The comparative effect of propolis and chlorhexidine mouthwash on oral nitrite-producing bacteria and blood pressure regulation.

Background: Propolis mouthwash (PROP-M) has demonstrated antibacterial properties like those of chlorhexidine mouthwash (CHX-M). However, its impact on the abundance of oral nitrite-producing species (NPS) and nitrite-producing activity (NPA) remains unexplored.

Methods: Forty-five healthy individuals were randomised into 2 groups to rinse their mouth twice a day for seven days with either CHX-M (n = 21) or PROP-M (n = 24). Metagenomic sequencing (16S rRNA) was performed on saliva samples collected before and after each treatment. Additionally, salivary biomarkers and blood pressure were measured.

Results: CHX-M increased the relative abundance of NPS (p < 0.001) but significantly impaired the NPA (p < 0.001) compared to baseline and PROP-M. No significant differences in the relative abundance of NPS and NPA were observed in the PROP-M group. However, a significant increase of plasma nitrate (+7 µmol/L, p = 0.047) and a decrease in systolic BP (-2 mmHg, p = 0.022) was observed in this group compared to the baseline.

Conclusion: The results indicate that PROP-M had a smaller effect on the abundance of NPS and NPA compared to CHX-M. Additionally, PROP-M reduced blood pressure in healthy individuals, but this effect was not associated with changes in the oral microbiome.