Antimicrobial effects of frankincense extracts on oral pathogens
Poster Number
26
Introduction/Abstract
Introduction:
Boswellia trees are the source of frankincense extracts that can be found throughout the Middle East and parts of Africa and Asia. Although frankincense is a precious commodity for trading, it is also used as a traditional medicine for sustainable, cost-effective therapeutic purposes. The bioactive components of the extract have been identified and characterized to have diverse effects on cancer, microbial infections, and inflammation. However, the potential antimicrobial effects of frankincense extracts on oral bacteria are still to be elucidated.
Methods:
In all experiments, two oral bacteria were tested: Porphyromonas gingivalis and Fusobacterium nucleatum. Minimum inhibitory concentration (MIC) was used to determine the minimum concentration of frankincense extracts that inhibit the growth of the two oral pathogens. The effects of different concentrations of frankincense extracts on biofilm formation were determined in vitro using a colorimetric assay to measure biofilm production. Biofilm reduction staining was used to determine the effects of different concentrations of frankincense oil on oral pathogens’ preexisting biofilms. Lactate dehydrogenase (LDH) quantification was used to determine whether frankincense extracts are toxic to human gingival cells.
Result and significance:
The MIC assays show that frankincense extracts inhibited P. gingivalis and F. nucleatum growth in vitro. At different concentrations, frankincense extracts also inhibited biofilm formation and reduced pre-formed biofilms made by both oral bacteria. Finally, low concentrations of frankincense extracts were not toxic to gingival epithelial cells. Our results show the potential antimicrobial activity against oral pathogens of a natural product extracted from Boswellia trees.
Purpose
Frankincense extract contains bioactive components that are suspected to have an antimicrobial effect on pathogens involved in diseases in the mouth. The purpose of this project is to investigate the potential antimicrobial effects of frankincense extracts on two oral microbes involved with gum disease.
Method
In all experiments, two oral bacteria were tested: Porphyromonas gingivalis and Fusobacterium nucleatum. Minimum inhibitory concentration (MIC) was used to determine the minimum concentration of frankincense extracts that inhibit the growth of the two oral pathogens. The minimum inhibitory concentration values of the frankincense extract were determined using a broth microdilution assay. A 24hr culture of P. gingivalis or F. nucleatum were diluted in freshly prepared medium with a concentration of 1 x 10^7 CFU/mL. Equal volumes (100μL) of bacteria culture and frankincense extracts (two-fold dilutions from 512μg/mL to 0.5μg/mL) in fresh medium were mixed in the wells of 96-well plates. 100μL of the suspension was added onto a blood agar plate. Suspensions of only bacteria, only medium, bacteria treated with 1μL of penicillin/streptomycin were used as controls. The plates were incubated for 7 days under anaerobic conditions.
The effects of different concentrations of frankincense extracts on biofilm formation were determined in vitro using a colorimetric assay to measure biofilm production. A 24hr culture of P. gingivalis or F. nucleatum were diluted in freshly prepared medium with a concentration of 2 x 10^7 CFU/mL. Equal volume (500μL) of bacteria and frankincense extracts (two-fold dilutions from 256μg/mL to 0.5μg/mL) in fresh medium were mixed in the wells of a 24-well tissue culture plate. Wells with only bacteria, only medium, and bacteria treated with 10μL of penicillin/streptomycin were used as controls. The 24-well plate was incubated for 48hrs under anaerobic conditions to assess biofilm growth. Poorly attached bacterial cells were washed off with PBS. The biofilms were fixed with methanol and stained with 0.1% (w/v) crystal violet for 15mins. The excess crystal violet was washed off with distilled water and 300μL of methanol was added to dissolve the crystal violet on the biofilms. The methanol was transferred to a 96-well microplate and the optical density was recorded at 560nm.
Biofilm reduction staining was used to determine the effects of different concentrations of frankincense oil on oral pathogens’ pre-fomed biofilms. Briefly, a 24hr culture of P. gingivalis or F. nucleatum were diluted in freshly prepared medium with a concentration of 2 x 10^7 CFU/mL and added on 24-well plates to be incubated under anaerobic conditions. After 48hrs, different concentrations of frankincense extracts were added on top of the bacterial biofilms, and incubated for an additional 24hrs under anaerobic conditions. Wells with only bacteria and only medium were used as controls. The biofilm staining and quantification on a 96-well plate was performed as previously described above.
Lactate dehydrogenase (LDH) quantification was used to determine whether frankincense extracts were toxic to human gingival cells. The cytotoxic effects of frankincense extracts on human gingival cells were assessed using a 24-well microplate via lactate dehydrogenase (LDH) quantification. Human gingival cells (1 x 10^5 cells/mL) were incubated overnight at 37C with 5% CO2. Wells with only human gingival cells were used as control. Then, the cells were treated with frankincense extracts (two-fold dilutions from 128μg/mL to 0.5μg/mL). The plate was then incubated for 24hrs at 37C with 5% CO2. The supernatant was then collected for LDH quantification following the manufacturer’s instruction.
All experiments were performed 3-4 times. All data were plotted and statistical analyses were performed using GraphPrism. T-test was used to compare two groups and two-way ANOVA was used to compare multiple groups. Statistical significance were considered when p<0.05.
Results
The minimum inhibition concentration for P. gingivalis was 32 μg/mL. The minimum inhibition concentration for F. nucleatum was > 512 μg/mL. At different concentrations, frankincense extracts also inhibited biofilm formation and reduced pre-formed biofilms made by both oral bacteria. Finally, low concentrations of frankincense extracts (16 to 0.5 μg/mL) were not toxic to gingival epithelial cells.
Significance
The increase rate of antibiotics drug resistance, the cost of drugs, and the lack of access to healthcare systems for many people, especially in less developed countries, support the need for studying traditional medicines for sustainable, safe, and cost-effective therapeutic purposes. In this project, we show the potential antimicrobial activity of a natural product extracted from Boswellia trees against oral pathogens.
Location
Library and Learning Center, 3601 Pacific Ave., Stockton, CA 95211
Format
Poster Presentation
Antimicrobial effects of frankincense extracts on oral pathogens
Library and Learning Center, 3601 Pacific Ave., Stockton, CA 95211
Introduction:
Boswellia trees are the source of frankincense extracts that can be found throughout the Middle East and parts of Africa and Asia. Although frankincense is a precious commodity for trading, it is also used as a traditional medicine for sustainable, cost-effective therapeutic purposes. The bioactive components of the extract have been identified and characterized to have diverse effects on cancer, microbial infections, and inflammation. However, the potential antimicrobial effects of frankincense extracts on oral bacteria are still to be elucidated.
Methods:
In all experiments, two oral bacteria were tested: Porphyromonas gingivalis and Fusobacterium nucleatum. Minimum inhibitory concentration (MIC) was used to determine the minimum concentration of frankincense extracts that inhibit the growth of the two oral pathogens. The effects of different concentrations of frankincense extracts on biofilm formation were determined in vitro using a colorimetric assay to measure biofilm production. Biofilm reduction staining was used to determine the effects of different concentrations of frankincense oil on oral pathogens’ preexisting biofilms. Lactate dehydrogenase (LDH) quantification was used to determine whether frankincense extracts are toxic to human gingival cells.
Result and significance:
The MIC assays show that frankincense extracts inhibited P. gingivalis and F. nucleatum growth in vitro. At different concentrations, frankincense extracts also inhibited biofilm formation and reduced pre-formed biofilms made by both oral bacteria. Finally, low concentrations of frankincense extracts were not toxic to gingival epithelial cells. Our results show the potential antimicrobial activity against oral pathogens of a natural product extracted from Boswellia trees.
