Exploration of Schiff Bases: Structures, Syntheses, and Biological Activities

Schiff bases are organic compounds that were first discovered in 1864 by German chemist Hugo Schiff. These bases result from a condensation reaction between a primary amine and a carbonyl compound, usually an aldehyde or a ketone. This reaction eliminates a water molecule and forms an imine group (-C=N-), the characteristic feature of Schiff bases. These bases are widely studied for their simple synthesis, structural diversity, and numerous applications in pharmacology. This review discusses their general structures and methods of synthesis. Schiff bases can be classified according to their structure (aliphatic or aromatic), denticity, and symmetry. Schiff bases have the ability to coordinate with metal ions such as copper (Cu2+), zinc (Zn2+), cobalt (Co2+), or nickel (Ni2+), allowing the formation of stable metal complexes, which enhances their biological properties. At the biological level, Schiff bases exhibit a wide range of activities due to their imine group. These include antibacterial, antifungal, antiviral, antitubercular, anti-inflammatory, antioxidant, anticancer, and other activities. This biological activity can be enhanced when Schiff bases complex with transition metals. In silico approaches play a crucial role in evaluating the therapeutic potential of Schiff bases and their complexes. These methods help predict their pharmacokinetic properties and binding affinity, thereby facilitating the rational design of more potent and selective therapeutic agents.