Synthesis and Antioxidant Activities of Schiff Bases and Their Complexes: An Updated Review

Abstract

Schiff bases are chemical compounds formed from the condensation reaction of aldehydes or ketones with amines. These compounds are majorly used in industries and also have significant biological activities, including antioxidant, antibacterial, antifungal, antiviral, antitumor, and anti-inflammatory. The majority of these compounds show excellent catalytic activities. Schiff bases are considered to be the most versatile ligands as they form complexes with the metal atoms. They are called privileged ligands because these compounds can be synthesized simply by condensation. The complexes of copper, zinc, and cadmium are the essential metallic complexes of these compounds. Schiff bases and its metallic complexes are instrumental in scavenging the free radicals and thus protect living bodies from the adverse effects of these radicals. Due to the recent exhaustive study on Schiff bases, it becomes an independent filed of research in chemistry. These compounds are widely investigated; however, the antioxidant properties of these compounds needs further investigation. In this review, we investigate various synthesis mechanisms of Schiff bases and their essential antioxidant activities. We also explore the metallic complexes of some most essential Schiff bases and their effects on living cells. The present study will be valuable to provide a foundation for antioxidant characterization of Schiff bases and for future studies on Schiff bases to synthesize high-quality antioxidant compounds.