Eucalyptus Viminalis Research Articles

Predicting key water stress indicators of Eucalyptus viminalis and Callitris rhomboidea using high-resolution visible to short-wave infrared spectroscopy.

Drought is one of the main factors contributing to tree mortality worldwide and drought events are set to become more frequent and intense in the face of a changing climate. Quantifying water stress of forests is crucial in predicting and understanding their vulnerability to drought-induced mortality. Here, we explore the use of high-resolution spectroscopy in predicting water stress indicators of two native Australian tree species, Callitris rhomboidea and Eucalyptus viminalis. Specific spectral features and indices derived from leaf-level spectroscopy were assessed as potential proxies to predict leaf water potential (Ψleaf), equivalent water thickness (EWT) and fuel moisture content (FMC) in a dedicated laboratory experiment. New spectral indices were identified that enabled very high confidence linear prediction of Ψleaf for both species (R2 > 0.85) with predictive capacity increasing when accounting for a breakpoint in the relationships using segmented regression (E. viminalis, R2 > 0.89; C. rhomboidea, R2 > 0.87). EWT and FMC were also linearly predicted to a high accuracy (E. viminalis, R2 > 0.90; C. rhomboidea, R2 > 0.80). This study highlights the potential of spectroscopy as a tool for predicting measures of plant water noninvasively, enabling broader applications for monitoring and managing plant water stress.

Potential of using medicinal plant extracts as photosensitizers for antimicrobial photodynamic therapy.

Antimicrobial photodynamic therapy (APDT) is a promising approach to overcome antimicrobial resistance. However, for widespread implementation of this approach, approved photosensitizers are needed. In this study, we used commercially available preparations (Calendulae officinalis floridis extract, Chamomillae recutitae floridis extract, Achillea millefolii herbae extract; Hypericum perforatum extract; Eucalyptus viminalis folia extract) as photosensitizers for inactivation of gram-negative (Pseudomonas aeruginosa) and gram-positive (Staphylococcus aureus) bacteria. Spectral-luminescent analysis has shown that the major chromophores are of chlorophyll (mainly chlorophyll a and b) and hypericin nature. The extracts are efficient generators of singlet oxygen with quantum yield (γΔ ) from 0.40 to 0.64 (reference compound, methylene blue with γΔ = 0.52). In APDT assays, bacteria before irradiation were incubated with extracts for 30 min. After irradiation and 24 h of incubation, colony-forming units (CFU) were counted. Upon exposure of P. aeruginosa to radiation of 405 nm, 590 nm, and 660 nm at equal energy dose of 30 J/cm2 (irradiance - 100 mW/cm2 , exposure time - 5 min), the most pronounced effect is observed with blue light (>3 log10 reduction); in case of S. aureus, the effect is approximately equivalent for light of indicated wavelengths and dose (>4 log10 reduction).

Population assessment of the Endangered Forty-spotted Pardalote Pardalotus quadragintus on Maria Island, Tasmania

The Forty-spotted Pardalote Pardalotus quadragintus is one of the smallest birds in Australia and is endemic to Tasmania, where it occurs only in forest or woodland containing White Gum Eucalyptus viminalis. It is listed as Endangered under the Tasmanian Threatened Species Protection Act 1995 and Commonwealth Environment Protection and Biodiversity Conservation Act 1999. A habitat-stratified survey of Forty-spotted Pardalotes on Maria Island, off the eastern coast of Tasmania, was undertaken in August 2023 to provide a robust estimate of the population. Initial stratification using available vegetation mapping overestimated the availability of suitable habitat based on survey-site habitat evaluations. Forty-spotted Pardalotes were detected at 14 of 74 survey sites, with all detections being at sites where White Gum was the main tree species present. Their mean density was 1.66 birds per hectare, with an estimated total population of 847 birds (CV 0.38, confidence intervals 404–1776 birds). This estimate is consistent with previous uncorrected count-based estimates, although comparisons with historical counts are highly subjective given the substantial methodological differences. Only ~5% of Maria Island supports the preferred habitat for this species and further research on the requirements for, and abundance of, suitable microhabitat is recommended to further refine population estimates and guide conservation management actions.

Variation in xylem vulnerability to cavitation shapes the photosynthetic legacy of drought.

Increased drought conditions impact tree health, negatively disrupting plant water transport which, in turn, affects plant growth and survival. Persistent drought legacy effects have been documented in many diverse ecosystems, yet we still lack a mechanistic understanding of the physiological processes limiting tree recovery after drought. Tackling this question, we exposed saplings of a common Australian evergreen tree (Eucalyptus viminalis) to a cycle of drought and rewatering, seeking evidence for a link between the spread of xylem cavitation within the crown and the degree of photosynthetic recovery postdrought. Individual leaves experiencing >35% vein cavitation quickly died but this did not translate to a rapid overall canopy damage. Rather, whole canopies showed a gradual decline in mean postdrought gas exchange rates as water stress increased. This gradual loss of canopy function postdrought was due to a significant variation in cavitation vulnerability of leaves within canopies leading to diversity in the capacity of leaves within a single crown to recover function after drought. These results from the evergreen E. viminalis emphasise the importance of within-crown variation in xylem vulnerability as a central character regulating the dynamics of canopy death and the severity of drought legacy through time.

Comparison of Hydrogen Production Efficiency by Rhodopseudomonas palustris MP3 and Rhodopseudomonas harwoodiae SP6 Using an Iron Complex as an Enhancement Factor

In the present study, an iron(II)-nanoscale organic complex (Fe-NO) was used as an enhancement factor by two different Rhodopseudomonas species of purple non-sulphur bacteria (PNSB) to produce hydrogen (H2). The Fe-NO complex was synthesised using FeSO4·7H2O and Eucalyptus viminalis—a native Australian plant leaf extract—in a 1:2 and 2:1 concentration ratio. Besides, FeSO4·7H2O was also used as a source of iron(II) for comparison with the Fe-NO complex. The photo-fermentative bacterial cultures were isolated from a fishpond, and only two strains, MP3 and SP6, were found viable after several attempts of quadrate streaking. After phylogenetic analysis, these strains were designated as R. palustris MP3 and R. harwoodiae SP6. After comparison with the control, the results showed that the PNSBs manifested an approximately 50% higher H2 yield when the 1:2 Fe-NO complex was used in the fermentation broth at 10 mg/L concentration, where 10.7 ± 0.54 and 10.0 ± 0.49 mL H2/L were obtained by R. palustris MP3 and R. harwoodiae SP6, respectively. The study revealed that the 1:2 Fe-NO complex could be an important material for efficient H2 production.

Pharmaceutical 3D-printing of nanoemulsified eucalypt extracts and their antimicrobial activity

Overcoming the health threatening consequences of staphylococcal infections and their negative socio-economic effects have become a priority in the medical, pharmaceutical, food and many other sectors globally. Staphylococcal infections are a big challenge for a global health care, since they are difficult to be diagnosed and treated. Therefore, the development of new medicinal products of plant-origin is timely and important, because bacteria have a limited ability to develop resistance to such products. In the present study, a modified eucalypt (Eucalyptus viminalis L.) extract was prepared and further enhanced by using different excipients (surface active agents) to obtain a water-miscible 3D-printable extract (nanoemulsified aqueous eucalypt extract). Phytochemical and antibacterial studies of the eucalypt leaves extracts were conducted as a preliminary investigation for 3D-printing experiments of the extracts. The nanoemulsified aqueous eucalypt extract was mixed with polyethylene oxide (PEO) to form a gel applicable for semi-solid extrusion (SSE) 3D printing. The key process parameters in a 3D-printing process were identified and verified. The printing quality of the 3D-lattice type eucalypt extract preparations was very good, demonstrating the feasibility of using an aqueous gel in SSE 3D printing also exhibiting compatibility of the carrier polymer (PEO) with the plant extract. The SSE 3D-printed eucalypt extract preparations presented a rapid dissolution in water within 10–15 min, suggesting the applicability of these preparations e.g., in oral immediate-release applications.

Deadly acceleration in dehydration of Eucalyptus viminalis leaves coincides with high-order vein cavitation.

Xylem cavitation during drought is proposed as a major driver of canopy collapse, but the mechanistic link between hydraulic failure and leaf damage in trees is still uncertain. Here, we used the tree species manna gum (Eucalyptus viminalis) to explore the connection between xylem dysfunction and lethal desiccation in leaves. Cavitation damage to leaf xylem could theoretically trigger lethal desiccation of tissues by severing water supply under scenarios such as runaway xylem cavitation, or the local failure of terminal parts of the leaf vein network. To investigate the role of xylem failure in leaf death, we compared the timing of damage to the photosynthetic machinery (Fv/Fm decline) with changes in plant hydration and xylem cavitation during imposed water stress. The water potential at which Fv/Fm was observed to decline corresponded to the water potential marking a transition from slow to very rapid tissue dehydration. Both events also occurred simultaneously with the initiation of cavitation in leaf high-order veins (HOV, veins from the third order above) and the analytically derived point of leaf runaway hydraulic failure. The close synchrony between xylem dysfunction and the photosynthetic damage strongly points to water supply disruption as the trigger for desiccation of leaves in this hardy evergreen tree. These results indicate that runaway cavitation, possibly triggered by HOV network failure, is the tipping agent determining the vulnerability of E. viminalis leaves to damage during drought and suggest that HOV cavitation and runaway hydraulic failure may play a general role in determining canopy damage in plants.

Exploring Contact Toxicity of Essential Oils against Sitophilus zeamais through a Meta-Analysis Approach.

Sitophilus zeamais is a primary pest of maize. Our aim was to perform a qualitative review and meta-analyses with 56 scientific articles published from 1 January 2000 to 1 October 2022 dealing with direct (topical application) and indirect (impregnation of essential oils, EOs, onto filter paper or maize grains) contact toxicity of EOs against S. zeamais. Three independent meta-analyses of single means of LD50 (direct contact) and LC50 (indirect contact) were conducted using a random effect model. Essential oils more frequently evaluated were those belonging to Asteraceae, Apiaceae, Lamiaceae, Myrtaceae, Piperaceae, and Rutaceae. The LC50 global mean values were 33.19 µg/insect (CI95 29.81-36.95) for topical application; 0.40 µL/cm2 (CI95 0.25-0.65) for filter paper indirect contact; and 0.50 µL/g maize (CI95 0.27-0.90) for maize grains indirect contact. The species Carum carvi, Salvia umbratica, Ilicium difengpi, Periploca sepium, Cephalotaxus sinensis, Murraya exotica, Rhododendron anthopogonoides, Ruta graveolens, Eucalyptus viminalis, Ocotea odorifera, Eucalyptus globulus, Eucalyptus dunnii, Anethum graveolens, Ilicium verum, Cryptocarya alba, Azadirachta indica, Chenopodium ambrosioides, Cupressus semperivens, Schinus molle, Piper hispidinervum, Mentha longifolia, and Croton pulegiodorus showed LC50 or LD50 values lower than the global means, indicating good insecticidal properties. Our results showed that EOs have great potential to be used as bioinsecticides against S. zeamais.

The effect of gamma-octalactone supplementation on the content of chemical elements in the muscles and liver of broiler chickens

Relevance. In recent years, a large number of new herbal preparations have appeared on the market, including gamma-octalactone. It is a naturally occurring compound isolated from Eucalyptus viminalis leaf extract. This compound has a wide range of therapeutic properties, which is associated with its antiinflammatory, antiseptic effect, stimulates appetite, increases the secretion of digestive enzymes and increases performance in animals.Materials and methods. The paper studied the features of the accumulation of chemical elements in the body tissues of broiler chickens when the compound gamma-octalactone was included in the diet. The studies were carried out on broiler chickens of the Arbor Acres cross at the age of 7–42 days. According to the scheme of the experiment, inthe diet of chickens of the 1st, 2nd and 3rd experimental groups was added gamma-octalactone at a dosages of 0.05, 0.1 and 0.2 ml/kg of b.w./day. The elemental composition of biosubstrates was studied using atomic emission and mass spectrometry.Results. It was found that the addition of gamma-octalactone contributed to the redistribution of chemical elements in the body tissues of the experimental poultry. In particular, the broilers of the experimental group that received gamma-octalactone at a dosage of 0.05 ml/kg of b.w./day had higher concentrations of B, Co, Ni, Se, V, Zn in the pectoral muscles. An analysis of the concentrations of the main essential elements in the thigh muscles of broiler chickens showed that feeding gamma-octalactone at a dosage of 0.05 ml/kg of b.w./day was accompanied by a significant increase in the content of Ca, Na, Fe, Si and Zn and a decrease in the levels of Cr, Cu and Ni relative to poultry of the control group. There was also a significant increase in the concentrations of Cu, Fe, Se, Zn, Mg, P in the liver of chickens of the experimental group, who received gamma-octalactone in the diet at a dosage of 0.1 ml/kg of l.w./day, against the background of a decrease in the concentrations of Si and Na.

Modelling the distribution of a key habitat feature to guide future on‐ground habitat assessment for an endangered specialist songbird

AbstractSpecies distribution models (SDMs) are often used during the planning stage of reintroduction programmes to model species' occurrence with the aim of selecting potential release sites. However, for many endangered species, only a low number of records are available, leading to models with low accuracy. When planning reintroductions for rare species, an alternative approach may be to model surrogate species that are more abundant or easier to locate. Here, we modelled the distribution of white gum (Eucalyptus viminalis), the preferred food tree of the forty‐spotted pardalote (Pardalotus quadragintus), a rare songbird for which reintroduction has been proposed. Using boosted regression trees, we modelled white gum distribution under current and future climate conditions with the aim of identifying areas of high probability of occurrence that later can be used to plan on ground habitat assessments for reintroductions. Our model show areas with high probability of white gum occurrence outside its currently mapped distribution, indicating that there may be opportunities for reintroduction of pardalotes beyond their current range. Predictions of future climate scenarios showed climate space shifts, not only with some decrease but also with substantial increase in the probability of suitability for occurrence under some scenarios. Our spatial predictions for white gum may be used to design a survey to ground‐truth our model and undertake a comprehensive habitat assessment for other habitat features forty‐spotted pardalotes need to persist. The approach used in our study may be used for other highly specialized species, not only in the context of reintroduction planning but also in the general management of data‐poor specialist species that depend on a more common resource.

The Main Aspects of End-to-End Standardisation of Herbal Drugs, Herbal Drug Preparations, and Herbal Medicinal Products of Eucalyptus viminalis

The principle of consistent, end-to-end standardisation builds upon the fact that qualitative and quantitative analysis of bioactive compounds in herbal drugs, herbal drug preparations, and corresponding herbal medicinal products involves the same methods of analysis. The possibility of such standardisation should be considered at the stage of specification development. The aim of the study was to explore approaches to analysing of Eucalyptus viminalis leaves and chlorophyllipt medicinal products, observing the principle of end-to-end standardisation. Materials and methods : the authors analysed Eucalyptus viminalis as a herbal drug (leaves), a herbal drug preparation (chlorophyllipt soft extract), and herbal medicinal products (Chlorophyllipt®, 1% alcohol solution for oral, cutaneous, rectal, and vaginal use; 2% oil solution for cutaneous and vaginal use; and 25 mg orodispersible tablets) by direct UV spectrophotometry, thin-layer chromatography (TLC), and qualitative reactions. Results : the study demonstrated the possibility of using a herbal reference standard of eucalimin to analyse the Eucalyptus viminalis herbal drug and chlorophyllipt preparations and medicinal products in different dosage forms by TLC. Conclusions : procedures for determination of total phenolic aldehydes, if included into specifications and production technology of chlorophyllipt preparations and products, ensure compliance with the principle of end-to-end standardisation and allow for quantitative determination and control of active ingredients throughout the product lifecycle: from the acceptance of raw materials, through in-process controls, to testing and monitoring of finished products’ quality.

Effects of Increasing Fire Frequency on Conservation Values in Eucalyptus Grassy Woodland in the Process of Invasion by Allocasuarina verticillata

Woody thickening is a widespread phenomenon in the grassy woodlands of the world, often with deleterious effects on nature conservation values. We aimed to determine whether increasing the frequency of planned fire prevented woody thickening and improved conservation values in a Eucalyptus viminalis grassy woodland in the process of invasion by Allocasuarina verticillata (henceforth Allocasuarina) in Hobart, Tasmania, Australia. We used a before–after control intervention design. Ten plots from which detailed vegetation data were collected in 2018 (before the burns), 2019 (between burns), 2020 (between burns) and 2021 (after the burns) were randomly located in each of four blocks. Two of the blocks were burned in both 2018 and 2021. One block was burned only in 2021, and another was not burned at all. Mechanical thinning of Allocasuarina took place in 2021 in six plots in one unburned block and in three twice-burned plots. The fires were low intensity and patchy, reflecting the reality of planned burns in this environment. Thus, there were unburned plots mixed with burned plots in each of the three burned blocks. We compared changes in vegetation and cover attributes between a preburn survey in 2018 and a postburn survey in 2021, between five fire history/thinning classes (unburned, no thinning; unburned, thinning; twice burned; burned in 2018 only; burned in 2021 only). Fires in both 2018 and 2021 resulted in lower litter cover and higher exotic species richness than one fire in 2021. Exotic species richness increase between 2018 and 2021 was greater after fires in 2018 and 2021 than after a fire in 2021 alone. Exotic species richness was lowest six years after fire and highest one to three years after fire. The basal area of Allocasuarina was, counter-intuitively, less reduced by two fires in four years than by one. Mechanical thinning reduced shrub layer cover, which largely consisted of small trees, but did not affect basal area. Our data suggested that grass cover increased until five years after a fire, declining back to a low level by eight years. The implications of the results for conservation management are that the mechanical removal of young Allocasuarina may be successful in preventing its thickening and that burning at a five-year interval is likely to best maintain understorey conservation values. The counter-intuitive results related to Allocasuarina basal area emphasise the importance of understanding cumulative effects of fire regimes on fuel cycles and the consequent effects on tree mortality.

Effect of the Eucalyptus viminalis leaf extract compound on the amino acid and fatty acid composition of broiler chicken meat

The article presents the results on evaluating the effect of the gamma-octalactone compound isolated from Eucalyptus viminalis leaf extract on the amino acid and fatty acid composition of protein and lipids of broiler chickens' muscle tissue. The object of the study was 7-day-old broiler chickens of the Arbor Acres cross. During the experiment, the control group poultry consumed the main diet (MD); the poultry of the experimental groups received the main diet plus gamma-octalactone at the following dose: group I – 0.05 ml/kg l.w./ day; II – 0.1 ml/kg l.w./ day; III – 0.2 ml/ kg l.w./day. It was found that the experimental compound's introduction into the diets significantly increases protein and fat content, as well as improves the balance of experimental groups' chicken meat for essential amino acids, as evidenced by a significant increase in the content of leucine and isoleucine - 2.27% (P≤0.01), valine - 0.8% (P≤0.05), phenylalanine 0.44 (P≤0.05) % in chickens of the experimental group III in relation to the control. With a relatively stable amount of saturated fatty acids in the experimental groups, compensation for insufficient synthesis of polyunsaturated fatty acids was observed by increased accumulation of monounsaturated fatty acids. However, despite the existing differences in the concentration of unsaturated fatty acids, no significant intergroup changes were observed.

The effectiveness of acaricidic drugs based on herbal raw material

Limitation the number of ixodes ticks is one of the most important tasks of modern science and requires the search for new, highly effective and environmentally hazardous acaricides, so our experiment was aimed at identifying acaricidal properties of essential oils and their individual active components in the population of ixodes ticks in Zaporizhzhia region. The study of acaricidal properties of essential oils was performed in the laboratory conditions. Tampons with wool were soaked in various concentrations of 0.5%, 1%, 3%, 5% and 10% aqueous emulsion of essential oils such as Caryophyllus floris aetheroleum and Limonis aetheroleum, and essential oils of Thymus serpyllum L., Рinus sylvestris L., Salvia officinalis L., Mentha x piperita L. and Eucalyptus viminalis Labill. The essential oils had a significant effect on the lifespan of adult ticks. The results showed the acaricidal effect of Thymus serpyllum essential oils. When searching the acaricidal and repellent properties of individual essential oils components thymole, menthol and citral showed the high activity as acaricides. In the same time, eugenol and borneol proved the effectiveness as repellent. Our research schowed that essential oils are promising as alternative methods of controlling the number of Ixodes ticks in areas where there are conditions for infection with tick infections.

Sources of phenotypic variation of wood density and relationships with mean growth in two Eucalyptus species in Argentina

Aims of the study: To describe the radial patterns of wood density, and to identify their main sources of variation, and the potential tradeoffs with mean tree growth, in two Eucalyptus species. Area of study: Mesopotamian (Corrientes and Entre Ríos provinces) and Pampean region (Buenos Aires province) of Argentina. Materials and methods: Eucalyptus grandis and Eucalyptus viminalis, growing in genetic trials installed in two sites per species were studied. X-ray wood microdensity profiles were developed from core samples. Each profile was proportionally divided in 10 sections. Mean, maximum, minimum and the standard deviation of wood density, for each section were computed. Mean annual growth was used to study the relationships with wood microdensity variables. A linear mixed-effects model computed the significance of different sources of phenotypic variation. Pearson´s correlation computed the relationships between variables. Main results: The pattern of radial variation in E. grandis showed a decrease in wood density from pith to bark, mainly due to the decrease in minimum wood density, while in E. viminalis, wood density increased towards the outer wood. In both species, the standard deviation of the wood density increased along the radial profile from pith to bark. Significant variation in wood density was explained by site, provenance and clone/family effects. In E. grandis mean, maximum and minimum wood density were negatively correlated with mean growth, whereas in E. viminalis correlations were positive but close to zero. Research highlights: Both the pattern of radial variation of wood density and the relationship between wood density and mean growth were different in the studied Eucalyptus species, and they varied within species depending on the site they were growing and genetic provenance. Keywords: wood microdensity profile; wood properties; wood products; phenotypic plasticity; Eucalyptus grandis; Eucalyptus viminalis.

Scientific evidence for efficiency of medicinal plants in otorhinolaryngology

Objectives to provide scientific evidence for rational use of herbal medicines in otorhinolaryngological practice.
 Material and methods. The study included the following plants: Eucalyptus viminalis leaves, Monarda fistulosa herbs, Melissa officinalis herbs, Echinacea purpurea herbs, Calendula officinalis flowers, rhizomes of Rhodiola rosea, rhizomes of Eleutherococcus senticosus, Glycyrrhiza glabra roots, Macleaya microcarpa herbs, Macleaya cordata herbs, Plantago major leaves, Origanum vulgare herbs, Thymus serpyllum herbs. Phenylpropanoids, flavonoids, euglobals, monoterpene phenols, phenylpropanoids, terpenoids of essential oils, saponins and alkaloids were isolated from the medicinal plants and studied with thin-layer chromatography, spectrophotometry, NMR spectroscopy, mass spectrometry, and various chemical transformations.
 Results. It was scientifically proved that medicinal plants containing such biologically active compounds as phenylpropanoids, flavonoids, euglobals, terpenoid and phenolic components of essential oils, saponins, carotenoids, alkaloids and polysaccharides are useful for otorhinolaryngology. The active substances of the mentioned chemical groups in combination can provide antimicrobial, antifungal, antiviral, anti-inflammatory, regenerating, antihistamine, adaptogenic and immunomodulatory effects.
 Conclusion. The expediency of using medicinal herbal preparations containing euglobals, monoterpene phenols, flavonoids, phenylpropanoids, terpenoids of essential oils, saponins, alkaloids and polysaccharides in otorhinolaryngological practice was scientifically justified.

Fundamental dietary specialisation explains differential use of resources within a koala population.

The diets of individual animals within populations can differ, but few studies determine whether this is due to fundamental differences in preferences or capacities to eat specific foods, or to external influences such as dominance hierarchies or spatial variation in food availability. The distinction is important because different drivers of dietary specialisation are likely to have different impacts on the way in which animal populations respond to, for example, habitat modification. We used a captive feeding study to investigate the mechanisms driving individual dietary specialisation in a population of wild koalas (Phascolarctos cinereus) in which individuals predominantly ate either Eucalyptus viminalis or Eucalyptus obliqua foliage. All six koalas that primarily ate E. viminalis in the wild avoided eating E. obliqua for more than 1 month in captivity. In contrast, all seven koalas that primarily ate E. obliqua could be maintained exclusively on this species in captivity, although they ate less from individual trees with higher foliar concentrations of unsubstituted B-ring flavanones (UBFs). Our results show that fundamental differences between individual animals allow some to exploit food resources that are less suitable for others. This could reduce competition for food, increase habitat carrying capacity, and is also likely to buffer the population against extinction in the face of habitat modification. The occurrence of fundamental individual specialisation within animal populations could also affect the perceived conservation value of different habitats, translocation or reintroduction success, and population dynamics. It should therefore be further investigated in other mammalian herbivore species.

Coumarin's Anti-Quorum Sensing Activity Can Be Enhanced When Combined with Other Plant-Derived Small Molecules.

Coumarins are class of natural aromatic compounds based on benzopyrones (2H-1-benzopyran-2-ones). They are identified as secondary metabolites in about 150 different plant species. The ability of coumarins to inhibit cell-to-cell communication in bacterial communities (quorum sensing; QS) has been previously described. Coumarin and its derivatives in plant extracts are often found together with other small molecules that show anti-QS properties too. The aim of this study was to find the most effective combinations of coumarins and small plant-derived molecules identified in various plants extracts that inhibit QS in Chromobacterium violaceum ATCC 31532 violacein production bioassay. The coumarin and its derivatives: 7-hydroxycoumarin, 7.8-dihydroxy-4-methylcoumarin, were included in the study. Combinations of coumarins with gamma-octalactone, 4-hexyl-1.3-benzenediol, 3.4.5-trimethoxyphenol and vanillin, previously identified in oak bark (Quercus cortex), and eucalyptus leaves (Eucalyptus viminalis) extracts, were analyzed in a bioassay. When testing two-component compositions, it was shown that 7.8-dihydroxy-4-methylcoumarin, 4-hexyl-1.3-benzendiol, and gamma-octalactone showed a supra-additive anti-QS effect. Combinations of all three molecules resulted in a three- to five-fold reduction in the concentration of each compound needed to achieve EC50 (half maximal effective concentration) against QS in C. violaceum ATCC 31532.

Effect of Essential Oils on the Release of TNF-α and CCL2 by LPS-Stimulated THP‑1 Cells.

Plants and their constituents have been used to treat diverse ailments since time immemorial. Many plants are used in diverse external and internal formulations (infusions, alcoholic extracts, essential oils (EOs), etc.) in the treatment of inflammation-associated diseases, such as those affecting the respiratory tract or causing gastrointestinal or joint problems, among others. To support the traditional uses of plant extracts, EOs have been assessed for their alleged anti-inflammatory properties. However, the effect of EOs on the release of cytokines and chemokines has been much less reported. Considering their traditional use and commercial relevance in Portugal and Angola, this study evaluated the effect of EOs on the in vitro inhibition of the cytokine tumor necrosis factor-α (TNF-α) and the chemokine (C-C motif) ligand 2 (CCL2) by lipopolysaccharide (LPS)-stimulated human acute monocytic leukemia cells (THP-1 cells). Twenty EOs extracted from eighteen species from seven families, namely from Amaranthaceae (Dysphania ambrosioides), Apiaceae (Foeniculum vulgare), Asteraceae (Brachylaena huillensis, Solidago virgaurea), Euphorbiaceae (Spirostachys africana), Lamiaceae (Lavandula luisieri, Mentha cervina, Origanum majorana, Satureja montana, Thymbra capitata, Thymus mastichina, Thymus vulgaris, Thymus zygis subsp. zygis), Myrtaceae (Eucalyptus globulus subsp. maidenii, Eucalyptus radiata, Eucalyptus viminalis) and Pinaceae (Pinus pinaster) were assayed for the release of CCL2 and TNF-α by LPS-stimulated THP-1 cells. B. huillensis, S. africana, S. montana, Th. mastichina and Th. vulgaris EOs showed toxicity to THP-1 cells, at the lowest concentration tested (10 μg/mL), using the tetrazolium dye assay. The most active EOs in reducing TNF-α release by LPS-stimulated THP-1 cells were those of T. capitata (51% inhibition at 20 μg/mL) and L. luisieri (15–23% inhibition at 30 μg/mL and 78–83% inhibition at 90 μg/mL). L. luisieri EO induced a concentration-dependent inhibition of CCL2 release by LPS‑stimulated THP-1 cells (23%, 54% and 82% inhibition at 10, 30 and 90 μg/mL, respectively). These EOs are potentially useful in the management of inflammatory diseases mediated by CCL2 and TNF‑α, such as atherosclerosis and arthritis.

UPLC-PDA-Q Exactive Orbitrap-MS profiling of the lipophilic compounds product isolated from Eucalyptus viminalis plants

The lipophilic compounds product (LCP), which was isolated and purified from Eucalyptus viminalis plants, has shown earlier broad antimicrobial and anti-inflammatory activities. To study secondary compounds responsible for the pharmacological activities, chemical composition of the LCP was studied with application of ultra-performance liquid chromatography combined with photodiode array detector and high-resolution Q Exactive Orbitrap mass spectrometer (UPLC-PDA-HRMS/MS). There were found thirty two compounds: twenty phloroglucinol derivatives (isopentyl diformyl phloroglucinol, macrocarpals, sideroxylonals, etc.), eight ursane type triterpenoids (loxanic acid, dehydroursolic acid lactone, dehydroursolic acid lactone acetate, two isomers of p-coumaroyl-dehydroursolic acid lactone and two isomers of feruloyl-dehydroursolic acid lactone), sequiterpenoid (S)-β-macrocarpene and three unknown phenolics. The major compounds of the LCP were pharmacologically active macrocarpals A and B, dehydroursolic acid lactone and its derivatives. It is supposed that previously discovered antimicrobial and anti-inflammatory activities of the LCP is due to the high contents of these secondary compounds.