Showing papers on "Citral published in 2011"
TL;DR: Studies indicate that Cymbopogon citratus possesses various pharmacological activities such as anti-amoebic, antibacterial, antidiarrheal, antifilarial, antiifungal and anti-inflammatory properties, which are very encouraging and indicate that this herb should be studied more extensively to confirm these results and reveal other potential therapeutic effects.
Abstract: Cymbopogon citratus, Stapf (Lemon grass) is a widely used herb in tropical countries, especially in Southeast Asia. The essential oil of the plant is used in aromatherapy. The compounds identified in Cymbopogon citratus are mainly terpenes, alcohols, ketones, aldehyde and esters. Some of the reported phytoconstituents are essential oils that contain Citral α, Citral β, Nerol Geraniol, Citronellal, Terpinolene, Geranyl acetate, Myrecene and Terpinol Methylheptenone. The plant also contains reported phytoconstituents such as flavonoids and phenolic compounds, which consist of luteolin, isoorientin 2'-O-rhamnoside, quercetin, kaempferol and apiginin. Studies indicate that Cymbopogon citratus possesses various pharmacological activities such as anti-amoebic, antibacterial, antidiarrheal, antifilarial, antifungal and anti-inflammatory properties. Various other effects like antimalarial, antimutagenicity, antimycobacterial, antioxidants, hypoglycemic and neurobehaviorial have also been studied. These results are very encouraging and indicate that this herb should be studied more extensively to confirm these results and reveal other potential therapeutic effects.
337 citations
TL;DR: All the six terpenoids tested exhibit excellent synergistic activity with fluconazole against a flu Conazole resistant strain of C. albicans, which may find use in antifungal chemotherapy, not only as antIfungal agents but also as synergistic agents along with conventional drugs like fluconAZole.
243 citations
TL;DR: It is suggested that encapsulation of citral in emulsions and the addition of the appropriate antioxidants (β-carotene, tanshinone, and black tea extract) could greatly enhance citral's chemical stability during storage.
Abstract: The aim of the present study was to investigate the effects of oil-in-water (O/W) nanoemulsions combined with six different natural antioxidants on the stability of citral. Acidic emulsions (lecithin-stabilized palm kernel lipid in pH 3 buffer) containing 1000 ppm citral and 1000 ppm antioxidants (black tea extract, ascorbic acid, naringenin, tangeretin, β-carotene, and tanshinone) were stored at 25 and 50 °C, respectively. The emulsions with and without antioxidants were analyzed by solid phase microextraction gas chromatography (SPME-GC) to monitor the degradation process of citral and the formation of different off-flavor compounds, such as α,p-dimethylstyrene and p-methylacetophenone. The results suggested that encapsulation of citral in emulsions and the addition of the appropriate antioxidants (β-carotene, tanshinone, and black tea extract) could greatly enhance citral's chemical stability during storage.
80 citations
TL;DR: In this article, the effect of lemongrass and citral on IL-1β, IL-6, and IL-10 was analyzed in vitro, as well as before or after LPS incubation.
80 citations
TL;DR: In this article, the effect of Sn addition to Pd on the selective liquid-phase hydrogenation of citral to α,β-unsaturated alcohols (UA: nerol and geraniol) was examined.
72 citations
TL;DR: It is suggested that essential oils obtained from certain aromatic plants have potential as fumigants for stored product pests and decreasing longevity effect of marjoram and lemon was more prominent compared with other essential oils.
Abstract: The chemical constituents of some essential oils extracted from aromatic plants (savory, Satureja thymbra L.; Turkish oregano, Origanum onites L.; myrtle, Myrtus communis L.; marjoram, Origanum majorana L.; laurel, Laurus nobilis L.; lemon, Citrus limon L.; sticky goosefoot, Chenopodium botrys L.; and tansy, Tanecetum armenum [DC.] Suchultz Bip.) were analyzed by gas chromatography-mass spectrometry. Fumigant toxicity of volatile compounds was tested against Mediterranean flour moth, Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae), eggs and adults. Percentage of mortality and longevity of E. kuehniella adults were estimated after essential oil treatments. LC50 and LC99 values were determined for each exposure time for each essential oil. Marjoram and lemon oils were the most effective of all the essential oils tested. The major components were linalool, 1.8-cineole, citral, 2-(4a.8-dimethyl-1.2.3.4.4a.5.6.7-octahydro-naphthalen-2-yl)-prop-2-en-l-ol, and p-cymene for marjoram, laurel, lemon, goosefoot, and tansy, respectively. The LC50 and LC99 values were estimated as 3.27 and 5.13 microl liter(-1) air for marjoram and 4.05 and 5.57 microl liter(-1) air for lemon essential oils at the longest exposure time. Decreasing longevity effect of marjoram and lemon was more prominent compared with other essential oils. We suggest that essential oils obtained from certain aromatic plants have potential as fumigants for stored product pests.
57 citations
TL;DR: The results support the notion that anointing by vertebrates with citrus-derived chemicals deters ticks and suggest that some topically applied compounds are converted into more potent arthropod deterrents when oxidized on the integument of anointed animals.
Abstract: Some birds and mammals roll on or wipe themselves with the fruits or leaves of Citrus spp. or other Rutaceae. These anointing behaviors, as with anointing in general, are thought to function in the topical acquisition of chemicals that deter consumers, including hematophagous arthropods. We measured avoidance and other responses by nymphal lone star ticks (Amblyomma americanum) and adult female yellow fever mosquitoes (Aedes aegypti) to lemon peel exudate and to 24 volatile monoterpenes (racemates and isomers), including hydrocarbons, alcohols, aldehydes, acetates, ketones, and oxides, present in citrus fruits and leaves in order to examine their potential as arthropod deterrents. Ticks allowed to crawl up vertically suspended paper strips onto a chemically treated zone avoided the peel exudate and geraniol, citronellol, citral, carveol, geranyl acetate, α-terpineol, citronellyl acetate, and carvone. Ticks confined in chemically treated paper packets subsequently were impaired in climbing and other behaviors following exposure to the peel exudate and, of the compounds tested, most impaired to carveol. Mosquitoes confined in chambers with chemically treated feeding membranes landed and fed less, and flew more, when exposed to the peel exudate than to controls, and when exposed to aldehydes, oxides, or alcohols versus most hydrocarbons or controls. However, attraction by mosquitoes in an olfactometer was not inhibited by either lemon peel exudate or most of the compounds we tested. Our results support the notion that anointing by vertebrates with citrus-derived chemicals deters ticks. We suggest that some topically applied compounds are converted into more potent arthropod deterrents when oxidized on the integument of anointed animals.
55 citations
TL;DR: Both EOs protected bacterial cells against bleomycin-induced genotoxicity and Antigenotoxicity in the two L. alba chemotypes was related to the major compounds, citral and carvone, respectively.
Abstract: The present work evaluated the chemical composition and the DNA protective effect of the essential oils (EOs) from Lippia alba against bleomycin-induced genotoxicity. EO constituents were determined by Gas Chromatography/Mass Spectrometric (GC-MS) analysis. The major compounds encountered being citral (33% geranial and 25% neral), geraniol (7%) and trans-β-caryophyllene (7%) for L. alba specimen COL512077, and carvone (38%), limonene (33%) and bicyclosesquiphellandrene (8%) for the other, COL512078. The genotoxicity and antigenotoxicity of EO and the compounds citral, carvone and limonene, were assayed using the SOS Chromotest in Escherichia coli. The EOs were not genotoxic in the SOS chromotest, but one of the major compound (limonene) showed genotoxicity at doses between 97 and 1549 mM. Both EOs protected bacterial cells against bleomycin-induced genotoxicity. Antigenotoxicity in the two L. alba chemotypes was related to the major compounds, citral and carvone, respectively. The results were discussed in relation to the chemopreventive potential of L. alba EOs and its major compounds.
52 citations
TL;DR: The findings collectively raise the interesting possibility that the OR serves as a molecular logic gate when mammalian ORNs are activated by natural, complex mixtures containing both excitatory and inhibitory odorants.
Abstract: Phosphoinositide signaling, in particular, phosphoinositide 3-kinase (PI3K) signaling, has been implicated in mediating inhibitory odorant input to mammalian olfactory receptor neurons (ORNs). To better understand this phenomenon we investigated PI3K-dependent inhibition between single odorant pairs. The concentration-dependent inhibition of the response of native rat ORNs to octanol by citral is PI3K dependent; blocking PI3K activity with the β and γ isoform-specific inhibitors AS252424 (5-[5-(4-fluoro-2-hydroxy-phenyl)-furan-2-ylmethylene]-thiazolidine-2,4-dione) and TGX221(7-methyl-2-(4-morpholinyl)-9-[1-(phenylamino)ethyl]-4H-pyrido [1,2-a]pyrimidin-4-one) eliminated or strongly reduced the inhibition. Interestingly, blocking PI3K also changed the apparent agonist strength of the otherwise noncompetitive antagonist citral. The excitation evoked by citral after blocking PI3K, could be suppressed by the adenylate cyclase III (ACIII) blockers MDL12330A (cis-N-(2-phenylcyclopentyl)-azacyclotridec-1-en-2-amine hydrochloride) and SQ22536 [9-(tetrahydro-2-furanyl)-9H-purin-6-amine], indicating that citral could also activate ACIII, presumably through the canonical olfactory receptor (OR). The G-protein G(β)γ subunit blockers suramin (8,8'-[carbonylbis[imino-3,1-phenylen ecarbonylimino(4-methyl-3,1-phenylene)carbonylimino]]bis-1,3,5-naphthalenetrisulfonic acid), gallein (3',4',5',6'-tetrahydroxyspiro[isobenzofuran-1(3H),9'-(9H)xanthen]-3-one), and M119 (cyclohexanecarboxylic acid [2-(4,5,6-trihydroxy-3-oxo-3H-xanthen-9-yl)-(9CI)]) suppressed citral's inhibition of the response to octanol, indicating that the activation of PI3K by citral was G-protein dependent, consistent with the idea that inhibition acts via the canonical OR. Lilial similarly antagonized the response to isoamyl acetate in other ORNs, indicating the effect generalizes to at least one other odorant pair. The ability of methyl-isoeugenol, limonene, α-pinene, isovaleric acid, and isosafrole to inhibit the response of other ORNs to IBMX (3-isobutyl-1-methylxanthine)/forskolin in a PI3K-dependent manner argues the effect generalizes to yet other structurally dissimilar odorants. Our findings collectively raise the interesting possibility that the OR serves as a molecular logic gate when mammalian ORNs are activated by natural, complex mixtures containing both excitatory and inhibitory odorants.
51 citations
TL;DR: In this article, the authors show that the unsaturated alcohols are formed in higher quantity on samples reduced at 500 degrees C and more notably with Pt/TiO2 catalyst, and that samples prepared by impregnation of the metallic precursor salt in HCl medium and activated at 300 degrees C are the only ones to lead to the formation of isopulegol as byproduct.
Abstract: During citral hydrogenation, the products distribution obtained on Rh/TiO2 and Pt/TiO2 catalysts depends on their preparation and activation protocols: (i) the unsaturated alcohols (the intended products) are formed in higher quantity on samples reduced at 500 degrees C and more notably with Pt/TiO2 catalyst; (ii) samples prepared by impregnation of the metallic precursor salt in HCl medium and activated at 300 degrees C are the only ones to lead to the formation of isopulegol as by-product. On the catalysts activated at 500 degrees C, these results can be explained by the presence of the SMSI effect beneficial to hydrogenate selectively the C=O bond of citral towards unsaturated alcohols.
51 citations
TL;DR: The results show that the investigated enoate reductase is a promising catalyst for the use in asymmetric C═C bond reductions and can be used for the production of enantiomerically pure building blocks, which are difficult to prepare by chemical means.
Abstract: A recombinant enoate reductase from Gluconobacter oxydans was heterologously expressed, purified, characterised and applied in the asymmetric reduction of activated alkenes. In addition to the determination of the kinetic properties, the major focus of this work was to utilise the enzyme in the biotransformation of different interesting compounds such as 3,5,5-trimethyl-2-cyclohexen-1,4-dione (ketoisophorone) and (E/Z)-3,7-dimethyl-2,6-octadienal (citral). The reaction proceeded with excellent stereoselectivities (>99% ee) as well as absolute chemo- and regioselectivity, only the activated C=C bond of citral was reduced by the enoate reductase, while non-activated C=C bond and carbonyl moiety remained untouched. The described strategy can be used for the production of enantiomerically pure building blocks, which are difficult to prepare by chemical means. In general, the results show that the investigated enoate reductase is a promising catalyst for the use in asymmetric C=C bond reductions.
TL;DR: Investigation of the effect of the extracts of various parts of C. citratus (leaves, stems and roots) and citral on the visceral smooth muscle activity of rabbit ileum showed spasmolytic activity and it appeared that they may act as calcium antagonists.
Abstract: Cymbopogon citratus, commonly known as lemongrass, has been shown to have antioxidant, antimicrobial and chemo-protective properties. Citral, a monoterpenoid, is the major constituent of C. citratus that gives off a lemony scent and is postulated to be responsible for most of its actions. In addition, C. citratus has been traditionally used to treat gastrointestinal discomforts, however, the scientific evidence for this is still lacking. Thus, the aim of the present study was to investigate the effect of the extracts of various parts of C. citratus (leaves, stems and roots) and citral on the visceral smooth muscle activity of rabbit ileum. The effect of the test substances were tested on the spontaneous contraction, acetylcholine (ACh)- and KCl-induced contractions. Citral at doses between 0.061 mM to 15.6 mM and the extract of leaves at doses between 0.001 mg/mL to 1 mg/mL significantly reduced the spontaneous, ACh- and KCl-induced ileal contractions. When the ileum was incubated in K(+)-rich-Ca(2+)-free Tyrode's solution, it showed only minute contractions. However, the strength of contraction was increased with the addition of increasing concentrations of CaCl(2). The presence of citral almost abolished the effect of adding CaCl(2), while the leaf extract shifted the calcium concentration-response curve to the right, suggesting a calcium antagonistic effect. These results were similar to that elicited by verapamil, a known calcium channel blocker. In addition, the spasmolytic effect of citral was observed to be reduced by the nitric oxide synthase inhibitor, L-NAME. In conclusion, citral and the leaf extract of C. citratus exhibited spasmolytic activity and it appeared that they may act as calcium antagonists. Furthermore, the relaxant effect of citral, but not that of the leaf extract may be mediated by nitric oxide suggesting the presence of other chemical components in the leaf extract other than citral.
TL;DR: The first-order dependence on hydrogen pressure and near zero order dependence on citral concentration were observed for the initial rate of citral hydrogenation over the Pt-Sn/TiO 2 and Au/TiOs/O 2 thin films as discussed by the authors.
Abstract: The kinetics of the liquid-phase hydrogenation of citral (3,7-dimethyl-2,6-octadienal) on Au/TiO 2 and Pt–Sn/TiO 2 thin films was studied in the temperature range 313–353 K and citral concentrations of 0.25–10.0 mol m −3 . The thin films were deposited onto the inner walls of silica capillaries with internal diameter of 250 μm. First-order dependence on hydrogen pressure and near zero order dependence on citral concentration were observed for the initial rate of citral hydrogenation over the Pt–Sn/TiO 2 and Au/TiO 2 thin films. The Au/TiO 2 catalyst prevents citronellal formation. The highest yield of unsaturated alcohols was obtained on the Pt–Sn/TiO 2 film at a reaction temperature of 343 K, liquid residence time of 30 min and a citral conversion of 99%.
TL;DR: In this article, the performance of these catalysts in the citral hydrogenation was related with the characteristics of the metallic phase, and it was found that the addition of ionic Sn to the Pt catalysts increases the selectivity to double unsaturated alcohols for both catalyst series.
Abstract: The liquid phase citral hydrogenation, using Pt and PtSn catalysts supported on MgAl 2 O 4 and γ-Al 2 O 3 , was studied in a stirred reactor at 70 °C and atmospheric pressure. It was found that the addition of Sn to the Pt catalysts increases the selectivity to double unsaturated alcohols for both catalyst series. Besides, monometallic catalysts hydrogenate the α,β-unsaturation with a high selectivity in absence of cyclization secondary products. The performance of these catalysts in the citral hydrogenation was related with the characteristics of the metallic phase. Results from test reactions – cyclohexane dehydrogenation (CHD) and cyclopentane hydrogenolysis (CPH) – H 2 chemisorption, 2-propanol dehydration, temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS), were used to explain the influence of the support and the Sn loading and postulate the models of the catalytic metallic surface. Results indicated that, a fraction of ionic Sn would be deposited near Pt, thus increasing the polarization of the carbonyl group, and a fraction of metallic Sn could form Pt–Sn alloy phases that would hinder the hydrogenation of the olefinic bonds and would be active to the hydrogenation of the carbonyl group. Both effects contribute to a higher selectivity to unsaturated alcohols in bimetallic PtSn/Al 2 O 3 catalysts than PtSn/MgAl 2 O 4 ones, which display a low alloy formation.
TL;DR: The chemical composition of the essential oil from the rhizome of ginger, collected from Nahan, Himachal Pradesh, India, was determined by gas chromatography and GC-MS and five compounds are reported for the first time in oil of ginger.
Abstract: The chemical composition of the essential oil from the rhizome of ginger (Zingiber officinale Roscoe), collected from Nahan, Himachal Pradesh, India, was determined by gas chromatography and GC-MS. Fifty-one compounds, representing 95.1% of the oil, were identified. The oil was characterized by relatively large amounts of the monoterpenoids 1,8-cineole (10.9%), linalool (4.8%), borneol (5.6%), alpha-terpineol (3.6%), neral (8.1%), geraniol (14.5%), geranial (9.5%), trans-dimethoxy citral (5.0%) and geranyl acetate (6.3%). Five compounds, namely trans-linalool oxide, trans-linalool oxide acetate, (Z)-dimethoxycitral, (E)-dimethoxy citral and epi-zingiberenol are reported for the first time in oil of ginger.
TL;DR: The findings suggest that citral increased energy dissipation (and also reduced lipid accumulation) consequently preventing and ameliorating diet-induced obesity and in the current scenario of increasing prevalence of obesity and diabetes, citral may prove as novel agent in its management.
Abstract: Objectives: Retinaldehyde inhibits adipogenesis, increases metabolic rate, reduces weight gain, and improves tolerance to a glucose load. We assessed the effects of citral - an inhibitor of retinaldehyde dehydrogenase (the primary enzyme metabolizing retinaldehyde), on body weight, glucose tolerance, fasting plasma glucose and insulin levels, metabolic rate, adipocyte size, and morphology in a diet-induced model of obesity. Materials and Methods: Out of the 5 groups of 6-week-old male Sprague-Dawley rats, 4 were maintained on an energy-intense, palatable, diet for a period of - 42 days, while 1 served as the control. After obesity had been induced, 3 groups were treated with daily doses of citral (10, 15, and 20 mg/kg body weight) for a period of 28 days. They were then subjected to metabolic experiments. Body weight, fasting plasma glucose, glucose tolerance to an intraperitoneal glucose load, metabolic rate, and adipocyte size were assessed. Results: Citral-treated groups showed a dose-dependent reduction in body weight gain. They significantly had lower fasting glucose levels, improved glucose tolerance, lower fasting plasma glucose, higher metabolic rate, and smaller adipocytes after drug administration. Conclusion: The findings suggest that citral increased energy dissipation (and also reduced lipid accumulation) consequently preventing and ameliorating diet-induced obesity. In addition it improved insulin sensitivity and glucose tolerance. In the current scenario of increasing prevalence of obesity and diabetes, citral may prove as novel agent in its management.
TL;DR: The results obtained at isothermal temperatures and with single aroma components provide basic information regarding components frequently found in essential oils, which can be used in combination with less extreme thermal treatments to provide energy conservation and improve food quality.
TL;DR: In this paper, the potential of the disaccharide trehalose as carrier for producing spray-dried citral was examined and some physical and sensory characteristics of citral encapsulated in matrices containing either trehaloses or sucrose and maltodextrin (MD) were analysed.
Abstract: Summary
The potential of the disaccharide trehalose as carrier for producing spray-dried citral was examined. Some physical and sensory characteristics of citral encapsulated in matrices containing either trehalose or sucrose and maltodextrin (MD) were analysed. They included water sorption, glass transition temperatures (Tg), nuclear magnetic resonance (NMR) relaxation and citral retention during spray-drying. The glassy state at room temperature (25 °C) was maintained as far as 33% relative humidities (RH) for the spray-dried trehalose formulation and 43% RH for trehalose–MD; however, for sucrose–MD and for sucrose formulations, the glassy state was limited to RHs lower than 33% and 22%, respectively. Sensory evaluation and gas chromatographic analysis indicated that citral retention after spray-drying was similar for matrices containing either trehalose or sucrose. However, trehalose formulations had improved physical stability as compared to sucrose.
TL;DR: The results obtained revealed that the most favorable complex formation governing between citrals in lemongrass oil and CDs were found at a 1:2 mole ratio for all CDs.
Abstract: The complexation between two isomers of citral in lemongrass oil and varying types of cyclodextrins (CDs), α-CD, β-CD, and HP-β-CD, were studied by molecular modeling and physicochemical characterization. The results obtained revealed that the most favorable complex formation governing between citrals in lemongrass oil and CDs were found at a 1:2 mole ratio for all CDs. Complex formation between E-citral and CD was more favorable than between Z-citral and CD. The thermal stability of the inclusion complex was observed compared to the citral in the lemongrass oil. The release time course of citral from the inclusion complex was the diffusion control, and it correlated well with Avrami’s equation. The release rate constants of the E- and Z-citral inclusion complexes at 50 °C, 50% RH were observed at 1.32×10−2 h−1 and 1.43×10−2 h−1 respectively.
Journal Article•
TL;DR: A. triphylla essential oil exhibited an interesting antibacterial activity against Bacillus subtilis and Staphylococcus aureus and No antib bacterial activity was observed against Listeria monocytogenes, Salmonella typhi, Pseudomonas aeruginosa and Escherichia coli.
Abstract: The volatile chemical constituents of Lemon verbena (Aloysia triphylla) were extracted by modified steam distillation method and determined by gas chromatography-mass spectroscopy (GC-MS). Forty-three components were separated and 35 of them were determined qualitatively and quantitatively, which represented about 96.05%. The major component was citral (14.21%) and seven components were identified as main components (more than 4%) i.e., β-caryophyllene (10.71%), 1, 8-cineole (9.1%), Citronellol (8.87%), iso-menthone (6.43%), α-bergamotene (5.33%), menthonol (5.10%) and p-cymene (4.23%). The resulting oil was tested for its radical scavenging activity employing 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Through all concentrations (5, 10 and 15 μL) for DPPH assay moderate radical scavenging activity compared to BHA. A. triphylla essential oil was tested against six Gram-positive and Gram-negative bacteria, three phytopathogenic fungi and pathogenic yeast. A. triphylla essential oil exhibited an interesting antibacterial activity against Bacillus subtilis and Staphylococcus aureus. No antibacterial activity was observed against Listeria monocytogenes, Salmonella typhi, Pseudomonas aeruginosa and Escherichia coli. A. triphylla essential oil partially inhibited the growth of the fungal strains and pathogenic yeast was observed against Phanerochaete chysosporium, Trichoderma reesei and Candida albicans. No antifungal effect was observed against Trichoderma viride.
TL;DR: Global efforts to reduce the level of highly toxic synthetic acaricides in the agricultural environment justify further studies on materials derived from lemon eucalyptus oil, particularly menthol and citronellyl acetate, as potential acar pesticides for the control of acaricide-resistant T. urticae as fumigants with contact action.
Abstract: BACKGROUND: This study was aimed at assessing the fumigant toxicity of 14 essential oil constituents from lemon eucalyptus, Eucalyptus citriodora Hook, and another ten known compounds to females of acaricide-susceptible, chlorfenapyr-resistant, fenpropathrin-resistant, pyridaben-resistant and abamectin-resistant strains of Tetranychus urticae Koch.
RESULTS: Menthol (LC50, 12.9 µg cm−3) was the most toxic compound, followed by citronellyl acetate (16.8 µg cm−3), against the susceptible females. High toxicity was also produced by β-citronellol, citral, geranyl acetate and eugenol (LC50, 21.7–24.6 µg cm−3). The fumigant toxicity of these compounds was almost identical against females from either of the susceptible and resistant strains, indicating that the compounds and acaricides do not share a common mode of action or elicit cross-resistance.
CONCLUSION: Global efforts to reduce the level of highly toxic synthetic acaricides in the agricultural environment justify further studies on materials derived from lemon eucalyptus oil, particularly menthol and citronellyl acetate, as potential acaricides for the control of acaricide-resistant T. urticae as fumigants with contact action. Copyright © 2011 Society of Chemical Industry
TL;DR: In this article, a short-path distillation (SPD) was used to increase the citral concentration in lemongrass essential oil, without adding any extra components to the system, causing minimal thermal impact and reaching high quality for the essential oil extracted at the distillate stream.
Abstract: Short-path distillation (SPD), a special high-tech thermal separation technique operating at high vacuum, was used in order to increase the citral concentration in lemongrass essential oil, without adding any extra components to the system, causing minimal thermal impact and reaching high quality for the essential oil extracted at the distillate stream. Experiments were carried out using a centrifugal molecular distillation unit with an evaporator temperature (EVT) from 60 to 120 °C and a feed flow rate (Q) from 1.5 to 4.5 mL·min–1. Experimental protocols for oil and fat analysis were used to characterize the materials extracted. Results (obtained using GC–MS) showed that bSPD was successful in the separation and purification of essential oil. High-quality essential oil was confirmed because of citral concentration increases from 19.816 mgcitral·mL–1 (initial sample) to 40.963 mgcitral·mL–1 (at 120 °C and 4.5 mL·min–1), reaching a concentration of the bioactive compound (citral) in the distillate stream o...
TL;DR: In this paper, the effect of Sr and some lanthanides (La, Nd, Sm) as promoters of Pt/KL supported catalysts is analyzed in the selective hydrogenation of citral in the liquid phase.
Abstract: The effect of Sr and some lanthanides (La, Nd, Sm) as promoters of Pt/KL supported catalysts is analyzed in the selective hydrogenation of citral in the liquid phase. Characterization of the catalysts by XRD, N2 adsorption, H2 chemisorption, TPD of NH3, XPS and competitive hydrogenation of benzene/toluene mixtures shows that impregnation of KL zeolite with Sr(NO3)2 in aqueous solution, followed by calcination prior to the incorporation of Pt, increases the surface basicity of the zeolite, which hinders the dispersion of Pt and promotes the formation of electron-rich platinum nanoparticles (Ptδ−). Ion exchange of K+ by rare earth cations (La3+, Nd3+ and Sm3+) increases the surface acidity of the zeolite and favors the dispersion of Pt, but with preferential location at the external surface of the zeolite. Furthermore, acidity promotes the formation of electron-deficient metal species (Ptδ+). Catalytic performances for the citral hydrogenation at 323 K and 5 MPa show that strontium addition enhances the hydrogenation activity of Pt, thus favoring the formation of citronellol as main reaction product (S = 80%) and increasing the yield to geraniol and nerol. Lanthanides as countercations diminish the overall hydrogenation activity of Pt/KL catalysts, but improve their selectivity towards unsaturated alcohols. Selectivity towards the reaction products is related to the mode and strength of the electronic interactions of the conjugated unsaturated bonds of citral reactant molecules with the metal surface species Pt0, Ptδ+ or Ptδ− on the zeolite.
TL;DR: The use of botanical compounds such as essential oils has recently become the subject of great interest as a natural means of pest control because of their ovicidal, larvicidal, or adulticidal activity against various insect species including head lice.
Abstract: The use of botanical compounds such as essential oils has recently become the subject of great interest as a natural means of pest control because of their ovicidal, larvicidal, or adulticidal activity against various insect species including head lice. We tested and compared the efficacy of pure oxygenated monoterpenoids that are main ingredients of essential oils of good biological activity. We used pulegone and citral, components of Aloysia citrodora, and geraniol, citronellol, and linalool, components of Geranium sp. oil. We found that citronellol and geraniol showed the highest knockdown and mortality effect (>60%) on adults of both sexes (50:50%) and third-stage nymphs. Pulegone, linalool, and citral showed knockdown percentages between 42 and 55%, and mortality percentages between 47 and 53%. A simple linear regression analysis showed statistically significant relationships between the studied toxic effects and viscosity of the monoterpenoids (p < 0.05), but not with their partition coefficient (log P).
01 Jan 2011
TL;DR: The results evidenced the potential of accession L45 to produce citral, which can be used to improve the quality of "erva-cidreira" raw material in phytotherapy programs in the country or in breeding programs.
Abstract: "Erva-cidreira" [Lippia alba (Mill.) N.E.Brown] is a native species used as a medicinal plant all over Brazil. Citral, a major constituent of L. alba essential oil, is responsible for its sedative activity. The aim of this study was to evaluate the agronomic behavior, content and yield of essential oil and citral in 17 accessions of L. alba from the germplasm bank of University of Brasilia - UnB, Brazil. The experiment was carried out from 02/19/2005 to 03/18/2006, in red latosol, at the Federal District, Brazil. The adopted experimental design was in randomized blocks, with three replicates and three plants per plot. The following parameters were evaluated: leaf area, stem length, fresh mass (leaves and stems) production, dry leaf mass production, essential oil and citral content, estimated yield of essential oil and citral per plant, besides characterization of the essential oil aromatic profile. Accessions L41 (0.75%), L45 (0.66%) and L08 (0.62%) showed the highest essential oil content. Accessions L45 (1.32 g pl-1) presented the highest essential oil yield, followed by L47 (0.73 g pl-1), L41 (0.67 g pl-1), L34 (0.67 g pl-1) and L33 (0.62 g pl-1). Citral content varied from 51.7% (L34) to 75.1% (L09), with an average of 63.6% and predominance of the isomer geranial (36.4%) over neral (27.8%). Accession L45 (0.83 g pl-1) showed the highest citral yield. Thirteen accessions presented the chemotype citral; three, the chemotype citral-limonene, and only one had the chemotype citral-myrcene. The results evidenced the potential of accession L45 to produce citral, which can be used to improve the quality of "erva-cidreira" raw material in phytotherapy programs in the country or in breeding programs.
Journal Article•
TL;DR: Citral was found to be a moderate inhibitor of mammalian alpha-amylase, with an IC50 of 120 μM, and caused also a decrease of alpha-AMylase levels in vivo, and moderate lowering of postprandial glucose, alongside with normalization of blood lipid profile was observed in diabetic rats upon treatment with the compound.
Abstract: Background: As potential anti-diabetic and anti-obesity agents, glycosidase inhibitors are the subject of numerous studies. Among these enzymes, alpha-amylases are of particular interest, and most of their reported inhibitors have so far been natural compounds. Citral is an isoprenoid compound of various essential oils, and based on its alpha-amylase inhibitory effect, was further studied here in an in vivo model of type 1 diabetes. Methods: In vitro effect of the compound was assessed on mammalian alpha-amylase activity with the use of the Bernfeld method. In vivo effect of the compound was studied on streptozotocin-induced diabetic rats (wistar). Non-diabetic and diabetic rats received citral at 2, 8, 16 or 32 mg/kg body weight; the compound was dissolved in grape seed oil. The control groups received grape seed oil alone. Treatment was done for 24 days, after what the animals were sacrificed under light ether anesthesia. Measured parameters included: food and water ingestion and urine volume (daily), blood glucose levels (every two days), cholesterol, triacylglycerol, concentrations, and alpha-amylase levels after 24 days. Results: Citral was found to be a moderate inhibitor of mammalian alpha-amylase, with an IC50 of 120 μM, and caused also a decrease of alpha-amylase levels in vivo. Moderate lowering of postprandial glucose, alongside with normalization of blood lipid profile was observed in diabetic rats upon treatment with the compound. Citral was also found to be able to promote weight loss and to decrease food intake. Conclusion: Citral could be proposed as a possible antihyperlipidemic agent in diabetes and potential therapeutic in obesity, although further studies are needed to establish its complete profile as potential medication.
TL;DR: Pt/ x %Ti-SBA15 catalysts (x corresponding to the wt.% TiO 2 loading in the Ti-SiO 2 composite, in the range 25-60%) were synthesized by titanium precursor grafting in preformed mesoporous silica as discussed by the authors.
TL;DR: Working with microwave-assisted heating, high yields of citronellal were achieved under mild conditions within short reaction times and the influences of the ionic liquid layer were derived from experiments carried out before and after the reactions.
Abstract: The microwave-assisted hydrogenation of citral (3,7-dimethylocta-2,6-dienal) to citronellal with molecular hydrogen as the reducing agent was investigated. Several polar and non-polar solvents were screened and imidazolium-based ionic liquids were applied as modifiers for the palladium-containing porous glass catalysts (Pd/TP). The best results were obtained with N-ethyl-N’-methylimidazolium dicyanamide, N-ethyl-N’-methylimidazolium acetate, or N-ethyl-N’-methylimidazolium trifluoroacetate, which were used to prepare supported catalysts with an ionic liquid layer (SCILL) on Pd/TP by wet-impregnation. The influence of pressure and temperature when using these ionic liquid-containing catalysts, as well as their long-term stabilities, were examined. Working with microwave-assisted heating, high yields of citronellal were achieved under mild conditions within short reaction times. Catalyst characterization was carried out by means of BET measurements, X-ray photoelectron spectroscopy (XPS) and thermo-gravimetric analyses. The influences of the ionic liquid layer were derived from experiments carried out before and after the reactions.
TL;DR: Citral has the best potential for development as a fumigant against twospotted spider mite on agricultural products harvested late in the growing season.
Abstract: Fumigant activity of 34 commercial essential oils was assessed on female adults and eggs of twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) at three temperatures (5, 15, and 25°C) Common thyme, cinnamon, and lemongrass oils were equally effective on twospotted spider mite adults showing 858–100% mortality at 5 and 10 µl/liter air at 25°C At a lower temperature of 15°C, lemongrass and peppermint resulted in ≥90% mortality of adults at 10 µl/liter air Only lemongrass was relatively active at 5 µl/liter air, at 15°C At 5°C, lemongrass and peppermint caused significantly higher adult mortality than controls but only at 10 µl/liter air Common thyme oil showed the highest ovicidal activity at 5 µl/liter air at 25°C Among the main components of common thyme and lemongrass oils, citral was lethal to twospotted spider mite adults at all tested temperatures Carvacrol, thymol, and citral caused the same inhibitory effects on the hatch of twospotted spider mite eggs at 25°C H
TL;DR: In this paper, the authors report characterization of the extracts from the fruits of Litsea cubeba (Lour), which widely distributes in southern China, Japan, and other parts of southeast of Asia.
Abstract: Currently extracts fruits of Litsea cubeba (Lour.) (FLC) is mainly used as natural remedies, perfumery ingredients and food additives. This study reports characterization of the extracts from FLC, which widely distributes in southern China, Japan, and other parts of southeast of Asia. The ethanol extracts of FLC were analyzed by gas chromatography-mass spectrometry (GC-MS), GC-flame ionization detection (GC-FID), and GC-olfactometry (GC-O). A total of 29 compounds were identified and quantified. Among them, the predominant compounds in ethanol extracts of FLC were d-limonene (8.52%), α-citral (26.15%), β-citral (33.16%). It also contains abundant of hydrocarbon monoterpenes, monoterpenes oxide and aliphatic acids and esters. The most frequent descriptors of the ethanol extracts components assessed by GC-O were “citrus”, “lemon”, “sweet”, “spicy”, “pine”, “green”. p-Cymene, thujanol, d-limonene, linalool, caryophyllene, α-citral and β-citral are the most important contributors to the aroma of the extracts.
Key words: Litsea cubeba, aroma, extracts, citral.