ANTIBACTERIAL EFFICACY OF PROPOLIS EXTRACTS AGAINST BACTERIAL PATHOGENS

Ahmed Ali Mustafa*, Doaa R. Zahran, Ahmed Saeed Kabbashi, Bnona Izzalddein Abdelrahman, Deyeen Almahdi Deyeen, Maaza Hussein Almubarak, Rowyda Abdelrahman Hamed

ABSTRACT

Background: The global rise in antimicrobial resistance necessitates the search for novel therapeutic agents. Propolis, a natural resinous mixture produced by bees, has garnered significant interest due to its renowned biological properties, including antibacterial activity. Objective: This study aimed to evaluate the in vitro antibacterial activity of sequentially extracted propolis using solvents of increasing polarity (ethyl acetate, ethanol, and water) against a panel of Gram-positive and Gram-negative bacteria. Methods: The antibacterial activity was assessed against Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Salmonella Typhi (ATCC 26850), and Klebsiella pneumoniae (ATCC 27853) using the disc diffusion method to determine the zone of inhibition and a resazurin-based microtiter assay to determine the Minimum Inhibitory Concentration (MIC). Cefoxime was used as a positive control. Results: The ethanol extract yielded the highest extraction yield (49.33%) and demonstrated the most potent antibacterial activity. It exhibited significant inhibition zones against Ps. aeruginosa (34.0±0.50 mm) and K. pneumoniae (26.0± 0.50 mm). The ethyl acetate extract showed activity against Sal. Typhi (23.0±0.50 mm) and E. coli (18.0±0.50 mm), while the aqueous extract was inactive. The MIC values for the active ethanol extract ranged from 0.39 μg/mL for P. aeruginosa to 12.5 μg/mL for S. aureus and S. Typhi. Conclusion: Propolis, particularly its ethanol extract, possesses significant and potent antibacterial activity against a range of clinically relevant pathogens. These findings scientifically validate its traditional use and highlight its potential as a source of natural antimicrobial compounds for combating bacterial infections.

Keywords: Propolis, Antibacterial activity, Minimum Inhibitory Concentration (MIC), Resazurin assay.