Effect of phosphorus concentration of the nutrient solution on the volatile constituents of leaves and bracts of Origanum dictamnus

The chemical composition of the essential oils obtained from the leaves and bracts of hydroponically cultivated Origanum dictamnus were analyzed by GC-MS techniques. Three different concentrations of phosphorus (5, 30, and 60 mg/L) in the nutrient solution were used for the cultivation, using the nutrient film technique (NFT). A total of 46 different compounds were identified and significant differences (qualitative and quantitative) were observed between the samples. Carvacrol and p-cymene were identified as the main compounds in all samples analyzed, whereas thymoquinone was found in higher percentage in the leaves than in bracts. The essential oils were tested for their antibacterial activity against Gram-positive and Gram-negative bacteria. The oils obtained from the bracts were found to be more active. The results obtained from GC-MS analyses were submitted to chemometric analysis.     

Effect of solution conductivity on the volatile constituents of Origanum dictamnus L. in nutrient film culture

The chemical composition of the essential oils obtained from leaves and bracts of hydroponically cultivated Origanum dictamnus L. (Cretan dittany), growing under various electrical conductivity (EC) levels (2.0, 4.0, and 6.0 mS/cm), was studied, using the nutrient film technique (NFT). The analysis of the essential oil content was achieved by GC-MS technique, and totals of 41 and 38 different compounds were identified in both cases of large-leaved and narrow-leaved samples of leaves and bracts, respectively. Differences in the composition content and of the percentage of each of the constituents in the two studied samples (i.e., large-leaved and narrow-leaved) and within the essential oils of leaves and bracts in both samples were observed. Carvacrol and p-cymene were identified as the main constituents in all essential oils, whereas thymoquinone was found in higher percentage in the essential oils of large-leaved than in narrow-leaved plants. The results obtained from GC-MS analysis were submitted to chemometric analysis, and a phenotypic similarity of the essential oils of narrow-leaved O. dictamnus was observed, whereas the essential oils of large-leaved O. dictamnus showed two separate subgroups.     

Composition, enantiomeric distribution, and antibacterial activity of the essential oil of Achillea ligustica All. from Corsica

The essential oil of Achillea ligustica from Corsica was investigated by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). A total of 82 compounds representing 94.0% of the oil were tentatively identified. The main constituents were the camphane derivatives, representing >30% (camphor, 21.3%; borneol, 6.2%; bornyl acetate, 3.5%) of the whole oil, and santolina alcohol (19.3%). The enantiomeric distribution of 8 chiral constituents was determined by GC-MS using two enantioselective stationary phases (DIME-beta-CD and Lipodex-E). Racemic santolina alcohol, required for optimization of the enantioselective GC conditions, was prepared by an original two-step synthesis from 2,5-dimethylhexa-2,4-diene. The whole essential oil was tested for its antibacterial activity against a wide range of bacteria using a paper disk method. The results show a promising activity against Streptomyces species.     

Identification of the volatile component(s) causing the characteristic foxy odor in various cultivars of Fritillaria imperialis L. (Liliaceae)

To identify the component(s) causing the foxy odor, characteristic for some Fritillaria imperialis cultivars, the headspace of flower bulbs was analyzed using gas chromatography-olfactometry (GC-O) and GC-mass spectrometry (GC-MS). Six Fritillaria species and cultivars were selected as follows: F. imperialis cv. Premier (very strong foxy odor), F. imperialis cv. Lutea (strong foxy odor), F. imperialis ssp. Inodora (no odor), Fritillaria eduardii (weak mousy odor), Fritillaria raddeana (no odor), and an F1 of F. imperialis Lutea x Inodora (weak foxy odor). Volatiles from these flower bulbs were accumulated on Tenax and injected into the GC by thermodesorption. The majority of the volatiles consisted of low molecular weight aliphatic compounds. GC-O revealed that the foxy odor was caused by a single component, identified as 3-methyl-2-butene-1-thiol on the basis of smell in GC-O analyses (two GC columns), mass spectra, and retention times. Chemical identification was substantiated by GC-O and GC-MS of an authentic standard of 3-methyl-2-butene-1-thiol, prepared by organic synthesis.     

Composition and antifungal activity on soil-borne pathogens of the essential oil of Salvia sclarea from Greece

The hydrodistilled essential oils of the aerial parts of wild-growing Salvia sclarea originated from two localities in Greece were analyzed by GC-MS. Sixty-six compounds, representing 93.26-98.19% of the oils, were identified. Linalyl acetate (19.75-31.05%), linalool (18.46-30.43%), geranyl acetate (4.45-12.1%), and alpha-terpineol (5.08-7.56%) were the main components. The antifungal activity of the oil of one locality and of the main components, linalyl acetate and linalool, was evaluated in vitro against three soil-borne pathogens.     

Changes in headspace volatile concentrations of coffee brews caused by the roasting process and the brewing procedure

Headspace-solid-phase microextraction technique (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) were used to characterize the aroma compounds of coffee brews from commercial conventional and torrefacto roasted coffee prepared by filter coffeemaker and espresso machine. A total of 47 volatile compounds were identified and quantified. Principal component analysis (PCA) was applied to differentiate coffee brew samples by volatile compounds. Conventional and torrefacto roasted coffee brews were separated successfully by principal component 1 (68.5% of variance), and filter and espresso ones were separated by principal component 2 (19.5% of variance). By GC olfactometry, a total of 34 aroma compounds have been perceived at least in half of the coffee extracts and among them 28 were identified, among which octanal was identified for the first time as a contributor to coffee brew aroma.     

Thermal degradation of sulforaphane in aqueous solution.

Sulforaphane, a cancer chemopreventive agent identified from broccoli, was degraded in an aqueous solution at 50 and 100 degrees C. The reaction mixtures were extracted with methylene chloride and analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). Dimethyl disulfide, S-methyl methylthiosulfinate, S-methyl methylthiosulfonate, methyl (methylthio)methyl disulfide, 1,2,4-trithiolane, 4-isothiocyanato-1-(methylthio)-1-butene, and 3-butenyl isothiocyanate were identified as volatile decomposition products. After methylene chloride extraction, the aqueous layer was dried and silica gel column chromatography was used to separate and purify the nonvolatile decomposition products. The major thermal degradation compound was determined by (1)H NMR, (13)C NMR, and FAB-MS as N, N'-di(4-methylsulfinyl)butyl thiourea. A possible mechanism for the formation of these products is proposed.     

Multiresidue determination of pesticides in malt beverages by capillary gas chromatography with mass spectrometry and selected ion monitoring

A method was developed to determine pesticides in malt beverages using solid phase extraction on a polymeric cartridge and sample cleanup with a MgSO4-topped aminopropyl cartridge, followed by capillary gas chromatography with electron impact mass spectrometry in the selected ion monitoring mode [GC-MS(SIM)]. Three GC injections were required to analyze and identify organophosphate, organohalogen, and organonitrogen pesticides. The pesticides were identified by the retention times of peaks of the target ion and qualifier-to-target ion ratios. GC detection limits for most of the pesticides were 5-10 ng/mL, and linearity was determined from 50 to 5000 ng/mL. Fortification studies were performed at 10 ng/mL for three malt beverages that differ in properties such as alcohol content, solids, and appearance. The recoveries from the three malt beverages were greater than 70% for 85 of the 142 pesticides (including isomers) studied. The data showed that the different malt beverage matrixes had no significant effect on the recoveries. This method was then applied to the screening and analysis of malt beverages for pesticides, resulting in the detection of the insectide carbaryl and the fungicide dimethomorph in real samples. The study indicates that pesticide levels in malt beverages are significantly lower than the tolerance levels set by the United States Environmental Protection Agency for malt beverage starting ingredients. The use of the extraction/cleanup procedure and analysis by GC-MS(SIM) proved effective in screening malt beverages for a wide variety of pesticides.     

(E)-Methylisoeugenol and elemicin: antibacterial components of Daucus carota L. essential oil against Campylobacter jejuni

The essential oil of wild Daucus carota L. obtained from aerial parts at the end of the flowering stage (DCEO) was reported as antimicrobial against the human enteropathogen Campylobacter jejuni. The aim of the present study was to extend this analysis to other Campylobacter species and to identify the active compounds of the essential oil, subjected to GC, GC-MS, and (13)C NMR analysis. A minimum inhibitory concentration assay was used to quantify the antimicrobial activity of DCEO and the major components, isolated on column chromatography. Growth of all the C. jejuni, Campylobacter coli, and Campylobacter lari strains tested, including one multidrug resistant C. jejuni, was inhibited to the same extent by DCEO. Molecules that were responsible for the antibacterial activity were identified as (E)-methylisoeugenol and elemicin. Moreover, the use of structural analogues of these compounds allowed us to identify important features that may account for the activity.     

Pathways for the hydrolysis of phorate: product studies by (31)P NMR and GC-MS

A new intramolecular mechanism is proposed for the hydrolysis of phorate. (31)P NMR was used to study the formation of P-containing products of phorate hydrolysis in situ. When hydrolysis was followed by (31)P NMR, a dominant P-containing product was found and was identified to be diethyl dithiophosphate using methylation and GC-MS. Combining the data from phorate hydrolysis at three different temperatures, thermodynamic parameters were calculated. The contributions of various possible pathways to phorate hydrolysis are discussed.     

Volatile metabolites from Salvia fruticosa as antifungal agents in soilborne pathogens

The volatile metabolites of Salvia fruticosa plants, growing wild in 15 localities scattered across Greece, were analyzed by means of GC and GC-MS. The essential oil content ranged from 0.69 to 4.68%, and the results of the analyses showed a noticeable variation in the amounts of the five main components [1,8-cineole, alpha-thujone, beta-thujone, camphor, and (E)-caryophyllene]. The antifungal activities of the essential oils from two localities, belonging in two different groups of cluster and principal component analysis, and their main components (1,8-cineole and camphor) were evaluated in vitro against five phytopathogenic fungi. Both oils were slightly effective against Fusarium oxysporum f. sp. dianthi and Fusarium proliferatum, whereas against Rhizoctonia solani, Sclerotinia sclerotiorum, and Fusarium solani f. sp. cucurbitae the oils exhibited high antifungal activities.     

不同营养液浓度对温室盆栽黄瓜产量与品质的影响

营养液浓度与供液方式会影响温室黄瓜的产量与品质。本文通过盆栽试验,以山崎黄瓜专用营养液配方标准浓度1S为基准,研究了负水头供水控水盆栽装置供液条件下 1/2S、3/4S、1S、1S 4种营养液浓度以及常规浇灌1S（CK）营养液浓度对温室盆栽基质栽培黄瓜产量与品质的影响。结果表明, 地上部干重和产量与营养液浓度成显著正相关关系; 1S处理产量与地上部干重显著大于1S (CK)处理,但营养液生产效率差异不显著; 黄瓜整体品质随生育进程而提高,采收初期果实品质整体指标各处理差异较大,1S处理的较高; 采收中期1S与1S处理的较高,而采收末期各处理整体品质差异较小,1/2S与1S（CK）处理的相对较高; 其中1S（CK）处理各采收时期果实硝酸盐含量明显高于1S处理,而其它各指标两者无显著差异。负水头供水控水盆栽装置供液方式与1S营养液浓度处理是一种较好的供液方式与供液浓度。同时,适当提高黄瓜生育前期与降低生育末期营养液浓度能提高黄瓜的整体品质。     

Analysis of glycated and ascorbylated proteins by gas chromatography-mass spectrometry

Proteins or poly-L-lysine which were incubated in the presence of ascorbic acid, dehydroascorbic acid (ascorbylation), or various sugars (glycation) were analyzed by gas chromatography-mass spectrometry (GC-MS). To also detect more labile reaction products, the Maillard modified proteins or poly-L-lysine were enzymatically hydrolyzed and reacted with N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide to form the N(O)-tert-butyldimethylsilyl (tBDMS) derivatives prior to GC analysis. Under these conditions, the known Maillard products N (epsilon)-(carboxymethyl)lysine (1), oxalic acid mono-N (epsilon)-lysinylamide (2), and N (epsilon)-(carboxyethyl)lysine (3) could be simultaneously detected and quantified in glycated and ascorbylated proteins. Additionally, N (epsilon)-(1-carboxy-3-hydroxypropyl)-L-lysine (4) was identified for the first time as a Maillard product of proteins. Under the conditions applied here, 4 was found only in ascorbylated proteins or poly-L-lysine, but not in glycated proteins. Maillard-modified poly-L-lysine was further subjected to high-performance liquid chromatography (HPLC) analysis after enzymatic hydrolysis and formation of the phenyl isothiocyanate derivatized amino acids. Using this method, N (epsilon)-formyl-L-lysine (5), which cannot be distinguished from 2 by GC-MS analysis, was identified for the first time as a glycation product. Compound 5 is mainly formed from ribose, lactose, and fructose. The indicated Maillard products were quantified in beta-lactoglobulin (GC-MS) or poly-L-lysine (HPLC) which were glycated or ascorbylated using different precursors.     

玉米不同生育阶段养分效应评价方法研究

了解作物养分效应机制是提高作物养分利用效率的重要基础。本文以玉米品种"农华101"为试验材料, 进行不同播期、密度、肥料试验, 记录了生育时期的日均温, 并对玉米不同生育时期叶片及其他器官中氮、磷、钾元素含量进行了测定, 然后基于改进后的BLUP方法, 在考虑植株干物质日均积累量与自身效应、环境效应关系的基础上, 引入群体效应和温度效应, 探讨并建立了玉米不同生育阶段养分效应评价方法。在此基础上, 进一步对养分效应评价效果进行分析。结果表明: 干物质日均积累量理论值与实际值的相关性r值为0.72~0.99; 各生育阶段配对t检验的α值均大于0.05, 各生育阶段的干物质日均积累量的理论值和实测值差异均不显著(P>0.05)。研究结果表明, 用建立的玉米不同生育阶段的养分效应评价方法得到的各养分特征效应值存在较大差异, 其中: 三叶期到拔节期各养分效应值为0~0.58, 拔节期到大口期为 0.43~2.57, 大口期到吐丝期为 0.45~4.58, 吐丝期到成熟期为 0.86~4.71。综上, 利用改进后的BLUP法提出的养分效应评价方法对玉米各阶段养分效应的评价结果具有一定的指导意义, 该方法可作为玉米养分效应评价的参考手段。     

高浓度营养液对黄瓜和番茄下胚轴徒长的抑制作用

【目的】黄瓜和番茄是我国主栽蔬菜种类,育苗过程中容易遭遇高温、高湿、弱光等不良环境,导致幼苗下胚轴徒长,严重影响后期丰产性。在控制幼苗徒长的实际操作中,利用植物生长调节剂、机械刺激、补光、温度调节、水分控制等调控方法容易受到多种因素影响而效果不佳。本文研究高浓度营养液浓度对黄瓜和番茄幼苗下胚轴徒长的抑制作用,以期提出一种有效制御幼苗徒长的方法。【方法】试验以Hoagland标准营养液配方为基础浓度（设为1.0C）,通过成比例增减大量元素组分用量而不改变微量元素组分用量,组成0.5C、2.5C、5.0C、7.5C、10.0C和12.5C 6个浓度。以0.5C为对照,在日光温室条件下分别对黄瓜和番茄幼苗进行灌施处理。待幼苗生长至子叶平展期时,测定黄瓜和番茄幼苗形态及生长指标,研究营养液浓度对幼苗下胚轴细胞长度、生长速率及内源激素含量的影响;随后对幼苗进行0.5C低浓度营养液的恢复生长处理,待幼苗生长至第一真叶平展期时,再次进行幼苗形态及生长指标的测定,从而确定高浓度营养液对黄瓜和番茄下胚轴徒长的抑制效果及机制,并确定最适合制御幼苗徒长的营养液浓度。【结果】6种浓度营养液对黄瓜和番茄幼苗下胚轴徒长的影响结果为: 1）高浓度营养液显著提高了基质EC值（r=0.99）,黄瓜和番茄幼苗在子叶平展期其下胚轴生长受到明显抑制,下胚轴长度、绝对生长速率和含水量均呈下降趋势,下胚轴皮层薄壁细胞轴/径向生长也受到影响。与对照相比,10.0C营养液处理下黄瓜和番茄幼苗下胚轴皮层薄壁细胞缩短为49%和48%。2）随着营养液浓度的增加,黄瓜和番茄下胚轴内源激素含量发生显著变化,其中赤霉酸（GA3）、玉米素核苷（ZR）含量呈降低趋势,而脱落酸（ABA）含量呈升高趋势,且ABA含量与下胚轴长度呈极显著负相关关系（P＜0.01）。生长素（IAA）含量在不同浓度营养液处理下呈现区位性变化特征。3）在幼苗子叶平展期重新灌施0.5C浓度的营养液,对5.0C和7.5C处理下生长的幼苗均有恢复生长的作用,且幼苗株高/茎粗比明显优于对照和其它处理,该浓度可望有效避免幼苗徒长。【结论】高营浓度养液通过改变幼苗内源激素的动态平衡,特别是促进ABA的合成和积累,从而抑制幼苗下胚轴皮层细胞伸长生长,有效制御幼苗徒长。灌施高浓度营养液对黄瓜、番茄幼苗下胚轴伸长的抑制作用可以通过降低营养液浓度而得到解除,这种防治幼苗徒长的操作方法简便易行,具有潜在的应用前景,但在不同品种蔬菜幼苗生长过程中,最优化的营养液施用浓度及其影响机制尚需进一步研究分析。     

Analysis of volatiles from Spanish honeys by solid-phase microextraction and gas chromatography-mass spectrometry

Headspace solid-phase microextraction (SPME), followed by gas chromatography (GC)-mass spectrometry (MS) determination, has been used for the analysis of honey volatiles. Two SPME fibers were employed to study the composition of volatiles from various types of Spanish honeys. The best results were obtained with the Carboxen/PDMS fiber, using a homogenization time of 1 h at 70 degrees C and a sampling period of 30 min. A total of 35 compounds were detected, most of them identified by GC-MS and quantified using external standards. Differences in the composition of honey volatiles were obtained, and these results allowed the differentiation of honeys. However, further studies are necessary to confirm the utility of this technique as an alternative tool for the characterization of the floral origin of honeys.     

Volatile compounds of Psidium salutare (H.B.K.) Berg. fruit

Volatile compounds were isolated from Psidium salutare fruits by simultaneous steam distillation-solvent extraction according to the Likens-Nickerson procedure. Compounds were identified by capillary GC and GC-MS. One hundred and fifty compounds were identified in the aroma concentrate, from which limonene, myrcene, and alpha-pinene were found to be the major constituents in the fruit.     

Characterization of volatiles in strawberry guava (Psidium cattleianum Sabine) fruit.

Volatile compounds were isolated from strawberry guava fruit by simultaneous steam distillation-solvent extraction according to Likens-Nickerson. Compounds were identified by capillary GC-MS and sensorially characterized by sniffing GC. Two hundred and four compounds were identified in the aroma concentrate, of which ethanol, alpha-pinene, (Z)-3-hexenol, (E)-beta-caryophyllene, and hexadecanoic acid were found to be the major constituents. The presence of many aliphatic esters and terpenic compounds is thought to contribute to the unique flavor of the strawberry guava fruit.