Development, optimization and validation of automated volatile organic compound data analysis using an on-line thermal desorption gas chromatograph with dual detection and application to measurements in ambient air.

Because of their major role in indoor and outdoor air pollution, even at trace levels, VOCs are of great interest, and their monitoring requires sensitive analytical instruments. Several techniques are commonly used, such as portable sensors, Proton Transfer Reaction Mass Spectrometry (PTR-MS) and Thermal Desorption Gas Chromatography (TD-GC). The latter is widely used off- and on-line with Flame Ionization Detectors (FID) or Mass Spectrometers (MS). Given the large number of molecules detected per chromatogram, the data generated by these monitoring techniques are usually checked and reprocessed manually. This process is extremely time consuming and could result in human error. The challenge is to provide reliable results as quickly as possible. In this study, the performances of an on-line TD-GC system with dual detection FID and MS were tested. The Method Detection Limits (MDL), linearities and accuracies of 60 VOCs (alkanes, aromatics, oxygenated and halogenated) were calculated both for FID and MS detectors. The MDLs and accuracies ranged from 0.006 to 0.618 ppbv and from 77 % to 100 % for FID, and from 0.018 to 0.760 ppbv and from 80 % to 100 % for MS. Both detectors showed good complementarity and allowed the development of two programs to facilitate data analysis. These algorithms were designed to autonomously select optimal results between FID and MS detectors, and were evaluated for outdoor and indoor measurement conditions. Measuring VOCs in field campaigns is challenging, and it is anticipated that these programs could be extended to other types of dual-detector systems or for the comparison of data from different calibrated instruments.

Volatile compositions and glandular trichomes of Zataria multiflora in different phenological stages under normal and drought stress conditions.

BACKGROUND: Zataria multiflora Boiss. is a medicinal and aromatic plant from the Lamiaceae family. It is extensively used in Iranian traditional medicine, mostly as a replacement for Thyme species. This study was focused on the analysis of chemical composition and the distribution and types of trichomes of Z. multiflora grown under different conditions. Equilibrium headspace analysis in combination with GC-FID-MS was used to identify volatile compounds released by aerial parts of Z. multiflora in development stages of 50 and 100% flowering under normal and drought-stress conditions. RESULTS: The main constituents were p-cymene (20.06-27.40%), γ-terpinene (12.44-16.93%), and α-pinene (6.91-16.58%) and thymol (8.52-9.99%). The highest content of p-cymene (27.40%) and thymol (9.99%) was observed in the 50% flowering stage at the 90% field capacity, while the maximum γ-terpinene (16.93%) content was recorded in the 100% flowering stage under normal conditions. Using the SEM method, it was found that peltate glandular and non-glandular trichomes are distributed on the surface of the leaf, stem, and outer side of the calyx. However, capitate trichomes only are detected on the stem and calyx in the 100% flowering and beginning of blooming stages, respectively. The type and structure of trichomes do not vary in different development stages, but they differ in density. The highest number of leaf peltate glandular trichomes was observed in the vegetative and beginning of blooming stages at 50% and 90% field capacity, respectively. Non-glandular trichomes of the stem were observed with high density in both normal and stress conditions, which are more densely in 90% field capacity. CONCLUSIONS: Since this plant has strong potential to be used in the food and pharmacological industries, this study provides valuable information for its cultivation and harvesting at specific phenological stages, depending on desired compounds and their concentrations.

Chemical Analysis and Investigation of Antimicrobial and Antibiofilm Activities of Prangos trifida (Apiaceae).

Plants of the genus Prangos are intensively investigated as potential new sources of bioactive isolated products. In this work, the chemical composition of volatile constituents (essential oils and headspace volatiles) and dichloromethane extracts, as well as antimicrobial and antibiofilm activities of essential oils and MFDEs (methanol fractions of dichloromethane extracts) of Prangos trifida from Serbia, were investigated. Volatiles of roots, leaves, stems and fruits, and fatty acids and phytosterols in dichloromethane extracts of roots and fruits were analyzed by GC-FID-MS, whereas coumarins in MFDEs by LC-MS and some isolated coumarins by 1H-NMR. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations/minimum fungicidal concentrations (MBCs/MFCs) of essential oils and MFDEs were determined against 13 microorganisms. Antibiofilm activity was assessed against four microorganisms. Additionally, congo red and ergosterol binding assays were conducted to elucidate selected mechanisms of antibiofilm action in the case of Candida albicans. Total of 52 volatile constituents, 16 fatty acids, eight phytosterols and 10 coumarins were identified. Essential oils demonstrated significant activity, surpassing that of commercial food preservatives, against six tested molds from the Aspergillus, Penicillium and Trichoderma genera, as well as against bacteria Staphylococcus aureus and Bacillus cereus. Most of the oils strongly inhibited the formation of biofilms by S. aureus, Listeria monocytogenes and Escherichia coli. MFDEs exhibited noteworthy effects against B. cereus and the tested Aspergillus species, particularly A. niger, and significantly inhibited C. albicans biofilm formation. This inhibition was linked to a marked reduction in exopolysaccharide production, while antifungal mechanisms associated with ergosterol remained unaffected.

Effect-Directed, Chemical and Taxonomic Profiling of Peppermint Proprietary Varieties and Corresponding Leaf Extracts.

During the development of novel, standardized peppermint extracts targeting functional applications, it is critical to adequately characterize raw material plant sources to assure quality and consistency of the end-product. This study aimed to characterize existing and proprietary, newly bred varieties of peppermint and their corresponding aqueous extract products. Taxonomy was confirmed through genetic authenticity assessment. Non-target effect-directed profiling was developed using high-performance thin-layer chromatography-multi-imaging-effect-directed assays (HPTLC-UV/Vis/FLD-EDA). Results demonstrated substantial differences in compounds associated with functional attributes, notably antioxidant potential, between the peppermint samples. Further chemical analysis by high-performance liquid chromatography-photodiode array/mass spectrometry detection (HPLC-PDA/MS) and headspace solid-phase microextraction-gas chromatography-flame ionization/MS detection (headspace SPME-GC-FID/MS) confirmed compositional differences. A broad variability in the contents of flavonoids and volatiles was observed. The peppermint samples were further screened for their antioxidant potential using the Caenorhabditis elegans model, and the results indicated concordance with observed content differences of the identified functional compounds. These results documented variability among raw materials of peppermint leaves, which can yield highly variable extract products that may result in differing effects on functional targets in vivo. Hence, product standardization via effect-directed profiles is proposed as an appropriate tool.

A study on the impact of harvesting operations on the mineral oil contamination of olive oils.

During the 2020-21 olive oil campaign, the contribution of harvesting operations to mineral oil saturated (MOSH) and aromatic hydrocarbon (MOAH) contamination was studied. Oils extracted from hand-picked olives (15 different olive groves) generally had background MOSH (<2.7 mg/kg), and no quantifiable MOAH. In 40% of the cases, an important contamination increase was observed after harvesting operations. Except for one sample (325.8 and 111.0 mg/kg of MOSH and MOAH, respectively), other samples reached 4.3-33.7 mg/kg of MOSH and 1.1-11.3 mg/kg of MOAH. Accidental leaks of lubricants and/or contact with lubricated mechanical parts, were identified as important sources of contamination. Chromatographic traces obtained by on-line high-performance liquid chromatography (HPLC)-gas chromatography (GC)-flame ionization detection (FID) allowed for source identification. A comprehensive two-dimensional gas chromatographic platform (GC × GC) with parallel FID/MS detection was implemented for confirmation and to attempt the characterization of the contaminations. Good harvesting practices are suggested to minimize contamination risks.

Elucidation of the Lipid Composition of Hemp (Cannabis sativa L.) Products by Means of Gas Chromatography and Ultra-High Performance Liquid Chromatography Coupled to Mass Spectrometry Detection.

The growing demand in natural matrices that represent a source of dietary and nutraceutical molecules has led to an increasing interest in Cannabis sativa, considered to be a multipurpose, sustainable crop. Particularly, the considerable content in essential fatty acids (FAs) makes its derived-products useful food ingredients in the formulation of dietary supplements. In this research, the FA and triacylglycerol (TAG) composition of hempseed oils and flours were investigated using gas chromatography coupled to mass spectrometry and flame ionization detection as well as liquid chromatography coupled to mass spectrometry (LC-MS), respectively. Furthermore, a recently introduced linear retention index (LRI) approach in LC was successfully employed as a useful tool for the reliable identification of TAG species. A total of 30 FAs and 62 glycerolipids were positively identified in the investigated samples. Relative quantitative analyses confirmed linoleic acid as the most abundant component (50-55%). A favorable omega6/omega3 ratio was also measured in hemp-derived products, with the α-linolenic acid around 12-14%. Whereas, γ-linolenic acid was found to be higher than 1.70%. These results confirm the great value of Cannabis sativa as a source of valuable lipids, and the further improvement of the LRI system paves the way for the automatization of the identification process in LC.

Antimicrobial and lipase inhibition of essential oil and solvent extracts of Cota tinctoria var. tinctoria and characterization of the essential oil.

The essential oil (EO) of Cota tinctoria var. tinctoria was analyzed using GC-FID / MS. A total of 51 compounds were determined from this taxon, accounting for 99.79% in hydrodistillation. Monoterpenes were the primary chemical class for the volatile organic compounds in the EO (36.1%, 13 compounds). Borneol (18.1%), camphor (14.9%), and ß-pinene (11.3%) were the major components in the EO of C. tinctoria var. tinctoria. The antimicrobial activities of EO and n-hexane, acetonitrile, methanol, and water solvent extracts of the taxon were screened in vitro against ten microorganisms. The EO yielded the best activity (15 mm, 372.5 MIC, 59600 µg/µL) against Mycobacterium smegmatis. The acetonitrile extract was the most active against the Staphylococcus aureus and Bacillus cereus with 274 µg/mL MIC value. IC50 values for the lipase enzyme inhibitory activity of EO and solvent extracts (n-hexane, acetonitrile, methanol, and water) were found to be 59.80 ± 4.3285 µg/mL 68.28 ± 3.1215 µg/mL, 52.60 ± 3.7526 µg/mL, 48.73 ± 2.8265 µg/mL, and 99.50 ± 5.5678 µg/mL, respectively.

Chemical Variation, Antimicrobial, Nitric Oxide Scavenging Activities and Tyrosinase Inhibition of Essential Oils and Solvent Extracts from Filipendula vulgaris Moench Growing in Turkey.

Volatile organic compositions of the essential oils (EOs), solid-phase microextraction (SPME) and SPME of n-hexane extracts from the flower and stem-leaf of Filipendula vulgaris (F. vulgaris) were analyzed by GC-FID/MS. A total of 107 constituents were characterized, flower and stem-leaf parts of the plant were found to contain different volatile organic compounds. Tricosane (29.6%), n-nonanal (20.5%) were identified as the main components in the essential oil of the flower, while phytol (35.2%) was found to be a major constituent in the essential oil of stem-leaf. Benzaldehyde (56.0%) and n-nonanal (31.6%) were the major groups in the SPME of stem-leaf and flower, respectively. The volatiles for the SPME of n-hexane extracts of the flower and stem-leaf of F. vulgaris were predominated by aromatic compounds (75.0% and 78.5%) and ketones (18.1% and 10.1%), respectively. On the other hand, a total of terpene compounds was found at the most in the EO of the stem-leaf part of the plant (48.6%). In addition, antimicrobial, tyrosinase inhibition, and nitric oxide scavenging activities of the n-hexane (H), methanol (M), aqueous extracts (A) and EOs of F. vulgaris were investigated. EOs and methanol extracts of flower and stem-leaf had high antimicrobial activity against tested various microorganisms. However, n-hexane extracts of the flower and stem-leaf only displayed activity against Mycobacterium smegmatis. Methanol extracts of flower and stem-leaf possessed the best tyrosine inhibition and NO scavenging activity.

Stationary monitoring and source apportionment of VOCs in a chemical industrial park by combining rapid direct-inlet MSs with a GC-FID/MS.

Fast and comprehensive monitoring of VOCs, required for air quality management in large-scale chemical industrial parks in China, cannot be accomplished by stationary measurements using conventional GC-FID or GC-MS alone due to their low temporal resolutions and limited detectable ranges. Novel direct-inlet mass spectrometry (DI-MS) has been widely applied for real-time monitoring of VOCs. To verify its applicability in industrial settings, high mass-resolution proton-transfer-reaction time-of-flight MS (HMR-PTR-TOFMS), single-photon ionization time-of-flight MS (SPI-TOFMS), together with online GC-FID/MS were simultaneously deployed at the boundary of one of the largest chemical industrial parks in eastern China. Aromatics, acetonitrile, acetic acid, ethyl acetate, aliphatic hydrocarbons, 1,2-dichloroethane, and acetone were detected as the main pollutants. These three instruments detected 12 common species, among which ethyl acetate, toluene, C8-aromatics, and methyl ethyl ketone showed similar time series and levels. Acetone, benzene, chlorobenzene, styrene, and C9-aromatics showed only similar time series. The HMR-PTR-TOFMS uniquely detected 14 species, mainly oxidized VOCs, nitriles, and amines, which greatly helps acknowledge the pollutants in the chemical industrial area. Positive matrix factorization, using the HMR-PTR-TOFMS and GC-FID/MS datasets, was used to identify eight sources. Four of the identified sources were mainly detected by the HMR-PTR-TOFMS, with pollutants mainly comprised of nitriles, amines, carbonyls, and organic acids, most of which were hazardous and/or odorous. These four sources accounted for 41.5% and 33.2% of the total VOCs and ozone formation potential, respectively. The complementary nature of GC-FID/MS and HMR-PTR-TOFMS in VOC source apportionment in industrial settings is of great practical use for advanced VOCs abatement. Thus, the high mass resolution DI-MSs are suggested to be a supplementary measurement for fence-line monitoring. Although with a relatively short period attempt, this study has wide implications for the fence-line stationary observational modes and source apportion methods combining with traditional observations.

GC-FID-MS Based Metabolomics to Access Plum Brandy Quality.

Plum brandy (Slivovitz (en); Sljivovica(sr)) is an alcoholic beverage that is increasingly consumed all over the world. Its quality assessment has become of great importance. In our study, the main volatiles and aroma compounds of 108 non-aged plum brandies originating from three plum cultivars, and fermented using different conditions, were investigated. The chemical profiles obtained after two-step GC-FID-MS analysis were subjected to multivariate data analysis to reveal the peculiarity in different cultivars and fermentation process. Correlation of plum brandy chemical composition with its sensory characteristics obtained by expert commission was also performed. The utilization of PCA and OPLS-DA multivariate analysis methods on GC-FID-MS, enabled discrimination of brandy samples based on differences in plum varieties, pH of plum mash, and addition of selected yeast or enzymes during fermentation. The correlation of brandy GC-FID-MS profiles with their sensory properties was achieved by OPLS multivariate analysis. Proposed workflow confirmed the potential of GC-FID-MS in combination with multivariate data analysis that can be applied to assess the plum brandy quality.

Characterization of Phenolic Compounds, Vitamin E and Fatty Acids from Monovarietal Virgin Olive Oils of "Picholine marocaine" Cultivar.

Olive oil is an important product in the Mediterranean diet, due to its health benefits and sensorial characteristics. Picholine marocaine is the most cultivated variety in Morocco. The present research aims to evaluate the phenolic compounds, vitamin E and fatty acids of commercial Picholine marocaine virgin olive oils (VOOs) from five different North Moroccan provinces (Chefchaouen, Taounate, Errachidia, Beni Mellal and Taza), using HPLC-photodiode array (PDA)/electrospray ionization (ESI)-MS, normal phase (NP)-HPLC/ fluorescence detector (FLD) and GC-flame ionization detector (FID)/MS, respectively. The obtained results showed an average content of 130.0 mg kg-1 of secoiridoids (oleuropein aglycone, 10-hydroxy-oleuropein aglycone and ligstroside aglycone, oleocanthal and oleacein), 108.1 mg kg-1 of phenolic alcohols (tyrosol and hydroxytyrosol), 34.7 mg kg-1 of phenolic acids (caffeic acid, ferulic acid and elenolic acid), and 8.24 mg kg-1 of flavonoids (luteolin, luteolin glucoside, apigenin). With regard to vitamin E, α-tocopherol was the most abundant vitamin E (57.9 mg kg-1), followed by α-tocotrienol (2.5 mg kg-1), γ-tocopherol (4.5 mg kg-1) and ß-tocopherol (1.9 mg kg-1), while δ-tocopherol was not detected. Moreover, 14 fatty acids were found and, among them, oleic acid (76.1%), linoleic acid (8.1%) palmitic acid (8.7%) and stearic acid (2.5%) were the major fatty acids detected. Finally, heat map and principal component analysis allowed us to classify the studied provinces in terms of VOO chemical composition: Chefchaouen (tyrosol and hydroxytyrosol), Taounate (oleuropein aglycone), Errachidia (ferulic acid, w-3 and w-6), Beni Mellal (oleocanthal) and Taza (luteolin and oleic acid).

Identification of Fatty Acid, Lipid and Polyphenol Compounds from Prunus armeniaca L. Kernel Extracts.

Apart from its essential oil, Prunus armeniaca L. kernel extract has received only scarce attention. The present study aimed to describe the lipid and polyphenolic composition of the dichloromethane, chloroform, ethyl acetate, and ethanol extracts on the basis of hot extraction, performing analysis by gas chromatography and high-performance liquid chromatography coupled with mass spectrometry. A total of 6 diacylglycerols (DAGs) and 18 triacylglycerols (TAGs) were detected as being present in all extracts, with the predominance of OLL (dilinoleyl-olein), OOL (dioleoyl-linolein), and OOO (triolein), with percentages ranging from 19.0-32.8%, 20.3-23.6%, and 12.1-20.1%, respectively. In further detail, the extraction with ethyl acetate (medium polarity solvent) gave the highest signal for all peaks, followed by chloroform and dichloromethane (more apolar solvent), while the extraction with ethanol (polar solvent) was the least efficient. Ethanol showed very poor signal for the most saturated TAGs, while dichloromethane showed the lowest percentages of DAGs. Accordingly, the screening of the total fatty acid composition revealed the lowest percentage of linoleic acid (C18:2n6) in the dichloromethane extract, which instead contained the highest amount (greater than 60%) of oleic acid (C18:1n9). Polyphenolic compounds with pharmacological effects (anti-tumor, anti-coagulant, and inflammatory), such as coumarin derivative and amygdalin, occurred at a higher amount in ethyl acetate and ethanol extracts.

Formation and Emissions of Volatile Organic Compounds from Homo-PP and Co-PP Resins during Manufacturing Process and Accelerated Photoaging Degradation.

Volatile organic compounds (VOCs) from polypropylene (PP) seriously restricts the application of PP in an automotive field. Herein, the traceability of VOCs from PP resins during manufacturing process and accelerated photoaging degradation was clarified on basis of an accurate characterization method of key VOCs. The influence of PP structures on changing the accelerated photoaging degradation on the VOCs was systematic. The VOCs were identified by means of Gas chromatography (GC) coupled with both a hydrogen flame ion detector (FID) and a mass spectrometry detector (MSD). Results showed that both the molecular structure of PP and the manufacturing process affected the species and contents of VOCs. In addition, the photoaging degradation of PP resulted in a large number of new emerged volatile carbonyl compounds. Our work proposed a possible VOC formation mechanism during the manufacturing and photoaging process. VOCs from PP resins were originated from oligomers and chain random scission during thermomechanical degradation. However, ß scission of alkoxy radical and Norrish tape I reactions of ketones via intermediate transition were probably the main VOCs formation routes towards PP during photoaging degradation. This work could provide scientific knowledge on both the accurate traceability of VOCs emissions and new technology for development of low-VOCs PP composites for vehicle.

Diagnostic Potential of FT-IR Fingerprinting in Botanical Origin Evaluation of Laurus nobilis L. Essential Oil is Supported by GC-FID-MS Data.

The last years, non-targeted fingerprinting by Fourier-transform infrared (FT-IR) spectroscopy has gained popularity as an alternative to classical gas chromatography (GC)-based methods because it may allow fast, green, non-destructive and cost-effective assessment of quality of essential oils (EOs) from single plant species. As the relevant studies for Laurus nobilis L. (bay laurel) EO are limited, the present one aimed at exploring the diagnostic potential of FT-IR fingerprinting for the identification of its botanical integrity. A reference spectroscopic dataset of 97 bay laurel EOs containing meaningful information about the intra-species variation was developed via principal component analysis (PCA). This dataset was used to train a one-class model via soft independent modelling class analogy (SIMCA). The model was challenged against commercial bay laurel and non-bay laurel EOs of non-traceable production history. Overall, the diagnostic importance of spectral bands at 3060, 1380-1360, 1150 and 1138 cm-1 was assessed using GC-FID-MS data. The findings support the introduction of FT-IR as a green analytical technique in the quality control of these often mislabeled and/or adulterated precious products. Continuous evaluation of the model performance against newly acquired authentic EOs from all producing regions is needed to ensure validity over time.

Volatile Constituents and Biological Properties of Essential Oils from Aerial Parts of Gentiana gelida BIEB.

This work reports the chemical composition, antimicrobial and antioxidant activities of essential oils from the aerial parts of Gentiana gelida BIEB. for the first time in literature. The oils from the aerial parts (flower, leaf and stem) were obtained by Clevenger-type apparatus and characterized by GC-FID and GC-MS. While tricosane (21.67%) was the main component of flower oil, hexadecanoic acid was the most abundant component of leaf and stem oils in ratios 26.46% and 31.89%, respectively. Additionally, all essential oils of G. gelida were investigated for their antimicrobial activity against eight Gram negative bacteria, four Gram positive bacteria and five fungi, using agar dilution method and antioxidant activities by using 2,2-diphenyl-1-picrylhydrazyl radical scavenging and Folin-Ciocalteu assays. The flower oil of G. gelida showed stronger antimicrobial and antioxidant activities than those of stem and leaf. The amount of total phenolic content and scavenging activity of the flower oil were found 525.35±8.24 mg GAE/L and 49.30±1.25%, respectively.

First characterization of Pompia intrea candied fruit: The headspace chemical profile, polar extract composition and its biological activities.

Extracts obtained from Pompia intrea (PI), a traditional candied fruit whose main ingredient is the pompia fruit (Citrus monstruosa L.) were evaluated for the first time. Volatile compounds were evaluated by headspace solid-phase microextraction (HS-SPME) followed by GC-FID/MS analyses. Polar compounds were identified by high-performance liquid chromatography coupled with electrospray mass spectrometry LC-ESI-Orbitrap-MS/MS and quantified by liquid chromatography coupled with ultraviolet/visible detection (LC-DAD). The antioxidant activity of these extracts was tested using the FRAP, CUPRAC, ABTS•+ and DPPH● assays. Moreover, their ability to protect intestinal cells against lipid peroxidation was studied. The HS-SPME GC-FID/MS confirmed the presence of typical molecules originating from the fruit (mainly terpenes, but particularly limonene). The LC-DAD and LC-ESI-(HR)MSn profiles showed high levels of neohesperidin (45.7 ±â€¯11.1 mg/L) and 5-(hydroxymethyl)furfural (40.8 ±â€¯23.5 mg/L). The results showed that the PI extracts contained high levels of total phenols and exhibited considerable antioxidant activity, which was significantly correlated to the presence of specific compounds such as neoeriocitrin and neohesperidin. Furthermore, pretreatments with different concentrations of PI extracts preserved enterocytes from oxidative damage by scavenging reactive oxygen species, thus counteracting lipid peroxidation. This study suggests that consumption of PI could provide intake of compounds with ascertained biological activity.

Chemical composition and antimicrobial activity of the essential oils from flowers and leaves of Grindelia integrifolia DC.

Essential oils from flowers and leaves of Grindelia integrifolia DC. were investigated for the first time in terms of chemical composition and antimicrobial activity. The GC-FID/MS analysis allowed for the identification of 58 and 72 volatiles, comprising 92.4 and 90.1% of the oils, respectively. The major components of the flower oil were α-pinene (34.9%) and limonene (13.1%), while myrcene (16.9%), spathulenol (12.3%), ß-eudesmol (11.9%) and limonene (10.1%) dominated among the leaf volatiles. The antimicrobial activity, evaluated against 12 selected bacteria and fungus, was found moderate, with the strongest effect of both oils observed against C. albicans (MIC = MBC: 0.63 and 0.31 mg/mL for flower and leaf oil, respectively).

Interspecies Developmental Differences in Metabonomic Phenotypes of Lycium ruthenicum and L. barbarum Fruits.

Fruits of Lycium ruthenicum (LR) and L. barbarum (LB) in Solanaceae family contain abundant bioactive metabolites used widely as functional food and natural medicine. To characterize the fruit developmental molecular phenotypes, we comprehensively analyzed metabolite composition of both Lycium fruits at three developmental stages using the combined NMR, liquid chromatography-tandem mass spectrometry, and gas chromatography-flame ionization detector/mass spectrometry methods. The metabonomes of these fruits were dominated by over 90 metabolites including sugars, amino acids, tricarboxylic acid (TCA) cycle intermediates, fatty acids, choline metabolites, and shikimate-mediated plant secondary metabolites. Metabolic phenotypes of two species differed significantly at all three developmental stages; LB fruits contained significantly more sugars and amino acids but less TCA cycle intermediates, fatty acids, and secondary metabolites than LR. Interspecies differences for fatty acid levels were much greater after color-breaking than precolor-breaking. Furthermore, LR fruits contained more osmolytes than LB fruits indicating different osmoregulation requirements for these fruits during development. Significant differences were also present in biosynthesis of shikimate-mediated plant secondary metabolites in LR and LB. These findings provided essential metabolic information for plant physiology of these  Lycium species and their utilizations demonstrating the usefulness of this metabonomic phenotyping approach for studying fundamental biochemistry of the plant development.

Dynamic metabolic responses of brown planthoppers towards susceptible and resistant rice plants.

Brown planthopper (Nilaparvata lugens Stål, BPH) causes huge economic losses in rice-growing regions, and new strategies for combating BPH are required. To understand how BPHs respond towards BPH-resistant plants, we systematically analysed the metabolic differences between BPHs feeding on the resistant and susceptible plants using NMR and GC-FID/MS. We also measured the expression of some related genes involving glycolysis and biosyntheses of trehalose, amino acids, chitin and fatty acids using real-time PCR. BPH metabonome was dominated by more than 60 metabolites including fatty acids, amino acids, carbohydrates, nucleosides/nucleotides and TCA cycle intermediates. After initial 12 h, BPHs feeding on the resistant plants had lower levels of amino acids, glucose, fatty acids and TCA cycle intermediates than on the susceptible ones. The levels of these metabolites recovered after 24 h feeding. This accompanied with increased level in trehalose, choline metabolites and nucleosides/nucleotides compared with BPH feeding on the susceptible plants. Decreased levels of BPH metabolites at the early feeding probably resulted from less BPH uptakes of sap from resistant plants and recovery of BPH metabolites at the later stage probably resulted from their adaptation to the adverse environment with their increased hopping frequency to ingest more sap together with contributions from yeast-like symbionts in BPHs. Throughout 96 h, BPH feeding on the resistant plants showed significant up-regulation of chitin synthase catalysing biosynthesis of chitin for insect exoskeleton, peritrophic membrane lining gut and tracheae. These findings provided useful metabolic information for understanding the BPH-rice interactions and perhaps for developing new BPH-combating strategies.

Screening of Satureja subspicata Vis. Honey by HPLC-DAD, GC-FID/MS and UV/VIS: Prephenate Derivatives as Biomarkers.

The samples of Satureja subspicata Vis. honey were confirmed to be unifloral by melissopalynological analysis with the characteristic pollen share from 36% to 71%. Bioprospecting of the samples was performed by HPLC-DAD, GC-FID/MS, and UV/VIS. Prephenate derivatives were shown to be dominant by the HPLC-DAD analysis, particularly phenylalanine (167.8 mg/kg) and methyl syringate (MSYR, 114.1 mg/kg), followed by tyrosine and benzoic acid. Higher amounts of MSYR (3-4 times) can be pointed out for distinguishing S. subspicata Vis. honey from other Satureja spp. honey types. GC-FID/MS analysis of ultrasonic solvent extracts of the samples revealed MSYR (46.68%, solvent pentane/Et2O 1:2 (v/v); 52.98%, solvent CH2Cl2) and minor abundance of other volatile prephenate derivatives, as well as higher aliphatic compounds characteristic of the comb environment. Two combined extracts (according to the solvents) of all samples were evaluated for their antioxidant properties by FRAP and DPPH assay; the combined extracts demonstrated higher activity (at lower concentrations) in comparison with the average honey sample. UV/VIS analysis of the samples was applied for determination of CIE Lab colour coordinates, total phenolics (425.38 mg GAE/kg), and antioxidant properties (4.26 mmol Fe(2+)/kg (FRAP assay) and 0.8 mmol TEAC/kg (DDPH assay)).