Antibacterial properties of Moringa oleifera, Cynara scolymus and Allium fistulosum leaf extracts: molecular docking insights into quercetin's mechanism of action.

BACKGROUND: This study investigates the antioxidant and antibacterial activities of leaf extracts from Moringa oleifera, Cynara scolymus and Allium fistulosum, and explores the role of quercetin, a bioactive compound found in these plants. Antioxidant efficacy was evaluated through DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) radical scavenging assays and reducing power tests, confirming the potent antioxidant potential of these extracts. RESULTS: Antibacterial activity was assessed against various Gram-positive and Gram-negative bacteria using disc diffusion and broth microdilution methods. M. oleifera extract showed significant inhibition zones against Bacillus cereus and Escherichia coli, while extracts from C. scolymus and A. fistulosum demonstrated moderate antibacterial activity across all strains. To understand the molecular basis of these bioactivities, molecular docking studies were performed to evaluate the interactions of quercetin with bacterial proteins 1JIJ, 2XCT and 5BNR, involved in essential bacterial metabolic pathways, cell wall synthesis and DNA replication. The results revealed that quercetin effectively binds to these target proteins, potentially disrupting their function and contributing to the observed antibacterial effects. The findings suggest that the antibacterial activities of the leaf extracts may be partly due to quercetin and its capacity to interfere with key bacterial processes. CONCLUSION: This study provides a mechanistic understanding of the bioactivities of these leaf extracts, highlighting their potential as natural sources of antioxidant and antibacterial agents. Further research is recommended to isolate and quantify quercetin and other active compounds to fully elucidate their roles in these bioactivities. © 2025 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.