Efficacy of avocado seed extract in preventing, inhibiting, and eliminating Prevotella intermedia biofilms: An in vitro study

Background and Aim: Prevotella intermedia is a significant contributor to periodontitis, capable of forming biofilms that resist antibiotics and complicate treatment. Avocado seeds (Persea americana Mill.) are rich in bioactive compounds, including flavonoids, tannins, saponins, and alkaloids, which exhibit potential antibiofilm activity. This study aims to evaluate the efficacy of avocado seed ethanol extract in preventing biofilm attachment, inhibiting biofilm formation, and eradicating established biofilms of P. intermedia in vitro. Materials and Methods: A post-test-only control group design was employed using P. intermedia (ATCC 25611). Ten groups were included: Bacterial and negative controls, a positive control (chlorhexidine), and experimental groups with ethanol extract concentrations (3.25%-9.25%). Biofilm activity was assessed using 96-well microtiter plates, crystal violet staining, and optical density measurements at 595 nm to determine the minimum biofilm prevention (MBPC), inhibition (MBIC), and eradication concentrations (MBEC). Statistical analysis was conducted using one-way ANOVA and Bonferroni post hoc tests. Results: Biofilm assays showed a dose-dependent increase in antibiofilm efficacy. The highest attachment prevention (82.67%), biofilm formation inhibition (84.26%), and biofilm eradication (86.04%) were observed at 9.25%. Significant differences (p < 0.05) were found between the extract and negative control groups, with no significant differences (p > 0.05) between the 8.25%-9.25% extracts and chlorhexidine. The MBPC50, MBIC50, and MBEC50 were identified at a concentration of 6.25%, achieving >50% efficacy in biofilm prevention, inhibition, and eradication. Conclusion: Avocado seed ethanol extract demonstrated significant antibiofilm properties against P. intermedia, comparable to chlorhexidine at higher concentrations. The bioactive compounds - flavonoids, tannins, saponins, and alkaloids - likely contributed to these effects through mechanisms such as quorum sensing inhibition, disruption of bacterial adhesion, and destabilization of biofilm structures. These findings highlight avocado seed extract as a promising natural alternative for managing periodontitis-related biofilm infections.