Isolation and Identification of the Constituents of Volatiles of Flowers of Chloranthus spieatus (Tunb.) Makino

The headspace volatiles of the flowers of Chloranthus spicatus (Tunb.) Makino were trapped by a modified circulation adsorption method and were analyzed by GC/MS techniques after desorption by solvent. The componends were identified by mass spectral and temperature-programmed retention index data on dual glass capillary columns (OV-101 and PEG-20 M). 32 compounds have been identified from the volatiles, including 11 monoterpenes, 11 sesquiterpenes, and 7 oxygen-containing compounds.The major consitituents are cis-methyl jasmonatecis-β-ocimene, and β-pinene.     

Functional evolution of biosynthetic enzymes that produce plant volatiles*

Plants synthesize volatile compounds to attract pollinators. The volatiles emitted by flowers are often complex mixtures of organic compounds; pollinators are capable of distinctly recognizing different volatile compounds. Plants also produce volatile compounds to protect themselves against herbivores and pathogens. Some of the volatile compounds produced in floral and vegetative tissues are toxic to insects and microbes. To adapt changes in the environment, plants have evolved the ability to synthesize a unique set of volatiles. Intensive studies have identified and characterized the enzymes responsible for the formation of plant volatiles. In particular, many biosynthetic genes have been isolated and their enzymatic functions have been proposed. This review describes how plants have evolved the biosynthetic pathways leading to the formation of green leaf volatiles and phenylpropene volatiles.     

Studies on the Chemical Composition of the Head Space and Essential Oil of Fresh Flower of Ku-Shui rose (Rosa setate X R. rugosa)

The chemical composition of the head space and essential oil of fresh flowers of KU-Shui rose, which were collected by adsorption with Paropark Q (60–80 mesh) and steam distillation-extraction respectively, have been identified both by capillary gas chromatography/mass spectrometry and the Kovats Index of the components. From the head space, 63 compounds have been identified, among which 27 compounds were not present or found only in trace amount in the essential oil. From the essential oil, 79 compounds have been identified, among which 55 compounds have not been found in this flower previously.     

Comparative analysis of the volatiles from flowers and leaves of three Gentiana species

The volatiles from fresh flowers and leaves of Gentiana lutea L., Gentiana punctata L. (yellow Gentiana spp.) and Gentiana asclepiadea L. (Gentianaceae Juss.) were analyzed by GC/MS and 81 compounds identified. The samples studied showed differences in the volatile profiles of flowers and leaves among the species. In the flower-oils straight chain saturated aliphatic hydrocarbons were dominant along with low concentrations of branched saturated aliphatic hydrocarbons and alkylated benzenes. These compounds were not present in the flowers of G. lutea and G. punctata and in the leaves of G. lutea. The branched saturated aliphatic hydrocarbons were the main constituents of the leaf-oil from G. ascleapidea. Terpenes were found in all flower-oils and in the leaf oil from G. punctata. Some of the identified compounds might have allelopathic activity. The results obtained confirm the accepted taxonomical scheme of the genus Gentiana and are also in agreement with the evolutionary less advanced position of the yellow species of Gentiana.     

Floral volatile profile in Pleurothallidinae,an orchid subtribe pollinated by flies: ecological and phylogenetic considerations

The Pleurothallidinae are recognized as the largest orchid group pollinated by Diptera. This subtribe has been focus of ongoing phylogenetic studies, in which the floral biology and mating systems of their representatives have been recently assessed and some synapomorphies pointed out, all of them regarding features or processes occurring in flowers. Data about the flower volatiles are still scarce, although it may offer valuable information about the floral biology of this subtribe. Here, we collected and analyzed the volatiles emitted from flowers at anthesis. We selected seven Brazilian species representing both late and early-divergent clades of Pleurothallidinae aiming to describe the chemical profile of flower volatiles and relate the identified compounds to the reproductive biology of the selected species. The outstanding feature regarding the floral scent profile is the ubiquitous occurrence in remarkable concentrations of alkanes, a situation not found in Laellinae, a closed subtribe of Pleurothallidinae. We also present a discussion concerning the ecological aspects of the flower volatiles and their pollinators.     

Volatiles in Different Floral Organs, and Effect of Floral Characteristics on Yield of Extract fromBoronia megastigma(Nees)

The relative amounts of volatile compounds in the extract andheadspace from each floral organ were assessed in order to identifythe main organs for accumulation and emission. The mass of flowers/organs,the number/density of oil glands and yield of volatiles wereexamined for their relationship with extract yield, in clonaland non-clonal plants. Boronia flowers were divided into componentorgans and the solvent extractable product and headspace aboveeach organ type was quantified. The petals comprised 50% ofthe weight of the flowers, and the stigma 20%; however, thestigma contributed 70% of the total volatile compounds to extractfrom the whole flower. Proportionately more ß-iononeand dodecyl acetate were emitted from the stigma and anthersthan were contained in the extract, compared with other volatiles.The sexual organs are morphologically equipped for emissionof volatiles to attract pollinators. Between non-clonal plants, there was a lower coefficient ofvariation for extract yield than for values relating to extractcomposition, indicating that the former is more heritable thanthe latter. Variation between clonal plants was reduced comparedwith variation between non-clonal plants. The environment modifiesyield and quality of extract in clonal plants, indicating thatboth have relatively low heritability. No significant relationshipsbetween any floral characteristics and extract yield were found.Biosynthetic potential to accumulate extract is therefore ofprime importance, and the effect of environment on this potentialshould be the subject of future work. Boronia megastigma; brown boronia; Rutaceae; essential oils; flower; stigma; oil gland; ß-ionone     

Analysis of the volatile components of five Turkish Rhododendron species by headspace solid-phase microextraction and GC-MS (HS-SPME-GC-MS)

Volatile constituents of various solvent extracts (n-hexane, CH2Cl2, H2O) of 15 different organs (leaves, flowers, fruits) of five Rhododendron species (Ericaceae) growing in Turkey were trapped with headspace solid-phase microextraction (HS-SPME) technique and analyzed by GC-MS. A total of 200 compounds were detected and identified from organic extracts, while the water extracts contained only traces of few volatiles. The CH2Cl2 extract of the R. luteum flowers was found to exhibit the most diverse composition: 34 compounds were identified, with benzyl alcohol (16.6%), limonene (14.6%) and p-cymene (8.4%) being the major compounds. The CH2Cl2-solubles of R. x sochadzeae leaves contained only phenyl ethyl alcohol. This study indicated appreciable intra-specific variations in volatile compositions within the genus. Different anatomical parts also showed altered volatile profiles. This is the first application of HS-SPME-GC-MS on the volatiles of Rhododendron species.     

海州常山挥发性成分HS-SPME-GC-MS分析

本文首次采用顶空固相微萃取和气质联用技术(HS-SPME-GC-MS),分析了海州常山花的挥发性成分.从海州常山花中共鉴定出了27种化合物,占挥发油成分总峰面积的94.10％,主要有烷烃、醛、醇和酸类.其中含量较高的成分有2,6,10,14-四甲基十六烷(17.25％)、棕榈醛(10.57％)、1-辛烯-3-醇(6.7...     

超临界CO2提取栀子花头香精油组成研究

本文报道了用毛细血管气相色谱、色谱-质谱计算机联用技术以及薄层色谱等方法分析了采用超临界 CO_2提取的栀子花头香精油化学成分。从分离出来的58个峰中初步鉴定出24个组分,占色谱峰总面积的93％。其中主要成分是顺-3-已烯醇(1.68),惕各酸甲酯(3.92％),苯甲酸甲酯(37.34％),芳樟醇(20.54％),香苇醇(10.33％),惕各酸顺-3-已烯酯(20.30％)等。     

白木香花和果实挥发油成分的GC-MS分析

采用溶剂萃取法提取白木香(Aquilaria sinensis(Lourl.)Gilg)花和果实的挥发油,经GC-MS分析,从花挥发油中鉴定出26个化合物,占总油量的92.07%;从果实挥发油中鉴定出26个化合物,占总油量的93.66%.其中11个化合物为共有成分,且二者均含壬酸等致香成分.     

采收时间对百里香芳香油产量和化学成分的影响研究

利用水蒸汽蒸馏方法研究了生长于中国西北部不同采收时期百里香花,叶,茎和全草芳香油含量和化学成分的变化,结果表明：不同采收时期对花和叶芳香油含量却很大,而对茎中芳香油含量的影响较小,最佳采收时期在盛花期,此时不仅芳香油含量高,而且油中百里香酚和香酚的含量也高。气－质色谱图上出现了53中化合物,鉴定了其中的41中,占总成分的94．419％,芳香油中以百里香酚,香芹酚,对聚伞花素和松油烯为主,它们的含量在整个生长时期从43．953％,增加47．810％。     

Temporal relationship between emitted and endogenous floral scent volatiles in summer‐ and winter‐blooming Jasminum species

Jasminum spp. is cultivated for their fragrant flowers used in essential oil production and cosmetic uses. An attempt was made to study the temporal variations in floral scent volatiles composition including emitted, free endogenous and glycosyl‐linked volatile compounds from two summer‐blooming species namely, Jasminum auriculatum and Jasminum grandiflorum as well as from two winter‐blooming species namely, Jasminum multiflorum and Jasminum malabaricum. The overall emitted volatile organic compounds (VOCs) were found to be highest when the matrix Porapak Q 80/100 was used with dichloromethane (DCM) as elution solvent. The floral volatile emission from bud to senescence exhibited nocturnal maxima pattern for both the summer‐blooming species. Both the winter‐blooming species emitted its highest concentration at noon. The free endogenous concentrations of all VOCs were low when corresponding emitted concentrations were high. Enzymatic treatment of petal extract revealed that several aromatic volatiles including aromatic alcohols and monoterpenols are synthesized and stored in the flowers as water‐soluble glycosides; these compounds were shown to accumulate in higher amounts in flowers at late bud stage. These findings indicate the utilization of the precursors, i.e. the volatile‐conjugates, through hydrolysis followed by their release as free‐volatiles at flower opening stage. The outcome as a whole suggests a linkage among the temporal pattern of emitted volatiles, free‐endogenous volatiles and glycoside‐bound volatile compounds in all above studied Jasminum spp. and provided an overview of their floral volatilome.     

Plant Volatiles: Recent Advances and Future Perspectives

Volatile compounds act as a language that plants use for their communication and interaction with the surrounding environment. To date, a total of 1700 volatile compounds have been isolated from more than 90 plant families. These volatiles, released from leaves, flowers, and fruits into the atmosphere and from roots into the soil, defend plants against herbivores and pathogens or provide a reproductive advantage by attracting pollinators and seed dispersers. Plant volatiles constitute about 1% of plant secondary metabolites and are mainly represented by terpenoids, phenylpropanoids/benzenoids, fatty acid derivatives, and amino acid derivatives. In this review we focus on the functions of plant volatiles, their biosynthesis and regulation, and the metabolic engineering of the volatile spectrum, which results in plant defense improvement and changes of scent and aroma properties of flowers and fruits.     

Fragrance volatiles of developing and senescing carnation flowers

Thirteen major volatiles of the carnation flower fragrance signature have been identified by GC/MS. Of these, ten, hexanal, (2E)-hexenal, 1-hexanol, 2-hexanol, 3-hexen-1-ol, nonanal, benzaldehyde, benzyl alcohol, benzyl benzoate and caryophyllene, were quantified. The steady-state levels of these ten volatiles change independently as the flowers develop and senesce, suggesting that their synthesis is developmentally regulated. In addition, the chemical composition of the fragrance signature in naturally senesced flowers proved to be very different from that for flowers that had been induced to senesce prematurely by treatment with ethylene. Thus, senescence-related changes in carnation floral scent appear not to be directly regulated by ethylene. From cellular fractionation studies, it is evident that all of the volatiles, except 2-hexanol, are present in both membranous and cytosolic compartments, suggesting that their synthesis is membrane-associated and that they subsequently partition into the cytosol in accordance with partition coefficients.     

Diversity of Essential Oil-Secretory Cells and Oil Composition in Flowers and Buds of Magnolia sirindhorniae and Its Biological Activities

Magnolia sirindhorniae Noot. & Chalermglin produces fragrant flowers. The volatile oil secretary cells, quantity and quality as well as antioxidant and antimicrobial activities of the oils extracted from buds and flowers, have been investigated. The distribution of essential oil secretory cell in bud and flower revealed that the density and size of the oil cells were significantly higher in flowers compared to buds. In different floral parts, carpel has a higher oil cell density followed by gynophore and tepal. The histochemical analysis revealed the essential oil is synthesized in oil secretory cells. The volatile oil yield was 0.25 % in the buds and 0.50 % in flowers. GC/FID and GC/MS analysis identified 33 compounds contributing 83.2–83.5 % of the total essential oil composition. Linalool is the main constituent contributing 58.9 % and 51.0 % in the buds and flowers oils, respectively. The essential oil extracted from the flowers showed higher antimicrobial efficacy against Klebsiella pneumoniae and Staphylococcus aureus. Similarly, the essential oil isolated from the flowers depicts higher free radical scavenging, and antioxidant activity compared to buds’ oil.     

Flower Volatiles,Crop Varieties and Bee Responses

Pollination contributes to an estimated one third of global food production, through both the improvement of the yield and the quality of crops. Volatile compounds emitted by crop flowers mediate plant-pollinator interactions, but differences between crop varieties are still little explored. We investigated whether the visitation of crop flowers is determined by variety-specific flower volatiles using strawberry varieties (Fragaria x ananassa Duchesne) and how this affects the pollination services of the wild bee Osmia bicornis L. Flower volatile compounds of three strawberry varieties were measured via headspace collection. Gas chromatography showed that the three strawberry varieties produced the same volatile compounds but with quantitative differences of the total amount of volatiles and between distinct compounds. Electroantennographic recordings showed that inexperienced females of Osmia bicornis had higher antennal responses to all volatile compounds than to controls of air and paraffin oil, however responses differed between compounds. The variety Sonata was found to emit a total higher level of volatiles and also higher levels of most of the compounds that evoked antennal responses compared with the other varieties Honeoye and Darselect. Sonata also received more flower visits from Osmia bicornis females under field conditions, compared with Honeoye. Our results suggest that differences in the emission of flower volatile compounds among strawberry varieties mediate their attractiveness to females of Osmia bicornis. Since quality and quantity of marketable fruits depend on optimal pollination, a better understanding of the role of flower volatiles in crop production is required and should be considered more closely in crop-variety breeding.     

芹菜子的超临界CO2流体萃取物的化学成分研究

本文采用ＧＣ和ＧＣ－ＭＳ技术,就芹菜子的超临界ＣＯ２流体萃取法（ＳＦＥ－ＣＯ２）精油和水汽蒸馏法（ＳＤ）精油的化学组成作了对比研究。结果表明,ＳＤ法精油的主要成分为单萜烯烃类物质,而ＳＦＥ－ＣＯ２法精油为苯并呋喃酮类化合物。共有３２种化合物被鉴定,其中两种为首次在芹子油中被发现。     

Volatiles from rhizomes of Rhodiola rosea L

Terpenes and aroma volatiles from rhizomes of Rhodiola rosea L. from Norway have been isolated by both steam distillation and headspace solid-phase micro-extraction coupled with gas chromatography and mass spectrometry analysis. The dried rhizomes contained 0.05% essential oil with the main chemical classes: monoterpene hydrocarbons (25.40%), monoterpene alcohols (23.61%) and straight chain aliphatic alcohols (37.54%). n-Decanol (30.38%), geraniol (12.49%) and 1,4-p-menthadien-7-ol (5.10%) were the most abundant volatiles detected in the essential oil, and a total of 86 compounds were identified in both the SD and HS-SPME samples. Geraniol was identified as the most important rose-like odour compound besides geranyl formate, geranyl acetate, benzyl alcohol and phenylethyl alcohol. Floral notes such as linalool and its oxides, nonanal, decanal, nerol and cinnamyl alcohol highlight the flowery scent of rose root rhizomes.     

Profiling the chemical content of Opuntia ficus-indica flowers by HPLC–PDA-ESI-MS and GC/EIMS analyses

The qualitative and quantitative analysis of flavonoids from Opuntia ficus-indica flowers methanol extract from the Mediterranean area is described. On the basis of HPLC–PDA-ESI-MS/MS analysis seven compounds have been identified as kaempferol, quercetin, and isorhamnetin glycosylated derivatives. The total amount of flavonoids of O. ficus-indica flowers was 81.75 mg/1 g of fresh plant material, with isorhamnetin 3-O-robinobioside being the major component (52.22%). The plant flowers volatiles composition was also characterized and a total of 18 components were identified. The main constituents were found to be germacrene D (12.6%), 1-hexanol (12.3%), n-tetradecane (9.1%) and decanal (8.2%).     

Insect odour perception: recognition of odour components by flower foraging moths

Odours emitted by flowers are complex blends of volatile compounds. These odours are learnt by flower-visiting insect species, improving their recognition of rewarding flowers and thus foraging efficiency. We investigated the flexibility of floral odour learning by testing whether adult moths recognize single compounds common to flowers on which they forage. Dual choice preference tests on Helicoverpa armigera moths allowed free flying moths to forage on one of three flower species; Argyranthemum frutescens (federation daisy), Cajanus cajan (pigeonpea) or Nicotiana tabacum (tobacco). Results showed that, (i) a benzenoid (phenylacetaldehyde) and a monoterpene (linalool) were subsequently recognized after visits to flowers that emitted these volatile constituents, (ii) in a preference test, other monoterpenes in the flowers' odour did not affect the moths' ability to recognize the monoterpene linalool and (iii) relative preferences for two volatiles changed after foraging experience on a single flower species that emitted both volatiles. The importance of using free flying insects and real flowers to understand the mechanisms involved in floral odour learning in nature are discussed in the context of our findings.