Melaleuca Alternifolia Essential Oil Research Articles

Nonlinear viscoelasticity of Melaleuca alternifolia essential oil Pickering emulsion stabilized with cellulose nanofibrils

Pickering emulsions are suitable technological approaches to stabilize the bioactive compounds of essential oils (EOs) with economic interests for the pharmaceutical, cosmetic and food industries using atoxic and renewable stabilizers, such as cellulose nanostructures. The Melaleuca alternifolia essential oil (MaEO) is recognized for its pronounced antimicrobial performance, which has attracted your interest in developing eco-friendly antiseptic products. In this contribution, we report the nonlinear viscoelasticity behavior of MaEO-in-water Pickering emulsions stabilized by cellulose nanofibrils (CNF) using Large Amplitude Oscillatory Shear (LAOS) tests. The rheological characterizations by Fourier Transform (FT) rheology spectroscopy and Lissajous plots enabled the correlation of the viscous and elastic behaviors with the physical processes involving the deformation of the emulsion. Also, the internal structure of the emulsion was elucidated by fluorescence optical microscopy. Several findings relative to the effects of the shear deformation amplitude over the nonlinear viscoelasticity of the emulsified system are reported here, which are essential to the industrial processes used to develop technological products.

The influence of plant scents on nest box inspection by Eastern Rosella (Platycercus eximius)

ABSTRACT Many cavity nesters add volatile plants with medicinal properties to their nests. In Australia, eucalyptus and tea-trees are highly volatile plants, which have antiparasitic and antimicrobial properties. Here, we tested whether scents of eucalypt (Eucalyptus polybractea) and tea tree (Melaleuca alternifolia) essential oils can attract birds to newly installed nest boxes. Twenty-four nest boxes received three scent treatments (eucalypt, tea tree, control) for 10 days each using a Latin-square design. Bird visitation was recorded using camera traps. Eastern Rosellas (Platycercus eximius) visited the nest boxes the most (1,454 visits) and were therefore the focus of the study. Eastern Rosellas did not change their behaviours in response to the eucalypt scent in nest boxes: there was no difference in visitation, duration of visits or nest box inspection behaviour between nest boxes with eucalypt scent and those with the control scent. However, Eastern Rosellas visited nest boxes with tea tree scent less frequently and spent less time at these boxes than those with the control scent. The mean time that Eastern Rosellas spent inspecting boxes slightly increased over the 10-day period following scent placement at boxes with control and eucalypt scents, while it sharply decreased at boxes with tea tree scent. This is the first study demonstrating that an Australian bird detected and behaved differently in response to plant volatiles. The use of scents may offer opportunities to not only attract, but potentially also deter certain birds from using particular hollows.

The essential oil of Melaleuca alternifolia incorporated into hydrogel induces antimicrobial and anti-inflammatory effects on infected wounds by Staphylococcus aureus

Staphylococcus aureus is one of the most common bacterial isolates found in wounds. Thus, innovative dressings, such as hydrogels, are interesting vehicles for incorporating bioactive compounds like those from Melaleuca alternifolia essential oil (MaEO). In this study, we evaluated the antimicrobial and anti-inflammatory potential of MaEO incorporated into an alginate and chitosan hydrogel for treating wounds infected by S. aureus. The hydrogel incorporated with MaEO 1% (HMa 1%) was homogeneous with a bright pale-yellow color and the characteristic smell of Melaleuca. The incorporation of MaEO 1% does not affect the stability of the hydrogel, which was stable up to 90 days of storage. The Scanning electron microscopy analysis revealed that hydrogels showed irregular surfaces and interconnected porous structures with accumulations of oil crystals distributed throughout the formulation. HMa 1% has a high moisture content (95.1%) and can absorb simulated wound fluid. Regarding the antimicrobial effects, HMa 1% reduced the growth of S. aureus ATCC 6538 in both in vitro conditions and in an ex vivo model of wounds using porcine skin. In addition, the dairy topical treatment of murine skin lesions with HMa 1% induced a significant reduction of the wound area, inflammation score, and bacterial load, as well as tissue re-epithelialization and modulation of inflammatory mediators. Therefore, hydrogel incorporated with MaEO 1% has excellent potential to be used in the pharmacotherapy of infected wounds.

Laboratory assessment of the acaricidal, repellent and anti-cholinesterase effects of Melaleuca alternifolia and Chamaemelum nobile essential oils against Hyalomma scupense ticks.

In cattle, Hyalomma scupense serves as an important vector of several pathogens resulting in diseases, subsequently affecting the agricultural field as well as the economy. Resistance to chemical acaricides has become widespread affirming the need for new drugs to tick control. The goal of this study was to investigate the acaricidal, repellent activities as well as the putative mode of action of two essential oils (EOs) from Melaleuca alternifolia (Tea tree) and Chamaemelum nobile (Roman chamomile) on Hyalomma scupense. The chemical composition of EOs was also evaluated. Different concentrations of EOs were tested in vitro for their acaricidal property on adults and larvae of H. scupense using adult immersion test (AIT) and larval packet test (LPT). Additionally, using Ellman's spectrophotometric method, the anticholinesterase (AChE) inhibition activity of M. alternifolia and C. nobile EOs was assessed in order to understand their putative mode of action. The main compounds of C. nobile were α-Bisabolene (22.20%) and (E)-β-Famesene (20.41%). The major components in the analyzed M. alternifolia were Terpinen-4-ol (36.32%) and γ-Terpinene (13.69%). Adulticidal and larvicidal assays demonstrated a promising efficacy of the essential oils against tick H. scupense. The lethal concentration (LC50) values obtained for M. alternifolia and C. nobile oils were 0.84 and 0.96 mg/mL in the AIT and 0.37 and 0.48 mg/mL in the LPT, respectively. Regarding repellent activity, M. alternifolia achieved 100% repellency at the concentration of 1 mg/mL while C. nobile showed 95.98% repellency activity at concentration of 4 mg/mL. Also, M. alternifolia and C. nobile EOs displayed potent AChE inhibition with IC50 value of 91.27 and 100.12 μg/mL, respectively. In the present study, M. alternifolia and, to a lesser degree, C. nobile EOs were found to be effective in vitro acaricides, repellents and acetylcholinesteraseinhibitor against H. scupense ticks. These plants may represent an economical and sustainable alternative to toxic synthetic acaricides in the management of ectoparasites of veterinary importance.

Nanoemulsions and nanocapsules loaded with Melaleuca alternifolia essential oil for sepsis treatment.

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.

An upcycled fraction of Melaleuca alternifolia essential oil regenerates the skin through the skin melatonin pathway and improves sleep quality.

Sleep is one of the most important factors affecting overall health. During the night, the skin repairs damage caused by daily stresses. Melatonin plays a key role in this process. Toxins are removed, and cellular repair and growth hormone production are increased. Inter alia, this also decreases signs of intrinsic aging. The current study was intended to demonstrate the impact of a unique fraction of Melaleuca alternifolia (FMA) essential oil, on sleep and skin quality. The effect of FMA was investigated invitro on skin cells, evaluating its antioxidant and anti-inflammatory properties, and in an ex-vivo study on human skin biopsies treated with FMA following stress induction. In addition, two clinical studies were performed on volunteers with life-style-related sleep complaints. In one study, sleep was measured using a noncontact monitoring device (SleepScore Labs, Max). A second study was conducted to assess skin anti-aging effects. In vitro application of FMA reduced IL-8 and reactive oxygen species (ROS) generation in skin cells. This was confirmed exvivo through a decrease in inflammatory markers and an increase in antioxidant enzymes after stress induction. Interestingly, FMA also upregulated melatonin-associated genes. Real-world sleep tracking revealed that FMA significantly improved sleep quality, relative to unscented control. Invivo applications also showed a reduction in signs of aging. These results provide initial data to suggest that this unique FMA delivers skin anti-aging benefits via a two-pronged mode of action, improving sleep quality, and reducing skin inflammatory and oxidative stress.

Microbioma intestinal e morfometria de codornas alimentadas com dietas contendo óleos essenciais

ABSTRACT: One of the greatest challenges in poultry production is maintaining intestinal mucosal barrier integrity and gut microbiota balance. Safe alternative antimicrobials that can regulate the microbial community through animal feed have been the subject of research in poultry production. This study evaluated the effect of Mentha piperita and Melaleuca alternifolia essential oils (EOs) on the gut microbiome and morphometry of broiler quails under normal feeding conditions. The gut microbiome was studied using a completely randomized design consisting of 4 treatments, namely control, bacitracin zinc, and the Eos M. piperita and M. alternifolia, with 8 repetitions and 7 quails per treatment, totaling 224 quails from 1 to 42 days old. The intestinal contents of the slaughtered quails were collected to evaluate the gut microbiome profile of their digestive tract. Gut morphometry was analyzed using a completely randomized factorial design, with four experimental rations for three intestinal sections (4x3) and five replications. The variables studied were villus surface area and height, crypt depth, villus height to cryptdepth ratio (VH:CD), villus-crypt ratio (V:C), villus width to height ratio (VW:H), and height of the intestinal epithelium and musculature. M. alternifolia (50 mg/kg of feed) in the diet of broiler quails improved gut morphometry, similar to the results obtained with bacitracin zinc. This EO also altered the gut microbiome of quails and reduced pathogenic bacterial diversity.

Effectiveness of Tea Tree (Melaleuca alternifolia) Essential Oil and Jojoba Carrier Oil through Topical Application on the Relief of Allergies Caused by Aeroallergens

Background: Allergies are one of the most common chronic conditions worldwide. Due to the cost and possible side effects of pharmacologic treatments, aromatherapy, an alternative method in relieving allergies was studied. Objective: This study aimed to determine the effectiveness of Jojoba Oil and 100% Tea Tree Essential Oil combination through topical application as an alternative method for relieving severity and frequency of allergic symptoms triggered by aeroallergens. Methods: A pre-experimental one-group pre-test and post-test research design was used to determine whether the combination of Tea Tree and Jojoba Oil produced an effect to the respondents’ allergic signs and symptoms. A modified 3-part questionnaire was used to gather data from thirty (30) purposively selected college students. Results: It appeared that the combination oil when applied topically resulted to a reduction in the severity and frequency of the allergic symptoms; specifically watery eyes, nasal congestion, runny nose, nasal itching, sneezing, coughing, chest tightness, wheezing, shortness of breath and phlegm production. The observed alleviation of symptoms is deemed significant with P-values less than 0.05, except for the reduction in the frequency of wheezing (P-value=.101>0.05) and shortness of breath (P-value=.053>0.05) nonetheless. Conclusion: Hence, the combination oil composed of Tea Tree essential oil with 2% dilution and Jojoba carrier oil when applied topically to the hot spots of the body reduces allergic symptoms. Nurses and other public healthcare providers can consider aromatherapy in the treatment regimen of individuals who have allergies but prefers to manage it non-pharmacologically or does not have access to anti-allergy medications.

ACOMPARATIVE STUDY OF ANTIMICROBIAL ACTIVITY OF MELALEUCA ALTERNIFOLIA,ACHILLEA MILLEFOLIUMAND CINNNAMOMUM CAMPHORAVAGINAL SUPPOSITORIES

Vaginal inflammation represents a heterogeneous group of disorders caused by infection, inflammation, or disruption of vaginal microflora. The most common causes of vaginal infection are Staphylococcus aureus, Enterococcus faecalis, Streptococcus agalactiae, Escherichia coliand Candida albicans. Antibiotic resistance is a major global problem, which can be mitigated by using natural antimicrobial substances such as essential oils. Each essential oil has an extremely complex composition (some essential oilshave over 200 components), which prevents microorganisms from developing resistance. Therefore, essential oils retain their effects.The aim of our study was to investigate antibacterial activity Melaleuca alternifolia, Achillea millefoliumand Cinnamomumcamphoravaginal suppositories, and see which essential oil has the strongest potential to be used as active ingredient for vaginal infections.The antimicrobial activity of the vaginal suppositories was examined using the disk diffusion method. Standard bacterial strains were used for the ATCC collection: Staphylococcus aureus (S. aureus) ATCC 25923, Enterococcus faecalis (E. faecalis)ATCC 51299, Escherichia coli (E. coli)ATCC 25922, Candida albicans (C. albicans)ATCC 10231.The results showed that Melaleuca alternifolia essential oil has an antimicrobial effect on all tested strains, with the strongest effect on Candida albicans(ZI 22.7 mm). Achillea millefoliumessential oil had no effect on Enterococcus faecalis, whereas Cinnamomum camphoraessential oil did not show zones of inhibition of Candida albicans.KEYWORDS:vaginal suppository, Melaleuca alternifolia, Achillea millefolium, Cinnamomum camphora,antimicrobial activity

Insecticidal and Repellent Activities of Four Essential Oils Against Sitophilus zeamais (Coleoptera: Curculionidae).

This study aimed to evaluate the efficacy of Corymbia citriodora, Melaleuca alternifolia (Myrtaceae), Mentha × piperita (Lamiaceae), and Schinus terebinthifolius (Anacardiaceae) essential oils as an alternative to manage Sitophilus zeamais (Coleoptera: Curculionidae) adults. Acute contact toxicity, acute toxicity on treated maize grain, fumigation toxicity, repellency bioassays, and GC-MS analysis of the essential oils were carried out. Corymbia citriodora, M. alternifolia, M. × piperita, and S. terebinthifolius oils were toxic at different levels to S. zeamais through residual contact, ingestion and via fumigation, and were also repellent to adults of this pest. Melaleuca alternifolia oil was the most active in contact (LC50 = 18.98μL.mL-1), ingestion (LC50 = 1.03μL.g-1), and fumigant (LC50 = 20.05μL.L-1 air) bioassays. Citronelal (53.6% in C. citriodora), terpinen-4-ol (46.9% in M. alternifolia), menthol (44.8% in M. × piperita), and β-caryophyllene (16.2% in S terebinthifolius) are the major constituents of these oils. Melaleuca alternifolia and M. × piperita essential oils can be used by residual contact, while those of C. citriodora, M. alternifolia, and M. × piperita by mixing with maize grains. Melaleuca alternifolia essential oil can be used as a fumigant, while those of C. citriodora and S. terebinthifolius as repellents for S. zeamais adults.

Phase diagrams and property of colloidal systems prepared with an alkyl polyglucoside surfactant and the essential oil of Melaleuca alternifolia (tea tree)

BackgroundThe purpose of this study was to develop the colloidal formulation, based on microemulsions and hydrogels, of Melaleuca alternifolia oil (aka tea tree oil, TTO) using a sustainable and biocompatible alkyl polyglucoside (APG) surfactant, Glucopon 600 CSUP (G600), commonly formulated for personal-care and home-care products. MethodsThe pseudo-ternary phase diagram of TTO-mixed surfactant-water was established with the water titration method at 25 °C. The mixed surfactants were composed of G600 and propylene glycol (PPG) as a co-surfactant at G600/PPG = 1/1, 2/1 and 3/1 (m/m). Colloid samples of one phase were further characterized with rheological measurements and dynamic light scattering (DLS) at 25 °C. Significant findingsThe samples containing TTO/mixed surfactant = 1/9 (m/m) and water show single phase only. With increasing water contents, the aforesaid system changed from Newtonian to pseudo-plastic, reflecting the transition from micellar solution / microemulsion to hydrogel. Especially, the gel-like behavior was confirmed with the dynamic oscillatory measurements, in which storage moduli were always larger than loss moduli at any time and any frequency under a constant strain of 0.5 %. Microemulsions made of 1 wt% tea tree oil and 9 wt% mixed surfactants were stable for > 1 month as monitored by aggregate size by DLS.

Tea tree (Melaleuca alternifolia) Essential Oil Concentration in Microemulsion with Antibacterial and Antifungal Activity: An Overview

Abstract: The tea tree (Melaleuca alternifolia), a member of the Myrtaceae family, is a valuable medicinal and aromatic plant. Tea Tree essential oil (TTO) has many medical applications, including antibacterial, antifungal, antiviral, antiprotozoal, anti-inflammatory, antioxidant, and anticancer properties. Although the concentration of TTO in a microemulsion is of economic interest, very few studies on this product have been conducted. In this study, we look at how different tea tree oil concentrations in microemulsion formulations affect susceptibility to various bacteria and fungi. TTO susceptibility in a diverse range of microbial species has now been studied using data from a previously published literature review survey. Most bacteria are resistant to TTO at concentrations as low as 1.0 percent, but mucosal skin staphylococci and micrococci, Enterococcus faecalis, and Pseudomonas aeruginosa have minimum inhibitory concentrations much higher than 2 percent. TTO susceptibility in fungi has only recently been scrutinized. Fungicidal dosages range from 0.12 to 2 percent, with minimum inhibitory concentrations ranging from 0.03 to 0.5 percent and the only notable exception is Aspergillus niger, which contains fungicidal concentrations of up to 8%. The review emphasizes the importance of new antibacterial and antifungal formulations, as well as the role of natural essential oils in the discovery of new antibacterial and antifungal agents, and discusses, in brief, all constituents derived from the essential oil (tea tree) that are in preclinical and clinical development. This paper summarizes human and food-borne bacteria and fungi susceptibility to tea tree essential oils and their constituents. Among the many tested, essential oils of spices and herbs (Melaleuca alternifolia) were found to have the strongest antimicrobial properties. This review looks at a wide range of scientific literature, including Sci-hub, Google Scholar, Pub, Chem, NCBI, and web books.

Insecticidal and antifeedant bioactivities of Melaleuca alternifolia essential oil on Ascia monuste orseis

This study evaluated the bioactive effects of Melaleuca alternifolia essential oil on the behavior and mortality of Ascia monuste orseis caterpillars. The experiment was conducted at the laboratory under controlled conditions using a completely randomized design with six treatments, represented by A. monuste orseis caterpillars fed collard leaves treated with 0 (control), 5, 10, 20, 30, or 40 mg mL−1 essential oil. Each treatment consisted of five replicates of four third-instar caterpillars. Mean daily intake of collard leaves, feces production, mortality, and behavioral changes were assessed for 15 days after the beginning of the experiment. Data on leaf intake and feces production were subjected to analysis of variance by the F-test; when significant differences were found, data were subjected to regression analysis. Corrected mortality rate was calculated and subjected to analysis of variance by the F-test followed by Tukey’s test at the 5% significance level for comparison of means. The median lethal dose (LD50) was also evaluated. Two very clear feeding behaviors were observed, one in caterpillars exposed to essential oil concentrations of 5, 10, and 20 mg mL−1, which showed little difference in feed intake from the control, and the other in caterpillars exposed to the highest concentrations (30 and 40 mg mL−1), which showed a decrease of 76 to 93% in feed intake compared with the control. Lower leaf intake resulted in a decrease in feces production, and the negative effects increased linearly with essential oil concentration. The mortality curve showed a linear and positive response to essential oil concentration, reaching 100% in insects exposed to the highest concentrations. The LD50 was 13.93 mg mL−1.

Eco-friendly and effective antimicrobial Melaleuca alternifolia essential oil Pickering emulsions stabilized with cellulose nanofibrils against bacteria and SARS-CoV-2

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.

In Vitro Antifungal Activity of Selected Essential Oils Against Trichophyton mentagrophytes

Abstract The in vitro activity of Cinnamomum cassia, Melaleuca alternifolia, and Cymbopogon citratus essential oils and antimycotics clotrimazole, fluconazole, and ketokonazole against T. mentagrophytes was evaluated by the disc-diffusion method. The essential oils were tested at 5, 10, 20, 30, 50, and 100 % concentration. It was found that Cymbopogon, commonly called lemongrass, and cinnamon show stable results independent of the concentration used, whereas the efficacy of tea tree oil, significantly decreases with the decreasing concentration. When comparing the efficacy of antimycotics the largest zone of inhibition was obtained with clotrimazole, while fluconazole proved to be ineffective. We found that cinnamon and lemongrass are more effective than the antimycotics that we have used. Our study confirmed that some essential oils can be used for the treatment of dermatophytoses caused by Trichophyton mentagrophytes and some of them are more effective than the commercial drugs.

Anthelmintic effects of peppermint (Mentha piperita), lemon (Citrus limon), and tea tree (Melaleuca alternifolia) essential oils against Monogenean parasite (Dactylogyrus sp.) on carp (Cyprinus carpio).

Dactylogyrus sp. (Monogenea) is one of the most dangerous pathogens causing parasitic infections in carp (Cyprinus carpio) and other freshwater fish. Due to the adverse effects of conventional chemical treatments on the environment and fish, the use of herbal products in aquaculture against various diseases has increased. In the present study, anthelmintic effects of peppermint (Mentha piperita), lemon (Citrus limon), and tea tree (Melaleuca alternifolia) essential oils against Dactylogyrus sp. found on the gills of carp were studied using in vitro and in vivo experiments. In in vitro experiments, 1, 2.5, 5, and 10 μl/ml concentrations of these essential oils were tested on the parasites and cumulative mortalities were observed to reach 100 % after treatment with peppermint, lemon, and tea tree essential oils of 1 μl/ml concentration in approximately 15, 10 and 2 min, respectively. The in vitro experiments demonstrated that the cumulative mortality of the parasites increased with essential oil concentration and exposure duration. As the concentration of essential oil used increased, the observed mean time to death of parasites decreased. In in vivo experiments, median effective concentrations (EC50) as assessed by in vitro tests for peppermint and lemon essential oils in 5 min exposure and EC50 concentration for tea tree essential oil in 2 min exposure was applied on fish as a single bath and there was a significant decrease in the mean parasite intensities (p<0.05). Antiparasitic efficacies of peppermint, lemon, and tea tree essential oils were determined as 28.23 %, 30.95 %, and 35.31 %, respectively. The tea tree oil was the most effective and peppermint oil was the least effective in both in vitro and in vivo experiments. All three herbal essential oils tested in this study have weak antiparasitic potential against monogenean infections in fish.

Antifungal Potential of Melaleuca alternifolia against Fungal Pathogen Fusarium oxysporum f. sp. cubense Tropical Race 4.

Fusarium wilt of bananas caused by Fusarium oxysporum f. sp. cubense Tropical Race 4 (Foc TR4) poses the most serious threat to banana production globally. The disease has been managed using chemical fungicides, yet the control levels are still unsatisfactory. This study investigated the antifungal activities of tea tree (Melaleuca alternifolia) essential oil (TTO) and hydrosol (TTH) against Foc TR4 and their bioactive components. The potential of TTO and TTH in inhibiting the growth of Foc TR4 was evaluated in vitro using agar well diffusion and spore germination assays. Compared to the chemical fungicide, TTO effectively suppressed the mycelial growth of Foc TR4 at 69%. Both the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of TTO and TTH were established at 0.2 µg/µL and 50% v/v, respectively, suggesting the fungicidal nature of the plant extracts. The disease control efficacies were also demonstrated by a (p ≤ 0.05) delayed Fusarium wilt symptom development in the susceptible banana plants with reduced LSI dan RDI scores from 70% to around 20-30%. A GC/MS analysis of TTO identified terpinen-4-ol, eucalyptol, and α-terpineol as the major components. In contrast, an LC/MS analysis of TTH identified different compounds, including dihydro-jasmonic acid and methyl ester. Our findings indicate the potential of tea tree extracts as natural alternatives to chemical fungicides to control Foc TR4.

Synergistic Inhibition of Methicillin-Resistant Staphylococcus aureus (MRSA) by Melaleuca alternifolia Chell (Tea Tree) and Eucalyptus globulus Labill. Essential Oils in Association with Oxacillin.

The presence of antibiotic-resistant bacteria has become a major therapeutic priority. This trend indicates the need for alternative agents to antibiotics, such as natural compounds of plant origin. By assessing membrane permeability, we investigated the antimicrobial activity of Melaleuca alternifolia and Eucalyptus globulus essential oils (EOs) against three strains of methicillin-resistant Staphylococcus aureus (MRSA). Using the checkerboard method, the efficacy of single EOs, in association with each other or in combination with oxacillin, was quantified by calculating the fractional inhibitory concentrations (FIC Index). All EOs showed a reduction in bacterial load, an alteration of membrane permeability which leads to an increase in its function, resulting in the release of nucleic acids and proteins. The treatment with EO-oxacillin combinations and associated EO-EO resulted in a synergistic effect in most of the tests performed. EO-EO association showed a high activity in the alteration of the membrane, increasing the permeability to about 80% in all the MRSA strains treated. In conclusion, the combination of EOs and antibiotics represents a valid therapeutic support against MRSA bacteria, allowing for a decrease in the antibiotic concentration needed for therapeutic use.

Use of Melaleuca alternifolia essential oil as an efficient strategy to extend the shelf life of banana fruits

Banana anthracnose is one of the main postharvest diseases economically compromising the fruit production chain. Fruit treatment with natural products can reduce postharvest pathogen infestation and increase protection during storage. For natural control of this disease, the activity of the essential oil of Melaleuca alternifolia (MAEO) was investigated in Colletotrichum musae. The aim of this study was to evaluate the in vitro antifungal activity of the MAEO on C. musae by of different concentrations and to evaluate the effect of MAEO on the incidence and severity of anthracnose. The essential oil (EO) was characterized by gas chromatography (GC-FID and GC-MS). The relative percentage of monoterpenes was 96.94%, and terpinen-4-ol was the main component (47.08%). The minimum inhibitory dose (EC100) of the mycelial growth of C. musae was reached at a concentration of 2.15 μg mL−1. Bananas were treated with water emulsions MAEO into at different concentrations (0.50, 1.00, 2.00, 3.00, 4.00 and 5.00 μg mL−1) for 08 days of storage at 25 ± 2 °C. MAEO showed fungistatic action from the concentration of 2.0 μg mL−1 (p < 0.05). The results showed that, after storage, MAEO at 0.50, 1.00, 2.00, 3.00, 4.00 and 5.00 μg mL−1 reduced area under the disease-progress curve (AUDPC) by 80%, 90%, 95%, 96%, 97% and 98%, respectively. MAEO reduces the severity of anthracnose after fruits treatment, without causing phytotoxic action, maybe a promising candidate for Biorational pesticides, in preservation and increment shelf life fruits banana.

Optimizing the Antimicrobial Synergism of Melaleuca alternifolia (Tea Tree) Essential Oil Combinations for Application against Respiratory Related Pathogens.

Antimicrobial research into the use of Melaleuca alternifolia essential oil has demonstrated broad-spectrum activity; however, much of the research published focuses on identifying the potential of this essential oil individually, rather than in combination for an enhanced antimicrobial effect. This study aimed to determine the antimicrobial activity of four essential oil combinations, all inclusive of M.alternifolia, against nine pathogens associated with the respiratory tract. The minimum inhibitory concentration assay was used to determine the antimicrobial activity of four essential oil combinations, M.alternifolia in combination with Cupressus sempervirens, Origanum majorana, Myrtus communis, and Origanum vulgare essential oils. The interactions between essential oil combinations were analyzed using isobolograms and SynergyFinder 2.0 software to visualize the synergistic potential at varied ratios. The antimicrobial activity of the different combinations of essential oils all demonstrated the ability to produce an enhanced antimicrobial effect compared to the essential oils when investigated independently. The findings of this study determined that isobolograms provide a more in-depth analysis of an essential oil combination interaction; however, the value of that interaction should be further quantified using computational modelling such as SynergyFinder. This study further supports the need for more studies where varied ratios of essential oils are investigated for antimicrobial potential.