Fabrication of biodegradable and antibacterial films of chitosan/polyvinylpyrrolidone containing Eucalyptus citriodora extracts.

The main objective of this work is to develop biodegradable active films through the combination of the extracts with different solvents sourced from Eucalyptus citriodora leaves, with films made of chitosan (Cs) and polyvinylpyrrolidone (PVP). Chromatographic profiling investigations were carried out to examine the antibacterial characteristics of E. citriodora extracts before their direct incorporation into the polymer films. At this point, the potent antimicrobial properties of the phenol compounds and bioactive components demonstrated an antibacterial activity that was particularly noticeable at a hexane resolution. Different morphological characteristics were seen on films made from these solvent extracts, such as Cs/PVP-AE, Cs/PVP-EAE, and Cs/PVP-HE, when scanning electron microscopy was used. Numerous other outcomes of all the interactions between the extract particles and the film were shown by the pores defined by the Cs/PVP film's porous nature. The addition of the extracts, either alone or in combination, greatly enhanced the Cs/NC/PVP films' mechanical characteristics. It has also been shown that adding plant extracts greatly increased the antibacterial activity of these films. These findings reveal that Cs/PVP films loaded with extract may be utilized as more environmentally acceptable substitutes for possible food packaging application by increasing shelf life of food products.

Formyl phloroglucinol meroterpenoids from the leaves of Eucalyptus globulus subsp. maidenii and their ATP-citrate lyase inhibitory activities.

Three new formyl phloroglucinol meroterpenoids, eumaidials A-C (1-3), were isolated from the leaves of Eucalyptus globulus subsp. maidenii, along with ten known analogues (4-13). Their chemical structures were determined by various spectral data and electronic circular dichroism calculations. Eumaidial A (1) is the first ß-caryophyllene-based formyl phloroglucinol meroterpenoids from the genus Eucalyptus. Compounds 1-4 and 10 exhibited ATP-citrate lyase inhibitory activities, and compounds 2 and 3 suppressed the hepatocyte lipogenesis.

Chemical Composition, Antibacterial Properties, and Anti-Enzymatic Effects of Eucalyptus Essential Oils Sourced from Tunisia.

This study was conducted to examine the chemical composition of the essential oils (EOs) from six Tunisian Eucalyptus species and to evaluate their anti-enzymatic and antibiofilm activities. The EOs were obtained through hydro-distillation of dried leaves and subsequently analyzed using GC/MS. The main class of compounds was constituted by oxygenated monoterpenes, particularly prominent in E. brevifolia (75.7%), E. lehmannii (72.8%), and E. woollsiana (67%). Anti-enzymatic activities against cholinesterases, α-amylase, and α-glucosidase were evaluated using spectrophotometric methods. Notably, the E. brevifolia, E. extensa, E. leptophylla, E. patellaris, and E. woollsiana EOs displayed potent acetylcholinesterase (AChE) inhibition (IC50: 0.25-0.60 mg/mL), with E. lehmannii exhibiting lower activity (IC50: 1.2 mg/mL). E. leptophylla and E. brevifolia showed remarkable α-amylase inhibition (IC50: 0.88 mg/mL), while E. brevifolia and E. leptophylla significantly hindered α-glucosidase (IC50 < 30 mg/mL), distinguishing them from other EOs with limited effects. Additionally, the EOs were assessed for their anti-biofilm properties of Gram-positive (Staphylococcus aureus and Listeria monocytogenes) and Gram-negative (Acinetobacter baumannii, Pseudomonas aeruginosa and Escherichia coli) bacterial strains. The E. extensa EO demonstrated the main antibiofilm effect against E. coli and L. monocytogenes with an inhibition > 80% at 10 mg/mL. These findings could represent a basis for possible further use of Eucalyptus EOs in the treatment of human microbial infections and/or as a coadjutant in preventing and treating Alzheimer's disease and/or diabetes mellitus.

Economic potential of essential oil production from New Zealand-grown Eucalyptus bosistoana.

Farm foresters and other growers are establishing a ground-durable hardwood resource, including the emerging plantation species Eucalyptus bosistoana in New Zealand. The foliage of this species contains essential oils in quantity and quality suitable for commercial extraction. Essential oil production could improve the economic viability of E. bosistoana plantations, diversifying the grower's income and providing an early revenue stream. This study assessed the economic potential for essential oil production from New Zealand grown E. bosistoana plantations. A sensitivity analysis indicated that uncertainty of leaf biomass availability, genetic as well as seasonal changes in oil content, and fluctuations in essential oil price are equally important on the viability of an essential oil operation. Small-scale essential oil production could be sustainably supplied with foliage from thinning and pruning operations sourced from the envisaged regional planting programmes and commence in 3-5 years. A large-scale operation could be supplied when trees will be harvested. Lastly, based on the operational costs of a domestic small-scale essential oil producer, oil value from E. bosistoana would exceed the cost of production.

Comparison of Chemical Compositions and Antioxidant Activity of Essential Oils from Litsea Cubeba, Cinnamon, Anise, and Eucalyptus.

The purpose of this study was to compare the antioxidant activity of litsea cubeba oil (LCO), cinnamon oil (CO), anise oil (AO), and eucalyptus oil (EUC) in vitro. The chemical compositions of the essential oils (EOs) were analyzed using gas chromatography-mass spectrometry (GC-MS). The antioxidant activity of the four EOs was evaluated through scavenging DPPH free radicals, chelating Fe2+, scavenging hydroxyl free radicals, and inhibiting yolk lipid peroxidation. The results showed that the major compounds found in LCO, CO, AO, and EUC are citral (64.29%), cinnamaldehyde (84.25%), anethole (78.51%), and 1,8-cineole (81.78%), respectively. The four EOs all had certain antioxidant activity. The ability to scavenge DPPH radical was ranked in the order of LCO > CO > AO > EUC. The hydroxyl radical scavenging ability was ranked in the order of EUC > CO > LCO > AO. The chelating Fe2+ capacity was ranked in the order of EUC > AO > CO > LCO. The yolk lipid peroxidation inhibition ability was ranked in the order of CO > AO > EUC > LCO. In different antioxidant activity assays, the antioxidant activity of the EOs was different. It was speculated that the total antioxidant activity of an EO may be the result of the joint action of different antioxidant capacities.

Anti-inflammatory mechanisms of eucalyptol rich Eucalyptus globulus essential oil alone and in combination with flurbiprofen.

Inflammation is the core contributor in the pathogenesis of various acute and chronic illness including appendicitis, bronchitis, arthritis, cancer and neurological diseases. NSAIDs, commonly used medications for inflammatory diseases, on prolonged use cause GI bleeding, ulcers and many more issues. Plant-based therapeutic agents including essential oils in combination with low-dose synthetic drugs have been shown to produce synergistic effects and reduce complications of synthetic drugs. This study was designed to evaluate the anti-inflammatory, analgesic and anti-pyretic properties of Eucalyptus globulus essential oil alone and in combination with flurbiprofen. GC-MS analysis was performed to screen chemical composition of oil. In vitro anti-inflammatory assay (membrane stabilization assay) and in vivo inflammatory acute (carrageenan and histamine-induced paw oedema) and chronic (cotton pellet-induced granuloma and Complete Freund's adjuvant-induced arthritis) models were performed to check anti-inflammatory properties. Acetic acid-induced algesia and yeast-induced pyrexia models were performed to check analgesic and anti-pyretic properties. qRT-PCR was performed to study the effect of treatments on the expression of inflammatory biomarkers. GC-MS analysis of E. globulus essential oil showed the presence of eucalyptol along with other active biomolecules. 500 + 10 mg/kg of oil-drug combination showed significantly (p < 0.05) better in vitro membrane stabilization effects as compared with groups treated with 500 mg/kg of E. globulus oil and 10 mg/kg of Flurbiprofen alone. 500 + 10 mg/kg of oil-drug combination showed significantly (p < 0.05) better anti-inflammatory, analgesic and antipyretic effects as compared to 500 mg/kg of E. globulus oil alone in all in vivo models. When comparison was done between 500 + 10 mg/kg of oil-drug combination-treated and 10 mg/kg Flurbiprofen-treated group, the former group showed significantly (p < 0.05) better anti-inflammatory and anti-pyretic effects, but there were non-significant differences in the analgesic model. Animal group treated with 10 mg/kg of Flurbiprofen showed significantly (p < 0.05) better anti-inflammatory and analgesic effects than group treated with 500 mg/kg of oil alone while, there were non-significant differences in anti-pyretic effects. qRT-PCR analysis showed significant (p < 0.05) down-regulation in the expression of IL-4 and TNF-α in serum samples of animals treated with 500 + 10 mg/kg of oil-drug combination as compared to the diseased control (arthritic) group. Overall, the current research demonstrates that Eucalyptus globulus essential oil in combination with flurbiprofen showed better anti-inflammatory, analgesic and anti-pyretic effects than oil and flurbiprofen alone which is attributed to the down-regulation of pro-inflammatory biomarkers (IL-4 and TNF-α). Further studies are required to formulate a stable dosage form and to check the anti-inflammatory efficacy in different inflammatory disorders.

Chemical Composition, Antioxidant and Antibacterial Activities and Acute Toxicity of Cedrus atlantica, Chenopodium ambrosioides and Eucalyptus camaldulensis Essential Oils.

The essential oils yield of Cedrus atlantica, Chenopodium ambrosioides and Eucalyptus camaldulensis was different. C. ambrosioides gave a relatively higher yield (2.1 ± 0.1%), while that of C. atlantica was low (1.0 ± 0.1%) and that of E. camaldulensis was lower (0.75 ± 0.1% of dry matter). The active ingredients of the essential oils and some of their biological effects were also determined. The characterization of their chemical compositions showed that the three essences have different chemical profiles: C. atlantica was richer in sesquiterpenes (ß-Himachalene (54.21%) and γ -Himachalene (15.54%)), C. ambrosioides was very rich in monoterpene peroxides and monoterpenes (α-Terpinene (53.4%), ascaridole (17.7%) and ρ-Cymene (12.1%)) and E. camaldulensis was very rich in monoterpene compounds and monoterpenols (p-cymene (35.11%), γ-Eudesmol (11.9%), L-linalool (11.51%) and piperitone (10.28%)). The in vitro measurement of antioxidant activity by the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) reduction assay showed a significant performance of the eucalyptus oil and average performance of the other two (C. atlantica and C. ambrosioides). The in vitro bio-test for their antimicrobial effects showed that the antibacterial activity differed depending on the essential oil and the concentration used, and that their bactericidal efficacy was similar or superior to that of synthetic antibiotics. The toxicity test on rats revealed that the LD50 of the three essential oils was 500 mg/kg body weight, which classifies them as category four cytotoxic natural products at high doses.

Exploiting the Integrated Valorization of Eucalyptus globulus Leaves: Chemical Composition and Biological Potential of the Lipophilic Fraction before and after Hydrodistillation.

E. globulus leaves have been mainly exploited for essential oil recovery or for energy generation in industrial pulp mills, neglecting the abundance of valuable families of extractives, namely, triterpenic acids, that might open new ways for the integrated valorization of this biomass. Therefore, this study highlights the lipophilic characterization of E. globulus leaves before and after hydrodistillation, aiming at the integrated valorization of both essential oils and triterpenic acids. The lipophilic composition of E. globulus leaves after hydrodistillation is reported for the first time. Extracts were obtained by dichloromethane Soxhlet extraction and analyzed by gas chromatography-mass spectrometry. In addition, their cytotoxicity on different cell lines representative of the innate immune system, skin, liver, and intestine were evaluated. Triterpenic acids, such as betulonic, oleanolic, betulinic and ursolic acids, were found to be the main components of these lipophilic extracts, ranging from 30.63-37.14 g kg-1 of dry weight (dw), and representing 87.7-89.0% w/w of the total content of the identified compounds. In particular, ursolic acid was the major constituent of all extracts, representing 46.8-50.7% w/w of the total content of the identified compounds. Other constituents, such as fatty acids, long-chain aliphatic alcohols and ß-sitosterol were also found in smaller amounts in the studied extracts. This study also demonstrates that the hydrodistillation process does not affect the recovery of compounds of greatest interest, namely, triterpenic acids. Therefore, the results establish that this biomass residue can be considered as a promising source of value-added bioactive compounds, opening new strategies for upgrading pulp industry residues within an integrated biorefinery context.

Comparative Bioactivity Evaluation of Chemically Characterized Essential Oils Obtained from Different Aerial Parts of Eucalyptus gunnii Hook. f. (Myrtaceae).

Essential oils (EOs) obtained by hydro-distillation from different parts of twigs (EOT), leaves (EOL), and fruits (EOF) of Eucalyptus gunnii Hook. f. were screened for their chemical composition, insecticidal, repellence, and antibacterial properties. Based on GC and GC/MS analysis, 23 constituents were identified across the twigs, leaves, and fruits, with 23, 23, and 21 components, respectively. The primary significant class was oxygenated monoterpenes (82.2-95.5%). The main components were 1,8-cineole (65.6-86.1%), α-terpinyl acetate (2.5-7.6%), o-cymene (3.3-7.5%), and α-terpineol (3.3-3.5%). All three EOs exhibited moderate antibacterial activities. EOL was found to have higher antibacterial activity against all tested strains except Dickeya solani (CFBP 8199), for which EOT showed more potency. Globally, Dickeya solani (CFBP 8199) was the most sensitive (MIC ≤ 2 mg/mL), while the most resistant bacteria were Dickeya dadantii (CFBP 3855) and Pectobacterium carotovorum subsp. carotovorum (CFBP 5387). Fumigant, contact toxicity, and repellent bioassays showed different potential depending on plant extracts, particularly EOT and EOL as moderate repellents and EOT as a medium toxicant.

Effects of Melaleuca alternifolia Chell (Tea Tree) and Eucalyptus globulus Labill. Essential Oils on Antibiotic-Resistant Bacterial Biofilms.

In the present investigation, the anti-biofilm potential of two essential oils (EOs), Melaleuca alternifolia Chell (Tea-Tree) (TTO) and Eucalyptus globulus Labill. (EEO) was characterized and tested "in vitro" against both mature biofilms and biofilms in the process of formation, produced by strains belonging to three main categories of antibiotic resistant bacteria (ARB): Vancomycin-resistant enterococci (VRE), methicillin-resistant Staphylococcus aureus (MRSA) and broad-spectrum ß-lactamase-producing Escherichia coli (ESBL). The study was carried out in 96-well microtiter-plates using EOs alone, in association with each other and in combination with antibiotics against both single and multi-species biofilm. The study demonstrated the ability of TTO and EEO to counteract the ARB strains in sessile form, with promising results in particular against the biofilm in formation. Mature biofilm by ESBL E. coli was the most sensitive in the results from the quantification study of viable cells performed in multi-species biofilms. Lastly, in all tests, carried out using TTO/EEO associations and EOs/antibiotic combinations, the synergistic effect which emerged from the FIC-index has been confirmed, and both the reduction of biofilm in formation, and the removal of mature structure was obtained at very low concentrations, with values from 4 to >512-fold lower than the minimum inhibitory concentration (MIC) of the single compounds.

Effect of enzymatic treatment on Eucalyptus globulus vessels passivation.

Hardwood vessel elements generate problems in industrial uncoated wood-free printing paper operation, causing vessel picking and ink refusal. These problems are mitigated using mechanical refining at the cost of paper quality. Vessel enzymatic passivation, altering its adhesion to the fiber network and reducing its hydrophobicity is a way of improving paper quality. The object of this paper is to study how the enzymatic treatment by xylanase and by an enzymatic cocktail containing cellulases and laccases affect elemental chlorine free bleached Eucalyptus globulus vessel and fiber porosities, bulk, and surface chemical compositions. Thermoporosimetry revealed the vessel structure to be more porous, surface analysis showed its lower O/C ratio and bulk chemistry analysis its higher hemicellulose content. Enzymes had different effects on porosity, bulk and surface composition of fibers and vessels, affecting vessel adhesion and hydrophobicity. Vessel picking count decreased 76% for papers containing vessels treated with xylanase and 94% for the papers with vessels treated with the enzymatic cocktail. Fiber sheet samples had lower water contact angle (54.1º) than vessels rich sheets (63.7º), that reduced with xylanase (62.1º) and cocktail (58.4º). It is proposed that differences in vessel and fiber porosity structures affect the enzymatic attacks, eventually causing vessel passivation.

In silico and in vitro anti-inflammatory study of phenolic compounds isolated from Eucalyptus maculata resin.

Plant resins are rich in bioactive compounds with high medicinal values. However, the chemistry and anti-inflammatory activity of the resins produced by trees of the genus Eucalyptus were scarcely investigated. The inflammatory targets cyclooxygenase-1 (COX-1), COX-2, TNF-, NF-B, and NO were significantly inhibited by the methanolic extract of Eucalyptus maculata kino resin (EME) and its CH2Cl2 soluble fraction (MCF). Sakuranetin (C1), (E)-cinnamic acid (C2), kaempferol 7- methyl ether (C3), 7-O-methyl aromadendrin (C4), and 1,6- dicinnamoyl-O-α-D-glucopyranoside (C5) were isolated from MCF. Three compounds (C1, C2, and C4) showed potent in vitro COX-1 inhibition, while C5 inhibited COX-2, TNF-α, NF-κB, and NO significantly. An in-silico study revealed that C5 had the highest binding affinity to the active site in COX-2 with binding energy score (S) of -14.85 kcal/mol, better than celecoxib (COX-2 inhibitor). In conclusion, 1,6-dicinnamoyl-O-α-D-glucopyranoside (C5) could be investigated further in the search for anti-inflammatory agents.

Membrane-processed honey samples for pollen characterization with health benefits.

Better processing techniques must be utilized widely due to the rising demand for honey. The most common honey processing techniques are applied to melissopalynomorphs to check the quality and quantity of valuable honey using microporous ultrafiltration membranes. It is essential to have the ability to selectively filter out sugars from honey using ultrafiltration. This study authenticated 24 honey samples using membrane reactors ultrafiltration protocol to describe the pollen spectrum of dominant vegetation. The purpose of this study was also to explore nutritional benefits as well as the active phytochemical constituents of honey samples. Honey samples were collected and labeled Acacia, Eucalyptus, and Ziziphus species based on plant resources provided by local beekeepers. A variety of honeybee flora was collected around the apiaries between 2020 and 2021. Honey analysis revealed that the pollen extraction of 24 bee foraging species belonging to 14 families. The honey membrane technology verified the identities of honey and nectar sources. Also, pollen identified using honey ultrafiltration membranes revealed dominant resources: Acacia spp. (69%), Eucalyptus spp. (52%) and Ziziphus spp. Honey filtration using a membrane technology classified 14 samples as unifloral, represented by six dominant pollen types. The absolute pollen count in the honey sample revealed that 58.33% (n = 14) belong to Maurizio's class I. Scanning ultrasculpturing showed diverse exine patterns: reticulate, psilate, scabrate-verrucate, scabrate-gemmate, granulate, perforate, microechinate, microreticulate, and regulate to fossulate for correct identification of honey pollen types. Honey ultrafiltration should be utilized to validate the botanical sources of honey and trace their biogeographic authenticity. Thus, it is imperative to look at the alternative useful method to identify the botanical origin of filtered honey. It is critical to separate honey from adulteration by a standardized protocol. Membrane technology has yielded significant outcomes in the purification of honey.

Aloe Vera coated Dextran Sulfate/Chitosan nanoparticles (Aloe Vera @ DS/CS) encapsulating Eucalyptus essential oil with antibacterial potent property.

The goal of this work is to encapsulate Eucalyptus staigeriana essential oil in biopolymer matrices, to optimize the biological effects and the antibacterial properties of this oil. In this study, Eucalyptus extract was encapsulated in Aloe Vera coated Dextran Sulfate/Chitosan nanoparticles to form a hydrogel with potent properties. In this study, Eucalyptus extract was loaded on to Aloe Vera coated Dextran Sulphate/Chitosan nanoparticles to obtain a nano-hydrogel with potent properties. The characterization of nanoparticles was evaluated using transmission and scanning electron microscopes, dynamic light scattering, Fourier transform infrared spectroscopy, differential scanning calorimetry and antibacterial activity. The E. staigeriana release profile from the prepared nanoparticles was studied in vitro at a pH of 7.4. The results showed that this nano-carrier controls Eucalyptus release. Aloe Vera coated Dextran Sulfate/Chitosan nanoparticles encapsulated with E. staigeriana inhibited the bacteria by 47.27%. These investigations concluded that E. staigeriana loaded Aloe Vera coated Dextran Sulfate/Chitosan hydrogel could be used as a powerful dressing material to accelerate wound healing.

Eucarbwenstols A-H, eight novel compounds from Eucalyptus robusta prevents MPC-5 injury via ROS modulation and regulation of mitochondrial membrane potential.

BACKGROUND: The damage of podocytes is a primary hallmark of lupus nephritis (LN). Therefore, finding an effective way to inhibit the podocyte injury is important for improving the survival and development of patients with LN. Eucalyptus robusta exhibits anti-inflammatory properties. However, whether Formyl phloroglucinol meroterpenoids (FPMs), which are specialized metabolites of the genus Eucalyptus, is an anti-inflammatory active ingredient of E. robusta remains to be determined. PURPOSE: This study asimed to identify novel FPMs from E. robusta and investigated their anti-inflammatory effects. METHODS: Various separation methods were used to isolate and identify the compounds in the PE extract of E. robusta. The structures of the isolates were determined using 1D/2D NMR data and electron circular dichroism (ECD) calculations. The level of mitochondrial reactive oxygen species (ROS) level and mitochondrial membrane potential (MMP) of the podocyte cell line, MPC-5, were assessed using a multifunctional microplate reader combined with flow cytometry and fluorescence microscopy. RESULTS: Eight novel FPMs (1-8, Eucarbwenstols A-H, Fig. 1) and 15 known FPMs (9-23) were purified from the PE extract of E. robusta. It is noteworthy that compound 1 possesses an unprecedented FPM carbon skeleton. Among these compounds, compounds 1, 2, 4 and 5 showed the most promising potential for protecting MPC-5 cells because pretreatment with pro-inflammatory cytokines TGF-ß, IFN-α and IL-6 decreased ROS production and ameliorated the mitochondrial state. CONCLUSIONS: Our research contributes to the characterization of E. robusta constituents and highlights the anti-inflammatory effects of FPMs.

Singular and Combined Effects of Essential Oil and Honey of Eucalyptus Globulus on Anti-Inflammatory, Antioxidant, Dermatoprotective, and Antimicrobial Properties: In Vitro and In Vivo Findings.

Eucalyptus globulus is a plant widely used by the world population, including Morocco, in the treatment of several pathologies. The aim of this work is to evaluate the antioxidant, anti-inflammatory, dermatoprotective, and antimicrobial effects of essential oil and honey from E. globulus, as well as their combination. Chemical composition was determined by GC-MS analysis. The antioxidant activity was evaluated by three tests, namely, DPPH, reducing power, and the ß-carotene/linoleic acid assay. The anti-inflammatory activity was investigated in vitro (5-lipoxygenase inhibition) and in vivo (carrageenan-induced paw edema model), while the dermatoprotective activity was tested in vitro (tyrosinase inhibition). Moreover, the antibacterial activity was assessed using agar well diffusion and microdilution methods. The results showed that eucalyptol presents the main compound of the essential oil of E. globulus (90.14%). The mixture of essential oil with honey showed the best antioxidant effects for all the tests used (0.07 < IC50 < 0.19 mg/mL), while the essential oil was the most active against tyrosinase (IC50 = 38.21 ± 0.13 µg/mL) and 5-lipoxygenase (IC50 = 0.88 ± 0.01 µg/mL), which corroborated the in vivo test. Additionally, the essential oil showed the best bactericidal effects against all strains tested, with inhibition diameter values ranging from 12.8 to 21.6 mm. The findings of this work showed that the combination of the essential oil with honey showed important results in terms of biological activity, but the determination of the underlying mechanisms of action remains a major prospect to be determined.

Quality assessment of Portuguese monofloral honeys. Physicochemical parameters as tools in botanical source differentiation.

The quality evaluation and physicochemical parameters assessment of Portuguese monofloral honeys were performed. Fifty-one monofloral honeys were collected from several regions from mainland Portugal, and from the Azores islands, producer labelled as carob tree (n = 5), chestnut (n = 2), eucalyptus (n = 5), bell heather (n = 6), incense (n = 4), lavender (n = 8), orange (n = 9), rape (n = 2), raspberry (n = 2), rosemary (n = 1), sunflower (n = 3), and strawberry tree (n = 4). Pollen analysis and microbiological safety were evaluated, and the parameters such as colour index, moisture content, electrical conductivity, hydroxymethylfurfural, pH, free and total acidity, diastase activity, proline, and sugar profile were assessed for physicochemical characterization, in all 51 monofloral honeys. After melissopalynological examination, the honeys were either confirmed as monofloral, or classified as multifloral with predominance of a specific pollen type or multifloral. Microbiological analysis showed that honeys were safe for human consumption. Pairwise comparisons of physicochemical parameters, using only honey types with n ≥ 3, revealed significant differences between honey types. Despite some homogeneity in sugar profile among honeys, eucalyptus honey was significantly different in glucose, maltose and maltulose content compared to incense, orange and sunflower honeys, and also exhibited a higher isomaltose amount compared to all analyzed honeys. Electrical conductivity, colour index, free and total acidity, and diastase activity showed significant differences between the analyzed honeys, indicating that these parameters may provide an additional tool in monofloral honey identification.

Highly selective separation of eucalyptus hemicellulose by salicylic acid treatment with both aromatic and hydroxy acids.

Aromatic and hydroxyl acid treatments demonstrate their respective characteristics for the separation of lignocellulosic biomass. In this study, the effect of salicylic acid (SA-A) treatment on the separation of eucalyptus components with both aromatic and hydroxyl acid properties was analyzed. The optimal conditions were SA-A concentration 9.0%, reaction temperature 140 °C and time 75 min. The separation yield of xylose was 85.93%. The separation of cellulose and lignin was inhibited by SA-A treatment in contrast to the separation by glycolic acid and p-toluenesulfonic acid treatment. Moreover, SA-A treatment resulted in a larger fiber crystallinity index and higher thermal stability. The SA-A-treated samples contained lignin that was rich in ß-O-4 and hydroxyl groups. The degradation and condensation of lignin was inhibited. The selectivity of aromatic acids for separating hemicellulose and protecting the lignin structure using hydroxy acids was demonstrated. Thus, new and efficient organic acid treatments can be developed.

Structural Diversity of Complex Phloroglucinol Derivatives from Eucalyptus Species.

Several species of the genus Eucalyptus are used in many traditional medicine systems for the treatment of respiratory tract infections, colds, flu, sore throats, and bronchitis. The genus Eucalyptus (Myrtaceae) is a well-known natural source of bioactive phloroglucinols. These polyphenolic compounds bear an aromatic phenyl ring with three hydroxy groups (1,3,5-trihydroxybenzene) which have been exhibiting a variety of biological activities such as antimicrobial, anticancer, anti-allergic, anti-inflammatory, and antioxidant activities. This review summarizes the literature published from 1997 until the end of 2021 and addresses the structure diversity of phloroglucinols isolated from Eucalyptus species and their biological activities. Phloroglucinol-terpene adducts are the main class of compounds that have been reported in this genus.

Phloroglucinol-meroterpenoids from the leaves of Eucalyptus camaldulensis Dehnh.

Fourteen undescribed phloroglucinol-meroterpenoids, namely eucalypcamals A-N, were isolated from a CH2Cl2 extract of the leaves of Eucalyptus camaldulensis Dehnh. In addition, from the same extract, twelve known phloroglucinols, three known flavonoids, and four known phenolic compounds were also isolated. The structures of the undescribed compounds were analyzed by 1D and 2D nuclear magnetic resonance (NMR) spectroscopy, and high resolution electrospray ionization mass spectrometry (HRESIMS). The assignments of the absolute configurations were performed by comparing the experimental electronic circular dichroism (ECD) data with the calculated values. Eucalyprobusal E was found to be cytotoxic against HCT116, Jurkat, and MDA-MB-231 cell lines with IC50 values of 17.6, 9.44, and 17.9 µM, respectively. Eucalrobusone F exhibited antibacterial activity against methicillin-resistant S. aureus (MRSA) and S. aureus with minimum inhibitory concentration/minimum bactericidal concentration (MIC/MBC) values of 4/4 µg/mL while euglobal Ia1 showed antifungal activity with MIC/MFC values of 16/16 µg/mL.