Academic literature on the topic 'Citronellyl formate'

Volatile organic compounds (VOCs) from leaves of geranium (Pelargonium graveolens L’ Herit) were extracted by dynamic headspace using Porapak Q (HSD-P) as adsorbent and peat, a novel adsorbent in the extraction of plant volatiles, analyzed by gas chromatography–mass spectrometry (GC/MS) and gas chromatography–flame ionization (GC/FID), and the results were compared with those obtained by hydrodistillation (HD). The yield volatiles changed with the extraction method. HD was more efficient for extracting linalool (11.19%) and citronellyl formate (9.41%). Citronellol (28.06%), geraniol (38.26%) and 6,9-guaiadiene (9.55%) and geranyl tiglate (8.21%) were the major components identified by dynamic headspace using peat (HSD-T), while citronellol (16.88%), geraniol (13.63%), 6,9-guaiadiene (16.98%) and citronellyl formate (6.95%) were identified by dynamic headspace using Porapak Q (HSD-P). Furthermore, this work showed, for the first time, that in natura peat is useful to extract VOCs from leaves of geranium.

Pot experiments were conducted to investigate the effects of irrigation frequency and withholding irrigation during the week before harvesting on rose-scented geranium herbage yield and essential oil yield and composition. A factorial experiment with three irrigation frequencies (twice a day, once a day, and every second day) and two growth media (silica sand and sandy clay soil) were conducted in a tunnel. One week before harvest, irrigation was withheld for half of the pots in each treatment combination. In a glasshouse, sandy clay soil was used as growing medium, and five irrigation frequencies (everyday, everyday with 1-week irrigation withholding period, every second day, every third day, and every fourth day irrigation to pot capacity) were applied as treatments. Results showed that essential oil content (percent oil on fresh herbage weight basis) increased as the irrigation frequency decreased. Both herbage yield and essential oil yield positively responded to frequent irrigation. Thus, higher herbage and essential oil yields were obtained from the highest irrigation frequency. A 1-week stress period significantly increased total essential oil yield as well as oil content per fresh herbage weight. The results highlighted that conditions of high soil water availability followed by brief water stress just before harvesting would maximize rose-scented geranium essential oil yield. Citronellol and citronellyl formate tended to increase with an increase in the stress level, but the reverse was true for geraniol and geranyl formate. Other major essential oil components were unaffected by water stress.

Rose-scented geranium ( Pelargonium spp.), which is highly valued for its essential oil, is exclusively propagated vegetatively. Hence no genetic improvement work is possible through conventional breeding. Somaclonal variation was generated with and without in vitro mutagenesis using N-nitroso- N-methyl urea (NMU) in an Indian cultivar ‘Bourbon’, and a clone ‘Narmada’. A somaclonal variant (N75) with a moderately high content of isomenthone in its essential oil was isolated from somaclones generated after treatment of internodal explants of clone, ‘Narmada’ with 0.25 mM NMU for 1 h. The contents of isomenthone in its essential oil were 26% and 35%, respectively, in SC2/VM2 and SC3/VM3 generations (second and third vegetative generations, respectively, after in vitro mutagen treatment) as compared with 0.7% and 0.3%, respectively, in the parental clone, ‘Narmada’. The contents of alcohols and their esters (linalool, citronellol, geraniol, citronellyl formate and geranyl formate) in the essential oil of N75 in SC2/VM2 and SC3/VM3 generations were 49% and 35%, respectively, as compared with 69% and 63%, respectively, in the parental clone, ‘Narmada’. This is the first report on a chemovariant of rose-scented geranium with a moderately high content of isomenthone. All earlier reported isomenthone-rich variants of rose-scented geranium had quite high contents of isomenthone (64-71%) in their essential oils. The probable modes of origin of this somaclonal variant, its parental clone ‘Narmada’ (with very low content of isomenthone) and four earlier reported isomenthone-rich variants of Indian cultivars of geranium are discussed.

Ledum palustre is an important perfume plant in northeast China, and widely distributed at Changbai mountain of Jilin province. The components and contents of essential oils in Ledumpalustre were highly correlated with their growth environment. By using GC-MS, about 32 compounds were identified from Ledumpalustre essential oils of Changbai mountain. The chemical components were L-bornyl acetate (20.2%), 1,2,3,4-tetramethyl-benzene (16.5%), (−)-myrtenal (4.4%), terpinen-4-ol (4.3%), 2,6-dimethyl-2,6-octadiene (3.8%), trans-pinocarveol (3.7%), L(-)-borneol (3.0%), geranyl acetate (2.8%), (+)-aromandendrene (2.3%), ledol (1.7%), sabenene (1.6%), β-pinene (1.4%), camphene (1.1%), caryophyllene oxide (1.1%), and citronellyl formate (0.5%), which indicate the application of Ledumpalustre essential oils from Changbai mountain should be different from other areas.

<em>Pelargonium graveolens</em> L’Hér. is an important aromatic and medicinal plant, which is famous for its essential oils (EOS).The aim of this study was to evaluate the effects of UV-B on growth factors, essential oils components, antioxidant activity of essential oils and antioxidant enzymes activity, carbohydrate content, leaf pigments and total protein. Cuttings from potted plants were exposed to 0, 0.12, 0.26, and 0.38 W m-2 of UV-B radiation. The antioxidant enzyme activity, carbohydrate content and protein and pigments contents were measured by spectrophotometric methods. The composition of EOS was analyzed by GC-MS. The antioxidant activity of the EOS was analyzed by free radical scavenging activity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH). Results demonstrated that the leaves’ fresh and dry mass, plant height, number of leaves, and the content of chlorophyll, protein and total carbohydrates were significantly (P ≤ 0.05) decreased, when plants were subjected to increased intensity of UV radiation. In contrast, the content of carotenoids and antioxidant enzymes activities increased. The chemical composition of EOS indicated that the main components in all treated plants were citronellol, geraniol, and citronellyl formate. The antioxidant activity of the essential oils increased with increasing UV-B radiation. The maximum and minimum IC50 values of essential oils were obtained in control plants and plants under 0.38 W m-2 UV-B radiation, respectively.

The volatile constituents of the essential oil of local Pelargonium graveolens growing in Egypt was investigated by gas chromatography–mass spectrometry (GC–MS), and the main constituents were citronellol (27.67%), cis-Menthone (10.23%), linalool (10.05%), eudesmol (9.40%), geraniol formate 6.87%, and rose oxide (5.77%), which represent the major components in the obtained GC total ion chromatogram. The structural determination of the main constitutes based on their electron ionization mass spectra have been investigated. The MS of these compounds are absolutely identical in mass values of peaks of fragment ions, where their relative intensities have minor differences. In the spectra of all studied compounds, the observed characteristic ions were [M-H2O]+ and [M-CH3]+. The latter has a structure with m/z 69, 83. Different quantum parameters were obtained using Modified Neglect of Diatomic Overlap (MNDO) semi-empirical method as total energy, binding energy, heat of formations, ionization energy, the energy of highest occupied molecular orbital (HOMO), the energy of the lowest unoccupied molecular orbital (LUMO), energy gap Δ, and dipole moment. The antibacterial and antifungal activities of P. graveolens essential oil and identified compounds were tested against wide collection of organisms. The individual identified compounds in the essential oil—citronellol, cis-Menthone, and linalool (except eudesmol)—showed comparable activity to antibiotics. The most active isolated compound was the citronellol and the lowest MIC was found against E. coli. The essential oil showed high antifungal effects and this activity was attributed to cis-Menthone, eudesmol, and citronellol (excluding linalool). cis-Menthone was the most active compound against selected fungi followed by the eudesmol The study recommends local P. graveolens and identified active compounds for further applications in the pharmaceutical industries.

Introducing effective irrigation management in arid and semi-arid regions, like most areas of South Africa, is an indispensable way of maximising crop yield and enhancing productivity of scarce freshwater resources. Holistic improvements in agricultural water management could be realised through integrating the knowledge of crop-specific water requirements. In order to develop effective irrigation schedules for rose-scented geranium (Pelargonium capitatum x P. radens), greenhouse and field experiments were conducted at the Hatfield Experimental Farm of the University of Pretoria, Pretoria, South Africa, from 28 October 2004 to 2006. Results from 20, 40, 60 and 80% maximum allowable depletion (MAD) levels of the plant available soil water (ASW) indicated that plant roots extracted most of the soil water from the top 40 cm soil layer, independent of the treatment. Both essential oil yield and fresh herbage mass responded positively to high soil water content. Increasing the MAD level to 60% and higher resulted in a significant reduction in herbage mass and essential oil yields. An increase in the degree of water stress apparently increased the essential oil concentration (percentage oil on fresh herbage mass basis), but its contribution to total essential oil yield (kg/ha oil) was limited. There was no significant relationship between MAD level and essential oil composition. For water saving without a significant reduction in essential oil yield of rose-scented geranium, a MAD of 40% of ASW is proposed. Response of rose-scented geranium to a one-month irrigation withholding period in the second or third month of regrowth cycles showed that herbage mass and oil yield were positively related. Herbage yield was significantly reduced when the water stress period was imposed during the third or fourth month of regrowth. A remarkable essential oil yield loss was observed only when the plants were stressed during the fourth month of regrowth. Essential oil content (% oil on fresh herbage mass basis) was higher in stressed plants, especially when stressed late, but oil yield dropped due to lower herbage mass. The relationship between essential oil composition and irrigation treatments was not consistent. Water-use efficiency was not significantly affected by withholding irrigation in the second or in the third month of regrowth. With a marginal oil yield loss, about 330 to 460 m3 of water per hectare per regrowth cycle could be saved by withholding irrigation during the third month of regrowth. The overall results highlighted that in water-scarce regions withholding irrigation during either the second or the third month of regrowth in rose-scented geranium could save water that could be used by other sectors of society. In greenhouse pot experiments, rose-scented geranium was grown under different irrigation frequencies, in two growth media. Irrigation was withheld on 50% of the plants (in each plot) for the week prior to harvesting. Herbage and essential oil yields were better in the sandy clay soil than in silica sand. Essential oil content (% oil on fresh herbage mass basis) apparently increased with a decrease in irrigation frequency. Both herbage and total essential oil yields positively responded to frequent irrigation. A one-week stress period prior to harvesting significantly increased essential oil content and total essential oil yield. Hence, the highest essential oil yield was obtained from a combination of high irrigation frequency and a one-week irrigation-withholding period. In the irrigation frequency treatments, citronellol and citronellyl formate contents tended to increase with an increase in the stress level, but the reverse was true for geraniol and geranyl formate. Leaf physiological data were recorded during the terminal one-week water stress in the glasshouse pot trial. Upon rewatering, stomatal conductance (Gs) and transpiration rate (Rt) were significantly lower in the less often irrigated than in the more often irrigated treatments, while leaf water potential (yw) and relative water content (RWC) were the same for all plants, indicating that water stress had an after-effect on Gs and Rt. At the end of the stress period, Gs, Rt, yw and RWC were lower in the plants from the more often irrigated than from the less often irrigated treatments. Irrespective of irrigation treatment, one type of non-glandular and two types (different in shape and size) of glandular trichomes were observed. In water stressed-conditions, stomata and trichome densities increased, while the total number of stomata and trichomes per leaf appeared to remain more or less the same. Water stress conditions resulted in stomatal closure.
Thesis (PhD)--University of Pretoria, 2009.
Plant Production and Soil Science
unrestricted

(-)-4-Hydroxydictyolactone 3, representative of the cyclononene xenicanes isolated from the Dictyotacae algae, readily isomerizes thermally to the more stable ( Z )- 6,7-isomer. Attempts to directly form this strained ring system appeared to be fraught with difficulty. David R. Williams of Indiana University envisoned (J. Am. Chem. Soc. 2009, 131, 9038) that use of Suzuki coupling might ameliorate some of the strain, since at the point of commitment to bond formation, the Pd center would be included in the forming ring. This analysis led specifically to the trans ether 1, as cyclization of the trans ether appeared likely to be more facile than would cyclization of the alternative cis diastereomer. The first challenge was the assembly of the array the four contiguous alkylated stereogenic centers of 1. To this end, the Z secondary ester 7 was prepared from the acetonide 4 , available from mannitol, and ( R )-(+)-citronellic acid, prepared by oxidation of the commercial aldehyde. Addition of 7 to LDA led to decomposition, but inverse addition of LDA to a mixture of the ester, TMSCl, and Et3 N smoothly delivered the ketene silyl acetal. On warming, Ireland-Claisen rearrangement of the ketene silyl acetal led to the acid 8 with remarkable diastereocontrol. The last alkylated stereogenic center of 1 was installed by reductive cyclization of the formate ester 9. Again, the cyclization proceeded with remarkable diastererocontrol. Although the intramolecular reaction of in situ prepared allyl metals is well precedented, the addition to a formate ester had not previously been reported. Although 11 appears to be ready for the long-awaited Suzuki coupling, in fact the TIPS protecting group substantially slowed hydroboration. The free alcohol/methyl acetal was the best substrate for hydroboration, but the free alcohol entered into other side reactions. After extensive experimentation, a happy medium was found with the methyl acetal/TBS ether 1. Selenylation of the lactone 12 followed by oxidative elimination of the selenide delivered the expected Z alkene. Removal of the silyl protecting group had to precede introduction of the second alkene, as the product 3 deteriorated rapidly on exposure to the alkaline conditions of TBAF cleavage.