Synthesis and evaluation of novel indolylthiadiazinoazetidinones and indolylthiadiazinothiazolidinones as antimicrobial agents

Article abstract of DOI:10.1002/ardp.200900203

Some new 5-methoxy/ethoxy-2,3-[2′-(3″-chloro-2″-oxo- 4″-substituted-aryl-1″-azetidinyl)-1′,3′, 4′-thiadiazino] indoles 13-20 and 5-methoxy/ethoxy-2,3-[2′- (2″-substituted-aryl-4″-oxo-1″,3″-thiazolidin-3″- yl)-1′,3′,4′-thiadiazino]indoles 21-28 have been s

Full text of DOI:10.1002/ardp.200900203

98
Arch. Pharm. Chem. Life Sci. 2010, 343, 98–107
Full Paper
Synthesis and Evaluation of Novel
Indolylthiadiazinoazetidinones and
Indolylthiadiazinothiazolidinones as Antimicrobial Agents
Vikas Kumar1, Suneel Kumar Sharma1, Sheoraj Singh1, Ashok Kumar1, and Shalabh Sharma2
1 Medicinal Chemistry Division, Department of Pharmacology, L. L. R. M. Medical College, Meerut (U. P.),
India
2 Department of Chemistry, D. J. College of Engineering & Technology, Modinagar (U. P.), India
Some new 5-methoxy/ethoxy-2,3-[29-(399-chloro-299-oxo-499-substituted-aryl-199-azetidinyl)-19,39,49-thia-
diazino]indoles 13–20 and 5-methoxy/ethoxy-2,3-[29-(299-substituted-aryl-499-oxo-199,399-thiazolidin-
399-yl)-19,39,49-thiadiazino]indoles 21–28 have been synthesized from 5-methoxy/ethoxy-2,3-[29-(sub-
stituted-benzylidinylimino)-19,39,49-thiadiazino]indoles 5–12. These newly synthesized com-
pounds were characterized by elemental and spectral analysis. Further, compounds 5–28 of the
present series have been screened for their antibacterial and antifungal activities. Both minimal
inhibitory concentration (MIC) and inhibition zones were determined in order to monitor the
efficacy of the synthesized compounds. Compounds 14 and 16 were found to be the most potent
members of the present series, they showed maximal antibacterial and antifungal properties
much better than the standard drugs.
Keywords: Antibacterial activity / Antifungal activity / Azetidinone / Indolylthiadiazine / Thiazolidinone /
Received: August 9, 2009; accepted: October 19, 2009
DOI 10.1002/ardp.200900203
insecticidal [6], anti-inflammatory [7–9], etc. Similarly,
Introduction
thiadiazine [10–11], thiazolidinone [12–13], and azetidi-
none [14–15] derivatives have also been found to exhibit
antibacterial and antifungal activities. The present study
discusses the wide range of activities associated with
indole, thiadiazine, thiazolidinone, and azetidinone
moieties, and prompted us to synthesize indolylthiadi-
azinoazetidinones and indolylthiadiazinothiazolidi-
nones derivatives; they were screened for antibacterial
and antifungal activities.
Combat against bacterial and fungal infection has
resulted in the development of a wide variety of antimi-
crobial drugs. After years of misuse and overuse of these
drugs, microorganisms are becoming resistant resulting
in a potential global health problem. It is evident that
antimicrobial resistance is associated with an increase in
mortality. Hence, there is still a critical need for new anti-
microbial agents to treat life-threatening diseases. Thus,
various scientists are engaged to synthesize new com-
pounds related to various chemical groups like indole,
thiazole, thiazolidinone, azetidinone, etc.
Chemistry
The indole derivatives are well known in medicinal
chemistry due to their diverse biological properties like
antimicrobial [1], antibacterial [2–3], antifungal [4–5],
The synthetic route of the title compounds is outlined in
Scheme 1. The starting compounds: 5-methoxy-3-thiose-
micarbazido-indol-2-one 1 and 5-ethoxy-3-thiosemicarba-
zido-indol-2-one 2 were prepared from the reactions of 5-
methoxy-indol-2,3-dione and 5-ethoxy-indol-2,3-dione
with thiosemicarbazide, respectively. Compounds 1 and
2, on treatment with concentrated H2SO4, yielded thiadi-
Correspondence: Dr. Shalabh Sharma, Assistant Professor, Depart-
ment of Chemistry, D. J. College of Engineering & Technology, Niwari
Road, Modinagar-201 204 (U. P.), India.
E-mail: drshalabhsharma@gmail.com
Fax: +91 1232 220 287
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Arch. Pharm. Chem. Life Sci. 2010, 343, 98–107
Indolylthiadiazino-azetidinones and -thiazolidinones
99
respectively. The structural assignments of the above
newly synthesized compounds were based on elemental
(C, H, N) and spectral (IR,1H-NMR, Mass) analysis.
Results and discussion
The antibacterial activity of compounds 5, 28 and the
standard drug chloroamphenicol, was carried out
against Escherichia coli ATCC 25922, Bacillus subtilis ATCC
1633, and Staphylococcus aureus ATCC 25923. Results
showed the varying degree of antibacterial activity of all
the compounds tested (Tables 1 and 2). From the results it
is clear that compounds 14 and 16 showed excellent anti-
bacterial activity, MIC: 3.125 lg/mL (Table 2), better than
the standard drug and good inhibition zones against all
the bacterial strains (Table 1). Compounds 15 and 24
exhibited higher activity against E. coli ATCC 25922 and S.
aureus ATCC 25923 than the standard drug with MIC: 6.25
lg/mL. Compound 19 showed to be more potent against
S. aureus ATCC 25923 than the standard drug with MIC:
6.25 lg/mL. Further, many compounds (13, 18, 20, and
22) displayed antibacterial properties equipotent to the
reference drug. The other compounds of this series
showed a moderate activity as compared to standard
drug.
Compounds 5, 28 along with the reference drug fluco-
nazole were also tested for antifungal activity against
Candida albicans ATCC 2091, Aspergillus niger ATCC 9029,
and Candida krusei ATCC 6518. The results of the antifun-
gal screening revealed that all the tested compounds 5–
28 showed moderate to good antifungal properties
(Tables 1 and 2). Out of these compounds tested, com-
pounds 14 and 16 were found to be more potent antifun-
gal agents against C. albicans ATCC 2091, A. niger ATCC
9029, and C. krusei ATCC 6518 than the reference drug:
their MIC values were determined to be 3.125, 6.25, and
1.592 lg/mL, respectively (Table 2). Compounds 21, 22,
and 24 displayed antifungal property equipotent to the
reference drug against all three fungal strains. The other
compounds of this series were less active compared to
the standard drug.
Compounds 5–12 exhibited mild to moderate antibac-
terial and antifungal activities. Out of these compounds
5–12, compounds 5–8, having a methoxy-group substitu-
tion at the 5-postion of the indole nucleus, produced bet-
ter activities compared to compounds 9–12 bearing an
ethoxy group at the same position. Cyclization of com-
pounds 5–12 into their corresponding azetidinone con-
geners 13–20 markedly enhanced the antibacterial and
antifungal activities. Again, it is interesting to point out
that the methoxy-group substitution 13–16 showed supe-
R = -OCH3 /-OC2H5; R1 = substituted aryl.
Scheme 1. Synthetic route to novel compounds.
azine congeners i. e., 5-methoxy-2,3-(29-amino-19,39,49-thia-
diazino)indole 3 and 5-ethoxy-2,3-(29-amino-19,39,49-thia-
diazino)indole 4, respectively. Further, compounds 3 and
4 were converted into Schiff bases: 5-methoxy-2,3-[29-(sub-
stituted-benzylidinylimino)-19,39,49-thiadiazino)indoles
5–8 and 5-ethoxy-2,3-[29-(substituted-benzylidinylimino)-
19,39,49-thiadiazino)indoles 9–12, respectively, on reac-
tion with proper substituted aromatic aldehydes in the
presence of a few drops of glacial acetic acid. Further-
more, compounds 5-methoxy-2,3-[29-(399-chloro-299oxo-499-
substituted-aryl-199-azetidinyl)-19,39,49-thiadiazino]indoles
13–16 and 5-ethoxy-2,3-[29-(399-chloro-299-oxo-499-substi-
tuted-aryl-199-azetidinyl)-19,39,49-thiadiazino) indoles 17–
20 have been procured from compounds 5–8 and 9–12,
respectively, on treatment with triethyl amine/chloroace-
tyl chloride. Compounds 5–8 and 9–12 were also reacted
with thioglycolic acid/zinc chloride to afford the thiazoli-
dinone derivatives: 5-methoxy-2,3-[29-(299-substituted-aryl-
499-oxo-199,399-thiazolidin-399-yl)-19,39,49-thiadiazino]indoles
21–24 and 5-ethoxy-2,3-[29-(299-substituted-aryl-499-oxo-
199,399-thiazolidin-399-yl)-19,39,49-thiadiazino]indoles 25–28,
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V. Kumar et al.
Arch. Pharm. Chem. Life Sci. 2010, 343, 98–107
Table 1. Inhibitory-zone diameter (in mm) of the synthesized compounds 5–28 against the tested bacterial and fungal strains.
Compound
Antibacterial activitya)
Antifungal activitya)
Diameter of the inhibition zone (in mm)
Diameter of the inhibition zone (in mm)
E. coli
B. subtilis
S. aureus
C. albicans
A. niger
C. krusei
ATCC 25922
ATCC 1633
ATCC 25923
ATCC 2091
ATCC 9029
ATCC 6258
5
6
7
8
10
18
12
14
8
9
13
14
16
7
10
15
12
18
–
–
14
9
11
–
–
12
7
9
–
–
10
–
9
–
9
10
11
12
16
12
9
6
–
6
8
–
7
12
7
8
10
5
7
8
–
7
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
25
36
28
31
24
26
21
24
16
28
18
23
14
22
21
18
0
24
26
21
25
15
20
17
19
11
18
–
14
11
–
12
15
0
21
32
25
29
20
21
24
22
12
23
16
21
12
18
–
20
33
20
31
17
16
17
16
24
30
25
23
21
26
23
21
0
19
25
17
24
10
15
16
18
21
–
20
–
17
19
–
14
22
15
21
10
14
10
10
16
18
–
19
–
–
14
16
0
28
–
0
18
0
Controlb)
Chloroamphenicol
Fluconazole
26
–
23
–
22
–
–
29
–
22
–
19
a)
Concentration was 250 lg/mL.
DMSO.
b)
– Denotes: no inhibition zone was observed.
ratus, and are uncorrected. The purity of the newly synthesized
compounds was checked by thin layer chromatography (TLC) on
silica gel-G-coated plates by using different solvent systems.
Infrared (IR) spectra were determined on Bruker IFS-66 FTIR
(Bruker Bioscience, USA) using KBr pallets and the wave number
riority over the ethoxy-group substitution 17–20 in
terms of the biological profile of the said compounds.
Moreover, conversion of compounds 5–12 into their thia-
zolidinone derivatives 21–28 also enhanced the antibac-
terial and antifungal activities, but this increase of the
biological profile of these compounds 21–28 is not very
significant compared to the azetidnone congeners 13–
20. It can be concluded that azetidinone congeners 13–
20 produced a better protection against various patho-
gens compared to the thiazolidinone congeners 21–28.
The physicochemical characteristics and the spectral
data are given in Table 3.
1
(m) was reported in cm– 1. H-NMR spectra were taken on a Jeol
GSX-300 FT NMR (Jeol, Tokyo, Japan) in CDCl3 or DMSO-d6, and
chemical shifts (d) are given in ppm. Tetramethylsilane (TMS)
was used as internal reference standard. Mass spectra were
recorded on Spec Finnigan Mat 8230 MS (Thermo Electron Cor-
poration). The carbon, hydrogen, and nitrogen analyses were
performed on a Carlo Erba-1108 (Carlo Erba, Milan, Italy), and
the results were found within l 0.4% of the theoretical values.
Chemistry
General procedure for the synthesis of 5-methoxy-3-
thiosemicarbazido-indol-2-one 1
Experimental
To the methanolic solution of 5-methoxy-indol-2,3-dione (0.01
mol), thiosemicarboazide (0.01 mol) was added. This reaction
mixture was refluxed for 4 h, and then, the excess of solvent has
been removed by distillation. After this, the residue was allowed
to cool then it was poured onto crushed ice, filtered, and washed
with water. The solid mass obtained was recrystallized from
General
All the reagents and solvents were received form commercial
supplier. Reactions were done in dried glassware. Melting points
were taken in open capillaries by thermonic melting point appa-
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Arch. Pharm. Chem. Life Sci. 2010, 343, 98–107
Indolylthiadiazino-azetidinones and -thiazolidinones
101
Table 2. Minimal inhibitory concentration (MIC) lg/mL of synthesized compounds 5–28 against tested bacterial and fungal strains.
Compound
Minimal inhibitory concentration (MIC) (lg/mL)
E. coli
B. subtilis
S. aureus
C. albicans
A. niger
C. krusei
ATCC 25922
ATCC 1633
ATCC 25923
ATCC 2091
ATCC 9029
ATCC 6258
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
125
50
100
50
25
100
50
100
25
–
125
–
125
12.5
3.125
6.25
3.125
50
12.5
6.25
12.5
100
12.5
50
–
–
–
100
–
125
–
125
–
125
12.5
1.592
12.5
1.592
100
12.5
50
125
250
125
–
125
250
250
50
100
250
125
–
125
250
250
25
6.25
25
6.25
125
50
50
25
12.5
–
12.5
–
125
100
125
100
125
125
12.5
3.125
6.25
3.125
25
12.5
50
25
100
6.25
50
25
125
125
–
125
6.25
3.125
12.5
3.125
25
12.5
12.5
12.5
50
12.5
–
25
50
–
50
25
6.25
–
3.125
50
3.125
100
100
100
100
25
6.25
12.5
25
50
12.5
25
50
–
50
6.25
3.125
–
3.125
–
25
100
25
50
50
12.5
100
25
–
–
25
25
–
25
–
12.5
–
12.5
6.25
–
Chloroamphenicol
Fluconazole
12.5
–
12.5
–
6.25
3.125
– Denotes: no activity was observed.
ethanol to give compound 1. Yield: 76%, m.p.: 1818C; IR (KBr) m:
3380 (NH2), 3252 (NH), 3033 (C-H aromatic), 2910 (C-H aliphatic),
1675 (C=O), 1612 (C=N), 1535 (C-C of aromatic ring), 1520 (C-N-C),
1204 (C=S), 1180 (C-N), 1020 (N-N) cm– 1;1H-NMR (DMSO-d6) d: 8.60
(s, 1H, NH of indole, exchangeable with D2O), 7.75 (d, 1H, H7 of
indole, J = 9.0 Hz), 7.10 (d, 1H, H4 of indole, J = 9.0 Hz), 6.86 (dd,
1H, H6 of indole, J = 2.4 Hz, J = 9.0 Hz), 6.10 (bs, 2H, NH2, exchange-
able with D2O), 5.90 (s, 1H, NH, exchangeable with D2O), 3.25 (s,
3H, OCH3) ppm; MS (m/z): 250 [M+]. Anal. calcd. for C10H10N4O2S: C,
48.00; H, 4.00; N, 22.40. Found: C, 48.16; H, 4.28; N, 22.52.
C11H12N4O2S: C, 50.00; H, 4.55; N, 21.21. Found: C, 50.21; H, 4.27;
N, 21.45.
General procedure for the synthesis of 5-methoxy-2,3-(29-
amino-19,39,49-thiadiazino)indole 3
A mixture of compound 1 (0.05 mol) and concentrated H2SO4 (15
mL) was left to react at room temperature for around 16 h. Then,
this reaction mixture was poured onto crushed ice, neutralized
with liquid ammonia to get a solid mass, which was filtered and
washed with water, dried and recrystallized with methanol to
yield compound 3. Yield: 68%, m.p.: 1228C; IR (KBr) m: 3380 (NH2),
3085 (C-H aromatic), 2980 (C-H aliphatic), 1611 (C=N), 1585 (C-C
of aromatic ring), 1080 (N-N), 671 (C-S-C) cm– 1; 1H-NMR (CDCl3) d:
7.76 (d, 1H, H7 of indole, J = 9.0 Hz), 7.14 (d, 1H, H4 of indole, J =
9.0 Hz), 6.79 (dd, 1H, H6 of indole, J = 2.4 Hz, J = 9.0 Hz), 6.14 (s, 2H,
NH2, exchangeable with D2O), 3.23 (s, 3H, OCH3) ppm; MS (m/z):
232 [M+]. Anal. calcd. for C10H8N4OS: C, 51.72; H, 3.45; N, 24.14.
Found: C, 51.82; H, 3.33; N, 24.36.
General procedure for the synthesis of 5-ethoxy-3-
thiosemicarbazido-indol-2-one 2
The reaction of 5-ethoxy-indol-2,3-dione (0.01 mol), thiosemicar-
bazide (0.01 mol), as described for the synthesis of compound 1,
has led to the formation of compound 2, recrystallized from
methanol. Yield: 74%, m.p.: 1888C; IR (KBr) m: 3245 (NH), 3385
(NH), 3065 (C-H aromatic), 2965 (C-H aliphatic), 1672 (C=O), 1609
(C=N), 1565 (C-C of aromatic ring), 1525 (C-N-C), 1218 (C=S), 1025
(N-N) cm– 1 1H-NMR (DMSO-d6) d: 9.72 (s, 1H, NH of indole,
;
General procedure for the synthesis of 5-ethoxy-2,3-
(29-amino-19,39,49-thiadiazino)indole 4
exchangeable with D2O), 7.78 (d, 1H, H7 of indole, J = 9.0 Hz), 7.12
(d, 1H, H4 of indole, J = 9.0 Hz), 6.89 (d, 1H, H6 of indole, J = 2.4 Hz,
J = 9.0 Hz), 6.12 (s, 2H, NH2, exchangeable with D2O), 5.91 (s, 1H,
NH, exchangeable with D2O), 3.44 (m, 2H, -CH2CH3), 0.88 (t, 3H, -
CH2CH3, J = 6.0 Hz) ppm; MS (m/z): 264 [M+]. Anal. calcd. for
Compound 2 (0.05 mol) and concentrated H2SO4 (15 mL) were
treated in the same manner as explained for the formation of
compound 3 to procure compound 4 and recrystallized from
ethanol. Yield: 65%, m.p.: 1188C; IR (KBr) m: 3365 (NH2), 3075 (C-H
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aromatic), 2965 (C-H aliphatic), 1615 (C=N), 1573 (C-C of aromatic
lized with appropriate solvents to obtain compounds 21, 22, 23,
and 24. The characteristics and spectral data of compounds 21–
24 are given in Table 3.
1
ring), 1076 (N-N), 665 (C-S-C) cm– 1; H-NMR (DMSO-d6) d: 7.78 (d,
1H, H7 of indole, J = 9.0 Hz), 7.14 (d, 1H, H4 of indole, J = 9.0 Hz),
6.87 (dd, 1H, H6 of indole, J = 2.4 Hv, J = 9.0 Hz), 6.12 (s, 2H, NH2,
exchangeable with D2O), 3.42 (m, 2H, -CH2CH3), 0.89 (t, 3H,
-CH2CH3, = 6.0 Hz) ppm; MS (m/z): 246 [M+]. Anal. calcd. for
General procedure for the synthesis of 5-ethoxy-2,3-[29-
(299-substituted-aryl-499-oxo-199,399-thiazolidin-399-yl)-19,39,49-
thiadiazino]indoles 25–28
J
C11H10N4OS: C, 53.66; H, 4.07; N, 22.76. Found: C, 53.76; H, 4.24;
N, 22.92.
A similar procedure as described for the synthesis of compounds
21–24 has been adopted to synthesize compounds 25–28 from
compounds 9–12 and thioglycolic acid and zinc chloride. The
characterization data and spectral data of compounds 25–28
are furnished in Table 3.
General procedure for the synthesis of 5-methoxy-2,3-[29-
(substituted-benzylidinylimino)-19,39,49-thiadiazino]indoles
5–8
Equimolar amount of compound 3 (0.02 mol) and different aro-
matic aldehydes (0.02 mol) in methanol (55 mL) were refluxed
for 10–12 h in the presence of a few drops of glacial acetic acid.
Progress and completion of the reaction were checked by TLC.
After refluxing, the excess of solvent was distilled off and the
remanent substance was dropped in ice-water, filtered, dried,
and the solids thus obtained were recrystallized from appropri-
ate solvents to furnish compounds 5, 6, 7, and 8. Their character-
istics and spectral data are given in Table 3.
Biological studies
Minimal inhibitory concentration (MIC)
The antimicrobial activity was assayed in vitro by two-fold broth
dilution [16] against the bacteria strains Escherichia coli ATCC
25922, Bacillus subtilis ATCC 1633, and Staphyloccoous aureus ATCC
25923 and fungi Candida albicans ATCC 2091, Aspergillus niger
ATCC 9029, and Candida krusei ATCC 6258. The minimal inhibitory
concentrations (MIC, in lg/mL) were defined as the lowest con-
centrations of compound that completely inhibited the growth
of each strain. All compounds dissolved in dimethylsulfoxide
were added to the culture media. Mueller-Hinton Broth for bac-
teria and Sabouraud Liquid Medium for fungi were used to
obtain the final concentrations ranging from 250 to 1.592 lg/
mL. The amount of dimethylsulfoxide never exceeded 1% v/v.
Inocula consisted of 5.06104 bacteria/mL and 1.06103 fungi/mL.
The MICs were read after incubation at 378C for 24 h (bacteria)
and at 308C for 48 h (fungi). Media and media with 1% v/v dime-
thylsulfoxide were employed as growth controls. Chloroamphe-
nicol and fluconazole were used as reference antibacterial and
antifungal drugs, respectively. To detect the type of antimicro-
bial activity, subcultures were performed by transferring 100 lL
of each mixture remaining clear in 1 mL of fresh medium. The
minimal bactericidal concentrations (MBC, lg/mL) and the mini-
mal fungicidal concentrations (MFC, lg/mL) were read after
incubation at 378C for 24 h and at 308C for 48 h, respectively.
General procedure for the synthesis of 5-ethoxy-2,3-[29-
(substituted-benzylidinylimino)-19,3 9,49-
thiadiazino)indoles 9–12
The above procedure was adopted to synthesize compounds 9–
12 starting with compound 4 and proper aromatic aldehydes.
The characterization and spectral data of compounds 9–12 are
shown in Table 3.
General procedure for the synthesis of 5-methoxy-2,3-[29-
(399-chloro-299-oxo-499-substituted-aryl-199-azetidinyl)-
19,39,49-thiadiazino]indoles 13–16
To the solution of compounds 5, 6, 7, and 8 (0.01 mol) in dioxane
(50 mL), chloroacetyl chloride (0.02 mol) was added dropwise
with stirring in the presence of triethyl amine (0.01 mol) at 0–
58C. The different reaction mixtures were refluxed for 4 to 6 h
and excess of solvent was then distilled off. The resulting mix-
tures were poured into crushed ice to afford compounds 13, 14,
15, and 16. The physical and spectral data of these compounds
are given in Table 3.
Antibacterial activity
The newly synthesized compounds 5–28 were screened for anti-
bacterial activity against bacterial strains namely Escherichia coli
ATCC 25922, Bacillus subtilis ATCC 1633, and Staphylococcus aureus
ATCC 25923 at a concentration of 250 lg/mL by the filter-paper
disc-method [17]. For comparison, chloroamphenicol was used
as the standard drug. DMSO served as control and there was no
visible change in bacterial growth due to this. The discs of What-
man filter paper were prepared with standard size (7 mm) and
kept into one-Oz screw-capped wide-mouthed containers for
sterilization. These bottles are kept in the hot-air oven at 1508C.
Now, solution is put into each bottle. The discs are transferred to
the inoculated plates with a pair of fine pointed tweezers. To pre-
vent contamination, tweezers may be kept with their tips in 70%
alcohol and flamed off before use. Before the use of the test
organisms, which were grown on nutrient agar, they were sub
cultured in nutrient broth at 378C for 18–20 h. Each disc was
carefully applied to the surface of the agar without lateral move-
ment once the surface had been touched. Now, the plates incu-
bated for 24 h at 378C.
General procedure for the synthesis of 5-ethoxy-2,3-[29-
(399-chloro-299-oxo-499-substituted-aryl-199-azetidinyl)-
19,39,49-thiadiazino]indoles 17–20
Compounds 17–20 have been synthesized from compounds 9–
12 by following the procedure given for the synthesis of com-
pounds 13–16. The physical and spectral data of compounds
17–20 are depicted in Table 3.
General procedure for the synthesis of 5-methoxy-2,3-[29-
(299-substituted-aryl-499-oxo-199,399-thiazolidin-399-yl)-19,39,49-
thiadiazino]indoles 21–24
Thioglycolic acid (0.02 mol) and anhydrous ZnCl2 (0.02 mol)
were added to separate solutions of compounds 5, 6, 7, and 8
(0.02 mol) in DMF (50 mL). These reaction mixtures were
refluxed for 4–6 h and then distilled off. Further, residues were
poured on ice-water, filtered, washed with water, and recrystal-
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Arch. Pharm. Chem. Life Sci. 2010, 343, 98–107
Indolylthiadiazino-azetidinones and -thiazolidinones
107
[2] S. J. Biradar, Y. S. Manjunath, Indian J. Chem. 2004, 43B,
Antifungal activity
389–392.
The newly synthesized compounds 5–28 and the standard drug,
fluconazole were evaluated for their antifungal activity by
employing the standard agar disc diffusion method [18]. The fol-
lowing strains of fungi have been used in this study: Candida albi-
cans ATCC 2091, Aspergillus niger ATCC 9029, and Candida krusei
ATCC 6258. All cultures were maintained on (Sabouraud-dextrose
agar) SDA and incubated at 308C. To prepare homogeneous sus-
pensions of the above-mentioned fungi for the disc assays, they
were grown in Sabouraud broth, centrifuged to collect the pel-
let, and buffered with saline. The fungal pellet was homogenized
in a sterile hand-held homogenizer. This suspension was then
plated onto SDA using a fungal spreader to obtain an even
growth field. Sterile 6 mm Whatmann filter paper were impreg-
nated with 250 lg/mL concentrations of the various test com-
pounds and standard drug fluconazole. These discs were then
placed in the center of each quadrant of an SDA plate. Each plate
had one control disc impregnated with DMSO. The plates were
incubated at 308C. After 48 h, the plates were removed.
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The authors are thankful to the Sophisticated Analytical
Instrument Facility, Indian Institute of Technology, Madras,
Chennai, India for the spectral and elemental analyses and the
Head Department of Microbiology, L.L.R.M. Medical College,
Meerut, India for investigating the antifungal and antibacte-
rial activities.
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The authors have declared no conflict of interest.
585–589.
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of Clinical Microbiology, American Society for Microbiology
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