Search Results (19)

This study investigates the impact of rootstock selection on the essential oil (EO) composition of clementine mandarin (Citrus clementina Hort. ex Tan.) var. SRA 63 cultivated in southern Greece. EOs were extracted from the peel and leaves of trees grafted on four commonly used rootstocks: Cleopatra mandarin, sour orange, Troyer citrange, and Swingle citrumelo. The GC-MS analysis revealed significant qualitative and quantitative differences in EO profiles across the different rootstock combinations. In peel EOs, limonene was the dominant compound, particularly in trees grafted onto Cleopatra mandarin and Swingle citrumelo, while Troyer citrange favored a more diverse chemical profile rich in oxygenated monoterpenes, sesquiterpenes, and aldehydes. Leaf EOs were characterized by high levels of sabinene, linalool, and limonene, with Swingle citrumelo promoting sabinene production and Troyer citrange enhancing limonene content and sesquiterpene diversity. Sour orange showed an intermediate effect, increasing both compound diversity and abundance. These results underscore the critical role played by rootstock in modulating the biosynthesis of volatile compounds, likely through physiological and molecular interactions with the scion. These findings offer valuable insights into optimizing EO yield and quality in citriculture and support the broader goal of valorizing Citrus by-products through targeted agricultural practices. This research contributes to the implementation of targeted agricultural practices (rootstock choice) for the development of high-value Citrus-based products with specific quality traits. Full article

Knowledge on the spatiotemporal patterns of surface energy balance parameters is crucial for understanding climate system processes. To this end, the assimilation of Earth Observation data with land biosphere models has shown promising results, but they are still hampered by several limitations related to the spatiotemporal resolution of EO sensors and cloud contamination. With the recent developments on Unmanned Aerial Vehicles (UAVs), there is a great opportunity to overcome these challenges and gain knowledge of surface energy balance parameters at unprecedented resolutions. The present study examines, for the first time, the ability of an inversion-modeling scheme, the so-called “analytical triangle” method, to retrieve estimates of surface energy fluxes and soil surface moisture (SSM) at high spatial resolution using UAV data. A further aim of our study was to examine the representativeness of the SSM estimates for the SM measurements taken at different depths. The selected experimental site is an agricultural site of citrus trees located near the city of Palermo on 30 July 2019. The results of comparisons showed that the sensible and latent heat fluxes from UAV were consistent with those measured from the ground, with absolute differences in comparison to ground measurements being 5.00 Wm⁻² for the latent heat (LE) flux and 65.02 Wm⁻² for H flux, whereas for the daytime fluxes H/Rn and LE/Rn were 0.161 and 0.012, respectively. When comparing analytical triangle SSM estimates with SM measurements made at different depths, it was found that there was a gradual increase in underestimation with increasing measurement depth. All in all, this study’s results provide a credible demonstration of the significant potential of the technique investigated herein as a cost-effective and rapid solution for estimating key parameters characterizing land surface processes. As those parameters are required by a wide range of disciplines and applications, utilization of the investigated technique in research and practical applications is expected to be seen in the future. Full article

Citron (Citrus medica L. cv. Liscia-diamante), cultivated in the “Riviera dei Cedri” (southern Italy), is mainly utilized in the production of candied fruit and essential oils (EOs). Up to now, no information regarding the effect of storage temperatures on citron has been reported. Here, citron samples, after harvesting, were stored at different temperatures (5, 10 and 20 °C at 70% relative humidity) for two weeks, and the main postharvest quality parameters were evaluated. Moreover, EOs extracted from the stored samples were chemically characterized to reveal changes in the volatiles profile and antimicrobial activity. The EOs presented monoterpene hydrocarbons (87.1 to 96.3% of the total oil profile) as the most abundant compounds, followed by oxygenated metabolites ranging from 9.7 to 3.1% of the total pattern. Postharvest quality traits showed a good retention of green peel color during storage at 5 °C, while EOs from samples stored for 7 and 14 days at 10 and 20 °C, respectively, showed the highest antimicrobial activity against most assayed strains. The results indicated storage at 10 °C for 7 days as the most suitable for the preservation of the postharvest quality of the fruit and the antimicrobial activity of the extracted EOs. Full article

The aroma of citrus is among the most appealing natural flavors. ‘Huyou’ (HY) is a hybrid citrus with a unique flavor compared to grapefruit (GF), but few studies have analyzed its characteristic flavor comprehensively. In this study, we extract six essential oils (EOs) from HY and GF peels by cold pressing (CP) and microwave-assisted hydrodistillation (MADH) and spinning cone column (SCC). Further, the flavor of six EOs was investigated by using flavoromics analysis, including e-nose, GC-MS and GC-O combined with chemometric approaches. The results showed that CP EOs exhibited a stronger citrus characteristic flavor, while MADH and SCC EOs contained more diverse volatiles. A total of 23 key odorants were identified in the GC-O-MS analysis, 12 of which were specific to HY. The flavor wheel and partial least squares regression (PLSR) revealed that floral, sweet and fruity odors were positively correlated with linalool, α-terpineol and geraniol, while fatty, green and woody odors with germacrene D, germacrene B and nootkatone. Additionally, based on orthogonal partial least squares discriminant analysis (OPLS-DA), six aroma-active compounds were screened as aroma markers to distinguish HY from GF; i.e., γ-terpinene, D-limonene, germacrene D, nootkatone, germacrene B and terpinolene. The extraction methods and citrus varieties both impact the flavor characterization of citrus EOs, and our study provides guidance on the extraction and application for citrus EOs. Full article

Staphylococcus aureus is a major cause of subclinical mastitis in dairy cows, and its development of antibiotic resistance has limited treatment efficacy. Essential oils (EOs) are natural products with a wide range of antimicrobial properties that could be used to treat bovine mastitis. This study aims to investigate the antimicrobial activity of EOs against S. aureus isolated from subclinical bovine mastitis cases in the State of São Paulo—Brazil. A total of 14 S. aureus isolates were selected, based on the presence of biofilm-forming genes (icaA, icaD, and bap), and were cultured to a final concentration of 10³ CFU.mL⁻¹ for the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) analysis of five EOs (Citrus aurantium bergamia—bergamot, Copaifera reticulata—copaiba, Foeniculum vulgare—fennel, Zingiber officinale—ginger, and Ocimum basilicum—basil). The chemical compositions of the EOs were characterized using gas chromatography coupled with a mass-selective detector (GC/MSD). Basil and bergamot EOs exhibited the highest antimicrobial activity against S. aureus strains, with mean MIC/MBC values of 1.561 ± 0.223/2.806 ± 0.255 mg.mL⁻¹ and 2.782 ± 0.228/4.396 ± 0.198 mg.mL⁻¹, respectively. The primary compounds in basil EO were methyl-chavicol, linalool, and α-humulene, while bergamot EO predominantly contained linalyl acetate, limonene, and linalool. This research highlights the potential of basil and bergamot EOs as natural antimicrobial agents for treating bovine mastitis caused by S. aureus, offering a potential alternative to traditional antibiotics and contributing to animal welfare and public health. In addition, it emphasizes the need for further studies to validate the long-term effects, optimal dosages, and application methods. Full article

Citrus lumia Risso and Poit. ‘Pyriformis’ are horticultural varieties of Citrus lumia Risso. The fruit is very fragrant and pear-shaped, with a bitter juice, a floral flavor, and a very thick rind. The flavedo shows enlarged (0.74 × 1.16 mm), spherical and ellipsoidal secretory cavities containing the essential oil (EO), visible using light microscopy, and more evident using scanning electron microscopy. The GC-FID and GC-MS analyses of the EO showed a phytochemical profile characterized by the predominance of D-limonene (93.67%). The EO showed interesting antioxidant and anti-inflammatory activities (IC₅₀ 0.07–2.06 mg/mL), as evaluated by the in vitro cell-free enzymatic and non-enzymatic assays. To evaluate the effect on the neuronal functional activity, the embryonic cortical neuronal networks grown on multi-electrode array chips were exposed to non-cytotoxic concentrations of the EO (5–200 µg/mL). The spontaneous neuronal activity was recorded and the mean firing rate, mean burst rate, percentage of spikes in a burst, mean burst durations and inter-spike intervals within a burst parameter were calculated. The EO induced strong and concentration-dependent neuroinhibitory effects, with IC₅₀ ranging between 11.4–31.1 µg/mL. Furthermore, it showed an acetylcholinesterase inhibitory activity (IC₅₀ 0.19 mg/mL), which is promising for controlling some of the key symptoms of neurodegenerative diseases such as memory and cognitive concerns. Full article

Food waste is one of the main topics of various scientific studies of the last decade. In this regard, this work analyzed an essential oil (EO) extracted from the flavedo of Citrus aurantium ‘Crispifolia’ fruit. The analysis, performed by GC-MS, showed a chemically variegated chromatogram characterized by the presence of limonene (33.35%), but also by oxygenated monoterpenes such as β-linalool (7.69%), α-terpineol (7.06%), and geranyl acetate (10.12%). EO from the external part of the C. aurantium peel had several properties, including excellent antimicrobial and good antibiofilm activities. It also showed antioxidant activity in vitro and decreased the amount of cellular ROS, thus stimulating the catalytic activity of crucial enzymes involved in mitigating oxidative stress. Full article

Citrus is one of the main fruit crops cultivated in tropical and subtropical regions worldwide. Approximately half (40–47%) of the fruit mass is inedible and discarded as waste after processing, which causes pollution to the environment. Essential oils (EOs) are aromatic compounds found in significant quantities in oil sacs or oil glands present in the leaves, flowers, and fruit peels (mainly the flavedo part). Citrus EO is a complex mixture of ~400 compounds and has been found to be useful in aromatic infusions for personal health care, perfumes, pharmaceuticals, color enhancers in foods and beverages, and aromatherapy. The citrus EOs possess a pleasant scent, and impart relaxing, calming, mood-uplifting, and cheer-enhancing effects. In aromatherapy, it is applied either in message oils or in diffusion sprays for homes and vehicle sittings. The diffusion creates a fresh feeling and enhances relaxation from stress and anxiety and helps uplifting mood and boosting emotional and physical energy. This review presents a comprehensive outlook on the composition, properties, characterization, and mechanism of action of the citrus EOs in various health-related issues, with a focus on its antioxidant properties. Full article

Influenza viruses are transmitted from human to human via airborne droplets and can be transferred through contaminated environmental surfaces. Some works have demonstrated the efficacy of essential oils (EOs) as antimicrobial and antiviral agents, but most of them examined the liquid phases, which are generally toxic for oral applications. In our study, we describe the antiviral activity of Citrus bergamia, Melaleuca alternifolia, Illicium verum and Eucalyptus globulus vapor EOs against influenza virus type A. In the vapor phase, C. bergamia and M. alternifolia strongly reduced viral cytopathic effect without exerting any cytotoxicity. The E. globulus vapor EO reduced viral infection by 78% with no cytotoxicity, while I. verum was not effective. Furthermore, we characterized the EOs and their vapor phase by the head-space gas chromatography–mass spectrometry technique, observing that the major component found in each liquid EO is the same one of the corresponding vapor phases, with the exception of M. alternifolia. To deepen the mechanism of action, the morphological integrity of virus particles was checked by negative staining transmission electron microscopy, showing that they interfere with the lipid bilayer of the viral envelope, leading to the decomposition of membranes. We speculated that the most abundant components of the vapor EOs might directly interfere with influenza virus envelope structures or mask viral structures important for early steps of viral infection. Full article

The present work aimed to chemically characterize and evaluate the antiradical power and biological effects of Citrus medica var. sarcodactylus essential oil (EO) and hydrolate (Hy) from exocarp as well as methanol extracts, from both exocarp and mesocarp (EEX and MEX). The whole fresh fruit was also investigated by SPME-GC/MS to describe its volatile composition. EO and Hy were analyzed by GC/MS and HS-GC/MS techniques, respectively. Limonene and γ-terpinene were found to be the most abundant compounds both in the fresh parts of the fruit and in the EO, while α-terpineol and terpinen-4-ol were in the Hy. The extracts were also rich in furan and coumarin derivatives. A good antiradical activity of all samples except Hy was detected both against ABTS·+ than DPPH·, removed up to about 50%. The antibacterial activity against Bacillus cereus and Escherichia coli was evaluated by microwell dilution method to determine MIC and MBC values. EEX and MEX showed efficacy at very high concentrations against both tested bacteria. The MIC value of EO against B. cereus was 0.5% v/v, while Hy was not able to inhibit the bacterial growth at the tested concentrations. Cytotoxicity investigated on the HL60 leukemia cell line by MTT assay provided an EC₅₀ of 1.24% v/v for EO. Interesting activity of Hy was also observed. Full article

In this work, seven Citrus aurantium essential oils (EOs) derived from flavedo of cultivars ‘Canaliculata’, ‘Consolei’, ‘Crispifolia’, ‘Fasciata’, ‘Foetifera’, ‘Listata’, and ‘Bizzaria’ were investigated. EOs were also combined in 1:1 (v/v) ratio to identify possible synergism or antagonism of actions. GC-MS analysis was done to investigate Eos’ phytochemical profiles. The antioxidant activity was studied by using a multi-target approach based on FRAP, DPPH, ABTS, and β-carotene bleaching tests. A great difference was observed in EOs’ phytochemical profiles. d-limonene (33.35–89.17%) was the main monoterpene hydrocarbon, and α-Pinene, β-myrcene, and β-linalool were identified in almost all samples. Among EOs, only C3 showed high quantitative and qualitative variability in its chemical composition. The chemical diversity of EOs was also demonstrated by PCA and HCA statistical analysis. Samples C2, C4, C5, C6, and C7 were statistically similar to each other, while C1 and C3 were characterized as having a different amount of other compounds and oxygenated monoterpenes, respectively, with respect to the other EOs mentioned. The global antioxidant score (GAS) revealed that among the tested EOs, C. aurantium ‘Fasciata’ EO had the highest antioxidant potential, with a GAS value of −0.47, whereas among combinations, the EO obtained by mixing ‘Canaliculata’ + ‘Bizzaria’ was the most active. Comparison by theoretical and real data on inhibitory concentration (IC₅₀) and FRAP values did not reveal any significant effect of synergism or antagonism of actions to be valid in all biological applied tests. These findings, considered together, represent an important starting point to understand which compounds are responsible for the activities and their future possible industrial application. Full article

After harvest, numerous plant pathogenic fungi can infect fresh fruits during transit and storage. Although synthetic fungicides are often used to manage postharvest fruit diseases, their application may lead to problems such as the development of fungicide resistance and residues on fruits. In the present study, the antifungal potential of nine commercial essential oils (EOs) extracted from Eucalyptus radiata ssp. radiata, Mentha pulegium, Rosmarinus officinalis, Origanum compactum, Lavandula angustifolia, Syzygium aromaticum, Thymus vulgaris, Citrus aurantium, and Citrus sinensis were tested against the apple brown rot fungi Monilinia laxa and Monilinia fructigena at different concentrations in vitro (against mycelial growth and spore germination) and in vivo (on detached apple fruit and in semi-commercial postharvest conditions). In addition, fruit quality parameters were evaluated and the composition of the EOs was characterized by Fourier transform infrared (FT-IR) spectroscopy. In vitro results showed significant antifungal activity of all tested EOs on both fungal species. EOs from S. aromaticum were the most effective, whereby inhibition percentages ranged from 64.0 to 94.7% against M. laxa and from 63.9 to 94.4% against M. fructigena for the concentrations 12.5 and 100 µL/mL, respectively, with an EC50 of 6.74 µL/mL for M. laxa and 10.1 µL/mL for M. fructigena. The higher concentrations tested of S. aromaticum, T. vulgaris, C. aurantium, and C. sinensis EOs significantly reduced spore germination, brown rot incidence, and lesion diameter. Evaluation of the treatments during storage for 20 days at 4 °C on apple fruit quality parameters demonstrated the preservation of the fruit quality characteristics studied (weight loss, total soluble solids, titratable acidity, firmness, and maturity index). FT-IR spectra obtained from all tested EO samples presented characteristic peaks and a high diversity of functional groups such as O–H groups, C–H bonds, and C–C stretching. The EOs examined here may have the potential for controlling postharvest fungal diseases of fruit such as brown rot. Full article

Due to the high volume of peel produced, Citrus by-product processing could be a significant source of phenolic compounds, in addition to essential oil. Citrus fruit residues, which are usually dumped as waste in the environment, could be used as a source of nutraceuticals. Citrus aurantium (L), also known as sour or bitter orange, is a member of the Rutaceae family and is the result of interspecific hybridization between Citrus reticulata and Citrus maxima. The purpose of this study is to chemically and biologically evaluate the peel of C. aurantium, which is considered a solid waste destined for abandonment. To achieve more complete extraction of the phytochemicals, we used a sequential extraction process with Soxhlet using the increasing polarity of solvents (i.e., cyclohexane, chloroform, ethyl acetate, acetone, and ethanol–water mixture). Essential oil (EO) from the Citrus peel, which was present at 1.12%, was also prepared by hydrodistillation for comparison. Various phytochemical assays were used to determine the qualitative chemical composition, which was subsequently characterized using GC-MS and HPLC-DAD. The inhibitory effects of C. aurantium peel extract on two enzymes, intestinal α-glucosidase and pancreatic α-amylase, were measured in vitro to determine their potential hypoglycemic and antidiabetic actions. Each extract had a significantly different phytochemical composition. According to GC-MS analyses, which allow the identification of 19 compounds, d-limonene is the most abundant compound in both EO and cyclohexane extract, at 35.17% and 36.15% (w/w). This comparison with hydrodistillation shows the value of the sequential process in extracting this valuable terpene in large quantities while also allowing for the subsequent extraction of other bioactive substances. On the contrary, linoleic acid is abundant (54.35% (w/w)) in ethyl acetate extract (EAE) with a lower amount of d-limonene. HPLC-DAD analysis allows the identification of 11 phytochemicals, with naringenin being the most abundant flavanone, detected in acetone extract (ACE) (23.94% (w/w)), ethanol–water extract mixture (EWE) (28.71% (w/w)), and chloroform extract (CFE) (30.20% (w/w)). Several extracts significantly inhibited α-amylase and/or α-glycosidase in vitro. At a dose of 332 g/mL, ACE, CFE, and EWE inhibited the two enzymes by approximately 98%. There were strong significant correlations between naringenin and α-glucosidase inhibition and between gallic acid and α-amylase inhibition. Molecular docking experiments further verified this. Finally, oral administration of C. aurantium extracts at a dose of 2000 mg/kg did not cause any effect on mice mortality or signs of acute toxicity, indicating that it is non-toxic at these doses. These findings suggest that C. aurantium peels could be a valuable by-product by providing a rich source of non-toxic phytoconstituents, particularly those with potential antidiabetic action that needs to be confirmed in vivo. Full article

Chemical characterization of clementine varieties (Citrus clementina Hort. ex Tan.) essential oils (EO) can lead to variety identification and valorization of their potential use in food and aroma industries. The goal of this study was the chemometric discrimination between two very closely related and morphologically identical clementine varieties, Clemenules (NL) and Clemenpons (PO), based on their rind EO, to identify the differential volatile organic compounds (VOCs) and to determine their antioxidant capacity. EO rind volatile profile was determined by gas chromatography coupled to mass spectrometry in Citrus fruit at different ripening stages grown two independent years in two different locations. Untargeted metabolomics and multivariate data analysis showed an evolution of EO volatile profiles markedly parallel in both varieties. Although EO qualitative composition was identical in both varieties, PLS-DA allowed the identification of characteristic VOCs, quantitatively discriminating them along all the ripening process. PO showed higher accumulation of several mono- and sesquiterpene compounds such as trans-carveol, while NL showed higher levels of aldehyde and alcohol non-terpenoids like dodecanal. Both varieties evinced identical EO antioxidant activities, indicating a similar value for food preservation. Hence, untargeted metabolomics approach based on rind EO volatiles was revealed as a powerful technique able to differentiate between morphologically undistinguishable Citrus varieties. Full article

Essential oils (EOs) can be a large source of new food-safe and healthy nematicidal products, due to their strong activity on crop pathogens and pests, including phytoparasitic nematodes, as well as to their low environmental persistence. This review summarizes the results from our 10-year studies on chemical features and nematicidal properties of 16 EOs with different botanical origins and compositions, i.e., the EOs from Artemisia herba-alba Asso (Asteraceae), Cinnamomum camphora (L.) J. Presl. and Cinnamomum verum J. Presl. (Lauraceae), Citrus aurantium L., Cinnamomum. sinensis L. Osbeck and Ruta graveolens L. (Rutaceae), Eucalyptus citriodora Hook, Eucalyptus globulus Labill. and Syzygium aromaticum (L.) Marry et Perry (Myrtaceae), Mentha piperita L., Monarda didyma L., Monarda. fistulosa L., Rosmarinus officinalis L. and Thymus satureioides Cosson (Lamiaceae), Pelargonium asperum Ehrh ex Willd (Geraniaceae) and Schinus molle L. (Anacardiaceae). All these EOs were chemically characterized and tested in vitro and/or in vivo for their activity against the phytoparasitic species Meloidogyne incognita Kofoid et White (Chitw.), Pratylenchus vulnus Allen et Jensen and Xiphinema index Thorne et Allen. Toxicity bioassays were conducted by exposing 2nd stage juveniles (J2) of M. incognita, mixed-age specimens of P. vulnus and adult females of X. index to 2–100 μg mL⁻¹ concentrations of EOs or EO’s major constituents for 4–96 h and checking mortality effect after a further 24–72 h permanence in water. Egg hatchability bioassays consisted in exposing (24–48 h) M. incognita egg masses to 500–1000 mg mL⁻¹ EO solutions followed by a 5-week hatching test in water. The in vivo experiments were undertaken in sandy soil strongly infested by M. incognita and treated with different doses of EOs, applied either in water solution or by fumigation. The effects of the treatments on nematode infestation on tomato and in soil were checked at the end of each experiment. Structure-activity relationships, as suggested by the different chemical compositions of tested EOs, were also highlighted. In agreement with literature data, our studies indicated that most of the tested EOs are highly suitable for the formulation of new safe nematicides, though still retarded by the lack of efficient stabilization processes and standardized EOs’ components and extraction techniques. Full article