Background: Isatin (IST) is a crucial pharmacologically active compound, chemically known as indole-
1H-2,3-dione. Development of different IST based analogues acquired significant awareness because of its
pronounced therapeutic importance such as analgesic, anticancer, anti-inflammatory, antitubercular, antimicrobial,
antifungal, antiviral (effective against SARS coronavirus 3C protease) and many other activities, and represents
an important class of heterocyclic compounds that can be used as a precursor for the synthesis of many useful
Objective: Previously, many articles were reported on IST synthesis and its different pharmacological activities
but herein, we mentioned 59 different synthesis schemes of several IST derivatives/hybrids derived from the substitution
of the nitrogen, aromatic ring, the second and third position of IST along with most potent molecule
among each of synthesized libraries with their structural activity relationship (SAR). Using these standardized
approaches, several biologically important compounds were developed like sunitinib, nintedanib, indirubin, etc
and several studies have been carried out nowadays to develop newer compounds having fewer side effects and
also overcome the problem of resistance.
Conclusion: This report critically reviews the different strategies for the designs and synthesis of several IST
based compounds having different biological activities with SAR, which can favour further investigation and
modification for the development of new and more potent entities.