The majority of nanomaterials have unique properties that make them helpful in a variety of biotechnology applications. The study assesses the phytochemical, antioxidant (using a DPPH radical scavenging assay) and antimicrobial activities and identifies minimum inhibitor concentrations of Citrus sinensis (orange), Citrus Limonum (lemon), and Citrus reticulata (tangerine) extracts and their silver nanoparticles. Fourier Transform Infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) was used to analyze the produced AgNPs. The synthesized AgNPs have a size of less than 100 nm according to SEM examination. Their DPPH radical scavenging activity and reducing power increased in a dose-dependent way that was more than that of their aqueous and alcoholic extracts. In comparison to Staphylococcus aureus and Candida albicans, silver nanoparticles were found to be more efficient towards Escherichia coli. Their activities were increased with increasing dosage. Whereas, no inhibition zones were conducted with the examined plain citrus peel extracts. This finding revealed that the biomolecules that cover nanoparticles can increase metal nanoparticles' biological activity and the organic AgNPs green alcoholic and aqueous extracts from orange, lemon, and tangerine peels could be used as a potential source of new antioxidant and antimicrobial agents.

The present study has shown the screening test of Hawthorn fruits (Crataegus spp.) using crude hydroalcoholic extract and in vitro antimicrobial activity of extracted flavonoid which has shown more antibacterial activity than crude extract with minimal inhibitory concentration (MIC) values ranged from 5% to 2.5%. The amount of total flavonoid and antioxidant activity of Hawthorn fruits (Crataegus spp) in various concentration extracts and antioxidant activities of different concentration extracts were determined by radical scavenging by 2, 2-diphenyl-1-picrylhydrazyl (DPPH • ). The output showed that the contents of flavonoid were found to be 0.386 mg quercet in equivalents (QUE/g). Dried extract displayed remarkable antioxidant activity according to (DPPH • ) assays.

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