Antimicrobial and Antibiofilm Activity of Cinnamon (Cinnamomum burmanii) Extract on Periodontal Pathogens—An in vitro study

Potential targets of phytochemical immunomodulatory therapy in periodontitis immunopathogenesis: A narrative review

Introduction

Periodontitis is one of the most prevalent diseases occurring worldwide, and is caused by an imbalance of host immunological defenses and microbiome profile which occurs in the oral cavity. This imbalance leads to irregularity and uncontrolled activities of immune cells, resulting in over-reactivity of periodontopathogens and tissue destruction. To alleviate periodontitis, exact targeting of specific events involving particular cells could be a potential application of immunomodulatory agents. Phytochemical drug development targeting specific immunopathogenesis events could be a promising complementary, alternative approach to periodontal therapy.

Objectives

This review aimed to explore various events involving a variety of cells in the immunopathogenesis of periodontitis in order to determine potential specific immunomodulation targets for future development of effective phytochemical drugs.

Results

Immunopathogenesis of periodontitis contributes significantly to the disease onset and resolution. Various events occur during the disease development, which involve a variety of immune cells and mediators. Among these, neutrophils, cytokines and lymphocytes, especially Th17 cells, were reported to be the most relevant components in the disease pathogenesis. These components affect the initial responses to periodontopathogens, inhibit oxidative stress formation, control intercellular communication to enhance inflammation, and promote effector cells' migration to induce alveolar bone resorption. Several phytochemical drugs were developed to cure periodontitis, however, the development of phytochemical immunomodulatory drugs to target specific events has not been realized.

Conclusion

This review concluded that development of phytochemical immunomodulatory drugs to target particular events generated by neutrophils, pro-inflammatory cytokines and lymphocytes has tremendous potential to regulate and modulate the immunopathogenesis of periodontitis.

Evaluation of the antibacterial activity of cinnamon essential oil and its individual compounds on Aggregatibacter actinomycetemcomitans isolated from black extrinsic tooth stain: an in vitro study

AIM

Black extrinsic tooth stain (BETS) is a health challenge that commonly affects children. Aggregatibacter actinomycetemcomitans (Aa) presents in higher prevalence within the polymicrobial community of BETS. In this study, the anti-planktonic and anti-sessile activities of cinnamon essential oil (CEO) and its individual compounds against Aa were evaluated. The preventive effect of CEO and its active substances on BETS formation was also studied in vitro.

METHODS

Aa was isolated from a preschool child with BETS and was identified based on the morphological characteristics, MALDI-TOF mass spectroscopy and 16S rRNA sequencing. The effect of CEO and its individual compounds on the growth kinetics of planktonic and sessile Aa cells as well as their antibacterial efficacy and their rate of bacterial killing were examined. The preventive effect of CEO and its active substances on the formation of BETS was evaluated using an ex vivo model. The data were analysed using one-way analysis of variance (ANOVA) and the significance level was set at p < 0.05.

RESULTS

Out of eight individual compounds of CEO, only eugenol, cinnamaldehyde and α-methyl cinnamaldehyde showed anti-Aa activities. The values of the minimum inhibitory concentrations (MICs) were in the following order: CEO (421.5 mg/ml) > α-methyl cinnamaldehyde (26.37 mg/ml) > cinnamaldehyde (0.209 mg/ml) > eugenol (0.052 mg/ml). CEO, eugenol, cinnamaldehyde and α-methyl cinnamaldehyde, respectively, exhibited two-, four-, four- and eightfold increase of sessile MIC compared to their planktonic MIC. The growth kinetics of both planktonic and sessile Aa in the presence of CEO, eugenol, cinnamaldehyde and α-methyl cinnamaldehyde revealed a complete inhibition at the MICs and 5.3%-37.4% biofilm inhibition at sub-MICs. The time-killing study demonstrated that CEO, eugenol and cinnamaldehyde were capable of reducing the survival rate of both planktonic and sessile Aa cells after 15-20 and 25-30 min, respectively. However, α-methyl cinnamaldehyde showed a superior anti-planktonic to anti-biofilm activity. The daily incorporation of CEO, eugenol and cinnamaldehyde at their MICs for 14 days totally prevented the formation of BETS in the ex vivo model; however, in the case of α-methyl cinnamaldehyde, BETS was visually detectable after 10 days.

CONCLUSION

CEO and its individual compounds have marked antibacterial activity against Aa. The effective results against planktonic and sessile Aa within reasonable time indicate that they can be used to prevent BETS.

Chemical Composition of the Cinnamomum malabatrum Leaf Essential Oil and Analysis of Its Antioxidant, Enzyme Inhibitory and Antibacterial Activities

Cinnamomum species are a group of plants belonging to the Lauraceae family. These plants are predominantly used as spices in various food preparations and other culinary purposes. Furthermore, these plants are attributed to having cosmetic and pharmacological potential. Cinnamomum malabatrum (Burm. f.) J. Presl is an underexplored plant in the Cinnamomum genus. The present study evaluated the chemical composition by a GC-MS analysis and antioxidant properties of the essential oil from C. malabatrum (CMEO). Further, the pharmacological effects were determined as radical quenching, enzyme inhibition and antibacterial activity. The results of the GC-MS analysis indicated the presence of 38.26 % of linalool and 12.43% of caryophyllene in the essential oil. Furthermore, the benzyl benzoate (9.60%), eugenol (8.75%), cinnamaldehyde (7.01%) and humulene (5.32%) were also present in the essential oil. The antioxidant activity was indicated by radical quenching properties, ferric-reducing potential and lipid peroxidation inhibition ex vivo. Further, the enzyme-inhibitory potential was confirmed against the enzymes involved in diabetes and diabetic complications. The results also indicated the antibacterial activity of these essential oils against different Gram-positive and Gram-negative bacteria. The disc diffusion method and minimum inhibitory concentration analysis revealed a higher antibacterial potential for C. malabatrum essential oil. Overall, the results identified the predominant chemical compounds of C. malabatrum essential oil and its biological and pharmacological effects.