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The aim of the present study is to investigate the chemical profile, antioxidant activity, carbohydrate-hydrolysing enzyme inhibition, and hypolipidemic effect of essential oils (EOs) extracted from Sicilian Citrus maxima (pomelo) flavedo. Using gas-chromatography-mass spectrometry analysis (GC-MS) we analysed the Eos of five cultivars of C. maxima, namely, 'Chadock', 'Maxima', 'Pyriformis', 'Terracciani', and 'Todarii', and their blends. The antioxidant activity was performed by using a multi-target approach using 2,2'-Azino-Bis-3-Ethylbenzothiazoline-6-Sulfonic acid (ABTS), 2,2-Diphenyl-1-picrylhydrazyl (DPPH), ferric reducing ability power (FRAP), and β-carotene bleaching tests. The α-amylase, α-glucosidase, and lipase-inhibitory activities were also assessed. GC-MS analyses revealed D-limonene as the main monoterpene hydrocarbon in all cultivars, albeit with different percentages in the range of 21.72-71.13%. A good content of oxygenated monoterpenes was detected for all cultivars, especially for 'Todarii'. The analysis of the principal components (PCA), and related clusters (HCA), was performed to find chemo-diversity among the analysed samples. EOs from 'Chadock' and 'Maxima' were statistically similar to each other, and they differed from P3 in the smaller amount of sesquiterpene hydrocarbons, while the oils from 'Terracciani' and 'Todarii' were found to be chemically and statistically different. 'Chadock' EO was the most active to scavenge radicals (IC 50 values of 22.24 and 27.23 µg/mL in ABTS and DPPH tests, respectively). 'Terracciani' EO was the most active against both lipase and α-amylase, whereas the blends obtained by the combination (1:1 v / v ) of C. maxima 'Maxima' + 'Todarii' were the most active against α-glucosidase. Generally, the blends did not exert a unique behaviour in potentiating or reducing the bioactivity of the pomelo EOs.

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 (IC 50 ) 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.

Plants are a rich source of natural bioactive compounds with a wide range of applications in the food and pharmaceutical industries. Citrus × clementina leaves extracts and essential oils may be a potential candidate for formulation of products characterized by hypoglycaemic, antioxidant and anti-browning properties. C. × clementina leaves collected in three different areas in Calabria (South Italy) were extracted by Soxhlet apparatus, maceration, Ultrasound assisted maceration, and hydrodistillation. Hesperidin, tangeritin, and sinensetin were identified by HPLC-DAD analysis as dominant constituents of the extracts. The absence of coumarins and furanocoumarins was demonstrated. GC-MS analyses of essential oils evidenced the presence of sabinene, linalool, and (E)-β-ocimene as main compounds. Based on RACI and GAS values calculated by the integration of data obtained by DPPH, ABTS, FRAP and β-carotene bleaching methods, hydroalcoholic extract obtained by Ultrasound assisted maceration of the leaves collected in Corigliano Calabro showed the highest antioxidant activity. Ultrasound assisted hydroalcoholic extract of Cetraro leaves revealed the highest α-amylase inhibitory activity (IC 50 of 64.37 μg/ml). Promising results of C. × clementina extracts as tyrosinase inhibitors were also obtained. To evaluate the relationship between identified compounds and bioactivity PCA was performed. Taking into account results obtained by this study, C. × clementina leaves that were considered Citrus-by-products could be utilized for formulation of food additives, nutraceuticals and functional foods., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

This study aimed to investigate the antidiabetic, antilipidaemic and antioxidant activities of Citrus medica cv Diamante (Rutaceae) hydroalcoholic (CD) peel extract in Zucker diabetic fatty (ZDF) rats. The ability of CD to protect against oxidative stress was investigated by using different in vitro assays and in vivo by using the reactive oxygen metabolites-derived compounds (d-ROMs) test and the biological antioxidant potential test (BAP). Two different doses of CD extract (300 and 600 mg/kg/die) were administered at ZDF rats for 4 weeks. CD reduced cholesterol and triglycerides levels. A dose-dependent effect on body weight and serum glucose levels was observed. A decrease of d-ROMs and an increase of BAP were recorded by using the dose of 600 mg/kg. The extract inhibited lipid peroxidation (IC50 value of 0.23 mg/ml). These findings suggest as an efficient phytotherapeutic approach in combating hyperlipidaemic and hyperglycaemic disorders.

Citrus × limon cv. Femminello Comune (Rutaceae) from Rocca Imperiale (Italy), one of the six Protected Geographical Indication (PGI) Italian lemon crops, has been recently received renewed interest. In this work, fresh and dried peels and leaves were extracted by hydrodistillation, supercritical fluid extraction (SFE), and Soxhlet apparatus. Chemical profile was assessed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). Except for leaves extracts obtained by Soxhlet apparatus, the monoterpene hydrocarbons fraction dominated. Limonene, γ-terpinene, and β-pinene were the main identified compounds. The antioxidant activity was investigated using different in vitro assays namely 2,2-diphenyl-1-picrylhydrazyl (DPPH), ABTS, ferric reducing ability power (FRAP), and β-carotene bleaching test. In DPPH test, the essential oil obtained by hydrodistillation of fresh peel exhibited the highest activity (IC50 of 1.17 mg/ml). Leaves extracted by SFE showed a good activity in both DPPH and β-carotene bleaching test with IC50 values of 2.20 and 6.66 mg/ml, respectively. Monoterpene hydrocarbons fraction exhibited a positive Pearson's correlation coefficient with all antioxidant assays. Leaves, often considered waste material, should be considered from a different point because they represent a matrix of indisputable interest., (© 2016 Verlag Helvetica Chimica Acta AG, Zürich.)

Unlabelled: The interest in medicinal plant research and in the aroma-therapeutic effects of essential oils in humans has increased in recent years, especially for the treatment of pathologies of relevant social impact such as Alzheimer's disease. The present study was taken up to evaluate the antioxidant capacity and the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activity of the peel essential oils from three Citrus species, C. aurantifolia Swingle, C. aurantium L., and C. bergamia Risso & Poit. Essential oils were analyzed by GC and GC-MS and they contain mainly limonene, α-pinene, β-pinene, γ-terpinene, and linalyl acetate. C. aurantifolia oil showed the highest radical scavenging activity on ABTS assay (IC₅₀ value of 19.6 μg/mL), while C. bergamia exhibited a good antioxidant activity evaluated by the β-carotene bleaching test (IC₅₀ = 42.6 μg/mL after 60 min of incubation). C. aurantifolia inhibited more selectively AChE. Obtained data suggest a potential use of Citrus oils as a valuable new flavor with functional properties for food or nutraceutical products with particular relevance to supplements for the elderly., Practical Application: The demonstrated antioxidant activity and procholinesterase properties of Citrus essential oils suggested their use as a new potential source of natural antioxidant to added as extra-nutrient for using in food industries as a valuable new flavor with functional properties for food or nutraceutical products with particular relevance to supplements for the elderly., (© 2011 Institute of Food Technologists®)

Since the past decade consumption of certain foods has been reported to have a positive effect on health. The object of the study was to determine for the first time the chemical composition and the antioxidant, anti-inflammatory and hypoglycemic potential of Citrus medica L. cv Diamante flowers, leaves and fruits (endocarp and mesocarp) at two maturity stages. Flowers and leaves were characterized by the highest total phenols and flavonoids content. A declining trend was observed during maturity of fruits for both phenols and flavonoids. The antioxidant activity evaluated by the β-carotene bleaching test showed a strong activity for flowers and endocarp of mature fruits with IC50 values of 2.8 μg/mL and 3.5 μg/mL, respectively, after 30 min of incubation. Interestingly, the mature fruits endocarp (IC50 value of 426.0 μg/mL) could inhibit α-amylase with an IC50 value 2-fold higher than immature fruits. None of the tested extracts affected the proliferation of human skin fibroblasts 142BR. The obtained results suggest a potential use of C. medica L. cv Diamante as new valuable Citrus species with functional properties for food or nutraceutical product on the basis of high content of phytochemicals., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The chemical composition of the essential oil of Citrus medica L. cv. Diamante peel obtained by hydrodistillation, cold-pressing and supercritical carbon dioxide extraction techniques was determined by GC/MS analysis. Forty-six components were fully characterised. Limonene and γ-terpinene were the major components of the oils obtained by hydrodistillation (HD) and cold-pressing (CP), while citropten was the major constituent in the oil obtained by supercritical carbon dioxide extraction (SFE). Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities were evaluated. The essential oil obtained by hydrodistillation exerted the highest inhibitory activity against BChE (IC₅₀ value of 154.6 µg mL⁻¹) and AChE (IC₅₀ value of 171.3 µg mL⁻¹. Interestingly, the oil obtained by cold-pressing exhibited a selective inhibitory activity against AChE. The essential oils have also been evaluated for the inhibition of NO production in LPS induced RAW 264.7 macrophages. The oil obtained by hydrodistillation exerted a significant inhibition of NO production with an IC₅₀ value of 17 µg mL⁻¹ (IC₅₀ of positive control 53 µg mL⁻¹).

Context: The search for innovative therapeutic approaches is gaining more interest in clinical oncology., Objective: In the present investigation we reported the chemical profile and the photo-induced cytotoxic activity of two endemic Calabrian Citrus species (Rutaceae): Citrus bergamia Risso & Poit. and Citrus medica L. cv. Diamante., Materials and Methods: Essential oils were obtained by hydrodistillation and analyzed by GC and GC/MS. In order to evaluate the cytotoxic activity two melanoma models, such as amelanotic melanoma C32 and malignant melanoma A375, were used., Results: The essential oil of C. bergamia was characterized by limonene, linalyl acetate, gamma-terpinene, linalool and beta-pinene as major components. The most abundant compounds of C. medica cv. Diamante oil were limonene, gamma-terpinene, citral, geranial, beta-pinene and alpha-pinene. Two coumarins, bergapten and citropten, were also identified in C. bergamia and C. medica cv. Diamante, respectively and tested for biological activity. Both C. bergamia and C. medica cv. Diamante oils exhibited a selective interesting activity against the A375 cell line with IC(50) values of 79.3 and 89.1 microg/mL, respectively, after 100 min exposure to UV irradiation. The strong antiproliferative activity demonstrated with bergapten (IC(50) value of 71.3 microg/mL after 20 min of irradiation) was not found with citropten., Discussion and Conclusion: Our study suggested that UV irradiation is effective in activating essential oils and in particular bergapten. This phototoxicity may be considered as a treatment option in some cases of lentigo maligna or lentigo maligna melanoma.

The present study showed for the first time the in vitro properties (antioxidant, hypoglycaemic and anticholinesterase) of Citrus medica L. cv. Diamante which belongs to the Rutaceae family. The n-hexane extract of Diamante citron peel is characterized by the presence of monoterpenes and sesquiterpenes. The most abundant constituents were two monoterpenes: limonene and gamma-terpinene. The extract showed significant antioxidant activity that was carried out using different assays (DPPH test, beta-carotene bleaching test and bovine brain peroxidation assay). Oxidative damage, caused by the action of free radicals, may initiate and promote the progression of a number of chronic diseases, including diabetes and Alzheimer's disease. Diamante citron peel extract showed hypoglycaemic activity and an anticholinesterase effect., (Copyright 2007 John Wiley & Sons, Ltd.)