A Study on the Effects of Raspberry Extract on Lactic Acid Bacteria, Yeast, and a Simple Simulated Oral Biofilm Model

Abstract

This study aimed to investigate the effects of raspberry extract on lactic acid bacteria, yeast, and a simplified biofilm model associated with oral dental plaque. Raspberry extract was prepared using 70% ethanol at concentrations of 25%, 50%, 75%, and 100%. A 0.12% Chlorhexidine solution and distilled water were used as the positive and negative controls, respectively. Lactic acid bacteria were obtained from 10% natural yogurt, and their activity was evaluated by measuring pH after 24, 48, and 72 h of incubation. The activity of Saccharomyces cerevisiae was assessed by measuring CO2 production at the same time points. The simplified biofilm model was evaluated by measuring the amount of detached biofilm sediment after exposure to the test solutions for 1, 3, 5, and 10 min. Data were analyzed using two-way analysis of variance (two-way ANOVA) followed by Dunnett's multiple comparison test, with statistical significance set at p < 0.05. The results showed that the 0.12% Chlorhexidine group consistently exhibited the highest pH values throughout the experiment. In contrast, the raspberry extract-treated groups showed pH values that varied according to extract concentration and incubation time. The 100% raspberry extract produced the highest CO2 production at 48 and 72 h. In the simplified biofilm model, the amount of detached biofilm sediment increased with exposure time in all groups, and the 50% raspberry extract showed the most comparable effect to 0.12% Chlorhexidine, whereas the 75% and 100% extracts resulted in lower amounts of detached biofilm sediment. In conclusion, raspberry extract affected the pH of lactic acid bacteria, CO2 production by Saccharomyces cerevisiae, and biofilm detachment in a concentration-dependent manner. However, under the conditions of this study, its efficacy remained inferior to that of 0.12% Chlorhexidine, and higher concentrations of raspberry extract may enhance the fermentative activity of yeast.