Antibacterial activity of Indian propolis and its lead compounds against multi-drug resistant clinical isolates

Introduction: The limited anti-infectious drugs and growing antibiotic resistance among pathogenic bacteria underscore the urgent need to explore novel antimicrobial agents, preferably from a natural source. Propolis is the potent natural antimicrobial agent, which produced by honeybees using various plant exudates. However, it has been minimally studied against multidrug-resistant (MDR) microorganisms. In the present study, the authors have investigated the antibacterial activity of ethanolic extracts of Indian melifera propolis (IMP) samples and combinations of their lead compounds against three human clinical isolates. Methods: Three multidrug-resistant microorganisms (MDRMs) were isolated from a human pus sample, and their molecular identification was carried out by 16S rRNA sequencing. The antibacterial activity of the IMP extracts and different combinations of chrysin, galangin, and phenethyl caffeate was determined by minimum inhibitory concentrations (MIC) using the 96-well plate microdilution method. Results: Amongst, 19 IMP studied samples, IMP-5, IMP-14, and IMP-16 samples had the most potent antimicrobial activity against three MDR isolates. These samples had antimicrobial efficacy in the order of IMP16 > IMP14 > IMP5. The combinations of chrysin, galangin, and phenethyl caffeate had the lowest MIC values than individual components and above potent IMP extracts. Conclusions: Certain IMP samples and combinations of chrysin, galangin, and phenethyl caffeate could be the best natural therapeutic agents to control the pathogenicity of MDRMs.

Automated summary

This study investigated the antibacterial activity of ethanolic extracts of Indian melifera propolis (IMP) samples and combinations of their lead compounds against three multidrug-resistant microorganisms (MDRMs). Among 19 IMP samples, IMP-5, IMP-14, and IMP-16 showed the most potent antimicrobial activity against the MDR isolates, with the combinations of chrysin, galangin, and phenethyl caffeate having lower MIC values than individual components and above potent IMP extracts.