Green synthesis of zinc oxide nanoparticles using plant extracts of Fumaria officinalis and Peganum harmala and their antioxidant and antibacterial activities

Abstract

The synthesis of nanoparticles using green approaches is gaining unique importance due to its low cost, biocompatibility, high productivity, purity, and being environmentally friendly. So, the current study focused on the green synthesis of zinc oxide nanoparticles (ZnO-NPs) using plant extracts from Fumaria officinalis and Peganum harmala. The characterization was accomplished using techniques such as UV–vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The UV-absorption peaks were observed at 294 and 303 nm. The resulting FT-IR of ZnO-NPs biosynthesized from F. officinalis shoot extract depicts different bands as 593 cm⁻¹, 991 cm⁻¹, 1030 cm⁻¹, and 1229 cm⁻¹, while ZnO-NPs biosynthesized from P. harmala seeds show bands at 600 cm⁻¹, 642 cm⁻¹, 944 cm⁻¹, and 1038 cm⁻¹. FT-IR analysis depicted different functional groups belonging to halo compounds, alkenes, and sulfur oxides. XRD analysis was performed in order to study the structural parameters of ZnO-NPs. XRD analysis confirmed that the average grain size of ZnO-NPs from F. officinalis was 19.55 nm, and the Bragg angles were recorded as 23.25°, 31.75°, 34.4°, 36.25°, 47.5°, 56.55°, 62.8°, and 67.9°. The average grain size for zinc oxide nanoparticles from P. harmala seeds extract was calculated at 25.10 nm, and the Bragg angles are 32.32°, 34.9°, 36.8°, 48.12°, 57.16°, 63.45°, 68.52°, and 69.65°. Moreover, SEM analysis showed that nanoparticles from both plant extracts have irregular rods and dispersed spherical morphology. The most pronounced increases in antioxidant activity against 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic) acid [ABTS] were detected at the high concentrations of ZnO-NPs (400 µg/mL) biosynthesized from F. officinalis (41.67%) and from P. harmala (39.79%), while the lower activity was recorded at a minimum concentration of 50 µg/mL of ZnO-NPs biosynthesized from F. officinalis (30.34%) and from P. harmala (30.28%). Antibiotics revealed smaller inhibition zones of 16 and 17.5 mm, while the higher concentrations of ZnO-NPs (800 µg/mL) biosynthesized from F. officinalis and P. harmala displayed strong antibacterial activity against Staphylococcus aureus with inhibition zones of about 29 and 23 mm and Clavibacter michiganensis with inhibition zones of about 21 and 19 mm, respectively. Antimicrobial resistance is one of the principal global health problems, and it is imperative to develop new drugs to reduce the spread of antimicrobial-resistant microorganisms. So, our finding concludes that we should use the high concentrations of ZnO-NPs (400 µg/mL) biosynthesized from F. officinalis and P. harmala as antioxidant and antibacterial compounds.