Tea tree oil, a vibrant source of neuroprotection via neuroinflammation inhibition: a critical insight into repurposing Melaleuca alternifolia by unfolding its characteristics / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Over the past few decades, complementary and alternative treatments have become increasingly popular worldwide. The purported therapeutic characteristics of natural products have come under increased scrutiny both in vitro and in vivo as part of efforts to legitimize their usage. One such product is tea tree oil (TTO), a volatile essential oil primarily obtained from the native Australian plant, Melaleuca alternifolia, which has diverse traditional and industrial applications such as topical preparations for the treatment of skin infections. Its anti-inflammatory-linked immunomodulatory actions have also been reported. This systematic review focuses on the anti-inflammatory effects of TTO and its main components that have shown strong immunomodulatory potential. An extensive literature search was performed electronically for data curation on worldwide accepted scientific databases, such as Web of Science, Google Scholar, PubMed, ScienceDirect, Scopus, and esteemed publishers such as Elsevier, Springer, Frontiers, and Taylor & Francis. Considering that the majority of pharmacological studies were conducted on crude oils only, the extracted data were critically analyzed to gain further insight into the prospects of TTO being used as a neuroprotective agent by drug formulation or dietary supplement. In addition, the active constituents contributing to the activity of TTO have not been well justified, and the core mechanisms need to be unveiled especially for anti-inflammatory and immunomodulatory effects leading to neuroprotection. Therefore, this review attempts to correlate the anti-inflammatory and immunomodulatory activity of TTO with its neuroprotective mechanisms.

Avaliação comparativa ?in vivo? da eficácia do óleo de melaleuca, clorexidina e listerine sobre streptococcus mutans e microrganismos totais na saliva / ?In Vivo? Comparative Evaluation of the Efficacy of Melaleuca Oil, Chlorhexidine and Listerine against Streptococcus mutans and Total Microorganisms in Saliva

Objetivo: Comparar a eficácia dos enxaguatórios bucais: clorexidina 0,12%, Listerine e óleo de Melaleuca Alternifolia 0,5% e 2% sobre os níveis salivares de Streptococcus mutans e microrganismos totais. Métodos: O estudo foi um ensaio clínico, controlado, duplo cego e emparelhado. Para tanto foram selecionados 26 voluntários com idade entre 21 - 35 anos. Foi coletada de cada participante, no baseline, a quantidade de 1 mL de saliva não estimulada, 1 e 15 min após os bochechos com as seguintes soluções: água destilada estéril, digluconato de clorexidina 0,12%, Listerine (©Johnson & Johnson do Brasil), Melaleuca Alternifolia (Sigma-Aldrich St Louis, MO, USA) nas concentrações de 0,5% e 2%. Os participantes fizeram uso de todos os enxaguatórios bucais pesquisados, com intervalo de 15 dias entre cada solução. Imediatamente após o bochecho, foi coletada a saliva e realizadas as diluições seriadas, seguidas de plaqueamento em meio de cultura Agar sangue para o crescimento de microrganismos totais e SB-20 (Agar Sacarose Bacitracina) para S. mutans, mantidos por 48h a 37°C em microaerofilia. Após o período de incubação, as colônias foram contadas e transformadas em unidades formadoras de colônias (UFC/mL). Resultados: A clorexidina mostrou ação antimicrobiana na redução dos microrganismos totais e S. mutans, enquanto a ação do óleo Melaleuca Alternifolia 0.5% foi semelhante à água destilada. O listerine e o óleoMelaleuca Alternifolia 2% apresentaram redução microbiana, respectivamente, de 11% e 9% para microrganismos totais, entretanto para S. mutans o listerine reduziu os níveis em 20% e o óleo Melaleuca Alternifolia 2% em 11%. Conclusão: O bochecho único com clorexidina 0,12% é eficaz na redução de níveis de microrganismos totais e S. mutans presentes na saliva. Ao comparar a clorexidina com o listerine e óleo Melaleuca Alternifolia 0,5% e 2% nas mesmas condições a eficácia da ação destas soluções é diminuída.

Objective: To compare the efficacy of the mouthwashes 0.12% chlorhexidine, Listerine, and 0.5% and 2% Melaleuca Alternifolia oil against the salivary levels of Streptococcus mutans and total microorganisms.Methods: This study was double-blind controlled and paired clinical assay. Twenty-six volunteers aged 21 to 35 years old were enrolled. At baseline, 1 mL of unstimulated saliva was collected from each subject, 1 and 15 min after mouthrinsing with the following solutions: sterile distilled water, 0.12% chlorhexidine digluconate, Listerine (©Johnson & Johnson do Brasil), 0.5% and 2% concentrations of Melaleuca Alternifolia (Sigma-Aldrich). The volunteers used all the evaluated mouthrinses with a 15-day interval between the solutions. Immediately after rinsing, saliva was collected and serial dilutions were performed, followed by plating in blood agar culture medium for growth of total microorganisms and SB-20 (Sucrose-Bacitracin agar) for growth of S. mutans, and incubation at 37 °C for 48 h in microaerophilia. After incubation, the number of colonies was counted and expressed as colony forming units (UFC/mL).Results: Chlorhexidine showed antimicrobial action by reducing total microorganisms and S. mutans, while the action of 0.5% Melaleuca Alternifolia was similar to that of distilled water. Listerine and 2%Melaleuca Alternifolia oil reduced total microbial counts by 11% and 9% respectively, and S. mutans by 20% and 11%.Conclusion: A single rinse with 0.12% chlorhexidine is effective in reducing the levels of total microorganisms and S. mutans present in saliva. Under the same testing conditions, Listerine and 0.5% and 2%Melaleuca Alternifolia oil presented lower efficacy than chlorhexidine.

Clinical and Immunological Responses in Ocular Demodecosis

The purpose of this study was to investigate clinical and immunological responses to Demodex on the ocular surface. Thirteen eyes in 10 patients with Demodex blepharitis and chronic ocular surface disorders were included in this study and treated by lid scrubbing with tea tree oil for the eradication of Demodex. We evaluated ocular surface manifestations and Demodex counts, and analyzed IL-1beta, IL-5, IL-7, IL-12, IL-13, IL-17, granulocyte colony-stimulating factor, and macrophage inflammatory protein-1beta in tear samples before and after the treatment. All patients exhibited ocular surface manifestations including corneal nodular opacity, peripheral corneal vascularization, refractory corneal erosion and infiltration, or chronic conjunctival inflammatory signs before treatment. After treatment, Demodex was nearly eradicated, tear concentrations of IL-1beta and IL-17 were significantly reduced and substantial clinical improvement was observed in all patients. In conclusion, we believe that Demodex plays an aggravating role in inflammatory ocular surface disorders.