Shelf-stable cranberry juice precipitate has not been well characterized. Here, we describe using 1H–13C heteronuclear single quantum coherence–nuclear magnetic resonance (HSQC–NMR) spectroscopy for ...cranberry juice analysis, focusing on proanthocyanidins and the precipitate. HSQC–NMR cross-peaks from juices were categorized as aliphatic, olefinic, aromatic, carbohydrate backbone, or anomeric signals. An average cranberry juice precipitate had significantly more aromatic and significantly less carbohydrate backbone signals than an average supernatant. The precipitate was a collection of biomolecules held together by a mix of weak and strong intermolecular forces. Proanthocyanidin signals from precipitates of juices showed 22 ± 2 to 29.9 ± 0.7% A-type interflavan linkages and 34 ± 2 to 48 ± 3% of flavan-3-ol units with trans stereochemistry between the C2 and C3 positions. Based on this work, 1H–13C HSQC–NMR is useful to analyze cranberry juice and reveals the complex chemical nature of components in the soluble and insoluble phases.
Shelf-stable cranberry juice precipitate has not been well characterized. Here, we describe using
H-
C heteronuclear single quantum coherence-nuclear magnetic resonance (HSQC-NMR) spectroscopy for ...cranberry juice analysis, focusing on proanthocyanidins and the precipitate. HSQC-NMR cross-peaks from juices were categorized as aliphatic, olefinic, aromatic, carbohydrate backbone, or anomeric signals. An average cranberry juice precipitate had significantly more aromatic and significantly less carbohydrate backbone signals than an average supernatant. The precipitate was a collection of biomolecules held together by a mix of weak and strong intermolecular forces. Proanthocyanidin signals from precipitates of juices showed 22 ± 2 to 29.9 ± 0.7% A-type interflavan linkages and 34 ± 2 to 48 ± 3% of flavan-3-ol units with trans stereochemistry between the C2 and C3 positions. Based on this work,
H-
C HSQC-NMR is useful to analyze cranberry juice and reveals the complex chemical nature of components in the soluble and insoluble phases.
Isoprene photochemistry over the Amazon rainforest Liu, Yingjun; Brito, Joel; Dorris, Matthew R. ...
Proceedings of the National Academy of Sciences - PNAS,
05/2016, Letnik:
113, Številka:
22
Journal Article
Recenzirano
Odprti dostop
Isoprene photooxidation is a major driver of atmospheric chemistry over forested regions. Isoprene reacts with hydroxyl radicals (OH) and molecular oxygen to produce isoprene peroxy radicals ...(ISOPOO). These radicals can react with hydroperoxyl radicals (HO₂) to dominantly produce hydroxyhydroperoxides (ISOPOOH). They can also react with nitric oxide (NO) to largely produce methyl vinyl ketone (MVK) and methacrolein (MACR). Unimolecular isomerization and bimolecular reactions with organic peroxy radicals are also possible. There is uncertainty about the relative importance of each of these pathways in the atmosphere and possible changes because of anthropogenic pollution. Herein, measurements of ISOPOOH and MVK + MACR concentrations are reported over the central region of the Amazon basin during the wet season. The research site, downwind of an urban region, intercepted both background and polluted air masses during the GoAmazon2014/5 Experiment. Under background conditions, the confidence interval for the ratio of the ISOPOOH concentration to that of MVK + MACR spanned 0.4–0.6. This result implies a ratio of the reaction rate of ISOPOO with HO₂ to that with NO of approximately unity. A value of unity is significantly smaller than simulated at present by global chemical transport models for this important, nominally low-NO, forested region of Earth. Under polluted conditions, when the concentrations of reactive nitrogen compounds were high (>1 ppb), ISOPOOH concentrations dropped below the instrumental detection limit (<60 ppt). This abrupt shift in isoprene photooxidation, sparked by human activities, speaks to ongoing and possible future changes in the photochemistry active over the Amazon rainforest.
Consumption of flavonoids has been associated with protection against cardiovascular and neurodegenerative diseases. Most dietary flavonoids are subjected to bacterial transformations in the gut ...where they are converted into biologically active metabolites that are more bioavailable and have distinct effects relative to the parent compounds. While some of the pathways involved in the breakdown of flavonoids are emerging, little it is known about the impact of carbon source availability and community dynamics on flavonoid metabolism. This is relevant in the gut where there is a fierce competition for nutrients. In this study, we show that metabolism of one of the most commonly consumed flavonoids, quercetin, by the gut-associated bacterium
is dependent on interspecies cross-feeding interactions when starch is the only energy source available.
can degrade quercetin in the presence of glucose but is unable to use starch for growth or quercetin degradation. However, the starch-metabolizing bacterium
, which does not metabolize quercetin, stimulates degradation of quercetin and butyrate production by
via cross-feeding of glucose and maltose molecules released from starch. These results suggest that dietary substrates and interactions between species modulate the degradation of flavonoids and production of butyrate, thus shaping their bioavailability and bioactivity, and likely impacting their health-promoting effects in humans.
While visual representations are generally thought to help students learn chemistry, they can pose conceptual challenges. Arrows are a common visual feature used prominently across various visuals, ...such as energy diagrams. Although energy diagrams are widely used, research on what challenges arise in the context of energy diagrams is limited. To address this gap, the authors conducted interviews with 121 undergraduate students after they received instruction on atomic orbital energy diagrams. The interviews included two questions that served to get a broad sense of students’ understanding of AOEDs and two questions that specifically focused on students’ understanding of arrows that denote electrons. Students exhibited challenges in understanding electron motion by falsely assuming that electrons consistently follow a patterned motion. Further, students faced challenges understanding the energy of electron spin states and attractive and repulsive forces. These findings illustrate the need to investigate challenges that arise from implied meaning of various visual features of energy diagrams, which is key to developing instruction that helps students overcome challenges that arise in the context of energy diagrams.
Anthocyanins degrade in fruit juice during storage, reducing juice color quality and depleting the health-promoting components of juice. Common water-soluble products of anthocyanins' chemical ...degradation are known, but little is known about the contribution of the insoluble phase to loss processes. Cranberry juice and isolated anthocyanins were incubated at 50 °C for up to 10 days to determine polyphenol profiles and degradation rates. Anthocyanin-proanthocyanidin heteropolymers were analyzed via Matrix Assisted Laser Desorption/Ionization (MALDI)- Time of Flight (TOF) Mass Spectrometry (MS). Formation of soluble protocatechuic acid accounted for 260 ± 10% and insoluble materials for 80 ± 20% of lost soluble cyanidin-glycosides in juice, over-representations plausibly due to quercetin and (epi)catechin in cranberry juice and not observed in the values of 70 ± 20% and 16 ± 6% in the purified anthocyanin system. Loss processes of soluble peonidin-glycosides were better accounted for, where 31 ± 2% were attributable to soluble vanillic acid formation and 3 ± 1% to insoluble materials in cranberry juice and 35 ± 5% to vanillic acid formation and 1.6 ± 0.8% to insoluble materials in the purified anthocyanin system. Free anthocyanins were below quantifiable levels in precipitate, implying most anthocyanins in precipitate were polymeric colors (PCs). PCs in the precipitate included cyanidin- and peonidin-hexosides and -pentosides covalently bonded to procyanidins. Therefore, formation of cranberry juice precipitate does not deplete a large portion of soluble anthocyanins; rather, the precipitate's pigmentation results from PCs that are also present in the soluble phase.
Browning index (BI, ABS520 nm/ABS420 nm) is a measure of anthocyanin‐rich fruit juice pigmentation quality. This study sought to determine the extent to which BI describes anthocyanin quality and ...degradation in fruit juices. Commercial fruit juices were assayed for monomeric anthocyanin (MA) content, percent polymeric color (%PC), pH, and BI. BI varied, 0.29 to 1.72, among cranberry, cherry, grape, aronia, and pomegranate juices. Principal component analysis (PCA) revealed that BI was strongly inversely associated with %PC, and positively correlated with MAs to a lesser extent. The BI of grape and cherry juices varied linearly with pH from 2.0 to 4.0 in pH‐adjusted juices. Cherry and grape juices at pH approximately 2.0 to 4.0 were incubated at 50 °C to induce juice browning. BI and MA decreased, and %PC increased, but the amount of MA degradation was not explained by %PC. In the aged juices, BI and MA were strongly correlated using PCA. In aged grape juice, chromatographic analysis was used characterize anthocyanins, proanthocyanidins, and anthocyanin scission products. Anthocyanin loss and a gain of unresolved components absorbing at 420 nm decreased BI. Proanthocyanidins and co‐eluting pigments with varying BI decreased during aging. Scission products did not account for anthocyanin loss. Thus, MA loss more so than the gain in pigments associated with juice proanthocyanidins contribute to the increase in %PC and decline of the BI during accelerated aging of grape juice. Thus, BI is a useful marker of fruit juice quality within juices of the same pH and anthocyanin composition.
Practical Application
Fruit juice pigmentation depends on anthocyanins, pH, and other matrix components. Spectrophotometric methods to determine pigmentation include the browning index (ABS520 nm/ABS420 nm), pH differential method for monomeric anthocyanin (MA) content, and bisulfite bleaching to determine percent polymeric color (%PC). In this study, anthocyanin‐rich fruit juice browning index was strongly dependent on pH and MA content. MA loss, and to a lesser extent, a gain in newly‐formed pigments at 420 nm contributed to the browning index change during aging. Therefore, browning index is strongly associated with MA content and is useful for assessing fruit juice quality.
Anthocyanins and proanthocyanidins are important both to the health properties of fruits and juice and also to the color quality of juice. Unfortunately, the chemical complexity of juice can make it ...difficult to study these analytes, and their chemical change processes in juices are not well understood. We started with an interrogation of a common metric of polyphenol-rich juice color quality, the browning index (BI), using colorimetry and High-Performance Liquid Chromatography (HPLC) to investigate how BI varied with pH, how it changed with accelerated aging, and how its numerical value and changes in value correlated with pigmented polyphenol composition. Surprisingly, BI had a simple linear response to changes in pH; depended very strongly anthocyanin content; and seemed to have little dependence on polymeric colors, even after extensive accelerated aging. Monitoring polyphenol composition alongside color quality during accelerated aging called attention to an understudied aspect of juice: the intensely pigmented precipitate that formed during accelerated aging and exists in many juices available at market. Our later work focused on understanding the precipitate of juice with special emphasis on the polyphenol composition of the precipitate. We tracked how much of the soluble anthocyanins in cranberry juice were lost to precipitate formation using extraction, acid digestion, and quantification using HPLC, determining that 3–16% of reduction in anthocyanin concentration was attributable to precipitate formation. Further, extraction showed that free anthocyanins could not explain the pigmentation in juice precipitate, and Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) showed that precipitate had an appreciable amount of anthocyanin-proanthocyanidin polymeric colors which could explain the precipitate’s color. Finally, using 1H-13C Heteronuclear Single Quantum Coherence Nuclear Magnetic Resonance (HSQC-NMR) spectroscopy in a new way allowed us to analyze the precipitate of cranberry juice both globally and for some of the specific attributes of proanthocyanidins in the precipitate. The precipitate of cranberry juice appears to be a mixture of lipids, possibly phospholipids; carbohydrates; polyphenols; and possibly protein. Additionally, the new HSQC-NMR technique shows promise for globally analyzing cranberry juice and related samples and statistically distinguishing samples across accelerated aging and based on manufacturer.
In the past few years, there has been an explosion of eye movement research in cognitive science and neuroscience. This has been due to the availability of ‘off the shelf’ eye trackers, along with ...software to allow the easy acquisition and analysis of eye movement data. Accompanying this has been a realisation that eye movement data can be informative about many different aspects of perceptual and cognitive processing. Eye movements have been used to examine the visual and cognitive processes underpinning a much broader range of human activities, including, language production, dialogue, human computer interaction, driving behaviour, sporting performance, and emotional states. Finally, in the past thirty years, there have been real advances in our understanding of the neural processes that underpin eye movement behaviour. The Oxford Handbook of Eye Movements provides a comprehensive review of the entire field of eye movement research. In over fifty articles, it reviews the developments that have so far taken place, the areas actively being researched, and looks at how the field is likely to develop in the coming years. The first section considers historical and background material, before moving onto a second section on the neural basis of eye movements. The third and fourth sections look at visual cognition and eye movements and eye movement pathology and development. The final sections consider eye movements and reading and language processing and eye movements.
Diffuse midline gliomas (DMG) are highly invasive brain tumors with rare survival beyond two years past diagnosis and limited understanding of the mechanism behind tumor invasion. Previous reports ...demonstrate upregulation of the protein ID1 with H3K27M and ACVR1 mutations in DMG, but this has not been confirmed in human tumors or therapeutically targeted.
Whole exome, RNA, and ChIP-sequencing was performed on the ID1 locus in DMG tissue. Scratch-assay migration and transwell invasion assays of cultured cells were performed following shRNA-mediated ID1-knockdown. In vitro and in vivo genetic and pharmacologic cannabidiol (CBD) inhibition of ID1 on DMG tumor growth was assessed. Patient-reported CBD dosing information was collected.
Increased ID1 expression in human DMG and in utero electroporation (IUE) murine tumors is associated with H3K27M mutation and brainstem location. ChIP-sequencing indicates ID1 regulatory regions are epigenetically active in human H3K27M-DMG tumors and prenatal pontine cells. Higher ID1-expressing astrocyte-like DMG cells share a transcriptional program with oligo/astrocyte-precursor cells (OAPCs) from the developing human brain and demonstrate upregulation of the migration regulatory protein SPARCL1. Genetic and pharmacologic (CBD) suppression of ID1 decreases tumor cell invasion/migration and tumor growth in H3.3/H3.1K27M PPK-IUE and human DIPGXIIIP* in vivo models of pHGG. The effect of CBD on cell proliferation appears to be non-ID1 mediated. Finally, we collected patient-reported CBD treatment data, finding that a clinical trial to standardize dosing may be beneficial.
H3K27M-mediated re-activation of ID1 in DMG results in a SPARCL1+ migratory transcriptional program that is therapeutically targetable with CBD.
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