The Impact of Azadirachta Indica Extract on the Expression Profile of Esp Gene in Treated Enterococcus faecalis

Enterococcus faecalis is a bacterium often associated with persistent endodontic infections, posing challenges for effective root canal disinfection and treatment outcomes due to its resilience in adverse root canal conditions and resistance to antimicrobial therapies. This study aimed to investigate the effects of Azadirachtaindica's active plant compounds at subinhibitory concentrations on the expression of the virulence gene (esp) in Enterococcus faecalis strains (ATCC 29212).

Azadirachta indica (neem) specimens were obtained in Erbil, Northern Iraq, and the active compounds from the dried plant samples were extracted. Dry extracts were dissolved in Dimethylsulphoxide (DMSO) until reaching 100 mg/ml. Bacterial samples were treated with the extracted plant material and incubated. The assessment of relative esp gene expression in treated Enterococcus faecalis strains (ATCC 29212) began with total RNA extraction using the RNXplus kit, followed by a Quantitative RT-PCR assay.

The minimum concentration of Azadirachta indica's ethyl acetate fraction 3 (30 mg/ml) inhibited the growth of the targeted bacteria. In contrast, the highest concentration inhibiting the target bacteria was 50 mg/ml of fraction 6 (Azadirachta indica-water). All fractions of Azadirachta indica decreased the expression of the target gene, with fraction 5 (ethyl alcohol) showing the highest fold change.

The ethyl alcohol extraction of Azadirachta indica inhibited the expression of the virulence gene (esp) by 2.84-fold, suggesting a potential decrease in (esp) gene expression, which could be considered as an alternative to classical irrigants.