Abstract

The green synthesis of metal nanoparticles by natural products has been recognized as a promising and sustainable technique
in nanobiotechnology, especially for their applications in medicine. The conventional chemical and physical synthesis of
nanoparticles has been associated with toxicity, high energy consumption, and environmental risks, whereas plant-mediated
synthesis has been recognized as an eco-friendly, cost-effective, and biocompatible technique. The natural products used for
synthesizing nanoparticles are leaves, roots, barks, fruits, seeds, latex, and other parts of plants, which contain bioactive molecules
such as flavonoids, phenolic compounds, terpenoids, alkaloids, proteins, and polysaccharides that serve as reducing, capping,
and stabilizing agents for nanoparticles. Among various metal nanoparticles, silver nanoparticles have been recognized for their
excellent antimicrobial, antifungal, antiviral, antioxidant, anti-inflammatory, and anticancer activities. The excellent biological
activities of nanoparticles synthesized by natural products may be attributed to their nanoscale dimensions, high surface area￾to-volume ratio, generation of reactive oxygen species, and interaction with cell membranes, proteins, and DNA. Apart from
their applications in medicine, plant-mediated metal nanoparticles have been recognized for their applications in diagnostics,
biosensors, drug delivery systems, wound healing, catalytic degradation of pollutants, and tissue engineering. The present review
article discusses the role of natural products in the synthesis of nanoparticles, reduction mechanisms, characterization, and
their applications in medicine. The critical factors affecting nanoparticles, including size, shape, stability, and their biological
activities, have also been discussed. The green nanotechnology technique has been recognized as a sustainable and innovative
technique for the development of next-generation nanoparticles with excellent applications in medicine.