Comparative Phytochemical and Biological Evaluation of Cassia fistula Stem and Flower with Green Synthesis and Characterization of Zinc Oxide Nanoparticles.

·        Cassia fistula stem and flower are rich sources of bioactive phytochemicals such as flavonoids, phenolic compounds, tannins, alkaloids, and glycosides, which contribute to their medicinal properties. ·        Comparative analysis revealed that both stem and  flower extracts possess significant biological activities, including antioxidant and antimicrobial potential, although their efficacy may vary depending on their phytochemical composition. ·        The green synthesis method successfully produced  zinc oxide nanoparticles (ZnO-NPs) using stem and flower extracts as natural reducing and stabilizing agents, eliminating the need for toxic chemicals. ·        Plant-mediated synthesis proved to be an eco- friendly, cost-effective, sustainable, and simple approach for the preparation of ZnO nanoparticles. ·        Characterization studies using UV–Visible spectroscopy, FTIR, XRD, SEM/TEM, and DLS confirmed the successful formation of stable, crystalline, and well-defined ZnO nanoparticles. ·        The biosynthesized ZnO nanoparticles exhibited enhanced biological activities compared with the corresponding crude plant extracts due to their nanoscale size, high surface area, and synergistic interaction with plant phytochemicals. ·        Comparative evaluation of stem- and flower- mediated ZnO nanoparticles provided valuable information regarding the influence of different phytochemical constituents on nanoparticle synthesis and biological performance. ·        The study demonstrated that Cassia fistula is a  promising medicinal plant for the sustainable production of biologically active ZnO nanoparticles with potential pharmaceutical and biomedical applications.

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