A note on the antitubercular activities of 1-aryl-5- benzylsulfanyltetrazoles

Article abstract of DOI:10.1002/ardp.200400967

A set of 32 1-phenyl-5-benzylsulfanyltetrazoles substituted on the phenyl ring as well as on the benzyl moiety was synthesized. The compounds were evaluated for in vitro antimycobacterial activity against Mycobacterium tuberculosis. The activity against M. tuberculosis becomes higher with increasing electron-accepting properties of the substituents on the phenyl ring. On the other hand, any substitution on the benzylic moiety decreases the activity.

Full text of DOI:10.1002/ardp.200400967

Arch. Pharm. Chem. Life Sci. 2005, 338, 385−389
DOI 10.1002/ardp.200400967
385
A Note on the Antitubercular Activities of 1-Aryl-5-
benzylsulfanyltetrazoles
a
a
b
ˇ´
ˇa
´
Jan Adamec , Karel Waisser , Jirı Kunes , Jarmila Kaustova
a Department of Inorganic and Organic Chemistry, Charles University, Faculty of Pharmacy, Hradec
´
´
Kralove, Czech Republic
b Department for Diagnostics of Mycobacteria, Regional Institute of Public Health, Ostrava, Czech
Republic
A set of 32 1-phenyl-5-benzylsulfanyltetrazoles substituted on the phenyl ring as well as on the benzyl
moiety was synthesized. The compounds were evaluated for in vitro antimycobacterial activity against
Mycobacterium tuberculosis. The activity against M. tuberculosis becomes higher with increasing elec-
tron-accepting properties of the substituents on the phenyl ring. On the other hand, any substitution
on the benzylic moiety decreases the activity.
Keywords: Benzylsulfanyltetrazoles; Mycobacterium tuberculosis; Tuberculostatics; Phase-transfer catalysis
Received: December 8, 2004; Accepted: June 2, 2005
Introduction
The search for structurally novel tuberculostatics is the cen-
tral theme of research in our group. In previous studies,
we focused on antimycobacterial compounds containing the
alkylsulfanyl group [1Ϫ4], which was identified as a
pharmacophore of antimycobacterial activity [5]. Recently,
we found that substitution with the benzylsulfanyl group
increases the activity of 1-aryl-5-alkylsulfanyltetrazoles [6].
The goal of this study was to determine the structure-
activity relationships in the group of the 1-aryl-5-benzylsul-
fanyltetrazoles substituted on both the phenyl and benzyl
rings. In studying the relationships between the structure
and antimycobacterial activity, we followed up on the
Scheme 1. Synthesis and structures of 1-aryl-5-benzylsulf-
anyltetrazoles.
conclusions made in our previous work [6], i.e. that the
5-benzylsulfanyl derivatives are more active than other
5-alkylsulfanyl derivatives.
in Scheme 1. The chemical and physical data of the new 1-
phenyl-5-benzylsulfanyltetrazoles are summarized in Table
1. Compounds described in previous papers [6] have not
been included in the Table. NMR spectra are given in
Table 2.
Results
Chemistry
The starting 1-aryltetrazole-5-thiols were prepared from the
corresponding substituted anilines following an established
protocol [7, 8]. All 5-alkylsulfanyl-1-aryltetrazoles were pre-
pared by the alkylation of 1-aryltetrazol-5-thiols with sub-
stituted benzyl chlorides (purchased from Aldrich Chemical
Company, Prague, Czech Republic) in toluene/aqueous po-
tassium hydroxide systems using tetrabutylammonium bro-
mide as a phase transfer catalyst. Structures are summarized
Microbiology
The tetrazoles were tested for their in vitro antimycobacter-
ial activity against Mycobacterium tuberculosis CNCTC My
331/88, obtained from the Czech National Collection of
Type Cultures (CNCTC). The antimycobacterial activities
are summarized in Table 3. In several cases, the minimum
inhibitory concentration could not be determined due to the
limited solubility of the compounds.
Correspondance: Karel Waisser, Charles University in Prague,
Faculty of Pharmacy in Hradec Kralove, Heyrovskeho 1203,
CZ 500 05 Hradec Kralove, Czech Republic. Phone: ϩ42 49 506-
7276. Fax: ϩ42 49 551-4332, e-mail: waisser@faf.cuni.cz
´
´
´
´
´
© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

386
Waisser et al.
Arch. Pharm. Chem. Life Sci. 2005, 338, 385−389
Table 1. Physical data of the new compounds and yields of the syntheses.
Compounds
Mp [°C]
Yield [%]
Compounds
Mp [°C]
Yield [%]
1d
1e
1f
92Ϫ93
91Ϫ93
oil
93.5Ϫ94
124Ϫ125
113Ϫ114
95Ϫ97
104Ϫ106
74Ϫ75
84
78
49
92
87
76
92
51
77
76
72
4a
4b
4c
4e
5d
5e
5f
6a
6c
6e
6f
49Ϫ51
88Ϫ90.5
87.5Ϫ89
76Ϫ77.5
98.5Ϫ100
79Ϫ80.8
36.5Ϫ38
42Ϫ44
52
40
71
80
90
85
56
64
52
97
65
2a
2b
2c
2d
2e
3d
3e
3f
60Ϫ62
79Ϫ83
60.5Ϫ62.5
100Ϫ102
49Ϫ51
1
Table 2. H- and 13C-NMR spectra of 1-aryl-5-benzylsulfanyltetrazoles.
Compounds
1d
NMR, δ
1H NMR (300 MHz, CDCl3): δ 7.58Ϫ7.56 (bs, 4H, H2Ј, H3Ј, H5Ј, H6Ј), 7.55Ϫ7.49 (m, 5H, H2, H3, H4, H5, H6),
4.64 (s, 2H, SCH2).
13C NMR (75 MHz, CDCl3): δ 153.3, 139.6, 133.4, 130.2, 129.9 (q, J ϭ 32.6 Hz), 129.8, 129.6, 126.5 (q, J ϭ 272.6
Hz), 125.7 (q, J ϭ 3.7 Hz), 123.7, 36.7
1e
1H NMR (300 MHz, CDCl3): δ 7.56Ϫ7.47 (m, 5H, H2, H3, H4, H5, H6), 7.45Ϫ7.37 (m, 2H, H2Ј, H6Ј), 7.04Ϫ6.95
(m, 2H, H3Ј, H5Ј), 4.59 (s, 2H, SCH2).
13C NMR (75 MHz, CDCl3): δ 162.4 (d, J ϭ 247.4 Hz), 153.6, 133.4, 131.1 (d, J ϭ 3.4 Hz), 131.0 (d, J ϭ 8.3 Hz),
130.1, 129.7, 123.7, 115.7 (d, J ϭ 21.7 Hz), 36.7
1f
1H NMR (300 MHz, CDCl3): δ 7.55Ϫ7.49 (m, 5H, H2, H3, H4, H5, H6), 7.38Ϫ7.32 (m, AAЈ, BBЈ, 2H, H2Ј, H6Ј),
6.87Ϫ6.81 (m, AAЈ, BBЈ, 2H, H3Ј, H5Ј), 4.59 (s, 2H, SCH2), 3.78 (s, 3H, OCH3).
13C NMR (75 MHz, CDCl3): δ 159.4, 154.0, 133.6, 130.5, 130.0, 129.7, 127.0, 123.7, 114.2, 55.3, 37.2
2a
2b
2c
2d
1H NMR (300 MHz, DMSO): δ 7.87Ϫ7.79 (m, AAЈ, BBЈ, 2H, H2, H6), 7.58Ϫ7.52 (m, AAЈ, BBЈ, 2H, H3, H5),
7.44Ϫ7.37 (m, 2H, H2Ј, H6Ј), 7.35Ϫ7.23 (m, 3H, H3Ј, H4Ј, H5Ј), 4.58 (s, 2H, SCH2).
13C NMR (75 MHz, DMSO): δ 154.2, 136.3, 133.2, 132.4, 129.3, 128.8, 128.0, 126.8, 124.0, 37.0
1H NMR (300 MHz, CDCl3): δ 7.70Ϫ7.64 (m, AAЈ, BBЈ, 2H, H2, H6), 7.44Ϫ7.34 (m, 4H, H3, H5, H2Ј, H6Ј),
7.32Ϫ7.26 (m, AAЈ, BBЈ, 2H, H3Ј, H5Ј), 4.58 (s, 2H, SCH2).
13C NMR (75 MHz, CDCl3) δ 153.5, 134.2, 133.8, 133.0, 132.4, 130.6, 129.0, 125.2, 124.3, 36.9
1H NMR (300 MHz, CDCl3) δ 7.68Ϫ7.62 (m, AAЈ, BBЈ, 2H, H2, H6), 7.44Ϫ7.38 (m, AAЈ, BBЈ, 2H, H3, H5), 7.33Ϫ7.27
(m, AAЈ, BBЈ, 2H, H2Ј, H6Ј), 7.16Ϫ7.09 (m, AAЈ, BBЈ, 2H, H3Ј, H5Ј), 4.60 (s, 2H, SCH2), 2.33 (s, 3H, CH3).
13C NMR (75 MHz, CDCl3): δ 153.9, 138.2, 132.9, 132.5, 131.9, 129.5, 129.1, 125.2, 124.1, 37.6, 21.1
1H NMR (300 MHz, CDCl3): δ 7.70Ϫ7.64 (m, AAЈ, BBЈ, 2H, H2, H6), 7.57 (bs, 4H, H2Ј, H3Ј, H5Ј, H6Ј), 7.43Ϫ7.37
(m, AAЈ, BBЈ, 2H, H3, H5), 4.64 (s, 2H, SCH2).
13C NMR (75 MHz, CDCl3): δ 153.3, 139.4, 133.0, 132.3, 130.3 (q, J ϭ 33.0 Hz), 129.6, 125.7 (q, J ϭ 3.8 Hz), 125.4
(q, Jϭ274.4 Hz), 125.1, 124.3, 36.8
2e
3d
3e
3f
1H NMR (300 MHz, CDCl3): δ 7.70Ϫ7.63 (m, AAЈ, BBЈ, 2H, H2, H6), 7.45Ϫ7.36 (m, 4H, H3, H5, H2Ј, H6Ј),
7.04Ϫ6.95 (m, 2H, H3Ј, H5Ј), 4.59 (s, 2H, SCH2).
13C NMR (75 MHz, CDCl3): δ 162.4 (d, J ϭ 247.7 Hz), 153.6, 133.0, 132.4, 131.0, 131.0, (d, J ϭ 8.3 Hz), 125.1,
124.1, 115.7 (d, J ϭ 21.7 Hz), 36.8
1H NMR (300 MHz, CDCl3): δ 7.57 (bs, 4H, H2Ј, H3Ј, H5Ј, H6Ј), 7.55Ϫ7.49 (m, AAЈ, BBЈ, 2H, H2Ј, H6Ј), 7.49Ϫ7.44
(m, AAЈ, BBЈ, 2H, H3Ј, H5Ј), 4.65 (s, 2H, SCH2).
13C NMR (75 MHz, CDCl3): δ 153.4, 139.4, 136.3, 131.8, 130.1, 129.9 (q, J ϭ 33.0 Hz), 129.6, 125.9 (q, J ϭ 275.2
Hz), 125.8 (q, J ϭ 3.7 Hz), 125.0, 36.8
1H NMR (300 MHz, CDCl3): δ 7.53Ϫ7.36 (m, 6H, H2, H3, H5, H6, H2Ј, H6Ј), 7.04Ϫ6.94 (m, 2H, H3Ј, H5Ј), 4.60
(s, 2H, SCH2).
13C NMR (75 MHz, CDCl3): δ 162.4 (d, J ϭ 247.7 Hz), 153.6, 136.2, 131.9, 131.0, 131.0 (d, J ϭ 8.3 Hz), 130.0,
124.9, 115.7 (d, J ϭ 21.7 Hz), 36.8
1H NMR (300 MHz, CDCl3) δ 7.55Ϫ7.44 (m, 4H, H2, H3, H5, H6), 7.38Ϫ7.30 (m, AAЈ, BBЈ, 2H, H2Ј, H6Ј),
6.89Ϫ6.81 (m, AAЈ, BBЈ, 2H, H3Ј, H5Ј), 4.59 (s, 2H, CH2), 3.97 (s, 3H, OCH3).
13C NMR (75 MHz, CDCl3) δ 159.5, 154.0, 136.1, 132.0, 130.5, 130.0, 126.9, 125.0, 114.2, 55.3, 37.4.
© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Arch. Pharm. Chem. Life Sci. 2005, 338, 385−389
Table 2. (continued).
Antitubercular Activity of 1-Aryl-5-benzylsulfanyltetrazoles
387
Compounds
NMR, δ
4a
4b
1H NMR (300 MHz, CDCl3): δ 7.66 (d, 1H, J ϭ 2.5 Hz, H2), 7.61 (d, 1H, J ϭ 8.5 Hz, H5), 7.44Ϫ7.29 (m, 6H, H6,
H2Ј, H3Ј, H4Ј, H5Ј, H6Ј), 4.63 (s, 2H, SCH2).
13C NMR (75 MHz, CDCl3): δ 153.9, 134.9, 134.6, 134.0, 132.6, 131.4, 129.2, 128.9, 128.3, 125.6, 122.7, 37.9
1H NMR (300 MHz, CDCl3): δ 7.67 (d, 1H, J ϭ 2.5 Hz, H2), 7.62 (d, 1H, J ϭ 8.5 Hz, H5), 7.41 (dd, overlaped, 1H,
J ϭ 8.5 Hz, J ϭ 2.5 Hz, H6), 7.40Ϫ7.34 (m, AAЈ, BBЈ, 2H, H2Ј, H6Ј), 7.32Ϫ7.26 (m, AAЈ, BBЈ, 2H, H3Ј, H5Ј), 4.52
(s, 2H, SCH2).
13C NMR (75 MHz, CDCl3): δ 153.6, 134.7, 136.3, 134.1, 133.6, 132.5, 131.5, 130.6, 129.0, 125.5, 122.7, 37.0
4c
4e
5d
5e
1H NMR (300 MHz, CDCl3): δ 7.65 (d, 1H, J ϭ 2.5 Hz, H2), 7.60 (d, 1H, J ϭ 8.5 Hz, H5), 7.41 (dd, 1H, J ϭ 8.5
Hz, J ϭ 2.5 Hz, H6), 7.33Ϫ7.26 (m, AAЈ, BBЈ, 2H, H2Ј, H6Ј), 7.18Ϫ7.09 (m, AAЈ, BBЈ, 2H, H3Ј, H5Ј), 4.60 (s, 2H,
SCH2), 2.33 (s, 3H, CH3).
13C NMR (75 MHz, CDCl3): δ 154.0, 138.3, 134.5, 134.0, 132.6, 131.8, 131.4, 129.5, 129.1, 125.6, 122.7 37.7, 21.1
1H NMR (300 MHz, CDCl3): δ 7.67 (d, 1H, J ϭ 2.5 Hz, H2), 7.62 (d, 1H, J ϭ 8.5 Hz, H5), 7.44Ϫ7.37 (3H, m, H6,
H2Ј, H6Ј), 7.05Ϫ6.96 (m, 2H, H3Ј, H5Ј), 4.60 (s, 2H, SCH2).
13C NMR (75 MHz, CDCl3): δ 162.5 (d, J ϭ 247.9 Hz), 153.7, 134.7, 134.1, 132.5, 131.5, 131.0 (d, J ϭ 8.3 Hz), 130.8
(d, J ϭ 3.4 Hz), 125.5, 122.7, 115.8 (d, J ϭ 21.7 Hz), 37.0
1H NMR (300 MHz, CDCl3): δ 7.57 (bs, 4H, H2Ј, H3Ј, H5Ј, H6Ј), 7.41Ϫ7.30 (m, 4H, H2, H3, H5, H6), 4.63 (s, 2H,
SCH2), 2.43 (s, 3H, CH3).
13C NMR (75 MHz, CDCl3): δ 153.3, 140.7, 139.7, 130.9, 130.3, 130.3 (q, J ϭ 29.5 Hz), 129.6, 125.8 (q, J ϭ 272.3
Hz), 125.7 (q, J ϭ 4.0 Hz), 123.6, 36.6, 21.2
1H NMR (300 MHz, CDCl3): δ 7.44Ϫ7.29 (m, 6H, H2, H3, H5, H6, H2Ј, H6Ј), 7.04Ϫ6.95 (m, 2H, H3Ј, H5Ј), 4.58
(s, 2H, SCH2), 2.43 (s, 3H, CH3).
13C NMR (75 MHz, CDCl3): δ 162.4 (d, J ϭ 247.4 Hz), 153.6, 140.6, 131.2 (d, J ϭ 3.4 Hz), 131.0, 131.0 (d, J ϭ 8.3
Hz), 130.3, 123.6, 115.7, (d, J ϭ 21.7 Hz), 36.7, 21.2
5f
1H NMR (300 MHz, CDCl3): δ 7.42Ϫ7.28 (m, 6H, H2, H3, H5, H6, H2Ј, H6Ј), 6.87Ϫ6.80 (m, 2H, H3Ј, H5Ј), 4.57
(s, 2H, SCH2), 3.78 (s, 3H, OCH3), 2.42 (s, 3H, CH3).
13C NMR (75 MHz, CDCl3): δ 159.4, 153.9, 140.4, 131.0, 130.5, 130.2, 127.1, 123.6, 114.1, 55.2, 37.2, 21.2
6a
6c
1H NMR (300 MHz, CDCl3): δ 7.45Ϫ7.25 (m, 7H, H2, H6, H2Ј, H3Ј, H4Ј, H5Ј, H6Ј), 7.04Ϫ6.96 (m, 2H, H3, H5),
4.60 (s, 2H, SCH2), 3.86 (s, 3H, OCH3).
13C NMR (75 MHz, CDCl3): δ 160.7, 154.0, 135.3, 129.2, 128.8, 128.1, 126.2, 125.5, 114.8, 55.6, 37.5
1H NMR (300 MHz, CDCl3): δ 7.43Ϫ7.36 (m, AAЈ, BBЈ, 2H, H2, H6), 7.33Ϫ7.27 (m, AAЈ, BBЈ, 2H, H2Ј, H6Ј),
7.15Ϫ7.09 (m, AAЈ, BBЈ, 2H, H3Ј, H5Ј), 7.03Ϫ6.97 (m, AAЈ, BBЈ, 2H, H3, H5), 4.57 (s, 2H, SCH2), 3.85 (s, 3H,
OCH3), 2.32 (s, 3H, CH3).
13C NMR (75 MHz, CDCl3): δ 160.6, 154.1, 138.0, 132.1, 129.4, 129.1, 126.2, 125.4, 114.7, 55.6, 37.3, 21.1
6e
6f
1H NMR (300 MHz, CDCl3): δ 7.43Ϫ7.35 (m, 4H, H2, H6, H2Ј, H6Ј), 7.03Ϫ6.94 (m, 4H, H3, H5, H3Ј, H5Ј), 4.55
(s, 2H, SCH2), 3.85 (s, 3H, OCH3).
13C NMR (75 MHz, CDCl3): δ 162.4 (d, J ϭ 247.4 Hz), 160.7, 153.8, 131.2 (d, J ϭ 3.5 Hz), 130.9 (d, J ϭ 8.3 Hz),
126.1, 125.4, 115.6 (d, J ϭ 21.4 Hz), 114.8, 55.6, 36.6
1H NMR (300 MHz, CDCl3): δ 7.43Ϫ7.37 (m, AAЈ, BBЈ, 2H, H2, H6), 7.36Ϫ7.30 (m, AAЈ, BBЈ, 2H, H2Ј, H6Ј),
7.03Ϫ6.97 (m, AAЈ, BBЈ, 2H, H3, H5), 6.87Ϫ6.80 (m, AAЈ, BBЈ, 2H, H3Ј, H5Ј), 4.56 (s, 2H, SCH2), 3.85 (s, 3H,
OCH3), 3.78 (s, 3H, OCH3).
13C NMR (75 MHz, CDCl3): δ 160.6, 159.4, 154.1, 130.5, 127.1, 126.2, 125.5, 114.7, 114.1, 55.6, 55.2, 37.1
Discussion
on the phenyl ring. On the other hand, any substitution on
the benzylic moiety decreases the activity. The key factor
that imposes limitations on potential use of the compounds
was their low solubility in water. All 1-(4-bromophenyl)-5-
benzylsulfanyltetrazoles and 1-(4-chlorophenyl) derivatives
and 1-(3,4-dichlorophenyl) derivatives with lipophilic sub-
stituents on the benzyl ring were insoluble. Further research
has to be focused on electron-accepting substituents pos-
sessing a low lipophilicity in the phenyl ring.
In studying the relationship between the structure and anti-
mycobacterial activity, we followed up on the conclusions
made in our previous work [6], namely that 5-benzylsulfanyl
derivatives are more active than other 5-alkylsulfanyl de-
rivatives. Compounds 1a, 3a, and 4a were the most active
ones (approximately eight times less active than isoniazid).
The activity against M. tuberculosis becomes higher with
increasing electron-accepting properties of the substituents
© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

388
Waisser et al.
Arch. Pharm. Chem. Life Sci. 2005, 338, 385−389
Table 3. Minimum inhibitory concentrations of 1-aryl-5-benzylsulfanyltetrazoles.
Compound
R1
R2
MIC
[μmol/L]
Compound
R1
R2
MIC
[μmol/L]
1a
1b
1c
1d
1e
1f
2a
2b
2c
2d
2e
3a
3b
3c
3d
3e
H
H
H
H
H
H
4-Br
4-Br
4-Br
4-Br
4-Br
4-Cl
4-Cl
4-Cl
4-Cl
4-Cl
H
4-Cl
4-CH3
4-CF3
4-F
4-OCH3
H
16†
3f
4-Cl
4-OCH3
H
4-Cl
4-CH3
4-F
H
32
†,‡
4a
4b
4c
3,4-Cl2
3,4-Cl2
3,4-Cl2
3,4-Cl2
4-CH3
4-CH3
4-CH3
4-CH3
4-CH3
4-CH3
4-OCH3
4-OCH3
4-OCH3
4-OCH3
4-OCH3
16
62.5†
‡
‡
‡
‡
§
4e
62.5
5a†
5b†
5cδ
5d
5e
32†
‡
‡
‡
‡
‡
‡
4-Cl
4-Cl
4-CH3
4-CF3
4-F
4-OCH3
H
4-Cl
4-CH3
4-F
62.5†
‡
4-CH3
4-CF3
4-F
H
4-Cl
4-CH3
4-CF3
4-F
‡
5f
32
32
62.5
62.5
125
32
16†
6a
6bδ
6c
†,‡
†,‡
‡
6e
6f
‡
4-OCH3
†
‡
§
data from the ref. [6], not tested because of low solubility, not tested because of being an oil.
(TLC in toluene-aceton (φr ϭ 10 : 1). The toluene layer was washed
with water, dried over Na2SO4, filtered, and the solvent evaporated
under reduced pressure. The solid residue was dissolved in meth-
anol, passed through charcoal and recrystallized from ethanol-water
or purified by column chromatography (silica gel, mobile phase
petrolether-ethyl acetate (φr ϭ 9:1, or petrolether-ether 9:1).
Acknowledgments
This work was supported by project No. MSM 0021620822
of the Ministry of Education of the Czech Republic and by
Grant No. 42/G6/2005 of the Higher Education Develop-
ment Fund.
Microbiological assay
Antimycobacterial susceptibility testing
Experimental
The strains of M. tuberculosis CNCTC My 331/8, obtained from the
Czech National Collection of Type Cultures (CNCTC), National
Institute of Public Health, Prague, were used for the evaluation of
in vitro antimycobacterial activity. The antimycobacterial activity of
the compounds was determined in the Sula semisynthetic medium
(SEVAC, Prague, Czech Republic). This medium (with bovine
serum) is routinely used in the Czech Republic. Each strain was
General
The melting points were determined on
a Kofler apparatus
(C. Reichert, Vienna, Austria). The samples for analysis and anti-
mycobacterial tests were dried over P4O10 at 61°C and 530 Pa for 24
h. Elemental analysis were performed on a CHNS-O CE elemental
analyzer (Fisons EA 1110, Milano, Italy) and were within 0.4%
of the theoretical values. The IR spectra were measured in CHCl3
on a Nicolet Impact 400 apparatus (Nicolet Instruments Corpo-
ration, Madison, WI, USA) or in KBr pellets. TLC was performed
on silica gel plates precoated with a fluorescent indicator Silufol UV
254 ϩ 366 (Kavalier, Votice, Czech Republic), with petrolether-ethyl
acetate (φr ϭ 9:1), or petrolether-ether (φr ϭ 9:1) as the mobile
phase. The 1H-NMR and 13C-NMR spectra were recorded in
DMSO-d6 solution, or CDCl3-d solution at ambient temperature on
a Varian Mercury-Vx BB 300 spectrometer operating at 300 MHz
(Varian, Palo Alto, CA, USA). Chemical shifts were recorded as δ
(ppm) and were indirectly referenced to tetramethylsilane via the
solvent signal (DMSO-d6 2.49 for 1H or 39.7 13C; CDCl3-d 7.26 for
1H or 77.0 for 13C ).
ˇ
simultaneously inoculated into
a Petri dish containing the
Löwenstein-Jensen medium (from our lab) for the control of sterility
of the inoculum and its growth. The compounds were added to the
medium in DMSO solutions. The final concentrations were 1000,
500, 250, 125, 62.5, 31, 16, 8, 4, 2 μmol/L. The MICs were deter-
mined after incubation at 37°C for 14 days (see Table 3). MIC was
the lowest concentration of an antimycobacterially effective sub-
stance (on the above concentration scale), at which inhibition of the
growth of the mycobacteria occurred. The evaluation was repeated
three times and the values of the minimum inhibitory concentration
were the same. The minimum inhibitory concentration of isoniazid
is 2 μmol/L.
References
General Procedure for Preparation of 1-Aryl-5-benzylsulfanyl-
1,2,3,4-tetrazoles
ˇ
´
ˇ´
´
[1] V. Klimesova, J. Kocı, K. Waisser, J. Kaustova, Farmaco 2002,
57, 259Ϫ265.
Tetrabutylammonium bromide (200 mg, 0.6 mmol) was added to a
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