Caesalpinia crista Seeds Mediated Green Synthesis of Zinc Oxide Nanoparticles for Antibacterial, Antioxidant, and Anticancer Activities

In the present study, we attempted a simple, quick, and green method to synthesize ZnO NPs using aqueous seed extract of Caesalpinia crista. The green synthesized ZnO NPs were characterized using different techniques which included UV-Vis spectroscopy, FT-IR, zeta potential, XRD, SAED, and TEM analyses. The synthesis of ZnO NPs was confirmed by its characteristic peak at 380 nm by UV-Vis spectra. XRD and SAED confirmed the crystalline nature, while TEM revealed the size in the range 20-44 nm and average size was 34.67 nm and shape was irregular. FTIR confirmed functional groups like alcohol or phenol, carboxylic acid, ketones, amines, aromatic amines, aliphatic amines, alkyl halides, and alkynes in C. crista seed extract which acted as reducing and stabilizing agent and aided in formation of ZnO NPs. The biosynthesized ZnO NPs showed antimicrobial activity against 14 microorganisms; dose dependent antioxidant activity in terms of DPPH, SO, and ABTS radical scavenging activity; and cytotoxicity against HeLa, MCF-7, and normal fibroblast cell lines. The ZnO NPs showed three biological activities, viz. antimicrobial, antioxidant, and cytotoxic effect. The green synthesized C. crista seed mediated ZnO NPs can be further exploited as a potential candidate for antibacterial, antioxidant, and anticancer agent. Graphical abstract Highlights • Zinc oxide NPs were synthesized using Caesalpinia crista aqueous seed extract • Characterization was done by spectroscopic techniques like UV-Vis, zeta, FTIR, XRD, SAED, and TEM analysis • ZnO NPs were 34.67 nm in size and irregular in shape • Antimicrobial activity was done against 14 pathogenic microorganisms; antifungal activity more than antibacterial activity • Dose dependent antioxidant activity was envisaged in DPPH, SO, and ABTS radical scavenging activity • Cytotoxic activity evaluated by MTT assay against HeLa, MCF-7, and fibroblast normal cell lines