Optimization of SPME-Arrow-GC/MS Method for Determination of Free and Bound Volatile Organic Compounds from Grape Skins.

(1) Background: Solid phase microextraction (SPME)-Arrow is a new extraction technology recently employed in the analysis of volatiles in food materials. Grape volatile organic compounds (VOC) have a crucial role in the winemaking industry due to their sensory characteristics of wine.; (2) Methods: Box-Behnken experimental design and response surface methodology were used to optimise SPME-Arrow conditions (extraction temperature, incubation time, exposure time, desorption time). Analyzed VOCs were free VOCs directly from grape skins and bound VOCs released from grape skins by acid hydrolysis.; (3) Results: The most significant factors were extraction temperature and exposure time for both free and bound VOCs. For both factors, an increase in their values positively affected the extraction efficiency for almost all classes of VOCs. For free VOCs, the optimum extraction conditions are: extraction temperature 60 °C, incubation time 20 min, exposure time 49 min, and desorption time 7 min, while for the bound VOCs are: extraction temperature 60 °C, incubation time 20 min, exposure time 60 min, desorption time 7 min.; (4) Conclusions: Application of the optimized method provides a powerful tool in the analysis of major classes of volatile organic compounds from grape skins, which can be applied to a large number of samples.

Chemical characterization, antiproliferative and antifungal activities of Clinacanthus nutans.

Clinacanthus nutans Lindau (Family: Acanthaceae) is a medicinal herb widely distributed in the tropic and subtropic areas of Asia. C. nutans is traditionally consumed as vegetable or herbal tea, as well as a folk medicine for anticancer and antifungal activities. However, to date, chemical constituent responsible for observed health beneficial effects of this medicinal plant is not clear. In the current study, 32 compounds (1-32), including three new megastigmanes (1-3) were isolated from the aerial parts of C. nutans. Their structures were elucidated on the basis of comprehensive NMR, MS, and CD spectroscopic data analysis, as well as chemical hydrolysis. Among the isolates, cycloartane triterpenoids (9, 10, and 12) displayed moderate anti-proliferative effects against HepG2 cell growth with IC50 values ranging from 9.12 to 19.89 µM. Data obtained from flow cytometry analysis and western blotting assays revealed that compounds 9 and 12 induced apoptosis of HepG2 cells by modulating the expression of proteins associated to mitochondrial-mediated apoptotic pathway. Furthermore, megastigmanes 1, 2, 7, and 8 enhanced the anti-Candida albicans activity of amphotericin B (AmB), supporting the synergistic effects between megastigmanes and AmB. This is the first report of anticancer and antifungal potential of cycloartane triterpenoids and megastigmanes in C. nutans, which shed useful insights on the relationship between C. nutans's chemical constituent and its beneficial effects to health. Findings from this study support further development of this medicinal plant for potential pharmaceutical applications.

Insights into the major aroma-active compounds in clear red raspberry juice (Rubus idaeus L. cv. Heritage) by molecular sensory science approaches.

The major aroma-active compounds in clear red raspberry juice were identified by molecular sensory science approaches. Thirty-one aroma-active compounds were identified using detection frequency analysis and aroma extract dilution analysis. Among them, 18 volatiles with aroma activity in red raspberry were identified for the first time, while 14 volatiles with odor activity values (OAVs) ≥ 1 were confirmed as the major aroma-active compounds. Three C6 aldehydes showed the highest detection frequencies of 8, and ß-ionone exhibited the highest OAV of 9507 and flavor dilution factor of 512, which indicated that the floral and grassy note could be dominant in overall aroma. Quantitative descriptive analysis suggested that the grassy, floral, woody, and caramel-like notes can be simulated using aroma recombination model 1. Electronic nose analysis also demonstrated that model 1 had closer similarity to the original juice than others. The combination strategy used here would help improve the knowledge of red raspberry aroma.

Megastigmane Derivatives from the Cladodes of Opuntia humifusa and Their Nitric Oxide Inhibitory Activities in Macrophages.

Opuntia humifusa, known as the eastern prickly pear cactus and locally called "Cheonnyuncho" in Korea, is cultivated widely on Jeju Island, Korea. Phytochemical analysis of the methanolic extract of the cladodes of O. humifusa, for which previous research is relatively limited, was performed under the guidance of LC/MS-based analysis. As a result, one new megastigmane (1) and four new megastigmane glucosides (2-5) were isolated along with 18 known compounds (6-23). The structures of the new compounds were established by 1D and 2D NMR and HRESIMS, and their absolute configurations were established by chemical reactions, quantum chemical electronic circular dichroism calculations, and DP4+ analysis using the gauge-including atomic orbital NMR chemical shift calculations as well as the application of Snatzke's method. The isolated compounds (1-23) were tested for NO production inhibition in lipopolysaccharide (LPS)-induced RAW 264.7 cells to investigate their anti-inflammatory effects. Compounds 10 and 11 exhibited significant inhibitory effects on LPS-induced NO production in a dose-dependent manner. The potential mechanistic pathway of 10 and 11 was also investigated using Western blotting, indicating that compounds 10 and 11 inhibit NO through iNOS expression.

Revealing the Usefulness of Aroma Networks to Explain Wine Aroma Properties: A Case Study of Portuguese Wines.

Wine aroma is the result of complex interactions between volatile compounds and non-volatile ones and individual perception phenomenon. In this work, an aroma network approach, that links volatile composition (chromatographic data) with its corresponding aroma descriptors was used to explain the wine aroma properties. This concept was applied to six monovarietal wines from Bairrada Appellation (Portugal) and used as a case study. A comprehensive determination of the wines' volatile composition was done (71 variables, i.e., volatile components), establishing a workflow that combines extraction techniques and gas chromatographic analysis. Then, a bipartite network-based approach consisting of two different nodes was built, one with 19 aroma descriptors, and the other with the corresponding volatile compound(s). To construct the aroma networks, the odor active values were calculated for each determined compound and combined with the bipartite network. Finally, the aroma network of each wine was compared with sensory descriptive analysis. The analysis of the specific aroma network of each wine revealed that Sauvignon Blanc and Arinto white wines present higher fruity (esters) and sweet notes (esters and C13 norisoprenoids) than Bical wine. Sauvignon Blanc also exhibits higher toasted aromas (thiols) while Arinto and Bical wines exhibit higher flowery (C13 norisoprenoids) and herbaceous notes (thiols), respectively. For red wines, sweet fruit aromas are the most abundant, especially for Touriga Nacional. Castelão and Touriga Nacional wines also present toasted aromas (thiols). Baga and Castelão wines also exhibit fusel/alcohol notes (alcohols). The proposed approach establishes a chemical aroma fingerprint (aroma ID) for each type of wine, which may be further used to estimate wine aroma characteristics by projection of the volatile composition on the aroma network.

Ebenamariosides A-D: Triterpene Glucosides and Megastigmanes from the Leaves of Diospyros maritima.

The 1-BuOH-soluble fraction of the methanol (MeOH) extract of Diospyros maritima was separated by chromatographic techniques to give three new oleanane-type and one new ursane-type triterpene glucoside, named ebenamariosides A-D (1-4); two megastigmanes were also isolated. The structures of triterpene glucosides was elucidated with extensive investigation by one and two dimensional NMR spectroscopy and the structures were confirmed by partial enzymatic hydrolyses to give the corresponding mono-glucosides and aglycones. The structures of the megastigmanes, including their absolute stereochemistries, were elucidated by spectroscopic evidence and by the modified Mosher's method. Two megastigmanes were chemically correlated and their absolute structures were unambiguously determined. The cytotoxicity of the triterpene glucosides and their degradation products were assayed. They did not show any significant activity.

Characterization of the Key Aroma Compounds in Marselan Wine by Gas Chromatography-Olfactometry, Quantitative Measurements, Aroma Recombination, and Omission Tests.

Key odorants of red wine made from the hybrid grapes of Marselan (Vitis vinifera L.) were isolated by solid-phase extraction (SPE) and explored by gas chromatography-olfactometry (GC-O) analysis. Application of aroma extract dilution analysis (AEDA) revealed 43 odor-active compounds, and 31 odorants among them were detected with flavor dilution (FD) factors ranging from 9 to 2187. Comprehensive two-dimensional gas chromatography and time-of-flight mass spectrometry (GC × GC-TOF-MS) were exploited to quantitate the aroma-active compounds with FD ≥9. The identification indicated ß-damascenone as having the highest FD factors, followed by eugenol, 2,3-butanedione, citronellol, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, phenethyl acetate, guaiacol, and 2-methoxy-4-vinylphenol. A total of 21 compounds were found to have odor activity values (OAVs) >1.0. Aroma reconstitution validation experiments showed a good similarity of blackberry, green pepper, honey, raspberry, caramel, smoky, and cinnamon aroma attributes between the original Marselan wine and the reconstructed wine. In addition, omission tests were carried out to further determine the contribution of odorants to the overall aroma.

Labdanes and megastigmanes from Vitex negundo var. heterophylla.

The aromatic plants of Vitex negundo var. heterophylla are not only herb medicine but also a functional food and an industrial crop. Its leaves can be used as a functional food for improving human's health, but the previous studies mainly focused on the volatile constituents, lignans, and iridoids. Our research led to the isolation of four new terpenoids (1-4), together with fifteen known compounds including seven flavonoids (9-15), two jasmonates (7-8) and six terpenoids (5-6, 16-19) from the leaves. Among all these compounds, 1, 2, 11, and 19 exhibited strong inhibitory activity against NO production in lipopolysaccharide (LPS)-induced RAW264.7 macrophage. The anti-inflammatory mechanism of the most active compound (2) is related to the inhibition of iNOS and COX-2, and the suppression of NF-κB pathway. Therefore, terpenoids and flavonoids from the leaves of Vitex negundo var. heterophylla might be used as potential anti-inflammatory candidates for developing medicine or value-added functional food.

Recovery of Natural α-Ionone from Fermentation Broth.

Recently, the market value of aromas has constantly been rising. Because the supply from natural feedstock is limited, the biotechnological production has received more interest. Thus far, only a few attempts have been made to produce α-ionone, a valued essential aroma of raspberry, biotechnologically. This study reports a production process for enantiopure (R)-α-ionone from lab scale (2-150 L) with typical titer of 285 mg/L broth to industrial scale (up to 10 000 L) with a titer up to 400 mg/L broth, focusing on the development of a downstream process with a maximized yield at minimized effort. The developed recovery consists of solid-liquid extraction from the biomass at φ = 0.4 g of n-hexane/g of biomass for 90 min at ambient temperature and adsorption from the aqueous supernatant at Φ = 0.5 g of Diaion HP-20/mg of α-ionone, followed by desorption at Ψ = 30 g of n-hexane/g of Diaion HP-20. Altogether, natural α-ionone could be gained in substantial quantity and purity of >95%.

Triterpenoids, megastigmanes and hydroxycinnamic acid derivatives from Anisomeles indica.

Six triterpenoids (1-6), four megastigmanes (7-10) and five hydroxycinnamic acid derivatives (11-15) were isolated from the aerial part of Anisomeles indica (Lamiaceae). Of these components, compound 1 was identified to be a new triterpenoid with the structure of 2α,3α,19α-trihydroxyurs-12,20(30)-dien-28-oic acid based on extensive analysis of MS, 1D and 2D NMR spectroscopic data, while compounds 2-13 were obtained for the first time from Anisomeles species.

A new norisoprenoid from the leaves of Ficus pumila.

One new norisoprenoid 3,9-dihydroxy dihydro actinidiolide (1), together with eleven known compounds (2-12), were isolated from ethanol extract of the leaves of Ficus pumila collected in Hainan Province, China. Their structures were elucidated by the detailed analysis of comprehensive spectroscopic data. Compounds 1, 2, 4, 5, 8 and 10-12 were isolated from the F. pumila for the first time. All compounds were evaluated for their cytotoxic activity. Compounds 3 and 9 showed weak cytotoxic activity against Hela, MCF-7 and A549 cell lines.

Unravelling wine volatile evolution during Shiraz grape ripening by untargeted HS-SPME-GC × GC-TOFMS.

The influence of grape maturity on wine volatome was investigated using HS-SPME-GC × GC-TOFMS. Shiraz wines were made from grapes harvested from four different vineyards from two berry maturity levels. A total of 1276 putative compounds were detected in at least one of the wine samples and 175 showed significant trends related to grape maturity. The first two dimensions of the Principal component analysis accounted for 57% of the variation and separated the samples according to the harvest date. Wines from the first harvest date were characterised by an abundance of lipoxygenase derived compounds, norisoprenoids and sulfur-containing compounds whereas a significant increase in some acetate esters was observed in wines produced from the more mature grapes. This study demonstrated a common evolution of grape volatiles for Shiraz inside the same mesoclimate. During the late ripening stage of the grape, a direct nexus between sugar concentration and wine volatile evolution was not observed.

HPTLC Autography Based Screening and Isolation of Mushroom Tyrosinase Inhibitors of European Plant Species.

In the course of this project, 133 plants were evaluated on their ability to inhibit tyrosinase, a key enzyme in melanogenesis. The screening was performed by means of a HPTLC autographic assay, resulting in the selection of three plants, Asplenium trichomanes, Pinus uncinata, and Scutellaria altissima, with promising tyrosinase inhibiting activities. With the aid of the HPTLC assay, it was not only possible to select the most interesting plant extracts, but also to monitor the activity-guided fractionation which, in a relatively short time period, led to the isolation of active principles. Benzoic acid, roseoside, and dihydrovomifoliol-O-ß-d-glucopyranoside could be identified as tyrosinase inhibitors present in P. uncinata. Globularin turned out to be the active principle of S. altissima, and 4-ethenylphenyl 6-O-(6-deoxy-α-l-mannopyranosyl)-ß-d-glucopyranoside was detected as tyrosinase inhibitor of A. trichomanes. The pure compounds were tested also in a 96 well-plate assay in order to determine their IC50 values. The lowest IC50 value (42 µm) could be obtained for globularin, whereas the other compounds, e. g., benzoic acid exhibited a rather high IC50 value (IC50 =552 µm). This stood in clear contrast to the autographic assay, but is has to be taken into account that the outcome of the autography assay is not only depending on the IC50 value of a compound, but also on the content of the respective constituent in the extract.

(2R,5S)-Theaspirane Identified as the Kairomone for the Banana Weevil, Cosmopolites sordidus, from Attractive Senesced Leaves of the Host Banana, Musa spp.

The principal active component produced by highly attractive senesced host banana leaves, Musa spp., for the banana weevil, Cosmopolites sordidus, is shown by coupled gas chromatography-electroantennography (GC-EAG), coupled GC-mass spectrometry (GC-MS), chemical synthesis and coupled enantioselective (chiral) GC-EAG to be (2R,5S)-theaspirane. In laboratory behaviour tests, the synthetic compound is as attractive as natural host leaf material and presents a new opportunity for pest control.

Megastigmane glycosides from Urena lobata.

Five new megastigmane glycosides, urenalobasides A-E (1-5), together with 11 known ones (6-16) were isolated from Urena lobata. Their structures were determined by extensive spectroscopic and spectrometric data (1D and 2D NMR, IR, and HRESIMS) and calculated electronic circular dichroism method. Compounds 1 and 2 are two unusual megastigmanes structurally containing a 6/5 fused ring system. Compound 3 exhibits inhibition of nitric oxide production in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells with IC50 value of 53.7 ±â€¯1.0 µM (positive control, dexamethasone, IC50 = 16.6 ±â€¯0.8 µM).

Effect of Vertical Shoot-Positioned, Scott-Henry, Geneva Double-Curtain, Arch-Cane, and Parral Training Systems on the Volatile Composition of Albariño Wines.

Viticultural practices influence both grape and wine quality. The influence of training systems on volatile composition was investigated for Albariño wine from Rías Baixas AOC in Northwest Spain. The odoriferous contribution of the compounds to the wine aroma was also studied. Volatile compounds belonging to ten groups (alcohols, C6-compounds, ethyl esters, acetates, terpenols, C13-norisoprenoids, volatile phenols, volatile fatty acids, lactones and carbonyl compounds) were determined in Albariño wines from different training systems, Vertical Shoot-Positioned (VSP), Scott-Henry (SH), Geneva Double-Curtain (GDC), Arch-Cane (AC), and Parral (P) during 2010 and 2011 vintages. Wines from GDC showed the highest total volatile composition with the highest concentrations of alcohols, ethyl esters, fatty acids, and lactones families. However, the highest levels of terpenes and C13-norisoprenoids were quantified in the SH system. A fruitier aroma was observed in Albariño wines from GDC when odor activity values were calculated.

Phytochemical study of Juglans regia L. leaves.

A methanolic extract of Juglans regia L. leaves was fractioned by various chromatographic techniques yielding a total of 40 metabolites belonging to megastigmane, tetralone, phenylpropanoid, neolignane and juglone glycosides. Ten unknown megastigmane glucoside derivatives (juglanionosides A-K, 1-10) and six unknown tetralone glucoside derivatives (juglanosides J-O, 11-16) together with 24 known compounds - among them 16 described for the first time in Juglans - were isolated. As characteristic structural feature, the previously undescribed compounds showed acylation of the sugar units with sinapic, ferulic, coumaric, benzoic or salicylic acid. Their chemical structures were elucidated on the basis of 1D and 2D NMR techniques, HRESIMS as well as CD spectroscopy. Absolute stereochemistry was revealed by mild alkaline hydrolysis and comparison of CD and polarimetric data to literature values.

Aliphatic Glucoside, Zanthoionic Acid and Megastigmane Glucosides: Zanthoionosides A-E from the Leaves of Zanthoxylum ailanthoides.

From the leaves of Zanthoxylum ailanthoides, 4'-O-p-E-coumaric acid esters of 2-propanol ß-D-glucopyranoside, megastigmane and megastigmane glucosides were isolated. Their structures were elucidated by spectroscopic evidence. The absolute configurations of the megastigmane and aglycone of megastigmane glucosides were determined by the octant rule and modified Mosher's method after protection of carboxylic acids by p-bromophenacyl esters and primary alcohols by pivaloyl esters.

Constituents of Polygala flavescens ssp. flavescens and Their Activity as Inhibitors of Human Lactate Dehydrogenase.

Four new flavonol glycosides (1-4), two oligosaccharides (5, 6), one α-ionone (7), and three triterpenoid saponins (8-10), together with four known secondary metabolites (11-14), were isolated from the aerial parts of Polygala flavescens ssp. flavescens. All structures were elucidated on the basis of their spectroscopic and spectrometric data. The isolates were assayed for their inhibitory activity against isoform 5 of human lactate dehydrogenase, and compound 11 (3,6'-di-O-sinapoylsucrose) showed an IC50 value of 90.4 µM. Modeling studies were carried out to suggest the putative interaction mode of compound 11 in the enzyme active site.

Megastigmane glucosides isolated from Dichrocephala benthamii.

The present study was designed to investigate the chemical constituents of the whole herb of Dichrocephala benthamii. A new megastigmane glucoside (compound 1), together with its four known analogues (compounds 2-5), was obtained. Their structures were elucidated on the basis of spectroscopic analyses (UV, IR, MS, and 1D and 2D NMR). The absolute configuration of compound 1 was assigned on the basis of CD method and chemical evidence. In addition, their cytotoxicity against human hepatoma cells (HepG-2) was evaluated by the MTT method. Compound 5 showed weak activity against HepG-2, while the other compounds did not show remarkable inhibitory effects.