Background: COVID-19 patients are vulnerable to develop secondary microbial infections that are frequently multidrug-resistant (MDR) and increase the severity of the disease and mortality risk, which has created an urgent need for the use of natural products as antimicrobial agents.
Objective: This study aimed to evaluate and compare the polyphenol content of some honeybee products from different origins as well as their antimicrobial activity against some MDR secondary microbial infections in COVID-19 patients.
Methods: During the winter of 2021, sixteen clinical microbial isolates were collected from sputum and chest swabs of COVID-19 patients from some hospitals in Cairo, Egypt, and their antimicrobial susceptibility testing was performed. The total phenolic content (TPC) and total flavonoid content (TFC) of eight honeybee products from different origins were evaluated, and their antimicrobial activity was determined by recording the inhibition zone diameter (IZD) and minimum inhibitory concentration (MIC).
Results: According to results, Turkish propolis, Egyptian royal jelly sample1, and Egyptian honey contained the highest polyphenol content and consequently showed significant antimicrobial activity compared to other bee products under study. Turkish propolis contained elevated polyphenol contents (TPC= 322.33 mg Gallic acid (GAE)/100 g and TFC= 88.974 mg Quercetin (QUE)/100 g) and expressed its antimicrobial activity with IZD ranging 15.33–28.33 mm and MIC value of 0.105–7.5 mg/ml. Also, Egyptian royal jelly1 and Egyptian honey contained high polyphenol contents (TPC= 134.737 mg GAE/100 g and TFC= 78.162 mg QUE/100 g) and (TPC= 98.571 mg GAE/100 g and TFC= 44.487 mg QUE/100 g), respectively, and showed antimicrobial activity with IZD of 0.00–21.66 mm and 0.00–22.00 mm, respectively, as well as MIC values of 1.150–4.69% and 6.25–37.50%, respectively. Indeed, all honey and royal jelly samples showed no activity against Candida spp., while propolis exhibited good action against it.
Conclusion: Honeybee products are promising natural products that possess unique antimicrobial activities that help to fight MDR secondary microbial infections in COVID-19 patients, in which their antimicrobial activity is largely affected by polyphenol contents and geographical origins.