In vitro antioxidant, anti-inflammatory, antibacterial, and cytotoxic effect of Sida cordifolia: synthesized metal nanoparticles

Metal oxide nanoparticles (MNPs) of Manganese oxide (Mn3O4) and zinc oxide (ZnO) were synthesized using methanolic Sida cordifolia root extract (SCE) and characterized using UV–Visible Spectroscopy, FT-IR, SEM and XRD followed by antimicrobial studies. Mn3O4 NPs and ZnO NPs shown absorbance at 275, 325 and 354 nm respectively which confirms the formation of nanoparticles. In FTIR, peaks at 620 and 515 cm−1 correspond to Mn–O stretching of octahedral and tetrahedral sites respectively while peaks at 680.28 and 470.74 cm−1 confirms ZnO formation. XRD confirms the crystalline structure, tetragonal hausmannite for Mn3O4 NPs and hexagonal wurtzite for ZnO NPs. SEM revealed that Mn3O4 NPs and ZnO NPs exhibited reduced agglomeration, with an average size of 40.5 and 13.7 nm respectively. In antibacterial studies, at 100 µg/mL, Mn3O4 NPs inhibited E. coli (11 ± 0.856 mm) and S. aureus (16 ± 1.365 mm), while ZnO NPs showed 18 ± 0.517 and 9 ± 1.583 mm inhibition respectively. The following in vitro assays carried out: DPPH assay, IC50 values of extract, Mn3O4 NPs and ZnO NPs were 37.05 μg/mL, 5.77 μg/mL and 9.10 μg/mL and in ABTS assay, IC50 values were found to be 37.05 μg/mL, 13.09 μg/mL and 18.09 μg/mL respectively. Cholinesterase inhibition showed IC₅₀ values of 35.84, 28.63, and 17.70 µg/mL for SCE, Mn3O4, and ZnO NPs respectively indicating superior activity of ZnO NPs. ZnO NPs showed higher cytotoxicity against U87MG (the human glioblastoma cell line) and anti-inflammatory activity against RAW 264.7 (the mouse macrophage cell line) cell lines.