Showing papers on "Citral published in 2012"
TL;DR: The objective of the study was to determine the effects of three maturity stages at harvest of lemongrass on essential oil, chemical composition and citral contents, and there were significant effects of maturity stages on essentialOil andcitral contents.
Abstract: The demand for lemongrass (Cymbopogon citratus) is for its high citral content. Early or delayed harvesting of lemongrass affected essential oil and citral content. The objective of the study was to determine the effects of three maturity stages at harvest of lemongrass on essential oil, chemical composition and citral contents. The lemongrass plant was planted using a randomized complete block design with four replications, at the University Agriculture Park, Universiti Putra Malaysia. The plants were harvested at 5.5, 6.5, and 7.5 months after planting. After harvest, the essential oil, chemical composition and citral contents were analysed using gas chromatography-mass spectrometry (GC-MS) analysis. There were significant effects of maturity stages on essential oil and citral contents. Lemongrass harvested at 5.5 and 6.5 months after planting had significantly higher oil contents than those harvested at 7.5 months. A total of 65 compounds were detected from all the three stages of maturity. However, only 13 compounds were present at each of the maturity stage. Among 13 compounds, only 7 compounds (β-myrcene, 3-undecyne, neral, geranial, nerol, geranyl acetate and juniper camphor) had a concentration of greater than 1%. The citral content at 6.5 months after planting was higher by 11.4% than at 5.5 months after planting. The citral content decreased by 5.4% when lemongrass was harvested at 6.5 compared to at 7.5 months after planting. Citral content peaked at 6.7 ± 0.3 months after planting. Thus, maturity stage at harvest influenced essential oil and citral contents of lemongrass. Therefore, lemongrass should be harvested at the appropriate level of maturity in order to achieve high quality essential oil and lower production cost.
Key words: Geranial, neral β-myrcene, hydrodistillation, freeze dry.
151 citations
TL;DR: In repellent bioassays, lemon essential oil, S-(−)-limonene, citral (mixture of neral\geranial) and (+)-β-pinene were the most effective compared with other citrus essential oils and components against adult mosquitoes.
Abstract: Laboratory experiments were conducted to study the bioefficacy against Ae. albopictus of three Citrus essential oils, derived from peels of Citrus sinensis, Citrus limon, and Citrus paradise and of their components. Chiral gas chromatography analysis revealed the dominant occurrence of R-(+)-limonene and (-)-β-pinene in all three essential oils while in the case of lemon oil γ-terpinene, neral, and geranial detected also among other components. The tested Citrus essential oils were toxic against mosquito larvae with LC(50) values ranging from 25.03 to 37.03 mg l(-1). Among citrus essential oils components tested, γ-terpinene was the most toxic (LC(50) = 20.21 mg l(-1)) followed by both enantiomeric forms of limonene (LC(50) = 35.99 and 34.89 mg l(-1), for R-(+)-limonene and S-(-)-limonene, respectively). The delayed toxic effects after exposure of larvae to sublethal (LC(50)) doses were also investigated for citrus essential oils and their major component R-(+)-limonene, indicating a significant reduction of pupal survival. In repellent bioassays, lemon essential oil, S-(-)-limonene, citral (mixture of neral\geranial) and (+)-β-pinene were the most effective compared with other citrus essential oils and components against adult mosquitoes. Repellent bioassays also revealed that limonenes and β-pinenes showed an isomer dependence repellent activity. Finally, according to enantiomeric distribution of limonene and α- and β-pinene, the repellency of lemon essential oil is possibly attributed to the presence of citral.
106 citations
TL;DR: It is proposed that citral was responsible for anti-Leishmania activity of the C. citratus and both may represent a valuable source for therapeutic control of leishmaniasis.
100 citations
TL;DR: Eight substances that are main components of the essential oils from three Mediterranean aromatic plants, previously found active against some phytopathogenic Fungi and Stramenopila, have been tested in vitro against five etiological agents of post-harvest fruit decay.
Abstract: Eight substances that are main components of the essential oils from three Mediterranean aromatic plants (Verbena officinalis, Thymus vulgaris and Origanum vulgare), previously found active against some phytopathogenic Fungi and Stramenopila, have been tested in vitro against five etiological agents of post-harvest fruit decay, Botrytis cinerea, Penicillium italicum, P. expansum, Phytophthora citrophthora and Rhizopus stolonifer. The tested compounds were β-fellandrene, β-pinene, camphene, carvacrol, citral, o-cymene, γ-terpinene and thymol. Citral exhibited a fungicidal action against P. citrophthora; carvacrol and thymol showed a fungistatic activity against P. citrophthora and R. stolonifer. Citral and carvacrol at 250 ppm, and thymol at 150 and 250 ppm stopped the growth of B. cinerea. Moreover, thymol showed fungistatic and fungicidal action against P. italicum. Finally, the mycelium growth of P. expansum was inhibited in the presence of 250 ppm of thymol and carvacrol. These results represent an important step toward the goal to use some essential oils or their components as natural preservatives for fruits and foodstuffs, due to their safety for consumer healthy and positive effect on shelf life extension of agricultural fresh products.
93 citations
TL;DR: The results suggested that the addition of the cationic CS interfacial layer was effective in improving the stability of citral during storage and proved the existence of strong interactions between emulsions and the cATIONic polymer coatings.
Abstract: Multilayer emulsions containing citral were prepared by the layer-by-layer deposition technique based on the electrostatic interaction between negatively charged emulsion droplets and two positively charged biopolymer coatings, chitosan (CS) and e-polylysine (EPL). The optimum concentrations of both CS and EPL were determined through the ζ-potential and particle size measurements and were found to be 1.5 mg/mL for CS and 6 mg/mL for EPL. Quartz crystal microbalance with dissipation monitoring (QCM-D) was conducted to monitor the binding between emulsion droplets and cationic polymers, and our results proved the existence of strong interactions between emulsions and the cationic polymer coatings. The stability of citral and the production of the off-flavor compounds were analyzed by solid-phase microextraction gas chromatography (SPME-GC). The results suggested that the addition of the cationic CS interfacial layer was effective in improving the stability of citral during storage.
54 citations
TL;DR: Essential oils from Colombian plants were characterised by GC–MS, and assayed for anti-quorum sensing activity in bacteria sensor strains, finding promising properties as QS modulators.
50 citations
TL;DR: Ultra-performance liquid chromatography coupled to mass spectrometry (MS) technology has been applied to the analysis of non-volatile migrants from new active packaging materials, revealing the migration of some of the active substances used in the manufacture of active packaging.
Abstract: Ultra-performance liquid chromatography (UPLC) coupled to mass spectrometry (MS) is a useful tool in the analysis of non-volatile compounds, and the use of a quadrupole-time-of-flight (Q-TOF) mass analyzer allows a high sensitivity and accuracy when acquiring full fragment mode, providing a high assurance of correct identification of unknown compounds. In this work, UPLC-Q-TOF-MS technology has been applied to the analysis of non-volatile migrants from new active packaging materials. The materials tested were based on polypropylene (PP), ethylene–vinyl alcohol copolymer (EVOH), and poly(ethylene terephthalate) (PET). The active packaging materials studied were one PP film containing a natural antioxidant, and two PP/EVOH films, two PET/EVOH films and one coextruded PP/EVOH/PP film containing natural antimicrobials. The chemical structure of several compounds was unequivocally identified. The analysis revealed the migration of some of the active substances used in the manufacture of active packaging, such as caffeine (0.07 ± 0.01 μg/g), carvacrol (0.31 ± 0.03 μg/g) and citral (0.20 ± 0.01 μg/g). Unintentionally added substances were also found, such as citral reaction compounds, or citral impurities present in the raw materials.
50 citations
TL;DR: It is suggested that at lower concentrations, citral interferes with cell division by disrupting mitotic micro Tubules and cell plates, and at higher concentrations it inhibits cell elongation by disrupting cortical microtubules.
Abstract: The plant volatile monoterpene citral is a highly active compound with suggested allelopathic traits. Seed germination and seedling development are inhibited in the presence of citral, and it disrupts microtubules in both plant and animal cells in interphase. We addressed the following additional questions: can citral interfere with cell division; what is the relative effect of citral on mitotic microtubules compared to interphase cortical microtubules; what is its effect on newly formed cell plates; and how does it affect the association of microtubules with c-tubulin? In wheat seedlings, citral led to inhibition of root elongation, curvature of newly formed cell walls and deformation of microtubule arrays. Citral’s effect on microtubules was both dose- and time-dependent, with mitotic microtubules appearing to be more sensitive to citral than cortical microtubules. Association of c-tubulin with microtubules was more sensitive to citral than were the microtubules themselves. To reveal the role of disrupted mitotic microtubules in dictating aberrations in cell plates in the presence of citral, we used tobacco BY2 cells expressing GFP-Tua6. Citral disrupted mitotic microtubules, inhibited the cell cycle and increased the frequency of asymmetric cell plates in these cells. The time scale of citral’s effect in BY2 cells suggested a direct influence on cell plates during their formation. Taken together, we suggest that at lower concentrations, citral interferes with cell division by disrupting mitotic microtubules and cell plates, and at higher concentrations it inhibits cell elongation by disrupting cortical microtubules.
47 citations
TL;DR: The findings suggest that the relaxation effect of citral, LE, and RE is endothelium-independent and may be mainly by affecting the intracellular concentration of calcium.
Abstract: Cymbopogon citratus has been shown to have antioxidant, antimicrobial, antispasmodic and chemo-protective properties. Citral, is the major constituent of C. citratus. This study investigated the effects of methanolic extracts of leaves (LE), stems (SE), and roots (RE) of C. citratus and citral on vascular smooth muscle and explored their possible mechanisms of action. The experiment was conducted using isolated tissue preparations, where citral, LE, SE, and RE were added separately into a tissue bath that contained aortic rings, which were pre-contracted with phenylephrine (PE). Citral, LE, and RE exhibited a dose-dependent relaxant effect on the PE-induced contractions. Citral appeared to partially act via NO as its vasorelaxant effect was attenuated by L-NAME. However, the effect of LE may involve prostacyclin as indomethacin reversed the relaxant effect of LE on the PE-induced contraction. Furthermore, citral, LE, and RE abolished the restoration of PE-induced contraction caused by the addition of increasing doses of calcium in both endothelium intact and denuded rings. These findings suggest that the relaxation effect of citral, LE, and RE is endothelium-independent and may be mainly by affecting the intracellular concentration of calcium. Citral may partially act through the NO pathway while a vasodilator prostaglandin may mediate the effect of LE.
46 citations
TL;DR: This paper found that adding an odorant such as caramel makes a sucrose solution taste sweeter, while adding it to citric acid decreased sourness ratings and increased sweetness ratings, while the only difference detected between chefs and controls was in the way that citral affected sourness rating of sucrose solutions.
40 citations
TL;DR: In this paper, a novel technique for the extraction of citral from the leaves of Cymbopogon flexuosus (Steud.) Wats using hydrotropic solutions (sodium salicylate and sodium cumene sulfonate) was investigated.
Abstract: A novel technique for the extraction of citral from the leaves of Cymbopogon flexuosus (Steud.) Wats. using hydrotropic solutions (sodium salicylate and sodium cumene sulfonate) was investigated. The yield of citral was dependent on the concentration of hydrotrope, solid loading, temperature, and size of the plant material. Using the Taguchi method, the extraction was optimized, and both the hydrotropes gave the highest yield of citral at a concentration of 1.75 M, 5% solid loading, a temperature of 30 °C, and a size of 0.25 mm of the plant material. Sodium salicylate gave a better extraction yield of citral than sodium cumene sulfonate. The microscopic analysis of plant leaves provided insight into the extraction mechanism. A kinetic study was carried out to check the extraction efficiency for both the hydrotropes. The hydrotropic solution was successfully recycled. Using hydrotropic extraction, citral could be extracted under normal operating conditions, and the use of traditional organic solvents could...
TL;DR: This poster focuses on the part of the molecule terpene geraniol that is involved in sensitizing compounds via autoxidation and skin metabolism, and the haptens formed in both of these activation pathways.
Abstract: Background. The fragrance terpene geraniol forms sensitizing compounds via autoxidation and skin metabolism. Geranial and neral, the two isomers of citral, are the major haptens formed in both of these activation pathways.
Objectives. To investigate whether testing with oxidized geraniol detects more cases of contact allergy than testing with pure geraniol.
Patients and methods. The pattern of reactions to pure and oxidized geraniol, and metabolites/autoxidation products, was studied to investigate the importance of autoxidation or cutaneous metabolism in contact allergy to geraniol. Pure and oxidized geraniol were tested at 2.0% petrolatum in 2227 and 2179 consecutive patients, respectively. In parallel, geranial, neral and citral were tested in 2152, 1626 and 1055 consecutive patients, respectively.
Results. Pure and oxidized geraniol gave positive patch test reactions in 0.13% and 0.55% of the patients, respectively. Eight of 11 patients with positive patch test reactions to oxidized geraniol also reacted to citral or its components. Relevance for the positive patch test reactions in relation to the patients' dermatitis was found in 11 of 14 cases.
Conclusions. Testing with oxidized geraniol could detect more cases of contact allergy to geraniol. The reaction pattern of the 14 cases presented indicates that both autoxidation and metabolism could be important in sensitization to geraniol.
TL;DR: In this article, a quaternary mixture composed of limonene, γ-terpinene, β-pinene and citral was used to simulate lemon essential oil, and the experimental data were correlated using the NRTL and UNIQUAC models.
TL;DR: Ruthenium catalysts supported on KL zeolite, ZrO 2 and graphite, prepared by incipient wetness impregnation, were characterized by N 2 adsorption, H 2 chemisorption and tested in the selective hydrogenation of citral in the liquid phase, at 5MPa and 323 K.
TL;DR: Citral inhibits the growth of C. albicans and is able to interact with cholesterol, indicating there is some interaction between citral and cholesterol.
Abstract: Context: Candidiasis is a mycosis caused by Candida species, which is of clinical importance due to the increase in resistant yeasts. Candida infection has been a serious health problem due to the inappropriate use of antibiotics. Therefore, it is necessary to study molecules with an antifungal action. Citral is a monoterpene with known pharmacological properties, including antimicrobial action.Objective: The aim of this work was to determine the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of citral and the probable mode of action.Materials and methods: The MIC of citral was determined by the broth microdilution method using Sabouraud dextrose medium. Additionally, the interference of citral in cell wall (sorbitol assay) and the binding of citral to ergosterol and cholesterol were studied, carried out by broth microdilution method.Results: The MIC and MFC of citral were 512 and 1024 µg/mL, respectively. The MIC of amphotericin B was 1 µg/mL. The mechanism of action di...
TL;DR: The role of irradiated sodium alginate (ISA) as plant growth promoter and in essential oil production was studied in lemongrass, which is a major source of the natural citral.
TL;DR: The crude ethanol extract and fractions from citral chemotype showed antinociceptive and anti-inflammatory effects.
Abstract: Preparations from Pimenta pseudocaryophyllus (Gomes) L.R. Landrum (Myrtaceae) have been widely used in Brazilian folk medicine. This study aims to evaluate the antimicrobial activity of the crude ethanol extracts, fractions, semipurified substances, and essential oils obtained from leaves of two chemotypes of P. pseudocaryophyllus and to perform the antinociceptive and anti-inflammatory screening. The ethanol extracts were purified by column chromatography and main compounds were spectrally characterised (1D and 2D 1H and 13C NMR). The essential oils constituents were identified by GC/MS. The broth microdilution method was used for testing the antimicrobial activity. The abdominal contortions induced by acetic acid and the ear oedema induced by croton oil were used for screening of antinociceptive and anti-inflammatory activities, respectively. The phytochemical analysis resulted in the isolation of pentacyclic triterpenes, flavonoids, and phenol acids. The oleanolic acid showed the best profile of antibacterial activity for Gram-positive bacteria (), followed by the essential oil of the citral chemotype (). Among the semipurified substances, Ppm5, which contained gallic acid, was the most active for Candida spp. () and Cryptococcus spp. (). The crude ethanol extract and fractions from citral chemotype showed antinociceptive and anti-inflammatory effects.
TL;DR: In this article, the antioxidant activity and free radical scavenging potential of Litsea cubeba essential oil (LCEO) were evaluated from different points of view and compared with citral, a major component in LCEO, ascorbic acid (Vc) and synthetic antioxidants including butylated hydroxytoluene (BHT) and propyl gallate (PG).
Abstract: The antioxidant activity and free radical scavenging potential of Litsea cubeba essential oil (LCEO) were evaluated from different points of view and compared with citral, a major component in LCEO, ascorbic acid (Vc) and synthetic antioxidants including butylated hydroxytoluene (BHT) and propyl gallate (PG). The results revealed that LCEO has notable antioxidant activity. The order of hydroxyl radical scavenging activity was LCEO >BHT > citral > PG >Vc. Their half maximal inhibitory concentration (IC50) values of hydroxyl radical scavenging activity were 0.19, 0.28, 0.50, 0.79 and 1.07 mg/mL, respectively, and IC50 values of scavenging superoxide were 0.45, 0.64, 0.67, 1.08 and 0.51 mg/mL, respectively. Furthermore, the peroxidation of linoleic acid was significantly suppressed by the addition of LCEO. The order of activity was BHT >Vc >LCEO >citral >PG. Chemical composition of LCEO was identified by GC and GC-MS, and major components in the oil were limonene (26.25 %), followed by α-citral (25....
TL;DR: It is demonstrated that colony diameter exhibited a constant increase with time (zero order kinetics) for all antimicrobials evaluated, and potassium sorbate, cineole, anethol and guaiacol were least effective.
Abstract: Effect of water activity (aw, 0.99), pH (4.5) and their interaction on the growth inhibition of Aspergillus parasiticus was studied on potato dextrose agar (PDA) using various antimicrobial agents (citral, carvacrol, eugenol, cineole, thymol guaiacol, vanillin, anethol, potassium sorbate and sorbic acid). The results demonstrate that colony diameter (mm) exhibited a constant increase with time (zero order kinetics) for all antimicrobials evaluated. Eugenol and sorbic acid inhibited the test fungi at 300 and 600 ppm, respectively. Radial growth rate (RGR) of A. parasiticus was significantly (p < 0.05) different among different antimicrobials as well as the concentrations tested. However, this difference was not observed with higher concentration of citral, eugenol, vanillin and sorbic acid. Among the antimicrobials evaluated potassium sorbate, cineole, anethol and guaiacol were least effective. Thymol, eugenol and carvacrol were more effective in inhibiting A. parasiticus even with low concentration (150 ppm) as their mean RGR was zero even after 20 days of incubation (pH 4.5).
TL;DR: ActiveActive and selective bifunctional Me(Ir, Pd)/beta zeolite and doped nanoscopic hydroxylated fluorides (0.1 % Pd (or Pt)/AlF3) catalysts were developed for the one-pot synthesis of menthols from citral as mentioned in this paper.
Abstract: Active and selective bifunctional Me(Ir, Pd)/beta zeolite and doped nanoscopic hydroxylated fluorides (0.1 % Pd (or Pt)/AlF3) catalysts were developed for the one-pot synthesis of menthols from citral. In the case of fluoride catalysts, the strong electron-withdrawing effect of the dominating fluoride environment depletes the metal surface from electrons and hence, favours the hydrogenation of the C=C bond to citronellal on both Pd and Pt-based catalysts.
TL;DR: Citral is a lemon scented acyclic monoterpene aldehyde which consists of a racemic mixture of two isomers geranial (trans-citral or citral A) and neral (cis- citral or Citral B) as discussed by the authors.
Abstract: Citral is a lemon scented acyclic monoterpene aldehyde consists of a racemic mixture of two isomers geranial (trans-citral or citral A) and neral (cis-citral or citral B). It is most important component of essential oils of Cymbopogon species mainly, East Indian (Cymbopogon flexuosus) and West Indian (C. citratus) lemongrass. It is also present as major component in other plant species particularly, citrus fruits. Citral imparts a characteristic lemon like aroma to the essential oils of lemongrass. Citral possesses many significant bioactivities such as, antimicrobial, anti-inflammatory, antiparasitic, allelopathic and mosquito repellent. Citral is most valuable monoterpene in flavors, fragrances, cosmetics, perfumery and pharmaceuticals. It is used for the synthesis of vitamin A and β-ionones and other specialty chemicals. A growing number of reports published on bioactivities of citral and citral rich essential oils have reflected their rapidly increasing medicinal and pharmacological significa...
Journal Article•
TL;DR: Results suggested that essential oil of L. citriodora could be used as a potential control agent against stored-product insects.
Abstract: Essential oil extracted from the leaves of Lemon verbena, Lippia citriodora Kunth (Verbenaceae) was tested for fumigant toxicity in the laboratory against two stored-product insects Tribolium confusum Jacquelin du Val and Callosobruchus maculatus (F.). The chemical composition of the isolated oil was examined by GC-MS. The major compounds were citral (11.3%), limonene (10.6%), neral (7.9%), 4-phenyl undecan-4-ol (7.7%), α- curcumene (6.5%), α-cedrol (4.5%) and caryophyllene oxide (4.5%). Furthermore, lesser amounts of the other components include carveol (3.7%), linalool (3.5%), α-pinene (3.2%), caryophyllene (2.8%) and geranyl acetat (1.8%) were existed in the essential oil. In the fumigant toxicity set at 27 ± 1 °C and 65 ± 5% R. H., darkness condition and 24 h exposure time, considerable differences in mortality of insect to essential oil vapor were observed. C. maculatus (LC 50 = 10.2 µl/l air) was significantly more susceptible than T. confusum (LC50 = 497.8 µl/l air). These results suggested that essential oil of L. citriodora could be used as a potential control agent against stored-product insects.
TL;DR: In this article, two new amines were synthesized from 2-aminoadamantane and the available monoterpenoid aldehydes citral and (−)-myrtenal.
Abstract: Two new amines were synthesized from 2-aminoadamantane and the available monoterpenoid aldehydes citral and (–)-myrtenal. It was established that the synthesized amines possessed anxiolytic activity.
TL;DR: In this article, a Ru/AlO(OH) catalyst was tested in the selective hydrogenation of citral, and the results showed that the combination of Ru and water improved the catalyst activity and its selectivity to geraniol and nerol.
Abstract: A Ru/AlO(OH) catalyst was prepared by co-precipitation and characterised by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), thermo-gravimetry (TG), and Fourier transform infrared spectroscopy (FT-IR). Its catalytic performance was tested in the selective hydrogenation of citral. The results showed that the combination of Ru/AlO(OH) and water obviously improved the catalyst activity and its selectivity to geraniol and nerol. Introducing organic additives increased the hydrophilicity of metal particles, which favoured the adsorption of the citral C O bond over the adsorption of the conjugated C C bond, improving the selectivity to and inhibiting the further hydrogenation of geraniol and nerol. The maximum yield of geraniol and nerol (81%) was achieved in water with ethylenediamine as an additive.
TL;DR: A combination of enantiopure 2-diarylmethylpyrrolidines and heterogeneous Pd/BaSO(4) is an efficient catalytic system for the asymmetric hydrogenation of citral and citronellal is obtained with high enantioselectivity.
TL;DR: In this paper, citral (3,7-dimethyl-2,6-octadienal) was carried out in a batch reactor at atmospheric hydrogen pressure and 70°C over Sibunit (mesoporous carbon) supported iridium catalysts with different metal loadings.
Abstract: Hydrogenation of citral (3,7-dimethyl-2,6-octadienal) was carried out in a batch reactor at atmospheric hydrogen pressure and 70 °C over Sibunit (mesoporous carbon) supported iridium catalysts with different metal loadings. The major products were isopropyl ethers of geraniol and nerol (2-propanol was used as solvent), but also geraniol, nerol, citronellal di-isopropyl acetal and citronellal were formed. The metal particle size was determined by CO-chemisorption and varied from 2 to 6 nm. The turnover frequency for hydrogenation reactions increased with the metal particle size. Turnover frequency of hydrogenation reactions as a function of particle size.
Journal Article•
TL;DR: In this article, the authors used FT-IR in comparison with correlation charts and GC-MS for quantification of various chemical constituents of the essential oil extracted from lemon grass grown in Thika, Kiambu County.
Abstract: Citral is present in the oils of several plants, including lemon myrtle (90-98%), Litsea citrata (Blume.) (90%), Litsea cubeba (Louv.) (70-85%), lemongrass Cymbopogon Citratus (stapf) (65-85%), lemon tea-tree (70-80%), Ocimum gratissimum (L) (66.5%), Lindera citriodora (Siebold and Zucc) (about 65%), Calypranthes parriculata (about 62%), petit grain (36%), lemon verbena (30-35%), lemon ironbark (26%), lemon balm (11%), lime (6-9%), lemon (2-5%), and orange . Citral, present in lemon grass, is used as a flavor and for fortifying lemon oil. This study involved isolation of essential oil from samples of lemon grass grown in Thika, Kiambu County, using hydro distillation and in comparison with correlation charts, functional groups present determined using FT-IR in the fingerprint region. The results obtained from hydro distillation indicated that the percentage yield of oil extracted is higher on dried leaf samples as compared to freshly cut leaves. The spectra obtained from GC-MS was used for relative quantification of various chemical constituents of the oil. Key words : correlation charts, functional groups, FT-IR, GC-MS,
TL;DR: In this paper, a supported ionic liquid catalysts (SILCAs) with various inorganic alkaline modifiers (e.g., potassium hydroxide) were applied in citral hydrogenation reactions.
TL;DR: Essential oil vapor release, monitored in real-time with Atmospheric Pressure Chemical Ionization – MS (APCI-MS), showed differences in the vapor release profile of limonene, β-pinene and linalool over 24 hours, while Solid Phase Micro-extraction (SPME) GC-MS demonstrated changes in composition of the vapor at 35°C.
Abstract: The anti-bacterial components of a citrus essential oil vapor were identified as linalool, citral and beta-pinene using a bioautography method and quantified by GC-MS. Essential oil vapor release, monitored in real-time with Atmospheric Pressure Chemical Ionization - MS (APCI-MS), showed differences in the vapor release profile oflimonene, beta-pinene and linalool over 24 hours, while Solid Phase Micro-extraction (SPME) GC-MS demonstrated changes in composition of the vapor at 35 degrees C. Fourteen isolates were tested in vitro for their susceptibility to the EO vapor and to linalool, citral and beta-pinene vapors, both separately and in a mixture containing the three components in the amounts at which they occur in the EO vapor. All eleven Gram-positive strains tested were susceptible to the EO vapor, linalool, citral and beta-pinene vapors separately and the mixture with zones of inhibition of 4.34 cm, 5.32 cm, 5.58 cm, 4.86 cm and 4.68 cm, respectively. Of the three Gram-negative strains tested, Pseudomonas aeruginosa 10145 was resistant to all the vapors. When bacteria inoculated onto stainless steel surfaces were exposed to either the EO vapor or a linalool/citral/beta-pinene vapor mixture there was no significant difference in reduction for the Gram-positive isolates, while the Gram-negative isolates were resistant to both EO vapor and the linalool/citral/beta-pinene mixture.
TL;DR: In this article, the reactivity and selectivity differences between the prepared catalysts have been explained considering that the deposition of colloids prepared in basic media at high pressures of hydrogen occurs preferentially as iridium oxide or gold complexes.
Abstract: The hydrogenation of citral over Au, Ir–Au and Ir catalysts prepared from colloids using as supports TiO2 and Nb2O5 has been studied. The samples were characterized by N2 adsorption at 77 K, transmission electron microscopy and temperature programmed reduction. The reactivity and selectivity differences between the prepared catalysts have been explained considering that the deposition of colloids prepared in basic media at high pressures of hydrogen occurs preferentially as iridium oxide or gold complexes, similarly to classical methods of preparation (wetness impregnation and deposition–precipitation). In this sense, the catalytic behavior of supported colloids is similar to these methods without the reduction process. This was corroborated when the solids were reduced at 773 K, which leads to catalysts active and highly selective to the hydrogenation of the carbonyl bond.