Antimicrobial, anti-inflammatory, and antioxidant effect of onion peel extract (Allium cepa L.) on periodontal pathogen Porphyromonas gingivalis: An in vitro analysis

Periodontitis is an inflammatory condition triggered by a host response to pathogenic dental biofilms, particularly Gram-negative anaerobes such as Porphyromonas gingivalis (P gingivalis). Effective management often involves scaling, root planing, and chemical treatments. Herbal remedies, such as onion extracts, have shown potential in combating periodontal pathogens due to their low toxicity and beneficial properties. This interventional study aims to evaluate the antimicrobial, anti-inflammatory, and antioxidant properties of onion peel extract against P gingivalis in an in vitro setting. Onion peels were cleaned, dried, powdered, and extracted using the Soxhlet method. The minimum inhibitory concentration of the extract against P gingivalis was determined. Antioxidant activity was assessed using the 2,2-diphenyl-picryl-hydrazyl assay, and anti-inflammatory effects were evaluated through matrix metalloproteinase (MMP) inhibition assays. The minimum inhibitory concentration for onion peel extract was 0.2 µL/mL, indicating significant antimicrobial activity. The 2,2-diphenyl-picryl-hydrazyl assay revealed 40% antioxidant activity at concentrations ranging from 25 to 100 µL/mL. The anti-inflammatory assay demonstrated a 65% inhibition of MMP-9 and a 72% inhibition of MMP-2, suggesting robust anti-inflammatory effects. The findings suggest that onion peel extract has antibacterial, antioxidant, and anti-inflammatory qualities, implying it could be used therapeutically to treat periodontal diseases. Its effectiveness in lowering P gingivalis growth and inflammation demonstrates its potential as a natural supplement to conventional treatments.