0, 4H ar), 13.95 (s, 1H, NH, disappears with
D2O)
Table 2
Anti-in¯ammatory activity by carrageenan-induced rat paw edema testa of compounds 2a±l
Compound
Dose (mg/kg p.o.)
Edema volume ml ^ SEb at the following times (h) after treatment (% inhibition activity)
0
1
2
3
4
Control
±
5
1.5 ^ 0.1
1.4 ^ 0.1
1.4 ^ 0.1
1.3 ^ 0.1
1.5 ^ 0.1
1.4 ^ 0.1
1.6 ^ 0.1
1.4 ^ 0.1
1.3 ^ 0.1
1.6 ^ 0.1
1.5 ^ 0.1
1.3 ^ 0.1
1.6 ^ 0.1
1.5 ^ 0.1
1.4 ^ 0.1
1.3 ^ 0.1
1.3 ^ 0.1
1.4 ^ 0.1
1.6 ^ 0.1
1.5 ^ 0.1
1.8 ^ 0.1
1.9 ^ 0.1
2.1 ^ 0.1
2.2 ^ 0.1
Indomethacin
1.6 ^ 0.1 (30)
1.6 ^ 0.1 (30)
1.5 ^ 0.1 (25)
1.8 ^ 0.1 (0)
1.6 ^ 0.1 (30)
1.8 ^ 0.1 (40)
1.6 ^ 0.1 (30)
1.5 ^ 0.1 (25)
1.8 ^ 0.1 (40)
1.7 ^ 0.1 (35)
1.5 ^ 0.1 (25)
1.8 ^ 0.1 (40)
1.7 ^ 0.1 (35)
1.6 ^ 0.1 (30)
1.5 ^ 0.1 (25)
1.5 ^ 0.1 (25)
1.6 ^ 0.1 (30)
1.8 ^ 0.1 (40)
1.7 ^ 0.1 (35)
1.6 ^ 0.1 (38)
1.7 ^ 0.1 (19)
1.6 ^ 0.1 (11)
1.9 ^ 0.1 (0)
1.7 ^ 0.1 (19)
1.9 ^ 0.1 (30)
1.7 ^ 0.1 (19)
1.6 ^ 0.1 (11)
1.8 ^ 0.1 (54)
1.8 ^ 0.1 (23)
1.6 ^ 0.1 (11)
1.9 ^ 0.1 (30)
1.7 ^ 0.1 (50)
1.7 ^ 0.1 (19)
1.6 ^ 0.1 (11)
1.6 ^ 0.1 (11)
1.6 ^ 0.1 (46)
1.8 ^ 0.1 (54)
1.8 ^ 0.1 (23)
1.6 ^ 0.1 (65)
1.8 ^ 0.1 (30)
1.7 ^ 0.1 (25)
1.9 ^ 0.1 (35)
1.8 ^ 0.1 (30)
2.0 ^ 0.1 (37)
1.8 ^ 0.1 (30)
1.6 ^ 0.1 (42)
1.8 ^ 0.1 (70)
1.9 ^ 0.1 (35)
1.7 ^ 0.1 (25)
1.9 ^ 0.1 (55)
1.7 ^ 0.1 (67)
1.7 ^ 0.1 (47)
1.6 ^ 0.1 (42)
1.7 ^ 0.1 (25)
1.7 ^ 0.1 (47)
1.9 ^ 0.1 (55)
1.8 ^ 0.1 (50)
1.6 ^ 0.1 (69)
1.8 ^ 0.1 (39)
1.8 ^ 0.1 (17)
2.0 ^ 0.1 (28)
1.9 ^ 0.1 (23)
2.1 ^ 0.1 (32)
1.9 ^ 0.1 (24)
1.6 ^ 0.1 (50)
1.9 ^ 0.1 (61)
1.9 ^ 0.1 (43)
1.8 ^ 0.1 (17)
2.0 ^ 0.1 (45)
1.8 ^ 0.1 (56)
1.8 ^ 0.1 (39)
1.7 ^ 0.1 (34)
1.7 ^ 0.1 (35)
1.7 ^ 0.1 (51)
1.9 ^ 0.1 (61)
1.9 ^ 0.1 (43)
2a
2b
2c
2d
2e
2f
50
50
50
50
50
25
50
100
50
25
50
100
50
50
25
50
100
50
2g
2h
2i
2j
2k
2l
a Each compound was tested on a group of ®ve albino rats (180±250 g). Compounds were given by gastric probe 30 min before carrageenan (0.1 ml of 1%
solution).
b SE was always smaller than ^ 0.1 ml and so rounded up to this value.

S. Schenone et al. / Il Farmaco 53 (1998) 590±593
593
compounds 2f, 2h, 2k, the respective ED50 values were
determined by administration of three dosages (25, 50,
100 mg/kg).
wake of other triazolinethione analogues, but only at fairly
high dosages.
Acknowledgements
5. Results and conclusions
We thank MURST (Co®nanziamento Nazionale) for
®nancial grant and Mr A. Panaro, C. Rossi and F. Tuberoni
for analytical support.
All the title compounds 2a±l were devoid of antipyretic
activity but were endowed in general with antiphlogistic
properties. In particular 2f showed an ED50 value of 54.64
(44.27±67.44) and 61.09 (48.84±76.42) mg/kg; 2h an ED50
of 52.32 (42.92±63.77) and 73.73 (60.39±90.02) mg/kg; 2k
an ED50 of 71.70 (54.42±94.47) and 50.20 (36.01±69.98)
mg/kg, respectively, after the third and fourth hour from
treatment.
References
[1] G. Mazzone, F. Bonina, R. Arrigo-Reina, G. Blandino, Synthesis of
pharmaceutically signi®cant 1-aryl-4H(R)-thiosemicarbazides, the
corresponding 5-aryl-4H(R)-1,2,4-triazoline-3-thiones and some deri-
vatives, Il Farmaco Ed. Sc. 36 (1981) 181±196.
From the point of view of SAR it was evident that
the acyl group exerted an irregular negligible in¯uence
on the anti-in¯ammatory activity: actually compounds
2a±d, all having a phenyl group in position 5 of the hetero-
cycle, were among the least active compounds. On the
other hand, as regards the aryl group it can be seen that,
with the exception of 2e, in the main the most lipo-
philic electron-attracting p-Cl substituent gave better
results.
Compounds 2f and 2h had a superior activity at the third
hour with a smaller ED50. Another curious feature was that
several derivatives showed an activity comparable or super-
ior to that of indomethacin just after the ®rst hour from
treatment.
[2] T. Somorai, G. Szilagyi, E. Bozo, G. Nagy, 1,2,4-Triazoline-3(2H)-
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Concluding we can say that the prepared compounds may
be considered effective anti-in¯ammatory agents in the