Mineral Composition, and Green Synthesis of Metallic Nanoparticles from Justicia carnea with Antioxidant and Antimicrobial Activities

Justicia carnea is a medicinal plant widely used in traditional medicine due to its nutritional value and therapeutic properties. Despite its ethnomedicinal relevance, comprehensive evaluation of its phytochemical composition, biological activities, and potential application in green nanotechnology remains limited. This study aimed to investigate the phytochemical profile, proximate and mineral composition, antioxidant and antimicrobial activities, and the potential of J. carnea extract for the green synthesis of metallic nanoparticles. Qualitative phytochemical screening was performed to identify bioactive constituents in J. carnea extract. Proximate and mineral analyses were conducted using standard analytical procedures. Antioxidant activities were evaluated using DPPH radical scavenging, ferric reducing antioxidant power (FRAP), nitric oxide scavenging, lipid peroxidation inhibition, and Fe²⁺ chelation assays. Antimicrobial activity was assessed against selected bacterial (Xanthomonas axonopodis, Salmonella typhi, and Pseudomonas aeruginosa) and fungal (Fusarium oxysporum and Aspergillus flavus) strains. Green synthesis of silver (AgNPs), zinc (ZnNPs), and copper (CuNPs) nanoparticles was carried out using the plant extract, and nanoparticle formation was confirmed by UV–visible spectroscopy. Phytochemical analysis revealed the presence of saponins, phenols, tannins, terpenoids, alkaloids, and flavonoids. Proximate analysis showed appreciable levels of carbohydrates, crude fiber, protein, and crude fat, while mineral analysis indicated high concentrations of potassium, calcium, iron, and zinc. The extract exhibited strong antioxidant activity across all assays, reflecting its rich phenolic and flavonoid content. Moderate antibacterial and antifungal activities were observed against the tested microorganisms. UV–visible spectroscopic analysis confirmed the successful synthesis of AgNPs, ZnNPs, and CuNPs, with AgNPs showing higher absorbance, suggesting superior stability and yield. The findings demonstrate that Justicia carnea possesses significant nutritional and pharmacological properties and serves as an effective bio-resource for the eco-friendly synthesis of metallic nanoparticles. Its strong antioxidant and antimicrobial activities, combined with its nanotechnological potential, support its application in pharmaceutical, biomedical, and nutraceutical development.