No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Activity of Melaleuca alternifolia (tea tree) oil on Influenza virus A/PR/8: Study on the mechanism of action
Abstract
Our previous study demonstrated that Melaleuca alternifolia (tea tree) oil (TTO) had an interesting antiviral activity against Influenza A in MDCK cells. In fact, when we tested TTO and some of its components, we found that TTO had an inhibitory effect on influenza virus replication at doses below the cytotoxic dose; terpinen-4-ol, terpinolene, and alfa-terpineol were the main active components. The aim of this study was to investigate the mechanism of action of TTO and its active components against Influenza A/PR/8 virus subtype H1N1 in MDCK cells. None of the test compounds showed virucidal activity nor any protective action for the MDCK cells. Thus, the effect of TTO and its active components on different steps of the replicative cycle of influenza virus was studied by adding the test compounds at various times after infection. These experiments revealed that viral replication was significantly inhibited if TTO was added within 2h of infection, indicating an interference with an early step of the viral replicative cycle of influenza virus. The influence of the compound on the virus adsorption step, studied by the infective center assay, indicated that TTO did not interfere with cellular attachment of the virus. TTO did not inhibit influenza virus neuraminidase activity, as shown by the experiment measuring the amount of 4-methylumbelliferone, cleaved by the influenza virus neuraminidase from the fluorogenic substrate 2'-O-(4-methylumbelliferyl)-N-acetylneuraminic acid. The effect of TTO on acidification of cellular lysosomes was studied by vital staining with acridine orange using bafilomycin A1 as positive control. The treatment of cells with 0.01% (v/v) of TTO at 37°C for 4h before staining inhibited the acridine orange accumulation in acid cytoplasmic vesicles, indicating that TTO could inhibit viral uncoating by an interference with acidification of intralysosomal compartment.
... Germacrone is derived from Curcumae rhizoma and is reported to be a broad-spectrum antiviral compound due to its ability to act at multiple stages of viral replication process (Wu et al., 2016). Other components such as β-santalol and terpinen-4-ol are also reported to be efficient anti-influenza agents (Garozzo et al., 2011;Paulpandi et al., 2012). ...
... In some cases, applying essential oils changes the endosomal or lysosomal pH, which is crucial during the viral infection. For instance, tea tree essential oil has been reported to interrupt the acidification of the intralysosomal compartment, which is essential for uncoating the influenza virus during the replication process (Garozzo et al., 2011). ...
The SARS-CoV-2 virus, which caused the recent COVID-19 pandemic, is highly contagious due to its exponential transmission rate, unlike other viruses in the coronavirus family. In addition to the usual transmission mode via respiratory droplets, fomite-mediated transmission has been another major cause of its high spreadability. Evidence shows that COVID-19 is transmitted through food packaging, which is believed to act as a fomite for the virus. Various reports also state that SARS-CoV-2 persists for at least three days on the plastic surfaces that form the basis of food packaging. This review highlights the importance of antiviral materials in food packaging to inhibit the fomite-based transmission of viruses. Much research has already been conducted on active antibac-terial/antifungal packaging materials. Most constituent materials of antibacterial packaging, such as polymers, fillers, and active agents, possess antiviral properties and can be used to manufacture antiviral packaging materials. This review discusses these antiviral materials and focuses on their mechanism of action, current use, and recent developments in antiviral food packaging during the COVID-19 pandemic. Also, the research prospects of these materials in the post-pandemic period have been discussed.
... Moreover, treatment with 0.5% carvacrol resulted in the expansion of murine norovirus viral particles, capsid disintegration, and loss of viral infectivity [73]. Garozzo et al. showed that tea tree EO and its major constituent terpinen-4-ol impaired endolysosomal compartment acidification, which inhibited influenza viral uncoating and entry into target cells [74]. Marjoram, clary sage, Thymus vulgaris L., Cinnamomum zeylanicum Blume., Citrus bergamia Risso & Poit., and anise EOs have also been shown to inhibit influenza virus with a half maximal inhibitory concentration (IC50) < 100 µg/mL [75,76]. ...
... Germacrone was also shown to inhibit not only the influenza virus but also feline caliciviruses [78]. Moreover, carvacrol, eugenol, and β-santalol have demonstrated potent anti-influenza virus activities [74,79], including Cinnamomum zeylanicum Blume. essential oil [80]. ...
In this review, we provide an overview of the current understanding of the main mechanisms of pharmacological action of essential oils and their components in various biological systems. A brief introduction on essential oil chemistry is presented to better understand the relationship of chemical aspects with the bioactivity of these products. Next, the antioxidant, anti-inflammatory, antitumor, and antimicrobial activities are discussed. The mechanisms of action against various types of viruses are also addressed. The data show that the multiplicity of pharmacological properties of essential oils occurs due to the chemical diversity in their composition and their ability to interfere with biological processes at cellular and multicellular levels via interaction with various biological targets. Therefore, these natural products can be a promising source for the development of new drugs.
... It is widely used in the fields of biomedicine [1], food preservation [2], and cosmetics [3]. It also has good prospects in resisting germs and tumors [4,5]. In the 1990s, Melaleuca alternifolia was introduced and planted in the red soil region of southern China. ...
... Correlation analysis results show that soil quality index is significantly correlated with biomass, and this correlation can be described by the following linear equation (Equation (4)), and the biomass of Melaleuca alternifolia increases with the increase in soil quality index: Y = 43.254 + 19.896X (n = 15, r = 0.864, p < 0.01) (4) where Y represents biomass of Melaleuca alternifolia (t·ha −1 ) and X represents SQI. ...
Long-term unreasonable management has led to the continuous decline of soil quality in Melaleuca alternifolia planting areas in southern China, and there is no effective way to improve its soil quality at present. In this study, residues of tea tree oil extraction were returned to the forest to explore its influence on soil quality. Therefore, four test groups (RT, residues were tiled; RS, residues were stacked; RDT, residues were decomposed and tiled; RDS, residues were decomposed and stacked) and one control group (CK, nothing was changed) were designed. We used one-way ANOVA and Pearson correlation analysis to detect 22 physical, chemical, and biological indicators of soil, and then used minimum data set (MDS) and principal component analysis (PCA) to evaluate soil quality. The results show that compared with the CK, BD and pH in the test groups decreases, while CP, TTP, SOM, AN, NN, AP, AK, CEC, MBC, MBN, MBP, catalase, urease, sucrase, and ACP increase or strengthen in different degrees, and the biomass increases by 5.3%~12.8%. The soil quality indexes (SQI) are RDT (0.616) > RT (0.546) > RDS (0.525) > RS (0.452) > CK (0.291). Significant correlation between SQI and biomass indicates that the indicators have high biological significance for the planting areas of Melaleuca alternifolia in the red soil region in southern China. These results show that residues could improve soil quality, and that the soil quality is different among different test groups. This study provides a new path for the management of Melaleuca alternifolia plantation.
... The leaf EOs of Melaleuca alternifolia (tea tree oil) contain terpinen-4-ol, terpinolene, and α-terpineol, which showed considerable in vitro activity against the influenza A virus in MDCK cells by interference with acidification of intra-lysosomal compartment [114]. Mosla dianthera is an aromatic herb used in the TCM to treat colds, coughs, nasal congestion, bronchitis, fever, and headache [115]. ...
... The aerial EO of Melaleuca alternifolia, known as tea tree oil (TTO), has been shown in an in silico simulation study to interfere with the entry and fusion activities of the influenza virus [116]. The anti-influenza activity has been attributed to its hydroxylated monoterpenes, terpinen-4-ol, and α-terpineol [114]. Other known groups are hemagglutinin inhibitors [134], M2 ion channel protein inhibitors [135], endosomal and lysosomal inhibitors, also implicated in the TTO [125], protease inhibitors [136], RNA polymerase inhibitors [137], pathway inhibitors [138], neuraminidase inhibitors [139], non-structural protein inhibitors [107], caspase inhibitors [140], glycoprotein/glycosylation inhibitors [141], phospholipase inhibitors [142], release inhibitors [143,144], and autophagy [145]. ...
Essential oils (EOs) are chemical substances, mostly produced by aromatic plants in response to stress, that have a history of medicinal use for many diseases. In the last few decades, EOs have continued to gain more attention because of their proven therapeutic applications against the flu and other infectious diseases. Influenza (flu) is an infectious zoonotic disease that affects the lungs and their associated organs. It is a public health problem with a huge health burden, causing a seasonal outbreak every year. Occasionally, it comes as a disease pandemic with unprecedentedly high hospitalization and mortality. Currently, influenza is managed by vaccination and antiviral drugs such as Amantadine, Rimantadine, Oseltamivir, Peramivir, Zanamivir, and Baloxavir. However, the adverse side effects of these drugs, the rapid and unlimited variabilities of influenza viruses, and the emerging resistance of new virus strains to the currently used vaccines and drugs have necessitated the need to obtain more effective anti-influenza agents. In this review, essential oils are discussed in terms of their chemistry, ethnomedicinal values against flu-related illnesses, biological potential as anti-influenza agents, and mechanisms of action. In addition, the structure-activity relationships of lead anti-influenza EO compounds are also examined. This is all to identify leading agents that can be optimized as drug candidates for the management of influenza. Eucalyptol, germacrone, caryophyllene derivatives, eugenol, terpin-4-ol, bisabolene derivatives, and camphecene are among the promising EO compounds identified, based on their reported anti-influenza activities and plausible molecular actions, while nanotechnology may be a new strategy to achieve the efficient delivery of these therapeutically active EOs to the active virus site.
... The in vitro antifungal activity of Melaleuca alternifolia (tea tree) oil is of great importance. Many of the ingredients found in tea tree oil have been found to have a variety of antifungal effects, particularly against filamentous fungi and dermatophytes (Garozzo et al., 2011). One of the findings showed that the sprouted spores of Aspergillus niger were more susceptible to non-sprouted spores. ...
Currently, the utilization of alternative and complementary therapies in conventional medicine has experienced a surge in popularity. Aromatherapy is a form of complementary therapy that uses essential oils as the primary therapeutic agent for the treatment of various ailments. Various methods are used to extract essential or volatile oils from different sections of the plant, such as flowers, barks, stems, leaves, roots, and fruits. The discovery of the antibacterial and skin permeability qualities of essential oils led to its creation. The primary techniques employed in aromatherapy to allow these oils to permeate the human skin surface and create a noticeable aura are inhalation and local application baths. After entering the body, the oils adjust themselves and perform harmoniously at the location of dysfunction or the area that is impacted. This therapy employs many combinations and variations to alleviate a wide range of disorders such as depression, indigestion, headache, sleeplessness, muscular discomfort, respiratory issues, skin conditions, swollen joints, urinary complications, and more. The efficacy of essential oils is enhanced when one takes into account other factors of life and diet. This chapter provides an overview of therapeutic, medicinal, cosmetic, psychological, olfactory, massage aromatherapy, safety, and botanical studies.
... The potential use of TTO as a disinfectant has been clearly shown in the literature for treating bacteria [1][2][3][4], fungi [5][6][7] and viruses [8][9][10]. The antimicrobial activity of TTO is attributed mainly to the components terpinen-4-ol (35-45%) and 1,8-cineole (1-6%); however, other components such as a-terpineol, terpinolene and a-and c-terpinene are also often present and potentially contribute to microbial disinfection [11][12][13]. ...
In recent years, the need for effective indoor air disinfection procedures and devices has become increasingly important. Numerous studies have highlighted the varying degrees of efficiency with which essential oils control biological aerosols. This project focuses on the antimicrobial activity of tea tree oil, a natural product from Australia, delivered using the “Unitor™ Duct Air Treatment” and “Unitor™ A/C Unit Air Treatment” solutions from Wilhelmsen Ships Service. The study explored multiple scenarios, focusing on the inactivation of bacterial and fungal aerosols in various indoor environments. The findings demonstrated that all tested products efficiently eliminated bacterial and fungal strains, with significant reductions observed even within the first 24 h of treatment. Continued operation over the subsequent six days brought airborne microbial concentrations down to just a few strains per cubic metre. These promising results highlight the potential for the further development of bioaerosol inactivation technologies that employ essential oil vapour discharge over extended periods. The tested products, leveraging the antimicrobial properties of essential oils, present a strong solution for air quality control, particularly in environments prone to high bioaerosol concentrations.
... TTO has been verified to have a number of curing effects while acting as an inflammation reducer [10], and there is ongoing research on its attainable anti-tumor properties [11]. Nevertheless, it is distinguished for its biocidal effects that are antagonistic to an extended range of pathogens, for instance, Staphylococcus aureus (including methicillin-resistant Staphylococcus aureus), [12], a variety of oral bacteria [13], and specific types of viruses, i.e., herpes simplex and influenza viruses [14]. Moreover, TTO has powerful action as opposed to numerous mycelium [15], and there isand there is confirmation of its benefit in managing fluconazole refractory oral candidiasis in HIV-positive patients has been confirmed [16]. ...
Background
Fungal infection is an irritating problem because of the limited number of antifungal drugs and their adverse reactions. Moreover, in the past few years, the resistance of Candida to the existing antifungals has been observed.
Methods
The study sample consisted of 60 male albino rats. Group I received a physiological solution. Group II was subjected to systemic antibiotic treatment 1 week before the application of Candida infused on the tongue dorsum. Group III was subjected to systemic antibiotics, as was group II, for 3 consecutive days, and tea tree oil was applied throughout the experimental period. Ten rats from each group were sacrificed at five and seven weeks and tongue specimens were dissected and prepared for histological and transmission electron microscopic examination.
Results
Histological and TEM results in group II after five and seven weeks revealed marked degenerative changes in the dorsal surface of the rat tongue. Nonetheless, in group III, obvious regeneration of epithelial tongue tissue appeared after seven weeks of treatment with oil.
Conclusion
Tree oil showed antifungal properties against Candida infection, which was confirmed by ultrastructural examination.
... The impact on cellular endosomal and lysosomal acidification was examined through biological staining with acridine orange (AO) (Garozzo et al., 2011). MDCK cells were cultured as monolayers in 24-well flat-bottom plates (Thermo Fisher Scientific) and rinsed twice with MEM-medium. ...
Influenza viruses pose significant public health threats because they can cause seasonal outbreaks and global pandemics. Current preventive measures, including vaccines and antiviral drugs, are limited by their low efficacy and the emergence of drug‐resistant viruses. Addressing these issues necessitates the development of novel preventive and treatment methods. Our previous work highlighted the inhibitory effects of soybean hydrothermal extract on influenza virus growth. In this study, we aimed to delve into the mechanism underlying the antiviral activity, specifically the inhibition of viral entry. Our findings reveal that soybean extract significantly inhibited the stages of viral entry during a viral infection and hindered virus uptake by cells. Fluorescence microscopy of stained viral nucleoproteins demonstrated viral localization on the cell membrane in soybean‐treated cells, highlighting a distinctive pattern compared to the control cells where the virus was internalized. Soybean extract targeted the clathrin‐dependent endocytosis pathway, as evidenced by 76% inhibition using a clathrin‐dependent marker (transferrin). The identification of soybean inhibitors underscores the need for further investigation and offers potential for innovative antiviral interventions.
... The effect of Melaleuca alternifolia oil and its principal components on acidification of cellular lysosomes was studied by vital staining with acridine orange. The findings indicated that Melaleuca alternifolia oil and its primary constituent, terpinen-4-ol, exert a suppressive effect on influenza virus A/PR/8 replication by impeding the lysosome compartment acidification (Garozzo et al. 2011). prostaglandin-endoperoxide synthase-2, HA the haemagglutinin Immune system ...
The rise in viral infections has presented a multitude of public health concerns on a global scale, including the emergence of influenza and SARS-CoV-2. The emergence of drug-resistant virus strains has underscored the paramount importance of expedited research in the development of novel antiviral therapeutics. It has led to a surge in interest in the potential application of essential oils (EOs) as antiviral agents, owing to their noteworthy antiviral efficacy. A considerable number of EOs and their components have demonstrated promising antiviral activities in vitro and in vivo research. This review provided an overview of the various aspects of EOs inhibiting viruses, including plant sources, the different delivery methods, current challenges and strategies for developing drugs, and in-depth discussions on the relevant mechanisms. It concisely explores the antiviral mechanisms of EOs, ranging from molecular docking simulations to in-depth cellular, animal, and human studies. EOs demonstrate antiviral potential by inhibiting viral proteins, disrupting replication, and modulating host cellular functions, immune responses, and nervous system interactions. This review serves as a valuable resource for researchers and pharmaceutical entities, offering insights and references that advance the antiviral research and innovative drug development utilizing plant-derived essential oils.
Graphical abstract
... EO-based disinfectants have been proposed for replication inhibition or inactivation of the influenza virus and coronavirus in vitro [41][42][43]. The benefits of using EOs as alternative disinfectants comprise the application on porous surfaces that cannot be successfully achieved by conventional chemical disinfectants as well as the potential to integrate EOs in blends able to counteract microbes at different replication stages [44]. ...
The hepatitis C virus (HCV) is a major hepatotropic virus that affects humans with increased risk of developing hepatocellular carcinoma. The bovine viral diarrhea virus (BVDV) causes abortion, calf mortality and poor reproductive performance in cattle. Due the difficulties of in vitro cultivation for HCV, BVDV has been used as surrogate for in vitro assessment of the efficacy of antivirals. Essential oils (EOs) display antiviral and virucidal activity on several viral pathogens. In this study, the virucidal activity of five EOs, Salvia officinalis L. EO (SEO), Melissa officinalis L. EO (MEO), Citrus lemon EO (LEO), Rosmarinus officinalis L. EO (REO) and Thymus vulgaris L. EO (TEO) against BVDV was evaluated in vitro at different concentrations for several time contacts. MEO and LEO were able to considerably inactivate BVDV with a time- and dose-dependent fashion. MEO and LEO at the highest concentrations decreased viral titer by 2.00 and 2.25 log10 TCID50/50 μL at 8 h contact time, respectively. SEO, REO and TEO displayed mild virucidal activity at the highest concentrations for 8 h contact times. In this study, the virucidal efficacies of MEO and LEO against BVDV were observed regardless of compound concentration and contact time. Further studies are needed to confirm the potential use of MEO and LEO as surface disinfectants.
... The major constituents of TTO include terpinen-4-ol, γ-terpinene, α-terpinene, 1,8-cineole, and α-terpineol. In addition to antibacterial [10], antiviral [11], and antifungal properties [12], TTO shows anti-inflammatory [13] and antioxidant activity [14]. On the other hand, phenomena such as irritation, allergic reactions, volatilization, and instability in the presence of light or oxygen can be found, which limits the formulation step and thus a therapeutic action [15,16]. ...
Sepsis represents a complex clinical syndrome that results from a harmful host response to infection. The infections most associated with sepsis are pneumonia, intra-abdominal infection, and urinary tract infection. Tea tree oil (TTO) has shown high antibacterial activity; however, it exhibits low aqueous solubility and high volatility, which have motivated its nanoencapsulation. In this study, the performance of nanoemulsions (NE) and nanocapsules (NC) loaded with TTO was compared. These systems were prepared by spontaneous emulsification and nanoprecipitation methods, respectively. Poly-ε-caprolactone or Eudragit® RS100 were tested as polymers for NCs whereas Tween® 80 or Pluronic® F68 as surfactants in NE preparation. Pluronic® F68 and Eudragit® RS100 resulted in more homogeneous and stable nanoparticles. In accelerated stability studies at 4 and 25 °C, both colloidal suspensions (NC and NE) were kinetically stable. NCs showed to be more stable to photodegradation and less cytotoxic than NEs. After sepsis induction by the cecal ligation and puncture (CLP) model, both NE and NC reduced neutrophil infiltration into peritoneal lavage (PL) and kidneys. Moreover, the systems increased group thiols in the kidney and lung tissue and reduced bacterial growth in PL. Taken together, both systems showed to be effective against injury induced by sepsis; however, NCs should be prioritized due to advantages in terms of cytotoxicity and physicochemical stability.
... tree, thyme, and eucalyptus exhibited significant activity (>80%) against HSV-1. Mundinger and Efferth (2008) found the anti-HSV-1 activity of 1,8-cineole. Orhan et al. (2012) found the anti-HSV-1 activity of citral. (−)-α-Pinene and (−)-β-pinene at a concentration of 1 mM exhibited anti-IBV (infectious bronchitis virus) activity (Yang et al. 2011). Garozzo et al. (2011) and Orhan et al. (2012 found that citral, citronellal, and citronellol showed anti-herpes simplex virus-1 activity. Zamora et al. (2016) found that terpinen-4-ol present in the tea tree oil (Melaleuca alternifolia) showed significant activity against the influenza A H1N1/Puerto Rico/8/34 and West Nile viruses. The structures of the abo ...
Essential oils are complex mixtures of plant secondary metabolites composed mostly of terpenoids, aliphatic and aromatic hydrocarbons, and their derivatives such as aldehydes, ketones, alcohols, and esters. They play important roles as defense compounds against microbes, herbivores, and other ecological stress factors according to their structural designs. Among the secondary metabolites, monoterpenes (C10) form the major group. Several reports have shown that both natural monoterpenes and their synthetic derivatives exhibit a wide range of biological activities. In this chapter, a review of the anti-inflammatory, analgesic, antitumor, anticonvulsant, cardioprotective, gastroprotective, wound-healing, antifungal, antibacterial, and antiviral properties of different classes of monoterpenes is discussed.KeywordsPlant secondary metabolitesEssential oilsMEP pathwayMVA pathwayMonoterpenoidsAcyclic monoterpenes
... Accordingly, TTO is beneficial in treating recurrent herpes labialis [36]. TTO is also active against the influenza virus and different coronaviruses, inhibiting their entry into the host cells probably through the interaction of its components with the viral envelope, interfering with the biological activity of key viral structures involved in the fusion process [6,[37][38][39][40][41][42]. On the other hand, non-enveloped viruses are more resistant than enveloped viruses to antiviral/virucidal treatment with essential oils (EOs), including TTO [40,41,43]. ...
Tea Tree Oil (TTO) is an essential oil obtained from the distillation of Melaleuca alternifolia leaves and branches. Due to its beneficial properties, TTO is widely used as an active ingredient in antimicrobial preparations for topical use or in cosmetic products and contains about 100 different compounds, with terpinen-4-ol, γ-terpinene and 1,8-cineole (or eucalyptol) being the molecules most responsible for its biological activities. In this work, the antimicrobial activity of whole TTO and these three major components was evaluated in vitro against fungi, bacteria and viruses. Molecular dynamics simulations were carried out on a bacterial membrane model and a Coxsackievirus B4 viral capsid, to propose an atomistic explanation of their mechanism of action. The obtained results indicate that the strong antimicrobial activity of TTO is attributable to the induction of an altered membrane functionality, mediated by the incorporation of its components within the lipid bilayer, and to a possible ability of the compounds to bind and alter the structural properties of the viral capsid.
... However, they have promising applications as antiviral agents in recurrent herpes infections [112]. Garozzo et al. investigated the mechanism of action of TTO against influenza A (H1N1) virus subtypes and found that TTO does not inhibit influenza virus neuraminidase activity but rather inhibits viral uncoating by interfering with the acidification of the lysosomal internal compartment [113]. Shao et al. showed that TTO has a blocking effect on vesicular stomatitis virus (VSV) replication at the gene and protein level. ...
Airborne viruses, such as COVID-19, cause pandemics all over the world. Virus-containing particles produced by infected individuals are suspended in the air for extended periods, actually resulting in viral aerosols and the spread of infectious diseases. Aerosol collection and detection devices are essential for limiting the spread of airborne virus diseases. This review provides an overview of the primary mechanisms and enhancement techniques for collecting and detecting airborne viruses. Indoor virus detection strategies for scenarios with varying ventilations are also summarized based on the excellent performance of existing advanced comprehensive devices. This review provides guidance for the development of future aerosol detection devices and aids in the control of airborne transmission diseases, such as COVID-19, influenza and other airborne transmission viruses.
... The potential use of Melaleuca alternifolia (Tea tree) oil as a disinfectant has been clearly shown in the literature for treating bacteria [4][5][6], fungi [7,8] and viruses [9,10]. The antimicrobial activity of Tea Tree Oil (TTO) is attributed mainly to terpinen-4-ol (35-45%) and 1,8-cineole (1-6%); however, other components such as a-terpineol, terpinolene and a-and c-terpinene are also often present and potentially contribute to microbial disinfection [11]. ...
Currently, due to the global pandemic caused by severe acute respiratory syndrome coronavirus SARS-CoV-2, new procedures and devices for effective disinfection of indoor air are of obvious interest. Various studies demonstrated quite broad ranges of the efficiency of essential oils in the control of biological aerosols. This project reports the results of investigation of the antimicrobial activity of essential oils natural for Australia (tea tree oil, eucalyptus oil and lemon myrtle) distributed by newly developed VaxiPod device for various scenarios, including bacterial, viral and fungal inactivation on various surfaces and in aerosol form. It was found that the device was capable of operating continuously over 24-h periods, providing sufficient aerosol concentration to efficiently inactivate microorganisms both on the surface and in airborne form. Twenty-four to forty-eight hours were required to achieve inactivation above 90% of most of the tested microbes on solid surfaces (stainless steel discs and agar plates), whilst similar efficiency of inactivation on fibrous filter surface as well as in aerosol form was achieved over 30–60 min of the process run. The results look very promising for further development of bioaerosol inactivating procedures and technologies for air quality control applications.
... Australian tea tree oil, distilled from the leaves of Melaleuca alternifolia or M. linariifolia [1], is a unique type of essential oil that commands high value on the international market. It shows a multitude of bioactive properties, including antimicrobial activity [2,3], antiviral activity [4,5], analgesic properties [6] and anti-inflammatory power [7,8]. Consequently, it is most commonly used to treat skin conditions such as insect bites, superficial wounds, eczma and acne [1 9,10]. ...
Pure Australian tea tree oil is a high-value commodity; however, cheaper tea tree oils are often adulterated with other substances such as eucalyptus oil. Detection of adulteration typically requires time-consuming analysis with expensive equipment. Consequently, rapid methods of screening for adulteration would be beneficial for the industry. This study examined whether the rapid, non-destructive and low-cost methods of ultraviolet-visible and fluorescence spectroscopy could be used to detect adulteration of tea tree oil with eucalyptus oil. Ultraviolet-visible spectroscopy showed moderate accuracy for predicting adulterant concentration (root mean square error of cross-validation (RMSECV) of 6.8% v/v). Moving window analysis was used to reduce the model wavelength range to just 55 nm, without a loss in predictive accuracy. Fluorescence spectroscopy also performed well, with an RMSECV of 2.9% v/v. Consequently, these techniques may be suitable for rapidly and cheaply screening tea tree oil samples for gross adulteration.
... Tea tree oil displays a broad range of biological activities, including antibacterial [4], antifungal [5], antiviral [6,7], acaricidal [8,9], anticarcinogenic [10,11], analgesic [12], anti-inflammatory [13,14] and insecticidal properties [15,16]. There is a notable synergistic activity between the volatile constituents, with Astani, Reichling and Schnitzler [7] finding that the combination of the monoterpene mixture found in natural tea tree oil were less toxic and showed ten times higher antiviral selectivity compared to that of the isolated pure monoterpenes. ...
Essential oil distilled from Melaleuca alternifolia leaves, commonly known as tea tree oil, is well known for its biological activity, principally its antimicrobial properties. However, many samples are adulterated with other, cheaper essential oils such as eucalyptus oil. Current methods of detecting such adulteration are costly and time-consuming, making them unsuitable for rapid authentication screening. This study investigated the use of mid-infrared (MIR) spectroscopy for detecting and quantifying the level of eucalyptus oil adulteration in spiked samples of pure Australian tea tree oil. To confirm the authenticity of the tea tree oil samples, GC-MS analysis was used to profile 37 of the main volatile constituents present, demonstrating that the samples conformed to ISO specifications. Three chemometric regression techniques (PLSR, PCR and SVR) were trialled on the MIR spectra, along with a variety of pre-processing techniques. The best-performing full-wavelength PLSR model showed excellent prediction of eucalyptus oil content, with an R²CV of 0.999 and RMSECV of 1.08% v/v. The RMSECV could be further improved to 0.82% v/v through a moving window wavenumber optimisation process. The results suggest that MIR spectroscopy combined with PLSR can be used to predict eucalyptus oil adulteration in Australian tea tree oil samples with a high level of accuracy.
... The authors deepened the activity against influenza virus of some EOs such as C. bergamia and E. globulus in their vapor phase without characterizing their chemical compositions. In the light of the above, we aimed at studying the activity of the vapors of EOs previously reported for their anti-influenza properties in their liquid phases [16,32,33]. Therefore, we tested bergamot, Chinese star anise, TTO and eucalyptus vapor essential oils for their anti-influenza activities. ...
Influenza viruses are transmitted from human to human via airborne droplets and can be transferred through contaminated environmental surfaces. Some works have demonstrated the efficacy of essential oils (EOs) as antimicrobial and antiviral agents, but most of them examined the liquid phases, which are generally toxic for oral applications. In our study, we describe the antiviral activity of Citrus bergamia, Melaleuca alternifolia, Illicium verum and Eucalyptus globulus vapor EOs against influenza virus type A. In the vapor phase, C. bergamia and M. alternifolia strongly reduced viral cytopathic effect without exerting any cytotoxicity. The E. globulus vapor EO reduced viral infection by 78% with no cytotoxicity, while I. verum was not effective. Furthermore, we characterized the EOs and their vapor phase by the head-space gas chromatography-mass spectrometry technique, observing that the major component found in each liquid EO is the same one of the corresponding vapor phases, with the exception of M. alternifolia. To deepen the mechanism of action, the morphological integrity of virus particles was checked by negative staining transmission electron microscopy, showing that they interfere with the lipid bilayer of the viral envelope, leading to the decomposition of membranes. We speculated that the most abundant components of the vapor EOs might directly interfere with influenza virus envelope structures or mask viral structures important for early steps of viral infection.
... Several studies have described its efficacy against enveloped viruses. In particular, TTO can reduce herpes simplex virus types 1 and 2 (HSV-1 and HSV-2) plaque formation, particularly when applied to the free virus prior to the infection of the cells [28,38], and it can also inhibit influenza virus replication in vitro [25,27,29,39]. Moreover, TTO was also proven to be highly effective in inactivating the influenza virus in vapor form, as a filter coating material or aerosolized in ambient air, suggesting its possible use as a disinfectant in bioaerosol filtration applications or in indoor air quality improvement [27,29]. ...
The COVID-19 pandemic has highlighted the relevance of proper disinfection procedures and renewed interest in developing novel disinfectant materials as a preventive strategy to limit SARS-CoV-2 contamination. Given its widely known antibacterial, antifungal, and antiviral properties, Melaleuca alternifolia essential oil, also named Tea tree oil (TTO), is recognized as a potential effective and safe natural disinfectant agent. In particular, the proposed antiviral activity of TTO involves the inhibition of viral entry and fusion, interfering with the structural dynamics of the membrane and with the protein envelope components. In this study, for the first time, we demonstrated the virucidal effects of TTO against the feline coronavirus (FCoVII) and the human coronavirus OC43 (HCoV-OC43), both used as surrogate models for SARS-CoV-2. Then, to atomistically uncover the possible effects exerted by TTO compounds on the outer surface of the SARS-CoV-2 virion, we performed Gaussian accelerated Molecular Dynamics simulations of a SARS-CoV-2 envelope portion, including a complete model of the Spike glycoprotein in the absence or presence of the three main TTO compounds (terpinen-4-ol, γ-terpinene, and 1,8-cineole). The obtained results allowed us to hypothesize the mechanism of action of TTO and its possible use as an anti-coronavirus disinfectant agent.
... The authors deepened the activity against influenza virus of some EOs such as C. bergamia and E. globulus in their vapor phase without characterizing their chemical compositions. In the light of the above, we aimed at studying the activity of the vapors of EOs previously reported for their anti-influenza properties in their liquid phases [16,32,33]. Therefore, we tested bergamot, Chinese star anise, TTO and eucalyptus vapor essential oils for their anti-influenza activities. ...
Influenza viruses are transmitted from human to human via airborne droplets and can be transferred through contaminated environmental surfaces. Some works have demonstrated the efficacy of essential oils (EOs) as antimicrobial and antiviral agents, but most of them examined the liquid phases, which are generally toxic for oral applications. In our study, we describe the antiviral activity of Citrus bergamia, Melaleuca alternifolia, Illicium verum and Eucalyptus globulus vapor EOs against influenza virus type A. In the vapor phase, C. bergamia and M. alternifolia strongly reduced viral cytopathic effect without exerting any cytotoxicity. The E. globulus vapor EO reduced viral infection by 78% with no cytotoxicity, while I. verum was not effective. Furthermore, we characterized the EOs and their vapor phase by the head-space gas chromatography–mass spectrometry technique, observing that the major component found in each liquid EO is the same one of the corresponding vapor phases, with the exception of M. alternifolia. To deepen the mechanism of action, the morphological integrity of virus particles was checked by negative staining transmission electron microscopy, showing that they interfere with the lipid bilayer of the viral envelope, leading to the decomposition of membranes. We speculated that the most abundant components of the vapor EOs might directly interfere with influenza virus envelope structures or mask viral structures important for early steps of viral infection.
... Even before the discovery of microorganisms, plants were accepted to be effective against infectious diseases (Ríos and Recio 2005). The EOs usually possess antimicrobial activity against bacteria, fungi, protozoans, and viruses (Monzote et al. 2007;Garozzo et al. 2011) which make them promising agents in the treatment of different infections including P. aeruginosa. The EOs molecules interact strongly with cell surface constituents such as membrane proteins and other molecules essential for microbial growth and survival. ...
Pseudomonas aeruginosa is one of the most common pathogens. The antimicrobial peptides and essential oils display narrow-or broad-spectrum activity against bacteria including this strain. The assembly of such information of these molecules in one central resource such as a database would therefore be of great benefit to the exploitation of these bioactive molecules in the present context of increasing antibiotic resistance and natural bio- preservation needs. The database ANTIPSEUDOBASE is created to facilitate access to important information on antimicrobial peptides and essential oils against Pseudomonas aeruginosa.
Now, the database contains calculated or predicted physicochemical properties of 560 sequences of antimicrobial peptides produced by diverse organisms, and general data of 111 essential oils. It permits a quick and easy search of peptides based on their activity as well as their general, physicochemical properties and literature data. These data are very useful to perform further bioinformatic or chemometric analysis and would certainly be useful for the development of new drugs and medical use. The ANTIPSEUDOBASE database is freely available at: (http://bims.pasteur.tn:3838/APP/).
... At a high concentration, tea tree oil exerts a bactericidal effect and can inhibit tumor necrosis factor [29]; thus, tea tree oil can be used as a natural bactericide. Moreover, tea tree oil exerts antiviral effects and can inhibit mold growth, stimulate leukocyte proliferation, increase immune cell activity, enhance immunity, prevent infection, inhibit infection spread, promote wound healing, relieve pain and discomfort, and reduce inflammation [29][30][31]. Tea tree oil is often used for anti-inflammatory purposes in surgery and dental operations [32,33] and is widely used in aromatherapy [34]. ...
To improve business performance and achieve sustainable development through the concept of hot spring resource reuse, this study investigated the antibacterial effect of alginate-coated tea tree essential oil microcapsules and the effect of alginate microcapsules on the release of tea tree essential oil. The results revealed that 450 μm alginate/tea tree essential oil microcapsules (containing 720 ppm of tea tree essential oil) prepared using microfluidic assemblies effectively inhibited total bacteria, Escherichia coli, and Staphylococcus aureus in hot spring water. For alginate/tea tree essential oil microcapsules prepared under different conditions, at a fixed concentration of cross-linking reagents, the release time increased with the cross-linking time (10 min > 5 min > 1 min). At a fixed cross-linking time, the release time increased with the concentrations of cross-linking reagents (1 M > 0.5 M > 0.1 M). When the concentrations of cross-linking reagents and the cross-linking time were the same, the release time of cross-linking reagents increased with the strength of metal activity (Ca > Zn).
Essential oils (EOs) are complex mixtures of volatile compounds, primarily terpenoids and phenolic constituents, derived from plants. They have been widely studied for their diverse biological activities, including antibacterial, antifungal, antiviral, anticancer, and anti-inflammatory effects, among others. These bioactivities are attributed to the unique chemical composition of EOs, which enables multi-targeted modes of action such as disruption of microbial cell membranes, inhibition of spore germination, and modulation of inflammatory pathways. Their potential as alternatives to conventional antimicrobial therapies has gained attention, particularly in addressing antimicrobial resistance. Additionally, EOs exhibit significant antioxidant and antimicrobial properties, contributing to food preservation by preventing spoilage and extending shelf life. In agriculture, their roles in pest management and plant growth regulation highlight their sustainable applications. In conclusion, EOs present a promising avenue for sustainable applications in healthcare, food preservation, and agriculture, though further research is necessary to overcome challenges related to their variability and clinical validation.
The increasing prevalence of viral infections and the emergence of drug-resistant or mutant strains necessitate the exploration of novel antiviral strategies. Accumulating evidence suggests that natural plant products have significant potential to enhance the human antiviral response. Various plant natural products (PNPs) known for their antiviral properties have been evaluated for their ability to modulate immune responses and inhibit viral infections. Research has focused on understanding the mechanisms by which these PNPs interact with the human immune system and their potential to complement existing antiviral therapies. PNPs control compounds such as alkaloids, flavonoids, terpenoids, and polyphenols to promote antiviral cytokine synthesis, increase T-cell and macrophage activity, and activate antiviral genes. Studies have investigated the molecular interactions between PNPs, viruses, and host cells, exploring the potential of combining PNPs with conventional antiviral drugs to enhance efficacy. However, several challenges remain, including identifying, characterizing, and standardizing PNP extracts, optimizing dosages, improving bioavailability, assessing long-term safety, and navigating regulatory approval. The promising potential of PNPs is being explored to develop new, effective, and natural antiviral therapies. This review outlines a framework for an integrative approach to connect the full potential of PNPs in combating viral infections and improving human health. By combining natural plant products with conventional antiviral treatments, more effective and sustainable management of viral diseases can be achieved.
The history of virology is fascinating and could be divided into different eras. Due to their parasitic behavior, viruses greatly impact the development and history of their hosts. When closely examined, almost all organisms have viral parasites; as such, even the tiniest living entities have a major impact on other life forms. The historical impact of viral diseases on hu- man health has prompted virologists to make remarkable efforts to research, comprehend, and eliminate these pathogens. The virologists have significantly advanced scientific research by illuminating novel principles governing life processes.
Background: The world community continues to tackle the life-threatening Coronavirus infection which has spread across the world. In times of pandemic, it is to be expected that people turn to those medicinal plants (MPs) commonly used to protect themselves against disease. Methods: To meet our objectives, we examined all documented findings about the antiviral activity of MPs as well as some other essential compounds, which may act as future research targets for treating Coronavirus (COVID-19). For this purpose, a range of electronic databases have been reviewed up until 15 November 2021: Medline via PubMed, Google Scholar, ScienceDirect and Scopus. Data on MPs that demonstrated one or more of these three actions were recorded, including the extraction method and plant part used, the chemical compounds present, the mechanism of action and the type of study. The compounds in some of these MPs responsible for these activities have also been discussed in the literature. Results: The following findings were obtained: 41 MPs with antiviral activities and 19 phytocompounds under clinical trials. The secondary metabolites with direct or indirect antiviral activity are mainly flavonoids, tannins, phenols, polysaccharides, terpenes, lectins, alkaloids and steroids. Conclusions: These informative data could constitute a starting point for further studies to validate antiviral activities in vivo, as well as meaningful efficacy in humans, for potential therapeutic agents for COVID-19 Keywords: Medicinal plants; Antiviral activity, Phytocompounds; Secondary metabolites, COVID-19 Therapy
Background
Common warts are a common malady among patients. Not only does it affect the person physically but also mentally and socially. Several treatment modalities are available; however, the major concerns are the treatment cost and adverse effect profile. Salicylic + lactic acid (SLA) solution is one of the standard treatment modalities owing to its strong keratolytic properties; however, its cost and adverse effects limit its use among patients. A cost-effective and safe alternative treatment is ideal to bring about a more favorable clinical outcome and better patient satisfaction. 100% tea tree oil (TTO) solution was used in this study due to its natural antiviral and anti-inflammatory properties.
Objective
The study aimed to compare the safety and effectiveness of 100% TTO versus SLA solution in the treatment of common warts.
Methods
A total of 17 patients with a total of 74 warts were included in the study. Each wart was assigned to either of the two treatment groups. the SLA group and the 100% TTO group. A treatment period of 6 weeks was used to assess the effectiveness of both treatment groups.
Results
The study showed no significant difference between the SLA solution and 100% TTO in the treatment of common warts. The 100% tea tree group reported lesser adverse effects. Both treatment groups reported favorable treatment satisfaction.
Conclusion
100% TTO is a potentially safe and cost-effective alternative in the treatment of common warts.
therische Öle (ÄÖ) als Vielstoffgemische sowie einzelne chemisch charakterisierte Ätherisch-Öl-Verbindungen (ÄÖV) haben zahlreiche pharmakologische Wirkungen, wie antibakterielle, antimykotische, antivirale, entzündungshemmende, immunmodulatorische, antioxidative und wundheilungsfördernde. Auf der Grundlage ausgewählter wissenschaftlicher Arbeiten befasst sich die vorliegende Übersicht mit den potenziellen antiviralen und viruziden Aktivitäten von ÄÖ und ÄÖV gegen behüllte und unbehüllte Viren. Neuere In-vitro- und In-vivo-Studien haben gezeigt, dass verschiedene Arznei- und Aromapflanzen antiviral und viruzid wirkende ÄÖ und ÄÖV enthalten, die in der Lage sind, in verschiedenen Wirtszelllinien die Vermehrung von DNA- und RNA-Viren zu behindern, indem sie wichtige Schritte des viralen Infektions-/Replikationszyklus blockieren. In-vivo-Studien an Mäusen mit Viren als Atemwegserreger haben gezeigt, dass verschiedene ÄÖ und ÄÖV das Leben infizierter Tiere verlängern, Virustiter in Gehirn und Lungengewebe reduzieren und die Biosynthese von proinflammatorischen Zytokinen hemmen können. Neuere Arbeiten auf technologischem Gebiet konnten nachweisen, dass nanoverkapselte ÄÖ/ÄÖV eine vielversprechende Möglichkeit darstellen, um die chemische Stabilität, Wasserlöslichkeit, Bioverfügbarkeit und antivirale Wirkung von ÄÖ und ÄÖV zu verbessern.
COVID-19 has been a major global health concern for the past three years, and currently we are still experiencing coronavirus patients in the following years. The virus, known as SARS-CoV-2, shares a similar genomic identity with previous viruses such as SARS-CoV and MERS-CoV. To combat the pandemic, modern drugs discovery techniques such as in silico experiments for docking and virtual screening have been employed to design new drugs against COVID-19. However, the release of new drugs for human use requires two safety assessment steps consisting of preclinical and clinical trials. To bypass these steps, scientists are exploring the potential of repurposing existing drugs for COVID-19 treatment. This approach involves evaluating antiviral activity of drugs previously used for treating respiratory diseases against other enveloped viruses such as HPV, HSV, and HIV. The aim of this study is to review repurposing of existing drugs, traditional medicines, and active secondary metabolites from plant-based natural products that target specific protein enzymes related to SARS-CoV-2. The review also analyzes the chemical structure and activity relationship between selected active molecules, particularly flavonol groups, as ligands and proteins or active sites of SARS-CoV-2.
Viruses are the cause of many human pathogenesis-related conditions. A serious hazard to public health has been created because of the increase in worldwide travel, fast urbanization, and infectious epidemics. At the same time, no preventative vaccines or antiviral treatments are currently available. Resources for developing new antiviral medications can be found in enhanced natural products and herbal medicines. These natural substances have aided the research on developing preventive vaccines and antiviral treatments. Based primarily on in vitro and in vivo searches, this review aims to explore the antiviral properties of plant extracts and some isolated plant natural products. Only a few antiviral medications have been given clinical approval, while numerous viruses continue to elude adequate immunization. Therefore, developing novel antiviral medicines is crucial, and natural substances make excellent sources for these new drugs. This review highlights various natural herbal drugs possessing antiviral properties.
Although the COVID-19 pandemic appears to be diminishing, the emergence of SARS-CoV-2 variants represents a threat to humans due to their inherent transmissibility, immunological evasion, virulence, and invulnerability to existing therapies. The COVID-19 pandemic affected more than 500 million people and caused over 6 million deaths. Vaccines are essential, but in circumstances
in which vaccination is not accessible or in individuals with compromised immune systems, drugs can provide additional protection. Targeting host signaling pathways is recommended due to their genomic stability and resistance barriers. Moreover, targeting host factors allows us to develop compounds that are effective against different viral variants as well as against newly emerging virus strains. In recent years, the globe has experienced climate change, which may contribute to the
emergence and spread of infectious diseases through a variety of factors. Warmer temperatures and changing precipitation patterns can increase the geographic range of disease-carrying vectors, increasing the risk of diseases spreading to new areas. Climate change may also affect vector behavior, leading to a longer breeding season and more breeding sites for disease vectors. Climate change may also disrupt ecosystems, bringing humans closer to wildlife that transmits zoonotic
diseases. All the above factors may accelerate the emergence of new viral epidemics. Plant-derived products, which have been used in traditional medicine for treating pathological conditions, offer structurally novel therapeutic compounds, including those with anti-viral activity. In addition, plant-derived bioactive substances might serve as the ideal basis for developing sustainable/efficient/cost-effective anti-viral alternatives. Interest in herbal antiviral products has increased. More than 50% of approved drugs originate from herbal sources. Plant-derived compounds offer diverse structures and bioactive molecules that are candidates for new drug development. Combining these therapies with conventional drugs could improve patient outcomes. Epigenetics modifications in the genome can affect gene expression without altering DNA sequences. Host cells can use epigenetic
gene regulation as a mechanism to silence incoming viral DNA molecules, while viruses recruit cellular epitranscriptomic (covalent modifications of RNAs) modifiers to increase the translational efficiency and transcript stability of viral transcripts to enhance viral gene expression and replication. Moreover, viruses manipulate host cells’ epigenetic machinery to ensure productive viral infections.
Environmental factors, such as natural products, may influence epigenetic modifications. In this review, we explore the potential of plant-derived substances as epigenetic modifiers for broad-spectrum anti-viral activity, reviewing their modulation processes and anti-viral effects on DNA and RNA viruses, as well as addressing future research objectives in this rapidly emerging field.
Background:
Given the magnitude of influenza pandemics as a threat to the global population, it is crucial to have as many prevention and treatment options as possible. Piceatannol (PIC) is a tetrahydroxylated stilbenoid (trans-3,4,3',5'-tetrahydroxystilbene), also known as 3'- hydroxy resveratrol, which has demonstrated many different biological activities such as anti-inflammatory and antiviral activities.
Purpose:
In this study, the anti-influenza A virus (IAV) activities and mechanisms of PIC in vitro and in vivo were investigated in order to provide reference for the development of novel plant-derived anti-IAV drugs.
Methods:
The viral plaque assay, RT-PCR and western blot assay were used to evaluate the anti-IAV effects of PIC in vitro. The anti-IAV mechanism of PIC was determined by HA syncytium assay, DARTS assay and Surface Plasmon Resonance assay. The mouse pneumonia model combined with HE staining were used to study the anti-IAV effects of PIC in vivo.
Results:
PIC shows inhibition on the multiplication of both H1N1 and H3N2 viruses, and blocks the infection of H5N1 pseudovirus with low toxicity. PIC may directly act on the envelope of IAV to induce the rupture and inactivation of IAV particles. PIC can also block membrane fusion via binding to HA2 rather than HA1 and cleavage site of HA0. PIC may interact with the two residues (HA2-T68 and HA2-I75) of HA2 to block the conformational change of HA so as to inhibit membrane fusion. Importantly, oral therapy of PIC also markedly improved survival and reduced viral titers in IAV-infected mice.
Conclusion:
PIC possesses significant anti-IAV effects both in vitro and in vivo and may block IAV infection mainly through interaction with HA to block membrane fusion. Thus, PIC has the potential to be developed into a new broad-spectrum anti-influenza drug for the prevention and treatment of influenza.
Essential oils (EOs), which are volatile aromatic substances extracted from plants, exhibit antibacterial, antitumor, antiviral, antioxidant, anti-inflammatory, and other effects. Eos are widely used in different fields because of their various biological activities. EOs are volatile and insoluble in water, so their effective utilization rate is greatly reduced. In this regard, researchers propose to use nanotechnology to construct an EOs nanosystem to solve the application problems and improve the utilization rate of EOs. This review summarizes the latest research progress and application status of EOs nanocapsules, EOs nanoemulsion, EOs nanofiber membrane, EOs nanoparticles and EOs nanoliposome, including the methodologies, characteristics and applications.Analyzes the advantages and disadvantages of existing EOs nanotechnology and provides an outlook for future development.
Melaleuca alternifolia essential oil (MaEO) is a green antimicrobial agent suitable for confection eco-friendly disinfectants to substitute conventional chemical disinfectants commonly formulated with toxic substances that cause dangerous environmental impacts. In this contribution, MaEO-in-water Pickering emulsions were successfully stabilized with cellulose nanofibrils (CNFs) by a simple mixing procedure. MaEO and the emulsions presented antimicrobial activities against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Moreover, MaEO deactivated the SARS-CoV-2 virions immediately. FT-Raman and FTIR spectroscopies indicate that the CNF stabilizes the MaEO droplets in water by the dipole-induced-dipole interactions and hydrogen bonds. The factorial design of experiments (DoE) indicates that CNF content and mixing time have significant effects on preventing the MaEO droplets' coalescence during 30-day shelf life. The bacteria inhibition zone assays show that the most stable emulsions showed antimicrobial activity comparable to commercial disinfectant agents such as hypochlorite. The MaEO/water stabilized-CNF emulsion is a promissory natural disinfectant with antibacterial activity against these bacteria strains, including the capability to damage the spike proteins at the SARS-CoV-2 particle surface after 15 min of direct contact when the MaEO concentration is 30 % v/v.
Pseudomonas aeruginosa (P.aeruginosa) is one of the most common pathogens. The antimicrobial peptides and essential oils display narrow-or broad-spectrum activity against bacteria including this strain. The assembly of such information of these molecules in one central resource such as a database would therefore be of great benefit to the exploitation of these bioactive molecules in the present context of increasing antibiotic resistance and natural bio- preservation needs. The database ANTIPSEUDOBASE is created to facilitate access to important information on antimicrobial peptides and essential oils against P.aeruginosa.
Now, the database contains calculated or predicted physicochemical properties of 560 sequences of antimicrobial peptides produced by diverse organisms, and general data of 111 essential oils. It permits a quick and easy search of peptides based on their activity as well as their general, physicochemical properties and literature data. These data are very useful to perform further bioinformatic or chemometric analysis and would certainly be useful for the development of new drugs and medical use. The ANTIPSEUDOBASE database is freely available at: (http://bims.pasteur.tn:3838/APP/).
In the present investigation, the anti-biofilm potential of two essential oils (EOs), Melaleuca alternifolia Chell (Tea-Tree) (TTO) and Eucalyptus globulus Labill. (EEO) was characterized and tested "in vitro" against both mature biofilms and biofilms in the process of formation, produced by strains belonging to three main categories of antibiotic resistant bacteria (ARB): Vancomycin-resistant enterococci (VRE), methicillin-resistant Staphylococcus aureus (MRSA) and broad-spectrum β-lactamase-producing Escherichia coli (ESBL). The study was carried out in 96-well microtiter-plates using EOs alone, in association with each other and in combination with antibiotics against both single and multi-species biofilm. The study demonstrated the ability of TTO and EEO to counteract the ARB strains in sessile form, with promising results in particular against the biofilm in formation. Mature biofilm by ESBL E. coli was the most sensitive in the results from the quantification study of viable cells performed in multi-species biofilms. Lastly, in all tests, carried out using TTO/EEO associations and EOs/antibiotic combinations, the synergistic effect which emerged from the FIC-index has been confirmed, and both the reduction of biofilm in formation, and the removal of mature structure was obtained at very low concentrations, with values from 4 to >512-fold lower than the minimum inhibitory concentration (MIC) of the single compounds.
The leaves of tea tree (Melaleuca alternifolia) plant are the major source of tea tree essential oil extracted via steam distillation. The use of this oil is quite common in cosmetic, pharmaceutical, agrofood, and nonfood industries. The use of essential oils has upshot due to increased demand of natural alternatives to chemically synthesized pharmaceutical and cosmetic products. The aromatic oil of tea tree contains more than 100 different phytochemicals majorly the monoterpenes, sesquiterpenes, and their related alcohols. Terpinen-4-ol has been recognized as a major compound responsible for broad antimicrobial and antiinflammatory activities. Apart from its beneficial effects and natural origin, tea tree oil is subjected to safety concerns like allergic reactions upon topical applications and toxic effects when ingested. In this context, this chapter discusses various aspects of tea tree oil including its phytochemistry, extraction methods, applications, and safety concerns.
The infectious pneumonia induced by drug-resistant Acinetobacter baumannii (DRAB), a hospital-acquired bacterial infection, has a high morbidity and mortality rate. A natural essential oil, tea tree oil (TTO), has a high bactericidal effect without the potential of drug resistance; however, its volatility, hydrophobicity and poor stability limit its applications. Here, TTO nanoemulsions (nanoTTOs) were prepared with the spontaneous-emulsification method. The size of nanoTTOs was 293.2 nm, and the zeta potential was −15.0 mV. They became nebulizers when they were transformed to fine aerosols with a vibrating screen nebulizer. The aerosols had a mass median aerodynamic diameter size of 2.53 μm and a fine particle fraction (1–5 μm) of 86.65%, suitable for pulmonary delivery. The minimum bactericidal concentration (MBC) of nanoTTOs against DRAB was 10.40 mg/mL; while the alkaline nanoTTOs doped with 1.0% NaHCO3 had the MBC of 6.50 mg/mL. Pulmonary delivery of the alkaline nanoTTOs showed obvious therapeutic effects on the DRAB pneumonic mice by downregulating the pro-inflammatory cytokines (IL-1β and IL-6), preventing the bacterial proliferation, and reducing the lung injury, better than ordinary nanoTTOs. Alkaline nanoTTOs are a promising nebulizer formulation for the treatment of bacterial pneumonia, especially drug-resistant bacterial pneumonia.
This study was conducted to investigate the effects of tea tree essential oil (TTO) supplementation in low fish meal diet on growth, lipid metabolism, anti-oxidant capacity and immunity of largemouth bass (Micropterus salmoides). Five low fish meal (175 g kg⁻¹) diets with grade levels of TTO (0, 0.25, 0.5, 1 and 2 g kg⁻¹) were formulated to feed largemouth bass (initial weight: 15.06 ± 0.05 g) for 56 days. The results indicated that supplementation of dietary 1 g kg⁻¹ TTO could significantly improve the weight gain rate, specific growth rate and protein deposition ratio, and decrease the feed conversion rate. The activities of gastric lipase and intestinal trypsin were enhanced by dietary TTO. The width of the intestinal villus was significantly elevated with dietary TTO level. In lipid metabolism parameters, the whole-body crude lipid content was increased and the liver crude lipid content was decreased in TTO treatment groups. The expression of acetyl-CoA carboxylase beta was downregulated, and the mRNA levels of peroxisome proliferator activated receptor alpha and carnitine palmitoyl-transferase 1 were upregulated in the liver by the addition of TTO. The contents of total cholesterol, triglyceride and low-density lipoprotein cholesterol significantly decreased, and the content of high-density lipoprotein cholesterol significantly increased in serum by dietary TTO. In anti-oxidative parameters, catalase activities in the liver and superoxide dismutase activities in the liver, intestine and serum were elevated with dietary TTO level. Malondialdehyde and protein carbonyl contents in the liver, intestine and serum showed the opposite trend. The nf-e2-related factor 2 (Nrf2) signaling pathways in the liver and intestine were triggered by dietary TTO supplementation. In the immune indices, the contents of total protein and albumin were improved, and the contents of glucose, aspartate aminotransferase and alanine transaminase were declined in TTO treatment groups. However, hepatocyte swelling and nuclear migration were found in the liver sections of all groups. After Aeromonas hydrophila administration, the toll-like receptor 2 (TLR2) signaling pathway was activated in the head-kidney, liver and intestine, and the expression levels of interleukin 10 and transforming growth factor beta 1 were increased in the head-kidney, spleen, liver and intestine by dietary TTO. In conclusion, dietary TTO in low fish meal diet could improve growth, anti-oxidant capacity and immunity, and reduce lipid deposition in the liver and serum of largemouth bass. The optimal level of TTO in low fish meal diet of largemouth bass ranged from 1.33 to 1.34 g kg⁻¹.
Understanding the permeation mechanism of natural active compounds through human skin is crucial for advanced cosmetics and drug delivery. In the study, molecular dynamics simulations were used to investigate the structural and dynamical properties of 1,8-Cineole and Terpinen-4-ol (the two main components of tea tree oil) adsorbed on the skin surface. All simulations were performed using the GROMACS (5.0) molecular dynamics package. The skin layer was modeled as a membrane bilayer consisting of ceramides, cholesterol, and free fatty acid. These systems' structural and dynamical properties were characterized by radial distribution function (RDF), self-diffusion coefficient calculated by mean square displacement (MSD), surface tension, and snapshot inspections. It was found that when a single active compound adsorbed on the skin, the increase in surface coverage led to the increase in peak density in RDF for both 1,8- Cineole and Terpinen-4-ol. The self-diffusion coefficient decreased monotonically for 1,8 – Cineole; however, the corresponding value for Terpinen-4-ol increased as surface coverage increased. When both 1.8-Cineole and Terpinen-4-ol were simultaneously adsorbed on the skin, the lowest self-diffusion coefficient and smallest surface tension reduction can be obtained simultaneously at a certain composition value. This study's results can also contribute to the theoretical basis of the special relationship between the ratio composition of the two main active ingredients in tea tree oil (1.8-Cineole and Terpinen-4-ol) on the ability to diffuse and adsorb on the skin surface.
Purpose: Oral squamous cell carcinoma (OSCC) sum 90 to 95 percent of oral cancers and the incidence described men aged 40 to 60 years old. The greater risk factor is the use of tobacco and alcohol, and they are described in independent or combined action. The gold standard method for OSCC diagnosis remain biopsy and histopathological examination. Vital staining, light-based detection systems, auto fluorescence, cytological techniques, molecular analysis, imaging diagnostic, onco-chips were described to obtain early diagnosis. The aim of this study was verifying the correlation of pool of microorganisms, a pool of bacteria, Streptococcus sp, Enterococcus faecalis, and Candida albicans and the presence of OSCC in 4-NQO cancer-induced rats.
Methods: The rats’ saliva was collected one day before the sacrifice of animals. The tongue was gently scraped with a swab while the mouse was immobilized. An Eppendorf vial containing 1 mL of PBS was vortex for 2 minutes and a decimal serial dilution was realized to be plated in selective culture media for streptococcus sp (agar mitis salivarius, staphylococcus (hypertonic egg yolg agar), and for enterococcus faecalis and Candida albicans (saboroud dextrose). After microorganisms’ growth, the number of colony-forming units (CFU/mL) was identified and a log¹⁰ transformation was realized to perform statistical analysis.
Results: Analysis of the histological findings was performed, and the results were described as induced and healthy. The non-statistical difference was verified in Candida albicans, Staphylococcus sp, and Streptococcus sp in 4-NQO induced animals. Correlation analysis was performed using acanthosis, papillary hyperplasia, dysplasia (mild, moderate, and multiple), papilloma, squamous cell carcinoma (SCC [in situ, microinvasive, invasive, and deep invasive]), inflammatory infiltrate (intensity [low, moderate and intense] and type [acute, mixed and chronic]), SCC inflammatory infiltrate, presence of superficial epithelial microorganism and presence of connective microorganism, the pool of microorganisms, the pool of bacteria, data on Streptococcus sp, Enterococcus faecalis and Candida albicans. A positive correlation between the pool of microorganisms with the pool of bacteria (0.98), Candida albicans (0.81), Enterococcus faecalis (0.69), Staphylococcus sp (0.67), invasive-SCC (0.87), inflammatory intensity (0.82) was identified. The bacterium pool shows positive correlation between invasive-SCC (0.78), inflammatory intensity (0.74), Enterococcus faecalis (0.74), Staphylococcus sp (0.71), Candida albicans (0.69). The Streptococcus sp shows a positive correlation between Staphylococcus sp (0.93).
Conclusion:The Candida albicans show a positive correlation between invasive-SCC (0.78) and, inflammatory intensity (0.69). The Staphylococcus sp shows a positive correlation between invasive-SCC (0.70). The pool of microorganisms was correlated to SCC superficial microorganisms (1.00), an acute type of inflammatory infiltrate(1.00), the pool of bacteria (0.79), Candida albicans (0.72), and Enterococcus faecalis (0.79). In the same way, the pool of bacteria showed a correlation with Enterococcus faecalis (0.78). The dysplasia showed a correlation to moderate dysplasia (0.83). The moderate dysplasia showed a statistical correlation with Staphylococcus sp.
The influenza viral infection is threatening the general public since ages due to its high mortality and morbidity rates. There are only few medications available currently for the management of the infection. Both these classes of drugs provide only symptomatic relief, required in high doses, but it also linked with several harmful effects. To minimize various risks of adverse effects and to provide an alternative cure for influenza infection, plant bioactives have been explored since many decades. There are various Chinese traditional medicines, which provide effective therapeutic treatment against the influenza virus. Most importantly, the roots of the Isatis indigotica (Banlangen) and Lianhuaqingwen have significant action against the virus as compared to synthetic drugs. So, there is much other herbal therapeutics, which showed remarkable activity against the influenza infection. This chapter explained about the several bioactives and their mechanism of actions associated with the management of the infection caused by influenza virus.
Natural products, along with food, clothes, and shelter, serve as the basis of treatment since the dawn of human civilization; while the modern medicine has developed over the years by observational and scientific efforts from ancient traditions. Impressive array of bioactivities with minimum or no toxicity was reported with diverse botanicals against several chronic and difficult-to-treat diseases when most synthetic drugs showed unacceptable side effects. A whole range of viral diseases including Dengue, Ebola, drug-resistant Herpes, HIV/AIDS, Japanese Encephalitis, Rabies, SARS, and recent pandemic of SARS Coronavirus-2 need effective prophylactic or therapeutic agents. Considerable research carried out for last few decades on the Pharmacognosy, chemistry; pharmacology and therapeutics of traditionally used medicines of diverse cultures forced most pharmaceutical companies to renew their strategies of drug discovery, from ‘synthetic to green chemistry’, against different stages of virus infection cycle or host-virus interaction where no effective vaccine or drugs exist. Thus, plants or phytochemicals having potentials of preventing or inhibiting viral infection cycle need to studied in-depth with the purity, safely and potency including their standardization, isolation, efficacy, mechanism of action, along with adverse effect on the host to reduce the time and cost of drug discovery. This updated review will portray the in-depth scientific knowledge and steps for the development of nature-based solutions against genetically and functionally diverse viral diseases from age-old traditional medicines.
Objective and Design: To evaluate potential anti-inflammatory properties of tea tree oil, the essential oil steam distilled from the Australian native plant, Melaleuca alternifolia.¶Material and Methods: The ability of tea tree oil to reduce the production in vitro of tumour necrosis factor-α (TNFα), interleukin (IL)-1β, IL-8, IL-10 and prostaglandin E2 (PGE2) by lipopolysaccharide (LPS)-activated human peripheral blood monocytes was examined.¶Results: Tea tree oil emulsified by sonication in a glass tube into culture medium containing 10% fetal calf serum (FCS) was toxic for monocytes at a concentration of 0.016% v/v. However, the water soluble components of tea tree oil at concentrations equivalent to 0.125% significantly suppressed LPS-induced production of TNFα, IL-1β and IL-10 (by approximately 50%) and PGE2 (by approximately 30%) after 40 h. Gas chromatography/ mass spectrometry identified terpinen-4-ol (42%), α-terpineol (3%) and 1,8-cineole (2%, respectively, of tea tree oil) as the water soluble components of tea tree oil. When these components were examined individually, only terpinen-4-ol suppressed the production after 40 h of TNFα, IL-1β, IL-8, IL-10 and PGE2 by LPS-activated monocytes.
Conclusion: The water-soluble components of tea tree oil can suppress pro-inflammatory mediator production by activated human monocytes.
Ribavirin 5′-triphosphate (RTP), derived from the broad-spectrum antiviral compound ribavirin (Virazole), can selectively
inhibit influenza virus ribonucleic acid polymerase in a cell-free assay. Ribavirin and its 5′-monophosphate have no effect
on the polymerase. The inhibition is competitive with respect to adenosine 5′-triphosphate and guanosine 5′-triphosphate.
RTP also inhibits ApG- and GpC-stimulated influenza virus ribonucleic acid polymerase. Since ribavirin is phosphorylated in
the cell, the inhibition of influenza multiplication in the cell may also be caused by RTP.
Bafilomycin A1 is known as a strong inhibitor of the vacuolar type H(+)-ATPase in vitro, whereas other type ATPases, e.g. F1,F0-ATPase, are not affected by this antibiotic (Bowman, E.M., Siebers, A., and Altendorf, K. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 7972-7976). Effects of this inhibitor on lysosomes of living cultured cells were tested. The acidification of lysosomes revealed by the incubation with acridine orange was completely inhibited when BNL CL.2 and A431 cells were treated with 0.1-1 microM bafilomycin A1. The effect was revealed by washing the cells. Both studies using 3-(2,4-dinitroanilino)-3'-amino-N-methyldipropylamine and fluorescein isothiocyanate-dextran showed that the intralysomal pH of A431 cells increased from about 5.1-5.5 to about 6.3 in the presence of 1 microM bafilomycin A1. The pH increased gradually in about 50 min. In the presence of 1 microM bafilomycin A1, 125I-labeled epidermal growth factor (EGF) bound to the cell surface at 4 degrees C was internalized normally into the cells at 37 degrees C but was not degraded at all, in marked contrast to the rapid degradation of 125I-EGF in the control cells without the drug. Immunogold electron microscopy showed that EGF was transported into lysosomes irrespective of the addition of bafilomycin A1. These results suggest that the vacuolar type H(+)-ATPase plays a pivotal role in acidification and protein degradation in the lysosomes in vivo.
Intravascular pH was measured within the lysosomes and newly formed phagosomes in cultured mouse peritoneal macrophages. The kinetics of pH change in both vacuolar systems was quantitatively determined within a large cell population by fluorescence spectroscopy. Additionally, pH changes within individual phagosomes were followed semiquantitatively using indicator dyes. Two novel findings were made. Firstly, the pH in new phagosomes was transiently driven alkaline (higher than physiological) even when the external medium was buffered at pH 6.5. Secondly, perturbations of phagosome-lysosome fusion had little effect upon phagosomal pH changes, even though the compounds used markedly altered the pH of the lysosomes in resting and phagocytosing cells.
Tea tree oil, or the essential oil of Melaleuca alternifolia, is becoming increasingly popular as a naturally occurring antimicrobial agent. The antimicrobial activity of eight components of tea tree oil was evaluated using disc diffusion and broth microdilution methods. Attempts were also made to overcome methodological problems encountered with testing compounds which have limited solubility in aqueous media. After assessing media with and without solubilizing agents, the disc diffusion method was used to determine the susceptibility of a range of micro-organisms to 1,8-cineole, 1-terpinen-4-ol, rho-cymene, linalool, alpha-terpinene, gamma-terpinene, alpha-terpineol and terpinolene. While the disc diffusion method lacked reproducibility, it was considered useful as a procedure for screening for antimicrobial activity. Terpinen-4-ol was active against all the test organisms while rho-cymene demonstrated no antimicrobial activity. Linalool and alpha-terpineol were active against all organisms with the exception of Pseudomonas aeruginosa. Minimum inhibitory and minimum cidal concentrations of each component against Candida albicans, Escherichia coli and Staphylococcus aureus were determined using a broth microdilution method. Modifications to this method overcame solubility and turbidity problems associated with the oil components and allowed the antimicrobial activity of each of the components to be quantified reproducibly. There was reasonable agreement between minimum inhibitory concentrations and zones of inhibition. These results may have significant implications for the future development of tea tree oil as an antimicrobial agent.
A number of viruses replicate in macrophages, some having an obligate requirement for a macrophage host. This raised the question concerning the role of the macrophage endosomal/lysosomal compartment during such infections. Both lysosomotropic weak bases, amantadine and chloroquine, which interfere with endosomal/lysosomal pH gradients, and the macrolide antibiotic bafilomycin A1, which interferes with vacuolar H+-ATPase, inhibited African swine fever (ASF) virus replication in porcine macrophages. This inhibition was reversible: replenishment of bafilomycin, but not amantadine or chloroquine, maintained the inhibition. The characteristics of the inhibition, and the capacity of virus to escape and re-commence replication, related to the capacity of each drug to interfere with the endosomal/lysosomal proton pump. These results demonstrate that the virus actually requires macrophage endosomal/lysosomal activity for its replication. Therein, vacuolar H+-ATPase activity is particularly critical for successful virus replication, which is interesting considering the importance of this for endosomal/lysosomal activity and macrophage function.
FULL TEXT available free from http://jac.oxfordjournals.org/content/53/6/1081.full.pdf+html?sid=5f5df59a-cbba-49f7-b228-04f90be4f537
The aim of this study was to investigate the mechanism of action of tea tree oil and its components against Candida albicans, Candida glabrata and Saccharomyces cerevisiae.
Yeast cells were treated with tea tree oil or components, at one or more concentrations, for up to 6 h. During this time, alterations in permeability were assessed by measuring the leakage of 260 nm absorbing materials and by the uptake of Methylene Blue dye. Membrane fluidity was measured by 1,6-diphenyl-1,3,5-hexatriene fluorescence. The effects of tea tree oil on glucose-induced medium acidification were quantified by measuring the pH of cell suspensions in the presence of both tea tree oil and glucose.
The treatment of C. albicans with tea tree oil and components at concentrations of between 0.25 and 1.0% (v/v) altered both permeability and membrane fluidity. Membrane fluidity was also increased when C. albicans was cultured for 24 h with 0.016%-0.06% (v/v) tea tree oil, as compared with control cells. For all three organisms, glucose-induced acidification of the external medium was inhibited in a dose-dependent manner in the presence of 0.2%, 0.3% and 0.4% tea tree oil.
Data from this study support the hypothesis that tea tree oil and components exert their antifungal actions by altering membrane properties and compromising membrane-associated functions.
FULL TEXT available free from http://cmr.asm.org/content/19/1/50.full.pdf+html?sid=eccd451a-5b42-44f2-b9cc-fe6223ee045a
Complementary and alternative medicines such as tea tree (melaleuca) oil have become increasingly popular in recent decades. This essential oil has been used for almost 100 years in Australia but is now available worldwide both as neat oil and as an active component in an array of products. The primary uses of tea tree oil have historically capitalized on the antiseptic and anti-inflammatory actions of the oil. This review summarizes recent developments in our understanding of the antimicrobial and anti-inflammatory activities of the oil and its components, as well as clinical efficacy. Specific mechanisms of antimicrobial and anti-inflammatory action are reviewed, and the toxicity of the oil is briefly discussed.
The fungicidal and bactericidal actions of the essential oil (EO) of Melaleuca alternifoli a seem well established, but their anti‐inflammatory and antioxidative effects remain unclear. This study investigated in vitro the possible role of whole Melaleuca alternifolia EO as a modulator of the inflammatory/non‐specific immune response by exploring the chemotaxis and kinetic radical oxygen species (ROS) production of leukocytes and cytokine secretion in peripheral blood mononuclear cells (PBMCs) in humans.
The influence of Melaleuca alternifolia EO on the chemotaxis under agarose of isolated neutrophils (PMNs) was evaluated. The kinetics of ROS production by stimulated total circulating leukocytes was followed over 2 h by recording the fluorescence intensity of oxidized dihydrorhodamine 123. The effects of this EO on pro‐(interleukin IL‐2) and anti‐(IL‐4 and IL10) inflammatory cytokine secretions were determined by ELISA following incubation of PBMCs with the EO for 24 h.
Melaleuca alternifolia EO was inefficient on the chemotaxis of PMNs. It exerted an antioxidant effect, reducing ROS production throughout the kinetic study. Melaleuca alternifolia EO inhibited PBMC proliferation, as revealed by a reduction in IL‐2 secretion by stimulated lymphocytes. This EO at 0.1% directly increased the secretion of the anti‐inflammatory cytokine IL‐4 compared with IL‐4 secretion without EO (18.5 ± 10.0 vs 3.3 ± 1, p < 0.05), and also increased IL‐10 secretion at 0.01% (94.9 ± 38.7 vs 44.1 ± 18, ns). Melaleuca alternifolia EO may not only act as an anti‐inflammatory mediator through its antioxidant activity but may also efficiently protect the organism by reducing the proliferation of inflammatory cells without affecting their capacity to secrete anti‐inflammatory cytokines. Copyright © 2006 John Wiley & Sons, Ltd.
Intravascular pH was measured within the lysosomes and newly formed phagosomes in cultured mouse peritoneal macrophages. The kinetics of pH change in both vacuolar systems was quantitatively determined within a large cell population by fluorescence spectroscopy. Additionally, pH changes within individual phagosomes were followed semiquantitatively using indicator dyes. Two novel findings were made. Firstly, the pH in new phagosomes was transiently driven alkaline (higher than physiological) even when the external medium was buffered at pH 6.5. Secondly, perturbations of phagosome-lysosome fusion had little effect upon phagosomal pH changes, even though the compounds used markedly altered the pH of the lysosomes in resting and phagocytosing cells.
Australian tea tree oil from Melaleuca alternifolia and M. linariifolia is well known for exhibiting antibacterial, antifungal, and general antiseptic properties. Hence characterization of tea tree oil is important, as this leads to a better understanding of the important components contributing to the observed properties of the oil. GC/MS is widely used for this task. However, reliable identification of oil components is not always possible using mass spectral data only. Retention times or retention indices are often used to support the MS data. The present study investigated a number of different tea tree and other Melaleuca sp. oil samples, and reports qualitative and quantitative data for each sample. Characterization of the individual oil components was performed using a private MS library, which incorporates an interactive linear retention index filter. The method described in this report increases the ease of characterization of individual oil components, and allows a greater number to be reliably assigned. More than 80% of the components in the samples studied are now reliably identified.
Volatile constituents of essential oils of eight different clones propagated from the Australian tea tree (Melaleuca alternifolia) were analyzed by gas chromatography and gas chromatography/mass spectrometry. The oils isolated by a simultaneous purging and solvent extraction method (SPE) contained high levels of monoterpenes, including α-thujene, sabinene, α-terpinene, γ-terpinene, 1,8-cineole, terpinolene, and limonene. The volatile composition of oils prepared by a simultaneous steam distillation and solvent extraction method (SDE) varied significantly among different clones. Six oils contained 1,8-cineole as the major constituent, whereas two oils had terpinen-4-ol as the major component of the SDE samples. More compounds were found in SDE samples than in SPE samples. A principal component analysis on volatile compositions of eight oils conducted by computer indicated that sabinene and α-thujene in SPE samples and terpinen-4-ol and α-terpinene in SDE samples are highly correlated with each other.
Melaleuca alternifolia has been used for medical purposes since Australia was colonized in 1788. Melaleuca alternifolia is commonly called tea tree, although this vernacular name is also given to many other species in the Leptospermum and Melaleuca genera. A small tree, it grows up to 5 m in height, has papery bark and narrow, tapered leaves up to 20 mm in length and flowers in summer. Melaleuca alternifolia is unique to Australia and its natural habitat is a relatively small area around the Clarence and Richmond rivers in the north-east coastal area of New South Wales where the terrain is generally low lying and swampy. The essential oil of M. alternifolia, or tea tree oil. has enjoyed increased medicinal use in recent years. It is a pale yellow viscous liquid with a distinctive pungent odour and is composed of a complex mixture of monoterpenes, 1-terpinen-4-ol, cineole and other hydrocarbons (Peña 1962).
Abstract : We introduce the use of the pH-sensitive dye acridine orange (AO) to monitor exo/endocytosis of acidic neurotransmitter-containing vesicles in synaptosomes. AO is accumulated exclusively in acidic v-ATPase-dependent bafilomycin (Baf)-sensitive compartments. A fraction of the accumulated AO is rapidly released (fluorescence increase) upon depolarization with KCl in the presence of Ca2+. The release (completed in 5-6 s) is followed by reuptake to values below the predepolarization baseline. The reuptake, but not the release, is inhibited by Baf added 5 s prior to KCl. In a similar protocol, Baf does not affect the initial fast phase of glutamate release measured enzymatically, but it abolishes the subsequent slow phase. Thus, the fast AO release corresponds to the rapid phase of glutamate release and the slow phase depends on vesicle cycling. AO reuptake depends in part on the progressive accumulation of acid-loaded vesicles during cycling. Stopping exocytosis at selected times after KCl by Ca2+ removal with EGTA evidences endocytosis : Its T1/2 was 12 ± 0.6 s. The KA+, channel inhibitors 4-aminopyridine (100 μM) and α-dendrotoxin (10-100 nM) are known to induce glutamate release by inducing the firing of Na+ channels ; their action is potentiated by the activation of protein kinase C. Also these agents promote a Ca2+-dependent AO release, which is prevented by the Na+ channel inhibitor tetrodotoxin and potentiated by 4β-phorbol 12-myristate 13-acetate (PMA). With α-dendrotoxin, endocytosis was monitored by stopping exocytosis at selected times with EGTA or alternatively with Cd2+ or tetrodotoxin. The T1/2 of endocytosis, which was unaffected by PMA, was 12 ± 0.4 s with EGTA and Cd2+ and 9.5 ± 0.5 s with tetrodotoxin. Protein kinase C activation appeared to facilitate vesicle turnover.
To investigate the in vitro antiviral activity of Melaleuca alternifolia essential oil (TTO) and its main components, terpinen-4-ol, alpha-terpinene, gamma-terpinene, p-cymene, terpinolene and alpha-terpineol.
The antiviral activity of tested compounds was evaluated against polio type 1, ECHO 9, Coxsackie B1, adeno type 2, herpes simplex (HSV) type 1 and 2 viruses by 50% plaque reduction assay. The anti-influenza virus assay was based on the inhibition of the virus-induced cytopathogenicity. Results obtained from our screening demonstrated that the TTO and some of its components (the terpinen-4-ol, the terpinolene, the alpha-terpineol) have an inhibitory effect on influenza A/PR/8 virus subtype H1N1 replication at doses below the cytotoxic dose. The ID(50) value of the TTO was found to be 0.0006% (v/v) and was much lower than its CD(50) (0.025% v/v). All the compounds were ineffective against polio 1, adeno 2, ECHO 9, Coxsackie B1, HSV-1 and HSV-2. None of the tested compounds showed virucidal activity. Only a slight virucidal effect was observed for TTO (0.125% v/v) against HSV-1 and HSV-2.
These data show that TTO has an antiviral activity against influenza A/PR/8 virus subtype H1N1 and that antiviral activity has been principally attributed to terpinen-4-ol, the main active component.
TTO should be a promising drug in the treatment of influenza virus infection.
This report describes the preparation of a sodium (4-methylumbelliferyl-α-d-N-acetylneuraminate) substrate and its use in a sensitive fluorometric assay of neuraminidase (EC 3.2.1.18) from Vibrio cholerae, cultured fibroblasts, and human leucocytes. V. cholerae neuraminidase showed maximum activity at pH 4.6 and an apparent Km of 1.5 mm and was activated by CaCl2 and inhibited by ethylenediaminetetraacetate, NaCl, and N-acetylneuraminic acid. The inhibition by N-acetylneuraminic acid was competitive (Ki = 6.1 mm). Cultured fibroblast and leucocyte neuraminidases showed maximum activity between pH 4.2 and 4.4 and apparent Km values of 0.13 and 0.22 mm, respectively. Neuraminidase activity was considerably reduced in cultured fibroblasts of patients with mucolipidosis types I, II, and III.
Ribavirin, a guanosine analogue, is a broad spectrum antiviral agent which is effective in the treatment of influenza. In this study, the effect of ribavirin on influenza virus ribonucleoprotein (RNP) synthesis and nucleotide pool sizes was simultaneously measured. Ribavirin (100 microM) reduced viral RNP synthesis 94% as measured by UTP incorporation. Intracellular GTP pools, measured by high performance liquid chromatography, were reduced approximately 45% in ribavirin treated cells, while other nucleotides remained near control values. Attempts to reverse ribavirin's inhibitory effects on viral RNP synthesis by addition of exogenous guanosine (50 microM) resulted in only a partial restoration of viral RNP synthesis, despite full restoration of the GTP pool. Dose-response experiments indicated that the GTP pool was significantly reduced (65% of control) at 25 microM ribavirin, and increasing concentrations of the drug caused only a small further reduction in the GTP pool (5-10% at 100 microM). In contrast, RNP synthesis was inhibited by 50% at 25 microM ribavirin and was further decreased to 5% of control at 100 microM ribavirin. Thus, ribavirin's antiviral activity may result from a reduction of the GTP pool size combined with direct effects on viral replicative enzymes.
The role that endosomal acidification plays during influenza virus entry into MDCK cells has been analyzed by using the macrolide antibiotics bafilomycin A1 and concanamycin A as selective inhibitors of vacuolar proton-ATPase (v-[H+]ATPase), the enzyme responsible for the acidification of endosomes. Bafilomycin A1 and concanamycin A, present at the low concentrations of 5 x 10(-7) and 5 x 10(-9) M, respectively, prevented the entry of influenza virus into cells when added during the first minutes of infection. Attachment of virion particles to the cell surface was not the target for the action of bafilomycin A1. N,N'-Dicyclohexylcarbodiimide, a nonspecific inhibitor of proton-ATPases, also blocked virus entry, whereas elaiophylin, an inhibitor of the plasma-proton ATPase, had no effect. The inhibitory actions of bafilomycin A1 and concanamycin A were tested in culture medium at different pHs. Both antibiotics powerfully prevented influenza virus infection when the virus was added under low-pH conditions. This inhibition was reduced if the virus was bound to cells at 4 degrees C prior to the addition of warm low-pH medium. Moreover, incubation of cells at acidic pH potently blocked influenza virus infection, even in the absence of antibiotics. These results indicate that a pH gradient, rather than low pH, is necessary for efficient entry of influenza virus into cells.
The selective inhibitor of the vacuolar proton-ATPase, concanamycin A, powerfully blocks influenza virus entry into cells, if present during the initial times of virus infection. Attachment of virus particles to cells is not prevented by concanamycin A, rather the exit of influenza virus from endosomes is the step blocked by this macrolide antibiotic. Inhibition of influenza virus entry into cells by concanamycin A or by nigericin takes place under acidic conditions. Moreover, if the pH gradient is abolished by pre-incubation of cells in acidic pH, influenza virus entry does not occur even in the absence of any inhibitors. These results indicate that acidic conditions per se are not sufficient to promote virus entry into cells; rather this step of virus infection requires a pH gradient.
We studied the effect of bafilomycin A1 (Baf-A1), a novel and highly specific inhibitor for vacuolar-type proton (V-H+) pump, on the growth of influenza A and B viruses in Madin-Darby canine kidney cells. Vital fluorescence microscopic study showed that Baf-A1 induced the complete disappearance of acidified compartments such as endosomes and lysosomes both in infected and uninfected cells by the treatment with 0.1 microM inhibitor for 1 h at 37 degrees C. In addition, virus growth was inhibited when Baf-A1 was present from 1 h before infection to the end of incubation, or added within as early as 5-10 min after infection. Conversely, the virus growth was recovered in correlation with the reappearance of acidified compartments after removal of Baf-A1. These data suggest that Baf-A1-sensitive V-H+ pumps are solely responsible for the acidification of endosomes and lysosomes, and thus Baf-A1 inhibits the growth of influenza A and B viruses by affecting the acidified compartments in which low pH is essential for the uncoating process of influenza virus growth at an early stage of infection.
Safe and effective antiviral agents are needed to prevent infection with influenza A and B virus. Oseltamivir (GS4104), which can be administered orally, is the prodrug of GS4071, a potent and selective inhibitor of influenzavirus neuraminidases. We studied the use of oseltamivir for long-term prophylaxis against influenza in two placebo-controlled, double-blind trials at different U.S. sites during the winter of 1997-1998.
We randomly assigned 1559 healthy, nonimmunized adults 18 to 65 years old to receive either oral oseltamivir (75 mg given once or twice daily, for a total daily dose of 75 or 150 mg) or placebo for six weeks during a peak period of local influenzavirus activity. The primary end point with respect to efficacy was laboratory-confirmed influenza-like illness (defined as a temperature of at least 37.2 degrees C accompanied by at least one respiratory and at least one systemic symptom).
In the two studies combined, the risk of influenza among subjects assigned to either once-daily or twice-daily oseltamivir (1.2 percent and 1.3 percent, respectively) was lower than that among subjects assigned to placebo (4.8 percent; P<0.001 and P=0.001 for the comparison with once-daily and twice-daily oseltamivir, respectively). The protective efficacy of oseltamivir in the two active-treatment groups combined was 74 percent (95 percent confidence interval, 53 to 88 percent) at all the sites combined and 82 percent (95 percent confidence interval, 60 to 93 percent) at sites in Virginia, where the rate of influenza infection was higher than the overall rate. For culture-proved influenza, the rate of protective efficacy in the two oseltamivir groups combined was 87 percent (95 percent confidence interval, 65 to 96 percent). The rate of laboratory-confirmed influenza infection was lower with oseltamivir than with placebo (5.3 percent vs. 10.6 percent, P<0.001). Oseltamivir was well tolerated but was associated with a greater frequency of nausea (12.1 percent and 14.6 percent in the once-daily and twice-daily groups, respectively) and vomiting (2.5 percent and 2.7 percent, respectively) than was placebo (nausea, 7.1 percent; vomiting, 0.8 percent). However, the frequency of premature discontinuation of drug or placebo was similar among the three groups (3.1 to 4.0 percent).
Oseltamivir administered daily for six weeks by the oral route is safe and effective for the prevention of influenza.
Using several herbal extracts, we investigated whether certain Kampo medicines exert an inhibitory effect on the acidification of intracellular compartments such as endosomes and lysosomes (referred to as ELS), and thereby inhibit the growth of influenza A virus in Madin-Darby canine kidney cells. The vital fluorescence microscopic study showed that the extract of Ephedrae herba (EHext) among five herbal extracts inhibited acidification of endosomes and lysosomes in a concentration-dependent manner (100-400 microg/ml). Moreover the growth of influenza A/PR/8/34 (H1N1) (PR8) virus was inhibited when the cells were treated with EHext for 1 h immediately after infection, or treated as early as 5-10 min after infection. Conversely, virus growth resumed concomitantly with the reappearance of acidified ELS after removal of EHext. The fact that the inhibitory effect of EHext was completely or partially reversed by FeCl3, a tannin-reactive agent, strongly suggests that tannin is one of the active components in the extract.
A series of 3-methylthio-5-aryl-4-isothiazolecarbonitriles has been evaluated as anti rhinovirus agents against a panel of 17 representative human rhinovirus (HRV) serotypes, belonging to both A and B groups. No anti rhinovirus activity was detected for 3-methylthio-5-phenyl-4-isothiazolecarbonitrile (IS-2). Isothiazole derivatives with bulky substituents (O-Bn or O-But groups) on the para position of the phenyl ring were the most effective compounds of this series. In fact, a reduction in virus-induced cytopathogenicity was demonstrated for the O-Bn substituted IS-50 compound against the majority (88%) of the rhinoviruses tested, whereas the compound with an O-Ts group (IS-44) was found to be a specific inhibitor of group B serotypes, exhibiting the lowest IC(50) against HRVs type 2, 85 and 89. Our studies on the mechanism of action of IS-44 demonstrated that it prevents the thermal inactivation of HRV 2 infectivity, probably due to a conformational shift in the viral capsid and a decrease in affinity for the cellular receptor, resulting in an inhibition of attachment of the virions.
Determination of the sensitivity of influenza viruses to neuraminidase (NA) inhibitors is presently based on assays of NA function because, unlike available cell culture methods, the results of such assays are predictive of susceptibility in vivo. At present the most widely used substrate in assays of NA function is the fluorogenic reagent 2'-O-(4-methylumbelliferyl)-N-acetylneuraminic acid (MUN). A rapid assay with improved sensitivity is required because a proportion of clinical isolates has insufficient NA to be detectable in the current fluorogenic assay, and because some mutations associated with resistance to NA inhibitors reduce the activity of the enzyme. A chemiluminescence-based assay of NA activity has been developed that uses a 1,2-dioxetane derivative of sialic acid (NA-STAR) as the substrate. When compared with the fluorogenic assay, use of the NA-STAR substrate results in a 67-fold reduction in the limit of detection of the NA assay, from 200 pM (11 fmol) NA to 3 pM (0.16 fmol) NA. A panel of isolates from phase 2 clinical studies of zanamivir, which were undetectable in the fluorogenic assay, was tested for activity using the NA-STAR substrate. Of these 12 isolates with undetectable NA activity, 10 (83%) were found to have detectable NA activity using the NA-STAR substrate. A comparison of sensitivity to zanamivir of a panel of influenza A and B viruses using the two NA assay methods has been performed. IC(50) values for zanamivir using the NA-STAR were in the range 1.0-7.5 nM and those for the fluorogenic assay in the range 1. 0-5.7 nM (n = 6). The NA-STAR assay is a highly sensitive, rapid assay of influenza virus NA activity that is applicable to monitoring the susceptibility of influenza virus clinical isolates to NA inhibitors.
The antiviral effect of Australian tea tree oil (TTO) and eucalyptus oil (EUO) against herpes simplex virus was examined. Cytotoxicity of TTO and EUO was evaluated in a standard neutral red dye uptake assay. Toxicity of TTO and EUO was moderate for RC-37 cells and approached 50% (TC50) at concentrations of 0.006% and 0.03%, respectively. Antiviral activity of TTO and EUO against herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2) was tested in vitro on RC-37 cells using a plaque reduction assay. The 50% inhibitory concentration (IC50) of TTO for herpes simplex virus plaque formation was 0.0009% and 0.0008% and the IC50 of EUO was determined at 0.009% and 0.008% for HSV-1 and HSV-2, respectively. Australian tea tree oil exhibited high levels of virucidal activity against HSV-1 and HSV-2 in viral suspension tests. At noncytotoxic concentrations of TTO plaque formation was reduced by 98.2% and 93.0% for HSV-1 and HSV-2, respectively. Noncytotoxic concentrations of EUO reduced virus titers by 57.9% for HSV-1 and 75.4% for HSV-2. Virus titers were reduced significantly with TTO, whereas EUO exhibited distinct but less antiviral activity. In order to determine the mode of antiviral action of both essential oils, either cells were pretreated before viral infection or viruses were incubated with TTO or EUO before infection, during adsorption or after penetration into the host cells. Plaque formation was clearly reduced, when herpes simplex virus was pretreated with the essential oils prior to adsorption. These results indicate that TTO and EUO affect the virus before or during adsorption, but not after penetration into the host cell. Thus TTO and EUO are capable to exert a direct antiviral effect on HSV. Although the active antiherpes components of Australian tea tree and eucalyptus oil are not yet known, their possible application as antiviral agents in recurrent herpes infection is promising.
FULL TEXT available free from http://jac.oxfordjournals.org/content/48/3/450.full.pdf+html?sid=6ad2516c-d196-44c5-846d-b894cdc5ac64
We previously characterized influenza viruses whose selection in the presence of neuraminidase (NA) inhibitors resulted in a substituted residue (position 119,152,274, or 292) in the NA active center. To identify the most favorable conditions for detecting NA inhibitor-resistant viruses we compared the results of four modifications of the NA inhibition assay utilizing a fluorogenic substrate. The IC50 values were highly dependent upon assay conditions, and most mutant enzymes were more sensitive to changes in assay conditions (e.g. addition of PO4(3-), Ca2+, DMSO, or EDTA) than wild-type enzymes or a mutant NA with an Arg292-->Lys substitution. Although the levels of resistance to zanamivir, oseltamivir carboxylate, and BCX-1812 (RWJ-270201) for each mutant varied among assays, mutants with substitutions at framework residues 119 or 274 exhibited sensitivity to at least one inhibitor. Viruses with substitutions at catalytic residues 152 or 292 were resistant to each inhibitor in all assays. Monitoring resistance in a clinical setting will require a panel of resistant viruses to ensure that assay conditions are favorable for detecting variants with substituted residues in the NA active center. Because variants selected in the presence of one NA inhibitor could be variably resistant to other inhibitors, all three inhibitors should be used in drug susceptibility testing.
It has been previously reported that green-tea extract (GTE) inhibits the growth of influenza virus by preventing its adsorption. In this study, we further investigated whether GTE exerts an additional inhibitory effect on the acidification of intracellular compartments such as endosomes and lysosomes (referred to as ELS) and thereby inhibits the growth of influenza A and B viruses in Madin-Darby canine kidney cells. The vital fluorescence microscopic study showed that GTE inhibited acidification of ELS in a concentration-dependent manner. Moreover, the growth of influenza A and B viruses was equally inhibited when the cells were treated with GTE within as early as 5 to 15 min after infection, depending on the virus strains. The fact that (-)epigallocatechin (EGC), one of major catechin molecules in GTE, exerts the inhibitory effects on the acidification of ELS and virus growth in a manner similar to that of GTE strongly suggests that EGC is one of the active components in the extract.
To date, of the Australian essential oils, only tea tree (Melaleuca alternifolia) and Eucalyptus spp. have undergone extensive investigation. In this study a range of Australian essential oils, including those from Anethole anisata, Callistris glaucophyllia, Melaleuca spp. and Thyptomine calycina, were assayed for in vitro antibacterial activity. M. alternifolia was also included for comparison purposes. Activity was determined using standard disc diffusion assays with each oil assayed at 100%, 10% and 1% against five bacteria (Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, Pseudomonas aeruginosa and Alcaligenes faecalis) and the yeast, Candida albicans. All bacteria, with the exception of Ps. aeruginosa, were susceptible to one or more of the essential oils at 100%, with only Eremophilia mitchelli inhibiting the growth of any bacteria at 1% (inhibition of Sal. typhimurium). Where multiple samples of a single oil variety were tested variability in activity profiles were noted. This suggests that different methods of preparation of essential oils, together with variability in plant chemical profiles has an impact on whether or not the essential oil is of use as an antimicrobial agent. These results show that essential oils from Australian plants may be valuable antimicrobial agents for use alone or incorporated into cosmetics, cleaning agents and pharmaceutical products.
Double-blinding is an important and widely implemented feature of clinical trials although its success is rarely assessed. In a randomized, placebo-controlled trial of tea tree oil, an aromatic essential oil, for the treatment of recurrent herpes labialis (RHL), or cold sores, deception was used to prevent volunteers from identifying their treatment allocation. Volunteers received placebo (n=102) or tea tree oil (n=112) ointment in preparation for their next episode of RHL and were told, falsely, that the aroma of the ointments had been changed to prevent identification of the treatment group. At the trial's end, of the volunteers who had used their ointment and presented for treatment assessment (n=100), approximately 50% correctly guessed their treatment allocation (P=0.774). Amongst volunteers that had not presented for treatment assessment (n=114), 12 volunteers did not provide blinding data and 46 did not open their tube. For the 56 volunteers who opened their tube, less than half of those receiving tea tree oil (44.4%) and only a small proportion of those on placebo (17.2%) were able to correctly identify their treatment allocation. Among the volunteers that were not treated, the P-value was 0.083. This study showed that the ethical use of deception may provide effective blinding in challenging circumstances.