Antioxidant, Antimicrobial, and Molecular Docking Studies of Novel Chalcones and Schiff Bases Bearing 1, 4-naphthoquinone Moiety

Background: The 1,4-naphthoquinone ring has attracted prominent interest in the field of medicinal chemistry due to its potent pharmacological activities such as antioxidant, antibacterial, antifungal, and anticancer. Objective: Herein, a series of new Schiff bases (4-6) and chalcones (8a-c & 9a-d) bearing 1,4- naphthoquinone moiety were synthesized in good yields and were subjected to in-vitro antimicrobial, antioxidant, and molecular docking testing. Methods: A facile protocol has been described in this study for the synthesis of new derivatives (4-7, 8ac, and 9a-d) bearing 1,4-naphthoquinone moiety. The chemical structures of all the synthesized compounds were identified by 1H-NMR, 13C-NMR, MS, and elemental analyses. Moreover, these derivatives were assessed for their in-vitro antimicrobial activity against gram-positive, gram-negative bacteria, and fungal strains. Further studies were conducted to test their antioxidant activity using DPPH (2,2-diphenyl- 1-picrylhydrazyl) scavenging assay. Molecular docking studies were realized to identify the most likely interactions of the novel compounds within the protein receptor. Results: The antimicrobial results showed that most of the compounds displayed good efficacy against both bacterial and fungal strains. The antioxidant study revealed that compounds 9d, 9a, 9b, 8c, and 6 exhibited the highest radical scavenging activity. Docking studies of the most active antimicrobial compounds within GLN- 6-P, recorded good scores with several binding interactions with the active sites. Conclusion: Based on the obtained results, it was found that compounds 8b, 9b, and 9c displayed the highest activity against both bacterial and fungal strains. The obtained findings from the DPPH radical scavenging method revealed that compounds 9d and 9a exhibited the strongest scavenging potential. The molecular docking studies proved that the most active antimicrobial compounds 8b, 9b and 9c displayed the highest energy binding scores within the glucosamine-6-phosphate synthase (GlcN-6-P) active site.