Synergistic interaction and mode of action of Citrus hystrix essential oil against bacteria causing periodontal diseases

Abstract

Context: Citrus hystrix de Candolle (Rutaceae), an edible plant regularly used as a food ingredient, possesses antibacterial activity, but there is no current data on the activity against bacteria causing periodontal diseases. Objective: C. hystrix essential oil from leaves and peel were investigated for antibiofilm formation and mode of action against bacteria causing periodontal diseases. Materials and methods: In vitro antibacterial and antibiofilm formation activities were determined by broth microdilution and time kill assay. Mode of action of essential oil was observed by SEM and the active component was identified by bioautography and GC/MS. Results and discussion: C. hystrix leaves oil exhibited antibacterial activity at the MICs of 1.06mg/mL for P. gingivalis and S. mutans and 2.12mg/mL for S. sanguinis. Leaf oil at 4.25mg/mL showed antibiofilm formation activity with 99% inhibition. The lethal effects on P. gingivalis were observed within 2 and 4h after treated with 4×MIC and 2×MIC, respectively. S. sanguinis and S. mutans were completely killed within 4 and 8h after exposed to 4×MIC and 2×MIC of oil. MICs of tested strains showed 4 times reduction suggesting synergistic interaction of oil and chlorhexidine. Bacterial outer membrane was disrupted after treatment with leaves oil. Additionally, citronellal was identified as the major active compound of C. hystrix oil. Conclusions: C. hystrix leaf oil could be used as a natural active compound or in combination with chlorhexidine in mouthwash preparations to prevent the growth of bacteria associated with periodontal diseases and biofilm formation. © 2014 Informa Healthcare USA, Inc. All rights reserved.