Antimicrobial and mosquito larvicidal activity of iron oxide nanoparticles phytosynthesized from the medicinal plant Andrographis serpyllifolia

Nanoparticles (NPs) play a significant role in protecting human and environmental health. Worldwide, research is focused on developing new pharmaceuticals and environmentally safe materials. The current research reports the phytosynthesis of NPs from iron oxide (Fe2O3) mediated through ethanolic extracts of Andrographis serpyllifolia leaf (ASL) and their antimicrobial (bacteria and fungi) and mosquito (Culex quinquefasciatus) larvicidal activity. ASL was treated with aqueous iron chloride solution to turn into synthesized Fe2O3-NPs. The biosynthesized ASL·Fe2O3-NPs were characterized with spectroscopic, electron microscopic and X-ray analyses. The synthesized ASL·Fe2O3-NPs were characteristically showed triclinic crystal shape in SEM. The purity of synthesized Fe2O3 nanoparticles was confirmed by FT-IR analysis. Out of twelve different selective pathogens (4 G+ve bacteria, 4 G-ve bacteria and 4 fungal species) tested with ASL·Fe2O3-NPs, a maximum of 20.3 mm inhibition zone against Staphylococcus aureus among G+ve bacteria and 19.1 mm inhibition zone against Pseudomonas aeruginosa among G-ve bacteria was observed; while it was 16.9 mm against fungi (Aspergillus niger) at a test concentration of 100 µL. The exposure of 4th instar larvae for 48 h to ASL·Fe2O3-NPs exhibited a significant LC50 value at 12.80 ppm. The study findings reveal that the Fe2O3‑NPs synthesized using A. serpyllifolia leaf extract could be a potential source for antibacterial, antifungal and mosquito larvicidal activities.