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Eucalyptus grandis × E. urophylla was a unique hybridization in China. However, the chemical and pharmacological properties were rarely reported. Therefore, in this work, we used a steam distillation method to obtain essential oils from leaves of E. grandis × E. urophylla, and further evaluated the antioxidant, antimicrobial, and phytotoxic potential of the essential oil. Gas chromatography mass spectrometry (GC-MS) was applied to investigate the chemical composition of E. grandis × E. urophylla essential oil (EEO) and the results showed that the main components of EEO were monoterpenes followed by sesquiterpenes. Among them, α-pinene accounted about 17.02%. EEO could also well scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2, 2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radicals showing a good free radical clearance ability. In addition, EEO efficiently inhibited the growth of six kinds of bacteria as well as seven kinds of plant pathogens, especially Salmonella typhimurium and Colletotrichum gloeosporioides. Moreover, the seedling germination of Raphanus sativus, Lactuca sativa, Lolium perenne, and Bidens pilosa was significantly suppressed by EEO, thus, indicating essential oils from eucalyptus possessed an excellent phytotoxic activity. This study may give a better understanding on EEO and provide a pharmacological activities analysis contributing to the further research of EEO as a functional drug in agronomic and cosmetic industries.

Eucalyptus maideni F. v. Muell., a rare species cultivated for both oil and timber, yields high-quality wood and economically valuable eucalyptus oil (EO). Previous studies revealed substantial variation in leaf oil content among individual seedlings and families. However, the selection and breeding of superior germplasm for oil production have not yet been initiated. In this study, 15 superior trees were used as seed trees, while commercial seeds served as the controls. Seedlings were sown in family groups, and leaves from seed trees and 480 seedlings (sampled at 180 and 360 days post-sowing) were analyzed. EO was extracted from seed tree leaves by steam distillation and from seedling leaves by headspace solid-phase microextraction, with gas chromatography-mass spectrometry (GC–MS) used for component quantification. Among 249 compounds identified, 1,8-cineole (eucalyptol) consistently exhibited the highest relative content (40.61–71.27%). Significant differences in eucalyptol content were found among families and individuals at both seedling ages, with a coefficient of variation (CV) of approximately 25%. Eucalyptol content at both 180 and 360 days was primarily influenced by within-family variance (56.91% and 62.43%, respectively), exceeding between-family variance (42.13% and 36.73%). Additionally, moderate correlations between eucalyptol concentrations at 180 and 360 days suggest partial temporal stability in essential oil composition across developmental stages. Therefore, the relative eucalyptol content was identified as a key indicator for the preliminary selection of superior germplasm in oil-producing E. maideni . Using the mean + standard deviation ( C  + σ) as the selection threshold, two superior families (Families 2 and 3) and 56 elite seedlings were preliminarily identified across both growth stages. The selected superior families exhibited an average increase of 29.85% in leaf eucalyptol content, while the elite seedlings showed an average increase of 37.61%. These results demonstrate the feasibility and effectiveness of early selection for superior germplasm in oil-producing E. maideni . The selected superior germplasm provides foundational material for the subsequent propagation of improved varieties, thereby supporting the development of the oil-producing E. maideni industry in Yunnan Province.

Eucalyptus (Eucalyptus camaldulensis) and Myrrh (Commiphora Myrrha) essential oils (EOs) stand out for their benefits in terms of health and functionality. Buffalo set yogurt enriched with different concentrations of EOs (0.3, 0.6, and 0.9%) were investigated. The effects of addition on sensory, syneresis, antibacterial activity, and bioactive properties (total phenol content and antioxidant activity) of yogurt were studied. The most acceptable organoleptic properties of treated yogurt were those samples treated with Eucalyptus oil. The levels of syneresis were decreased by increasing the concentration of EOs. Moreover, the antioxidant activity, antibacterial activity, and total phenolic content were enhanced by increasing the concentration of EOs. Yogurt with 0.9% Eucalyptus oil showed the highest antioxidant activity and total phenolic content. The same concentration of Eucalyptus oil showed the highest antibacterial activity against S. typhimurium (the inhibition zone was 20.63 mm) then E. coli (the inhibition zone was 19.43 mm). On the other hand, the highest antibacterial effect against L. monocytogene was for Myrrh oil-enriched yogurt by 0.9% and the inhibition zone was 19.21 mm. The obtained results showed that Eucalyptus and Myrrh oils can be applied to yogurt to improve its beneficial properties in terms of physical characteristics and for human health due to their antioxidant activity and phenolic materials.

Some forest trees have been polyploidized to improve their traits and to supply new germplasms for breeding programs. As trees have a long juvenile stage, the early characterization of the chromosome set doubling effects is crucial for previous selection. Thus, we aimed to characterize the chemical variability of essential oils from diploid and autotetraploid germplasms (autotetraploid A and B) of Eucalyptus benthamii , as well as to evaluate their larvicidal and allelopathic effects. Autotetraploid A showed a higher essential oil yield than diploid and autotetraploid B, which did not differ quantitatively. Aromadendrene, viridiflorol and α-pinene were the major compounds in the diploid essential oil. In contrast, compounds were present in autotetraploids, such as 1,8-cineole, limonene, α-terpineol, and α-terpinyl-acetate. Essential oils from the diploid at 50–200 ppm were twice as larvicidal than those from autotetraploids against Aedes aegypti larvae. Considering the phytotoxicity bioassays using Lactuca sativa , essential oils from both ploidy levels affected root growth. Moreover, the essential oils inhibited shoot growth at all concentrations tested (187.5; 375; 750; 1500; and 3000 ppm). Autotetraploid A and B had the same effect on shoot growth as glyphosate. The essential oils had no cytogenotoxic effect on root meristematic cells of L. sativa, whereas phytotoxic potential was identified mainly in shoot growth. This work demonstrated a dramatic change in secondary metabolism (terpene composition) related to an increase in the ploidy level in Eucalyptus germplasms. In addition, we report the novelty of the chemical composition of essential oils among germplasms and their potential use as larvicidal and post-emergence weed control agents.

Eucalyptus is well reputed for its use as medicinal plant around the globe. The present study was planned to evaluate chemical composition, antimicrobial and antioxidant activity of the essential oils (EOs) extracted from seven Eucalyptus species frequently found in South East Asia (Pakistan). EOs from Eucalyptus citriodora, Eucalyptus melanophloia, Eucalyptus crebra, Eucalyptus tereticornis, Eucalyptus globulus, Eucalyptus camaldulensis and Eucalyptus microtheca were extracted from leaves through hydrodistillation. The chemical composition of the EOs was determined through GC-MS-FID analysis. The study revealed presence of 31 compounds in E. citriodora and E. melanophloia, 27 compounds in E. crebra, 24 compounds in E. tereticornis, 10 compounds in E. globulus, 13 compounds in E. camaldulensis and 12 compounds in E. microtheca. 1,8-Cineole (56.5%), α-pinene (31.4%), citrinyl acetate (13.3%), eugenol (11.8%) and terpenene-4-ol (10.2%) were the highest principal components in these EOs. E. citriodora exhibited the highest antimicrobial activity against the five microbial species tested (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Aspergillus niger and Rhizopus solani). Gram positive bacteria were found more sensitive than Gram negative bacteria to all EOs. The diphenyl-1-picrylhydazyl (DPPH) radical scavenging activity and percentage inhibition of linoleic acid oxidation were highest in E. citriodora (82.1% and 83.8%, respectively) followed by E. camaldulensis (81.9% and 83.3%, respectively). The great variation in chemical composition of EOs from Eucalyptus, highlight its potential for medicinal and nutraceutical applications.

Green nanomaterials are increasingly used to improve plant growth and phytochemical traits. This study employed Eucalyptus globulus leaf extract, a medicinal plant, as a bio-reductant and capping agent to synthesize copper oxide nanoparticles (CuO-NPs), which were applied as seed primers for Lactuca sativa (lettuce), an annual species prized for its short germination time and rich bioactive compounds. Characterization of CuO-NPs using FTIR, XRD, SEM, and EDX confirmed their purity, crystalline structure, and an average particle size of 74.66 nm. The CuO-NPs were applied at concentrations of 0.01 mg/ml, 0.02 mg/ml, 0.03 mg/ml, and 0.04 mg/ml. At the highest concentration (0.04 mg/ml), significant reductions in physical growth parameters were observed, with plant length, height, and width measuring 7.85 cm, 5.50 cm, and 3.48 cm, respectively, compared to 13.70 cm, 11.52 cm, and 11.18 cm in control plants. Phytochemical analysis identified tannins, alkaloids, phytosterols, saponins, flavonoids, and glycosides in all methanolic extracts, while carotenoids were absent at higher concentrations (0.03 mg/ml and 0.04 mg/ml) due to phytotoxicity. FTIR analysis revealed a prominent peak at 858 cm⁻¹ at 0.01 mg/ml, indicating the presence of antioxidant-rich aromatic phenyl compounds. In conclusion, the study demonstrates that CuO-NPs synthesized using Eucalyptus globulus extract enhance phytochemical constituents at optimal concentrations but inhibit growth and reduce key phytochemicals at higher doses. Future research should optimize nanoparticle concentrations to minimize phytotoxicity while maximizing beneficial effects on plant growth and bioactive compounds.

The green synthesis of metal oxide nanoparticles is presented as an excellent sustainable alternative for achieving nanostructures, with potential applications. This research provides important information regarding the influence of the type of solvent used in extracting organic reducing agents from E. globulus on the FeO NPs green synthesis protocol. A broad approach to characterization is presented, where UV-vis spectrophotometry suggests the presence of this type of nanoparticulate material. Likewise, the reduction mechanism was evaluated by FT-IR and the magnetic properties were evaluated by PPSM. In addition, characterizations were linked via elemental analysis (EDX), crystallographic characterization (XRD), electron microscopy (SEM/STEM), and Z potential to evaluate colloidal stability. The results show the influence of the type of solvent used for the extraction of organic reducing agents from E. globulus, and the effect on the synthesis of FeO NPs. In addition, the nanostructure material obtained showed excellent efficiency in the remediation of agricultural soil, eliminating metals such as Cr-VI, Cd, and, to a lesser extent, Pb.

Eucalyptus globules belonging to the Myrtaceae family was explored for the synthesis of zinc oxide nanoparticles and for biological applications. The aqueous extract of the synthesized zinc nanoparticles (ZnNPs) was characterized using UV-visible spectrophotometer, FTIR, SEM and TEM. The aqueous broth was observed to be an efficient reducing agent, leading to the rapid formation of ZnNPs of varied shapes with sizes ranging between 52–70 nm. In addition, antifungal activity of the biosynthesized ZnNPs was evaluated against major phytopathogens of apple orchards. At 100 ppm of ZnNPs, the fungal growth inhibition rate was found to be 76.7% for Alternaria mali, followed by 65.4 and 55.2% inhibition rate for Botryosphaeria dothidea and Diplodia seriata, respectively. The microscopic observations of the treated fungal plates revealed that ZnNPs damages the topography of the fungal hyphal layers leading to a reduced contraction of hyphae. This considerable fungicidal property of ZnNPs against phytopathogenic fungi can have a tremendous impact on exploitation of ZnNPs for fungal pest management and ensure protection in fruit crops.

The present study aimed to characterize the chemical composition of pyroligneous acid (PA) obtained from slow pyrolysis of the clone GG100 of Eucalyptus urophylla × Eucalyptus grandis. The efficiency of extraction of organic compounds by using different solvents—dichloromethane (DCM), diethyl ether (DE) and ethyl acetate (EA)—was evaluated. Wood discs were collected and carbonized at a heating rate of 1.25 °C/min until 450 °C. Pyrolysis gases were trapped and condensed, yielding a crude liquid product (CLP), which was refined to obtain pure PA. Then liquid–liquid extraction was carried out. Each extracted fraction was analyzed by GC-MS and the chemical compounds were identified. Experimental results showed that a larger number of chemical compounds could be extracted by using DCM and EA in comparison to diethyl ether DE. A total number of 93 compounds were identified, with phenolic compounds being the major group, followed by aldehydes and ketones, furans, pyrans and esters. Higher contents of guaiacol, phenol, cresols and furfural seem to explain the antibacterial and antifungal activity shown by PA, as reported previously in the literature. Experimental data indicated that the organic phase extracted from GG100 PA consists of a mixture of compounds similar to liquid smokes regularly used in the food industry.

Urea is the most popular and widely used nitrogenous fertilizer. High soil urease activity rapidly hydrolyses applied urea to ammonia which contributes to soil nitrogen (N) losses and reduces N use efficiency of crop plants. The ammonia losses can be minimized by the inhibition of soil urease activity which has been explored using various potential chemical inhibitors. However, the soil urease activity inhibition potential of plant extracts is rarely explored to date. In the present study, extracts of 35 plant materials were taken and evaluated against jack bean urease. Eleven extracts, showing >50% jack bean urease inhibition, were selected and further investigated in 13 soils collected from various districts of Punjab, Pakistan. Interestingly, except Capsicum annum , Melia azedarach , Citrus reticulata and Quercus infectoria , the plant extracts showed urease inhibition activities in soils, the extent of which was lower as compared to that observed in jack bean urease though. Maximum urea hydrolysis inhibition (70%) was noted with Vachellia nilotica which was 40% more than that of hydroquinone (50%) followed by that of Eucalyptus camaldulensis (24%). The extracts of V . nilotica and E . camaldulensis were coated on urea and applied to soil in the next step. At 21 st day, 239% and 116% more urea-N was recovered from soil treated with V . nilotica and E . camaldulensis extracts coated urea, respectively, as compared to uncoated urea. Conclusively, these results indicated that the coating of V . nilotica and E . camaldulensis extracts on urea prills prolonged urea persistence in soil owing to minimum urea hydrolysis, probably, the extracts of V . nilotica and E . camaldulensis showed their urease inhibition potential. The results of this study provide a base line for the identification of new soil urease inhibitor compounds from plant materials in future.