Wein — Qualität entscheidet sich in Nanogramm: Zur Biochemie des sortentypischen Weinaromas

The varietal aroma of most wines is determined by a relatively small number of odor-active compounds, that are generated in ripening berries. These trace compounds occur in the ppb-to ppt-range and are mainly monoterpenes, C₁₃-norisoprenoids, thiols and pyrazines. Identification and elucidation of their biosynthetical pathways are important to unlocking the secrets of wine flavor.     

Tracing phenolic biosynthesis in Vitis vinifera via in situ C-13 labeling and liquid chromatography–diode-array detector–mass spectrometer/mass spectrometer detection

Phenolic compounds in Vitis vinifera contribute important flavor, functionality, and health qualities to both table and wine grapes. The plant phenolic metabolic pathway has been well characterized, however many important questions remain regarding the influence of environmental conditions on pathway regulation. As a diagnostic for this pathway's regulation, we present a technique to incorporate a stable-isotopic tracer, l-phenyl-¹³C₆-alanine (Phe¹³), into grape berries in situ and the accompanying high throughput analytical method based on LC–DAD–MS/MS to quantify and track the label into phenylalanine metabolites. Clusters of V. vinifera cv. Cabernet Sauvignon, either near the onset of ripening or 4 weeks later, were exposed to Phe¹³ in the vineyard. Phe¹³ was present in berries 9 days afterwards as well as labeled flavonols and anthocyanins, all of which possessed a molecular ion shift of 6 amu. However, nearly all the label was found in anthocyanins, indicating tight regulation of phenolic biosynthesis at this stage of maturity. This method provides a framework for examining the regulation of phenolic metabolism at different stages of maturity or under different environmental conditions. Additionally, this technique could serve as a tool to further probe the metabolism/catabolism of grape phenolics.     

Quantification approach for assessment of sparkling wine volatiles from different soils, ripening stages, and varieties by stir bar sorptive extraction with liquid desorption

Stir bar sorptive extraction with liquid desorption followed by large volume injection coupled to gas chromatography-quadrupole mass spectrometry (SBSE-LD/LVI-GC-qMS) was applied for the quantification of varietal and fermentative volatiles in sparkling wines. The analytical data were performed by using suitable standards of monoterpene hydrocarbons (α-pinene), monoterpenols (linalool), sesquiterpenoids (E,E-farnesol, Z-nerolidol, and guaiazulene), C₁₃ norisoprenoids (β-ionone), aliphatic and aromatic alcohols (hexanol and 2-phenylethanol), and esters (hexyl acetate and ethyl decanoate) as model compounds. The wine volatiles were quantified using the structurally related standards. The methodology showed good linearity over the concentration range tested, with correlation coefficients ranging from 0.950 to 0.997, and a reproducibility of 9-18%. The SBSE-LD/LVI-GC-qMS methodology allowed, in a single run, the quantification of 71 wine volatiles that can be quantified accurately at levels lower than their respective olfactory thresholds. This methodology was used for assessment of sparkling wine volatiles from different soils, ripening stages, and varieties. The variety and soil influenced significantly the volatile composition of sparkling wines; lower effect was observed for the ripening stage of grapes picked up one week before or after the maturity state.     

A Non‐Enzymatic Pathway with Superoxide in Intracellular Terpenoid Synthesis

Non‐C₅‐units terpenoids (norisoprenoids) with an acetonyl group are widely distributed in nature. However, studies on the biosynthesis of norisoprenoids are scarce. Now, the C₃₃ norisoprenoid, (all‐E)‐farnesylfarnesylacetone, was identified from Bacillus spp. and it was elucidated for the first time that superoxide mediates the cleavage of menaquinones (vitamin K) to form norisoprenoids in saponification treatment. From in vivo experiments using gene‐disrupted Bacillus subtilis strains targeted for enzymes responsible for menaquinone biosynthesis and for superoxide dismutase, it was suggested that the non‐enzymatic cleavage (autoxidation) of menaquinone with superoxide resulted in norisoprenoid synthesis in Bacillus cells. Furthermore, the bioactive norisoprenoids, farnesylacetone and phytone, were produced in Bacillus cells by this novel synthesis system.     

The Allelopathic Activity of Extracts and Isolated from Spirulina platensis

We determined the allelopathic effects of crude organic (hexane, ethyl acetate, and methanol) extracts of the cyanobacterial Spirulina platensis on barnyardgrass (Echinochloa crus-galli (L.) Beauv.) and Chinese amaranth (Amaranthus tricolor L.). The crude ethyl acetate extract showed the highest inhibitory activity and was subsequently fractionated by column chromatography into 23 fractions based on thin-layer chromatography band pattern similarities. Four concentrations (2000, 1000, 500, and 250 ppm) of each fraction were tested for their allelopathic activity. Fractions E6 and E13 exhibited the most significant inhibitory effects against Chinese amaranth. The constituents of the highly active E6F3-E6F5 fractions determined by GC-MS, chromatography, and spectroscopy included the fatty acids, γ-linolenic acid 15, oleic acid 12, and predominantly palmitic acid 7; minor constituents included 2-ethyl-3-methylmaleimide 9 and C₁₁ norisoprenoids (dihydroactinidiolide 10 and 4-oxo-β-ionone 13). Isolation of E13 fraction by column chromatography revealed four C₁₃ norisoprenoids: 3-hydroxy-β-ionone 17, 3-hydroxy-5α,6α-epoxy-β-ionone 18, 3-hydroxy-5β,6β-epoxy-β-ionone 19, and loliolide 20. Their structures were elucidated by NMR spectroscopy. All six isolated norisoprenoids inhibited seed germination and seedling growth of Chinese amaranth at concentrations of 250–1000 ppm. Allelochemicals from S. platensis could be utilized in the development of novel bioactive herbicides.     

The Chemistry of Rose Pigments

In this article we present a survey of the pigments found in the flowers and fruits of old and modern varieties of roses. The yellow colors are produced by carotenoids, the reds by anthocyanins, and the modern oranges by a mixture of the two. The great structural diversity of the carotenoids contrasts with a surprisingly small number of anthocyanins. For the carotenoids found in roses, a clear correspondence exists between the structure and the breeding partners used; the old yellow roses, which arose from crosses with Chinese varieties, mainly contain carotenoids from early stages in the biosynthesis, while in the modern yellow roses, which are descended from Central Asian foetida types, hydroxylations, epoxidations, and epoxide transformations readily occur. A recently elucidated carotenoid degradation sequence follows the scheme C₄₀ → C₁₃ + C₂₇ → C₁₃ + C₁₄. The C₁₃ compounds are odoriferous substances that contribute to the scent of roses. In the physiological pH region, copigmentation with flavonol glycosides is crucial for stabilization of the anthocyanin chromophores. Many roses, including the “apothecary's rose”, which was once used medicinally, contain large amounts of strongly astringent ellagitannins, monosaccharide esters of gallic acid.     

Quality Characteristics and Anthocyanin Profiles of Different Vitis amurensis Grape Cultivars and Hybrids from Chinese Germplasm

To evaluate the important Vitis amurensis germplasm, the quality characteristics and anthocyanin profiles of the ripe berries of 20 V. amurensis grapes and 11 interspecific hybrids in two consecutive years were analysed. Compared with the V. vinifera grapes, V. amurensis grapes had small berries with low total soluble solids and high titratable acids, and were richer in phenolic compounds except for flanan-3-ols in their skins but had lower phenolic contents in their seeds and showed lower antioxidant activities. An outstanding feature of the V. amurensis grapes was their abundant anthocyanin contents, which was 8.18-fold higher than the three wine grapes of V. vinifera. The anthocyanin composition of V. amurensis was characterized by an extremely high proportion of diglucoside anthocyanins (91.71%) and low acylated anthocyanins (0.04%). Interestingly, a new type of speculated 3,5,7-O-triglucoside anthocyanins was first identified and only detected in V. amurensis grapes and hybrids. Based on the total phenolic and anthocyanin characteristics, V. amurensis grapes were set apart from V. vinifera cultivars and the interspecific hybrids, for the same qualities, fell between them, as assessed by principal component analysis.     

A population analysis of the bonding in N2O4, B2Cl4, B2F4, C2H4 and C3H4

Population matrices have been calculated from molecular orbital wave functions of N₂O₄, B₂Cl₄, and B₂F₄ in order to understand further the bonding in these molecules which are isoelectronic in valence electrons but different in structure. C₂H₄ and C₃H₄ have been included in this study as check cases.

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Zusammenfassung Ausgehend von Molekülorbitalen werden Besetzungsmatrizen für N₂O₄, B₂Cl₄ und B₂F₄ berechnet, um die Bindung in diesen Molekülen, die in den Valenzelektronen isoelektronisch sind, aber unterschiedliche Strukturen aufweisen, besser zu verstehen. C₂H₄ und C₃H₄ sind in dieser Untersuchung als Prüffälle eingeschlossen.

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Résumé Des matrices d'occupation ont été calculées à partir des orbitales moléculaires de N₂O₄, B₂Cl₄ et B₂F₄, afin de comprendre plus profondément la liaison dans ces molécules, qui sont isoélectroniques par leurs électrons de valence, mais qui n'ont pas la même structure. C₂H₄ et C₃H₄ sont considérés dans cette étude à titre de vérification.

     

Investigation of common fluorophores for the detection of nitrated explosives by fluorescence quenching

This study assessed the impact of fruit temperature on the phenolic metabolism of grape berries (Vitis vinifera L. cv. Merlot) grown under field conditions with controlled exposure to sunlight. Individual cluster temperatures were manipulated in situ. Diurnal temperature fluctuation was damped by daytime cooling and nighttime heating of clusters. Daytime-only and nighttime-only temperature controls were applied for comparison. Berry temperatures were recorded continuously to compare the chemical data. Samples collected at véraison indicated that damping the diurnal temperature fluctuation advanced the onset of ripening. Those berries were larger (double-damped: 0.753 ± 0.015 g berry⁻¹ vs control: 0.512 ± 0.034 g berry⁻¹) and more colored than all others. Development of phenolic metabolites was followed by two reversed-phase high performance liquid chromatography methods and gel permeation chromatography. These methods provided information on anthocyanins, proanthocyanidins, flavonols, flavan-3-ol monomers, and polymeric material. Damping the diurnal temperature fluctuation reduced proanthocyanidin mean degree of polymerization (double-damped: 21.8 ± 1.0 vs control: 28.0 ± 1.7). Proanthocyanidin accumulation at véraison was linearly related to heat summation over the developmental period with nighttime heating yielding the highest concentration and daytime cooling yielding the lowest (night-heat: 1.46 ± 0.13 mg berry⁻¹ vs day-cool: 0.97 ± 0.09 mg berry⁻¹). Damping the diurnal temperature fluctuation had a marked effect on the rate of fruit development whereas total heat summation had more of an effect on phenolic metabolism alone. The results provide insight on the direct effect of temperature on phenolic metabolism.     

Compositional Changes in Grapes and Leaves as a Consequence of Smoke Exposure of Vineyards from Multiple Bushfires across a Ripening Season

The negative effects of smoke exposure of grapes in vineyards that are close to harvest are well documented. Volatile phenols in smoke from forest and grass fires can contaminate berries and, upon uptake, are readily converted into a range of glycosylated grape metabolites. These phenolic glycosides and corresponding volatile phenols are extracted into the must and carried through the winemaking process, leading to wines with overtly smoky aromas and flavours. As a result, smoke exposure of grapes can cause significant quality defects in wine, and may render grapes and wine unfit for sale, with substantial negative economic impacts. Until now, however, very little has been known about the impact on grape composition of smoke exposure very early in the season, when grapes are small, hard and green, as occurred with many fires in the 2019–20 Australian grapegrowing season. This research summarises the compositional consequences of cumulative bushfire smoke exposure of grapes and leaves, it establishes detailed profiles of volatile phenols and phenolic glycosides in samples from six commercial Chardonnay and Shiraz blocks throughout berry ripening and examines the observed effects in the context of vineyard location and timing of smoke exposure. In addition, we demonstrate the potential of some phenolic glycosides in leaves to serve as additional biomarkers for smoke exposure of vineyards.     

A new column system for isothermal gas chromatographic analysis of light gases (H2, O2, N2, CO,CH4, CO2, C2H4, C2H6 and C2H2) employing a column switch technique

Summary A new column system for the isothermal analysis of H₂, O₂, N₂, CO, CH₄, CO₂, C₂H₄, C₂H₆ and C₂H₂ is described. Higher hydrocarbons and water are backflushed from the system. The use of 13X molecular sieve in a relatively deactivated state shortens the elution times of the light components and improves peak shapes. Both factors enable quantitative analyses to be carried out satisfactorily at lower concentrations than would otherwise be possible. Analysis of all compounds listed can be carried out in eleven minutes. Sparingly activated 13X molecular sieve columns have proved to be very stable and rarely require reactivation.The method of column switching employed avoids the use of mechanical valves in the sample path and is suitable for automatic operation.

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Neue Trennsäulenkombination für die GC-Analyse von Gasen (H₂, O₂, N₂, CO, CH₄, CO₂, C₂H₄, C₂H₆, C₂H₂) unter Anwendung einer nichtmechanischen Säulenschalttechnik

Zusammenfassung Eine neue Trennsäulenkombination zur isothermen Trennung von H₂, O₂, N₂, CO, CH₄, CO₂, C₂H₄, C₂H₆ und C₂H₂ wird beschrieben. Höhere Kohlenwasserstoffe und Wasser werden rückgespült. Durch Anwendung eines auf relativ niedriger Aktivitätsstufe betriebenen Molekularsiebs 13X wird die Elutionszeit der flüchtigen Komponenten verkürzt und deren Peakform verbessert. Beides erlaubt befriedigende quantitative Analysen im Bereich kleinerer Konzentrationen, als dies mit anderen Systemen möglich ist. Die Analyse eines Gemisches aller oben angeführten Komponenten ist innerhalb von 11 Minuten möglich. Mäßig aktivierte Trennsäulen mit Molekularsieb 13X erwiesen sich als sehr stabil, sie erfordern nur selten eine Reaktivierung. Die hier verwendete Säulenschalttechnik vermeidet die Anwendung mechanischer Umschaltsysteme im Probenweg und ist für eine automatische isotheme Arbeitsweise besonders geeignet.

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Une nouvelle combinaison de colonnes pour l'analyse à température constante, par chromatographie en phase gazeuse, de gaz légers (H₂, O₂, N₂, CO, CH₄, CO₂, C₂H₄, C₂H₆ et C₂H₂) employant un système de commutation de colonnes

Résumé On décrit une nouvelle combinaison de colonnes pour l'analyse à température constante des mélanges de H₂, O₂, N₂, CO, CH₄, CO₂, C₂H₄, C₂H₆ et C₂H₂. Les hydrocarbures à plus grand nombre de carbones et l'eau sont éliminés du système par contrebalayage. L'emploi de tamis moléculaire 13X dans un état de désactivation relativement élevé permet de réduire les temps d'élution des composants légers et de rendre la forme des pics plus favorable. Ces deux facteurs permettent d'effectuer des analyses quantitatives à des concentrations plus basses que celles possibles normalement. L'analyse de tous les composants cités peut être faite en 11 minutes. Les colonnes de Tamis moléculaire 13X à degré d'activation modéré sont très stables et leur réactivation n'est nécessaire qu'après une longue période d'emploi. La méthode de commutation employée pour les colonnes évite l'utilisation de vannes mécaniques sur le parcours de l'échantillon; elle est convenable pour le fonctionnement automatique.

     

In vitro degradation of poly(lactide-co-p-dioxanone)-based shape memory poly(urethane-urea)

The degradation of poly(lactide-co-p-dioxanone)-based shape memory poly(urethane-urea) (SMPU) in vitro was investigated by observing the changes of the pH value of incubation media, weight loss rate, molecular weight and scanning electron microscopy (SEM) during degradation duration of 12 weeks. Moreover, ¹H NMR was used to precisely study the degradation position by calculating the change of characteristic peaks value. The results revealed that the introduction of p-dioxanone (PDO) and -NH-(CO)- and -HN-(CO)-NH- would increase the hydrophilicity of polymer, so the degradation of SMPUs is higher than PDLLA control in the initial time, however, the degradation rate decreased in the anaphase of degradation, which can be attributed to the alkalic -NH₂ from the NH₂ and -NH-(CO), -NH-(CO)-NH-.     

Further prenylated flavonols from Platanus acerifolia’s unripe buds

In addition to the methylated and prenylated flavonoids previously reported from Platanus acerifolia, the multistep chromatographic processing of the toluene extract of defatted fresh unripe buds resulted in the isolation of 8 metabolites. They corresponded to 5,7-dihydroxychromone, strobopinin [(2S)-5,7-dihydroxy-6-C-methylflavanone] as well as to six prenylated flavonols. Divided into two groups of three isomers, these C₅-substituted flavonols are derived from either galangin (5,7-dihydroxyflavonol) or kaempferide (5,7-dihydroxy-4′-methoxyflavonol). Four of them, unknown in the plant kingdom and with either open or cyclized C₅ chain, are discussed for the ¹³C NMR chemical shift variations when going from the open side C₅ chain to the cyclized chain isomers.     

Glycosylated platycosides: Identification by enzymatic hydrolysis and structural determination by LC–MS/MS

In this study, enzymatic hydrolysis and chemometric methods were utilized to discriminate glycosylated platycosides in the extract of Platycodi Radix by LC–MS. Laminarinase, whose enzymatic activity was evaluated using gentiobiose and laminaritriose, was a suitable enzyme to identify the glycosylated platycosides. The laminarinase produced deapi‐platycodin D and platycodin D from the isolated deapi‐platycoside E and platycoside E through the loss of two glucose units by enzymatic reaction, respectively. After hydrolyzing a crude extract by laminarinase, the reconstructed total ion chromatogram generated by a chemometric technique sorted peaks of deglycosylated platycosides easily. Structural information of the glycosylated isomers was revealed through fragment ions generated by the sodiated C_0β ion corresponding to reduced disaccharides in the positive MS⁴ spectra. Characteristic fragment ions of Glc‐(1→6)‐Glc moieties were observed through ring cleavages of ^0,2A_0β, ^0,3A_0β, and ^0,4A_0β, whereas Glc‐(1→3)‐Glc moieties produced only ^0,3A_0β ions. Lithium‐adducted platycosides allowed more detailed structural analysis of glycosidic bond cleavage corresponding to Y_1β and B_1β in addition to ring cleavage.     

Optimization of Fluidized-Bed Extraction for Determination of Organochlorine Pesticides in Sediment

A new extraction technique, fluidized-bed extraction, has been investigated for isolation of organochlorine pesticides from sediment. The extraction was optimized, by means of a surface-response design, by considering the number of extraction cycles, the holding time after reaching the heating temperature, and the composition of the extraction solvent as experimental variables. The effect on method performance of the operating conditions used for fluidized-bed extraction was investigated. Special emphasis was given to accurate determination of p,p′-DDT, because DDT is known to be unstable during GC injection. To evaluate the extent of degradation of DDT, ¹³C₁₂-p,p′-DDT-solutions were analyzed and the amount of degradation during GC injection was calculated. ¹³C₁₂-p,p′-DDT was also added to sediment samples before extraction and the extent of degradation during the optimization experiment was investigated. Finally, classical Soxhlet extraction was compared with the optimized fluidized-bed extraction method.     

Polyphenolic Compounds of Crataegus Berry,Leaf, and Flower Extracts Affect Viability and Invasive Potential of Human Glioblastoma Cells

Crataegus contains numerous health-promoting compounds that are also proposed to have anti-cancer properties. Herein, we aimed at a contemporaneous evaluation of the effects of polyphenol-rich extracts of berries, leaves, and flowers of six Crataegus species on the viability and invasive potential on the highly aggressive human glioblastoma U87MG cell line. The treatment with the extracts evoked cytotoxic effects, with the strongest in the berry extracts. All extracts not only promoted the apoptosis-related cleavage of poly (ADP-ribose) polymerase 1 (PARP1) but also substantially inhibited the activity of pro-survival kinases, focal adhesion kinase (FAK), and protein kinase B (PKB; also known as Akt), thus indicating the suppression of proliferative and invasive potentials of the examined glioblastoma cells. The qualitative and quantitative characterization of the extracts’ content was also performed and revealed that amongst 37 polyphenolic compounds identified in the examined Crataegus extracts, the majority (29) was detected in berries; the leaf and flower extracts, exerting milder cytotoxic effects, contained only 14 and 13 compounds, respectively. The highest polyphenol content was found in the berries of C. laevigata x rhipidophylla x monogyna, in which flavan-3-ols and phenolic acids predominated. Our results demonstrated that a high content of polyphenolic compounds correlated with the extract cytotoxicity, and especially berries were a valuable source of compounds with anti-cancer potential. This might be a promising option for the development of an effective therapeutic strategy against highly malignant glioblastomas in the future.     

General synthesis of sugar-pendant 1,3-propanediamines containing a C-glycoside linkage

A straightforward route to C-glycoside linked sugar-pendant 1,3-propanediamines is described. The three-step preparation procedure involves (1) C-glycosylation of an OH-protected α-glycosyl halide with malononitrile, (2) catalytic hydrogenation of the nitriles to amines, and (3) deprotection of acetyl groups via acid-catalyzed hydrolysis. In the case of the galactose derivative, excess sodiomalononitrile promotes the second addition of a carbanion in the first step. The β-anomeric configuration was confirmed by X-ray crystallography of the glycosylated intermediates. This method demonstrates a general method to access a new class of carbohydrate-pendant C-glycoside chelators.     

Pyrolysis-gas chromatographic analysis of alkylbenzenes

Summary The identification of alkylbenzenes by pyrolysis-gas chromatography was carried out through the analysis of the light pyrolysis products. In the range of C₇ to C₁₂ a number of 43 alkylbenzenes was investigated. All these compounds were unambiguously identified as well as the isomers which do not give significant differences in the mass spectra. A possible degradation mechanism is discussed.

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Pyrolyse-gas-chromatographische Analyse von Alkylbenzolen

Zusammenfassung Die Identifizierung von Alkylbenzolen durch Pyrolyse-Gas-Chromatographie wurde durch die Analyse der leichten Pyrolyseprodukte vorgenommen. Im Bereich von C₇ bis C₁₂ wurden 43 Alkylbenzole untersucht. Alle diese Verbindungen wurden zweifelsfrei identifiziert, ebenso wie auch die Isomeren, die im Massenspektrum keine signifikanten Unterschiede ergeben. Ein möglicher Abbaumechanismus wird diskutiert.

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Analyse d'alkylbenzènes par chromatographie en phase gazeuse de leurs produits de pyrolyse

Résumé L'identification d'alkylbenzènes par chromatographie en phase gazeuse a été effectuée par l'analyse des produits légers de la pyrolyse. Dans le cas des composés en C₇ à C₁₂, 43 alkyl-benzènes ont été étudiés. Tous ces composés ont été identifiés sans ambiguité, ainsi que les isomères auxquels ne correspondent pas de différences significatives des spectres de masse. Un mécanisme possible de dégradation est étudié.

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This work was supported by grants from the Scientific Exchange Agreement SEA     

Fourier transform infrared spectroscopy and solid-state nuclear magnetic resonance studies of octadecyl modified metal oxides obtained from different silane precursors

Octadecyl (C₁₈) modified metal oxide substrates, including titania, zirconia, hafnia, and alumina, are prepared using two types of silylating reagents, n-octadecyltrihydridosilane and n-octadecyltrichlorosilane. Fourier transform infrared (FTIR) and solid-state ²⁹Si nuclear magnetic resonance (NMR) measurements are performed to examine the cross-linking of the silanes. Solid-state ¹³C NMR spectroscopy provides information about the conformation and mobility of surface-immobilized alkyl chains. Variable temperature FTIR investigations are carried out to study the influence of the organosilane precursors and metal oxides on the conformational order of the alkyl modified systems. It is found that grafting by means of n-octadecyltrichlorosilane yields higher grafting densities than surface modification with n-octadecyltrihydridosilane. Combined pyridine adsorption and diffuse reflectance infrared Fourier transform (DRIFT) measurements are performed on the titania and hafnia substrates to evaluate potential surface heterogeneities, i.e. Lewis and Brønsted sites. Differences in the alkyl chain conformational order within the series of C₁₈ modified metal oxides are explained by the presence of island structures. The reduced C₁₈ conformational order for the samples grafted with n-octadecyltrihydridosilane is traced back to the lower grafting density which in turn points to a lower reactivity of this silylating reagent. The most striking result is the higher conformational order of the C₁₈ chains grafted in the present surface modified metal oxides when compared with silica-based systems. This finding is attributed to the lower porosity of the metal oxide supports along with more closely packed chains on the surface.