Distribution of enantiomers of volatile organic compounds in selected fruit distillates

The enantiomer ratios of chiral volatile organic compounds in fruit distillates were determined by multidimensional gas chromatography using solid‐phase microextraction (SPME) as a sample treatment procedure. Linalool and its oxides, limonene, α‐terpineol, and nerolidol, were present at the highest concentration levels, while significantly lower amounts of β‐citronellol and lactones were found in the studied samples. However, almost all terpenoids mainly occur as a racemic or near‐racemic mixture; enantiomer distribution of some chiral organic compounds in fruit distillates correlated to a botanical origin. In particular, a significant enantiomeric excess of (R)‐linalool and (S)‐α‐terpineol was found only for pear brandy, and likewise the dominance (R)‐limonene and the second eluted enantiomer of nerolidol for Sorbus domestica and strawberry, respectively. The distribution of γ‐lactones stereoisomers was more nonspecific, with a general excess of the R‐enantiomer.     

Susceptibility and intrinsic tolerance of Pseudomonas aeruginosa to selected plant volatile compounds

AIMS: To examine the causes for variations in sensitivity and intrinsic tolerance of Pseudomonas aeruginosa to plant volatile compounds. METHODS AND RESULTS: Minimum inhibitory concentrations were determined for a selection of volatile phytochemicals against P. aeruginosa using a microdilution assay. Effects on growth were also assessed in 100-ml broth cultures. The two strains of P. aeruginosa included in the study exhibited intrinsic tolerance to all compounds, with the exception of carvacrol and trans-cinnamaldehyde. The protonophore carbonyl cyanide m-chlorophenylhydrazone increased P. aeruginosa sensitivity to all compounds except trans-cinnamaldehyde, implicating an ATP-dependent efflux mechanism in the observed tolerance. Outer membrane integrity following treatment with test compounds was assessed by measuring sensitization to detergents. Only carvacrol caused damage to the outer membrane of P. aeruginosa. CONCLUSIONS: The intrinsic tolerance of P. aeruginosa strains to plant volatile compounds is associated with an active efflux mechanism and the barrier function of the outer membrane. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings offer an explanation for the intrinsic tolerance to plant volatile compounds exhibited by P. aeruginosa. The study also confirms that the outer membrane-permeabilizing action of carvacrol, previously reported for the gram-negative bacteria Escherichia coli and Salmonella, extends to monoterpene-tolerant strains of P. aeruginosa.     

An optimized protocol for large‐scale in situ sampling and analysis of volatile organic compounds

Chemical ecology is an ever‐expanding field with a growing interest in population‐ and community‐level studies. Many such studies are hindered due to lack of an efficient and accelerated protocol for large‐scale sampling and analysis of chemical compounds. Here, we present an optimized protocol for such large‐scale study of volatiles. A large‐scale in situ study to understand role of semiochemicals in variation in mating success of lekking blackbuck was conducted. Suitable methods for sampling and statistical analysis were identified by testing and comparing the efficiencies of available techniques to reduce analysis time while retaining sensitivity and comprehensiveness. Solid‐phase extraction using polydimethylsiloxane, analysis using a semiautomated detection of retention time and base peak, and statistical analysis using random forest algorithm were identified as the most efficient methods for large‐scale in situ sampling and analysis of volatiles. The protocol for large‐scale volatile analysis can facilitate evolutionary and metaecological studies of volatiles in situ from all types of biological samples. The protocol has potential for wider application with the analysis and interpretation methods being suitable for all kinds of semiochemicals, including nonvolatile chemicals.     

Detection and analysis of endogenous polar volatile organic compounds (PVOCs) in urine for human exposome research

Background: The human exposome, defined as ‘…everything that is not the genome’, comprises all chemicals in the body interacting with life processes. The exposome drives genes x environment (GxE) interactions that can cause long-term latency and chronic diseases. The exposome constantly changes in response to external exposures and internal metabolism. Different types of compounds are found in different biological media.

Objective: Measure polar volatile organic compounds (PVOCs) excreted in urine to document endogenous metabolites and exogenous compounds from environmental exposures.

Methods: Use headspace collection and sorbent tube thermal desorption coupled with bench-top gas chromatography-mass spectrometry (GC-MS) for targeted and non-targeted approaches. Identify and categorize PVOCs that may distinguish among healthy and affected individuals.

Results: Method is successfully demonstrated to tabulate a series of 28 PVOCs detected in human urine across 120 samples from 28 human subjects. Median concentrations range from below detect to 165?ng/mL. Certain PVOCs have potential health implications.

Conclusions: Headspace collection with sorbent tubes is an effective method for documenting PVOCs in urine that are otherwise difficult to measure. This methodology can provide probative information regarding biochemical processes and adverse outcome pathways (AOPs) for toxicity testing.     

Variation in volatile organic compounds in fruits of Iranian Capparis spinosa L. accessions

In the present study, essential oil (EO) content and phytochemical variation were evaluated in the fruits of 10 Iranian Capparis spinosa accessions. The accessions were collected from their natural habitats of Iran and grown together in field conditions. The EOs content ranged from 0.55 to 1.46%. The correlation analysis revealed a significant negative correlation between the EO content and altitude of the sampling locations (P < 0.01; r = −0.84). GC–MS analysis revealed 31 compounds in the EOs of the accessions, mainly being isopropyl isothiocyanate (5.5–13.7%), methyl sulfonyl heptyl isothiocyanate (4.6–15.6%), butyl isothiocyanate (3.6–10.6%), γ-terpinene (4.4–9.2%), and thymol (22.9–37.1%). According to the cluster analysis, the accessions were classified into three groups. Principal component analysis (PCA) demonstrated that the first and second PCs1 confirmed more than 76% of the total variation in the phytochemical components among the C. spinosa samples. Our results revealed that the sampling altitude was the most effective factor in explaining this variation.     

Recent advances in two-phase partitioning bioreactors for the treatment of volatile organic compounds

Biological processes are considered to be the most cost-effective technology for the off-gas treatment of volatile organic compounds (VOC) at low concentrations. Two-phase partitioning bioreactors (TPPBs) emerged in the early 1990s as innovative multiphase systems capable of overcoming some of the key limitations of traditional biological technologies such as the low mass transfer rates of hydrophobic VOCs and microbial inhibition at high VOC loading rates. Intensive research carried out in the last 5 years has helped to provide a better understanding of the mass transfer phenomena and VOC uptake mechanisms in TPPBs, which has significantly improved the VOC biodegradation processes utilizing this technology platform. This work presents an updated state-of-the-art review on the advances of TPPB technology for air pollution control. The most recent insights regarding non-aqueous phase (NAP) selection, microbiology, reactor design, mathematical modeling and case studies are critically reviewed and discussed. Finally, the key research issues required to move towards the development of efficient and stable full-scale VOC biodegradation processes in TPPBs are identified.     

鸡屎藤挥发油化学成分的研究

利用气相色谱－质谱联用（ＧＣ／ＭＳ）技术对鸡屎藤挥发油化学成分进行分析研究,初步鉴定了３１种成分,它们占挥发油总量的７７．１６％,其中含量友上的有乙氧戊烷、乙酸异戊酯、苯甲醛、己酸乙酯、甲酸苯甲酯、乙酸苯甲酯、乙酸－２－苯乙酯、５,６,７,７ａ－四氢－４,４,７ａ－三甲基－２（４Ｈ）－苯并呋喃酮、十五碳酸乙酯、十六碳酸和癸酸异戊酯等１１种成分。     

小蓬草精油的分离组分比较分析

通过薄层色谱分析和柱色谱分离结合气相色谱-质谱分析小蓬草精油的分离组分,结果表明其不同分离组分组成有差异,可以分离得到以香芹酮(18.33%)为特征成分,含有cis-香芹醇(3.79%),cis-香芹酮氧化物(1.74%),trans-香芹醇(1.62%),橙花叔醇(1.13%),石竹烯氧化物(0.38%),对甲基苯乙酮(0.64%)或者是以cis-香芹醇为特征成分,含有cis-马鞭草烯酮的分离组分。香芹酮、cis-香芹醇、橙花叔醇、对甲基苯乙酮、cis-马鞭草烯酮等是具有香气的化合物。     

Application of multidimensional gas chromatography to the enantioselective characterisation of the essential oil of Eupatorium buniifolium Hooker et Arnott

The qualitative and quantitative composition of the essential oil from aerial parts of Eupatorium buniifolium Hooker et Arnott (Asteraceae) has been investigated for the first time. The essential oils were obtained by steam distillation of leaves and analysed by GC-MS; 44 components were identified. Monoterpene and sesquiterpene hydrocarbons, especially alpha-pinene (14.7%), beta-elemene (12.2%), germacrene D (11.5%), trans-beta-guaiene (6.5%) and (E)-caryophyllene (4.3%), were the major constituents found in the oils. The characterisation of E. buniifolium by enantioselective GC was performed by evaluation of the enantiomeric ratios of alpha-pinene, sabinene, beta-pinene, limonene, terpinen-4-ol and germacrene D.     

Response of Biomass Development,Essential Oil,and Composition of Plectranthus amboinicus (Lour.) Spreng. to Irrigation Frequency and Harvest Time

A greenhouse experiment was conducted to study the effects of four irrigation intervals (4, 8, 12, and 16 days) and six harvests (2, 4, 6, 8, 10, and 12 months after transplanting) on biomass, essential oil content, and composition of Plectranthus amboinicus (Lour .) Spreng . Fresh weight and essential oil yield decreased with increasing irrigation interval; whereas, essential oil content was stimulated by water stress and increased as the irrigation interval increased. Fresh weight of Plectranthus amboinicus irrigated every 4 days peaked when harvested at 6 months, but essential oil content peaked when irrigated every 16 days and harvested at 2 months after transplantation. On the other hand, essential oil yield peaked when irrigated every 8 days and harvested at 6 months. Thymol, p‐cymene, γ‐terpinene, and β‐caryophyllene were the major compounds, and they peaked at different irrigation intervals and harvest times. This study showed biomass, essential oil content, and yield as well as the major and minor constituents of Plectranthus amboinicus are influenced by irrigation interval and the timing of harvest.     

Optical sensory arrays for the detection of urinary bladder cancer‐related volatile organic compounds

Non‐invasive detection of urinary bladder cancer remains a significant challenge. Urinary volatile organic compounds (VOCs) are a promising alternative to cell‐based biomarkers. Herein, we demonstrate a novel diagnosis system based on an optic fluorescence sensor array for detecting urinary bladder cancer VOCs biomarkers. This study describes a fluorescence‐based VOCs sensor array detecting system in detail. The choice of VOCs for the initial part was based on an extensive systematic search of the literature and then followed up using urinary samples from patients with urinary bladder transitional cell carcinoma. Canonical discriminant analysis and partial least squares discriminant analysis (PLS‐DA) were employed and correctly detected 31/48 urinary bladder cancer VOC biomarkers and achieved an overall 77.75% sensitivity and 93.25% specificity by PLS‐DA modelling. All five urine samples from bladder cancer patients, and five healthy controls were successfully identified with the same sensor arrays. Overall, the experiments in this study describe a real‐time platform for non‐invasive bladder cancer diagnosis using fluorescence‐based gas‐sensor arrays. Pure VOCs and urine samples from the patients proved such a system to be promising; however, further research is required using a larger population sample.      

Broad-spectrum antimicrobial activity of volatile organic compounds from endophytic Pseudomonas putida BP25 against diverse plant pathogens

ABSTRACT

Black pepper endophytic Pseudomonas putida BP25 produced diverse antimicrobial volatile organic compounds having potential for plant disease management. Chemically synthesised volatiles such as 2, 5-dimethyl pyrazine; 2-methyl pyrazine; dimethyl trisulphide; 2-ethyl 5-methyl pyrazine; and 2-ethyl 3, 6-dimethyl pyrazine showed inhibitory activity against oomycete pathogens, Phytophthora capsici & Pythium myriotylum; fungal pathogens, Rhizoctonia solani, Colletotrichum gloeosporioides, Athelia rolfsii, Gibberella moniliformis & Magnaporthe oryzae; bacterial pathogen, Ralstonia pseudosolanacearum and plant parasitic nematode, Radopholus similis. Among them, dimethyl trisulphide completely inhibited oomycete and fungal pathogens as well as R. similis at a concentration of 2.65?µg?cm^?3 under in vitro conditions. Pyrazines suppressed Phytophthora lesions on shoot cuttings of black pepper upon in planta volatile treatment. Dimethyl trisulphide was the only compound that exhibited soil fumigant activity against P. capsici, R. solani and A. rolfsii (6.25?µg?cm^?3), C. gloeosporioides and G. moniliformis (12.5?µg?cm^?3), and R. similis (50?µg?cm^?3). Altogether, endophytic Pseudomonas putida BP25 and its volatile organic compounds offer an alternative strategy for eco-friendly disease management in agriculture.     

丁香油酚和乙酸香茅酯对蜂王信息素活性的影响:量子化学研究

植物次生代谢物质可影响昆虫信息素的功能,但有关影响机制尚不清楚。本文利用量子化学理论分析了广泛存在于花粉或花蜜中的挥发性丁香油酚和乙酸香茅酯能否与蜜蜂蜂王信息素挥发性成分4-羟基-3-甲氧苯乙醇(HVA)反应。使用Gaussian 09软件来完成几何优化、过渡态搜索、频率分析,并计算了反应能垒和速率常数。结果表明,丁香油酚和HVA分别与OH自由基反应生成有机自由基后,通过自由基-自由基途径发生聚合反应(反应能垒为0.613077 kcal/mol,反应速率常数为9.559953×1011cm3/molecule/s),而不易通过自由基-分子途径发生反应(反应能垒为31.792769 kcal/mol,反应速率常数为4.268854×10-13cm3/molecule/s)。相似地,乙酸香茅酯和HVA分别与OH自由基反应后,也可通过自由基-自由基途径发生反应(反应能垒为2.086469 kcal/mol,反应速率常数为2.328216×1011cm3/molecule/s),但不易通过自由基-分子途径发生反应(反应能垒为25.881002 kcal/mol,反应速率常数为1.513828×10-8cm3/molecule/s)。由于全球环境变化可能导致大气中OH自由基浓度升高,使得花蜜或花粉中挥发性不饱和化合物有可能影响蜂王信息素的功能,从而干扰蜂群的化学通讯。     

Odours and volatile organic compounds emitted from municipal solid waste at different stage of decomposition and relationship with biological stability

Odours (OU_E) and volatile organic compounds (VOC) emission during biological process used to treat MSW were studied under standardized conditions in order to detect potential risk for workers and population. Results obtained indicated that odours and VOCs emitted depend on the biological stability of waste measured by the dynamic respiration index (DRI) and a very good correlation were found between these parameters (OU_E vs. DRI, r = 0.96, p < 0.001, n = 6; VOC vs. DRI, r = 0.97, p < 0.001, n = 6).GC-MS study of the VOCs indicated the presence of a group of molecules that were degraded during the process. On the other hand, a second group of molecules, i.e. aromatic and halogenated compounds, and furan persisted in the waste sample, although molecule concentrations were always lower than Threshold Limit Value-Time Weighted Average (TLV-TWA).     

不同青花椒品种挥发油成分的对比分析

青花椒产业近年来在南方地区发展迅速,而与品质相关的基础研究却较为滞后。本研究以市场上主要的八个青花椒品种为研究对象,采用水蒸气蒸馏法提取青花椒中的挥发油,结合气相色谱-质谱联用技术(gas chromatography-mass spectrometry,GC-MS)分析挥发油成分并进行聚类分析。结果显示,八个青花椒品种挥发油含量差异较大,在八种青花椒中共鉴别出60种成分,占挥发油相对含量的99.76%～99.66%,其中有29种共有成分,占挥发油含量的96.64%～98.95%。这些共有成分主要为醇类和烯类,含量较高的为芳樟醇和柠檬烯。八个青花椒品种挥发油的主要挥发性成分相似但含量相差较大,多数非共有挥发性成分含量少于1%,根据共有挥发性成分含量的差异,将八个青花椒品种分为了两类。对不同青花椒品种挥发油成分及含量的分析,可为青花椒的品质评价、品种选育及开发利用提供参考。     

Gas phase photocatalytic degradation on TIO2 pellets of volatile chlorinated organic compounds from a soil vapor extraction well

The degradation of trichloroethylene (TCE, Cl₂C=CHCl) and tetrachloroethylene (PCE, Cl₂C=CCI₂) in a gas stream from a soil vapor extraction (SVE) well was demonstrated with an annular photocatalytic reactor packed with porous TiO₂ pellets in a field trial at the Savannah River Site in Aiken, SC. The TiO₂ pellets were prepared using a sol‐gel method. The experiments were performed at 55 to 60°C using space times of 10⁸ to 10¹⁰ g ? s ? mol^‐1 for TCE and PCE. Chloroform (CHCl₃) and carbon tetrachloride (CCl₄) were detected as minor products from side reactions. On a molar basis, the amounts CCl₄ and CHCl₃ produced were about 2 and 0.2% of the reactants, respectively.     

A facile means for the identification of indolic compounds from plant tissues

The bulk of indole‐3‐acetic acid (IAA) in plants is found in the form of conjugated molecules, yet past research on identifying these compounds has largely relied on methods that were both laborious and inefficient. Using recent advances in analytical instrumentation, we have developed a simple yet powerful liquid chromatography–mass spectrometry (LC–MS)‐based method for the facile characterization of the small IAA conjugate profile of plants. The method uses the well‐known quinolinium ion (m/z 130.0651) generated in MS processes as a signature with high mass accuracy that can be used to screen plant extracts for indolic compounds, including IAA conjugates. We reinvestigated Glycine max (soybean) for its indoles and found indole‐3‐acetyl‐trytophan (IA‐Trp) in addition to the already known indole‐3‐acetyl‐aspartic acid (IA‐Asp) and indole‐3‐acetyl‐glutamic acid (IA‐Glu) conjugates. Surprisingly, several organic acid conjugates of tryptophan were also discovered, many of which have not been reported in planta before. These compounds may have important physiological roles in tryptophan metabolism, which in turn can affect human nutrition. We also demonstrated the general applicability of this method by identifying indolic compounds in different plant tissues of diverse phylogenetic origins. It involves minimal sample preparation but can work in conjunction with sample enrichment techniques. This method enables quick screening of IAA conjugates in both previously characterized as well as uncharacterized species, and facilitates the identification of indolic compounds in general.     

鄂西香茶菜中挥发油成分分析

采用水蒸汽蒸馏法分别从鄂西香茶菜的叶、花和果实中提取挥发油,并用气相色谱-质谱联用技术（GC-MS）对其挥发油中的化学成分进行分离和结构鉴定,运用气相色谱峰面积归一化法确定各成分的相对百分含量。从鄂西香茶菜的3种挥发油中共鉴定出39种成分,分别从叶、花及果实中鉴定出18、19和23种成分,其中只有6种成分在这3个部位都被鉴出,3种不同部位得到的挥发油成分差异较大。它们的挥发油中主要成分为单萜、倍半萜和二萜类化合物。