The Chemical Components of Essential Oils from the Leaves of 110 Species and Cultivars of Citrus Plants

Seventy-two chemical components of essential oils from the leaves of 110 species and cultivars of Citrus were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Among the plants analyzed, there are 3 species in papeda, 12 species and cultivars in Osmocitrus, 18 cultivars in C. aurantium L., 15 cultivars in C. sinensis Osbeck, 16 species and cultivars in Citrophorum, 16 species and cuhivars in Cephalocitrus, 30 species and cultivars in Acrumen. As resources of essential oils, some valuable plants were found such as Citrus hystrix D. C., C. junos (Sieb.) Tan. cv. Xiecheng, C. junos (Sieb.) Tan. cv. Luohancheng and C. tankan Hayata. Our study has provided systematic data of the chemical components of the essential oils for the taxonomic work of Citrus plants.     

Identification and quantitative analysis of beta-sitosterol oxides in vegetable oils by capillary gas chromatography-mass spectrometry

As vegetable oils and phytosterol-enriched spreads are marketed for frying food or cooking purposes, temperature is one of the most important factors leading to the formation of phytosterol oxides in food matrix. A methodology based on saponification, organic solvent extraction, solid-phase extraction (SPE), followed by mass spectrometric identification and quantitation of beta-sitosterol oxides using capillary gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode was developed and characterized. Relative response factors of six beta-sitosterol oxides, including 7alpha-hydroxy, 7beta-hydroxy, 5,6alpha-epoxy, 5,6beta-epoxy, 7-keto, and 5alpha,6beta-dihydroxysitosterol, were calculated against authentic standards of 19-hydroxycholesterol or cholestanol. Linear calibration data, limit of detection, and sample recoveries during analytical process. Recoveries of these oxidation compounds in spiked samples ranged from 88 to 115%, while relative standard derivation (R.S.D.) values were below 10% in most cases. The analytical method was applied to quantify beta-sitosterol oxides formed in thermal-oxidized vegetable oils which were heated at different temperatures and for varying time periods. Sitosterol oxidation is strikingly higher in sunflower oil relative to olive oil under all conditions of temperature and heating time.     

Wood essential oils of two endemic trees from New Caledonia: Callitris sulcata (Parl.) Schltr. and Callitris neocaledonica Dummer

The essential oils obtained by hydrodistillation of pieces of dead trunks of Callitris sulcata (Parlatore) Schlechter and Callitris neocaledonica Dummer were investigated by gas chromatography, mass spectrometry and NMR spectroscopy. Analyses evidenced the presence of rare natural compounds: both essential oils are exclusively sesquiterpenic with nevertheless remarkable difference: C. sulcata essential oil was dominated by β-barbatene and thujopsene while C. neocaledonica was characterized by high levels of guaiane- and eudesmane-type structures (eudesmols, guaiol and related components). The biochemical correlations between the major components of each species are discussed and the relationship between the two species is commented.     

液质联用多反应监测法定量目标多肽或蛋白质

为建立优化的血浆内源性多肽提取方法,并且构建目标多肽和蛋白质的质谱定量方 法,本研究考察了超滤法、有机溶剂沉淀法和固相萃取法对血浆内源性多肽的提取效果 ,并通过Tricine-SDS-PAGE对提取效果进行比较.通过液相色谱串联质谱多反应监测 （MRM）分析,建立了多肽标准品ESAT-6定量方法,并将ESAT-6定量建立的液相色谱和质谱条件应用于蛋白质的定量,对多肽和蛋白质MRM定量的标准曲线进行了考 察.Tricine-SDS-PAGE结果表明,乙腈沉淀法是最佳的血浆内源性多肽提取方法,低分子量的多肽可以得到很好的富集,且能有效地去除高分子蛋白质的污染.液相色谱串联 质谱MRM法检测血浆内提取的多肽,标准曲线的线性较好,相关系数为0.999.另外,采 用MRM法对胶内分离的蛋白质进行定量,标准曲线的线性相关系数为0.995.综上所述, 本研究构建了一种简单有效的血浆多肽提取方法,通过液质联用MRM法成功地实现了目标多肽和蛋白质定量测定.该定量方法可以推广应用于复杂样品中的多肽和蛋白质的定 量分析.     

A simplified procedure for GC/C/IRMS analysis of underivatized 19-norandrosterone in urine following HPLC purification

Nandrolone and/or its precursors are included in the World Anti-doping Agency (WADA) list of forbidden substances and methods and as such their use is banned in sport. 19-Norandrosterone (19-NA) the main metabolite of these compounds can also be produced endogenously. The need to establish the origin of 19-NA in human urine samples obliges the antidoping laboratories to use isotope ratio mass spectrometry (IRMS) coupled to gas chromatography (GC/C/IRMS). In this work a simple liquid chromatographic method without any additional derivatization step is proposed, allowing to drastically simplify the urine pretreatment procedure, leading to extracts free of interferences permitting precise and accurate IRMS analysis. The purity of the extracts was verified by parallel analysis by gas chromatography coupled to mass spectrometry with GC conditions identical to those of the GC/C/IRMS assay. The method has been validated according to ISO17025 requirements (within assay precision of ±0.3‰ and between assay precision of ±0.4‰). The method has been tested with samples obtained after the administration of synthetic 19-norandrostenediol and samples collected during pregnancy where 19-NA is known to be produced endogenously. Twelve drugs and synthetic standards able to produce through metabolism 19-NA have shown to present δ¹³C values around −29‰ being quite homogeneous (−28.8 ± 1.5; mean ± standard deviation) while endogenously produced 19-NA has shown values comparable to other endogenous produced steroids in the range −21 to −24‰ as already reported. The efficacy of the method was tested on real samples from routine antidoping analyses.     

Authentication of feeding fats: Classification of animal fats,fish oils and recycled cooking oils

Classification of fats and oils involves the recognition of one/several markers typical of the product. The ideal marker(s) should be specific to the fat or oil. Not many chemical markers fulfill these criteria. Authenticity assessment is a difficult task, which in most cases requires the measurement of several markers and must take into account natural and technology-induced variation. The present study focuses on the identity prediction of three by-products of the fat industry (animal fats, fish oils, recycled cooking oils), which may be used for animal feeding. Their identities were predicted by their triacylglycerol fingerprints, their fatty acid fingerprints and their profiles of volatile organic compounds. Partial least square discriminant analysis allowed samples to be assigned successfully into their identity classes. Most successful were triacylglycerol and fatty acid fingerprints (both 96% correct classification). Proton transfer reaction mass spectra of the volatile compounds predicted the identity of the fats in 92% of the samples correctly.     

Evaluation of methods for total selenium determination in yeast

The selenium determination in biological materials by the classical fluorometric method (FM) is time-consuming and also hazardous, as it requires the destruction of the organic matrix samples with hot HNO₃/HClO₄ mixtures prior to analysis. Accordingly, commercial analytical laboratories are increasingly using faster instrumental methods; for sample digestion, avoid using HClO₄. Because of these procedural changes, the results obtained by commercial laboratories may be unreliable, especially for samples containing Se in organic forms. One such “difficult” substrate is Se yeast, which contains most of its Se as selenomethionine. To establish which methods for Se analysis and sample digestion are applicable, samples of Se yeast and of selenomethionine standards were sent to laboratories employing either flame atomic absorption spectrometry (FAAS), inductively coupled plasma-mass spectrometry (ICP-MS), or hydride generation atomic absorption spectrometry (HGAAS). The result were compared with those obtained by FM and non-destructive instrumental neutron activation analysis (INAA). ICP-MS, after microwave digestion of sample with HNO₃/H₂O₂, produced results within 5% of the expected values, as did those obtained by FM and INAA. With FAAS, acceptable results were obtained after digestion with HNO₃/HCl. With HGAAS, sample digestion with HNO₃/H₂O₂ produced values that were systematically elevated by about 10% and exhibited standard deviations of ≥10%. Thus, current methods of sample digestion are applicable for Se yeast analysis by ICP-MS and FAAS, but not by HGAAS.     

Composition and anti-plasmodial activities of essential oils from some Cameroonian medicinal plants

In a search for new plant-derived biologically active compounds against malaria parasites, five essential oils extracted from the Cameroonian plants Xylopia phloiodora, Pachypodanthium confine, Antidesma laciniatum, Xylopia aethiopica, and Hexalobus crispiflorus were evaluated in regard to their anti-plasmodial activity against the W2 strain of Plasmodium falciparum. The oils were obtained from the plants with 0.12, 0.13, 0.18, 0.6 and 0.1% yields (relatively to dried material weight) respectively. Analysis by gas chromatography and mass spectrometry identified mainly terpenoids, among which alpha-copaene, gamma-cadinene, delta-cadinene, alpha-cadinol, spathulenol and caryophyllene oxide were most commonly found. The five oils were active against Plasmodium falciparum in culture. The most effective was the oil of Hexalobus crispiflorus, with an IC50 of 2 microg/ml.     

枯草芽孢杆菌JA产生的脂肽类抗生素－iturin A的纯化 及电喷雾质谱鉴定

枯草芽孢杆菌JA产生的抗生素对植物病原真菌具有广谱抗性,明确抗生素的种类是进一步研究的基础.用6mol/L盐酸沉淀JA菌株的去菌体培养基,再用甲醇抽提获得抗生素的粗提物.利用反相HPLC系统,将粗提物过Diamonsil C18柱,收集有抗小麦赤霉病等病原真菌活性的化合物1、2.运用电喷雾质谱法(ESI/MS)测得其分子量分别为1042.4D和1056.5D.再利用碰撞诱导解离(CID)技术获得化合物的典型结构特征离子碎片,结果表明分子量为1042.4D的化合物一级结构为Pro-Asn-Tyr-βAA-Asn-Tyr-Asn-Gln(βAA为14个碳原子的氨基脂肪酸),属于脂iturin A.化合物1、2为相差一个亚甲基(-CH2)的iturin A同系物.研究结果提供了一种从枯草芽孢杆菌发酵液中快速分离纯化和鉴定脂肽类抗生素iturin A的新方法.     

Molecular cloning of the cDNA coding for the (R)-(+)-mandelonitrile lyase of Prunus amygdalus: temporal and spatial expression patterns in flowers and mature seeds

A gene highly expressed in the floral organs of almond (Prunus amygdalus Batsch), and coding for the cyanogenic enzyme (R)-(+)-mandelonitrile lyase (EC 4.1.2.10), has been identified and the full-length cDNA sequenced. The temporal expression pattern in maturing seeds and during floral development was analyzed by RNA blot, and the highest mRNA levels were detected in floral tissues. The spatial mRNA accumulation pattern in almond flower buds was also analyzed by in-situ hybridization. The mRNA levels were compared during seed maturation and floral development in fruit and floral samples from cultivars classified as homozygous or heterozygous for the sweet-almond trait or homozygous for the bitter trait. No correlation was found between these characteristics and levels of mandelonitrile lyase mRNA, suggesting that the presence of this protein is not the limiting factor in the production of hydrogen cyanide. Received: 3 December 1997 / Accepted: 18 April 1998     

A sesquiterpene hydrocarbon from the bogwoods of Cryptomeria japonica D. Don, presumably formed by diagenetic hydrogenation

Structure of an hitherto unknown component of the essential oils from two bogwoods of Cryptomeria japonica D. Don was determined by mass spectrometry and NMR analyses. It was identified as cadina-1(10)-ene, a new cadinane-type sesquiterpene hydrocarbon with a single double bond.     

Volatile composition and antimicrobial activity of twenty commercial frankincense essential oil samples

Trees from the genus Boswellia (Burseraceae) are traditionally used as a medicine, a fumigant, in various cosmetic formulations and in aromatherapy in several countries around the world. This plant produces a commercial oil known as frankincense which has a woody, spicy and haunting smell. Frankincense oil has several pharmacological properties, of which many elude to the anti-infective potential. Variation in the chemical composition of this oil has been reported in literature. These factors prompted an investigation to study the commercial frankincense oils from various international suppliers. Twenty essential oils were analyzed by gas chromatography coupled to mass spectrometry. Considering the major constituents, the oils were found to be qualitatively similar. However, there was immense quantitative variation for certain oil constituents. The components identified and their range in the oils include α-pinene (2.0–64.7%); α-thujene (0.3–52.4%); β-pinene (0.3–13.1%); myrcene (1.1–22.4%); sabinene (0.5–7.0%); limonene (1.3–20.4%); p-cymene (2.7–16.9%) and β-caryophyllene (0.1–10.5%). The antimicrobial activity (minimum inhibition concentration assay) of the oils was investigated against five reference test organisms and the activity ranged from 4–16 mg/ml (Staphylococcus aureus); 1.5–8.3 mg/ml (Bacillus cereus); 4.0–12.0 mg/ml (Escherichia coli); 2.0–12.8 mg/ml (Proteus vulgaris) and 5.3–12.0 mg/ml (Candida albicans).     

Variations in Essential Oil Compositions of Lavandula pubescens (Lamiaceae) Aerial Parts Growing Wild in Yemen

Lavandula pubescens Decne . is one of five Lavandula species growing wild in Yemen. The plant is used in Yemeni traditional medicine, and the essential oil tends to be rich in carvacrol. In this work, L. pubescens was collected from eight different locations in Yemen, the essential oils obtained by hydrodistillation, and the oils analyzed by gas chromatography/mass spectrometry (GC/MS). Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used to differentiate between the L. pubescens samples. The essential oils were rich in carvacrol (60.9 – 77.5%), with lesser concentrations of carvacrol methyl ether (4.0 – 11.4%), caryophyllene oxide (2.1 – 6.9%), and terpinolene (0.6 – 9.2%). The essential oil compositions in this study showed very high similarity, but it was possible to discern two separate groups based on minor components, in particular the concentrations of terpinolene, carvacrol methyl ether, m‐cymen‐8‐ol, and caryophyllene oxide.     

Targeted proteome investigation via selected reaction monitoring mass spectrometry

Due to the enormous complexity of proteomes which constitute the entirety of protein species expressed by a certain cell or tissue, proteome-wide studies performed in discovery mode are still limited in their ability to reproducibly identify and quantify all proteins present in complex biological samples. Therefore, the targeted analysis of informative subsets of the proteome has been beneficial to generate reproducible data sets across multiple samples. Here we review the repertoire of antibody- and mass spectrometry (MS) -based analytical tools which is currently available for the directed analysis of predefined sets of proteins. The topics of emphasis for this review are Selected Reaction Monitoring (SRM) mass spectrometry, emerging tools to control error rates in targeted proteomic experiments, and some representative examples of applications. The ability to cost- and time-efficiently generate specific and quantitative assays for large numbers of proteins and posttranslational modifications has the potential to greatly expand the range of targeted proteomic coverage in biological studies. This article is part of a Special Section entitled: Understanding genome regulation and genetic diversity by mass spectrometry.     

Composition and antimicrobial activity of essential oils from Centaurea sessilis and Centaurea armena

The essential oils of air-dried Centaurea sessilis and Centaurea armena obtained by hydrodistillation were analyzed by gas chromatography-mass spectrometry (GC-MS). Forty and twenty components were identified in the essential oils and the main component of these taxons was beta-eudesmol in the ratios of 12.4% and 19.3% from C. sessilis and C. armena, respectively. The antimicrobial activity of the isolated essential oil of the plants was also investigated. They showed moderate antibacterial activity against Gram-positive and Gram-negative bacteria, but no antifungal activity was observed against two yeastlike fungi.     

Tyrolobibenzyls E and F from Scorzonera humilis and distribution of caffeic acid derivatives,lignans and tyrolobibenzyls in European taxa of the subtribe Scorzonerinae (Lactuceae,Asteraceae)

A chemosystematic study of the subtribe Scorzonerinae, a subtribe of the Lactuceae tribe of the Asteraceae family was performed, using the recently discovered tyrolobibenzyls as well as lignans and caffeic acid derivatives as diagnostic characters. In addition to the known compounds two new tyrolobibenzyls (E and F) were isolated and their structures were established by mass spectrometry and 1D and 2D NMR spectroscopy. Twenty four samples from rootstocks of seventeen different Scorzonerinae taxa, comprising members of three genera (Podospermum, Scorzonera, and Tragopogon), were analyzed. Tyrolobibenzyls A (1), B (2), C (5), D (3), E (6), and F (4) were identified in crude extracts by means of HPLC retention times, on-line UV spectra and on-line MS/MS spectra. Quantification of these compounds was performed by HPLC, using 2,2-bis-(4-hydroxyphenyl)-propane as an internal standard. Tyrolobibenzyls A-F were only detected in samples from Scorzonera humilis, while chlorogenic acid and 3,5-dicaffeoylquinic acid were detected in all samples investigated. In contrast, caffeoyl tartaric acid and cichoric acid were not detectable in any member of the subtribe Scorzonerinae.     

Direct quantification of dimethylsulfoniopropionate (DMSP) with hydrophilic interaction liquid chromatography/mass spectrometry

A simple, derivatization free method for the direct determination of dimethylsulfoniopropionate (DMSP) using hydrophilic interaction liquid chromatography (HILIC)/mass spectrometry is introduced. DMSP is a zwitterionic osmolyte which is produced from marine plankton, macro algae and higher plants. Due to its central role in climate relevant geochemical processes as well as in plant physiology and chemical ecology there is a great interest in methods for its quantification. Since DMSP is labile and difficult to extract currently most protocols for quantification are based on indirect methods. Here we show that ultra performance liquid chromatography/mass spectrometry using a HILIC stationary phase is suitable for the direct quantification of DMSP from aqueous samples and microalgal extracts. The protocol requires minimal sample preparation and phytoplankton samples can be investigated after filtration of small volumes. The limit of detection is 20nM and the calibration curve is linear in the range of 60nM to 50μM. The use of [(2)H(6)]-DMSP as internal standard allows prolonged sample storage since it is transformed with the same kinetics as natural DMSP. This makes the method suitable for both laboratory and field studies.     

Use of isotope ratio mass spectrometry to detect doping with oral testosterone undecanoate: inter-individual variability of 13C/12C ratio

The metabolic effect of multiple oral testosterone undecanoate (TU) doses over 4 weeks was assessed in seven voluntary men. The protocol was designed to detect accumulation of the substance by choosing the appropriate spot urines collections time and to study the urinary clearance of the substance after weeks of treatment. Urines were analysed by a new GC/C/isotope ratio mass spectrometry (IRMS) method to establish the delta(13)C-values of testosterone metabolites (androsterone and etiocholanolone) together with an endogenous reference compound (16(5alpha)-androsten-3alpha-ol). The significant differences in inter-individual metabolism following TU intake was illustrated by large variations in delta(13)C-values of both T metabolites (maximum Deltadelta(13)C-values = 5.5 per thousand), as well as by very stable longitudinal T/E profiles and carbon isotopic ratios in the first hours following administration. According to T/E ratios and delta(13)C-values, the washout period after 80 mg TU intake was less than 48 h for all subjects and no accumulation phenomenon was observed upon chronic oral administration.     

Application of high-precision isotope ratio monitoring mass spectrometry to identify the biosynthetic origins of proteins

Isotope ratio monitoring (IRM) mass spectrometry was used to measure the relative abundance of stable isotopes in several samples of adult human hemoglobin expressed in E. coli, yeast, and human blood. The results showed significant differences in the distribution of (15)N and (13)C isotopes among hemoglobin samples produced in these organisms. This indicates that IRM mass spectrometry can be used in forensic protein chemistry to identify the origin of protein expression.     

Floral volatiles fromClarkia breweri andC. concinna (Onagraceae): Recent evolution of floral scent and moth pollination

Clarkia breweri (Onagraceae) is the only species known in its genus to produce strong floral fragrance and to be pollinated by moths. We used gas chromatography-mass spectrometry (GC-MS) to identify 12 abundant compounds in the floral headspace from two inbred lines ofC. breweri. These volatiles are derived from two biochemical pathways, one producing acyclic monoterpenes and their oxides, the other leading from phenylalanine to benzoate and its derivatives. Linalool and linalool oxide (pyran form) were the most abundant monoterpenoids, while linalool oxide (furan form) was present at lower concentrations. Of the aromatic compounds detected, benzyl acetate was most abundant, whereas benzyl benzoate, eugenol, methyl salicylate, and vanillin were present as minor constituents in all floral samples. The two inbredC. breweri lines differed for the presence of the additional benzenoid compounds isoeugenol, methyleugenol, methylisoeugenol, and veratraldehyde. We also analyzed floral headspace fromC. concinna, the likely progenitor ofC. breweri, whose flowers are odorless to the human nose. Ten volatiles (mostly terpenoids) were detected at low concentrations, but only when headspace was collected from 20 or more flowers at a time. Trans--ocimene was the most abundant floral compound identified from this species. Our data are consistent with the hypothesized recent evolution of floral scent production and moth pollination inC. breweri.