Potential of Bouea macrophylla Kernel Extract Against Multispecies Bacterial-fungal Biofilm

Abstract

Object: To determine the antimicrobial activity of B. macrophylla kernel extract in eradication of the multispecies biofilm of E. faecalis, S. gordonii and C. albicans in in vitro and in ex vivo tooth model. Methods: Firstly, antimicrobial effect of B. macrophylla kernel extract to multispecies biofilm of E. faecalis, S. gordonii and C. albicans was determined by AlamarBlueTM assay and The LIVE/DEAD® BacLightTM viability test. Then, multispecies biofilm of E. faecalis, S. gordonii and C. albicans (1:1:1) were inoculated in tooth model for 21 days and the teeth were randomly divided into 4 medicament groups: (i) normal saline, (ii) calcium hydroxide (Ca(OH)2), (iii) chlorhexidine gel, (iv) B. macrophylla kernel extract. The teeth were medicated for 7 days, then dentin sample were harvested and the efficacy of medicament was determined by qPCR with PMA for quantify composition of E. faecalis, S. gordonii and C. albicans. Scanning electron microscope (SEM) was used to visualize the effect of medicament on biofilm structure. Results: The in vitro assay revealed that the MBIC was 6.25 mg/mL and the MBEC was 50 mg/mL. The integrity of microbial cells was progressively compromised as concentration increased, resulting in greater cell death. Ex vivo tooth model revealed that biofilm treated with 50 mg/mL of the B. macrophylla extract demonstrated a significantly higher proportions of dead cells than in Ca(OH)2 , chlorhexidine and normal saline groups (p<0.01). Further, disruption of biofilm structure and enlargement of dentinal tubules was observed in B. macrophylla group on SEM.