Quinoline Derivatives as Promising Scaffolds for Antitubercular Activity:
A Comprehensive Review
Authors: Owais Mohammad , Kumar Arun , Hasan Syed Misbahul , Singh Kuldeep , Azad Iqbal , Hussain Arshad , Suvaiv  , Akil Mohd 
Published: January 2024

Background:
Heterocyclic compounds and their derivatives play a significant role in the
design and development of novel quinoline drugs. Among the various pharmacologically active heterocyclic
compounds, quinolines stand out as the most significant rings due to their broad pharmacological
roles, specifically antitubercular activity, and their presence in plant-based compounds.
Quinoline is also known as benzpyridine, benzopyridine, and 1-azanaphthalene. It has a benzene
ring fused with a pyridine ring, and both rings share two carbon atoms. The importance of quinoline
lies in its incorporation as a key component in various natural compounds found in medicinal plant
families like Fumariaceae, Berberidaceae, Rutaceae, Papavaraceae, and others.

Objective:
This article is expected to have a significant impact on the advancement of effective antitubercular
drugs. Through harnessing the potent activity of quinoline derivatives, the research aims
to make valuable contributions to combating tuberculosis more efficiently and ultimately reducing
the global burden of this infectious disease.

Methods:
Numerous nitrogen-containing heterocyclic compounds exhibit significant potential as
antitubercular agents. These chemicals have fused aromatic nitrogen-heterocyclic nuclei that can
change the number of electrons they have, which can change their chemical, physical, and biological
properties. This versatility comes from their ability to bind with the receptors in multiple modes, a
critical aspect of drug pharmacological screening. Among these compounds, quinoline stands out as
it incorporates a stable fusion of a benzene ring with a pyridine nucleus. Quinolines have demonstrated
a diverse range of pharmacological activities, including but not limited to anti-tubercular,
anti-tumor, anticoagulant, anti-inflammatory, antioxidant, antiviral, antimalarial, anti-HIV, and antimicrobial
effects.

Results:
Some molecules, such as lone-paired nitrogen species, include pyrrole, pyrazole, and quinoline.
These molecules contain nitrogen and take part in metabolic reactions with other molecules
inside the cell. However, an excessive accumulation of reactive nitrogen species can lead to cytotoxicity,
resulting in damage to essential biological macromolecules. Among these compounds, quinoline
stands out as the oldest and most effective one, exhibiting a wide range of significant properties
such as antitubercular, antimicrobial, anti-inflammatory, antioxidant, analgesic, and anticonvulsant
activities. Notably, naturally occurring quinoline compounds, such as quinine, have proven to be
potent antimalarial drugs.

Conclusion:
This review highlights quinoline derivatives' antitubercular potential, emphasizing recent
research advancements. Utilizing IC50 values, the study emphasizes the efficacy of various
quinoline substitutions, hybrids, and electron-withdrawing groups against MTB H37Rv. Continued
research is essential for developing potent, low-toxicity quinoline derivatives to combat tuberculosis.