Comparative antioxidant and antimicrobial activities of Nigella sativa flower, leaf, stem, and seed derived silver nanoparticles

This study was aimed to synthesize biogenic silver nanoparticles (AgNPs) using Nigella sativa (N. sativa) plant extracts as bio-reductant. The fabricated nanoparticles were characterized by UV–visible, FTIR, and XRD. The extracts and AgNPs were then evaluated for their antioxidant and antimicrobial potentials using DPPH (2, 2-diphenyl-1-picrylhydrazyl) assay and agar well diffusion assay correspondingly. The color change from pale yellow to tan brownish confirmed the fabrication of nanoparticles. The broad peak from 420 to 430 in the UV–Visible spectrum also confirmed AgNPs formation. In XRD spectrum the peaks indices (1 1 1), (2 0 0), (2 2 0), and (3 1 1) belonging to 2θ values of 38.101, 44.370, 64.179, and 77.549 indicated the presence of silver crystals (JCPDS file no. 00-001-1167). The presence of organic functional groups in the FTIR spectra confirmed the involvement of plant phytochemicals in fabrication of nanoparticles. Comparatively strong antioxidant potential was recorded for silver nanoparticles in comparison to parental extract. The lowest IC50 recorded was in the case flower based AgNPs was 70 µl where it corresponding crude extract resulted in IC50 of 910 µl. Highest IC50 was recorded for stem extract based NPs (100 µl). The antifungal potential of AgNPs from flower was high (24 mm) and that of the stem extract-based NPs was low (19 mm) whereas the antibacterial potential of the stem and seed extract-based extract was comparable however, the leaf and flower-based extract-based NPs were also, substantial. It was concluded from the results that all the whole Nigella sativa plant contained the reductant phytochemicals which be effectively used to fabricate NPs of the desired sizes. The fabricated NPs also exhibited good antioxidant and antimicrobial properties and can be considered as alternative drugs subjected to further verifications of the results in animal model.