72 A.A. Bekhit et al.
Table 2. Spectral data of compounds 2a–h, 4a–e and 5.
Compound IR (KBr, cm−1)
1H NMR (DMSO-d6)
2a
3522 (OH), 3207 (NH), 1668 (C=O), 6.91 (d, 2H, J=8.80 Hz, phenyl–C2,6 H), 7.75 (d, 2H, J=8.80 Hz, phenyl–C3,5H), 7.95
1652 (C=N)
(d, 2H, J=5.78 Hz, pyridine–C-βH), 8.37 (s, 1H, CH=N), 8.82 (d, 2H, J=5.78 Hz,
pyridine–C-αH).
2b
2c
2d
3218 (NH), 1669 (C=O), 1654 (C=N)
3220 (NH), 1666 (C=O), 1655 (C=N)
7.21–7.62 (m, 4H, phenyl–H), 7.93 (d, 2H, J=5.78 Hz, pyridine–C-βH), 8.32 (s, 1H,
CH=N), 8.81 (d, 2H, J=5.78 Hz, pyridine–C-αH).
7.01–7.72 (m, 4H, phenyl–H), 7.89 (d, 2H, J=5.78 Hz, pyridine–C-βH), 8.40 (s, 1H,
CH=N), 8.84 (d, 2H, J=5.78 Hz, pyridine–C-αH).
3215 (NH), 1667 (C=O), 1653 (C=N) 7.18 (d, 2H, J=8.80 Hz, phenyl–C3,5H), 7.72(d, 2H, J=8.80 Hz, phenyl–C2,6H), 7.91
(d, 2H, J=5.78 Hz, pyridine–C-βH), 8.39 (s, 1H, CH=N), 8.81 (d, 2H, J=5.78 Hz,
pyridine–C-αH).
2e
2f
3209 (NH), 1670 (C=O), 1656 (C=N),
1522, 1305 (NO2)
7.72–8.11 (m, 3H, phenyl–C4,5,6H), 8.22 (d, 2H, J=5.78 Hz, pyridine–C-βH), 8.39 (s, 1H,
CH=N), 8.85 (d, 2H, J=5.78 Hz, pyridine–C-αH), 8.90 (s, 1H, phenyl–C3H).
3219 (NH), 1664 (C=O), 1656 (C=N) 2.16 (s, 6H, N–CH3)2), 6.52(d, 2H, J=8.80 Hz, phenyl–C3,5H), 6.73(d, 2H, J=8.80 Hz,
phenyl–C2,6H), 7.93 (d, 2H, J=5.78 Hz, pyridine–C-βH), 8.21 (s, 1H, CH=N), 8.82 (d,
2H, J=5.78 Hz, pyridine–C-αH).
2g
3542 (OH), 3227 (NH), 1665 (C=O), 3.81 (s, 3H,−OCH3), 6.90 (d, 1H, J=8.42 Hz, phenyl–C5H), 7.15 (d, 1H, J=8.42 Hz,
1657 (C=N)
phenyl–C6H), 7.41(s, 1H, phenyl–C2H), 8.15 (d, 2H, J=5.78 Hz, pyridine–C-βH), 8.42
(s, 1H, CH=N), 8.91 (d, 2H, J=5.78 Hz, pyridine–C-αH).
2h
4a
4b
4c
4d
4e
3124 (NH), 1662 (C=O), 1651 (C=N) 6.95 (m, 2H, phenyl–CH=CH–), 7.32–7.61 (m, 5H, phenyl–H), 8.23 (d, 1H, CH=N),
8.38 (d, 2H, J=5.78 Hz, pyridine–C-βH), 8.89 (d, 2H, J=5.78 Hz, pyridine–C-αH).
3284 (NH), 2220 (CN), 1654 (C=O)
3278 (NH), 2215 (CN), 1652 (C=O)
3274 (NH), 2217 (CN), 1649 (C=O)
3280 (NH), 2220 (CN), 1656 (C=O)
3279 (NH), 2219 (CN), 1655 (C=O)
7.09 (s, 1H, pyridine–C5H), 7.28–7.65 (m, 9H, phenyl–H), 12.87 (br s, 1H, NH, D2O
exchangeable).
7.13 (s, 1H, pyridine–C5H), 7.19–7.86 (m, 9H, phenyl–H), 12.88 (br s, 1H, NH, D2O
exchangeable).
6.92 (d, 2H, J=8.80 Hz, flourophenyl–C2,6H), 7.11 (s, 1H, pyridine–C5H), 7.36–7.78 (m,
flourophenyl–C3,5 H & phenyl–H), 12.91 (br s, 1H, NH, D2O exchangeable).
7.10 (s, 1H, pyridine–C5H), 7.22–7.94 (m, 8H, nitrophenyl–C4,5,6H & phenyl–H), 8.65
(d, 1H, J=8.64 Hz, nitrophenyl–C3 H), 12.88 (br s, 1H, NH, D2O exchangeable).
6.67 (d, 1H, J=5.22 Hz, Phenyl–CH=CH–),7.12 (s, 1H, pyridine–C5 H), 1.18 (d, 1H,
J=5.22 Hz, Phenyl–CH=CH–), 7.20–8.02 (m, 10H, phenyl–H), 12.89 (br s, 1H, NH, D2O
exchangeable).
5
2214 (CN); 1704 (C=O); 1256, 1123
(C–O–C)
1.24 (t, 3H, CH3), 3.15 (s, 6H,−N(CH3)2), 4.35 (m, 2H, CH2), 6.71 (d, 2H, J=8.75 Hz,
phenyl C2,6H), 7.92 (d, 2H, J=8.75 Hz, phenyl C3,5H), 8.12 (s, 1H,−C=CH).
and CQ diphosphate for their effect on schizont matura-
tion. Test compounds were dissolved in ethanol and fur-
ther diluted with RPMI-1640 medium (the final ethanol
concentration did not exceed 0.5%, which did not affect
parasite growth). CQ diphosphate was dissolved in aque-
ous medium. Test was done in duplicate wells for each
dose of the drugs. Solvent control culture containing the
same concentrations of the solvent as present in the test
wells was done with RPMI-1640 containing 10% AB (+)
serum.
Parasite growth was found to be unaffected by the
solvent concentrations used in the test. Growth of the
parasites from duplicate wells of each concentration was
monitored in Giemsa-stained blood smears by counting
number of schizont per 100 asexual parasites. Percent
schizont maturation inhibition was calculated by the
formula: (1 − Nt/Nc) × 100 where, Nt and Nc represent
the number of schizont in the test and control wells,
respectively.
each, Medical Research Institute, Alexandria University)
according to previously reported methods. e animals
weredividedintogroupsofsixmiceeach. ecompounds
were given orally, suspended in 1% gum acacia, in doses
of 1, 10, 100, 200, 250, 300 mg/kg. e mortality percent-
age in each group was recorded after 24 h18. Additionally
the test compounds were investigated for their parenteral
acute toxicity in groups of mice of six animals each. e
compounds or their vehicle, propylene glycol (control),
were given by intra-peritoneal injection in doses of 10,
25, 50, 75, 100 mg/kg. e percentage survival was fol-
Docking
e co-ordinate from the X-ray crystal structure of
dehydrofolate reductase (DHFR) enzyme used in this
simulation was obtained from the Protein Data Bank
(PDB ID: 1J3I), where the selective DHFR inhibitor
WR99210 is bound to the active site. e ligand mol-
ecules were constructed using the builder module and
were energy minimized. e active site of DHFR was
generated using the MOE-Alpha Site Finder, Molecular
Operating Environment’s (MOE-Dock 2005) module to
Acute toxicity
e oral acute toxicity of the most active compounds
2a, 2g and 2h was investigated using male mice (20 g
Journal of Enzyme Inhibition and Medicinal Chemistry