A. Arshad et al. / European Journal of Medicinal Chemistry 46 (2011) 3788e3794
3793
120.1, 118.9, 117.7, 116.8, 114.5, 112.8; MS (ESI): m/z
(100%) ¼ 364.0750 (MHþ). C19H14N3O3S (MHþ) requires 364.0750.
d, J ¼ 7.6 Hz), 7.82 (1H, s), 7.69 (1H, ddd, J ¼ 8.1, 7.5, 0.9 Hz), 7.64 (1H,
t, J ¼ 8.5 Hz), 7.62 (2H, dd, J ¼ 7.8,1.8 Hz), 7.46 (1H, d, J ¼ 8.1 Hz), 7.41
(1H, t, J ¼ 7.5 Hz); 13C NMR (
d, ppm, 100 MHz, DMSO-d6): 168.5,
4.6.3. 3-(2-(2-(4-Hydroxybenzylidene)hydrazinyl)thiazol-4-yl)-
2H-chromen-2-one (15c)
159.6, 153.2, 145.0, 142.7, 139.1, 134.5, 132.6, 130.8, 130.7, 130.3,
129.7, 128.1, 128.0, 127.1, 126.8, 126.5, 125.6, 124.9, 121.4, 120.1, 116.7,
111.6; MS (ESI): m/z (100%) ¼ 420.0778 (MNaþ). C23H15N3NaO2S
(MNaþ) requires 420.0777.
Dark brown small crystals. Recrystallized from CHCl3eEtOH
(1:3). Yield: 80%; mp: 249e250 ꢂC; IR KBr (cmꢀ1): 3424 (NH), 3212
(OH), 1706 (OeC]O), 1605 (C]N); 1H NMR (
d, ppm, 400 MHz,
DMSO-d6): 12.05 (1H, br s), 10.12 (1H, br s), 8.53 (1H, s), 7.97 (1H, s),
7.84 (1H, dd, J ¼ 7.6, 1.0 Hz), 7.74 (1H, s), 7.62 (1H, ddd, J ¼ 8.2, 7.6,
1.0 Hz), 7.51 (2H, d, J ¼ 8.6 Hz), 7.48 (1H, d, J ¼ 8.2 Hz), 7.38 (1H, t,
4.6.8. 3-(2-(2-(2-Hydroxy-1-naphthylidene)hydrazinyl)thiazol-4-
yl)-2H-chromen-2-one (15h)
Brown shiny powder. Recrystallized from EtOAceEtOH (2:1).
J ¼ 7.6 Hz), 6.82 (2H, d, J ¼ 8.6 Hz); 13C NMR (
d, ppm,100 MHz, DMSO-
Yield: 75%; mp: 272e274 ꢂC; IR KBr (cmꢀ1): 3439 (NH), 3207 (NH),
d6): 168.7, 159.7, 159.6, 153.2, 144.8, 143.1, 138.9, 132.5, 129.7, 128.9,
126.2,126.2,125.6,121.4,120.1,116.7,116.6,116.6,111.1; MS (ESI): m/z
(100%) ¼ 364.0750 (MHþ). C19H14N3O3S (MHþ) requires 364.0750.
1705 (OeC]O),1602 (C]N); 1H NMR (
d, ppm, 400 MHz, DMSO-d6):
12.26 (1H, br s), 10.95 (1H, br s), 8.99 (1H, s), 8.78 (1H, d, J ¼ 8.6 Hz),
8.59 (1H, s), 7.89e7.84 (3H, m), 7.82 (1H, s), 7.65 (1H, ddd, J ¼ 8.2, 7.5,
1.5 Hz), 7.58 (1H, t, J ¼ 7.5 Hz), 7.47 (1H, d, J ¼ 8.2 Hz), 7.41 (2H, ddd,
4.6.4. 3-(2-(2-(2,4-Dihydroxybenzylidene)hydrazinyl)thiazol-4-yl)-
2H-chromen-2-one (15d)
J ¼ 8.2, 7.2, 4.0 Hz), 7.24 (1H, d, J ¼ 8.4 Hz); 13C NMR (
d, ppm,100 MHz,
DMSO-d6): 168.0, 159.6, 157.3, 153.2, 145.2, 145.1, 139.2, 132.9, 132.6,
131.9, 129.8, 129.7, 129.1, 128.6, 125.6, 124.3, 124.0, 121.4, 120.1,
119.1, 116.8, 111.2, 111.1; MS (ESI): m/z (100%) ¼ 436.0739 (MNaþ).
C23H15N3NaO3S (MNaþ) requires 436.0726.
Yellow fluffy solid. Recrystallized from EtOH. Yield: 72%; mp:
271e274 ꢂC; IR KBr (cmꢀ1): 3466 (NH), 3270 (OH), 1697 (OeC]O),
1608 (C]N); 1H NMR (
d, ppm, 400 MHz, DMSO-d6): 11.95 (1H, br
s), 10.15 (1H, br s), 9.84 (1H, br s), 8.54 (1H, s), 8.25 (1H, s), 7.86
(1H, dd, J ¼ 7.4, 1.2 Hz), 7.74 (1H, s), 7.63 (1H, ddd, J ¼ 8.5, 7.4,
1.2 Hz), 7.47 (1H, d, J ¼ 8.6 Hz), 7.41 (1H, s), 7.39 (1H, t, J ¼ 7.4 Hz),
4.7. Biological activities
6.34 (2H, dd, J ¼ 7.5, 2.1 Hz); 13C NMR (
d
, ppm, 100 MHz, DMSO-
4.7.1. In vitro antibacterial and anti-fungal activity
d6): 168.3, 161.0, 159.6, 158.6, 153.2, 142.4, 139.0, 138.3, 132.5, 129.7,
129.2, 125.6, 121.4, 120.1, 116.8, 112.4, 110.8, 108.8, 103.4; MS (ESI):
m/z (100%) ¼ 380.0700 (MHþ). C19H14N3O4S (MHþ) requires
380.0700.
Antimicrobial activity of all synthesized compounds was
assessed against two Gram-positive bacteria (S. aureus ATCC 25923,
S. pyogenes ATCC 19615), one Gram-negative bacterium (H. influ-
enzae ATCC 10211) and a fungal strain (C. albicans ATCC 10231). The
minimum inhibition concentration (MIC) of the compounds was
determined by broth micro-dilution method [38]. The microbial
suspensions were prepared in Muller-Hinton broth from test
organisms sub-cultured on nutrient agar and incubated at 37 ꢂC for
48 h. The turbidity of the microbial suspensions was adjusted to
McFarland standard number 0.5. All compounds were dissolved in
DMSO and further diluted with water to prepare the working
4.6.5. 3-(2-(2-(2-Hydroxy-5-bromobenzylidene)hydrazinyl)
thiazol-4-yl)-2H-chromen-2-one (15e)
Bright yellow fluffy solid. Recrystallized from EtOAceEtOH (3:1).
Yield: 78%; mp: 296e298 ꢂC; IR KBr (cmꢀ1): 3430 (NH), 3260 (OH),
1701 (OeC]O), 1583 (C]N); 1H NMR
(d, ppm, 400 MHz,
DMSO-d6): 12.27 (1H, br s), 10.42 (1H, br s), 8.54 (1H, s), 8.29 (1H, s),
7.85 (1H, dd, J ¼ 7.5, 1.1 Hz), 7.78 (1H, s), 7.77 (1H, d, J ¼ 2.5 Hz), 7.65
(1H, ddd, J ¼ 8.3, 7.5, 1.1 Hz), 7.47 (1H, d, J ¼ 8.3 Hz), 7.40 (1H, t,
J ¼ 7.5 Hz), 7.36 (1H, dd, J ¼ 8.5, 2.5 Hz), 6.85 (1H, d, J ¼ 8.5 Hz); 13C
solution of 500
made in the range of 3.91e250
and inoculated with 100 L of the respective microbial strains. Two
mg/mL concentration. Serial two-fold dilutions were
mg/mL in 96 well micro-titre plates
m
NMR (
d
, ppm, 100 MHz, DMSO-d6): 168.3, 159.6, 155.9, 153.2, 139.1,
standard drugs, gentamicin and tetracycline were used as positive
controls while DMSO was used as a negative control in this assay.
The micro-titre plates were then sealed with parafilm and incu-
bated at 37 ꢂC for 24 h. After incubation, MTT [3-(4,5-
138.1, 133.6, 132.6, 129.7, 128.3, 125.6, 123.6, 121.4, 121.4, 120.0,
119.3, 116.8, 111.7, 111.5; MS (ESI): m/z (100%) ¼ 463.9696 (MNaþ).
C19H12BrN3NaO3S (MNaþ) requires 463.9675.
Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (50
mL,
4.6.6. 3-(2-(2-(2-Hydroxy-3-methoxybenzylidene)hydrazinyl)
thiazol-4-yl)-2H-chromen-2-one (15f)
0.2 mg/mL dissolved in sterilized distilled water) was added to each
well and plates were incubated again at 37 ꢂC for 30 min. The colour
of MTT changed from yellow to purple in the presence of biologi-
cally active microorganisms. The MIC was determined as the lowest
concentration of compounds required to prevent the colour
changes from yellow to purple.
Brown shiny solid. Recrystallized from EtOAceEtOH (2:1). Yield:
70%; mp: 266 ꢂC; IR KBr (cmꢀ1): 3445 (NH), 3239 (OH), 1704
(OeC]O), 1600 (C]N); 1H NMR (
d, ppm, 400 MHz, DMSO-d6):
12.17 (1H, br s), 9.45 (1H, br s), 8.55 (1H, s), 8.39 (1H, s), 7.86 (1H, dd,
J ¼ 7.5, 0.9 Hz), 7.77 (1H, s), 7.63 (1H, ddd, J ¼ 8.3, 7.5, 0.9 Hz), 7.46
(1H, d, J ¼ 8.3 Hz), 7.42 (1H, t, J ¼ 7.5 Hz), 7.27 (1H, d, J ¼ 8.0 Hz), 6.98
4.7.2. Anti-tuberculosis activity
(1H, d, J ¼ 8.0 Hz), 6.84 (1H, t, J ¼ 8.0 Hz), 3.83 (3H, s); 13C NMR (
d,
A well characterized virulent strain, M. tuberculosis H37Rv ATCC
27294 was used for the screening of anti-tuberculosis activity. The
mycobacterium inoculum was prepared from a log phase culture in
Middle brook 7H9 broth (Difco, USA) supplemented with albumin,
dextrose, and catalase (ADC) (Difco, USA), and its turbidity was
adjusted to McFarland standard no. 1 (approximately 3 ꢃ 107 CFU/
mL). The bacterial suspension was further diluted 1:20 in Middle
brook 7H9 broth supplemented with OADC. The anti-tuberculosis
activity was evaluated by a colourimetric tetrazolium micro plate
assay (TEMA) as reported in the literature [39] with some modifi-
ppm, 100 MHz, DMSO-d6): 168.4, 159.6, 153.2, 148.9, 146.3, 140.5,
139.1, 132.6, 129.7, 125.6, 123.3, 121.4, 121.4, 120.1, 120.1, 118.5, 116.8,
113.4, 111.3, 56.7; MS (ESI): m/z (100%) ¼ 392.0696 ([MꢀHþ]).
C20H14N3O4S ([MꢀHþ]) requires 392.0700.
4.6.7. 3-(2-(2-(1-Naphthylidene)hydrazinyl)thiazol-4-yl)-2H-
chromen-2-one (15g)
Dark yellow powder. Recrystallized from EtOAceEtOH (3:1).
Yield: 70%; mp: 262e265 ꢂC (Lit. mp and yield [37] 240e242 ꢂC,
70%); IR KBr (cmꢀ1): 3424 (NH), 1702 (OeC]O), 1594 (C]N); 1H
cations. First, sterile distilled water (200 mL) was added to all outer
NMR (
d
, ppm, 400 MHz, DMSO-d6): 12.31 (1H, br s), 8.77 (1H, d,
wells of a sterile 96-well micro plate (TPP, Germany). One hundred
micro litre of Middle brook 7H9 broth supplemented oleic acid,
J ¼ 8.5 Hz), 8.71 (1H, s), 8.58 (1H, s), 8.01 (2H, t, J ¼ 7.8 Hz), 7.87 (2H,