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Arch. Pharm. Chem. Life Sci. 2010, 343, 48–53
133.6 (Cp), 174.3 (C-2), 177.8 (C-4) ppm; MS (70 eV) m/z (%): 266
[M+] (23), 170 (37), 168 (100), 89 (49), 70 (25). Anal. calcd. for
C12H11ClN2OS: C, 54.03; H, 4.16; N, 10.50; S, 12.02. Found: C,
53.93; H, 4.11; N, 10.32; S, 12.12.
H-299), 3.72 (s, 3H, CH3O-p), 3.84 (s, 6H, CH3O-m), 6.94 (s, 2H, Ho),
7.58 (s, 1H, H-5') ppm; 13C-NMR (100 MHz, DMSO-d6) d: 39.3 (C-299),
39.7 (C-299), 56.0 (C-CH3O-p), 60.1 (2C-CH3O-m), 107.1 (Co), 128.5 (C-
5), 129.5 (Ci), 130.0 (C-59), 138.9 (Cp), 153.2 (Cm), 174.7 (C-2), 178.9
(C-4) ppm; MS (70 eV) m/z (%): 322 [M+] (57), 224 (100), 209 (64), 70
(27). Anal. calcd. for C15H18N2O4S: C, 55.89; H, 5.63; N, 8.69; S,
9.95. Found: C, 56.04; H, 5.42; N, 8.32; S, 10.16.
(Z)-2-(Dimethylamino)-5-(4-fluorobenzyliden)-1,3-thiazol-
4-one 4b
The compound was obtained as yellow solid in a yield of 49%.
M.p.: 2458C; FTIR (KBr) m: 1690 (C=O), 1623 (C=C), 1568 (C=N)
cm–1; 1H-NMR (400 MHz, DMSO-d6) d: 3.26 (s, 3H, H-299), 3.32 (s, 3H,
H-299), 7.38 (d, 2H, Hm, J = 9.2 Hz), 7.63 (s, 1H, H-59), 7.69 (d, 2H, Ho,
J = 9.2 Hz) ppm;13C-NMR (100 MHz, DMSO-d6) d: 39.8 (2C-299), 115.3
(d, Cm, 2JC-F = 21.0 Hz), 127.8 (C-59), 127.8 (Ci), 129.3 (C-5), 130.8 (d,
Co,3JC-F = 8.0 Hz), 161.8 (d, Cp, 1JC-F = 266.0 Hz), 174.4 (C-2), 177.9 (C-
4) ppm; MS (70 eV) m/z (%): 250 [M+] (25), 152 (100), 108 (22), 70
(20). Anal. calcd. for C12H11FN2OS: C, 57.59; H, 4.43; N, 11.19; S,
12.81. Found: C, 57.39; H, 4.24; N, 11.09; S, 12.57.
Antifungal evaluation
Microorganisms and media
For the antifungal evaluation, standardized strains from the
American Type Culture Collection (ATCC), Rockville, MD, USA,
and CEREMIC (C), Centro de Referencia en Micologica, Facultad
de Ciencias Bioquꢂmicas y Farmacꢁuticas, Suipacha 531-(2000)-
Rosario, Argentina, were used in a first instance of screening: C.
albicans ATCC 10231, S. cerevisiae ATCC 9763, C. neoformans ATCC
32264, A. flavus ATCC 9170, A. fumigatus ATTC 26934, A. niger
ATCC 9029, T. rubrum C 110, T. mentagrophytes ATCC 9972, and M.
gypseum C 115.
Active compound 4a was tested against ten clinical isolates of
Cryptococcus neoformans from Malbrꢀn Institute ((M) Av Vꢁlez
Sarsfield 563, Buenos Aires, Argentina). The numbers of voucher
specimens are presented in Table 2. Strains were grown on
Sabouraud-chloramphenicol agar slants for 48 h at 308C, main-
tained on slopes of Sabouraud-dextrose agar (SDA, Oxoid), and
subcultured every 15 days to prevent pleomorphic transforma-
tions. Inocula of cell or spore suspensions were obtained accord-
ing to reported procedures and adjusted to 1 to 56103 cells/
spores with colony forming units (CFU)/mL [28].
(Z)-5-Benzyliden-2-(dimethylamino)-1,3-thiazol-4-one 4c
The compound was obtained as yellow solid in a yield of 72%.
M.p.: 1848C; FTIR (KBr) m: 1679 (C=O), 1615 (C=C), 1578 (C=N)
cm–1;1H-NMR (400 MHz, DMSO-d6) d: 3.25 (s, 3H, H-299), 3.31 (3H, s,
H-299), 7,45 (t, 2H, Hp, J = 7.0 Hz), 7.52 (t, 2H, Hm, J = 7.3 Hz), 7.63 (s,
1H, H-5'), 7.62 (d, 2H, Ho, J = 7.24 Hz) ppm; 13C-NMR (100 MHz,
DMSO-d6) d: 39.3 (C-299), 39.9 (C-299), 129.1 (Cm), 129.3 (C-5), 129.4
(Co), 129.6 (C-59), 129.6 (Cp), 133.8 (Ci), 174.8(C-2), 178.9 (C-4) ppm;
MS (70 eV) m/z (%): 232 [M+] (24), 134 (100), 89 (19), 70 (14). Anal.
calcd. for C12H12N2OS: C, 62.04; H, 5.21; N, 12.06; S, 13.80. Found:
C, 62.17; H, 5.11; N, 12.23; S, 13.64.
(Z)-2-(Dimethylamino)-5-(4-methoxybenzyliden)-1,3-
thiazol-4-one 4d
Antifungal susceptibility testing
The minimal inhibitory concentration (MIC) of each compound
was determined by using broth microdilution techniques
according to the guidelines of the Clinical and Laboratory Stand-
ards Intitute (CLSI, formerly National Committee for Clinical
Laboratory Standards [28] for yeasts (M27-A2) and for filamen-
tous fungi (M38-A). MIC values were determined in RPMI-1640
(Sigma, St. Louis, Mo, USA) buffered to pH = 7.0 with MOPS.
Microtiter trays were incubated at 358C for yeasts and hialohy-
phomycetes and at 28–308C for dermatophyte strains in a
moist, dark chamber. MICs were visually recorded at 48 h for
yeasts, and at a time according to the control fungus growth, for
the rest of fungi.
For the assay, stock solutions of pure compounds were two-
fold diluted with RPMI-1640 from 256 to 0.98 lg/mL (final vol-
ume = 100 lL) and a final DMSO concentration f1%. A volume of
100 lL of inoculum suspension was added to each well with the
exception of the sterility control where sterile water was added
to the well instead. Ketoconazole, Terbinafine, Amphotericin B,
and Itraconazole were used as positive controls.
Endpoints were defined as the lowest concentration of drug
resulting in total inhibition (MIC100) of visual growth compared
to the growth in the control wells containing no antifungal com-
pound.
The minimum fungicidal concentration (MFC) of each com-
pound against each isolate was also determined as follows: After
determining the MIC, an aliquot of 5 lL sample was withdrawn
from each clear well of the microtiter tray and plated onto a 150-
mm RPMI-1640 agar plate buffered with MOPS (Remel, Lenexa,
Kans.). Inoculated plates were incubated at 308C, and MFCs were
recorded after 48 h. The MFC was defined as the lowest concen-
The compound was obtained as yellow solid in a yield of 69%.
M.p.: 1758C; FTIR (KBr) m: 1679 (C=O), 1599 (C=C), 1576 (C=N)
cm–1; 1H-NMR (400 MHz, DMSO-d6) d: 3.24 (s, 3H, H-299), 3.30 (s, 3H,
H-299), 3.82 (s, 3H, CH3O-p), 7.08 (d, 2H, Hm, J = 8.7 Hz), 7.58 (d, 2H,
H-o, J = 8.7 Hz), 7.58 (s, 1H, H-5') ppm; 13C-NMR (100 MHz, DMSO-
d6) d: 39.3 (C-299), 39.8 (C-299), 55.4 (C-CH3O-p), 131.7 (Co), 114.7
(Cm), 126.3 (Ci), 126.4 (C-5), 129.6 (C-59), 160.4 (Cp), 174.7 (C-2),
179.2 (C-4) ppm; MS (70 eV) m/z (%): 262 [M+] (29), 164 (100), 149
(49), 70 (11). Anal. calcd. for C13H14N2O2S: C, 59.52; H, 5.38; N,
10.68; S, 12.22. Found: C, 59.37; H, 5.47; N, 10.52; S, 12.31.
(Z)-2-(Dimethylamino)-5-(4-nitrobenzyliden)-1,3-thiazol-
4-one 4e
The compound was obtained as yellow solid in a yield of 70%.
M.p.: 2828C; FTIR (KBr) m: 1709 (C=O), 1596 (C=C), 1582 (C=N)
cm–1; 1H-NMR (400 MHz, DMSO-d6) d: 3.30 (s, 3H, H-299), 3.30 (s, 3H,
H-299), 7.68 (s, 1H, H-59), 7.82 (d, 2H, Ho, J = 8.5 Hz), 8.27 (d, 2H, Hm,
J = 8.5 Hz) ppm; 13C-NMR (100 MHz, DMSO-d6) d: 39.8 (C-299), 39.8
(C-299), 123.3 (Cm), 126.3 (C-59), 129.5 (Co), 133.7 (C-5), 140.1 (Ci),
144.6 (Cp), 174.1 (C-2), 177.4 (C-4) ppm; MS (70 eV) m/z (%): 277
[M+] (50), 260 (10), 179 (100), 149 (24), 133 (17), 89 (74), 70 (48).
Anal. calcd. for C12H11N3O3S: C, 51.98; H, 4.00; N, 15.15; S, 11.56.
Found: C, 52.14; H, 4.17; N, 15.01; S, 12.14.
(Z)-2-(Dimethylamino)-5-(3,4,5-trimethoxybenzyliden)-
1,3-thiazol-4-one 4f
The compound was obtained as yellow solid in a yield of 64%.
M.p.: 2068C; FTIR (KBr) m: 1677 (C=O), 1583 (C=C), 1570 (C=N)
cm–1;1H-NMR (400 MHz, DMSO-d6) d: 3.26 (s, 3H, H-299), 3.31 (s, 3H,
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