Citrus Essential Oils in Aromatherapy: Therapeutic Effects and Mechanisms

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.

Product diversification from pomelo peel. Essential oil, Pectin and semi-dried pomelo peel

Currently, agriculture has shifted to green production, in which the recycling of post-production by-products is a key issue. In the present work, by-products such as pomelos were studied to promote consumption and enhance the value of pomelo. From pomelo material, essential oils extracted from pomelo peels, pectin, and drying pomelo products have been diversified. In the extraction process of essential oils, the hydrodistillation method was applied in conjunction with the response surface method to obtain the optimal conditions of influence factors. These essential oils were quantified as well as determined for components by GC-MS. The pectin recognition process was done by immersion method in HCl acid (pH 2) and the drying process was made with a heat pump dryer under the effects of drying temperature, drying time and wind rate. The results of the essential oil products reached the highest (0.88 ±0.006 g) at the material size of 3 mm, the distillation time of 27 min, and the ratio of raw materials/solvents of 1/12 g/mL. The main components found in pomelo peeling essential oils included limonene (71.768%), γ-terponene (12,847%), α-Phellandrene (2.979%), β-myrcene (2.668%), 1R-α-pinene (2,656%), and β-pinene (1,191%). The pectin content was the highest under the temperature of 90 °C, extraction time of 60 min and ratio/solvent ratio of 1:32 g/mL. Under these extraction conditions, 48% of concentrated pectin content was obtained. Surveying conditions for drying white pomelo peels are capable of reversing: refunded drying pomelos are drying heat pumps in the following conditions: 50 °C drying temperature, the drying time of 90 min, and wind rate of 12 m/s. Product with hardness 309.862 N.

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

Hydro-distillation assisted by electromagnetic induction heating (H-EMIH) was employed to extract essential oil (EO) from Algerian fresh orange peels (Citrus sinensis). H-EMIH was compared with conventional hydro-distillation (C-H) in terms of hydro-distillation time, yield, chemical composition and, antibacterial and antioxidant activities. It was found that extraction of EO with H-EMIH gave a maximal yield of 3.77% in 35 min whereas C-H gave 2.72% in 41 min. The extracts obtained by both techniques were analyzed by Gas Chromatography-Mass Spectrometry. Their chemical compositions are relatively similar; limonene and β-myrcene were found as the principal compounds. The antioxidant activity results demonstrated that EO extracted by H-EMIH showed the highest capacity of radical scavenging than EO isolated by C-H process. Otherwise, it was found that EO extracted by H-EMIH exhibited an antimicrobial potential slightly higher than that extracted by C-H.

Enhancing the oxidative stability of algal oil emulsions by adding sweet orange oil: Effect of essential oil concentration

The effects of sweet orange essential oil (SOEO) concentration (0-12.5% of oil phase) on the physical stability, oxidative stability, and interfacial composition of algal oil-in-water emulsions containing sodium caseinate-coated oil droplets was examined. SOEO addition had no influence on the microstructure and physical stability of the algal oil emulsions. The addition of SOEO enhanced the oxidation stability of algal oil emulsion. As an example, the values of algal oil emulsions with 0 and 10% SOEO were 198 and 100 mmol/kg algal oil after 16 days of accelerated oxidation, respectively. The absorbed protein level was higher in the algal oil emulsion containing 10% SOEO (70%) than in 0% SOEO (57%). This result suggested that the presence of SOEO enhanced the interfacial thickness, possibly by interacting with the casein molecules. A thicker protein layer may have helped to retard the oxidation of the omega-3 oils inside lipid droplets.

Evaluation of the Effects of Chronic Administration of Citrus aurantium Essential Oil on the Development of Tolerance and Dependence to Morphine

Background: Long-term exposure to opioids may lead to physical dependence and tolerance. The purpose of this study was to investigate the effects of Citrus aurantium essential oil (CEO) on the morphine-induced tolerance and dependence. Methods: To evaluate morphine tolerance, the experiments were carried out in 6 rat groups (n=8) in the weight range of 225-275 g. The control group received morphine (10 mg/kg/day) and the test groups received morphine with the different doses of essential oil (CEO 20, 40 and 80 mg/kg/day) or 4 mL/kg of essential oil vehicle (KolliphorÒ HS15 30% in normal saline that adjusted in pH=7.4 with phosphate buffer) intraperitoneally. The hot-plate test was carried out every other day, 90 minutes after the injections. To examine morphine withdrawal, male Wistar rats were divided into seven groups (n=8) randomly, including: morphine sulphate, CEO (20, 40 and 80 mg/kg) + morphine, vehicle of CEO + morphine. The rats were rendered morphine-dependent by injection of additive doses of morphine subcutaneously for 9 days. The procedure of the morphine administration was as following protocol: day1: 5 mg/kg/12h, day 2 and 3: 10 mg/kg/12h, day 4 and 5: 15 mg/kg/12h, day 6 and 7: 20 mg/kg/12h and day 8 and 9: 25 mg/kg/12h. In the 9th day, 2 hours after the last dose of morphine, naloxone (4 mg/kg) was injected intraperitoneally. Some withdrawal behaviors were counted for 60 minutes. Results: Morphine tolerance was completed after 5 days in the control group. The vehicle group showed tolerance on the 9th day (p-value=0.991), 20mg group in the 13th day (p-value to control=0.010, to vehicle=0.049), 40 mg group on the 15th day (p-value to control and vehicle<0.001) and 80 mg group on the 13th day (p-value to control= 0.001, to vehicle= 0.007). The results showed that CEO could reduce the morphine withdrawal syndrome and total withdrawal score (TWS). Intraperitoneally injection of CEO in two doses (40 mg/kg with p<0.001 and 80 mg/kg with p<0.01) significantly reduced the TWS in comparison to the morphine+vehicle treated group. Conclusion: The results indicated that chronic administration of C. aurantium essential oil extracted had beneficial effects in reducing morphine withdrawal syndrome and could significantly delay tolerance to morphine.

Protective effect of essential oil from Citrus limon against aspirin-induced toxicity in rats

The present study is planned to examine the antioxidant activity (AA) and the protective effect of the essential oil of Citrus limon (EOC) against aspirin-induced histopathological changes in the brain, lung, and intestine of female rats. For this purpose, 28 albino rats were classified to control group (group C), aspirin group (group A), EOC group (group EOC), and pretreatment with EOC and treated with aspirin group (group EOC + A). The antioxidant activities of EOC were evaluated by three different assays including reducing power, β-carotene, and scavenging of hydrogen peroxide (H2O2). Our results found that EOC represents, respectively (0.064 ± 0.013 and 0.027 ± 00 mg Quer E/100 µL), of flavonoid and flavonol. Then, it exhibited a potential activity of reducing power (at 300 mg/mL, which was found to be 0.82 ± 0.07), β-carotene-linoleic acid (AA% = 69.28 ± 3.5%), and scavenging of H2O2 (IC50 = 0.23 ± 0.008 mg/mL). In vivo, aspirin given to rats at the dose of 600 mg/kg body weight induced histomorphological damage in brain, lung, and intestine. However, our data found that the pretreatment with EOC offered a significant protection against the injury induced by aspirin. It can be concluded that the protective effect of EOC can be due to its antioxidant activities.

Optimizing the Pomelo Oils Extraction Process by Microwave-Assisted Hydro-Distillation Using Soft Computing Approaches

Pomelo (Citrus grandis .Linn Osbeck) oils is becoming more and more popular for everyone because it has great benefits. However, the efficiency of essential oil extraction process depends on the method and is influenced by a number of factors. Microwave-assisted hydro-distillation and Response Surface Methodology are selected for extracting and optimizing the factors affect the yield of the pomelo oil. The pomelo oil has the optimum yield was 4.5% when extracted with a water and peels ratio of 3,119: 1 (ml/g) for time extraction of 117.336 (minutes) at a microwave power of 403.115 (W) with high reliability (R2 = 0.9831)

Volatile Profiles in Cold-Pressed Peel Oil from Korean and Japanese Shiranui (Citrus unshiuMarcov. ×C. sinensisOsbeck ×C. reticulataBlanco)

A comparison of the volatile profiles between Korean and Japanese Shiranui cold-pressed peel oil was performed by GC and GC-MS. Limonene was the most abundant in the Japanese (91.8%) and Korean (86.4%) oil. Alcohols accounted for 1.8% in the Korean oil, and 0.2% in the Japanese oil, in which the respective linalool levels were 1.2% and 0.1%. The level of aldehydes was also higher in the Korean oil (1.6%) than in the Japanese oil (0.7%).

Volatile constituents and antioxidant activity of peel, flowers and leaf oils of Citrus aurantium L. growing in Greece

The volatile constituents of the essential oils of the peel, flower (neroli) and leaves (petitgrain) of bitter orange (Citrus aurantium L.) growing in Greece were studied by GC-MS. The analytical procedures enabled the quantitative determination of 31 components. More specifically, the components of the essential oils identified were: twelve in the peel, twenty-six in the flowers, and twenty and sixteen in old and young leaves, respectively. The major constituents of the different parts of Citrus aurantium L. essential oils were: β-pinene (0.62%-19.08%), limonene (0.53%-94.67%), trans-β-ocimene (3.11%-6.06%), linalool (0.76%-58.21%), and α-terpineol (0.13%-12.89%). The DPPH test demonstrated that the essential oils in the old leaves had the maximum antioxidant activity, followed by the flowers, young leaves and the peel in that order. This study updates the data in the literature on the essential oils of bitter orange, and provides information on the composition of the oils for a further evaluation of this product.