Tuberculosis (TB) remains a significant global health threat, especially with the emergence of drug-resistant strains. In this study, we aimed to address the pressing need for novel antitubercular agents targeting multidrug- resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB). The quinoxaline nucleus was selected for its unique mechanism of binding with nucleic acid residues and lower reported toxicity. Seven quinoxaline derivatives were synthesized through eight synthetic schemes and screened for antimycobacterial activity against Mycobacterium tuberculosis using the microplate Alamar Blue Assay (MABA) method. Standard strains and concentrations were utilized for comparison: Pyrazinamide (3.125µg/mL), Ciprofloxacin (3.125µg/mL), and Streptomycin (6.25µg/mL). Our results indicate that all synthesized compounds, including derivatives of Histidine, Glutamic Acid, Glycine, Valine, Alanine, Aspartic Acid, and Cysteine, exhibited potent antimycobacterial activity at concentrations as low as 0.8µg/mL, surpassing the efficacy of standard drugs. Particularly, synthetic derivatives of ofloxacin demonstrated significant inhibition against drug-resistant Mycobacterium tuberculosis, highlighting their potential as promising candidates for further investigation. This study underscores the importance of exploring novel chemical entities, such as ofloxacin derivatives with amino acids, to combat the escalating threat of drug- resistant tuberculosis. Further research in this direction holds promise for the development of more effective treatments against virulent TB strains.

1. Dr. M. Geethavani, M. Pharm., PhD
Professor & HOD
Department of pharmaceutical Chemistry
BALAJI COLLEGE PHARMACY (BALA)
Sanapa Road, Rudrampeta bypass Anantapuramu.
Anantapur District, Andhra Pradesh State, INDIA - 515001
Research work

2.  Contents
 Title
 Introduction
 Literacture review
 Aim and objectives
 Drug profile
 Methodology
 Observation , Results and Conclusion
 References

3. Introduction:
 After the discovery of the first fluoroquinolone, norfloxacin
in1980 as an antibacterial agent with potent and broad
spectrum activity, several new members of this family have
emerged with enhanced activity against Gram positive and
anaerobic bacteria with improved pharmacokinetic profile.
 Much has been learned about how molecular modifications
of the core quinolone structure affect the antibacterial profile.
 The structure–activity relationship of quinolones has been the
subject of extensive review. For most of the current agents,
hydrogen at position 2, a carboxyl group at position 3 and a
keto group at position 4 in the bicyclic ring cannot be
changed without a significant loss of activity.
 Furthermore it appears that a cyclopropyl group is optimal at
C-1. Ofloxacin is an antibiotic useful for the treatment of a
number of bacterial infections.

4. Author
Conclusion
Gisela C.Muscia et al The multi component syntheses of 2,4-di-
aryl-quinolines and analogous polycyclic
derivatives as anti-tuberculosis agents.
Dr.D.Sriram et al 1-cyclopropyl-6-fluoro-8-methoxy-1,4-
dihydro-4-oxo-7[[N4-[30-[(4,6-
dimethylpyrimidin-2-
yl)benzenesulfonamido-4-yl]imino-10-(5-
fluoroisatinyl)]methyl]-3-methyl N1-
piperazinyl]-3-quinoline carboxylic acid
emerged as the most potent broad-
spectrum chemotherapeutic agent active
against HIV (EC50: 12.1 mg/ml), and
Mycobacterium tuberculosis (MIC: 1.22
mg/ml).
Martin et al. synthesized binuclear analogues with the
–CONH– bridge connecting the pyrazine
and benzene rings with anti-mycobacterial
activity.
Farzana et al synthesized triazolo derivatives and
evaluate for its anti-TB activity. Literature
review suggests that 4-amino-5-(pyridin-
4-yl)-4H-1, 2, 4-triazole-3-thiol can show
anti TB activity.

5. Aim :
To establish the methods of synthesis for the proposed derivatives
.
Objectives :
• To synthesize some novel ofloxacin derivatives by microwave
oven.
• To confirm the structure of the synthesized ofloxacin by spectral
analysis.
• To evaluate the proposed derivatives for their anti-tubercular
activities.
• To explore possible novel synthetic derivatives of ofloxacin using
potent antimycobacterial pharmacophore such as carboxamide.
• To characterize the structures of new compounds with physical
and spectral data.
• To evaluate antitubercular activity of synthesised compounds

6.  With reference to the need research on antimicrobials for drug resistant
pathogens, the investigation was initiated to synthesize new chemical
entity as a hit for virulent pathogens like Mycobacterium tuberculosis.
 In search of new synthetic molecules it was observed that they are
developing resistance against virulent pathogens.
 In accordance to view on obtaining less toxic and less resistant synthetic
molecules and reference to the high lipophillic scaffold of Ofloxacin
reported in the literature, the present scheme was designed to obtain
amide pharmacophore derivatives of Ofloxacin, in which it acts as a cell
wall/membrane permeability enhance for the selected pharmacophore.
 The present work is a part of this worldwide efforts to develop better
Fluoroquinolones than the available ones with respect to activity or
toxicity or resistance or all of these.

7. Principles Of Microwave Heating
 1.Dipole interaction
Polar ends of a molecule tend to align themselves
and oscillate in step with the oscillating electrical
field of the microwaves. Collisions and friction
between the moving molecules result in heating.
 2. Ionic conduction
It results if there are free ions or ionic species
present in the substance being heated. The electric
field generates ionic motion as the molecules try to
orient themselves to the rapidly changing field.
This causes the instantaneous super heating

8. Advantages
 Uniform heating occurs throughout the material
 Process speed is increased
 High efficiency of heating
 Reduction in unwanted side reaction
 Purity in final product Improve reproducibility
Environmental heat loss can be avoided

9. • Drug profile
OFLOXACIN STRUCTURE:
• Nomenclature : 9-fluoro-3-methyl-10-(4-methylpiperazin-
1yl)-7-oxo-3,7-
dihyro-2H-[1,4]oxazino[2,3,4-ij]quinoline-
6-carboxylic acid
• Molecular weight : 361.368 g/mole.
• Molecular formula : C18H20FN3O4.
• Solubility : Methanol, chloroform.
• Properties:
• Colour : white ,colour less needles from ethanol.
• Melting point : 250-257ºC
• Log P : -0.39
N
O
F
N
O
OH
O
N

10. Literature survey
Chemical synthesis and Purification
Characterization of compounds.
Screening for anti tubercular activity
Development of Structure activity relationship.
Make recommendation for further research.
Step 1
Step 2
Step 3

11. 24-02-2024
Dept. of Pharmaceutical Chemistry 11

12. Ofloxacin
(0.01 mole)
Ofloxacin was treated with Thionyl chloride to get
ofloxacin chloride. Ofloxacinchloride was treated
with diff.amino acids which includes Alanine,
Histidine, Cystine, Glycine, Glutamic acid ,valine
to obtain respective carboxamide derivatives.
Subjected for microwave
irradiation(20seconds) and
subjected for vacuum
filtration.
Reaction is to
be monitored
by TLC
The final product is
tobe subjected to
purification process

13. Scheme:
N
F
O
OH
O
O
N
N
(E)
N
F
O O
O
N
N
(E)
Cl
S
O
C
l
2
N
F
O O
O
N
(E)
N
F
O O
O
N
N
(E)
H
N
(S)
O
O
C
y
st
in
e
N
F
O O
O
N
N
(Z)
Alanine
H
N (S)
HN N
O
HO
HN
(S)
O
OH
Histidine
NH3
Ch
lo
rin
at
ion
N
F
O O
O
N
N
H2N (S)
O
HO
O
HO
Glutamic Acid
N
F
N
N
O
O
H2N
(S)
O
OH
O
Valine
N
O
N
F
H
N
O O
N
O
HO
N
O
N
F
N
O O
H2N
(S)
O
OH
O
HO
G
l
y
c
i
n
e
Microwa
ve
Radiation
-20Sec
M
i
c
r
o
w
a
v
e
R
a
d
i
a
t
i
o
n
-
2
0
S
e
c
Microwave
Radiation -20Sec
M
i
c
r
o
w
a
v
e
R
a
d
i
a
t
i
o
n
-
2
0
S
e
c
Microwave
Radiation -20Sec
Microwave
Radiation -20Sec
M
icrowave
Radiation
-20Sec
A
s
p
a
r
t
i
c
A
c
i
d
N

14. IR: 3405.04 (O-H stretching ), 3133.58 (N-H stretching ), 1709.06 (C=O stretching ), 1295.27 (C-N stretching), 1126.18 (C-O
stretching ), 1050.72 (C-F stretching ).
Ofloxacin Aspartic acid

15. 1HNMR : 6.68-7.90 (2H Fluroquinolone, 1H (4.5), 3H alkyl, ( 5.5) ( oxazine), 4H(
2.27-3.45) (Piperazine), 2H ,2.6 (Methylene), 3H( 2.85) methyl, 1H ( sec.amine)
Ofloxacin aspartic acid

16. Ofloxacin Aspartic acid

17. IR : 3413.72[O-H stretching], 3040.88[N-H stretching], 1714.89[C=O
stretching], 1290.84[C-N stretching], 959.06[C-O stretching],798.16[C-F
stretching].
Ofloxacin Valine

18. NMR:1H [pyridinone 8.418], 1H[Benzene-7.266], 3H[Morpholine- 3.280 -
4.277], C=O[Aliphatic-3.52], 1H[Aliphatic- 2.258] 5H [Piperazine 2.650-3.529]
1H [Piridinone 2.144], Aliphatic morpholine [1.260]Aliphatic 6H, 2CH3 Alkyl
[1.260].
Ofloxacin Valine

19. Ofloxacin Valine
M+1: 360.1

21. Standard Drug Photograph

23. Conclusion:
The synthetic derivatives of ofloxacin exhibited potent
Antimycobacterial activity against Mycobacterium tuberculosis
whilst the activity towards virulent pathogen was good.
 All compounds Histidine, Alanine, Valine, Aspartic acid, Glycine,
Cysteine,
Glutamic acid derivatives bearing ofloxacin carboxamide
exhibited considerable inhibition against drug resistant
Mycobacterium tuberculosis showed high potent activity when
compared to standard drug Streptomycin, pyrazinamide,
ciprofloxacin.
 Further research can be carried out on ofloxacin with amino
acids.

24. 24-02-2024
Dept. of Pharmaceutical Chemistry 24
1. Salah, S. A. (2003). Synthesis and biological evaluation of
tetra cyclic fluoroquinalones as antibacterial and anticancer
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2. Akhiles Roy A.R.(1995).Synthesis and biological evaluation of
some substituted fluoroquinalones. Vol.74, pp. 458-92
3. Asif Hussain PhD, S. A. (2003). Synthesis and biological
evaluation of tetra cyclic fluoroquinalones as antibacterial and
anticancer agents. Vol. 62. pp.293-97.
4. Neu (2002) Symposium on fluoroquinalones [Journal]. - [S.l.]
: the American journal of medicine. Vol. 91. pp. 564
5. Hadi Adibi (2007)Synthesis of 7-substituted fluoroquinalones
derivatives containing triazolidine [Journal]. Vol. 34. pp. 221-23
6. Mohofad Asif (2012)A antimicrobial cancer and anti microbial
activity of tetrafluoroquinalones compounds [Journal]. - [S.l.] :
the American journal of medicine, Vol. 27. pp. 214-45
References

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Dept. of Pharmaceutical Chemistry 25