Isolierung, Charakterisierung und Synthese von Aromavorläufern aus Wein, Dillkraut und Lindenblüten

Den Schlüsselaromastoffen von Dillkraut (Dillether), einiger Weißweinvarietäten (Weinlacton) und Lindenblüten (Lindenether) liegt die gleiche chemische Grundstruktur eines Benzofuranrings zugrunde. Weiterhin gemeinsam sind ihnen die geringe Geruchsschwelle und der angenehme Aromaeindruck. Ziel dieser Arbeit stellte die Aufklärung ihrer Aromavorläufer dar. Der erste Teil der Arbeit beschreibt die präparative Isolierung eines Monoterpensäure-glukoseesters mittels chromatographischer Techniken (SFE, SC, MLCCC und HPLC) unter laufender Kontrolle der Fraktionierung mittels GC-MS. Die Strukturaufklärung gelang mittels DCI-MS und moderner ein- und multidimensionaler NMR-techniken. Nach der Synthese der Referenzverbindung wurde diese in Modellwein gelagert. Über einen säurekatalysierten Ringschluß konnte aus der Vorstufe Weinlacton gebildet werden. In Gärungsversuchen mit verschiedenen Hefestämmen konnte dagegen keine Bildung von Weinlacton aus der Vorstufe beobachtet werden. Im zweiten Teil der Arbeit wurden aus frischen Dillspitzen polare Aromapräkursoren isoliert. Hier gelang es eine großen Menge (100 mg/6 Kg Dill) eines bisher unbekannten Glukosids zu isolieren und dessen Struktur mittels HR-MS und multidimensionaler NMR-techniken aufzuklären. Eine chemische Zuckerabspaltung und Reduktion führte unter spontanem Ringschluß zur Bildung von Dillether. Aus getrockneten bzw. frischen Lindenblüten wurden im letzten Teil der Arbeit 24 Aromavorläufer isoliert. Blank et al. konnten 1990 zeigen, daß der Lindenether als natürliches Racemat vorliegt und postulierten folglich eine chemisch Bildung aus einer diolischen Monoterpenverbindung. Diese konnte in dieser Arbeit nicht nachgewiesen werden.The aroma character impact compounds of dill (dill ether), of some specific white wine varieties (wine lactone) and also lime blossoms (linden ether) share the same chemical benzofuran skeleton. Further common sensory criteria, like the very low odour threshold, and the attractive flavor sensation, arise the question about the responsible precursors. The first part of the work describes the preparative isolation of a monoterpenic glucose ester by chromatographic techniques (SPE, SC, MLCCC, and HPLC) under continuos monitoring of the fractions by GC-MS. Structure elucidation was achieved by DCI-MS and modern one and two dimensional NMR techniques. Authentic reference material was further synthesized and stored in model wine solution. Wine lactone was generated by acid catalyzed cyclization, whereas fermentation experiments with different yeast strains was not successful to yield wine lactone from the isolated and synthesized compound. In the second part of the work polar aroma precursors were isolated from fresh dill herb. A high amount of a new glucoside was isolated and characterised by HR-MS and multidimensional NMR techniques. After chemical cleavage of the sugar moiety and reduction (NaBH4) spontaneous cyclization took place at elevated temperature to form the dill ether

Acute and Chronic Effects of Green Oat (Avena sativa) Extract on Cognitive Function and Mood during a Laboratory Stressor in Healthy Adults: A Randomised, Double-Blind, Placebo-Controlled Study in Healthy Humans

Green oat (Avena sativa) extracts contain several groups of potentially psychoactive phytochemicals. Previous research has demonstrated improvements in cognitive function following a single dose of these extracts, but not following chronic supplementation. Additionally, whilst green oat extracts contain phytochemicals that may improve mood or protect against stress, for instance species-specific triterpene saponins, to date this possibility has not been examined. The current study investigated the effects of a single dose and four weeks of administration of a novel, Avena sativa herbal extract (cognitaven®) on cognitive function and mood, and changes in psychological state during a laboratory stressor. The study adopted a dose-ranging, double-blind, randomised, parallel groups design in which 132 healthy males and females (35 to 65 years) received either 430 mg, 860 mg, 1290 mg green oat extract or placebo for 29 days. Assessments of cognitive function, mood and changes in psychological state during a laboratory stressor (Observed Multitasking Stressor) were undertaken pre-dose and at 2 h and 4 h post-dose on the first (Day 1) and last days (Day 29) of supplementation. The results showed that both a single dose of 1290 mg and, to a greater extent, supplementation for four weeks with both 430 mg and 1290 mg green oat extract resulted in significantly improved performance on a computerised version of the Corsi Blocks working memory task and a multitasking task (verbal serial subtractions and computerised tracking) in comparison to placebo. After four weeks, the highest dose also decreased the physiological response to the stressor in terms of electrodermal activity. There were no treatment-related effects on mood. These results confirm the acute cognitive effects of Avena sativa extracts and are the first to demonstrate that chronic supplementation can benefit cognitive function and modulate the physiological response to a stressor

Feeding a grape seed extract extends the survival of the red flour beetle Tribolium castaneum under heat-stress depending on nrf-2, jnk-1, and foxo-1 homologous genes but independent of catechin monomers

Besides caloric restriction, a diet rich in fruits and vegetables is believed to delay the ageing process thus providing a powerfull tool in preventive medicine. To investigate underlying interactions between food ingredients and genes simple models, such as the red flour beetle Tribolium castaneum, appear especially constructive. Here we show that 1 % of a grape seed extract containing 30 % of procyanidins, significantly increases the survival of T. castaneum at 42 °C when added to flour as a dietary source. The beneficial effects of grape seed extract could not be reproduced by supplementing flour with single catechins of which the oligomeric procyanidins consist. We identified previously stress resistance genes responsible for a survival extension by dietary ingredients and show here by the use of RNA-interference that a knockdown of transcripts encoding homologues of Nrf-2 or Jnk-1 block the effects of grape seed extract on survival. Interestingly, grape seed extract under knockdown of Foxo-1 caused a significant survival reduction, stressing the hormetic response as underlying the survival extension by the dietary interventions. In conclusion, our studies provide evidence that a procyanidin-rich extract is able to extend the survival of the model organism T. castaneum. Catechin monomers, however, appear not to mediate the effects. The active ingredients, moreover, need the presence of stress resistance factors, and here especially of Foxo-1, in order to promote their preventive activities with regard to degenerations

Bioavailability Study of Maqui Berry Extract in Healthy Subjects

Several health promoting effects have been reported for maqui berry, rich in anthocyanins. Direct effects of anthocyanins as well as bioactive metabolites might be involved. Within the study, bioavailability of a proprietary standardized maqui berry extract Delphinol® was investigated based on two selected anthocyanins (delphinidin-3-O-glucoside (DS) + cyanidin-3-O-sambubioside (CS)) and two breakdown products (protocatechuic acid (PCA) + gallic acid (GA)) after a single-dose supplementation in humans. Pharmacokinetic parameters were calculated from individual concentration time curves. In all 12 subjects a significant increase was noted in plasma values of DG and CS after intake of maqui berry extract. Maximum concentration of DG was observed after 1.0 ± 0.3 h and CS after 2.0 ± 1.1 h. Within 8 h, concentrations nearly returned to baseline levels. The results confirm a fast uptake and metabolism of the two selected key substances. Additionally, the phenolic acids GA and PCA were observed as breakdown products of anthocyanins. In summary, the study clearly confirms the bioavailability of maqui berry extract and its specific anthocyanin compounds and related breakdown products in healthy subjects