Biological applications of Schiff bases: An overview

Schiff bases are the compounds containing the azomethine group (-HC=N-). They are formed by the condensation of ketones or aldehydes with a primary amine. Formation of Schiff base generally takes place under acid/base catalysis or with heat. The common Schiff bases are crystalline solids, which are basic but at least some form insoluble salts with strong acids. Schiff bases are used as intermediates for the synthesis of amino acids or as ligands for the preparation of metal complexes having a series of different structures. The electrophilic carbon and nucleophilic nitrogen in the C=N imine bond provide excellent binding opportunities with different nucleophiles and electrophiles thereby inhibiting targeted diseases, enzymes or DNA replication. These Schiff bases are synthesized from various aldehydes and amines under stirring conditions, catalyst-free, reflux conditions, microwave irradiation and ultrasonic conditions. These compounds serve a wide range of applications in pharmaceutical industries as well as chemical industries. There are a series of biological activities exhibited by these compounds which include antimicrobial, anti-inflammatory, antiviral and antioxidant activities. Apart from exhibiting medicinal properties, Schiff base compounds play an important role as ligands in coordination chemistry. Thus, Schiff bases and their derivatives may be further used for enormous biological applications with potent effects.