Retrospective analysis of the key molecules involved in the green synthesis of nanoparticles.

Emerging nanotechnology leads to success in synthesizing and applying nanoparticles (NPs) using the green-chemistry approach. NPs synthesized using naturally derived materials are a potential alternative to chemical and physical methods because they are simple, cost-effective, eco-friendly, and lower the possibility of hazardous residues being released into the environment. Furthermore, NPs synthesized using the green synthesis approach are stable and biocompatible. However, because natural extracts contain a diverse spectrum of bioactive components, it is difficult to pinpoint the specific component involved in NP formation. Furthermore, the bioactive component contained in the extract changes based on a number of environmental factors; therefore, several studies began with the synthesis of NPs using a pure compound isolated from diverse natural sources. Hence, the present review paper makes an effort to retrospectively analyze the key compounds of the extracts which are responsible for the synthesis of the NPs. The analysis was carried out based on the physicochemical characteristics and biological activities of NPs synthesized from either the extract or the pure compounds. These pure-compound-based NPs were studied for their antimicrobial, antibiofilm, anti-inflammatory, anticancer, and antioxidant properties. In addition, the present review also describes progress in the study of pure compound-based numerous biological activities and the underlying mechanisms of action.