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Simple Summary: The implications of intestinal barrier function improvement in immune-stressed weaning piglets by terpinen-4-ol(TER) are observed. Enhanced nutrient absorption, reduced gastrointestinal disease incidence, and improved overall growth performance can be achieved through improved intestinal barrier function. A promising alternative is offered by the use of TER as a natural plant extract. Far-reaching implications on animal health, economic viability, environmental sustainability, and animal welfare are observed from the use of TER to improve intestinal barrier function in immune-stressed weaning piglets. The importance of natural alternatives in enhancing livestock productivity and health is underscored by this promising approach, paving the way for more sustainable and ethical farming practices. The aim of this study was to investigate the effects of terpinen-4-ol (TER) supplementation on the intestinal barrier function of pigs. Five groups of fifty 28-day-old piglets with comparable body weights were randomly assigned to the following groups: the control group (CON), the lipopolysaccharide group (LPS), the low TER group (PLT), the middle TER group (PMT), and the high TER group (PHT). The basal diet was given to the CON and LPS groups, and 30, 60, or 90 mg/kg TER was added to the basal diet for the TER groups. After the 21-day trial period, piglets in the LPS and TER groups received an intraperitoneal injection of 100 μg/kg body weight of LPS, whereas the piglets in the CON group received an injection of 0.9% normal saline solution. The results showed that LPS stimulation resulted in a decrease (p < 0.05) in the depth of colonic crypts in piglets, which was greater (p < 0.05) in the TER group. Compared with those in the CON group, the number of goblet cells and MUC2 expression were decreased in the colon of piglets in the LPS group, while these parameters were increased in the PMT group (p < 0.05). The malondialdehyde (MDA) content was greater in the colon of the LPS group than in that of the CON group, while the activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and catalase (CAT) were lower in the colon of the LPS group; conversely, the MDA content was lower in the colons of the PLT and PMT groups than in those of the LPS group (p < 0.05). TER also reduced (p < 0.05) LPS-induced upregulation of IL-1β and TNF-α expression, along with the relative gene expression of NLRP3, ASC, and caspase-1 in the colon of piglets (p < 0.05). Compared with those in the CON group, the abundances of Firmicutes and UCG-005 in the LPS group were lower (p < 0.05), and those in the TER group were significantly greater than those in the LPS group. Compared with those in the CON group, the abundance of Proteobacteria in the LPS group increased (p < 0.05), while the abundance of Actinobacteria and Phascolarctobacterium increased (p < 0.05) in the colon of the PHT group compared with that in the LPS group. In conclusion, TER effectively improved the intestinal barrier function of the colon in weaning piglets. Based on the results of this study, the appropriate dose of TER in the diets of weaning piglets was 60 mg/kg. [ABSTRACT FROM AUTHOR]

Tea tree oil (TTO), acquired from Melaleuca alternifolia (Maiden & Betche) Cheel, Myrtaceae, is a widely utilized essential oil (EO) due to its bioactive properties. The identification and quantification of TTO ingredients is generally performed by GC-MS, which provides the most accurate results. However, in some instances, the cost and time of analysis may pose a challenge. Thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC) offer a simpler, faster, cost-effective alternative capable of simultaneously analyzing and quantifying multiple samples. In addition, for more complex oils, two-dimensional (2D) or multigradient development (MGD) TLC provide better separation. Nevertheless, further development is sometimes necessary for the isolation of comigrating components. This study showcases a combined 2D-MGD TLC/HPTLC method for the successful separation of TTO components of interest. While human error, limited separation, and the partial evaporation of volatile components may still present a challenge during the process, considerable recovery of mono- and sesquiterpenes was achieved. This protocol also resulted in the successful isolation of target oxygenated monoterpenes (OMs) producing highly pure terpinen-4-ol (100%) and α-terpineol (≥94%), confirmed by GC-MS. The accurate enantiomeric distribution of these major OMs was verified by GC-FID through the use of a chiral cyclodextrin-based stationary phase. The observed positive enantiomer range (area percent) as well as (+)/(−) ratio for each terpinen-4-ol and α-terpineol were within acceptable ISO criteria. [ABSTRACT FROM AUTHOR]

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of tea tree oil obtained from leaves and terminal branchlets of Melaleuca alternifolia (Maiden & Betche) Cheel when used as a sensory additive for all animal species. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that tea tree oil was very unlikely to be of safety concern for long‐living and reproductive animals and is of no concern for target species for fattening at the following concentrations in complete feed: 1.1 mg/kg for chickens for fattening, 1.5 mg/kg for turkeys for fattening, 1.7 mg/kg for laying hens, 2.0 mg/kg for piglets, 2.4 mg/kg for pigs for fattening, 3.1 mg/kg for sows, 5.0 mg/kg for veal calves (milk replacer) and salmonids, 4.4 mg/kg for cattle for fattening, sheep/goats and horses, 2.9 mg/kg for dairy cows, 1.8 mg/kg for rabbits, 0.9 mg/kg for cats, 5.3 mg/kg for dogs, 6.6 for crustaceans and 15 mg/kg for ornamental fish. These conclusions were extrapolated to other physiologically related species. For any other species, the additive is very unlikely to be of safety concern at 1.1 mg/kg complete feed. No concerns for consumers and the environment were identified following the use of the additive up to the highest safe use level in feed. Regarding user safety, tea tree oil should be considered as an irritant to skin and eyes and as a dermal and respiratory sensitiser. It is classified as a reprotoxic substance (category 1B) following CLP criteria and should be handled accordingly. Since M. alternifolia and its preparations were recognised to flavour food and its function in feed would be essentially the same as that in food, no further demonstration of efficacy was considered necessary. [ABSTRACT FROM AUTHOR]

Hydrolates or floral waters are the outcomes of the hydrodistillation of aromatic plants. The production of hydrolates is simple and affordable because they are byproducts of the essential oil. The composition and biological activities of hydrolates may differ from those of the corresponding essential oils. The main objective of the study was to assess the chemical profile of the volatiles extracted from the hydrolate obtained from the aerial part of Origanum vulgare L., but also to evaluate the anti-inflammatory and antioxidant activity of the hydrolate obtained from the aerial part of Origanum vulgare. Qualitative and quantitative analyses of the extracted volatiles, performed using gas chromatography/mass spectrometry (GC/MS) and gas chromatography/flame ionization detection (GC/FID), showed that the main components were terpinen-4-ol (36%) and 1-octen-3-ol (33.6%). At all concentrations tested, the hydrolate scavenged 1,1-diphenyl-2 picrylhydrazyl (DPPH) radicals in a way that depended on concentration and showed antioxidant activity in the ß-carotene/linolenic acid assay. The total antioxidant capacity of oregano hydrolat was calculated using Ferric Reducing Antioxidant Power Assay (FRAP assay), which resulted in a FRAP value of 0.361 ± 0.015 µmol Fe2+/ml. In addition to antioxidant activity, satisfactory anti-inflammatory activity was also observed with the percentage inhibition of BSA denaturation of 71.2 ± 0.006%. Demonstrated antioxidant and anti-inflammatory properties of O. vulgare hydrolate may be crucial to its future and use in many industrial fields. [ABSTRACT FROM AUTHOR]

To investigate the therapeutic effect of metronidazole gel combined with terpinen-4-ol on demodex blepharitis. Methods: 100 patients (100 eyes) with demodex blepharitis were divided into control group and study group according to the random number table method, 50 cases (50 eyes) in each group. Control group was treated with terpinen-4-ol cotton tablets, and study group was treated with metronidazole gel on the basis of control group. The changes of demodex mites microscopic examination counts, eye symptoms (itching, dryness, foreign body sensation, blurred vision) score, ocular surface related score [ocular surface disease index (OSDI) score, meibomian gland opening score], tear film stability index [tear film breakup time (BUT), corneal fluorescein staining (FL) score] were observed before and after treatment in two groups. Results: 1 month after treatment and 3 months after treatment, the demodex mites microscopic examination counts in two groups decreased, and study group was lower than that of control group at the same time point (P<0.05). 1 month after treatment and 3 months after treatment, the scores of eye itching, dryness, foreign body sensation, blurred vision, OSDI, meibomian gland opening and FL in two groups decreased, and study group were lower than those of control group at the same time point (P<0.05). 1 month after treatment and 3 months after treatment, BUT increased, and study group was higher than that of control group at the same time point (P<0.05). Conclusion: The curative effect of metronidazole gel combined with terpinen-4-ol in the treatment of demodex blepharitis is significant, which can strengthen the effect of mite removal, improve the stability of tear film and effectively reduce the eye symptoms of patients. [ABSTRACT FROM AUTHOR]

Manuka oil and tea tree oil are essential oils with known antibacterial properties that are believed to be caused by one main component: terpinen-4-ol. Terpinen-4-ol has potent antibacterial activity against caries-related microorganisms. However, few studies have investigated the antimicrobial effects of terpinen-4-ol on bacteria in apical periodontitis. Thus, the objective of the present study was to evaluate the antibacterial and antibiofilm potential of terpinen-4-ol against Enterococcus faecalis , Porphyromonas gingivalis , Prevotella intermedia , and Fusobacterium nucleatum , which have all been detected in apical periodontitis. The minimum inhibitory and minimum bactericidal concentrations of terpinen-4-ol were determined to assess its activity against biofilms. The minimum inhibitory concentration of terpinen-4-ol was 0.25% against E. faecalis and F. nucleatum , 0.05% against P. gingivalis , and 0.1% against P. intermedia. The minimum bactericidal concentration of terpinen-4-ol was 1.0% against E. faecalis , 0.2% against P. gingivalis and P. intermedia , and 0.5% against F. nucleatum. In the biofilm evaluations, all terpinen-4-ol-treated bacteria had significant reductions in biofilm viability compared with controls in experiments assessing attachment inhibitory activity. Furthermore, structural alterations and decreased bacterial cell clumping were observed under scanning electron microscopy, and significantly decreased cell survival was noted using fluorescence microscopy. Together, these results suggest that terpinen-4-ol is a potential antibacterial agent with bactericidal properties, and can also act on established biofilms. [ABSTRACT FROM AUTHOR]

BACKGROUND: Terpinen-4-ol has been found to have a significant antibacterial activity against pathogenic bacteria associated with peri-implantitis and can reduce the formation of surface biofilm and the occurrence of peri-implantitis when applied to the surface of titanium implants; however, the studies regarding its biosafety are lacking. OBJECTIVE: To explore the antibacterial effects of terpinen-4-ol on Staphylococcus aureus and Streptococcus mutans and its effect on the growth and osteogenic differentiation of MC3T3-E1 cells. METHODS: Different concentrations of terpinen-4-ol were dissolved in dimethyl sulfoxide. The minimum inhibitory concentration and minimum bactericidal concentration of pineolene 4 alcohol solution against Staphylococcus aureus and Streptococcus mutans were tested. The 1/2 minimum inhibitory concentration, minimum inhibitory concentration, and minimum bactericidal concentration of pineolene 4 alcohol were tested by bacteriostatic zone test. MC3T3-E1 cells were treated with different concentrations (0%, 0.3%, 0.2%, 0.1%, v/v) of terpinen-4-ol in medium or calcification-inducing solution. The proliferation activity of cells was detected by CCK-8 assay. Cells were stained with rhodamine-phalloidin to observe cytoskeleton. Differentiation ability of cells was detected by alkaline phosphatase activity assay. The formation of mineralized nodules was observed by alizarin red staining. The mRNA expression of Runx2 and osteocalcin was detected by real-time reverse transcription-polymerase chain reaction. RESULTS AND CONCLUSION: (1) Minimum inhibitory concentration and minimum bactericidal concentration of terpinen-4-ol against Streptococcus mutans were 0.1% (v/v) and 0.4% (v/v) respectively and against Staphylococcus aureus were 0.03% (v/v) and 0.125% (v/v) respectively. With the increase of the concentration of terpinen-4-ol, the diameter of bacteriostatic zone was significantly increased (P < 0.05). (2) CCK-8 assay showed that terpinen-4-ol promoted the proliferation of MC3T3-E1 cells, with the most obvious effects in the 0.2% group. (3) Rhodamine-phalloidin staining showed that terpinen-4-ol promoted the adhesion of MC3T3-E1 cells. (4) Alkaline phosphatase activity assay and alizarin red staining showed that terpinen-4-ol promoted the early differentiation and mineralization of MC3T3-E1 cells, with the most obvious effects in the 0.2% group. (5) Real-time reverse transcription-polymerase chain reaction showed that the mRNA expression of Runx2 was significantly higher in the 0.3%, 0.2%, and 0.1% groups than in the 0% group at 1 day of calcification induction (P < 0.05), and the mRNA expression of Runx2 and osteocalcin was significantly higher in the 0.2% and 0.1% groups than in the 0.3% and 0% groups at 7 and 14 days of calcification induction (P < 0.05). (6) These results indicate that terpinen-4-ol can inhibit the growth of Staphylococcus aureus and Streptococcus mutans and promote the proliferation, differentiation and mineralization of MC3T3-E1 cells. [ABSTRACT FROM AUTHOR]

According to previous research, turmeric seeds exhibit anti-inflammatory, anti-malignancy, and anti-aging properties due to an abundance of terpinen-4-ol (T4O). Although it is still unclear how T4O works on glioma cells, limited data exist regarding its specific effects. In order to determine whether or not glioma cell lines U251, U87, and LN229 are viable, CCK8 was used as an assay and a colony formation assay was performed using different concentrations of T4O (0, 1, 2, and 4 μM). The effect of T4O on the proliferation of glioma cell line U251 was detected through the subcutaneous implantation of the tumor model. Through high-throughput sequencing, a bioinformatic analysis, and real-time quantitative polymerase chain reactions, we identified the key signaling pathways and targets of T4O. Finally, for the measurement of the cellular ferroptosis levels, we examined the relationship between T4O, ferroptosis, and JUN and the malignant biological properties of glioma cells. T4O significantly inhibited glioma cell growth and colony formation and induced ferroptosis in the glioma cells. T4O inhibited the subcutaneous tumor proliferation of the glioma cells in vivo. T4O suppressed JUN transcription and significantly reduced its expression in the glioma cells. The T4O treatment inhibited GPX4 transcription through JUN. The overexpression of JUN suppressed ferroptosis in the cells rescued through T4O treatment. Taken together, our data suggest that the natural product T4O exerts its anti-cancer effects by inducing JUN/GPX4-dependent ferroptosis and inhibiting cell proliferation, and T4O will hope-fully serve as a prospective compound for glioma treatment. [ABSTRACT FROM AUTHOR]

Cytochrome P450 proteins (CYPs) in insects can encode various detoxification enzymes and catabolize heterologous substances, conferring tolerance to insecticides. This study describes the identification of a P450 gene (CYP6BQ8) from Tribolium castaneum (Herbst) and investigation of its spatiotemporal expression profile and potential role in the detoxification of terpinen-4-ol, a component of plant essential oils. The developmental expression profile showed that TcCYP6BQ8 expression was relatively higher in early- and late-larval stages of T. castaneum compared with other developmental stages. Tissue expression profiles showed that TcCYP6BQ8 was mainly expressed in the head and integument of both larvae and adults. The expression profiling of TcCYP6BQ8 in developmental stages and tissues is closely related to the detoxification of heterologous substances. TcCYP6BQ8 expression was significantly induced after exposure to terpinen-4-ol, and RNA interference against TcCYP6BQ8 increased terpinen-4-ol-induced larval mortality from 47.78 to 66.67%. This indicates that TcCYP6BQ8 may be involved in T. castaneum 's metabolism of terpinen-4-ol. Correlation investigation between the CYP6BQ8 gene and terpinen-4-ol resistance in T. castaneum revealed that the TcCYP6BQ8 gene was one of the factors behind T. castaneum 's resistance to terpinen-4-ol. This discovery may provide a new theoretical foundation for future regulation of T. castaneum. [ABSTRACT FROM AUTHOR]

The Mediterranean basin represents a rich source of medicinal and aromatic plants. These species contain different metabolites such as phenolics, flavonoids, tannins, coumarins and sterols known for their beneficial properties. The essential oils (EOs) of Lavandula austroapennina and Lavandula angustifolia from the Pollino massif (southern Italy) were characterized using gas chromatography-mass spectrometry and their anti-denaturation effect was assessed using in vitro models with heat-treated bovine serum albumin (BSA) chosen as a protein model. L. austroapennina EO showed a better in vitro anti-denaturation activity compared to L. angustifolia, with IC50 values equal to 260.4 ± 4.2 and 480.0 ± 2.6 µg/mL, respectively. In order to relate the observed results to the most interesting identified phytochemicals, some major components were also tested. Linalool and terpinen-4-ol proved to be effective in protecting BSA from heat denaturation. Moreover, the inhibitory properties on nitric oxide production were verified in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Both lavender EOs showed concentration-dependent inhibitory properties, as well as the monoterpene linalool. Taken together, these results suggest that L. austroapennina EO and its main constituent linalool could be good candidates for further investigations, aimed at finding new drugs with anti-arthritic potential. [ABSTRACT FROM AUTHOR]

The antimicrobial properties of essential oil from Lavandula sp. raise hopes related to its use in phytotherapy. This study aimed to evaluate the antimicrobial activity of essential oils from cultivars of L. angustifolia ('Hidcote Blue Strain', 'Hidcote Blue') and L. × intermedia ('Phenomenal', 'Grosso') grown in central-eastern Poland, that is, at the border of the northern lavender cultivation range. The chemical composition of the essential oils was determined by GC/MS. Essential oil concentrations (20, 10, 5, 2.5, 1.25, 0.6, 0.3, 0.16, 0.08, and 0.04 mg/mL) were tested to determine the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) or minimum fungicidal concentration (MFC) towards ten strains of Gram-positive bacteria, five Gram-negative bacteria, and eight yeasts in vitro culture. Essential oils from the Lavendula cultivars showed antimicrobial activity against all microorganisms analysed. The yeasts were characterised by higher sensitivity to lavender oil compared to bacteria, while Gram-positive bacteria were more sensitive than Gram-negative bacteria. The lowest MIC values for bacteria and fungi were obtained for 'Grosso'. Furthermore, the 'Grosso' oil showed the highest fungicidal activity, while the highest bactericidal activity was found in 'Hidcote Blue' and 'Grosso'. Using Staphylococcus aureus as an example, it was shown that different bacterial strains of the same species show varying sensitivity to the essential oil. A higher oil content was noted for the cultivars L. × intermedia, especially for the 'Phenomenal'. Linalyl acetate and linalool were the main components of the essential oil in all cultivars. However, in the 'Grosso' oil, a high content of terpinen-4-ol (18.08%) was also recorded. An analysis of the relationships between the content of the main components in the analysed essential oils and the antimicrobial activity of essential oils suggested that linalool and terpinen-4-ol were compounds potentially responsible for antimicrobial activity. The obtained results allow us to conclude that essential oil with significant antimicrobial activity can be obtained from Lavandula sp. plants harvested in the northern part of the cultivation range. [ABSTRACT FROM AUTHOR]

Origanum majorana is a medicinal and aromatic plant that belongs to the Lamiaceae family. It is cultivated in several parts of the world and, due to its splendid aroma and taste, is widely used for culinary purposes and in perfumes. The essential oil of the plant, to which is attributed its aroma, contains many secondary metabolites with valuable biological activity. One of them is the pesticide activity, which has attracted much interest. Given the necessity of replacing synthetic pesticides, essential oils are studied in an attempt to find naturally derived products. Thus, the aim of this review paper is to discuss the chemical profile of O. majorana essential oil and to present data regarding its insecticidal, repellent and fumigant activity. Data were collected from 1992 to 2022. Databases, including PubMed, Google Scholar, ScienceDirect and Scopus, were used for the research, and keywords, including O. majorana, sweet marjoram, essential oil, volatiles, pesticide, insecticide and repellent activity, were used. The results of this review paper indicate that O. majorana essential oil can be an alternative agent to manage pests. However, still, much research should be conducted to evaluate its toxicity against beneficial insects and to ensure its safety for human health. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance is a major public health issue raising growing concern in the face of dwindling response options. It is therefore urgent to find new anti-infective molecules enabling us to fight effectively against ever more numerous bacterial infections caused by ever more antibiotic-resistant bacteria. In this quest for new antibacterials, essential oils (or compounds extracted from essential oils) appear to be a promising therapeutic option. In the present work, we investigate the potential antibacterial synergy between a combination of terpinen-4-ol and α-terpineol (10:1) compared to standard tea tree oil. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were determined. Then, time kill assays, in vitro cytotoxicity and bactericidal activity on latent bacteria (persisters) were investigated. Finally, an in silico study of the pharmacokinetic parameters of α-terpineol was also performed. Altogether, our data demonstrate that the combination of terpinen-4-ol and α-terpineol might be a precious weapon to address ESKAPE pathogens. [ABSTRACT FROM AUTHOR]

Background: Spodoptera littoralis is mostly controlled by the use of synthetic insecticides. Nonetheless, the use of these insecticides causes a slew of issues. On this pest, the antifeedant activity of Melaleuca alternifolia essential oil (EO) and its two principal components was investigated. Results: The gas chromatography–mass spectrometry (GC/MS) analysis revealed that the M. alternifolia EO was composed of eleven compounds. Terpinen-4-ol (40.1%) and γ-terpinene (21.9%) were chosen as the major constituents. In terms of antifeedant efficacy, treatment with M. alternifolia EO and these components reduced leaf consumption and the efficiency of food conversion in larvae in a concentration-dependent manner. When compared to untreated larvae, weight, growth, and pupation percentage were all significantly lower. Conclusions: The findings show that M. alternifolia EO and its components, terpinen-4-ol and γ-terpinene can be effectively combined for cotton leafworm management. Highlights: The chemical composition of M. alternifolia EO was identified by GC–MS. The EO of M. alternifolia and its components, terpinen-4-ol and γ-terpinene, had potent bioactivity against S. littoralis. M. alternifolia EO and their components, terpinen-4-ol and γ-terpinene have great potential as a biopesticide in integrated pest management programs. [ABSTRACT FROM AUTHOR]

Simple Summary: Long noncoding RNAs (lncRNAs) are important regulatory factors in multiple biological processes, including genomic imprinting, cancer, RNA interference, and protein translation. Several lncRNAs can respond to insecticides. However, lncRNA functions associated with terpinen-4-ol resistance in the red flour beetle (Tribolium castaneum) have not yet been identified. In previous work, we found terpinen-4-ol to have strong fumigation activity against store-product pests. As a pesticide from plants, terpinen-4-ol shows nearly no residual danger to the environment; however, resistance is inevitable if people use terpinen-4-ol immoderately. To avoid resistance to terpinen-4-ol occurring in the red flour beetle, we deeply sequenced and tried to find some lncRNAs that can regulate target mRNA expression to reduce terpinen-4-ol. Long noncoding RNAs (lncRNAs) are important regulatory factors in multiple biological processes, and several lncRNAs are known to respond to insecticides. However, the lncRNA functions that are associated with terpinen-4-ol resistance in the red flour beetle (Tribolium castaneum) have not yet been identified. In this study, we determined the differentially transcribed lncRNAs between fumigated and control experimental groups. In the six libraries that underwent RNA sequencing, 34,546 transcripts were identified, including 8267 novel lncRNAs, 4155 novel mRNAs, 1151 known lncRNAs, and 20,973 known mRNAs. Among these, we found that the expression of 1858 mRNAs and 1663 lncRNAs was significantly different in the fumigated group compared with the control group. Among the differentially transcribed lncRNAs, 453 were up-regulated and 1210 were down-regulated lncRNAs. In addition, we identified the regulatory function targets of the lncRNAs. Functionally, all lncRNAs and target genes associated with terpinen-4-ol metabolism were enriched in several metabolic pathways, like the ATP-binding cassette transporter, pentose interconversion, and glucuronate interconversion. To the best of our knowledge, this study represents the first global identification of lncRNAs and their potential association with terpinen-4-ol metabolism in the red flour beetle. These results will provide reference information for studies on the resistance to terpinen-4-ol and other essential oil compounds and chemical pesticides, as well as an understanding of other biological processes in T. castaneum. [ABSTRACT FROM AUTHOR]

To evaluate the improvement of ocular signs and symptoms in patients suffering from Demodex blepharitis using a combined treatment approach: use of eyelid wipes impregnated with 2.5% terpinen-4-ol (T4O) and 0.2% hyaluronic acid (HA) in the initial treatment period and investigation of maintenance of the treatment effect with the use of eyelid cleansing wipes. Fifty patients with Demodex blepharitis were treated in the initial treatment period with sterile eyelid T4O impregnated wipes for 28 days. In the following four-week maintenance period, 82% patients received sterile eyelid maintenance wipes, while 16% continued treatment with T4O impregnated wipes. Global ocular discomfort, adapted TOSS, SANDE score, and individual blepharitis symptoms were assessed by patients at day 28 and day 56. Ocular signs were evaluated by the investigator at the study visits. Investigator's assessment of the overall treatment performance, patient's assessment of treatment satisfaction, and tolerability were evaluated with questionnaires. All global ocular discomfort symptoms and disease specific symptoms assessed by patients as well as all parameters evaluated by the investigators significantly improved in the initial treatment period with the application of eyelid wipes impregnated with 2.5% terpinen-4-ol until day 28. The therapeutic effect was maintained or even improved during the maintenance period under administration of mainly eyelid maintenance wipes until day 56. Both products were well tolerated. No adverse events and no clinically relevant changes in visual acuity were observed during both periods. Once daily treatment with T4O impregnated eyelid wipes in the initial treatment period significantly improved the ocular symptoms and signs and reduced the mite count in patients with Demodex blepharitis within four-weeks administration. Subsequent maintenance treatment with maintenance wipes for another 4 weeks preserved or further intensified the treatment success. The products were well tolerated and were convenient to use. [ABSTRACT FROM AUTHOR]

Background: This study investigated the effects of terpinen-4-ol on methicillin-resistant Staphylococcus aureus (MRSA) and its biofilm, and the possible mechanisms governing this effect. Results: We observed that terpinen-4-ol has good antibacterial activity and inhibits the formation of MRSA biofilm. The MIC and MBC values for terpinen-4-ol against S. aureus were 0.08% ~ 0.32%. And terpinen-4-ol at 0.32% could kill all bacteria and clear all biofilms. Untargeted metabolomic and transcriptomic analyses showed that terpinen-4-ol strongly inhibited DNA and RNA biosynthesis in MRSA at 2 h after treatment by affecting genes and metabolites related to purine and pyrimidine metabolic pathways. Some differential genes which play important roles in DNA synthesis and the production of eDNA from biofilm exposed to terpinen-4-ol was also significantly decreased compared with that of the control. Conclusions: Terpinen-4-ol has good antibacterial activity and significantly inhibits the formation of MRSA biofilm by inhibiting purine and pyrimidine metabolism. [ABSTRACT FROM AUTHOR]

Purpose: To investigate in vitro effects of active ingredients in eye cleansing wipes and solutions on the life span of Demodex.Methods: Demodex mites were extracted by eyelash epilation method from volunteers who were found to have chronic demodex blepharitis during an ophthalmological examination. Preparations with three or more motile, live adult Demodex parasites were included in the study. Two drops of the test solution were dropped on the samples: saline, 2% tea tree oil (TTO; Osto®, AKD Medical products, Turkey), 7.5% TTO (Blefaritto®, Jeomed, Turkey), and 0.5% terpinen-4-ol (T4O; Blefastop plus®, NTC, Italy). Under light microscopy at 100× and 400× magnification, samples were examined and followed. The average killing time of Demodex was noted for each preparation.Results: The study was analyzed on 120 patient samples. In the control group with saline, the average killing time of Demodex had an average of 323.5 ± 21.1 min. In other groups, an average mean of 95.9 ± 25.2 min in the 2% TTO group, 67.1 ± 21.8 min in the 7.5% TTO group, and 27.3 ± 6.0 min in the 0.5% T4O group was observed. It was found that the 0.5% T4O group was significantly more effective than the other groups.Conclusion: Chronic Demodex blepharitis treatment is quite difficult in ophthalmology practice. It appears that, even at very low concentrations, T4O has an effective anti-Demodex effect. [ABSTRACT FROM AUTHOR]

Owing to their extensive biological potential, essential oils (EOs) and their bioactive phytochemicals have gained attention from the scientific community. Within this domain, Terpinen-4-ol (T-4-ol), a bioactive monoterpene alcohol and the major constituent of tea tree oil (TTO), has made its way into translational research. Recent literature on T-4-ol strongly indicates its diverse pharmacological properties, including but not limited to antimicrobial, antivirulent, anti-oxidant, anti-inflammatory, anti-hypertensive, and anti-cancer effects. Hence, this review is the first to provide a comprehensive overview of the sources, bioavailability, safety, pharmaceutical delivery systems, and multifaceted biological properties of T-4-ol, emphasizing its medicinal potential for widescale application. The antibacterial and antifungal effectiveness of T-4-ol has been discussed, encompassing its role in combating a broad spectrum of bacterial and fungal pathogens. The review delves into the antivirulent prospects of T-4-ol, shedding light on its ability to attenuate virulence and mitigate bacterial pathogenesis. Scientific literature on the anti-oxidant and anti-inflammatory activity of T-4-ol highlighting its role in neutralizing reactive oxygen species and modulating inflammatory pathways has also been collated. Furthermore, the review elaborates on the cardioprotective and anti-hypertensive properties of T-4-ol and augments literature on its anti-cancer mechanism against various cancer cell lines. The review also provides in-depth knowledge of the pharmaceutical formulations of T-4-ol and recent knowledge about its application in clinical/field trials. The exploration of these diverse attributes positions T-4-ol as a promising candidate for further research and therapeutic repurposing in various biomedical applications. [Display omitted] • Terpinen-4-ol or 4-carvomenthenol is the principle bioactive component of tea tree oil. • Terpinen-4-ol is a multifaceted phytochemical with diverse pharmacological properties. • It displays broad-range antibacterial, antifungal, and antivirulence properties against multiple pathogens. • The phytochemical exhibits quorum quenching potential against drug-resistant pathogens. • Terpinen-4-ol harbors notable anti-inflammatory, anti-oxidant, anti-hypertensive, and cardioprotective effects. • In vitro and in vivo investigations have highlighted its profound anti-cancer properties. [ABSTRACT FROM AUTHOR]

The present study was focused on exploring the presence of active compounds in Origanum majorana essential oil (OmEO), and its various knock‐down effects against the rice moth, Corcyra cephalonica. GC–MS analysis detected the existence of major compounds such as monoterpenes, cis‐β‐terpineol and terpinen‐4‐ol with the total proportion of 52.16%. Fumigant toxicity against adult and larvae was calculated with an LC50 value of 11.31 and 49.83 μL/L air, respectively. The contact toxicity against adult, pupa, larvae and eggs was observed with LC50 value 2.54, 0.95, 2.78, and 0.49 μL/L, respectively. Furthermore, the influential repellent behavior against adults has been observed. Acetylesterase (AChE) inhibition activity of OmEO was observed against adult and larvae of C. cephalonica with an IC50 value of 35.89 and 118.54 μL/mL, respectively. Moreover, computational docking study revealed the binding affinity of Cis‐β‐terpineol and terpinen‐4‐ol towards the active binding sites of AChE. On the other hand, Fluorescence‐assisted cytometry and comet assay confirmed the cytotoxic and genotoxic effect of OmEO at various concentrations on C. cephalonica. Altogether, the results showed the knock‐down effect of OmEO against C. cephalonica, and it could be a potential biocontrol measure against the stored product pest. [ABSTRACT FROM AUTHOR]

Essential oil from leaf, root, and stem of Peperomia pellucida native to different countries have been isolated and characterized. Variations in the chemical composition of the essential oil from the same part of the plant were established. Meanwhile, the root essential oil of P. pellucida native to Nigeria has not been studied. This work aimed at characterizing the root essential oil of P. pellucida growing in Nigeria. To achieve this, pulverized roots (500 g) of P. pellucida were hydrodistilled and yielded 0.03±0.12 % (w/w) of essential oil. Analysis of the essential oil using GC and GC/MS showed the presence of twenty-three chemical compounds. The essential oil was predominated by sesquiterpenoids, which constituted 87.5 % of the oil. Monoterpenoids constituted 2.9 % of the oil. β-fernesene (22.2 %) was the most predominant compound in the essential oil. Other principal constituents of the oil were; β-bisabolene (14.8 %), β-bergamotene (10.7 %), 1,4- cadinadiene (7.4 %), α-copaene (6.6 %) and isosativene (6.5 %). Terpinen-4-ol (2.3 %) was the major monoterpenoid in the oil, while neryl acetate (0.6 %) existed in appreciable quantity. The predominance of β- fernesene in the oil implied that the oil was of β-farnesene chemotype. [ABSTRACT FROM AUTHOR]

Tea tree oil (TTO) and its two characteristic components (terpinen-4-ol and 1,8-cineole) have been shown to inhibit Botrytis cinerea growth. In this study, we conducted a transcriptome analysis to determine the effects of TTO and its characteristic components, alone and in combination, against B. cinerea. Most differentially expressed genes (DEGs) from B. cinerea cells treated with terpinen-4-ol participated in the biosynthesis of secondary metabolites, and the metabolism of amino acids, carbohydrates, and lipids. All treatments containing terpinen-4-ol potentially induced mitochondrial dysfunction and oxidative stress. These were further confirmed by the decreased activities of several enzymes (e.g., succinate dehydrogenase (SDH), malate dehydrogenase (MDH), α-ketoglutarate dehydrogenase (α-KGDH), isocitrate dehydrogenase (ICDH)), the increased activities of certain enzymes (e.g., catalase (CAT), peroxidase (POD), superoxide dismutase (SOD)), and increased content of hydrogen peroxide (H2O2). 1,8-Cineole mainly affected DEGs involved in genetic information processing, resulting in cell death. This study provides insight into the molecular mechanism of B. cinerea inhibition by TTO, and explains the synergistic effect of terpinen-4-ol and 1,8-cineole on B. cinerea. [ABSTRACT FROM AUTHOR]

Terpinen-4-ol showed highly insecticidal activity to stored-grain pest Sitophilus zeamais , and cytochrome P450s were strongly induced in response to terpinen-4-ol fumigation. Understanding of the function of P450 enzyme system in the susceptibility to terpinen-4-ol in S. zeamais will benefit the potential application of terpinen-4-ol in controlling stored-grain pests. In the present study, the synergist piperonyl butoxide increased the toxicity of terpinen-4-ol to S. zeamais , with a synergism ratio of 3.5-fold. Two isoforms of NADPH-cytochrome P450 reductase (SzCPR) were identified, with the difference at the N-terminal. SzCPR contained an N-terminal membrane anchor, FMN, FAD, and NADP binding domains. Expression levels of SzCPR were upregulated by tea tree oil (TTO) and its main constituent terpinen-4-ol under different concentrations and time periods. RNAi was generated for S. zeamais by feeding adults dsRNA and the knockdown of SzCPR increased the susceptibility of S. zeamais to terpinen-4-ol, with higher mortality of adults than control under terpinen-4-ol fumigation. Further RNAi analysis showed that P450 gene CYP6MS1 mediated the susceptibility of S. zeamais to terpinen-4-ol. These results revealed that cytochrome P450 enzyme system, especially CYP6MS1 participated in the susceptibility of S. zeamais to terpinen-4-ol. The findings provided a foundation to clarify the metabolic mechanisms of terpinen-4-ol in stored-grain pests. Unlabelled Image • PBO increased the toxicity of terpinen-4-ol to S. zeamais , with a synergism ratio of 3.5-fold. • SzCPR was upregulated in response to TTO and its main constituent terpinen-4-ol fumigation. • RNAi through dsRNA feeding was successfully applied in S. zeamais adults. • Knockdown of SzCPR increased the susceptibility of S. zeamais to terpinen-4-ol. • Knockdown of CYP6MS1 increased the susceptibility of S. zeamais to terpinen-4-ol. [ABSTRACT FROM AUTHOR]

Purpose: Demodex folliculorum is a ubiquitous mite that can infest the eyelash follicles. Two commercial lid hygiene products have asserted their effectiveness in killing Demodex mites, yet there has never been a comparative trial between these two products. This study evaluated the demodicidal activity of 0.01% hypochlorous acid (HOCl) solution (Avenova; NovaBay Pharmaceuticals; Emeryville, CA) and 4% terpinen-4-ol (T4O) solution (Cliradex, Bio-Tissue; Miami, FL) in comparison to mineral oil (MO), a negative control. Methods: Live Demodex mites were obtained from volunteers. Samples were immersed in 1–2 drops of test solution: 0.01% HOCl, 4% T4O, or 100% MO. Samples were observed under the microscope every 10 mins for up to 90 mins. Kill time was defined as the elapsed time between the addition of test solution and all cessation of movement of the body, legs, mouth and pedipalps for a minimum of 60 seconds. Results: T4O demonstrated a mean kill time of 40±0.0 mins. HOCl had a mean kill time of 87.86±4.23 mins, with 79% of samples surviving the full 90 mins. In the MO group, all samples survived through the 90 min mark. Kill time was statistically significant in favor of T4O as compared to HOCl (p=0.0005). There was no statistically significant difference in kill time between HOCl and MO (p=0.25). Conclusion: 4% T4O effectively killed all adult mite samples within 40 mins of exposure. In contrast, the demodicidal activity of 0.01% HOCl was minimal, and comparatively similar to 100% MO. [ABSTRACT FROM AUTHOR]

Bark beetles have caused extensive damage to forests in central Sweden during the past decade, and the four‐eyed spruce bark beetle, Polygraphus poligraphus, seems to be involved. However, its role in these bark beetle outbreaks is still not clear. The purpose of this study was to develop an efficient pheromone bait for P. poligraphus, which would make it possible to study the species more carefully and thereby contribute to protect exposed forests in an environmentally friendly way. Three field studies were conducted in 2015, 2016 and 2018 in Medelpad, county of Västernorrland, Sweden. The pheromone of P. poligraphus, (−)‐terpinen‐4‐ol, was tested at different release rates and in different enantiomeric purities, to find the most attractive formulation for the beetles. It was also tested in combination with racemic frontalin, a compound which has previously been shown to produce a synergistic effect together with (−)‐terpinen‐4‐ol of low enantiomeric purity; 52% ee. Other compounds, chosen based on responses from electroantennographic studies, were also tested in an attempt to find additional attractants and repellents for P. poligraphus. The most attractive treatment tested was enantiomerically pure (−)‐terpinen‐4‐ol (99% ee). When the enantiomeric purity was lower (50% ee), the trap catches was lowered to levels comparable to the catches for unbaited control traps. A strong synergistic effect with frontalin was observed for (−)‐terpinen‐4‐ol of low enantiomeric purity (50% ee) but not for the enantiomerically pure compound (99% ee). The release rate of (−)‐terpinen‐4‐ol (99% ee) was shown to be an important factor. For the combination of frontalin and (−)‐terpinen‐4‐ol (50% ee), the attraction seemed strongest when (−)‐terpinen‐4‐ol was released at a higher rate than frontalin. An interesting and novel result was that a repellent compound, α‐terpineol, was identified in our studies. Our results from field studies and electroantennography recordings also indicate that (+)‐terpinen‐4‐ol is a repellent for P. poligraphus. [ABSTRACT FROM AUTHOR]

Purpose: This study investigated the anti-Candida activity and the Shore A hardness of a tissue conditioner (Softone™) modified by incorporation of terpinen-4-ol and cinnamaldehyde. Material and methods: Agar diffusion, microdilution, and mechanism of action methods were performed to determine to evaluate the antifungal activity of phytoconstituents. Then, phytoconstituents in varying concentrations were incorporated into the tissue conditioner. The anti-Candida effect of the modified conditioner was evaluated through agar punch well and biofilm formation methods. Shore A hardness of the experimental liners was evaluated after baseline, 24 h, 48 h, 4 days, and 7 days immersion on artificial saliva. Results: The phytoconstituents incorporated into Softone showed completely inhibited fungal growth in concentrations of 20–40% and did not present significant antifungal activity until their concentrations where higher than 5%. There were differences between non-modified Softone and M5, M10, C10, and T10% (p < 0.05). The groups containing 10–40% of cinnamaldehyde incorporated into Softone were able to completely inhibit the biofilm. Concentrations below 40% of terpinen-4-ol showed unsatisfactory biofilm inhibition. The T40% and C40% groups presented the lowest Shore A hardness values. Hardness values from groups T40% at 7 days (p = 0.476); C40% at 4 days (p = 0.058); and T20% (p = 0.058), C20% (p = 0.205), T30% (p = 0.154), and C30% (p = 0.874) after 48 h did not differ from the control group. Conclusions: Cinnamaldehyde incorporated into Softone inhibited Candida biofilm formation at concentrations of 10–40%, being more effective than terpinen-4-ol modification despite of halo inhibition observed by both products. Clinical relevance: All modifications showed a very similar pattern of hardness being useful for clinical practice. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the clinical improvement in ocular symptoms and signs in patients suffering from Demodex anterior blepharitis after using a novel cleansing wipe impregnated with 2.5% terpinen-4-ol and 0.2% hyaluronic acid. Study design: This was an exploratory, multicenter, open, randomized, two-parallel group comparative study. Methods: Forty-eight patients with Demodex anterior blepharitis were randomly assigned to apply the sterile wipe T1172 (Blephademodex®), either once daily (n=24, Group 1) or twice daily (n=24, Group 2) for 29 days. Overall ocular discomfort and other individual symptoms were measured using a 0–10 numeric rating scale at Day 8 and Day 29. Ocular signs, including eyelid margin hyperemia and number of cylindrical dandruff, were examined at slit lamp. Overall treatment performance by investigator, patient satisfaction and tolerance were evaluated with questionnaires. Results: Overall ocular discomfort was significantly reduced from baseline (p<0.0001) in both groups at Day 8 (−3.6±0.3 in Group 1 and −4.0±0.4 in Group 2) and Day 29 (−5.7±0.4 and −6.8±0.7, respectively), with no difference between groups (D8: p=0.718; D29: p=0.505). Each ocular symptom associated with Demodex blepharitis was improved in both groups. Eyelid margin hyperemia was significantly reduced at Day 8 (−0.7±0.7; p<0.001) and Day 29 (−1.1±0.7; p<0.0001) in Group 1. Similar results were observed in Group 2 (Day 8: p<0.001; Day 29: p<0.0001). Total disappearance of cylindrical dandruff was reported in 30.4% of patients in Group 1 and 43.5% in Group 2. Improvements in other ocular signs were observed in both groups. The product was well tolerated. All patients were satisfied or very satisfied and would continue using it. Conclusion: Daily eyelid hygiene using this cleansing wipe impregnated with 2.5% terpinen-4-ol and 0.2% hyaluronic acid during a 4-week period led to a rapid and marked reduction in ocular symptoms and signs associated with Demodex anterior blepharitis and was well tolerated. [ABSTRACT FROM AUTHOR]

Terpinen-4-ol has potent antifungal activity and controls decay in postharvest strawberry fruit. In order to overcome the unstable and volatile characteristics of terpinen-4-ol, a γ-cyclodextrin (γ-CD) metal-organic framework (MOF) with high porosity and large specific surface area was synthesized by vapor diffusion and ultrasonic mixing. Terpinen-4-ol-loaded γ-CD-MOF (γ-CD-MOF/Ter) was then prepared using physical adsorption. Scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy analysis, and nitrogen adsorption-desorption showed that terpinen-4-ol was successfully loaded into the center of the γ-CD-MOF structure, and that encapsulation efficiency and drug loading reached 53.61% and 9.31%, respectively. γ-CD-MOF/Ter reduced the release rate of terpinene-4-ol, and exhibited the higher antifungal effect against B. cinerea in vitro test. Meanwhile, it was effective in controlling gray mold and maintaining the quality of strawberry fruit. We conclude that γ-CD-MOF loads terpinen-4-ol and reduces its volatilization and has potential application in the preservation of strawberry fruit. • γ-CD-MOF was prepared using vapor diffusion combined with ultrasonic mixing. • Terpinen-4-ol was loaded into γ-CD-MOF with high encapsulation efficiency. • γ-CD-MOF/Ter has good thermal stability and sustainably releases terpinen-4-ol. • γ-CD-MOF/Ter has in vitro and in vivo anti-fungal properties. [ABSTRACT FROM AUTHOR]

Abstract Terpenes – the essential oil components - due to confirmed antimicrobial effect can be applied e.g. as ecological pesticides instead of synthetic and environmentally hazardous compounds. A practical use of these systems must be proceeded by the analysis of the properties and activity of a given mixture. In this paper the monolayers at the air/water solution interface were applied to verify the influence of eucalyptol/terpinen-4-ol mixtures on plant pathogen Botrytis cinerea model membrane. The experiments included the measurements of the surface pressure – area isotherms for model membranes on water and terpene solutions as well as terpenes penetration into lipid monolayers. In the studies done for particular terpenes stronger ability of terpinen-4-ol over eucalyptol to incorporate into membrane, alter the membrane lateral elasticity and decrease its stability was found. Based on the results for the mixtures composed of terpenes in various concentrations it was found that not only the concentration of the system but also its composition, namely the proportion of both terpenes, determines the influence on lipid system. Moreover, terpinen-4-ol, but not eucalyptol, even in low concentrations, was of strong influence on membrane activity of total mixture. Additionally, it was suggested that terpinen-4-ol acts as penetration enhancer for eucalyptol into the model membrane system. Highlights • Eucalyptol and terpinen-4-ol change elasticity of model Botrytis cinerea membrane. • Both concentration and composition of terpene mixture define its properties. • Terpnene-4-ol enhances penetration of eucalyptol into model plant pathogen membrane. [ABSTRACT FROM AUTHOR]

Terpinen-4-ol, the major constituent of tea tree oil, has been reported to have anti-inflammatory effect. However, whether terpinen-4-ol could attenuate LPS-induced inflammation in lung tissues remains unclear. In the present study, we aimed to investigate the protective effects of terpinen-4-ol on LPS-induced acute lung injury (ALI) in mice. Terpinen-4-ol could inhibit LPS-induced ALI as confirmed by the decreased lung histopathological changes, MPO activity, and lung W/D ratio caused by terpinen-4-ol. The production of TNF-α and IL-1β in the BALF was suppressed by the treatment of terpinen-4-ol. Western blot analysis showed that terpinen-4-ol significantly attenuated LPS-induced phosphorylation of IκBα and NF-κB p65. Furthermore, the expression of PPAR-γ was dose-dependently upregulated by the treatment of terpinen-4-ol. In conclusion, the results of this study indicated that terpinen-4-ol inhibited LPS-induced ALI via activating PPAR-γ, which subsequently attenuated LPS-induced NF-κB activation and inflammatory response. [ABSTRACT FROM AUTHOR]

Australian tea tree oil (TTO) and its extract terpinen-4-ol (T4O) are found to be effective in moderating demodex-related diseases. Their possible effects are lowering the mite counts, relieving the demodex-related symptoms and modulating the immune system especially the inflammatory response. This review summarizes the topical treatments of TTO and T4O in human demodicosis, their possible mechanism of actions, side-effects and potential resistance in treating this condition. Although current treatments other than TTO and T4O are relatively effective in controlling the demodex mite population and the related symptoms, more research on the efficacy and drug delivery technology is needed in order to assess its potential as an alternative treatment with minimal side-effect profile, low toxicity and low risk of demodex resistance. [ABSTRACT FROM AUTHOR]

Plant essential oils with high bioactivity provide environmental friendly alternatives for synthetic pesticides. Melaleuca alternifolia essential oil and its main constituent terpinen-4-ol have high insecticidal activity to Sitophilus zeamais Motschulsky. Terpinen-4-ol may be metabolized by human and insect cytochrome P450s. However, little is known about how insects systemically respond to terpinen-4-ol. In this study, we used an RNA-seq approach to evaluate the global gene expression of S. zeamais after terpinen-4-ol fumigation. Duplicates of fumigated and control groups, for a total of four libraries, were collected for sequencing. A total of 36,117 unigenes with an average length of 1036 bp were generated in the de novo assembled transcriptome. Comparative analysis of S. zeamais libraries identified 592 differentially expressed genes (DEGs), of which 308 and 284 genes were up- and down-regulated in response to terpinen-4-ol fumigation, respectively. GO and KEGG functional analyses were performed for up and downregulated DEGs separately, showing these DEGs were enriched for terms related to catalytic activity, carbohydrate metabolism, and xenobiotics biodegradation and metabolism. DEGs encoding enzymes for detoxification were detected, including sixteen cytochrome P450s (P450s), eight glutathione S -transferase (GSTs), fourteen esterase (ESTs), ten UDP-glucuronosyltransferase (UGTs), and two ATP-binding cassette transporter (ABC transporter) genes. Real-time quantitative PCR confirmed that ten P450s, three GSTs and one EST were up-regulated dramatically after exposure to terpinen-4-ol at different concentrations and over a time course. The results provided a transcriptional overview of the changes in a stored-grain pest in response to terpinen-4-ol fumigation. The analysis revealed the expression levels of detoxification genes were altered, especially for P450s, and provided candidate genes for understanding systemic metabolic responses to terpinen-4-ol in insects. [ABSTRACT FROM AUTHOR]

Alpinia zerumbet is a plant from the Zingiberaceae family, popularly used for hypertension treatment. Several studies have demonstrated Alpinia zerumbet vasodilator effect on conductance vessels but not on resistance vessels. Thereby, the aim of this study was to verify the vasodilator effect of the essential oil of Alpinia zerumbet (EOAz) on isolated rat resistance arteries and characterize its mechanism of action. Therefore, the effect of EOAz (3 to 3000 μg/mL) was verified in second-order branches of the mesenteric artery (SOBMA) pre-contracted by KCl and U46619. To study the mechanism of action, the influence of several inhibitors (TEA, 4-AP, Glibenclamide, Atropine, L-NAME, ODQ and indomethacin) on the vasodilator effect of EOAz was evaluated. Some protocols were also performed aiming to study the effect of EOAz on Ca2+ influx and release from intracellular storage. Furthermore, the binding energy of the main constituents with calcium channels were evaluated by molecular docking. Results showed an endothelium-independent vasorelaxant effect of EOAz on SOBMA, and only ODQ and L-NAME produced significant alteration on its pEC 50. Regarding the calcium assays, contraction reduction caused by incubation with EOAz was observed in all three protocols. Hence, our results suggest that EOAz has a vasodilator effect mediated by inhibition of Ca2+ influx and release from intracellular storage, as well as an activation of the NOS/sGC pathway. [Display omitted] • Essential oil of Alpinia zerumbet has a vasodilator effect on the second-order branch of the mesenteric artery. • Its mechanism probably involves blocking of calcium mobilization. • Terpinen-4-ol showed good binding energy with the three calcium channels assessed by docking (VGCC, RyR and IP3R). • Terpinen-4-ol exhibited the same binding site of caffein in the ryanodine receptor with excellent binding energy. [ABSTRACT FROM AUTHOR]

Melaleuca (Melaleuca alternifolia) essential oil (MEO), commonly known as tea tree oil, is popularly used in skincare products. In the current study, we investigated the biological activity of a commercially available MEO (with terpinen-4-ol as the major active component) in pre-inflamed human dermal fibroblasts, which were designed to simulate chronic inflammation. We analyzed the levels of seventeen biomarkers that are important in inflammation and tissue remodeling. Additionally, we studied the effect of MEO on genome-wide gene expression. MEO showed a robust antiproliferative activity against the cells. It also increased the levels of monocyte chemoattractant protein 1, an inflammatory chemokine and several tissue remodeling molecules such as epidermal growth factor receptor, matrix metalloproteinase 1 and tissue inhibitor of metalloproteinase-1 and -2. It was also noted that MEO diversely modulated global gene expression. Furthermore, Ingenuity Pathway Analysis showed that MEO affects many important signaling pathways that are closely related to metabolism, which suggests its potential modulation of metabolism. The results provide an important evidence of the biological activity of MEO in human dermal fibroblasts. They also suggest that MEO plays useful roles in tissue remodeling and metabolism; however, further research is needed to explore the mechanisms underlying these actions. [ABSTRACT FROM AUTHOR]

Oxidative stress has been linked to a pathological mechanism that contributes to the initiation and progression of hepatic injury during Ichthyophthirius multifiliis infection. Thus, natural compounds with antioxidant and free radical scavenger properties, such as the Melaleuca alternifolia essential oil (TTO), might help to prevent or reduce hepatic damage. Thus, the aim of this study was to investigate whether TTO is capable of preventing or reducing hepatic oxidative damage in silver catfish naturally infected with I. multifiliis. After a TTO bath treatment of 1 h/day for 4 days, the number of trophonts on the skin of catfish was reduced by 94.87% compared to the control group. Hepatic samples from fish infected by I. multifiliis showed increased thiobarbituric acid reactive substances (TBARS) and protein carbonylation levels, while catalase (CAT) activity decreased compared to uninfected and untreated animals. Moreover, the histopathology analyses demonstrated the presence of necrosis, nuclear lateralization and cariorrexis, as well as swelling and vacuolization of cytoplasm. Treatment with TTO reduced hepatic TBARS and protein carbonylation levels and ameliorated the antioxidant system of infected fish, as well as preserve the hepatocytes morphology, but not prevented the occurrence of necrosis. Based on our findings, we propose that TTO is an alternative therapeutic option for silver catfish infected with I. multifiliis . Moreover, TTO treatment is a useful approach for avoiding or minimizing the hepatic oxidative stress caused by I. multifiliis, thus improving the hepatic antioxidant system. [ABSTRACT FROM AUTHOR]

In the present study, 42 pure monoterpenes and volatile aromatic compounds were tested to evaluate their toxicities against adults of granary weevil, Sitophilus granarius (L.) (Coleoptera: Curculionidae) at laboratory condition. For the insecticidal activity tests, 10 and 20 µL/Petri dish concentrations for liquid compounds and 10 and 20 µg/Petri dish concentrations for solid compounds were used. The results show that majority of tested compounds were found to be toxic against to the adults of S. granarius and they showed various degrees of toxicity with range of 6-100% mortality. Among the compounds tested, oxygenated monoterpenes, linalool, carvacrol, terpinen-4-ol, limonene oxide, carvone, dihydrocarvone, fenchone, menthone and aromatic volatiles, p-anis aldehyde, benzyl acetate, cinnamyl aldehyde in the current study displayed complete mortality on the pest adults after 24h of exposure. In general, oxygenated monoterpenes and aromatic compounds exhibited high toxicity as compared with monoterpene hydrocarbons. Among the monoterpenes hydrocarbons, the highest toxic effects were shown by γ-terpinene, limonene and β-pinene. Our results showed that linalool, carvacrol, terpinen-4-ol, limonene oxide, carvone, dihydrocarvone, fenchone, menthone, p-anisaldehyde, benzyl acetate and cinnamyl aldehyde were the most toxic compounds against the adults of the pest. Therefore, these compounds can be used as natural insecticides against the S. garanarius adults. [ABSTRACT FROM AUTHOR]

Terpinen-4-ol (TP4O) is the main component of the essential oil extracted from Melaleuca alternifolia, known as the tea tree, of the botanical family Myrtaceae. The anticancer effects of TP4O have been reported in several cancer cell lines. Previous reports have demonstrated that TP4O exerts anticancer effects by inducing apoptotic cell death in several cell lines; however, the underlying molecular mechanisms of these effects remain unclear. In the present study, the anticancer effects of TP4O against the colorectal cancer (CRC) cell lines HCT116 and RKO were evaluated using WST-8 and bromodeoxyuridine assays. The mechanism of cell death was investigated by the measurement of caspase-3/7, Annexin V and lactate dehydrogenase release. Reactive oxygen species (ROS) levels induced by TP4O were evaluated by electron spin resonance and quantitative measurement of dihydroethidium. Localization of the ROS derived from mitochondria was observed by confocal inverted microscopy. Protein levels of ROS scavengers were assessed by western blotting analysis. To confirm the role of ROS, cell viability was measured in the presence of antioxidant reagents. In an in vivo xenograft model of ICR-SCID mice implanted with HCT116 cells, 200 mg/kg TP4O was injected locally, and tumor growth was compared with that of the control. TP4O induced apoptotic cell death in HCT116 and RKO cells in a dose-dependent manner, and TP4O also increased the levels of ROS generated by mitochondria. TP4O-induced cell death was rescued by administration of antioxidant regents. In vivo, TP4O inhibited the proliferation of HCT116 xenografts compared with that of the control group. The results of the present study suggest that TP4O induces apoptosis in CRC cells through ROS generation. Furthermore, TP4O is potentially useful for the development of novel therapies against CRC. [ABSTRACT FROM AUTHOR]

The use of essential oils (EOs) in the perfumery, agriculture, food industry and cosmetics is quite common owing to their aromatic properties. Tea tree oil is an EO with immense potential for the treatment of dermatological disorders due to its antimicrobial properties against broad spectrum of micro-organisms. It has minimal tendency to develop resistance. It is obtained from the leaves ofMelaleuca alternifolia, an Australian species, by steam distillation. It is a mixture of components like monoterpenes, sesquiterpenes and their alcohols, contributing to various (analgesic, antiviral, antibacterial, antifungal, antiprotozoal, anti-inflammatory, antioxidant and anticancer) activities. Tea tree oil is reported to overcome resistance development by bacterial species towards conventional drugs. However, its hydrophobic nature, volatility and sensitivity to light, air and temperature, pose challenges to formulation scientists for its effective delivery. Tea Tree oil is reported as a safe, natural and effective agent. Since, specific knowledge on the chemical composition and properties of oil is fundamental for its adequate use, the present review compiles and discusses the hitherto scattered data on activities, tolerability, safety, toxicity and stability concern of tea tree oil. It also sheds light on various reported drug delivery systems and applications of this EO.ABSTRACT FROM PUBLISHERCopyright of Journal of Essential Oil Research is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. [ABSTRACT FROM AUTHOR]

As Kupffer cells are highly involved in the regulation of hepatic inflammatory response, the main goal of this study was to improve and to characterize a hepatocyte-Kupffer cell co-culture of pig origin for modelling endotoxin-induced hepatic inflammation and for testing the efficacy of potential anti-inflammatory substances. This monolayer co-culture was prepared from primary isolated swine hepatocytes and Kupffer cells in the ratio of 6:1 and 2:1, mimicking different states of liver inflammation. The prepared cell cultures were characterized by immunohistochemical CD-68 detection. Lipopolysaccharide ( LPS) challenge of both co-cultures resulted in elevated interleukin-8 ( IL-8) and that of 6:1 co-cultures in increased IL-6 production with a higher extent than on hepatocyte monocultures, justifying the key role of Kupffer cells in pro-inflammatory cytokine production. LPS-induced IL-8 production was successfully attenuated by concomitant application of both sodium butyrate and terpinen-4-ol on hepatocyte monocultures, but not on co-cultures, demonstrating the importance of the presence of Kupffer cells in cell cultures as inflammatory models. Based on these initial data, the applied porcine primary hepatocyte-Kupffer cell co-culture is suggested to be a proper tool for in vitro investigations on liver physiology and hepatic inflammation in pigs and can be used as a useful model mimicking in vivo conditions in veterinary research. [ABSTRACT FROM AUTHOR]

To assess the changes in essential oil content and composition of sweet- marjoram (Origanum majoranaL.) during post harvest drying / storage, an experiment was conducted in the hilly region of Uttarakhand. Drying of sweet-marjoram herb under shade and field conditions prior to distillation increased the essential oil recovery by 11.1 %. Altogether, twenty-seven constituents, representing 93.23-98.81 % of the total oil compositions were identified using GC/FID and GC/MS techniques. Major constituents of the oil werecis-sabinene hydrate (20.23-46.27 %), terpinen-4-ol (9.32-23.43 %), γ-terpinene (5.67-13.76 %), α-terpinene (2.98-8.38 %), sabinene (4.90-8.17 %),trans-sabinene hydrate (5.01-7.34 %) and α-terpineol (3.41-4.17 %). The amount ofcis-sabinene hydrate decreased on shade drying and subsequent storage under shade conditions (from 37.05 to 20.23 %); however, its content was improved on drying under space conditions (37.52-46.27 %) as compared to the fresh herb (37.05 %). [ABSTRACT FROM AUTHOR]

• The industrially – relevant product terpinen–4–ol is produced without isomers. • The synthesis proceeds with simple solid catalysts in 66% yield. • Batch and in – flow processes are both studied at multigram scale. • The synthetic three – step sequence is 100% atom economic. • Nanotitania is a competent catalyst for the isomerization of epoxides to allyl alcohols. Terpinen–4–ol is a natural product with wide application in the fragrance and agrochemical industry, currently extracted from tea tree oil or synthesized from either base–promoted rearrangement of 1,4–cineol or acid–catalyzed hydration of limonene. However, these synthetic processes, based on aggressive, unrecoverable homogeneous reagents, are non–selective and give significant amounts of isomers, which severely complicate and make more expensive the purification of the active substance. Here we show the isomers–free synthesis of terpinen–4–ol, exclusively over solid catalysts such as alumina, nanotitania and Pd/C, in >60% yield, by selective epoxidation, isomerization of terpinolene epoxide and allyl alcohol hydrogenation. The synthesis can be performed either in batch or in flow mode for the isomerization of terpinolene epoxide. The use of bare nanotitania as a selective epoxide isomerization catalyst, here demonstrated, opens new ways for the synthesis of quaternary alcohols. [Display omitted] [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the short-term tolerability of five commercially available anti-demodectic eyelid cleansers; OCuSOFT Oust Demodex (OD), I-MED I-Lid'n Lash Plus (ILL+), Labtician BlephaDex (BD), Chrissanthe Eye Cleanse (EC), and Théa Blephademodex (BDdx).Methods: Thirty healthy non-contact lens wearers (18 female; mean ± SD age, 33 ± 12 years) were enrolled in a prospective randomised crossover study. On separate visits, spaced at least 48 h apart, participants were randomised to receive topical application of one of five eyelid cleansers or saline. Participants rated subjective ocular discomfort during the 10-minute post-application period. Visual acuity, non-invasive tear film stability, conjunctival hyperaemia, and ocular surface staining were assessed at baseline and 10 min.Results: No inter-group differences in ocular parameters were noted at baseline (all p > 0.05). Ocular discomfort scores significantly exceeded baseline scores for 60 s following BD application, 120 s with OD, 135 s with BDdx, 150 s with ILL+, and 195 s with EC (all p < 0.05). Deterioration in non-invasive tear film stability, limbal conjunctival hyperaemia, as well as corneal, conjunctival, and lid margin staining was detected following EC application (all p < 0.05), and increased bulbar conjunctival hyperaemia was observed following both EC and ILL+ treatment (both p < 0.05).Conclusions: Study outcomes highlight varying tolerability profiles with different anti-demodectic lid cleanser preparations, and the potential to induce tear film instability, conjunctival hyperaemia and ocular surface staining on application. Awareness of possible adverse effects arising from topical application of commercial anti-demodectic lid cleanser formulations may help clinicians set realistic patient expectations and encourage better compliance in their use of lid hygiene therapies. [ABSTRACT FROM AUTHOR]

The essential oils obtained by steam distillation of aerial parts ofSantolina africanaJord. & Fourr. an endemic species to North Africa andSantolina chamaecyparissusL. growing in the East of Algeria were analyzed by GC and GC-MS. The main components ofS. africanawere β-pinene (12.78 %), 1,8-cineol (10.02 %), myrcene (6.94 %), curcumene (7.96 %), spathulenol (5.96 %) and β-eudesmol (14.58 %). These results were slightly different from a previous study which reported from the same species: terpinen-4-ol (44 %), borneol (6.73 %), camphor (15.11 %) and α-terpineol (11.31 %). Our results concerningS. chamaecyparissusshowed as main components: thujene (2.46 %), camphene (6.84 %), myrcene (6.44 %), 1,8-cineol (11.22 %), terpinen-4-ol ( 4.93 %), spathulenol (7.59 %) and β-eudesmol (3.76 %). [ABSTRACT FROM AUTHOR]

Aims The essential oil of Melaleuca alternifolia (tea tree) has been evaluated as a potential eco-friendly antifungal agent against Botrytis cinerea. In this study, we investigated the antifungal activity and mode of action of tea tree oil (TTO) and its components against B. cinerea. Methods and Results Of the components we tested in contact phase, terpinen-4-ol had the highest antifungal activity, followed by TTO, α-terpineol, terpinolene, then 1,8-cineole. As one of characteristic components of TTO, terpinen-4-ol treatment led to pronounced alterations in mycelial morphology, cellular ultrastructure, membrane permeability under scanning electron microscope, transmission electron microscope and fluorescent microscope, and also reduced the ergosterol content of fungi. As another characteristic component, 1,8-cineole caused serious intracellular damage but only slightly affected B. cinerea otherwise. When terpinen-4-ol and 1,8-cineole were used together, the synergistic antifungal activity was significantly higher than either component by itself. Conclusions The results of our study confirmed that terpinen-4-ol and 1,8-cineole act mainly on the cell membranes and organelles of B. cinerea, respectively, and when combined are similar to TTO in antifungal activity due to their differences. Significance and Impact of the Study Understanding the mechanism of terpinen-4-ol and 1,8-cineole antifungal action to B. cinerea is helpful for investigation on their synergistic effect and explaining antifungal action modes of TTO. [ABSTRACT FROM AUTHOR]

Terpinen-4-ol, the main component of Australian tea tree oil, which was widely used in pharmaceutical and cosmetic fields, was chosen as the active component in this study because of its excellent antimicrobial properties and good permeability. The objective of this study was to investigate the relationships between rheological characters, in vitro release and permeation profiles of the emulgels. Particle size distribution, optical microscopy tests were performed to characterize the status of the emulgels. Scanning electron microscopy and rheology tests were carried out to assess the strength of the structures. In vitro release and percutaneous permeation study of Terpinen-4-ol through Cellophane® membrane and excised rabbit skin were conducted by vertical Franz diffusion cell, respectively. All of the emulgel samples showed a non-uniform bimodal distribution and the microstructure represented a matrix type which could inhibit the diffusion of oil droplets in formulation in some extent. Rheological data showed a good fit to the Herschel–Bulkley model in viscosimetric studies regardless of the polymers used. Moreover, 10% Sepiplus 400 had obtained the highest zero-shear viscosity, G′, G″ value and lowest τ 95%G ′ value corresponding to the strongest structure. The results of in vitro release tests revealed that an increase in viscosity may affect the release profiles inversely, irrespective of the polymers used. In vitro permeation of Terpinen-4-ol tests indicated that when the drug amount released could satisfy the essential driving force, permeation processes was independent of release. In contrast, the drug amount released could not satisfy the essential driving force, the permeation amount was inversely proportional to the viscosity as the release amount did. [ABSTRACT FROM AUTHOR]

The chemical composition of the essential oil from the leaves ofPseudobrickellia brasiliensis(Asteraceae) from the Brazilian Cerrado was analyzed by GC/FID and GC/MS. Thirty-four out of thirty-eight components detected were identified. Major compounds in the oil were terpinen-4-ol (38.6%), γ-terpinene (19.5%), α-terpinene (7.8%) and α-terpineol (4.5%). [ABSTRACT FROM PUBLISHER]

The deterpenation process of essential oils consists of terpene removal and a consequent concentration of oxygenated compounds, which increases the sensorial quality, the aromatic potential and the oxidative stability of the oil. Deterpenation of oregano ( Origanum vulgare L ., Lamiaceae) essential oil, which has been used extensively as a popular medication and as an antimicrobial, antifungal, antimutagenic and a powerful antioxidant agent, can be performed by (liquid + liquid) extraction using hydroalcoholic solvents. This research presents (liquid + liquid) equilibrium data for model systems composed of p -cymene, thymol, terpinen-4-ol and α-terpineol, some of the main components of oregano essential oil, using hydrous ethanol as the solvent with the water mass fraction ranging from 0.28 to 0.41 at T = (298.2 ± 0.1) K. The results show that an increase in the hydration of the alcoholic solvent causes a negative influence on the values of the distribution coefficient for the three oxygenated compounds (thymol, terpinen-4-ol and α-terpineol), with an increase in solvent selectivity. An increase in the content of oxygenated compounds in the terpene-rich phase reduces their distribution coefficients and the selectivity values. In addition, binary interaction parameters were estimated correlating the experimental data using the NRTL and UNIQUAC thermodynamic models, and the global deviations were lower than 0.0060 for all systems, indicating that both molecular models show a good descriptive performance. [ABSTRACT FROM AUTHOR]

This work demonstrates the potential of fast multiple heart-cut enantioselective multidimensional gas chromatography (GC − e GC) and enantioselective comprehensive two-dimensional gas chromatography ( e GC × GC), to perform the stereoisomeric analysis of three key chiral monoterpenes (limonene, terpinen-4-ol and α-terpineol) present in tea tree oil (TTO). In GC − e GC, separation was conducted using a combination of mid-polar first dimension ( 1 D) column and a chiral second dimension ( 2 D) column, providing interference-free enantioresolution of the individual antipodes of each optically active component. A combination of 1 D chiral column and 2 D polar columns (ionic liquid and wax phases) were tested for the e GC × GC study. Quantification was proposed based on summation of two major modulated peaks for each antipode, displaying comparable results with those derived from GC − e GC. Fast chiral separations were achieved within 25 min for GC − e GC and < 20 min for e GC × GC, while ensuring adequate interference-free enantiomer separation. The suitability of using these two enantioselective multidimensional approaches for the routine assessment of chiral monoterpenes in TTO was evaluated and discussed. Exact enantiomeric composition of chiral markers for authentic TTOs was proposed by analysing a representative number of pure TTOs sourced directly from plantations of known provenance in Australia. Consistent enantiomeric fractions of 61.6 ± 1.5% (+):38.4 ± 1.5% (−) for limonene, 61.7 ± 1.6% (+):38.3 ± 1.6% (−) for terpinen-4-ol and 79.6 ± 1.4% (+):20.4 ± 1.4% (−) for α-terpineol were obtained for the 57 authentic Australian TTOs. The results were compared (using principle component analysis) with commercial TTOs (declared as derived from Melaleuca alternifolia ) obtained from different continents. Assessing these data to determine adulteration, or additives that affect the enantiomeric ratios, in commercially sourced TTOs is discussed. The proposed method offers distinct advantages over e GC, especially in terms of analysis times and selectivity which can serve as a reliable platform for authenticity control of TTO. [ABSTRACT FROM AUTHOR]

This work demonstrates the potential of fast multiple heart-cut enantioselective multidimensional gas chromatography (GC − e GC) and enantioselective comprehensive two-dimensional gas chromatography ( e GC × GC), to perform the stereoisomeric analysis of three key chiral monoterpenes (limonene, terpinen-4-ol and α-terpineol) present in tea tree oil (TTO). In GC − e GC, separation was conducted using a combination of mid-polar first dimension ( 1 D) column and a chiral second dimension ( 2 D) column, providing interference-free enantioresolution of the individual antipodes of each optically active component. A combination of 1 D chiral column and 2 D polar columns (ionic liquid and wax phases) were tested for the e GC × GC study. Quantification was proposed based on summation of two major modulated peaks for each antipode, displaying comparable results with those derived from GC − e GC. Fast chiral separations were achieved within 25 min for GC − e GC and < 20 min for e GC × GC, while ensuring adequate interference-free enantiomer separation. The suitability of using these two enantioselective multidimensional approaches for the routine assessment of chiral monoterpenes in TTO was evaluated and discussed. Exact enantiomeric composition of chiral markers for authentic TTOs was proposed by analysing a representative number of pure TTOs sourced directly from plantations of known provenance in Australia. Consistent enantiomeric fractions of 61.6 ± 1.5% (+):38.4 ± 1.5% (−) for limonene, 61.7 ± 1.6% (+):38.3 ± 1.6% (−) for terpinen-4-ol and 79.6 ± 1.4% (+):20.4 ± 1.4% (−) for α-terpineol were obtained for the 57 authentic Australian TTOs. The results were compared (using principle component analysis) with commercial TTOs (declared as derived from Melaleuca alternifolia ) obtained from different continents. Assessing these data to determine adulteration, or additives that affect the enantiomeric ratios, in commercially sourced TTOs is discussed. The proposed method offers distinct advantages over e GC, especially in terms of analysis times and selectivity which can serve as a reliable platform for authenticity control of TTO. [ABSTRACT FROM AUTHOR]

The growing awareness of a mounting trend toward adulteration of essential oil products has resulted in considerable interest among producer and consumer industries to develop suitable and cost-effective methods for authenticity control. In response to this trend, this study reports authenticity assessment of Australian tea tree oil (TTO) by means of stereospecific analysis of designated chiral monoterpenes present within the oil. Enantioselective gas chromatography ( e GC) coupled with either flame ionization detection or mass spectrometry was used to determine the enantiomeric distribution of terpinen-4-ol and α-terpineol, both key chemical markers in TTO. Consistent enantiomeric ratios of 68.5 ± 0.2% (+): 31.5 ± 0.2% (–) for terpinen-4-ol and 74.2 ± 1.4% (+): 25.8 ± 1.4% (–) for α-terpineol were observed for the 57 authentic 100% pure Australian TTOs analyzed, which were sourced directly from different plantation sites throughout Australia. On the other hand, considerable variations from these ratios were observed for a number of commercial TTOs sampled from different continents, with 50% of the samples varying markedly from the ∼68.5% value found for (+) terpinen-4-ol. Robustness of the method and reliability of the attained results were evaluated by cross-checking data derived from the two independent analyses performed in this study. To the best of our knowledge, this work encapsulates the most comprehensive dataset currently available for the enantiomeric distribution of terpinen-4-ol and α-terpineol in pure Australian TTO, and which can serve as an important reference for detection of variation in commercially-sourced samples, and be a potential indicator of adulteration. Additionally, results of this study proved the considerable potential of using chiral compositions of terpinen-4-ol and α-terpineol as chiral signatures for authenticity assessment of TTO. [ABSTRACT FROM AUTHOR]