Eucalyptus citriodora (lemon eucalyptus) is a medicinal plant commonly used as an antiseptic agent to prevent infection and promote healing. The aim of this exploration was to investigate for the first time the antibacterial mode of action of a gas chromatography-mass spectrometry chemically characterized E. citriodora essential oil (EO) obtained by microwave-assisted hydrodistillation. First, the chemical investigation revealed citronellal (30.67%) and citronellol (19.14%) as the major components. E. citriodora EO represented remarkable antibacterial properties, as demonstrated by significant zone of inhibition in the disc-diffusion test against all tested bacterial pathogens, including Listeria innocua ATCC 33090, L. monocytogenes ATCC 13932, Proteus mirabilis ATCC 25933, Salmonella typhimurium ATCC 700408, and Pseudomonas aeruginosa ATCC 27853. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values confirmed these findings showing antibacterial efficacy at low concentrations ranging 5.75-92 µg/mL for MICs and 11.5-184 µg/mL for MBCs. These results were comparable with gentamicin. The MICindex revealed that E. citriodora EO has bactericidal effects. We evaluated the antibacterial properties of E. citriodora EO and determined its mode of action using advanced tests with P. aeruginosa as a typical pathogen. The time-kill test revealed dose-dependent inhibitory effects on the cell proliferation of P. aeruginosa, affecting its membrane permeability based on the time and concentration of the EO. E. citriodora EO also caused damage to the cell membrane, resulting in leakage of cellular constituents, including RNA and DNA. Anti-quorum sensing activity was tested by inhibiting biofilm formation, showing that E. citriodora EO effectively inhibited biofilm formation. The UV-visible investigation on the release of cellular materials absorbed at 260 nm showed significant leakage of cytoplasmic substances, including proteins, DNA, and RNA, indicating devastation to bacterial cell membrane integrity. In addition, the use of E. citriodora EO significantly inhibited P. aeruginosa adhesion on 304 L stainless-steel surface, making it more suitable for applications requiring better wetting ability and surface interactions, particularly in food production. [Figure: see text].

The diamondback moth, Plutella xylostella (L.), is a serious pest of cruciferous crops worldwide and cause serious damage, resulting in up to 90 % yield loss. Heavy dependence on synthetic insecticides has led to widespread resistance and raised environmental concerns, demanding an urgent need for safer, eco-friendly pest control options. In this study, we examined the electrophysiological, behavioural responses of P. xylostella to ten Essential Oils (EOs): Pelargonium hortorum, Ocimum basilicum, Acorus calamus, Trachyspermum ammi, Piper betle, Cymbopogon nardus, Rosmarinus officinalis, Zingiber officinale, Mentha piperita, and Eucalyptus citriodora. Electro Antennogram (EAG) analysis showed that all EOs tested elicited antennal response in adult females; however, R. officinalis, A. calamus, Z. officinale and C. nardus caused significantly higher responses than the other oils tested, and this antennal response aids in host and mate selection. In the behavioural assay using the Y-tube olfactometer revealed that A. calamus, P. betel, Z. officinale, R. officinalis and P. hortorum produced highly significant repellency (P ≤ 0.01). Oviposition assays further revealed that A. calamus, P. hortorum, and Z. officinale at 5% reduced egg laying by 91.78%, 86.9%, and 73.86%, respectively and it was 2.4 to 3.0 times more effective than neem Azadirachta indica. Overall, the results demonstrate robust olfactory and behavioural impacts of several essential oils, particularly A. calamus, Z. officinale and P. hortorum, supporting their potential as botanical repellents or oviposition deterrents for integrated pest management targeting P. xylostella.

This study focuses on investigating the chemical composition and optimizing extraction techniques to produce value-added products from Corymbia citriodora, commonly known as lemon eucalyptus. By analyzing physicochemical parameters, the concentrations of key bioactive compounds-particularly citronellal, citronellol, and isopulegol-were determined to select the most suitable raw materials for further development. Modern extraction methods, including steam distillation and ultrasound-assisted extraction, were evaluated to enhance the recovery of highly active constituents while maintaining compound stability and minimizing degradation. To enhance the recovery of highly active constituents while maintaining compound stability and minimizing degradation, modern extraction methods, including steam distillation and ultrasound-assisted extraction, were systematically evaluated. The research further incorporates structural analysis, chemical profiling, and computational assessment of molecular interactions to explore the potential use of lemon eucalyptus essential oil in natural healthcare products. The findings contribute not only to the valorization of C. citriodora as a rich source of functional phytochemicals but also to the advancement of sustainable extraction strategies, providing a scientific basis for the formulation of safe, effective, and nature-based therapeutic solutions.

IntroductionDust mites are a prevalent indoor allergen contributing to respiratory diseases like allergic rhinitis and asthma. Eucalyptus citriodora essential oil, known for its balsamic odor and repellent effects on various pests, has been scantily investigated for its impacts on dust mites.MethodsThe chemical composition of the essential oil and its head-space extracted from E. citriodora was determined using gas chromatography-mass spectrometry (GC-MS). The toxicity of the oil and its compounds were assessed through contact-fumigant and vapor-phase mortality bioassays. Repellent effects were evaluated using a fabric-contact assay. Data were analyzed using probit regression to determine LC50 values.ResultsThe essential oil contained seven main compounds, and citronellal, citronellol and citronellyl acetate were the most abundant in the oil's volatile, accounting fora total of 88.22%. Citronellal exhibited the highest toxicity, and the essential oil itself showed strong toxicity with the LC50 of 63.94 and 84.53 μL/cm against Dermatophagoides pteronyssinus, 60.72 and 75.88 μL/cm against Dermatophagoides farinae, respectively. In vapor-phase assays, citronellal and ethyl phenylacetate caused 100% mortality.DiscussionCitronellol had the highest repellent effect, and the essential oil, 1,8-cineole, and citronellyl acetate also showed significant repellency rates. E. citriodora essential oil and its compounds particularly citronellal and citronellol, showed high potential for effective dust mite control due to their natural origin, strong toxicity and repellency impacts. Thus, E. citriodora essential oil is a natural, eco-friendly alternative to synthetic acaricides, providing a scientific basis for the control of indoor dust mite allergies.

Wood can be highly susceptible to deterioration by xylophagous agents, which compromises its structural integrity and limits its use in applications involving soil contact. Therefore, evaluating the natural durability of wood is essential to determine its most appropriate uses. The present research aimed to evaluate natural durability as a function of exposure time of 15 species of Eucalyptus and two species of Corymbia, in order to classify wood for use in contact with soil. Two fence posts and stakes of each species were installed in the Floresta Estadual de Manduri, SP. The fence posts of Eucalyptus umbra (broad-leaved white mahogany) and Corymbia citriodora (lemon-scented gum) showed the highest natural durability values, whereas Eucalyptus dunnii (dunn’s gum) and Eucalyptus grandis (rose gum) showed the lowest values. Stakes of Corymbia citriodora (lemon-scented gum) and Corymbia maculata (spotted gum) showed the highest values, whereas Eucalyptus dunnii (dunn’s gum) and Eucalyptus grandis (rose gum), again, showed the lowest values. Overall, fence posts and stakes have good natural durability against exposure up to 7 years; however, after this period, durability decreases considerably. The natural strength of both posts and stakes can be estimated as a function of exposure time with good accuracy. For most species of Eucalyptus and Corymbia, cuttings and posts had an average life exceeding 11 years under our experimental conditions.

Dandruff is a chronic scalp condition and the mildest form of seborrheic dermatitis, associated with microbial dysbiosis primarily involving Malassezia furfur and Staphylococcus epidermidis. Conventional anti-dandruff treatments are often limited by recurrence and reliance on synthetic antifungal agents. This study aimed to develop and evaluate a synergistic, oil-based herbal formulation with antimicrobial activity against dandruff-causing microorganisms. The herbal constituent, Eucalyptus citriodora (EC) oil, individually signifies its efficacy against key dandruff-causing microbes, while Centella asiatica and Wedelia trilobata were included for their complementary bioactive and skin-healing properties. A total of three formulations (F1, F2, and F3), containing 8, 10, and 12% EC oil, respectively, were tested for antimicrobial efficacy. The optimized formulations (F2 and F3) exhibited significant antimicrobial activity, resulting in 1.8–1.9-fold and 2.0–2.5-fold reductions in M. furfur and S. epidermidis cell viability, respectively. Fluorescence-based LIVE/DEAD viability assays and scanning electron microscopy (SEM) confirmed membrane disruption and structural damage in the treated cells of M. furfur. In addition, molecular docking and dynamics simulations demonstrated strong binding affinities of Eucalyptus citriodora oil constituents toward lanosterol 14α-demethylase (LDM), suggesting disruption of the ergosterol biosynthesis pathway as a plausible antifungal mechanism. The obtained findings indicated that the formulated herbal combination exerts a multi-targeted antimicrobial effect and represents a promising natural alternative for controlling microbial populations involved in dandruff pathogenesis.

This study investigated the chemical composition, antioxidant activity, and insecticidal efficacy of essential oils (EOs) and ethanolic extracts (EEs) of Origanum floribundum (OF), Eucalyptus citriodora (EC), and Cymbopogon schoenanthus (CS). EOs were extracted by hydrodistillation and analyzed by GC-MS, while EEs were evaluated for total phenols and flavonoid contents. The antioxidant potential was assessed using DPPH and ABTS, and reducing power assays. The insecticidal activity against Sitophilus oryzae L. (Coleoptera: Curculionidae) was tested through contact and fumigant toxicity. The EOs of OF, EC, and CS were dominated by p-cymene (38.0%), citronellal (40.0%), and piperitone (52.1%), respectively. EEs, particularly that of EC, exhibited superior antioxidant activity (IC50: 7.37 mg/L for ABTS) due to its high phenolic content (217.35 mg GAE/g). In insecticidal assays, the essential oil of CS demonstrated rapid efficacy by fumigation (LT50: 51.78 h), while that from OF exhibited the lowest LC50 (1.51 μL/mL), indicating the best contact toxicity.

An in vitro repellent testing system for use with colony reared black flies, Simulium vittatum, is described. Postoviposition female S. vittatum were exposed to latex membranes treated with 15 μl of commercially available insect repellents every 2 h, up to 12 h. Repellents tested were the following: Repel® Plant-Based Lemon Eucalyptus Insect Repellent 2 (30% oil of lemon eucalyptus [OLE]); OFF!® Botanicals Insect Repellent IV (10% p-menthane-3,8-diol [PMD]); and Zevo™ On-Body (20% 3-[N-butyl-N-acetyl]-aminopropionic acid, ethyl ester, IR3535®). Untreated membranes served as control. The PMD and IR3535 had negative correlations between repellency rate and time (IR3535, m (slopes of mean repellencies over time) = -6.64; and PMD, m = -5.28), whereas OLE had none (m = 0). Statistical analysis demonstrated significance within all groups that included OLE or the control (P < 0.00), but none for groups consisting of PMD or IR3535 (P = 0.31).

Forest ecosystems play an essential role in maintaining biodiversity and mitigating global warming. Intensively managed forest plantations represent a major raw material source for pulp, timber and paper industries. The objective of this study was to apply the model identity test to compare the regression equations used in wood volume estimates of forest species. Five eucalypt species (E. camaldulensis, E. urophylla, E. saligna, E. grandis and E. urograndis) and Corymbia citriodora were evaluated in an experimental area of the Federal University of Mato Grosso do Sul. Five trees in each plot were measured from 56 to 71 months of age to assess the diameter at breast height (DBH) and plant height (Ht), which were later used to estimate the wood volume. The model identity test was applied to evaluate the feasibility of using a single equation to predict the wood volume of all the forest species involved in the study. The complete model had a better fit for the wood volume prediction of the six forest species involved in this study when compared to a single equation. As the tree species studied had different performances in terms of wood volume, species-specific equations should be used to study their growth curves.

Investigating the corrosion inhibition mechanism of Eucalyptus citriodora leaf extract on Q235 carbon steel

In vitro acaricidal effects of essential oils against Rhipicephalus microplus via bioinformatics targeting of triosephosphate isomerase.

Abstract Semi-non-destructive drilling resistance instruments have been widely adopted for timber testing and forestry for wood quality assessments. The accuracy of a drilling resistance tool for predicting wood density may be affected by needle (drill) wear, and there is limited information regarding the wear behaviour of drill bits in wood resistance drilling. It is unknown when changes in needle sharpness and diameter become critical for quantifying wood density. To measure the effect of Resi needle wear, an IML Resi PD 500 was used to obtain cross-sectional traces of Southern Pine (Pinus elliottii var. elliottii (Engelm) × Pinus caribaea var. hondurensis (Sénéclauze)) average outerwood density: 519 kg/m³ and Spotted Gum (Corymbia citriodora subsp. variegata (F. Muell.)) average outerwood density: 779 kg/m³ logs. Southern Pine was tested with feed speeds of 200 cm/min at 3500 rpm and 100 cm/min at 5000 rpm. Spotted Gum was tested with a feed speed of 70 cm/min at 5000 rpm. A new needle was used for each setting. The effect of needle wear was tested after 0, 100, 200, 300, 400, 500, and 600 m of drilling depth. There was no effect on drilling resistance values up to 600 m of drilling length with feed speed 200 cm/min and 3500 rpm settings for Southern Pine. This would result in 2000 drilling measurements of 30 cm diameter trees. With alternative setting for Southern Pine with a setting of 100 cm/min feed speed and 5000 rpm, the increase in amplitudes was not significant until 300 m of drilling, after which, at 400 m, the amplitude increased by 2% (9.8 kg/m3), and after 600 m, the amplitude increased by 3.1% (15.2 kg/m3). For the hardwood Spotted Gum, the amplitude decreased by 0.9% (2.3 kg/m3) after 100 m, and after 300 m, the amplitude decreased by 3.3% (8.2 kg/m3). After 300 m, it was not possible to drill Spotted Gum due to extensive needle wear. The study highlighted the importance of needle wear in resistance drilling, providing guidance for reliable needle use to improve measurement accuracy and wood quality assessment.

This research investigates the bioactive properties of essential oils obtained from three medicinal and aromatic species: Mentha canadensis, Corymbia citriodora, and Plectranthus amboinicus. The essential oils were evaluated for antiviral, antioxidant, anticancer, and antidiabetic activities. The gas chromatography-mass spectrometry (GC–MS) examination identified a variety of phytochemical constituents, including thymol, citronellol, and levomenthol. Cytopathic impact studies indicated that M. canadensis and C. citriodora oils attained a maximum of 35.34% suppression of Adeno 7 virus replication. The oils exhibited minimal cytotoxicity in Vero cells, with viability exceeding 97% at concentrations of ≤ 312 µg/mL. P. amboinicus oil had the highest cytotoxicity against H1299 lung cancer cells (IC50 = 11 µg/mL), indicating significant anticancer efficacy. The antidiabetic effects were evidenced by α-glucosidase inhibition, with P. amboinicus oil displaying the greatest activity (IC50 = 248.1 µg/mL). The DPPH experiment demonstrated that P. amboinicus exhibited the highest antioxidant activity (IC50 = 5923 µg/mL). The results highlight the medicinal potential of these essential oils, including P. amboinicus for anticancer, antioxidant and antidiabetic applications, and C. citriodora and M. canadensisfor antiviral purposes. The current work serves about four goals of the sustainable development goals (SDG) as follow: SDG 3: Good Health and Well-being, SDG 12: Responsible Consumption and Production, SDG 9: Industry, Innovation, and Infrastructure and SDG 15: Life on Land.

Anticoagulant activity of Eucalyptus essential oils: An in vitro approach and a bioinformatics-based pharmacokinetic-pharmacodynamic analysis.

Objective: The aim of this study was to evaluate in vitro the effect of medicinal plants on Candida albicans. Theoretical Framework: Candida albicans is a yeast present in the human microbiota considered as an opportunistic pathogen, which in times of low resistance can invade tissues, organs and even cause systemic diseases. The resistance of C. albicans to antifungals has caused recurrences, requiring the search for therapeutic alternatives, such as the use of herbal medicines. Method: Infusions of Cymbopogom citratus, Citrus limon, Eucalipitus citriodora, Caryophyllus aromaticus and Origanum vulgare on Candida albicans strain were used. Minimum inhibitory and fungicidal concentrations were used in the study. Descriptive statistics was used with the Kruskal-Wallis non-parametric test approach with Dunn's post-hoc multiple comparison test, with 0.05 significance. Results and Discussion: All infusions demonstrated antifungal efficacy against C. albicans, though effectiveness varied significantly by plant species and exposure time. While Citrus limon (lowest MIC: 5%) required extended exposure for complete eradication, Eucalyptus citriodora exhibited rapid initial action. These findings align with prior studies on essential oils but uniquely highlight infusions as accessible alternatives. Synergy studies are warranted to optimize therapeutic potential. Research Implications: Infusions of these plants could serve as low-cost, low-toxicity therapies for candidiasis, especially in resource-limited settings. Future work should validate efficacy in vivo and explore synergistic combinations. Supports Brazil’s policy promoting sustainable use of biodiversity in public health. Originality/Value: First comparative study of infusions (traditional preparation) against C. albicans, revealing time-dependent fungicidal kinetics. Demonstrates that infusions, not just essential oils, have clinical relevance, bridging traditional medicine with evidence-based practice.

Comparative evaluation of the biomass, chemical, and anatomical characteristics for wastewater-irrigated Eucalyptus camaldulensis and Corymbia citriodora

The increasing use of plant-derived insecticides for malaria vector control necessitates comprehensive evaluation of their histopathological effects on target organisms. This study investigated acute (24-hour) and chronic (72-hour) tissue damage in Anopheles gambiae exposed to methanol, ethanol, and ethyl acetate extracts of Eucalyptus citriodora, Azadirachta indica and Albizia lebbeck. Using standardized hematoxylin and eosin staining protocols, we observed severe midgut epithelial vacuolization (mean severity score 4.4±0.5) following acute exposure to methanol extracts, progressing to complete tissue necrosis during chronic exposure. Ethyl acetate extracts demonstrated significantly milder effects (p&lt;0.001), suggesting solvent-dependent toxicity patterns. These findings provide crucial insights into the mechanisms of action of botanical insecticides while highlighting the need for careful consideration of solvent selection in formulation development. The study contributes to the growing body of evidence supporting plant-based alternatives for vector control, particularly in resistance management strategies.

Essential oils (EOs), from plants’ secondary metabolism, present bioactive compounds that may have insecticidal activity. Their use associated with parasitoid hymenoptera can be an alternative, however, little is known about the impact of EOs on the diamondback moth, Plutella xylostella and parasitoids. This work aimed to evaluate the effect of oils from Eucalyptus citriodora (EOEC) and Schinus terebinthifolius (EOST) (0.5% and 1%) on eggs and larvae of P. xylostella and on Trichogramma pretiosum. P. xylostella eggs were immersed in solutions containing EOs and in water (control). Treated cabbage leaf discs were offered to larvae. Eggs with EOs were offered to T. pretiosum females to evaluate parasitism and emergence. Already parasitized P. xylostella eggs were immersed in the treatments to observe the effect on the emergence of parasitoids. The survival of T. pretiosum adults exposed to EOs was recorded. The average number of inviable eggs was higher in treatments with EOs, ranging from 6.9 ± 1.31 to 13.0 ± 1.12 than in the control (3.5 ± 0.32) (p &amp;lt; 0.05). The average number of dead caterpillars was higher in treatments with EOs, ranging from 1.4 ± 0.24 to 2.2 ± 0.19 than in the control (0.1 ± 0.06) (p &amp;lt; 0.05) Leaf consumption in 48 h did not differ between the EOST treatment (0.05) (5.42%) and the control (9.7%). For the other treatments it was significantly lower: 3.8% (EOEC 0.5), 1.6 (EOEC 1), and 3.4 (EOST 1). Eggs treated with EOs prior to exposure to the parasitoid had lower parasitism rates than eggs that were already parasitized and subsequently treated with EOs. The mortality of adults exposed to EOs was 3% to 6%. The EOs of E. citriodora and S. terebinthifolius were toxic to eggs and larvae of P. xylostella, acted as feeding deterrents, and had minimal impact on parasitoids. As a result, they are promising for use in IPM.

Improving technologies for clonal seedling production is essential due to the expansion of forestry production areas. The objective of this study was to assess the impact of managing mini-tunnels in a clonal mini-garden on the productivity and physiological quality of mini-stumps, as well as on the survival and rooting of mini-cuttings of Eucalyptus and Corymbia clones throughout the four seasons. For this purpose, the experiments were conducted in two phases: in the first phase, the clonal mini-garden phase, two clonal mini-gardens were established, one with a mini-tunnel and the other without. Each mini-garden contained mini-stumps of Eucalyptus saligna and hybrid clones of Corymbia torelliana × Corymbia citriodora. During this phase, environmental variables (temperature and relative humidity) were monitored in the cultivation environments (a mini-garden with and without a mini-tunnel), along with productivity and hydrogen peroxide concentration. In the second phase, in the rooting house, survival (%) and rooting (%) were evaluated. The use of mini-tunnels increased environmental variables near the mini-stumps throughout all four seasons. The presence of the mini-tunnel promoted an increase in mini-stump productivity for both genetic materials throughout the year and positively influenced the survival and rooting of mini-cuttings, demonstrating the effectiveness of the structure in mini-stump preconditioning, especially during seasons with lower temperatures. Therefore, the use of mini-tunnels in the clonal mini-garden during autumn and winter is recommended to increase the production of Eucalyptus saligna and Corymbia torelliana × Corymbia citriodora seedlings.

With the objective of combating malaria by reducing the populations of Plasmodium spp vectors, the larvicidal and adulticidal effects of essential oils of Corymbia citriodora (Myrtaceae) and Xylopia aetiopica (Annonaceae) on Anopheles gambiae sensu stricto Giles 1902 were determined. Biological tests were carried out using a methodology inspired by the standard WHO protocol (2005) and revealed that the essential oils tested on larvae and adults of Anopheles gambiae sensu stricto Giles 1902 possess remarkable larvicidal and adulticidal properties. In stage II larvae, LC50 values (ppm) were 27.07 and 42.88 respectively for Corymbia citriodora and Xylopia aetiopica with HL50s of 1h 09min 32sec and 2h 41min 02sec respectively. In stage IV larvae, LC50 values (ppm) were 30.62 (Corymbia citriodora) and 47.85 (Xylopia aetiopica) with HL50s of 1h 40min 25sec and 3h 40min 41sec respectively. Adult LC50s (ppm) for Corymbia citriodora and Xylopia aetiopica were 32.25 and 35.13 respectively. Adult HL50s were 1h 50min 24sec and 2h 11min 46sec. Corymbia citriodora plant oil, which showed correspondingly low LC50s and HL50s, is therefore the most effective compared with Xylopia aetiopica plant oil.