Chemical composition, antimicrobial and antioxidant activities of Algerian Citrus sinensis essential oil extracted by hydrodistillation assisted by electromagnetic induction heating

Application of nanoparticles entrapped orange essential oil to inhibit the incidence of phytopathogenic fungi during storage of agroecological maize seeds

The demand for sustainable, healthy, and pesticide-free food has grown in recent years. Agroecological seeds cannot receive chemical treatment, as pesticides present toxicological and environmental risks, requiring the development of alternative methods for disease control, such as the use of essential oils. In this study, orange essential oil was extracted and encapsulated in zein nanoparticles by the nanoprecipitation method. The nanoparticles were tested for the antifungal activity on agroecological maize seeds and for the mycelial sensitivity of Stenocarpella macrospora. The synthesized nanoparticles presented good encapsulation efficiency (99 %) of orange essential oil rich in D-limonene, conferring high antioxidant activity to the loaded nanoparticles. The release profile indicated a pseudo-Fickian mechanism governed by diffusion, explained according to the Korsmeyer-Peppas model. The dynamic light scattering, and transmission electron microscopy showed spherical nanoparticles with particle size lower than 200 nm. The nanoparticles containing orange essential oil inhibited the incidence of Fusarium during the storage of agroecological maize seeds. The mycelial sensitivity against Stenocarpella macrospora showed that the encapsulated essential oil was more effective in inhibiting the fungus when compared to the non-encapsulated oil. Therefore, the nanoparticles containing encapsulated orange essential oil can be effectively applied as an antifungal material for the conservation of agroecological maize seeds, contributing to the development of sustainable agricultural biotechnology with pesticide-free products.

Citrus sinensis Essential Oils an Innovative Antioxidant and Antipathogenic Dual Strategy in Food Preservation against Spoliage Bacteria

The present study evaluates the chemical compositions and antioxidant and antipathogenic properties of commercial orange (Citrus sinensis (L.) Osbeck) essential oils obtained using the cold-press method (EOP) and the cold-press method followed by steam distillation (EOPD). The chemical compositions of the volatilizable fractions, determined by gas chromatography-mass spectrometry, were similar in both samples. A relatively large amount of γ-terpinene was found in the EOPD (1.75%) as compared to the EOP (0.84%). Monoterpene hydrocarbons with limonene (90.4-89.8%) followed by myrcene (3.2-3.1%) as the main compounds comprised the principal phytochemical group. The non-volatile phenolics were eight times higher in the EOP than in the EOPD. Several assays with different specificity levels were used to study the antioxidant activity. Although both essential oils presented similar reducing capacities, the radical elimination ability was higher for the EOP. Regarding the antipathogenic properties, the EOs inhibited the biomass and cell viability of Staphylococcus aureus and Pseudomonas aeruginosa biofilms. Furthermore, both EOs similarly attenuated the production of elastase, pyocyanin, and quorum-sensing autoinducers as assessed using Gram-negative bacteria. The EOP and EOPD showed important antioxidant and antipathogenic properties, so they could represent natural alternatives to extend the shelf life of food products by preventing oxidation and contamination caused by microbial spoilage.

Citrus By-Products: Valuable Source of Bioactive Compounds for Food Applications

Citrus production produces about 15 million tons of by-products/waste worldwide every year. Due to their high content of bioactive compounds, several extraction techniques can be applied to obtain extracts rich in valuable compounds and further application into food applications. Distillation and solvent extraction continues to be the most used and applied extraction techniques, followed by newer techniques such as microwave-assisted extraction and pulsed electric field extraction. Although the composition of these extracts and essential oils directly depends on the edaphoclimatic conditions to which the fruit/plant was exposed, the main active compounds are D-limonene, carotenoids, and carbohydrates. Pectin, one of the most abundant carbohydrates present in Citrus peels, can be used as a biodegradable polymer to develop new food packaging, and the extracted bioactive compounds can be easily added directly or indirectly to foods to increase their shelf-life. One of the applications is their incorporation in active food packaging for microbiological and/or oxidation inhibition, prolonging foods' shelf-life and, consequently, contributing to reducing food spoilage. This review highlights some of the most used and effective extraction techniques and the application of the obtained essential oils and extracts directly or indirectly (through active packaging) to foods.

Separation and evaluation of potential antioxidant, analgesic, and anti-inflammatory activities of limonene-rich essential oils from Citrus sinensis (L.)

The peel of Citrus sinensis (L.) Osbeck is a source of essential oils, particularly limonene, which is this plant’s characteristic molecule. The main goal of this study was to test the potential analgesic and anti-inflammatory properties of limonene-rich essential oils derived from the peel of C. sinensis L. (orange) in vivo, as well as their antioxidant activity in vitro. Carrageenan-induced paw edema in Wistar rats and the formalin test in Swiss albino mice were used to examine anti-inflammatory activity. The analgesic activity was assessed using hot plate and acetic acid writhing tests, while the antioxidant activity was assessed using the 1,1-diphenyl-2-picrylhydrazyl and ferric reducing antioxidant power methods. The essential oil (EO) safety was determined using an acute toxicity experiment on mice. The phytochemical analysis confirmed the existence of limonene as the primary molecule (88.94%), and in vivo experiments revealed that the EO had a significant pain and inflammation-relieving effect, especially at the dose of 50 mg/kg, when compared to the used control drugs. The acute toxicity evaluation reported this EO’s safety. This study contributes to the pharmacological valorization of the peel of C. sinensis L., confirming that, in addition to its numerous cosmetic and industrial uses, it may be effective in the treatment of inflammatory and pain-related illnesses.

Comparative Chemical Profiling and Biological Potential of Essential Oils of Petal, Choke, and Heart Parts of Cynara scolymus L. Head

The essential oil and macroelemental composition of different parts of flower bud (petal, choke, and heart) of Cynara scolymus L. were explored and compared using gas chromatography mass spectrometry (GC-MS) and inductively coupled plasma mass spectrometry (ICP-MS). Overall, 62 organic components were detected in the flower bud based on mass spectra characteristics and retention indices. The essential oil extracted from the petals, choke, and bud showed the presence of thirty-one, twenty-one, and twenty-one compounds, respectively, with linoleic acid and palmitic acid as the major components. 21 components were identified in the oil of the petals, comprising 94.45% of the total oil, in which linoleic acid methyl ester, palmitic acid methyl ester, octadecanoic acid methyl ester, O-α-d-glucopyranoside, and heptyl oct-3-yl ester were the major constituents. Twenty-one compounds, representing 89.13% of the total oil, were detected in the choke oil. Linoleic acid methyl ester, palmitic acid methyl ester, and 2-methyl-1-hexadecanol were the main components. However, the edible heart oil contains twenty compounds, comprising 86.84% of the total oil. Cyclopropane butanoic acid, linoleic acid, methyl ester, and palmitic acid were the major constituents. The analysis executed by ICP-MS revealed the presence of significant amounts of various inorganic elements in all the three samples. The extracted essential oils were tested for antibacterial, antioxidant, and anticancer activities. The results showed that the oil extracted from the petals of C. scolymus flower bud displayed the highest antibacterial, antioxidant, anti-inflammatory, and anticancer effects, as compared to choke and heart oils.