Linked pyridinyl-thiadiazoles: Design and synthesis as potential candidate for treatment of XDR and MDR tuberculosis

Article abstract of DOI:10.1016/j.ejmech.2015.07.039

Abstract Multi-drug resistant (MDR) and extremely drug resistant (XDR) Mycobacterium tuberculosis strains have turned tuberculosis (TB) as "on the verge of eradication" to "most life threatening" disease. Furthermore, synergy with HIV and other immunosuppressive disease have strengthened its prevalence. This research reports small molecule anti-infectives which are specifically potent against several strains and isolates of TB. The hit compound 7f has also proved to be active against almost 25 clinical isolates comparable to marketed anti-TB agents.

Full text of DOI:10.1016/j.ejmech.2015.07.039

Accepted Manuscript
Linked pyridinyl-thiadiazoles: Design & synthesis as potential candidate for treatment
of XDR and MDR tuberculosis
Mr. N.S. Mahajan, Dr. S.C. Dhawale
PII:
S0223-5234(15)30171-9
10.1016/j.ejmech.2015.07.039
EJMECH 8023
DOI:
Reference:
To appear in: European Journal of Medicinal Chemistry
Received Date: 30 May 2015
Revised Date: 13 July 2015
Accepted Date: 20 July 2015
Please cite this article as: N.S. Mahajan, S.C. Dhawale, Linked pyridinyl-thiadiazoles: Design &
synthesis as potential candidate for treatment of XDR and MDR tuberculosis, European Journal of
Medicinal Chemistry (2015), doi: 10.1016/j.ejmech.2015.07.039.
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ACCEPTED MANUSCRIPT
Linked pyridinyl-thiadiazoles: Design & synthesis as potential candidate for treatment
of XDR and MDR tuberculosis
Mr. N. S. Mahajan*, Dr. S. C. Dhawale
A substituted pyridinyl-thiadizole has been identified and then modified to yield 7f, a potent
antitubercular agent. The anti-XDR & MDR-TB activity is discussed using 25 different isolates.
Cl
O
N N
S
N
S
N
H
7f
MIC value = 0.07±0.04µm

ACCEPTED MANUSCRIPT
Title:
Linked pyridinyl-thiadiazoles: Design and synthesis as potential candidate for treatment of
XDR and MDR tuberculosis.
Authors:
1
2
Mr. N. S. Mahajan*, Dr. S. C. Dhawale
1
Department of Pharmaceutical Chemistry,
Adarsh College of Pharmacy,
Bhavani Nagar, Kundal Road,
VITA-443201, (Maharashtra), India
nsmahajanns@gmail.com
2
School of Pharmacy,
Swami Ramanand Teerth Marathwada University
Vishnupuri, NANDED-431 606, (Maharashtra), India
1

ACCEPTED MANUSCRIPT
Abstract:
Multi-drug resistant (MDR) and extremely drug resistant (XDR) mycobacterium tuberculosis
strains have turned tuberculosis (TB) as “on the verge of eradication” to “most life
threatening” disease. Furthermore, synergy with HIV and other immunosuppressive disease
have strengthened its prevalence. This research reports small molecule anti-infectives which
are specifically potent against several strains and isolates of TB. The hit compound 7f has
also proved to be active against almost 25 clinical isolates comparable to marketed anti-TB
agents.
Keywords:
MDR-TB, M. tuberculosis, pyridine, thiadiazole, Clinical isolates
2

ACCEPTED MANUSCRIPT
1
. Introduction:
Mycobacterium tuberculosis (MTB, M. tuberculosis), the etiological agent of tuberculosis
TB), is the leading cause of mortality due to bacterial pathogens, claiming about 2 million
(
lives annually. The field of anti-tuberculosis drug discovery culminated in the 1960s with the
incorporation of rifampicin and pyrazinamide in the tuberculosis drug regimen. The use of
these two antimicrobials, in combination with isoniazid, ethambutol and/or streptomycin,
represents a landmark in the treatment of human tuberculosis and resulted in the
implementation of short-course chemotherapy (SCC), reducing the time of treatment from 18
to 6 months [1-3]. Short-course chemotherapy contributed towards controlling tuberculosis
burden for the next 20 years. Nevertheless, tuberculosis cases started to rise again in the
1
990s under the pressure of the HIV pandemic and the emergence of multidrug-resistant
(MDR) and extremely drug-resistant (XDR) tuberculosis strains. MDR strains are resistant to
at least isoniazid (INH) and rifampicin (RIF), whereas XDR strains are MDR isolates that are
additionally resistant to fluoroquinolones and to one of the three injectable drugs
capreomycin, amikacin and kanamycin. The emergence and dissemination of MDR and XDR
isolates, estimated to account for more than 400,000 new cases per year, impart new
challenges in tuberculosis control [4]. Indeed, current treatment of drug-resistant tuberculosis
requires 18–36 months and is associated with an unacceptable rate of treatment failure and
relapse. Consequently, developing new compounds active against MDR and XDR
tuberculosis constitutes a main objective in anti-tuberculosis drug discovery. In addition, new
antimycobacterial agents should ideally contribute to shorten tuberculosis treatment to 2
months or less [5, 6]. Few promising drug candidates fulfilling these criteria have been
discovered in recent years [7-9]. Mainly, TMC207, which has been shown to be highly active
in proof-of-concept trials, and shows the potential to shorten the duration of therapy [10-11].
Recently, there are several reports citing pyridine and thiadiazoles as potential antibacterial
and anti-tubercular agent [12-15]. Inspired by the citations, we decided to design around the
heterocycles and evaluate the antimycobacterial activity of the same. Nonetheless, given the
number of tuberculosis cases and the rate of emergence of drug resistance, more compounds
are clearly needed to combat and have a significant impact on the control and spread of
tuberculosis. Thus in-continuation with the search of new drug candidate we herein discuss
this report about development of a lead to hit molecule.
2
. Results and Discussion:
2
.1. Chemistry
3

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In our attempt to synthesise cost effective drug, thiadiazole was identified as better target,
easy and cheaper to synthesis. The synthetic route was followed as reported in figure-1 [16].
In brief, the ester to hydrazide chemotransformation was carried out by using hydrazine
hydrate in ethanol at reflux condition. The hydrazide was then transformed to
thiosemicarbazate by usual CS , KOH and ethanol method. The resultant solid was then
2
cyclised using proton donar (sulphuric acid) at temperature ranging from 0 to 5 °C. The
pyridinyl-thiadiazole “parent” then reacted with various chloro-substituted compounds for
further analog synthesis. These reactions led us to the thio substituted array of compounds 5,
6
, 7 and 8.
2
.2. Antitubercular activity
A cellular screen was developed to identify mycobacterial growth inhibitors. The screen was
carried out against Mycobacterium bovis (M. bovis) BCG using intracellular ATP content as a
surrogate marker of bacillary growth. Compound hits with confirmed activity against M.
tuberculosis were chemically clustered to identify any emerging SAR. Our attention was
drawn to a cluster of pyridinyl-thiadiazole compound. One of the lead 4, (synthesized at our
laboratory for another program, unpublished) with an MIC ranging from 0.21 µM (Scheme
5
0
1
). The compound was bactericidal with cytotoxic profile within acceptable range. Therefore,
a lead optimization programme was initiated with the goal of achieving potent antitubercular
activity.
The program of chemo-transformation initiated with compound 5a. An increase in the length
of alkyl chain with amide linkage intact (5a) have shown improved potency. Another
substitution with Ar = Benzyl, 5b showed similar pharmacological activity. To achieve better
activity, we used phenyl and benzyl group with chloro substitution. In case of 5e and 5f,
improved activity was observed as reported. Similar attempt with the benzyl substitution (5c
and 5d) was disappointing with no further increase in activity. Assuming, chlorine has vital
role to play in the orientation and receptor bindings, 5g and 5h were synthesised but failed to
reflect potentiation.
Close look at SAR revealed that “small changes make big difference”, thus wondering if one
carbon elongation or branching will embark any betterment in inhibition, further set of series
6
a-h, 7a-h and 8a-h were synthesized and tested. In case of branched series 6a-h it was not
surprising to note either equipotent or diminished action. This may owe to the addition of
bulk to the 3D structure of molecules. Only compound 6f has shown slight improved activity.
The attempt of chain elongation, 7a-h disclosed different SAR. Except for dichloro
4

ACCEPTED MANUSCRIPT
compounds 7g and 7h, all showed increased potency. Molecule 7f has emerged as hit with
almost equipotent to isoniazide.
When synthesised branched analogs of 7 series i.e. 8a-h series, on contrary to our
expectations, none of the compound was as promising as 7f. Thus we decided to further
evaluate 7f to compare with standard drug isoniazid (INH).
First we compared 7f with INH for their susceptibilities on 18 clinical isolates (Table-2) of
MTB (M. tuberculosis), out of which 16 were pan-susceptible and 2 were mono-rifampin
resistant isolates. We are happy to report that our compound 7f have been shown almost
equipotent to that of INH. Having seen its potential, we decided to evaluate 7f against 9
multi drug resistant (MDR) and 2 poly-drug resistant MTB strains (Table-3). Gladly,
compound has shown promising activity against almost all the resistant strains. The
compound 7f is now under further evaluation stage, which shall be shortly communicated.
3
. Conclusion:
Keeping a widespread use of future antimycobacterials, we aimed to synthesis a cheaper but
better agent for today’s XDR and MDR tuberculosis. In order to do so, we have zeroed at
pyridinyl-thiadiazole, which gave us really tractable small molecules. The evaluation of the
synthesised series revealed a potent compound 7f which was comparable with Isoniazid
against H Rv. The next step of evaluation surprised us with the effectiveness of 7f against 25
3
7
different isolates. The newer compound has shown promising anti-XDR and anti-MDR
tuberculosis activity. Further attempts to study the toxophore of the compound are on and
communicated short as the outcomes are available.
4
. Experimental:
4
.1. Chemistry
1
H NMR spectra were recorded on a Bruker Avance 500 MHz instrument using TMS as
internal standard; the chemical shifts (δ) are reported in ppm and coupling constants (J) are
given in Hertz. Signal multiplicities are represented by s (singlet), d (doublet), t (triplet), ds
(double singlet), dd (double doublet), m (multiplet), and bs (broad singlet). Mass spectra were
recorded on a Finnigan LCQ mass spectrometer. Elemental analysis was performed on a
Heracus CHN-Rapid Analyser. Analysis indicated by the symbols of the elements of
functions was within ± 0.4% of the theoretical values. The purity of the compounds was
checked on silica gel coated Al plates (Merck).
5

ACCEPTED MANUSCRIPT
4
.1.1. Synthesis of 2-(5-(pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-
(substituted)phenylacetamide 5a-h, 2-(5-(pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-
(substituted)phenylpropanamide 6a-h, 3-(5-(pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-
(substituted)phenylpropanamide 7a-h and 3-(5-(pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-2-
methyl-N-(substituted)phenylpropanamide 8a-h.
To a cool solution of metallic sodium (1 mol) in an absolute ethanol; 5-(pyridin-4-yl)-1,3,4-
thiadiazole-2-thiol (1 mol) (4) was added with stirring, at about 15 °C. The solution was
filtered. The excess of solvent was removed under suction and cold water was added to get a
clear solution. The solution was again filtered to remove suspended particles. Then N-
substituted-chloroalkylamide (1 mol) was added in small portion at room temperature with
stirring, then stirring was continue between 60 to 65 °C for 8 h cooled and extracted with
EtOAc. The EtOAc layer was dried with sodium sulphate and the column purified.
4
.1.1.1. 2-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-phenylacetamide (5a).
1
Yield 76%; mp 187 °C; H NMR (500 MHz, CDCl ): δ 3.83 (s, 2H, CH ), 7.02-7.51 (m, 5H,
3
2
ArH), 7.60-7.63 (dd, 2H, JCH=CH = 1.8, ArH), 8.10 (br, 1H, NH), 8.67-8.70 (dd, 2H, JCH=CH
=
+
1
.8, ArH); MS m/z (%) 329.41 (M , 100); Anal. Calcd. for C H N OS .
1
5
12
4
2
4
.1.1.2. 2-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-benzylacetamide (5b).
1
Yield 68%; mp 189 °C; H NMR (500 MHz, CDCl ): δ 3.87 (s, 2H, CH ), 4.45 (s, 2H, CH ),
3
2
2
7
.01-7.15 (m, 5H, ArH), 7.62-7.65 (dd, 2H, JCH=CH = 1.8, ArH), 8.13 (br, 1H, NH), 8.62-8.65
+
(
dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%) 343.48 (M , 100); Anal. Calcd. for C H N OS .
16
14
4
2
4
.1.1.3. N-(2-Chlorobenzyl)-2-(5-(pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)acetamide (5c).
1
Yield 82%; mp 212 °C; H NMR (500 MHz, CDCl ): δ 3.89 (s, 2H, CH ), 4.48 (s, 2H, CH ),
3
2
2
7
.05-7.17 (m, 4H, ArH), 7.61-7.64 (dd, 2H, JCH=CH = 1.8, ArH), 8.15 (br, 1H, NH), 8.60-8.64
+
(
dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%) 378.88 (M , 100); Anal. Calcd. for C H ClN OS .
16
13
4
2
4
.1.1.4. N-(4-Chlorobenzyl)-2-(5-(pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)acetamide (5d).
1
Yield 68%; mp 208 °C; H NMR (500 MHz, CDCl ): δ 3.84 (s, 2H, CH ), 4.43 (s, 2H, CH ),
3
2
2
7
.03-7.05 (dd, 2H, JCH=CH = 2.4, ArH), 7.12-7.14 (dd, 2H, JCH=CH = 2.4, ArH), 7.63-7.66 (dd,
2
H, JCH=CH = 1.8, ArH), 8.13 (br, 1H, NH), 8.63-8.67 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z
+
(
%) 378.88 (M , 100); Anal. Calcd. for C H ClN OS .
1
6
13
4
2
6

ACCEPTED MANUSCRIPT
4
.1.1.5. 2-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-(2-chlorophenyl)acetamide (5e).
1
Yield 82%; mp 112 °C; H NMR (500 MHz, CDCl ): δ 3.82 (s, 2H, CH ), 6.96-7.53 (m, 4H,
3
2
ArH), 7.64-7.68 (dd, 2H, JCH=CH = 1.8, ArH), 8.17 (br, 1H, NH), 8.68-8.71 (dd, 2H, JCH=CH
=
+
1
.8, ArH); MS m/z (%) 364.90 (M , 100); Anal. Calcd. for C H ClN OS .
1
5
11
4
2
4
.1.1.6. 2-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-(4-chlorophenyl)acetamide (5f).
1
Yield 69%; mp 198 °C; H NMR (500 MHz, CDCl ): δ 3.85 (s, 2H, CH ), 7.24-7.27 (dd, 2H,
3
2
JCH=CH = 2.6, ArH), 7.55-7.58 (dd, 2H, JCH=CH = 2.6, ArH), 7.62-7.67 (dd, 2H, JCH=CH = 1.8,
+
ArH), 8.19 (br, 1H, NH), 8.62-8.67 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%) 364.90 (M ,
1
00); Anal. Calcd. for C H ClN OS .
15 11 4 2
4
.1.1.7. 2-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-(2,6-dichlorophenyl)acetamide (5g).
1
Yield 73%; mp 216 °C; H NMR (500 MHz, CDCl ): δ 3.86 (s, 2H, CH ), 6.94-7.24 (m, 3H,
3
2
ArH), 7.64-7.67 (dd, 2H, JCH=CH = 1.8, ArH), 8.12 (br, 1H, NH), 8.69-8.72 (dd, 2H, JCH=CH
=
+
1
.8, ArH); MS m/z (%) 399.3 (M , 100); Anal. Calcd. for C H C N OS .
1
5
10 l2
4
2
4
.1.1.8. 2-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-(2,4-dichlorophenyl)acetamide (5h).
1
Yield 81%; mp 227 °C; H NMR (500 MHz, CDCl ): δ 3.87 (s, 2H, CH ), 7.12-7.15 (dd, 2H,
3
2
JCH=CH = 2.2, ArH), 7.24 (s, 1H, ArH), 7.51-7.53 (dd, 2H, JCH=CH = 2.2, ArH), 7.64-7.69 (dd,
2
H, JCH=CH = 1.8, ArH), 8.13 (br, 1H, NH), 8.67-8.70 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z
+
(
%) 399.3 (M , 100); Anal. Calcd. for C H C N OS .
1
5
10 l2
4
2
4
.1.1.9. 2-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-phenylpropanamide (6a).
1
Yield 53%; mp 248 °C; H NMR (500 MHz, CDCl ): δ 1.53 (d, 3H, CH ), 3.60-3.64 (q, 1H,
3
3
CH), 7.02-7.51 (m, 5H, ArH), 7.62-7.64 (dd, 2H, JCH=CH = 1.8, ArH), 8.14 (br, 1H, NH),
+
8
.62-8.70 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%) 343.5 (M , 100); Anal. Calcd. for
C H N OS .
16
14
4
2
4
.1.1.10. 2-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-benzylpropanamide (6b).
1
Yield 60%; mp 237 °C; H NMR (500 MHz, CDCl ): δ 1.50 (d, 3H, CH ), 3.61-3.65 (q, 1H,
3
3
CH), 4.45 (s, 2H, CH ), 7.01-7.15 (m, 5H, ArH), 7.61-7.64 (dd, 2H, J
= 1.8, ArH), 8.13
2
CH=CH
+
(
br, 1H, NH), 8.63-8.67 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%) 357.5 (M , 100); Anal.
Calcd. for C H N OS .
1
7
16
4
2
7

ACCEPTED MANUSCRIPT
4
.1.1.11. N-(2-Chlorobenzyl)-2-(5-(pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)propanamide (6c).
1
Yield 68%; mp 227 °C; H NMR (500 MHz, CDCl ): δ 1.52 (d, 3H, CH ), 3.65-3.69 (q, 1H,
3
3
CH), 4.48 (s, 2H, CH ), 7.05-7.17 (m, 4H, ArH), 7.63-7.66 (dd, 2H, J
= 1.8, ArH), 8.16
2
CH=CH
+
(
br, 1H, NH), 8.62-8.66 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%) 392.9 (M , 100); Anal.
Calcd. for C H ClN OS .
1
7
15
4
2
4
.1.1.12. N-(4-Chlorobenzyl)-2-(5-(pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)propanamide (6d).
1
Yield 56%; mp 208 °C; H NMR (500 MHz, CDCl ): δ 1.54 (d, 3H, CH ), 3.63-3.67 (q, 1H,
3
3
CH), 4.43 (s, 2H, CH ), 7.03-7.05 (dd, 2H, J
= 2.4, ArH), 7.12-7.14 (dd, 2H, JCH=CH =
2
CH=CH
2
.4, ArH), 7.64-7.67 (dd, 2H, JCH=CH = 1.8, ArH), 8.12 (br, 1H, NH), 8.65-8.70 (dd, 2H,
+
JCH=CH = 1.8, ArH); MS m/z (%) 392.9 (M , 100); Anal. Calcd. for C H ClN OS .
17
15
4
2
4
.1.1.13. 2-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-(2-chlorophenyl)propanamide (6e).
1
Yield 63%; mp 215 °C; H NMR (500 MHz, CDCl ): δ 1.55 (d, 3H, CH ), 3.63-3.66 (q, 1H,
3
3
CH), 6.96-7.53 (m, 4H, ArH), 7.62-7.67 (dd, 2H, JCH=CH = 1.8, ArH), 8.14 (br, 1H, NH),
+
8
.68-8.73 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%) 378.9 (M , 100); Anal. Calcd. for
C H ClN OS .
16
13
4
2
4
.1.1.14. 2-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-(4-chlorophenyl)propanamide (6f).
1
Yield 84%; mp 235 °C; H NMR (500 MHz, CDCl ): δ 1.52 (d, 3H, CH ), 3.62-3.65 (q, 1H,
3
3
CH),7.24-7.27 (dd, 2H, JCH=CH = 2.6, ArH), 7.55-7.58 (dd, 2H, JCH=CH = 2.6, ArH), 7.65-7.68
(dd, 2H, JCH=CH = 1.8, ArH), 8.10 (br, 1H, NH), 8.67-8.71 (dd, 2H, JCH=CH = 1.8, ArH); MS
+
m/z (%) 378.9 (M , 100); Anal. Calcd. for C H ClN OS .
1
6
13
4
2
4
.1.1.15. 2-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-(2,6-dichlorophenyl)propanamide
(6g).
1
Yield 80%; mp 242 °C; H NMR (500 MHz, CDCl ): δ 1.57 (d, 3H, CH ), 3.63-3.67 (q, 1H,
3
3
CH), 6.94-7.24 (m, 3H, ArH), 7.63-7.66 (dd, 2H, JCH=CH = 1.8, ArH), 8.11 (br, 1H, NH),
+
8
.65-8.68 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%) 413.3 (M , 100); Anal. Calcd. for
C H Cl N OS .
16
12
2
4
2
4
.1.1.16. 2-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-(2,4-dichlorophenyl)propanamide
(6h).
8

ACCEPTED MANUSCRIPT
1
Yield 64%; mp 236 °C; H NMR (500 MHz, CDCl ): δ 1.56 (d, 3H, CH ), 3.60-3.63 (q, 1H,
3
3
CH), 7.12-7.15 (dd, 2H, JCH=CH = 2.2, ArH), 7.24 (s, 1H, ArH), 7.51-7.53 (dd, 2H, JCH=CH
=
2
.2, ArH), 7.60-7.63 (dd, 2H, JCH=CH = 1.8, ArH), 8.10 (br, 1H, NH), 8.63-8.68 (dd, 2H,
+
JCH=CH = 1.8, ArH); MS m/z (%) 413.3 (M , 100); Anal. Calcd. for C H Cl N OS .
16
12
2
4
2
4
.1.1.17 3-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-phenylpropanamide (7a).
1
Yield 68%; mp 203 °C; H NMR (500 MHz, CDCl ): δ 2.63-2.67 (tt, 2H, J
= 2.7,
CH=CH
3
ArH), 3.32-3.36 (tt, 2H, JCH=CH = 2.7, ArH), 7.02-7.51 (m, 5H, ArH), 7.61-7.64 (dd, 2H,
JCH=CH = 1.8, ArH), 8.15 (br, 1H, NH), 8.60-8.76 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%)
+
3
43.4 (M , 100); Anal. Calcd. for C H N OS .
1
6
14
4
2
4
.1.1.18. 3-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-benzylpropanamide (7b).
1
Yield 63%; mp 218°C; H NMR (500 MHz, CDCl ): δ 2.61-2.64 (tt, 2H, J
= 2.7, ArH),
CH=CH
3
3
.31-3.36 (tt, 2H, JCH=CH = 2.7, ArH), 4.45 (s, 2H, CH ), 7.01-7.15 (m, 5H, ArH), 7.62-7.66
2
(dd, 2H, JCH=CH = 1.8, ArH), 8.16 (br, 1H, NH), 8.67-8.73 (dd, 2H, JCH=CH = 1.8, ArH); MS
+
m/z (%) 357.5 (M , 100); Anal. Calcd. for C H N OS .
1
7
16
4
2
4
.1.1.19. N-(2-Chlorobenzyl)-3-(5-(pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)propanamide (7c).
1
Yield 60%; mp 213 °C; H NMR (500 MHz, CDCl ): δ 2.62-2.65 (tt, 2H, J
= 2.7,
CH=CH
3
ArH), 3.30-3.35 (tt, 2H, JCH=CH = 2.7, ArH), 4.48 (s, 2H, CH ), 7.05-7.17 (m, 4H, ArH), 7.62-
2
7
.68 (dd, 2H, JCH=CH = 1.8, ArH), 8.12 (br, 1H, NH), 8.63-8.68 (dd, 2H, JCH=CH = 1.8, ArH);
+
MS m/z (%) 392.9 (M , 100); Anal. Calcd. for C H ClN OS .
1
7
15
4
2
4
.1.1.20. N-(4-Chlorobenzyl)-3-(5-(pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)propanamide (7d).
1
Yield 59%; mp 217°C; H NMR (500 MHz, CDCl ): δ 2.64-2.68 (tt, 2H, J
= 2.7, ArH),
= 2.4,
3
CH=CH
3
.34-3.38 (tt, 2H, JCH=CH = 2.7, ArH),4.43 (s, 2H, CH ), 7.03-7.05 (dd, 2H, J
2 CH=CH
ArH), 7.12-7.14 (dd, 2H, JCH=CH = 2.4, ArH), 7.62-7.69 (dd, 2H, JCH=CH = 1.8, ArH), 8.19 (br,
+
1
H, NH), 8.67-8.70 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%) 392.9 (M , 100); Anal. Calcd.
for C H ClN OS .
1
7
15
4
2
4
.1.1.21. 3-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-(2-chlorophenyl)propanamide (7e).
1
Yield 63%; mp 203°C; H NMR (500 MHz, CDCl ): δ 2.62-2.65 (tt, 2H, J
= 2.7, ArH),
CH=CH
3
3
.33-3.37 (tt, 2H, JCH=CH = 2.7, ArH), 6.96-7.53 (m, 4H, ArH), 7.66-7.73 (dd, 2H, JCH=CH =
9

ACCEPTED MANUSCRIPT
1
.8, ArH), 8.12 (br, 1H, NH), 8.63-8.70 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%) 378.9
+
1
(
M , 100); Anal. Calcd. for C H ClN OS .
16 13 4 2
4
.1.1.22. 3-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-(4-chlorophenyl)propanamide (7f).
1
Yield 64%; mp 211 °C; H NMR (500 MHz, CDCl ): δ 2.62-2.66 (tt, 2H, J
= 2.7,
CH=CH
3
ArH), 3.35-3.38 (tt, 2H, JCH=CH = 2.7, ArH), 7.24-7.27 (dd, 2H, JCH=CH = 2.6, ArH), 7.55-7.58
(dd, 2H, JCH=CH = 2.6, ArH), 7.65-7.69 (dd, 2H, JCH=CH = 1.8, ArH), 8.18 (br, 1H, NH), 8.66-
+
1
8
.70 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%) 378.9 (M , 100); Anal. Calcd. for
C H ClN OS .
16
13
4
2
4
.1.1.23. 3-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-(2,6-dichlorophenyl)propanamide
(7g).
1
Yield 60%; mp 207 °C; H NMR (500 MHz, CDCl ): δ 2.61-2.66 (tt, 2H, J
= 2.7,
CH=CH
3
ArH), 3.32-3.35 (tt, 2H, JCH=CH = 2.7, ArH), 6.94-7.24 (m, 3H, ArH), 7.64-7.69 (dd, 2H,
JCH=CH = 1.8, ArH), 8.12 (br, 1H, NH), 8.65-8.72 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%)
+
1
4
13.3 (M , 100); Anal. Calcd. for C H Cl N OS .
16 12 2 4 2
4
.1.1.24. 3-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-(2,4-dichlorophenyl)propanamide
(7h).
1
Yield 61%; mp 209 °C; H NMR (500 MHz, CDCl ): δ 2.64-2.67 (tt, 2H, J
= 2.7,
CH=CH
3
ArH), 3.30-3.33 (tt, 2H, JCH=CH = 2.7, ArH), 7.12-7.15 (dd, 2H, JCH=CH = 2.2, ArH), 7.24 (s,
H, ArH), 7.51-7.53 (dd, 2H, JCH=CH = 2.2, ArH), 7.60-7.68 (dd, 2H, JCH=CH = 1.8, ArH), 8.17
1
+
1
(
br, 1H, NH), 8.68-8.73 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%) 413.3 (M , 100); Anal.
Calcd. for C H Cl N OS .
1
6
12
2
4
2
4
.1.1.25. 3-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-2-methyl-N-phenylpropanamide (8a).
1
Yield 62%; mp 205 °C; H NMR (500 MHz, CDCl ): δ 1.25 (d, 3H, CH ), 2.88-2.92 (m, 1H,
3
3
CH), 3.21-3.34 (d, 2H, CH ), 7.02-7.51 (m, 5H, ArH), 7.63-7.68 (dd, 2H, J
= 1.8, ArH),
CH=CH
2
+
8
.12 (br, 1H, NH), 8.68-8.77 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%) 357.4 (M , 100);
Anal. Calcd. for C H N OS .
1
7
16
4
2
4
.1.1.26. 3-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-benzyl-2-methylpropanamide (8b).
1
Yield 71%; mp 187 °C; H NMR (500 MHz, CDCl ): δ 1.21 (d, 3H, CH ), 2.81-2.85 (m, 1H,
3
3
CH), 3.20-3.31 (d, 2H, CH ), 4.45 (s, 2H, CH ), 7.01-7.15 (m, 5H, ArH), 7.66-7.75 (dd, 2H,
2
2
1
0

ACCEPTED MANUSCRIPT
JCH=CH = 1.8, ArH), 8.10 (br, 1H, NH), 8.67-8.76 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%)
+
3
71.5 (M , 100); Anal. Calcd. for C H N OS .
1
8
18
4
2
4
.1.1.27. N-(2-Chlorobenzyl)-3-(5-(pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-2-
methylpropanamide (8c).
1
Yield 72%; mp 186 °C; H NMR (500 MHz, CDCl ): δ 1.26 (d, 3H, CH ), 2.84-2.89 (m, 1H,
3
3
CH), 3.21-3.30 (d, 2H, CH ), 4.48 (s, 2H, CH ), 7.05-7.17 (m, 4H, ArH), 7.63-7.69 (dd, 2H,
2
2
JCH=CH = 1.8, ArH), 8.17 (br, 1H, NH), 8.64-8.71 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%)
+
1
4
06.9 (M , 100); Anal. Calcd. for C H ClN OS .
18 17 4 2
4
.1.1.28. N-(4-Chlorobenzyl)-3-(5-(pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-2-
methylpropanamide (8d).
1
Yield 73%; mp 176 °C; H NMR (500 MHz, CDCl ): δ 1.22 (d, 3H, CH ), 2.83-2.88 (m, 1H,
3
3
CH), 3.22-3.31 (d, 2H, CH ), 4.43 (s, 2H, CH ), 7.03-7.05 (dd, 2H, J
= 2.4, ArH), 7.12-
2
2
CH=CH
7
.14 (dd, 2H, JCH=CH = 2.4, ArH), 7.62-7.67 (dd, 2H, JCH=CH = 1.8, ArH), 8.16 (br, 1H, NH),
+
1
8
.63-8.70 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%) 406.9 (M , 100); Anal. Calcd. for
C H ClN OS .
18
17
4
2
4
.1.1.29. 3-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-(2-chlorophenyl)-2-
methylpropanamide (8e).
1
Yield 77%; mp 208 °C; H NMR (500 MHz, CDCl ): δ 1.24 (d, 3H, CH ), 2.84-2.87 (m, 1H,
3
3
CH), 3.23-3.35 (d, 2H, CH ), 6.96-7.53 (m, 4H, ArH), 7.62-7.69 (dd, 2H, J
= 1.8, ArH),
CH=CH
2
+
1
8
.13 (br, 1H, NH), 8.65-8.71 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%) 392.9 (M , 100);
Anal. Calcd. for C H ClN OS .
1
7
15
4
2
4
.1.1.30. 3-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-(4-chlorophenyl)-2-
methylpropanamide (8f).
1
Yield 73%; mp 185 °C; H NMR (500 MHz, CDCl ): δ 1.27 (d, 3H, CH ), 2.82-2.86 (m, 1H,
3
3
CH), 3.24-3.36 (d, 2H, CH ), 7.24-7.27 (dd, 2H, J
= 2.6, ArH), 7.55-7.58 (dd, 2H,
2
CH=CH
JCH=CH = 2.6, ArH), 7.61-7.68 (dd, 2H, JCH=CH = 1.8, ArH), 8.14 (br, 1H, NH), 8.64-8.73 (dd,
+
1
2
H, JCH=CH = 1.8, ArH); MS m/z (%) 392.9 (M , 100); Anal. Calcd. for C H ClN OS .
17 15 4 2
4
.1.1.31. 3-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-(2,6-dichlorophenyl)-2-
methylpropanamide (8g).
1
1

ACCEPTED MANUSCRIPT
1
Yield 71%; mp 174 °C; H NMR (500 MHz, CDCl ): δ 1.20 (d, 3H, CH ), 2.83-2.90 (m, 1H,
3
3
CH), 3.23-3.37 (d, 2H, CH ), 6.94-7.24 (m, 3H, ArH), 7.62-7.68 (dd, 2H, J
= 1.8, ArH),
CH=CH
2
+
1
8
.17 (br, 1H, NH), 8.63-8.75 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%) 427.3 (M , 100);
Anal. Calcd. for C H C N OS .
1
7
14 l2
4
2
4
.1.1.32. 3-(5-(Pyridin-4-yl)-1,3,4-thiadiazol-2-ylthio)-N-(2,4-dichlorophenyl)-2-
methylpropanamide (8h).
1
Yield 78%; mp 180 °C; H NMR (500 MHz, CDCl ): δ 1.23 (d, 3H, CH ), 2.80-2.85 (m, 1H,
3
3
CH), 3.24-3.38 (d, 2H, CH ), 7.12-7.15 (dd, 2H, J
= 2.2, ArH), 7.24 (s, 1H, ArH), 7.51-
2
CH=CH
7
.53 (dd, 2H, JCH=CH = 2.2, ArH), 7.62-7.70 (dd, 2H, JCH=CH = 1.8, ArH), 8.18 (br, 1H, NH),
+
1
8
.61-8.73 (dd, 2H, JCH=CH = 1.8, ArH); MS m/z (%) 427.3 (M , 100); Anal. Calcd. for
C H C N OS .
17
14 l2
4
2
4
4
.2. Antimycobacterial activity
.2.1. Strains and growth conditions
M. tuberculosis H Rv (ATCC, cat. no. 27294), derivative strains and clinical isolates were
37
maintained in Middlebrook 7H9 broth medium supplemented with 0.2% glycerol, 0.05%
Tween 80 and 10% ADS supplement. Culture media were supplemented with hygromycin
−
1
−1
(
50 µg ml ) or kanamycin (20 µg ml ) when required.
4
.2.2. High-throughput cell-based screen
M. bovis BCG was cultured to an OD600 of 0.5–0.6 in complete 7H9 broth medium. In
preparation for 1536-well dispensing, the culture was diluted to an OD600 of 0.01 using
complete 7H9 media. A volume of 4 µl of complete 7H9 media was dispensed into a white,
solid bottom 1536-well plate using a custom Bottle Valve liquid dispenser (GNF). A volume
of 100 nl of test compound in DMSO (1 mM) was then transferred into each assay plates
using a custom 1536 Pintool (GNF). Diluted culture (4 µl) was subsequently added to the
assay plates using a Bottle Valve liquid dispenser (final OD600 in 8 µl is 0.005). The plates
were incubated at 37 °C for 48 h. Growth was assessed by measuring ATP levels using the
BacTiter-Glo Microbial Cell Viability Assay (Promega). Luminescence was measured using
a ViewLux plate reader.
4
.2.3. MIC determination
50
1
2

ACCEPTED MANUSCRIPT
MIC50 were determined as previously described, with slight modifications [17]. Briefly,
compounds dissolved in 90% DMSO were twofold serial-diluted in duplicates and spotted by
mosquito HTS (TTP LabTech) to 384-well clear plates, resulting in 10 dilutions of each
compound. A volume of 50 µl of M. tuberculosis culture (final OD600 of 0.02) was added to
each well, and the assay plates were incubated at 37 °C for 5 days. OD600 values were
recorded using a SpectraMax M2 spectrophotometer, and MIC curves were plotted using
5
0
GraphPad Prism 5 software. Under the assay setting, MIC values, which fall in the linear
5
0
part of the inhibition curve, are more robust and reproducible than MIC . Therefore, only
90
MIC values are reported. Clinical isolates used in drug susceptibility testing were strain
5
0
typed by IS6110 analysis as described [18].
.2.4. Cytotoxicity
4
Cytotoxicity was tested against cell lines HepG2 (ATCC, cat. no. HB-8065) and BHK21
ATCC, cat. no. CCL-10) in 96-well microplates. The cells were seeded at a density of 105
(
cells per well, incubated at 37 °C for 24 h and exposed to twofold serial-diluted compounds
for 3 days. Cell viability was monitored using the Cell Proliferation Kit II (Invitrogen).
4
.2.5. Determination of intracellular ATP levels
The intracellular ATP level was quantified as previously described [19]. Briefly, 25 µl of M.
tuberculosis culture was mixed with an equal volume of freshly prepared BacTiter-Glo
reagent in white 384 flat-bottom plates and incubated in the dark for 5 min. Luminescence
was measured using a Tecan Safire2 plate reader.
4
.2.6. Drug preparation
Unless specified, all the compounds were obtained from Sigma and were prepared in sterile
de-ionized water. The experimental compounds were prepared in dimethyl sulphoxide
(Sigma) for in vitro drug susceptibility testing.
Acknowledgment
We sincerely thank to Dr. Mahendra Shiradkar for all his support in the activity and
characterization.
References:
[
[
1] East African-British Medical Research Councils, Lancet 1, (1972) 1079–1085.
2] Report (no authors listed). Am. Rev. Respir. Dis. 116, (1977) 3–8.
1
3

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[
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3] A. R. Somner, Lancet 1, (1980) 1182–1183.
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[
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Pistorius, R. Krause, M. Bogoshi, G. Churchyard, A. Venter, J. Allen, J. C. Palomino, T. De
Marez, R. P. van Heeswijk, N. Lounis, P. Meyvisch, J. Verbeeck, W. Parys, K. de Beule, K.
Andries, D. F. Mc Neeley, N. Engl. J. Med. 360, (2009) 2397–2405.
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11] C. Kendall, P. Warrener, D. R. VanDevanter, D. R. Sherman, T. M. Arain, M. H.
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4, (2009) 4522-4527.
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[
(
[
13] O. Prakash, M. Kumar, R. Kumar, C. Sharma, K. R. Aneja, Eur. J. Med. Chem. 45,
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14] G. V. Suresh Kumar, Y. Rajendra Prasad, B. P. Mallikarjuna, S. M. Chandrashekar, Eur.
J. Med. Chem. 45, (2010) 5120-5129.
15] D. Zampieri, M. Grazia Mamolo, E. Laurini, C. Zanette, C. Florio, S. Collina, D. Rossi,
O. Azzolina, L. Vio, Eur. J. Med. Chem. 44, (2009) 124-130.
[
1
4

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[
16] Variam Ullas Jeankumar, Janupally Renuka, Peddi Santosh, Vijay Soni, Jonnalagadda
Padma Sridevi, Priyanka Suryadevara, Perumal Yogeeswari, Dharmarajan Sriram, Thiazole–
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[
17] Mahendra Ramesh Shiradkar, Kiran Kumar Murahari, Hanimi Reddy Gangadasu,
Tatikonda Suresh, Chakravarthy Akula Kalyan, Dolly Panchal, Ranjit Kaur, Prashant
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1
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[
18] Nuray Ulusoy Güzeldemirci, Ömer Küçükbasmacı, Synthesis and antimicrobial activity
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[
19] S. P. Rao, S. Alonso, L. Rand, T. Dick, K. Pethe, Proc. Natl Acad. Sci. USA 105, (2008)
1945–11950.
1
1
5

ACCEPTED MANUSCRIPT
Figure-1: Route of synthesis for the compounds 5a-h, 6a-h, 7a-h and 8a-h.
Table 1: Preliminary Structure Activity Relationship of compounds 5a-h, 6a-h, 7a-h and 8a-
h.
Table-2: 7f drug susceptibilities for MTB (pan-susceptible and mono-rifampin resistant)
clinical isolates.
Table-3: 7f drug susceptibilities for MTB (MDR and poly-resistant) clinical isolates.
1
6

ACCEPTED MANUSCRIPT
Figure-1:
Scheme 1
S
H
H
N
O
O
O
N
O
K S
N
Et
H N
2
N N
S
H
0
0
-5 C; H SO
2
4
NH NH H O
KOH; EtOH; CS2
2
2
2
SH
N
EtOH; Reflux
N
3
N
N
2
4
1
Scheme 2
N
4
N
SH
H
S
N
N
O
N
N
Cl
Ar
H
Cl
N
Ar
O
Ar
S
N
S
N
H
N
N
O
H
N
H
8a-h
Ar
H
N
S
Ar
N
S
Cl
Ar
N
Cl
Ar
O
Ar
5a-h
O
N
N
O
O
S
N
H
S
N
N
N
H
N
S
6
7a-h
S
N
O
a-h
0
Experimental condition: NaOEt, H O, 60 C
2
1
7

ACCEPTED MANUSCRIPT
Table 1:
ID
R
--
MIC50
µM)
MBC90
(µM)
CC -
BHK21
CC -
HepG2
(µM)
50
50
(
(µM)
4
0.20±0.09 1.25-2.5
0.18±0.08 1.25-2.5
0.19±0.07 1.25-2.5
9.67±1.45 n.d.
11.72±3.57 n.d.
8.52±1.33 n.d.
6.81±1.08 n.d.
>20
>20
1.48±1.28 5-10.
1.15±1.03 5-10
1.26±1.19 5-10
19.70±3.77 14.7±5.89
15.21±2.65 16.2±8.26
17.65±0.68 11.3±5.67
5
5
5
5
5
5
5
5
6
6
6
6
6
6
6
6
7
7
7
7
7
7
7
7
8
8
8
8
8
8
8
8
a
b
c
d
e
f
g
h
a
b
c
d
e
f
g
h
a
b
c
d
e
f
g
h
a
b
c
d
e
f
-C H5
-CH -C H
5
-CH -2-ClC H
-CH -4-ClC H
- 2-ClC H5
-4-ClC H4
-2,5-Cl C H
-2,4-Cl C H
-C H5
-CH -C H
5
-CH -2-ClC H
-CH -4-ClC H
- 2-ClC H5
-4-ClC H4
-2,5-Cl C H
2 6
-2,4-Cl C H
-C H5
-CH -C H
5
-CH -2-ClC H
-CH -4-ClC H
- 2-ClC H5
-4-ClC H4
-2,5-Cl C H
2 6
-2,4-Cl C H
-C H5
-CH -C H
5
-CH -2-ClC H
-CH -4-ClC H
- 2-ClC H5
-4-ClC H4
-2,5-Cl C H
-2,4-Cl C H
6
2
6
n.d.
>50
>50
>50
n.d.
n.d.
>50
>50
>50
n.d.
>50
>50
>50
>50
>50
n.d.
>50
>50
>50
n.d.
n.d.
>50
>50
>50
n.d.
>50
>50
>50
>50
>50
2
6
4
2
6
4
6
6
n.d.
n.d.
2
6
3
2
6
3
6
2
6
2
6
4
>20
n.d.
2
6
4
1.04±0.01 5-10
0.12±0.46 1.25-2.5
1.19±0.39 5-10
2.45±1.22 5-10
0.61±0.13 2.5-5
0.67±0.24 2.5-5
0.65±0.15 2.5-5
0.63±0.24 2.5-5
0.62±0.17 2.5-5
0.07±0.04 1.25-2.5
0.59±0.11 2.5-5
0.55±0.18 2.5-5
2.26±0.84 5-10.
2.51±1.36 5-10
1.89±0.86 5-10
1.68±0.68 n.d.
2.05±1.06 5-10
6
6
3
2
6
3
6
13.97±0.71 18.7±7.4
>50 >50
15.62±0.81 21.5±6.9
2
6
2
6
4
2
6
4
>50
>50
6
7.26±0.51
12.6±0.84
>50
>50
>50
>50
n.d.
>50
>50
8.21±0.22
10.26±8.4
>50
>50
>50
>50
n.d.
>50
>50
6
3
2
6
3
6
2
6
2
6
4
2
6
4
6
0.22±0.5
1.25-2.5
6
g
h
1.55±0.64 5-10
1.48±0.66 5-10
0.03±0.01 n.d.
>50
>50
n.d.
>50
>50
n.d.
2
6
3
2
6
3
Isoniazid --
The inhibitory activity (MIC ) was determined against M. tuberculosis H Rv. The cidal
5
0
37
activity (MBC ) and cytotoxicity (CC ) were determined after 5 days of exposure to a single
9
0
50
dose of compound. Assays were carried out at least two times. MIC : Minimum Inhibitory
5
0
Concentration 50%; MBC : Minimum Bactericidal Concentration 90%, CC : Cyototoxic
90
50
concentration 50%. n.d.: not determined.
1
8

ACCEPTED MANUSCRIPT
Table-2:
-1
SN
Strain
H Rv
TN675*
TN913
MIC (µgml )
Isoniazid
0.03
0.03
0.03
0.03
0.06
0.03
0.03
0.03
0.03
0.06
0.06
0.03
0.06
0.03
0.19
7f
1
2
3
4
5
6
7
8
9
0.015
0.013
0.013
0.03
0.06
0.06
0.03
0.06
0.06
0.25
0.25
0.06
0.13
0.06
0.25
0.25
0.13
0.06
3
7
TN994*
TN1008
TN1037
TN1040
TN1051
TN1082
TN2351
TN2524
TN3183
TN3979
TN4259
AH9584
BE11677
E8133
1
1
1
1
1
1
1
1
1
0
1
2
3
4
5
6
7
8
0.20
0.08
0.03
W4
Compound 7f and Isoniazid drug susceptibilities were determined on 16 pan-susceptible and
mono-rifampin resistant (asterisk) clinical isolates.
2
1
9

ACCEPTED MANUSCRIPT
Table-3:
-1
SN
1
2
3
4
5
6
7
8
Strain
Drug Resistance
R,S,EM,ET,K.Cl
I,R,S,EM,ET,K
I,S,EM,P
I,R,EM,P
I,R,S,EM,ET
I,R,EM
I,S,EM
I,R
I,R,S,EM,ET,CI
I,R,S,EM
I,R,S,EM,CA
7f MIC (µgml )
0.06
0.06
0.25
0.06
0.06
0.03
0.25
0.03
TN565
TN576
TN702
TN715
TN768
TN772
TN1195
TN1314
TN1618
TN1811
TN2557
9
0.06
0.03
0.13
1
1
0
1
The 7f susceptibilities were also tested on 9 multi-drug resistant (MDR) and 2 poly-resistant
MTB strains. (b) Twenty of the twenty-five sensitive and resistant clinical isolates tested
were previously determined to be genetically distinct by IS6110 genotyping. I, isoniazid; R,
rifampin; S, streptomycin; EM, ethambutol; ET, ethionamide; K, kanamycin; P,
pyrazinamide; Cl, ciprofloxacin; CA, capreomycin.
2
0

ACCEPTED MANUSCRIPT
Linked pyridinyl-thiadiazoles: Design & synthesis as potential candidate for treatment
of XDR and MDR tuberculosis.
Mr. N. S. Mahajan*, Dr. S. C. Dhawale
•
•
•
•
Tractable small molecules are synthesised with easy, inexpensive ROS.
Analoging of newer chemotype, lead to hit 7f.
Reported here antimycobacterial activity of 7f with 25 clinical isolates.
Toxicity profile of 7f is observed minimal.