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A. Frymarkiewicz, K. Walczyn´ski / European Journal of Medicinal Chemistry 44 (2009) 1674–1681
thiazole);
d
¼ 7.21–7.34 (m, 5H); TLC (methylene chlor-
(1 10ꢃ6 mol/L)). Whole jejunum segments (2 cm) were prepared
and mounted between two platinum electrodes (4 mm apart) in
20 mL Krebs buffer, continuously gassed with 95% O2:5% CO2 and
maintained at 37 ꢁC. Contractions were recorded isotonically under
1.0 g tension with Hugo Sachs Hebel–Messvorsatz (Tl-2)/HF-
modem (Hugo Sachs Electronik, Hugstetten, Germany) connected
to a pen recorder. After equilibration for 1 h with washings every
10 min, the muscle segments were stimulated maximally between
15 and 20 V and continuously at a frequency of 0.1 Hz and a dura-
tion of 0.5 ms, with rectangular-wave electrical pulses, delivered by
a Grass Stimulator S-88 (Grass Instruments Co., Quincy, USA). After
ide:methanol:concentrated ammonium hydroxide, 89:10:1)
Rf ¼ 0.36. mptreehydrobromide ¼ 256-258 ꢁC.
Elemental analysis for threehydrobromide C20H33Br3N4S
(M ¼ 601.31).
C (%)
H (%)
5.53
5.51
N (%)
9.32
9.36
Calculated 39.95
Found
39.67
Compound 4c2: C22H34N4S (M ¼ 386); yield 74%; 1H NMR
(CDCl3):
d
¼ 0.89–0.93 (t, 3H, –CH3, J ¼ 7.5 Hz);
d
¼ 1.48–1.53 (m,
30 min of stimulation, 5 min before adding (R)-a-methylhistamine,
2H, –CH2–);
d
¼ 1.78–1.83 (m, 2H, –CH2–);
¼ 2.29–2.34 (m, 2H, –CH2–); ¼ 2.40–2.45 (tm, 2H, –CH2–);
¼ 2.51–2.66 (m, 6H, –CH2–; –CH2–; –CH2–); ¼ 2.76–2.81 (m, 2H,
¼ 3.41–3.47 (m, 4H, –CH2–; –CH2–); ¼ 6.88 (s, 1H,
¼ 7.26–7.30 (m, 2H); TLC (hex-
100:100:2)
Rf ¼ 0.46.
d
¼ 2.26 (s, 3H, –CH3);
pyrilamine (1 ꢂ10ꢃ5 mol/L concentration in organ bath) was
d
d
d
added, and then cumulative concentration response curves (half-
d
log increments) of (R)-a-methylhistamine, H3-agonist, were
–CH2–);
thiazole);
ane:acetone:triethylamine,
mptreehydrobromide ¼ 256–258 ꢁC.
d
d
recorded until no further change in response was found. Five
minutes before adding the tested compounds, the pyrilamine
(1 ꢂ10ꢃ5 mol/L concentration in organ bath) was added, and after
20 min cumulative concentration–response curves (half-log incre-
d
¼ 7.17–7.25 (m, 3H);
d
Elemental analysis for threehydrobromide C22H36Br3N4S
ments) of (R)-a-methylhistamine, H3-agonist, were recorded until
(M ¼ 629.37).
no further change in response was found. Statistical analysis was
carried out with the Students’ t-test. In all test p < 0.05 was
considered statistically significant. The potency of an antagonist is
expressed by its pA2 value, calculated from the Schild [36] regres-
sion analysis where at least three concentrations were used. The
pA2 values were compared with the potency of thioperamide.
C (%)
H (%)
5.93
5.85
N (%)
8.90
8.97
Calculated 41.99
Found
41.68
Compound 4c3: C24H38N4S (M ¼ 414); yield 46%; 1H NMR
(CDCl3):
–CH2–);
d
¼ 0.90–0.97 (t, 3H, –CH3, J ¼ 7.5 Hz); ¼ 1.31–1.39 (m, 2H,
d
d
¼ 1.66–1.68 (m, 4H, –CH2–; –CH2–);
¼ 2.31–2.39 (m, 4H, –CH2–CH2–); ¼ 2.51–2.63 (m, 6H,
–CH2–; CH2–; –CH2–);
¼ 2.78–2.84 (t, 2H, –CH2–, J ¼ 7.5);
¼ 3.42–3.47 (m, 8H, –CH2–CH2–; –CH2–CH2–); ¼ 6.88 (s, 1H,
thiazole);
¼ 7.24–7.29 (m, 2H); TLC (meth-
d
¼ 2.26 (s, 3H,
4.2.1. H1 antagonistic activity for 4b1, 4b2, 4c1 and 4c2 compounds
Selected compounds were tested for H1 antagonistic effects in
vitro, following standard methods, using the guinea pig ileum [36].
Male guinea pigs weighing 300–400 g were sacrificed by a blow
on the head. The ileum was excised and placed in phosphate buffer
at room temperature (pH 7.4) containing (mM) NaCl (136.9); KCl
(2.68); NaHPO4 (7.19). After flushing the intraluminal contents,
segments of about 2 cm long were cut and mounted for isotonic
contractions in water jacketed 20 mL organ baths filled with
oxygenated (O2:CO2 ¼ 95:5, v/v) Krebs buffer containing (mM) NaCl
(117.5); KCl (5.6); MgSO4 (1.18); CaCl2 (2.5); NaH2PO4 (1.28);
NaHCO3 (25); glucose (5.5) and indomethacin (1 ꢂ10ꢃ6 mol/L) at
37 ꢁC under a constant load of 0.5 g. After a 30 min equilibration
period with washings every 10 min, a submaximal priming dose of
–CH3);
d
d
d
d
d
d
¼ 7.15–7.18 (m, 3H);
d
ylene chloride:methanol:concentrated ammonium hydroxide,
89:10:1) Rf ¼ 0.36; mpthreehydrobromide ¼ 275–278 ꢁC.
Elemental analysis for threehydrobromide C24H41Br3N4S
(M ¼ 657.40).
C (%)
H (%)
6.29
6.50
N (%)
8.52
8.51
Calculated 43.85
Found
43.49
4.1.8. The synthesis of 1-(4-n-propyl)piperazine thioamide (9)
To solution of 1-n-propylpiperazine dihydrobromide
histamine (1 mM) was given and washed out (standard washing
a
procedure: 3 changes of buffer during 30 min). After washing out,
the antagonistic activity of given compounds was measured by
recording a concentration response curve (CRC) for histamine in the
presence of the testing compounds (4b1, 4b2, 4c1 and 4c2) which
was added 5 min before histamine. This procedure was repeated
with higher concentrations of the compounds. The antagonism was
of a competitive nature causing a parallel shift of the CRC. The pA2
values were calculated according to Arunlakshana and Schild [36].
The pA2 values were compared with the potency of pyrilamine.
(0.043 mol) in 5.0 mL of water while stirring a solution of potas-
sium thiocyanate (0.17 mol) in 13.0 mL of water was added, and the
reaction mixture was heated at 70 ꢁC for 24.0 h. After cooling, the
solution was alkalized with KOH (pH ¼ 14) and extracted with
CH2Cl2 (5 ꢂ 30 mL). The organic layer was dried over Na2SO4, the
solvent was evaporated and the residue was crystallized twice from
isopropanol.
C8H17N3S (M ¼ 187); yield 43.0%; 1H NMR (CDCl3):
d
¼ 0.85–0.92
¼ 2.21–
¼ 3.73–3.87
(t, 3H, J ¼ 7.5 Hz, –CH3);
d
¼ 1.45–1.54 (m, 2H, –CH2–CH3);
d
2.37 (m, 2H, –CH2–); 2.40–2.53 (m, 4H, –CH2–; –CH2);
d
Acknowledgments
(m, 4H, –CH2–; –CH2); 5.72 (s*, 2H, –NH2); TLC (methylene chlor-
ide:methanol:concentrated ammonium hydroxide, 89:10:1)
Rf ¼ 0.76; mp ¼ 158–160 ꢁC.
This work was supported by the Polish State Committee for
Scientific Research, Grant No. 502-13-410.
4.2. Pharmacology
References
All compounds were tested for H3 antagonistic effects in vitro on
the guinea pig jejunum [32] using standard methods.
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