The Effect of Propolis Extract from Sumatra, Indonesia on Escherichia coli and IL-6 Gene Expression in Male Wistar Rats Fed with a High-Fat Diet

Propolis is a resinous substance produced by honey bees. It was collected from Sumatera, Indonesia, and its antibacterial properties against Escherichia coli and immunomodulatory effect on local intestinal inflammation was evaluated after ingestion of chow and high-fat diets. Male Wistar rats (Rattus norvegicus) were divided into four groups: chow diet (NCD), chow diet with propolis supplementation (NCDP), high-fat diet (HFD), and high-fat diet with propolis supplementation (HFDP) groups. The diets and propolis were administered according to the group assignment for 12 weeks. Faecal samples of the mice were collected at weeks 0, 4, and 12 and subjected to Escherichia coli quantitative real-time polymerase chain reaction (qRT-PCR). Further, reverse transcription-PCR (RT-PCR) analysis was performed using intestinal samples to analyze the interleukin-6 (IL-6) levels. In the NCDP group, E. coli gene expression decreased significantly at week 4 (p < 0.005) and remained low at week 12, whereas in the HFDP group, a significant decrease was observed in week 12. Meanwhile, in obese rats treated with propolis, the expression of the IL-6 gene was found to be high, although not statistically significant (p > 0.005). This study demonstrated the antibacterial effect of propolis against E. coli in normal and obese rats and indicated that propolis supplementation might exert an immunomodulatory effect in obese rats.