In vitro effects of Melaleuca alternifolia essential oil on growth and production of volatile sulphur compounds by oral bacteria

ABSTRACT Objective Halitosis can be caused by microorganisms that produce volatile sulphur compounds (VSCs), which colonize the surface of the tongue and subgingival sites. Studies have reported that the use of natural products can reduce the bacterial load and, consequently, the development of halitosis. The aim of this study was to evaluate the antimicrobial activity of the essential oil of Melaleuca alternifolia on the growth and volatile sulphur compound (VSC) production of oral bacteria compared with chlorhexidine. Material and Methods The effects of these substances were evaluated by the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) in planktonic cultures of Porphyromonas gingivalis and Porphyromonas endodontalis. In addition, gas chromatography analyses were performed to measure the concentration of VSCs from bacterial cultures and to characterize M. alternifolia oil components. Results The MIC and MBC values were as follows: M. alternifolia - P. gingivalis (MIC and MBC=0.007%), P. endodontalis (MIC and MBC=0.007%=0.5%); chlorhexidine - P. gingivalis and P. endodontalis (MIC and MBC=1.5 mg/mL). M. alternifolia significantly reduced the growth and production of hydrogen sulfide (H2S) by P. gingivalis (p<0.05, ANOVA-Dunnet) and the H2S and methyl mercaptan (CH3SH) levels of P. endodontalis (p<0.05, ANOVA-Dunnet). Chlorhexidine reduced the growth of both microorganisms without altering the production of VSC in P. endodontalis. For P. gingivalis, the production of H2S and CH3SH decreased (p<0.05, ANOVA-Dunnet). Conclusion M. alternifolia can reduce bacterial growth and VSCs production and could be used as an alternative to chlorhexidine.

In vitro effects of Melaleuca alternifolia essential oil on growth and production of volatile sulphur compounds by oral bacteria.

OBJECTIVE: Halitosis can be caused by microorganisms that produce volatile sulphur compounds (VSCs), which colonize the surface of the tongue and subgingival sites. Studies have reported that the use of natural products can reduce the bacterial load and, consequently, the development of halitosis. The aim of this study was to evaluate the antimicrobial activity of the essential oil of Melaleuca alternifolia on the growth and volatile sulphur compound (VSC) production of oral bacteria compared with chlorhexidine. MATERIAL AND METHODS: The effects of these substances were evaluated by the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) in planktonic cultures of Porphyromonas gingivalis and Porphyromonas endodontalis. In addition, gas chromatography analyses were performed to measure the concentration of VSCs from bacterial cultures and to characterize M. alternifolia oil components. RESULTS: The MIC and MBC values were as follows: M. alternifolia - P. gingivalis (MIC and MBC=0.007%), P. endodontalis (MIC and MBC=0.007%=0.5%); chlorhexidine - P. gingivalis and P. endodontalis (MIC and MBC=1.5 mg/mL). M. alternifolia significantly reduced the growth and production of hydrogen sulfide (H2S) by P. gingivalis (p<0.05, ANOVA-Dunnet) and the H2S and methyl mercaptan (CH3SH) levels of P. endodontalis (p<0.05, ANOVA-Dunnet). Chlorhexidine reduced the growth of both microorganisms without altering the production of VSC in P. endodontalis. For P. gingivalis, the production of H2S and CH3SH decreased (p<0.05, ANOVA-Dunnet). CONCLUSION: M. alternifolia can reduce bacterial growth and VSCs production and could be used as an alternative to chlorhexidine.

Vellozia flavicans Mart. ex Schult. hydroalcoholic extract inhibits the neuromuscular blockade induced by Bothrops jararacussu venom.

BACKGROUND: Snakebite is a significant public health issue in tropical countries. In Brazil, some of the most common snake envenomations are from Bothrops. Bothrops bites trigger local and systemic effects including edema, pain, erythema, cyanosis, infections, and necrosis. Vellozia flavicans is a plant from the Brazilian "cerrado" (savanna) that is popularly used as an anti-inflammatory medicine. Since inflammation develops quickly after Bothrops bites, which can lead to infection, the aim of the present study was to observe possible anti-snake venom and antimicrobial activities of V. flavicans (Vf). METHODS: The chromatographic profile of the main constituents from the Vf leaf hydroalcoholic extract was obtained by thin-layer chromatography (TLC). The anti-snake venom activity was measured by Vf's ability to neutralize the in vitro neuromuscular blockade caused by Bothrops jararacussu venom (Bjssu) in a mouse phrenic nerve-diaphragm model (PND). After a 20 min incubation, preparations of PND were added to Tyrode's solution (control); Vf (0.2, 0.5, 1, and 2 mg/mL); 40 µg/mL Bjssu; pre-incubation for 30 min with Bjssu and 1 mg/mL Vf; and a Bjssu pretreated preparation (for 10 min) followed by 1 mg/mL Vf. Myographic recording was performed, and the contractile responses were recorded. The antimicrobial activity (minimum inhibitory concentration [MIC] and minimum bactericidal concentration [MBC]) was obtained for Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Enterococcus faecalis, using gentamicin and vancomycin as positive controls. RESULTS: TLC analysis yielded several compounds from Vf, such as flavonoids (quercetin) and phenolic acids (chlorogenic acid). Bjssu completely blocked the contractile responses of PND preparations, while Vf preserved 97% (±10%) of the contractile responses when incubated with Bjssu. In the PND pretreated with Bjssu, Vf was able to inhibit the neuromuscular blockade progress. MIC and MBC of Vf ranged from 2.5 to 5.0 mg/mL for P. aeruginosa and S. aureus strains, while no antimicrobial activity was observed for E. coli and E. faecalis. CONCLUSIONS: The hydroalcoholic extract from Vf leaves was able to neutralize and decrease the in vitro neuromuscular blockade caused by Bjssu. However, it did not show significant antimicrobial activity against the tested bacteria.

Atividade do óleo de melaleuca alternifólia sobre o crescimento e expressão gênica de Porphyromonas gingivalis / Evaluation of Melaleuca alternifolia activity on growth and gene expression of Porphyromonas gingivalis

As doenças periodontais são infecções causadas por microrganismos que colonizam a superfície dental na margem gengival ou abaixo dela. Entre eles estão os patógenos periodontais, como Porphyromonas gingivalis. Estudos demonstraram que o óleo essencial extraído de Melaleuca alternifolia tem atividade inibitória e bactericida contra microrganismos da cavidade oral. Este estudo teve como objetivo avaliar a interferência do óleo de Melaleuca (MO) sobre o crescimento e virulência de P. gingivalis, comparando com a atividade da clorexidina (CL). Culturas dessa bactéria foram expostas a diferentes concentrações de MO e CL a fim de avaliar a atividade antimicrobiana através dos testes de concentração inibitória mínima (CIM) e concentração bactericida mínima (CBM). Foi realizada uma análise da expressão diferencial de genes relacionados ao estresse oxidativo e à virulência de P. gingivalis através da técnica de RT-PCR, utilizando concentrações sub-CIM de MO e CL. As CIM e CBM encontradas para MO foram de 0,007% e para CL 1,5 μg/mL. O óleo de melaleuca reduziu significativamente a expressão dos genes de virulência kgp e ragA, e do estresse oxidativo dps, oxyR e sodB, enquanto que a CL reduziu a expressão do gene tpx (ANOVA, Bonferroni, p<0,05). O presente estudo concluiu que o óleo de Melaleuca possui ótima atividade inibitória e bactericida contra a bactéria P. gingivalis, além de reduzir de forma significante a expressão dos genes relacionados à virulência e ao estresse oxidativo, podendo ter um valor terapêutico futuro, principalmente no tratamento das periodontites.

Periodontal diseases are infections caused by microorganisms that colonize the tooth surface at the gingival margin or beneath it. Porphyromonas gingivalis is considered an important pathogen for chronic periodontitis. Studies have shown that the essential oil extracted from Melaleuca alternifolia has inhibitory and bactericidal activity against microorganisms from the oral cavity. Therefore, this study aimed to evaluate the effects of Melaleuca essential oil (MO) on growth and virulence of P. gingivalis, comparing to the activity of chlorhexidine (CL). Cultures of P. gingivalis were exposed to different concentrations of CL and MO to evaluate the antimicrobial activity by testing the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). An analysis of differential expression of genes related to oxidative stress and virulence of P. gingivalis was carried out through RT-PCR method, using sub-MIC concentrations of MO and CL. The MIC and MBC were found to be 0.007% for MO and 1.5 μg/mL for CL. MO significantly reduced the expression of virulence genes kgp and ragA, and oxidative stress genes dps, oxyR and sodB, while CL reduced the expression of the tpx gene (ANOVA, Bonferroni, p<0.05). This study concluded that Melaleuca essential oil presents an excellent inhibitory and bactericidal activity against the bacterium P. gingivalis, and significantly reduces the expression of genes related to virulence and oxidative stress, so may have a therapeutic value, particularly for periodontitis.