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3.67–3.70 (q, 1H), 7.21 (br s, 1H), 6.96–7.01 (m, 2H),
7.10–7.16 (m, 4H), 7.39–7.44 (m, 2H). Anal. Calcd for
C21H25NO3: C, 74.31; H, 7.42; N, 4.13. Found: C,
74.68; H, 7.21; N, 4.01.
rat.17 Male Sprague–Dawley rats (150–200 g) were fast-
ed for 16–18 h before use and were divided into parallel
groups (n = 5). The animals were placed temporarily in
restrainer and the resting rectal temperature was record-
ed using a flexible temperature probe connected to Bio-
Pac data acquisition system. The same probe and system
were used for all animals to reduce experimental error.
The animals were returned to their respective cages after
the temperature measurement. Animals were injected
either normal saline or LPS (0.36 mg/kg, Sigma, USA)
intraperitoneally and the rectal temperature was mea-
sured at 0, 5, 6 and 7 h after LPS injection. At 5 h when
the increase in rectal temperature had reached a plateau,
the LPS injected rats were given orally either vehicle (1%
CMC) or test compound (suspended in 1% CMC) to
determine whether the rise in temperature could be
reversed. Percent reversal (Antipyretic activity) was
calculated using the rectal temperature obtained at 7 h
taking this value in the vehicle control group as zero
reversal.
4.3.2. 4-[2-(6-Methoxy-2-naphthyl)propionamido]phenyl
acetate (2C). Yield 90%; mp 212–216 ꢁC; IR (KBr):
3380, 1748, 1668, 1528, 1502, 857 cmꢀ1 1H NMR
;
(CDCl3): d 1.60 (d, 3H), 2.25 (s, 3H), 3.86–3.89 (q, 1H),
3.91 (s, 3H), 8.97 (br s, 1H), 6.95–7.00 (m, 2H), 7.09–
7.14 (m, 1H), 7.38–7.54 (m, 4H), 7.66–7.78 (m, 3H). Anal.
Calcd for C22H21NO4: C, 72.71; H, 5.82; N, 3.85. Found:
C, 72.52; H, 5.62; N, 3.67.
4.3.3. 4-[2-(6-Methoxy-2-naphthyl)acetamido]phenyl ace-
tate (3C). Yield 84%; mp 175–176 ꢁC; IR (KBr): 3305,
1
1750, 1651, 1539, 1506, 839 cmꢀ1; H NMR (DMSO-
d6): d 2.27 (s, 3H), 3.67 (s, 2H), 3.85 (s, 3H), 6.99–7.03
(m, 2H), 7.11–7.15 (m, 1H), 7.33–7.47 (m, 4H), 7.70–
7.77 (m, 3H) 9.06 (br s, 1H). Anal. Calcd for
C21H19NO4: C, 72.19; H, 5.48; N, 4.01. Found: C,
72.49; H, 5.64; N, 3.88.
4.5. In vitro COX inhibition assay
4.3.4. N-(4-Acetoxyphenyl)-5-benzoyl-2,3-dihydro-1H-
pyrrolizine-1-carboxamide (4C). Yield 89%; mp 197–
198 ꢁC; IR (KBr): 3260, 1755, 1661, 1539, 1508,
COX-2 inhibiting activity for the synthesized compound
and parent drugs was determined18 using the colorimetric
ovine cyclooxygenase (COX) assay kit (Cayman Chemi-
cal Company, MI, USA). This assay analyzes the peroxi-
dase activity of the enzymes using N,N,N0,N0-
tetramethylphenylenediamine (TMPD) as the reducing
co-substrate.22 Valdecoxib was used as the positive con-
trol for COX-2 inhibition. The compounds were dissolved
in DMSO and diluted in the assay buffer before use. The
assays were run according to the manufacturer’s
instructions.
1
720 cmꢀ1; H NMR (CDCl3): d 2.28 (s, 3H), 2.80 (m,
2H), 4.08 (m, 1H), 4.53 (m, 2H), 6.17 (br s, 1H), 6.89–
6.90 (d, 1H), 7.04–7.06 (m, 2H), 7.45–7.57 (m, 6H),
7.82–7.85 (m, 2H). Anal. Calcd for C23H20N2O4: C,
71.12; H, 5.19; N, 7.21. Found: C, 71.48; H, 5.41; N, 7.52.
4.3.5. 4-[2-(3-Benzoylphenyl)propionamido]phenyl acetate
(5C). Yield 49%; mp 87–88 ꢁC; IR (KBr): 3357, 1730,
1
1683, 1661, 1538, 1508, 838 cmꢀ1; H NMR (CDCl3):
d 1.62 (d, 3H), 2.27 (s, 3H), 3.72–3.76 (q, 1H), 7.18 (br
s, 1H), 6.98–7.02 (m, 2H), 7.44–7.52 (m, 5H), 7.57–
7.65 (m, 2H), 7.68–7.72 (m, 1H), 7.78–7.82 (m, 3H).
Anal. Calcd for C23H21NO4: C, 73.58; H, 5.64; N,
3.73. Found: C, 73.79; H, 5.38; N, 3.49.
4.6. In vivo carrageenan-induced rat paw edema assay
Anti-inflammatory activity was determined by using car-
rageenan-induced rat paw edema method described by
Winter et al.19 Fasted male Sprague–Dawley rats (150–
200 g) were divided in parallel groups (n = 5) and were
given orally either the vehicle (1% CMC) or test com-
pound as suspension in 1% CMC. The activity was carried
out on equimolar basis to the parent drug. A line was
drawn using permanent marker at the ankle of the left
hind paw to define the arc of the paw to be monitored.
The paw volume (V0h) was measured using a Plethys-
mometer (Ugo-Basile, Italy). The animals were then
injected subplantarly with 50 ll of 1% carrageenan (Sig-
ma, USA) in normal saline solution (i.e., 500 lg carra-
geenan per paw). Three hours after the carrageenan
injection, the paw volume (V3h) was measured, and the in-
crease in paw volume (V3h ꢀ V0h) was calculated. The in-
crease in paw volume was compared with that in the
vehicle control group, and percent inhibition was calcu-
lated taking the values in the control group as 0%
inhibition.
4.3.6. 4-[2-(2-Fluoro-4-biphenyl)propionamido]phenyl ace-
tate (6C). Yield 90%; mp 165–168 ꢁC; IR (KBr): 3357,
1
1732, 1684, 1539, 1509, 764 cmꢀ1; H NMR (CDCl3): d
1.62 (d, 3H), 2.27 (s, 3H), 3.68–3.71 (q, 1H), 7.09 (br s,
1H), 6.98–7.03 (m, 2H), 7.16–7.23 (m, 2H), 7.32–7.49
(m, 6H), 7.52–7.56 (m, 2H). Anal. Calcd for
C23H20FNO3: C, 73.20; H, 5.34; N, 3.71. Found: C,
72.77; H, 5.06; N, 3.95.
4.3.7. 4-[2-(4-Biphenyl)acetamido]phenyl acetate (7C).
Yield 90%; mp 185–188 ꢁC; IR (KBr): 3176, 1751, 1646,
1549, 1501, 746 cmꢀ1; 1H NMR (CDCl3): d 2.26 (s, 3H),
3.77 (s, 2H), 7.15 (br s, 1H), 6.98–7.03 (m, 2H), 733–
7.48 (m, 7H), 7.57–7.63 (m, 4H). Anal. Calcd for
C22H19NO3: C, 76.50; H, 5.54; N, 4.06. Found: C,
76.84; H, 5.81; N, 3.72.
4.4. Antipyretic activity
4.7. Analgesic activity
Antipyretic activity of synthesized compounds (1B–7C)
was determined on rats using lipopolysaccharide (LPS)
(from E. coli) endotoxin for producing pyrexia in
Analgesic activity of the derivatives was evaluated using
the acetic acid writhing model in mice as described
by Koster et al.20 Swiss albino mice (18–25) divided in