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The leaves of Azadirachta indica L. and Melia azedarach L., belonging to Meliaceae family, have been shown to have medicinal benefits and are extensively employed in traditional folk medicine. Herein, HPLC analysis of the ethyl acetate fraction of the total methanolic extract emphasized the enrichment of both A. indica L., and M. azedarach L. leaves extracts with phenolic and flavonoids composites, respectively. Besides, 4 limonoids and 2 flavonoids were isolated using column chromatography. By assessing the in vitro antiviral activities of both total leaves extracts against Severe Acute Respiratory Syndrome Corona virus 2 (SARS-CoV-2), it was found that A. indica L. and M. azedarach L. have robust anti-SARS-CoV-2 activities at low half-maximal inhibitory concentrations (IC50) of 8.451 and 6.922 μg/mL, respectively. Due to the high safety of A. indica L. and M. azedarach L. extracts with half-maximal cytotoxic concentrations (CC50) of 446.2 and 351.4 μg/ml, respectively, both displayed extraordinary selectivity indices (SI>50). A. indica L. and M. azedarach L. leaves extracts could induce antibacterial activities against both Gram-negative and positive bacterial strains. The minimal inhibitory concentrations of A. indica L. and M. azedarach L. leaves extracts varied from 25 to 100 mg/mL within 30 min contact time towards the tested bacteria. Our findings confirm the broad-spectrum medicinal value of A. indica L. and M. azedarach L. leaves extracts. Finally, additional in vivo investigations are highly recommended to confirm the anti-COVID-19 and antimicrobial activities of both plant extracts. [ABSTRACT FROM AUTHOR]

Nanotechnology recently provided useful insight into using a new antibacterial agent with synergistic effects of the bactericide mechanism toward some pathogenic microorganisms. For example, nanosilver and nano zinc oxide represent a class of essential substances that might be widely used in advanced research and healthrelated activities. In the present work, we prepared silver (AgNPs), zinc oxide (ZnONPs) nanoparticles, characterized their structures with "UV-Vis "Spectroscopy, X-ray diffraction (XRD) and High-Resolution Transmission Electron Microscopy (HR-TEM). We then evaluated their antibacterial activity by using different antibiotic discs against Aeromonas hydrophila and Pseudomonas aeruginosa (Gram-negative bacteria), and Staphylococcus aureus (Gram-positive bacteria) isolated from water and fish of Qarun and Manzala Lakes. Also, the minimal inhibitory concentration (MIC) was calculated by the macro dilution method". The obtained results found that AgNPs inhibited the growth of both Gram-positive and Gram-negative bacterial isolates at a concentration of 170 μg/ml. However, ZnONPs inhibited the growth of at 500 μg/ml. Preliminary growth analysis results suggest that silver and zinc oxide nanoparticles have an inhibitory activity on Gram-positive and Gram-negative bacterial isolates. The present study exhibited synthesized (metal, metal oxide) nanoparticles. For potent antibacterial activity, the nanoparticles concentration was considered as a significant factor. Moreover, in low concentrations, Silver nanoparticles inhibited the growth of bacterial strains than zinc oxide nanoparticles. It can be concluded that the application of silver and zinc oxide nanoparticles as antibacterial agents is a promising tool for disease treatment in the field of fish aquaculture. [ABSTRACT FROM AUTHOR]