Chemical Composition, Antimicrobial activity, In Vitro Cytotoxicity and Leukotoxin Neutralization of Essential Oil from Origanum vulgare against Aggregatibacter actinomycetemcomitans

Abstract

In this study, the essential oil of Origanum vulgare was evaluated for putative antibacterial activity against six clinical strains and five reference strains of Aggregatibacter actinomycetemcomitans, in comparison with some antimicrobials. The chemical composition of the essential oil was analyzed, using chromatography (CG) and gas chromatography–mass spectrometry coupled (CG–MS). The major compounds in the oil were Carvacrol (32.36%), α-terpineol (16.70%), p-cymene (16.24%), and Thymol (12.05%). The antimicrobial activity was determined by an agar well diffusion test. A broth microdilution method was used to study the minimal inhibitory concentration (MIC). The minimal bactericidal concentration (MBC) was also determined. The cytotoxicity of the essential oil (IC50) was <125 µg/mL for THP-1 cells, which was high in comparison with different MIC values for the A. actinomycetemcomitans strains. O. vulgare essential oil did not interfere with the neutralizing capacity of Psidium guajava against the A. actinomycetemcomitans leukotoxin. In addition, it was shown that the O. vulgare EO had an antibacterial effect against A. actinomycetemcomitans on a similar level as some tested antimicrobials. In view of these findings, we suggest that O.vulgare EO may be used as an adjuvant for prevention and treatment of periodontal diseases associated to A. actinomycetemcomitans. In addition, it can be used together with the previously tested leukotoxin neutralizing Psidium guajava.

Editorial Comments to the Special Issue: “Aggregatibacter actinomycetemcomitans—Gram-Negative Bacterial Pathogen”

“…In the case of an A. actinomycetemcomitans infection with a highly virulent variant of the bacterium, the treatment strategy often involves antibiotics [ 4 ]. Akkaoui and co-workers [ 14 ] demonstrated the efficiency of an essential oil from the plant Origanum vulgare in preventing A. actinomycetemcomitans growth in vitro. The authors found that this effect of the oil was substantially stronger than that of the tested antibiotics.…”

In vitro antibacterial activity of crude ethanolic extract from the leaves of Origanum vulgare, against Staphylococcus aureus ATCC 29213, Pseudomonas aeruginosa ATCC 27853 and Escherichia coli ATCC 25922

“…Likewise, the presence of mean halos of: 21.64,15.24 and 11.45 mm were observed for S. aureus ATCC 29213, for P. aeruginosa ATCC 27853 of 13.31, 12.27 and 7.35 mm, and for E. coli ATCC 25922 of 12.5, 11.4 and 10.6. In other studies, it has been verified that EE had an antibacterial effect against isolated clinical strains with multiple resistance of S. aureus with inhibition halos of 10.44 mm, followed by E. coli with 9.88 mm and P. aeruginosa with 9.77 mm at a concentration of 400 mg/mL 32 , with our results, compared to the aforementioned findings, larger halos were obtained, which may be due to the standard ATCC strains used in the aforementioned study, since concentrations of 80, 40 and 20 mg/mL were used for S. au-reus, E. coli and P. aeruginosa.…”

Actividad antibacteriana in vitro de extracto etanólico crudo de las hojas de Origanum vulgare, frente Staphylococcus aureus ATCC 29213, Pseudomonas aeruginosa ATCC 27853 y Escherichia coli ATCC 25922

“…The antibacterial and antioxidant properties of oregano have been attributed mainly to carvacrol and thymol, which are the main components of its essential oil that cause structural and functional alterations in the cell membrane [9][10][11] , Also in a study, the extracts of leaves of O. vulgare has also been tested for its bactericidal activity against different important pathogens for fish aquaculture [12][13][14] , with findings of activity against bacteria that cause periodontal diseases 15,16 , it is even used in the storage stability of meat and prevent its decomposition 17,18 .…”