Simple and cost-effective approach to synthesis of iron magnesium oxide nanoparticles using Alstonia scholaris and Polyalthia longifolia leaves extracts and their antimicrobial, antioxidant and larvicidal activities

A provident, cost-effective, and environmentally benign plant-mediated approach is adopted for the synthesis of Fe2MgO4 nanoparticles (NPs), using Alstonia scholaris and Polyalthia longifolia leaves’ extracts. The method results in NPs with cubic crystal structure having particle size in range of 8.14–13.4 nm as confirmed by UV–Vis, FTIR, XRD and AFM. The prepared NPs are assessed for their antibacterial, antioxidant and larvicidal activities. Both NPs are found active against gram-positive (Bacillus subtilis, Staphylococcus aureus) and gram-negative bacteria (Pseudomonas aeruginosa, Salmonella typhimurium, and Escherichia coli) obeying the order: NPs A. scholaris > NPs P. longifolia > A. scholaris extract > P. longifolia extract. Similar order is observed for the larvicidal activity against Aedes albopictus larvae; both NPs showed excellent activity with LD50 of 5-10 μg/ml which is much less than the simple plant extracts. Antioxidant potential of NPs is also evaluated using DPPH free radical scavenging and phospho-molybdenum assays and in both cases, NPs of A. scholaris perform better than the control, P. longifolia-based NPs and plant extracts. Hence, the prepared NPs can be potentially applied as antimicrobial and larvicidal agents, as well as for food packaging and medicinal applications.