Citrus Oils Research Articles

Identification of a new antinociceptive alkaloid isopropyl N-methylanthranilate from the essential oil of Choisya ternata Kunth

Mexican people employed infusion of leaves of Choisya ternata Kunth for their antispasmodic and "simulative properties". In the present study the detailed GC and GC-MS analyses of the essential oil of Choisya ternata Kunth (Rutaceae) were performed. The presence of a minor constituent isopropyl N-methylanthranilate (1) was revealed among other identified volatiles. A synthesis of 1 was undertaken in order to corroborate this find and obtain gram quantities that would allow the testing of its biological activity (peripheral and central antinociceptive activity). The oils were investigated by GC and GC-MS. Synthesized compounds were spectrally characterized (UV-Vis, IR, 1D and 2D NMR, MS). The obtained synthetic samples of compounds were assayed for peripheral and central antinociceptive activity in two models (effects on acetic acid induced writhing in mice and the hot plate test for nociception). Detailed GC and GC-MS analyses of the essential oil of Choisya ternata Kunth (Rutaceae) among 157 other identified volatiles revealed the presence of a minor constituent isopropyl N-methylanthranilate (1). Compound 1, named ternanthranin, is therefore detected as a natural product for the first time with a very restricted occurrence (samples of several citrus oils were screened for the presence of 1). The antinociceptive activities were assayed for ternanthranin, the two other synthetic analogs, methyl and propyl N-methylanthranilate, as well as the essential oil and the crude ethanol extract of the leaves. The results clearly demonstrate a very high (even significant at 0.3 mg/kg) dose dependent activity for the anthranilates (and the extracts). Isopropyl N-methylanthranilate showed the highest, while methyl N-methylanthranilate showed the lowest activity (with the methyl ester at 3 mg/kg still better than acetylsalicylic acid, at 200 mg/kg, in the first, or comparable with morphine, at 5mg/kg, in the second test). This study once again revealed that detailed investigations of plant species with ethnopharmacologically documented activity may yield new natural compounds-a new alkaloid (ternanthranin), a volatile simple anthranilate that can be considered responsible for the antinociceptive activity of the crude plant extracts.

Bilayer-Modifying Potential of Limonene and its Metabolites

Membrane protein function depends on lipid bilayer properties, which can be modified by small molecules. This may account for some of the undesired clinical effects of amphiphatic drugs that modify bilayer properties. In this study, we assessed whether D-limonene and its metabolites (perillyl alcohol, perillaldehyde, and perillic acid) alter lipid bilayer properties, as sensed by bilayer-spanning gramicidin (gA) channels, using a fluorescence assay and single-channel electrophysiology. D-limonene and its metabolites are terpenes that are found in a variety of foods, particularly citrus oils. They have been shown as potential cancer prevention and treatment agents and as antimicrobials. These terpenes are also used as solvents and flavor and fragrance agents. Given the wide range of biological functions of these hydrophobic/amphiphilic compounds, it becomes important to determine to what extent they alter bilayer properties. Using the fluorescence assay, we find that at micromolar concentrations (nominal concentrations): D-limonene decreases gA channel activity, perillyl alcohol and perillaldehyde increase activity, and perillic acid has no apparent effect. When examined using single-channel electrophysiology, each terpene increased gA channel lifetime and appearance rate. In the case of perillaldehyde and perillyl alcohol there is agreement between the two assays but not for D-limonene and perillic acid. We are exploring the basis for these differences. The changes in gA channel function (bilayer properties) were observed at low membrane concentrations (mole fraction ∼0.02-0.03), indicating that these terpenes are potent bilayer modifiers.

Effect of orange essential oil and its constitutes on late blight disease of potato plants under field conditions

Late blight caused by Phytophthora infestans is the most important disease attacking potato plants. Four concentrations of essential oils i.e. 0.0, 1.25, 2.5, 5.0 and 7.5 ml/l of Orange, Citral, Methyl antranate (MA), and Terbinol were tested for controlling late blight disease. Results indicate that all treatments except orange oil have an inhibitory effect against the linear growth of P. infestans. Complete reduction in linear growth was obtained with Citral and MA at concentrations of 5.0 and 7.5 ml/l. Other treatments showed moderate effect against P. infestans. In greenhouse experiments, results indicate that all treatments have protective and therapeutic effects against late blight disease except Orange oil which has a protective effect only. High reduction was obtained with Citral and MA at concentrations of 2.5 and 5.0 ml/l which reduced the disease severity by more than 77.1 and 62.8% when applied as protective and therapeutic treatments respectively. Moderate effect was obtained with orange oil and Citral at concentration of 7.5 ml/l for both treatments which reduced the disease severity by more than 65.7% when applied as protective treatments. Similar results were obtained under field coditions; results indicate that all treatments reduced the late blight severity during two growing seasons. High reduction was obtained with Citral and MA at concentrations of 2.5 and 5.0 ml/l which reduced the disease severity by more than 80.0%. As for potato yield, results indicate that all treatments increased potato yield during two growing seasons. A high increase was obtained with Citral and MA at concentrations of 2.5 and 5.0 ml/l which increased the potato yield by more than 59.1%. Other treatments showed a moderate increase. It could be suggested that some essential oils of citrus or their constituents might be used for controlling late blight disease potato plants under field conditions.

Insecticidal Activity against Bemisia Tabaci Biotype B of Peel Essential Oil of Citrus sinensis var. pear and Citrus aurantium Cultivated in Northeast Brazil

The fumigant action of peel essential oils of Citrus sinensis var. pear (pear orange = PO) and C. aurantium (bitter orange = BO) from the northeast of Brazil were evaluated against Bemisia tabaci biotype B and compared with eugenol as a positive control. The oil concentration in the PO at 8.5 microL/L of air caused 97% mortality, while the oil concentration of BO at 9.5 microL/L of air caused 99% mortality. However, the LC50 estimates for both oils (LC50 = 3.80 microL/L of air for PO and LC50 = 5.80 microL/L of air for BO) did not differ from each other, but they did when compared with eugenol (LC50 = 0.20 microL/L of air). Regarding their effects on oviposition, the Citrus oils showed concentration-response dependence, reducing the number of eggs as the concentration increased, which was not observed for eugenol. The minimum concentrations of the oils that caused a significant reduction in the egg lay were 3.5 and 7.0 microL/L of air for BO and PO, respectively. These results suggest that oils from PO and BO peels may be promising as models to develop new insecticides that might be applied into the integrated management of whiteflies.

Properties of microemulsions with mixed nonionic surfactants and citrus oil

Water/propylene glycol/sucrose laurate/ethoxylated mono-di-glyceride/citrus oil microemulsion systems were formulated and characterized using electrical conductivity, dynamic light scattering, and small angle X-ray scattering. The solubilization capacity of water in the oil is dependent on the surfactants mixing ratio (w/w). The free energy of solubilization ( Δ G s o ) for water-in-oil microemulsions were calculated and found to decrease with water content in the water-in-oil microemulsions region and increase in the oil-in-water region, Δ G s o decreased with increasing ethoxylated mono-di-glyceride content in the mixed surfactants. Static percolation phenomena were observed in these systems, and the water volume fraction percolation threshold was determined. The activation energy of conductive flow depends on the surfactants mixing ratio. The hydrodynamic diameter of the diluted microemulsions decreases with the increase in temperature. The periodicity and the correlation length those are characteristic lengths for the domain size of the microemulsions increase with the increase in the aqueous phase content.

Essential Oils and Antioxidants Derived From Citrus By-Products in Food Protection and Medicine: An Introduction and Review of Recent Literature

After a brief overview of the general production, market value, and uses of citrus by-products, this literature review will focus on the most highly refined “pharmaceutical grade” citrus oils and antioxidants that have been derived from peels or other fruit parts. Citrus oils have been used as a part of the perfume industry and in the practice of alternative medicine for a long time, but now there is a great deal of mainstream food processing and drug industry interest in them owing to the rediscovery or confirmation of some of their beneficial properties, as well their development for entirely new applications. Their roles as antimicrobial, immunomodulatory, and cancer chemopreventive or chemotherapeutic agents appear promising.

Essential oil deterpenation by solvent extraction using 1-ethyl-3-methylimidazolium 2-(2-methoxyethoxy) ethylsulfate ionic liquid

Taking into account that heat application can have undesirable effects in essential oil properties, liquid extraction comes up as a promising process instead of distillation for citrus oil deterpenation. In this work the suitability of using the ionic liquid 1-ethyl-3-methylimidazolium 2-(2-methoxyethoxy) ethylsulfate as a solvent for the extraction of linalool from citrus essential oil (which has been simulated as a mixture of limonene and linalool) has been analyzed. Liquid–liquid equilibrium data at three different temperatures (298.15 K, 308.15 K and 318.15 K) have been reported and successfully correlated using NRTL model. The best results were achieved using α = 0.1 for the systems at 298.15 K and 308.15 K and α = 0.2 at 318.15 K. The solute distribution ratio has showed values close to one and high values of selectivity have been achieved.

Acaricidal Activity against Tetranychus urticae and Chemical Composition of Peel Essential Oils of Three Citrus Species Cultivated in NE Brazil

The repellency and fumigant toxicities of the peel essential oils of Citrus sinensis var. pêra (LP), C. sinensis var. mimo (LM), and C. aurantium (LL) cultivated in northeast Brazil were evaluated against Tetranychus urticae. Analysis of the oils by GC and GC/MS led to the identification of twenty-eight components, which represented 99.9%, 99.7% and 99.3% of the total constituents of the LP, LM and LL oils, respectively. Limonene was the main component found in all three oils. Other main components were alpha-pinene (1.5% in LP; 1.4% in LM), myrcene (5.7% in LP; 5.9% in LM and 5.6% in LL) and linalool (2.4% in LP; 2.3% in LM and 3.9% in LL). The best repellency action was observed for LM at 2.0%, followed by LL oil and eugenol, both of them at 2.5%. The Citrus oils were less active than eugenol (LC50 = 0.004 microL/L air) and phosphine, which revealed 100% mortality at 2 x 10(-3) g/L (66.7% of the recommended dose). However, the most potent fumigant toxicity was found with LL oil, with an LC50 value of 1.63 microL/L air, followed by the oils from LM and LP with LC50 values of 2.22 microL/L air and 4.63 microL/L air, respectively. The associated fumigant and repellent properties of these Citrus peel oils, particularly those of C. aurantium and C. senensis var. mimo, could be used to advantage for the control of T. urticae.

Genuineness assessment of mandarin essential oils employing gas chromatography‐combustion‐isotope ratio MS (GC‐C‐IRMS)

Cold-pressed mandarin essential oils are products of great economic importance in many parts of the world and are used in perfumery, as well as in food products. Reconstituted mandarin oils are easy to find on the market; useful information on essential oil authenticity, quality, extraction technique, geographic origin and biogenesis can be attained through high-resolution GC of the volatile fraction, or enantioselective GC, using different chiral stationary phases. Stable isotope ratio analysis has gained considerable interest for the unveiling of citrus oil adulteration, detecting small differences in the isotopic carbon composition and providing plenty of information concerning the discrimination among products of different geographical origin and the adulteration of natural essential oils with synthetic or natural compounds. In the present research, the authenticity of several mandarin essential oils was assessed through the employment of GC hyphenated to isotope ratio MS, conventional GC flame ionization detector, enantioselective GC and HPLC. Commercial mandarin oils and industrial natural (declared as such) mandarin essential oils, characterized by different harvest periods and geographic origins, were subjected to analysis. The results attained were compared with those of genuine cold-pressed Italian mandarin oils, obtained during the 2008-2009 harvest season.

Inhibition of quorum‐sensing signals by essential oils

The role of quorum sensing (QS) is well known in microbial pathogenicity and antibiotic resistance. QS is responsible for motility, swarming, and biofilm production based on the signal molecules, e.g., acylated homoserine lactones (AHLs) produced by micro-organisms above certain population density. The inhibition of QS may reduce pathogenicity, antibiotic resistance and biofilm formation in systemic and local infections. The homoserine lactones and other transmitters contribute to antibiotic resistance and pathogenicity of several bacteria; consequently the inhibition of QS signals reduces the problem of resistance and virulence. Due to the increasing number of persistent non-treatable infections, there is an urgent need to develop new strategies to combat infections that destabilize bacterial communities in the host. The effect of essential oils on bacterial growth and QS were evaluated using the sensor strain Chromobacterium violaceum CV026 and N-acyl homoserine lactone (AHL) producing Escherichia coli ATTC 31298 and the grapevine colonizing Ezf 10-17 strains. Of the tested oils, rose, geranium, lavender and rosemary oils were the most potent QS inhibitors. Eucalyptus and citrus oils moderately reduced pigment production by CV026, whereas the chamomile, orange and juniper oils were ineffective.

Determination of Oxygen Heterocyclic Components in Citrus Products by HPLC with UV Detection

The study of oxygen heterocyclic compounds (coumarins, psoralens, polymethoxylated flavones) in natural matrices such as citrus oils is not easy due to the difficulty of obtaining standards at the required level of purity and the diversity of structures present in each kind of sample. In this work, standards were either isolated by preparative LC methods from citrus oils or synthesized, then characterized by their physicochemical parameters and spectroscopic techniques, and further used for qualitative and quantitative calculations in citrus essential oils and products made with them (Earl Grey tea, liquors, juices). An HPLC method using an innovative partially porous particle HPLC column enabled baseline separation of all analytes. The method developed was validated in terms of detection limit, quantitation limit, linearity, and precision as repeatability and intralaboratory reproducibility.

Immunochemical Screening of Pesticides (Simazine and Cypermethrin) in Orange Oil

Pesticide residue analysis in citrus oils is very important for their quality and marketing. This study assessed the reliability and sensitivity of enzyme-linked immunosorbent assays (ELISA) for simazine and cypermethrin screening in orange oil. Simazine was analyzed after extraction of the oil with methanolic phosphate buffer with a limit of quantitation (LOQ) of 40 microg/L for 1-fold and approximately 100 microg/L for 10-fold oils. Due to matrix effects the immunoanalysis of cypermethrin required hexane-acetonitrile partitioning followed by silica solid phase extraction. The method detected levels higher than 0.5 ppm (mg/L). This LOQ is lower than the U.S. EPA tolerance level (0.9 ppm) for cypermethrin in citrus oils. A good correlation (r(2) 0.99) between ELISA and LC-MS/MS was observed for the analysis of both analytes in 1-fold orange oil. Immunochemical screening can be used to reduce instrumental analysis costs by its use in preliminary orange oil screening.

The Effects of Rootstock on the Volatile Flavour Components of Page Mandarin [(C.Reticulata var dancy C. Paradisi var dancan) C. Clemantina] Juice and Peel

The effects of rootstock on the volatile flavour components of page mandarin juice and peel were investigated in this study. Juice flavour components were extracted by using Poly dimethyl silaxane membranes( PDMS ) and eluted by pentane dichloromethane and then analyzed by GC-FID and GC-MS. Peel flavour components were extracted by using cold-press and eluted by using n-hexane and then analyzed by GC-FID and GC-MS. Seventy-five juice components, sixty-eight green peel components and fourty- two red peel components including: aldehydes, alcohols, esters, ketons, monoterpens, sesquiterpens and acids were indentified and quantified. The major flavour components were linalool, limonene, octanal, decanal, a-pinene, sabinene, myrcene,- elemen and germacren-D. It is of interest to point out that juice and peel oil from fruit grown on Citrumelo Swingle and Yuzu showed the highest content of aldehydes. Since the aldehyde content of citrus oil is considered as one of the more important indicators of high quality, rootstock apparently has a profound influence on Page Mandarin juice and peel oil quality.

In vitroAntilisterial Effects of Citrus Oil Fractions in Combination with Organic Acids

The objectives of this study were to screen activity of citrus essential oil fractions (EOs) alone and in combination with organic acids against 2 species of Listeria. Five citrus EOs were initially screened by disc diffusion assay for antibacterial activity. Cold pressed terpeneless Valencia orange oil (CP terpeneless oil) had the strongest bacteriostatic (MIC) and bactericidal (MBC) properties at 0.55% and 1.67%, respectively. Four organic acids were tested for effectiveness against Listeria. Citric and malic acids proved to be the most effective with MBC of 1.1% alone. Assays were conducted to determine synergistic effects of EOs and citric or malic acids. There was a significant decrease in MIC and MBC to 0.04% EO plus 0.12% malic or citric acid. EOs from citrus paired with organic acids offer the potential as an all-natural antimicrobial for improving the safety of all-natural foods.

Chemical Composition of Mandarin (C. reticulata L.), Grapefruit (C. paradisi L.), Lemon (C. limon L.) and Orange (C. sinensis L.) Essential Oils

Citrus oils are a complex mixture of more than a hundred components of differing chemical natures. The study of the physiologically active components of citrics and their contribution to human health is a growing research field. The aim of this work was to determine the chemical composition of four citrus oils: mandarin (C. reticulata L.), grapefruit (C. paradisi L.), lemon (C. limon L.), and orange (C. sinensis L.). The oils were chemically analysed and identified by Gas chromatography mass spectrometry (GC-MS). The principal components of the essential oils were as follows. Mandarin: limonene (74.7 %) and λ-terpinene (15.7 %); lemon: limonene (69.9 %) and β-pinene (11.2 %); orange: limonene (94.9 %) and β-myrcene (1.16 %); grapefruit: limonene (96.2 %) and myrcene (1.4 %). In all four analysed citrus oils limonene was the most abundant component. The great variability may have been due to several factors, among them the particular varieties studied, the geographical location, season and environmental factors, such as soil type and climate, genetic factors processing and extraction method and the part of the plant used to extract the oil.

Repellent activity of citrus oils against the cockroaches Blattella germanica, Periplaneta americana and P. fuliginosa

The repellent efficacy of 17 essential oils against the German cockroach, Blattella germanica was examined using a T-tube olfactometer. Five oils repelled B. germanica with good efficacy, ranging from 70.0 to 96.7%. Four of these oils, grapefruit, lemon, lime, and orange, were from the citrus family Rutaceae. These citrus essential oils showed similar repellent activity against two more cockroach species, such as Periplaneta americana and P. fuliginosa. Gas chromatography (GC) and GC-mass spectrometry analyses revealed that the major components responsible for the repellent activity of the citrus oils were limonene, β-pinene and γ-terpinene. Limonene appears to be the main component responsible for the repellent activity rather than β-pinene and γ-terpinene. The repellent efficacy of these components varied with different doses and the cockroach species tested. It is likely that minor components of the oils also contributed to the overall repellent activity of citrus essential oils, except orange oil. The activity of orange oil is almost solely attributed to the activity of limonene. Also, the repellent activity of citrus oil and that of each of the terpenoids makes little difference to the efficacy of a repellant against the three species of cockroaches.

Chemical Composition of Peel Essential Oils of Sweet Oranges (Citrus sinensis) from Uganda and Rwanda

The chemical composition of cold-pressed peel essential oils of common sweet oranges (Citrus sinensis [L.] Osbeck) from Uganda and Rwanda were analyzed by GC and GC-MS and a total of 51 and 55 volatile chemical components were identified respectively. The major chemical groups were monoterpene hydrocarbons (94.4 and 97.3 %), terpene alcohols (1.4 and 1.0 %), aliphatic aldehydes (1.6 and 0.8 %) and terpene aldehydes (1.4 % and trace). The main compounds were limonene; 87.9 and 92.5 %, myrcene; 2.4 and 2.0 %, α-pinene; 0.5 and 2.4 %, linalool; 1.2 and 0.9 %, octanal; 1.3 and 0.6 % and decanal, 0.2 %. Some of the compounds present in the Ugandan oil, including iso-amyl acetate, iso-safrole, iso-amyl isovalerate, (E)-sabinene hydrate and methyl caprate were absent in Rwandan oil. The Rwanda Citrus oil contains methyl isobutyrate, α-copaene, myrcenol, neryl acetate, geranyl propionate and perilly alcohol which were not detected in Uganda Citrus oil.

In vitro inhibition of vancomycin-susceptible and vancomycin-resistant Enterococcus faecium and E. faecalis in the presence of citrus essential oils

Glycopeptide-resistant Enterococcus (GRE) is an important healthcare-acquired infection (HCAI) which costs the healthcare service many millions of pounds worldwide. In this study, lemon (Citrus limon), sweet orange (Citrus sinensis) or bergamot (Citrus bergamia) essential oils (EO) and their vapours, alone and in combination, are tested for their antimicrobial activity against vancomycin-resistant and vancomycin-sensitive strains of E. faecium and E. faecalis. A blend of 1:1 (v/v) orange and bergamot EO was the most effective of the oils and/or blends tested with a minimum inhibitory concentration (MIC), at 25˚C and pH 5.5, of 0.25–0.5% (v/v) and a minimum inhibitory dose (MID) of 50 mg/L, at 50˚C at pH 7.5, when viable counts reduced by 5.5–10 log10 colony forming units (cfu)/mL, suggesting that this blend of citrus oils is effective under a range of conditions for inhibiting the growth and survival of E. faecalis, E. faecium and VRE.

Citrus Products Decrease Growth of E. coli O157:H7 and Salmonella Typhimurium in Pure Culture and in Fermentation with Mixed Ruminal Microorganisms In Vitro

Orange peel and orange pulp are by-products that are included in feedlot and dairy cattle diets because of their low cost and high nutritional quality. The antimicrobial activity of citrus oils has been reported previously. The present study was carried out to determine whether these citrus by-products exert antimicrobial effects on Escherichia coli O157:H7 and Salmonella Typhimurium populations that are found in cattle gastrointestinal tracts. The growth of pure cultures (n = 3) of E. coli O157:H7 and Salmonella Typhimurium were reduced (p < 0.05) by addition of 2% (w/v) orange pulp and orange peel. Ruminal fluid was collected from cattle (n = 2) and E. coli O157:H7 or Salmonella Typhimurium were added. The addition of orange pulp and peel to in vitro mixed ruminal microorganism fermentations (n = 3) demonstrated that both orange pulp and peel reduced E. coli O157:H7 and Salmonella Typhimurium populations at least 2 log(10) in mixed ruminal fluid fermentations. Addition of orange pulp reduced (p < 0.05) E. coli O157:H7 populations from 10(5) to 10(2) colony-forming units (CFU)/mL and Salmonella Typhimurium populations (p < 0.05) from 10(4) to 10(2) CFU/mL. These results indicate that orange pulp and/or peel included in ruminant diets could decrease ruminal populations of foodborne pathogenic bacteria. Further research is needed to determine whether the antimicrobial activity of orange products against E. coli O157:H7 or Salmonella Typhimurium is expressed in the lower gastrointestinal tract.

Comparative efficacy of sweet orange, &lt;i&gt;Citrus sinensis&lt;/i&gt;(l) rind powder and oil for the control of maize weevil, &lt;i&gt;Sitophilus zeamais&lt;/i&gt; (motschulsky).

Sweet orange, Citrus sinensis((L.) rind powder and oil were evaluated for the control of maize weevil, Sitophilus zeamais(Mot.) under ambient laboratory conditions (28 ± 2o C and 75 ± 20% R.H.). Experiments consisted of exposing adult S. zeamais to both the powder and oil for 42 days. Mortality counts were taken from the first day after treatment (DAT) until 42 DAT. The result indicated that pulverized orange rind had no significant mortality effect on adult S. zeamais (P&#8805;0.05) resulting in severe damage of the grains and weight loss. The Weevil Perforation Index (WPI) for all the dosages of the powder was greater than 50%, indicating reduced protectant effect; while the rind oil treatment resulted in significant mortality of adult S. zeamais (P&#8804; 0.05). There was significant reduction of grain damage when protected with oil extract. The WPI of all the dosages was below 50%, which confirmed the efficacy of the orange rind oil. The C. sinensis rind oil, not the powder can therefore be used for the storage of maize grains.Agro-Science Vol. 7 (1) 2008: pp. 9-14