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PubMed2004

Antibacterial activity of volatile component and various extracts of Spirulina platensis.

The methanol, dichloromethane, petroleum ether, ethyl acetate extracts and volatile components of Spirulina platensis were tested in vitro for their antimicrobial activity (four Gram-positive, six Gram-negative bacteria and Candida albicans ATCC 10239). GC-MS analysis of the volatile components of S. platensis resulted in the identification of 15 compounds which constituted 96.45% of the total compounds. The volatile components of S. platensis consisted of heptadecane (39.70%) and tetradecane (34.61%) as major components. The methanol extract showed more potent antimicrobial activity than dichloromethane, petroleum ether, ethyl acetate extracts and volatile components.

Anti-Bacterial Agents↗
PubMed2007

Antimicrobial activity of volatile components and various extracts of the red alga Jania rubens.

The methanol, dichloromethane, hexane, chloroform and volatile oil extracts of the red alga Jania rubens were tested in vitro for their antimicrobial activity (five Gram-positive, four Gram-negative bacteria and Candida albicans ATCC 10239). GC-MS analysis of the volatile components of J. rubens identified 40 compounds which constituted 77.53% of the total. The volatile components of J. rubens consisted of n-docosane (6.35%), n-eicosane (5.77%) and n-tetratriacontane (5.58%) as major components. The methanol and chloroform extracts (4 mg/disc) showed more potent antimicrobial activity than the hexane and dichloromethane extracts and the volatile oil of J. rubens.

Anti-Infective Agents↗
PubMed2001

Gc-olfactometry with solid phase microextraction of aroma volatiles from heated and unheated orange juice.

Solid phase micro extraction, SPME, the solventless headspace volatile extraction technique, was combined with GC-olfactometry (GCO) to examine changes in aroma active volatiles when orange juice was heated. Juice volatiles extracted from the static headspace using SPME (carboxen-polydimethylsiloxane fiber) were compared to liquid-liquid extracts. The SPME extract contained a greater proportion of terpenes. Limonene, myrcene and alpha-pinene comprised 86% of total FID peak area whereas they only comprised 24% in the pentane:ether extract. Aroma active volatiles were evaluated by three trained panelists using Osme, a GCO time-intensity procedure. Eighteen aroma active peaks were common to both heat treated and untreated juice headspace extracts. Six peaks were observed only in unheated extracts and five were found only in extracts from heated juices. Relative amounts of acetaldehyde decreased with increasing headspace exposure time and elevated desorption temperatures.

Adsorption↗
PubMed2007

Metabolomic profiling of natural volatiles: headspace trapping: GC-MS.

Plants are a fabulously rich source of naturally volatile metabolites, which are derived from a range of contrasting biochemical pathways (e.g., mono-, di-, and sesquiterpenoids, benzoates, alcohols, esters). Such volatiles may immediately be released from the plant or they may be stored, e.g., in glycosylated form for release later "on demand." Certain roles for these molecules have already been determined in that they can function as attractants (e.g., to pollinators, seed dispersers, and others) or as protectants (repellants, pathogen inhibitors, and so on). The flavor and fragrance of plant materials to humans and other animals are also, to a great extent, determined by natural volatiles. Other more sophisticated roles have also been elucidated where plant volatiles have been shown to be involved either as signal molecules to attract the predators of damaging herbivorous insects or potentially even as signal molecules warning other plants of imminent danger. As such, detailed knowledge of these components can be valuable in relation to breeding crop varieties for enhanced product quality or for achieving improved resistance to pathogens and insects. Furthermore, knowledge of the metabolites can result in a corresponding knowledge of the genes responsible for their synthesis and this can lead to dedicated strategies for their in vitro production through, e.g., reverse genetics in heterologous microbial expression systems in fermentors for the production of high-value fine chemicals. Various analytical techniques based on gas chromatography-mass spectrometry have been devised for the analysis of this complex group of metabolites. Two of these key methods are detailed in this chapter.

Arabidopsis↗
PubMed1978

Effect of volatile substances from Origanum majorana and Ocimum basilicum on spore respiration and germination of some soil fungi.

Oxygen uptake by the spores of Fusarium moniliforme, F. oxysporum, F. semitectum, F. solani, Mucor racemosus and Trichoderma viride was increased in the presence of volatile substances extracted from Origanum majorana and Ocimum basilicum. This increase was greater in the presence of volatile substances from O. basilicum than O. majorana, except in the case of F. semitectum where the reverse was true. A drop in the RQ of all the germinating spores was observed in the presence of these substances. Volatile substances from O. majorana reduced the spore germination of M. racemosus whereas the spores of T. viride were stimulated to germinate. Volatile substances from O. basilicum stimulated the spore germination of M. racemosus whereas T. viride spores were not affected.

Fusarium↗
PubMed2006

Volatiles of bacterial antagonists inhibit mycelial growth of the plant pathogen Rhizoctonia solani.

Bacterial antagonists are bacteria that negatively affect the growth of other organisms. Many antagonists inhibit the growth of fungi by various mechanisms, e.g., secretion of lytic enzymes, siderophores and antibiotics. Such inhibition of fungal growth may indirectly support plant growth. Here, we demonstrate that small organic volatile compounds (VOCs) emitted from bacterial antagonists negatively influence the mycelial growth of the soil-borne phytopathogenic fungus Rhizoctonia solani Kühn. Strong inhibitions (99-80%) under the test conditions were observed with Stenotrophomonas maltophilia R3089, Serratia plymuthica HRO-C48, Stenotrophomonas rhizophila P69, Serratia odorifera 4Rx13, Pseudomonas trivialis 3Re2-7, S. plymuthica 3Re4-18 and Bacillus subtilis B2g. Pseudomonas fluorescens L13-6-12 and Burkholderia cepacia 1S18 achieved 30% growth reduction. The VOC profiles of these antagonists, obtained through headspace collection and analysis on GC-MS, show different compositions and complexities ranging from 1 to almost 30 compounds. Most volatiles are species-specific, but overlapping volatile patterns were found for Serratia spp. and Pseudomonas spp. Many of the bacterial VOCs could not be identified for lack of match with mass-spectra of volatiles in the databases.

Anti-Bacterial Agents↗
PubMed2005

Analysis of volatile components from Ziziphora taurica subsp. taurica by steam distillation, superheated-water extraction, and direct thermal desorption with GCxGC-TOFMS.

Volatile components from the leaves of Ziziphora taurica subsp. taurica have been isolated by steam distillation, superheated-water extraction, and direct thermal desorption techniques. The volatile components were characterized by comprehensive two dimensional gas chromatography-time of flight mass spectrometry. The extraction yields from Z. taurica leaves were found to be 1.56% and 1.32% for steam distillation and superheated-water extraction respectively. The major compounds found in the volatile fractions of the leaves of Z. taurica were pulegone, terpinen-4-ol, cis-carveol, trans-carveol, and verbenone. The number of volatile components identified were 28, 30, and 41 for steam distillation, superheated-water extraction, and direct thermal desorption, respectively.

Gas Chromatography-Mass Spectrometry↗
PubMed2003

Volatile constituents of glutathione--ribose model system and its antioxidant activity.

Reaction between glutathione and ribose was carried out to study the volatiles formed via Maillard reaction and their antioxidant activity as well as their role in inhibition of LDL oxidation. The simultaneous distillation-extraction technique was used for trapping the volatile components followed by GC-MS analysis. Thirty six compounds were identified with the predominance of carbonyls and sulfur-containing compounds in the volatiles of this model system. Sensory evaluation was performed for the model system product according to the International Standard Methods (ISO). The results showed a high decrease in roasted and burnt attributes and remarkable increase in the like-boiled and roasted meat attributes. The sensory results of the model system product were confirmed by the presence of high concentrations of some volatile compounds having meat--like aroma such as 2-methyl-3-furanthiol and 2-furylmethanethiol. The radical scavenging activity of glutathione-ribose model system was quantified spectrophotometrically, using DPPH radical. The activity of the model system product was found to be slightly lower than that of gallic acid and BHA, but it was much higher than that of cinnamic acid (200 ppm. for each). A highly antioxidative activity was recorded by the model system product during the inhibition of LDL-oxidation in comparison with L-ascorbic acid as well as reduced glutathione (as a concentration of 0.5 micromol/L, for each) which may be due to the presence of some compounds such as 2-furylmethanethiol, 2-acetyl thiazole, 4-hydroxy-5-methyl-3(2H)-furanone.

Antioxidants↗
PubMed2005

Increased sulfur precursors and volatiles production by the leek Allium porrum in response to specialist insect attack.

To defend themselves against herbivory, plants use a variety of direct and indirect strategies involving induced increases in secondary substances. Species of the Allium genus (Alliaceae), such as the leek Allium porrum (L.), produce nonprotein sulfur amino acids derived from cysteine, i.e., alk(en)yl-cysteine sulfoxides that are precursors of volatile thiosulfinates and disulfides. These defend most species including the specialist leek moth, Acrolepiopsis assectella. We determined by measuring the increase in the sulfur precursor propyl-cysteine sulfoxide (PCSO) if production of this precursor is induced in response to moth attack and mechanical wounding. The concentration of PCSO was determined by HPLC in 2- or 6-mo-old leeks after attacks of various intensity either by the specialist leek moth or by a generalist moth, Agrotis ipsilon. Injury-induced release of sulfur volatiles was measured by GC/MS after the attacks. Results showed an increase in the production of sulfur compounds in both the precursor and volatile form, occurring only in association with intensive attacks by leek moths. The increase in sulfur precursors also led to an increase in the release of sulfur volatiles. This induced response may provide an effective defense strategy against the plant's main natural enemy, both directly and indirectly by attracting entomophagous insects.

Animals↗
PubMed2005

Plant-plant signaling: ethylene synergizes volatile emission in Zea mays induced by exposure to (Z)-3-hexen-1-ol.

Leaf alcohol (Z)-3-hexen-1-ol (Z-3-ol) is emitted by green plants upon mechanical damage. Exposure of intact maize plants to Z-3-ol induces the emission of a volatile blend that is typically released after caterpillar feeding and attracts natural enemies of the herbivores [herbivore-induced volatile organic compounds (HI-VOC)]. Thus, it has been suggested that Z-3-ol might have a function in indirect plant defense mediating plant-plant signaling and intraplant information transfer. Here, we demonstrate that HI-VOC induction by Z-3-ol is synergized by the phytohormone ethylene. Exposure to Z-3-ol at doses of 100 and 250 nmol induced HI-VOC emission in intact maize plants. HI-VOC emissions increased by 2.5-fold when ethylene was added. The effect of ethylene was more pronounced (5.1- to 6.6-fold) when only total sesquiterpene release was considered. In contrast, ethylene alone had no inductive effect but rather decreased the emission of the constitutive maize volatile linalool. We suggest that ethylene plays a synergistic role in plant-plant signaling mediated by green leaf volatiles.

Ethylenes↗
PubMed2006

Compatible and incompatible Xanthomonas infections differentially affect herbivore-induced volatile emission by pepper plants.

Recent studies have alerted us to the potential for conflicts between pathogen- and herbivore-induced plant defenses. The lack of studies on the induced chemical changes that simultaneous insect and pathogen attacks have on the host plant has become apparent. In the present study, we found that pepper plant volatile profiles can be differentially induced by compatible and incompatible bacterial infection and beet armyworm (BAW) damage when applied alone or in combination upon the same host. We also found that plants under simultaneous compatible bacterial and BAW attack are able to produce volatiles in quantities greater than those produced by healthy plants in response to BAW feeding. In contrast, plants exposed to the incompatible pathogen challenge showed a total volatile release below the level of healthy plants exposed to BAW damage. This suppression of BAW-induced volatiles coincided with increased methyl salicylate production from incompatible bacteria-infected plants. Feeding choice experiments revealed that, when given a choice, BAW larvae fed significantly more on leaves of plants infected with the incompatible bacteria as soon as 2 d after inoculation, while a significant increase in insect feeding on the plants infected with the compatible bacterial strain was not seen until day 4 after inoculation. Additionally, survival for third instars to pupation was significantly higher when feeding on infected plants than on healthy plants, regardless of compatibility. These results are indicative of lowered herbivore defenses due to disease progression on the plants.

Animals↗
PubMed2006

Chemical communication in Chagas disease vectors. Source, identity, and potential function of volatiles released by the metasternal and Brindley's glands of Triatoma infestans adults.

Compounds from the metasternal and Brindley's glands of the blood-sucking bug, Triatoma infestans, were identified by solid phase microextraction (SPME) and gas chromatography-mass spectrometry. Volatile compounds released by adult bugs during copulation or after mechanical disturbance were also characterized. Six compounds were identified and found consistently in all samples from metasternal glands. The most abundant were 3-pentanone, 2-methylbutanol, 3-pentanol, and an unidentified compound. The metasternal gland blends did not differ qualitatively between sexes. Compounds found in Brindley's glands were short chain acids, alcohols, esters, and a ketone with no qualitative differences between sexes. Isobutyric acid was the main component of this blend, and two new confirmed compounds were described as products of these glands: 2-butanone and 2-methylbutyric acid. 3-Pentanone was collected from the headspace over 33% of the copulating pairs of T. infestans. Volatiles found in the headspace of disturbed T. infestans adults included short-chain fatty acids, alcohols, esters, and ketones, with no qualitative differences between sexes. Both types of glands apparently discharge their contents after disturbance. However, most of the volatiles released by bugs after disturbance came from Brindley's glands. The locomotor activity of fourth instars increased significantly after stimulation with the odors emitted by disturbed adults, as compared with larvae stimulated by the odor of undisturbed adults or by clean air. We also studied the directional behavioral response of fifth instars to the disturbance scent in a locomotion compensator. Larvae exposed to volatiles released by disturbed adults walked away from the direction of the odor. The results suggest that this blend or part of it functions as an alarm pheromone for T. infestans. We suggest that the metasternal glands of this species are involved both in the sexual and the alarm contexts, and that the Brindley's glands probably have both alarm and defensive roles.

Animals↗
PubMed2006

Differences in induced volatile emissions among rice varieties result in differential attraction and parasitism of Nilaparvata lugens eggs by the parasitoid Anagrus nilaparvatae in the field.

We compared the volatiles of JA-treated plants of six rice varieties and then determined, in the laboratory and field, if they differed in attractiveness to Anagrus nilaparavate Pand et Wang, an egg parasitoid of rice planthoppers. Analyses of volatiles revealed significant differences among varieties, both in total quantity and quality of the blends emitted. On the basis of these differences, the six varieties could be roughly divided into three groups. In a Y-tube olfactometer, female wasps preferred odors from two groups. These preferences corresponded to observed parasitism rates in a field experiment. A comparison of the volatiles with results from behavioral assays and field experiments indicates that the quality (composition) of the blends is more important for attraction than the total amount emitted. The results imply that the foraging success of natural enemies of pests can be enhanced by breeding for crop varieties that release specific volatiles.

Animals↗
PubMed2007

Seasonal variation in volatile compound profiles of preen gland secretions of the dark-eyed junco (Junco hyemalis).

Quantitative stir bar sorptive extraction methodology, followed by gas chromatography-mass spectrometry (GC-MS) and element-specific atomic emission detection (AED) were utilized to analyze seasonal changes in volatile components of preen oil secretions in Junco hyemalis. Juncos were held in long days to simulate breeding conditions, or short days to simulate nonbreeding conditions. Linear alcohols (C(10)-C(18)) were the major volatile compounds found in preen oil, and in both sexes their levels were higher when birds were housed on long as opposed to short days. Methylketones were found at lower levels, but were enhanced in both sexes during long days. Levels of 2-tridecanone, 2-tetradecanone, and 2-pentadecanone were also greater on long days, but only in males. Among carboxylic acids (C(12), C(14), and C(16)), linear but not branched acids showed some differences between the breeding and nonbreeding conditions, although the individual variation for acidic compounds was large. Qualitatively, more sulfur-containing compounds were found in males than females during the breeding season. Functionally, the large increase in linear alcohols in male and female preen oil during the breeding season may be an indication of altered lipid biosynthesis, which might signal reproductive readiness. Linear alcohols might also facilitate junco odor blending with plant volatiles in the habitat to distract mammalian predators. Some of the volatile compounds from preen oil, including linear alcohols, were also found on the wing feather surface, along with additional compounds that could have been of either metabolic or environmental origin.

Animals↗
PubMed1995

Induction of volatile biosynthesis in the lima bean (Phaseolus lunatus) by leucine- and isoleucine conjugates of 1-oxo- and 1-hydroxyindan-4-carboxylic acid: evidence for amino acid conjugates of jasmonic acid as intermediates in the octadecanoid signalling pathway.

One of the most intriguing plant defense reactions against herbivores is the emission of volatiles as potentially attractive signals for the natural enemies of the attacking species. Like many other low and high molecular weight chemical defenses, volatile production is under the control of the octadecanoid signalling pathway leading to jasmonic acid (2) (threshold concentration of jasmonic acid giving rise to volatile induction in Phaseolus lunatus: approximately 100 nmol.ml-1). A significantly more active compound is the phytotoxin coronatine (3) (threshold concentration: > or = 1 nmol.ml-1). Methyl esters of 1-oxo-indanoyl-isoleucine (4) or 1-oxo-indanoyl-leucine (5), designed as readily available analogues of coronatin (3), have also been shown to be active (threshold concentration: > or = 20 nmol.ml-1). Crucially, their component parts, i.e. 1-oxo-indan-carboxylic acid and the amino acids are completely inactive. The pattern of emitted volatiles, produced by plants treated with these analogues, is largely identical to that released from coronatine- or jasmonic acid-treated plants. While the reduction of the carbonyl group of jasmonic acid (2) results in an inactive molecule, namely curcurbic acid, the methyl ester of the 1-hydroxy-indanoyl-isoleucine conjugate (8) is at least as effective as the corresponding oxo-derivatives (4) and (5) (threshold concentration: > or = 20 nmol.ml-1). The results support the concept that epi-jasmonic acid (1) may be converted into a leucine or isoleucine conjugate at an early stage in the natural signal transduction pathway. Their later interaction with a macromolecular receptor apparently requires enolization of the carbonyl group in the jasmonate moiety, yielding a planar segment which is essential for successful binding with the macromolecule. The resulting hydroxy group is implicated in the formation of a hydrogen bond in the ensuing ligand/receptor complex.

Amino Acids↗
PubMed1993

Chromatographic determination of volatile solvents and their metabolites in urine for monitoring occupational exposure.

The determination of volatile solvents and their metabolites in biological materials such as expired air, blood or urine allows the estimation of the degree of exposure of these chemicals. Chromatographic methods are now universally employed for this purpose and numerous analytical procedures are available for the determination of the most commonly used volatile solvents and their metabolites in urine. GC methods appear well adapted to the determination of the parent volatile solvents in blood and urine and may be used for the determination of their urinary metabolites, but these methods often require several prechromatographic steps. However, HPLC is becoming a powerful tool for the accurate and easy determination of urinary metabolites of volatile solvents, considering its decisive advantages for routine monitoring. Further, recent developments in HPLC could widen the usefulness of this method for most complex analytical problems that could be encountered during this measurement. However, despite the relative neglect of planar chromatography in this area of concern and considering the great interest in methods that could permit the simultaneous assay of numerous samples often required by routine monitoring, new approach using improved methods such as overpressured TLC could be very fruitful in the future.

Air Pollutants↗
PubMed2004

An alternative method for predicting organic solute volatilization rates under gas and liquid turbulence.

A method for predicting organic compound volatilization rates under turbulent liquid and gas conditions is developed. The reference compounds are classified according to their physico-chemical properties. The mass transfer coefficient (K(OL)) ratios for organic solutes to the reference compounds are constant for a wide range of environmental conditions, including liquid or air turbulence, or both at once. The obtained results indicate that when the environmental conditions are the same the determination of the volatilization rates is strongly dependent on the solute properties and the chemical structure. The presented method can more effectively estimate the volatilization rates of the solutes than the traditional one under various environmental conditions especially for low volatility solutes. The advantages and disadvantages of the traditional method are also discussed.

Air Movements↗
PubMed2004

Comparison of different extraction methods for the analysis of volatile secondary metabolites of Lippia alba (Mill.) N.E. Brown, grown in Colombia, and evaluation of its in vitro antioxidant activity.

Hydrodistillation (HD), simultaneous distillation solvent extraction (SDE), microwave-assisted hydrodistillation (MWHD), and supercritical fluid (CO2) extraction (SFE) were employed to isolate volatile secondary metabolites from fresh leaves and stems of Colombian Lippia alba (Mill.) N.E. Brown. Kovàts indices, mass spectra or standard compounds were used to identify around 40 components in the various volatile fractions. Carvone (40-57%) was the most abundant component, followed by limonene (24-37%), bicyclosesquiphellandrene (5-22%), piperitenone (1-2%), piperitone (ca. 1.0%), and beta-bourbonene (0.6-1.5%), in the HD, SDE, MWHD, and SFE volatile fractions. Static headspace (S-HS), simultaneous purge and trap in solvent (CH2Cl2) (P&T), and headspace solid-phase microextraction (HS-SPME) were used to sample volatiles from fresh L. alba stems and leaves. The main components isolated from the headspace of the fresh plant material were limonene (27-77%), carvone (14-30%), piperitone (0.3-0.5%), piperitenone (ca. 0.4%), and beta-bourbonene (0.5-6.5%). The in vitro antioxidant activity of L. alba essential oil, obtained by hydrodistillation was evaluated by determination of hexanal, the main carbonyl compound released by linoleic acid subjected to peroxidation (1 mm Fe2+, 37 degrees C, 12 h), and by quantification of this acid as its methyl ester. Under the same conditions, L. alba HD-essential oil and Vitamin E exhibited similar antioxidant effects.

Antioxidants↗