Antibacterial, antioxidant, and anticancer activities of green synthesized silver nanoparticles using aqueous extract of Justicia brandegeana
Noor M. Alassadi, Ghaida'a J. Al-Ghizzawi, Ahmed M. Amshawee, Radwan Ali
Abstract
Silver nanoparticles (Ag NPs) synthesized through the green approach using plant extracts are considered an attractive alternative to standard methods since it is eco-friendly and inexpensive. In this study, Justicia brandegeana was used for the first time as a biogenic source to synthesize silver nanoparticles. The Justicia brandegeana aqueous extract (Jus-w) was used as a natural reducing and capping agent for in situ synthesis of AgNPs (Jus-w@Ag NPs). The successful biosynthesis was initially indicated by a color change, further confirmed by UV-Visible spectroscopy that recorded the maximum absorption at 440 nm. FTIR analysis revealed that proteins and phenolic compounds played a key role in the synthesis and stabilization of Ag NPs. The as-synthesized nanoparticles exhibited a face-centered cubic structure, with an average size of 55.6 nm, well-dispersed without agglomeration, and showed high stability with a zeta potential of −56.9 mV, as confirmed by XRD, FESEM, and EDX analyses. Moreover, GC–MS analysis of the plant extract revealed different phytochemicals responsible for the reduction and capping of silver ions. The antibacterial assessment showed strong inhibition, particularly against Staphylococcus aureus and Shigella flexneri , with inhibition zones reaching 16.2 mm. Furthermore, the nanoparticles displayed significant antioxidant activity by scavenging DPPH free radicals. Their cytotoxicity and anticancer activity were confirmed by MTT assay against SiHa and MCF-7 cancer cell lines, showing dose-dependent effects with an IC₅₀ of 52.9 μg/ml for SiHa and 97.07 μg/ml for MCF-7, thereby demonstrating selective toxicity towards cancer cells. • Green synthesis: AgNPs prepared using Justicia brandegeana aqueous extract. • Characterization: AgNPs (≈55 nm) showed FCC structure and high stability (−56.9 mV). • GC–MS : Phenolic, alcoholic, and carbohydrate compounds acted as Ag⁺ reducing agents. • Antibacterial: Strong inhibition against S. aureus and S. flexneri (16.2 mm). • Anticancer: AgNPs showed selective cytotoxicity toward SiHa and MCF-7 cell lines.