Single and multiple dose pharmacokinetics of maritime pine bark extract (Pycnogenol) after oral administration to healthy volunteers

Background

Since plant extracts are increasingly used as phytotherapeutics or dietary supplements information on bioavailability, bioefficacy and safety are warranted. We elucidated the plasma kinetics of genuine extract components and metabolites after single and multiple ingestion of the standardized maritime pine bark extract Pycnogenol (USP quality) by human volunteers.

Methods

Eleven volunteers received a single dose of 300 mg pine bark extract, five volunteers ingested 200 mg daily for five days to reach steady state concentrations. Plasma samples were obtained before and at defined time points after intake of the extract. Samples were analyzed by HPLC with ion-pair reagents and simultaneous UV and electrochemical detection.

Results

We quantified total plasma concentrations of catechin, caffeic acid, ferulic acid, taxifolin and the metabolite M1 (δ-(3,4-dihydroxy-phenyl)-γ-valerolactone). Additionally, we describe plasma time courses and steady state appearance of ten so far unknown compounds, U1 to U10. After single ingestion, compounds derived from the extract were rapidly absorbed and the majority of them were detectable over whole experimental period of 14 h. The analysis of steady state plasma samples revealed significant phase II metabolism.

Conclusion

We present the first systematic pharmacokinetic analysis of compounds derived from maritime pine bark extract. Beyond the known constituents and metabolites we uncovered the plasma time courses of ten unknown compounds. In concert with our previous detection of anti-inflammatory bioefficacy of these plasma samples ex vivo we suggest that constituents and metabolites of Pycnogenol bear potential for disclosure of novel active principles.     

Supernetwork identifies multiple events of plastid trnF(GAA) pseudogene evolution in the Brassicaceae

The occurrence of nonfunctional trnF pseudogenes has been rarely described in flowering plants. However, we describe the first large-scale supernetwork for the Brassiccaeae built from gene trees for 5 loci (adh, chs, matK, trnL-F, and ITS) and report multiple independent origins for trnF pseudogenes in crucifers. The duplicated regions of the original trnF gene are comprised of its anticodon domain and several other highly structured motifs not related to the original gene. Length variation of the trnL-F intergenic spacer region in different taxa ranges from 219 to 900 bp as a result of differences in pseudocopy number (1-14). It is speculated that functional constraints favor 2-3 or 5-6 copies, as found in Arabidopsis and Boechera. The phylogenetic distribution of microstructural changes for the trnL-F region supports ancient patterns of divergence in crucifer evolution for some but not all gene loci.     

Das Orientierungssystem der V?gel II. Heimfinden und Navigation

Zusammenfassung Die Analyse des Navigationssystems der Vögel bezieht sich meist auf Versuche mit Brieftauben. Kramers Karte-Kompaß-Prinzip geht davon aus, daß die Heimrichtung zunächst als Kompaßkurs bestimmt wird. Dies wurde durch zahlreiche Zeitumstimmungsversuche bestätigt. Damit erscheinen nur zwei Navigationsstrategien möglich: (1) Benutzen von Weginformation, die auf einem Richtungsreferenzsystem beruht, und (2) Benutzen von Ortsinformation, deren Richtungsbeziehung zum Ziel bekannt ist.Junge Tauben, denen während der Verfrachtung der Zugang zu magnetischer Information verwehrt worden war, flogen ungerichtet ab. Dies spricht für eine Navigationsstrategie, bei der die Richtung des Hinwegs mit dem Magnetkompaß gemessen wird. Diese Art von Wegintegration stellt aber nur eine erste Strategie sehr junger, unerfahrener Tauben dar; sobald wie möglich benutzen die Tauben Ortsinformation, denn diese erlaubt Nachbestimmung des Heimkurses und damit das Korrigieren von Fehlern.Navigation anhand von Ortsinformation bedeutet, daß Vögel den Heimkurs aufgrund von Faktoren am Auflaßort bestimmen. Die modernen Vorstellungen berücksichtigen die zentrale Rolle eines äußeren Referenzsystems und gehen von einer Navigationskarte aus, die einer kompaßmäßig ausgerichteten mentalen Repräsentation des Verlaufs der Navigationsfaktoren entspricht. Der Heimkurs wird aus den Unterschieden zwischen den Werten am Auflaßort und denen am Heimatort abgeleitet. Da es sich bei den Navigationsfaktoren um Gradienten handelt, können die Vögel deren Verlauf extrapolieren und ihren Heimkurs auch in unbekanntem Gelände bestimmen. Unregelmäßigkeiten im Gradientenverlauf führen zu Abweichungen von der Heimrichtung, sogenannten Ortsmißweisungen. In der Nähe des Heimatorts wird die Navigationskarte durch eine entsprechende Mosaik-Karte von Landmarken ergänzt.Beide Karten werden durch Lernvorgänge erstellt. Junge Tauben verschaffen sich die notwendige Information auf spontanen Flügen, indem sie Information über den zurückgelegten Weg mit Ortsinformation verknüpfen und gemeinsam in den Karten abspeichern. Bei Tauben wird die Navigationskarte etwa im dritten Lebensmonat funktionstüchtig, aber sie wird auch später noch ständig erweitert und verbessert. Ihre Größe hängt von der Erfahrung der Vögel ab. Die Karte enthält offenbar Entfernungsangaben und erlaubt freie Flüge zwischen beliebigen Zielen. In einigen Punkten entspricht sie der in der psychologischen Literatur diskutierten kognitiven Karte.Das Navigationssystem der Vögel ist dadurch gekennzeichnet, daß sie sich mit Hilfe eines einfachen angeborenen Mechanismus, des Magnetkompaß, viele andere Faktoren durch Lernvorgänge nutzbar machen und diese in komplexe Mechanismen wie die Karten integrieren.

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The orientation system of birds — II. Homing and navigation

Summary The analysis of the navigational system of birds is largely based on experiments with displaced homing pigeons. Kramer's map-and-compass model assumes that the home direction is first established as a compass course. This is confirmed by numerous clock-shift experiments. Consequently, only two types of navigational strategy appear possible: (1) the use of route-specific information based on an external reference or (2) the use of site-specific information whose directional relationship is familiar to the birds.The use of route-specific information is indicated by the finding that young birds deprived of magnetic information during displacement were disoriented, whereas birds receiving the same treatment at the release site were not. This suggests that birds navigate by recording the direction of the outward journey with their magnetic compass, determining the home course by reversing it. This strategy of path integration with the help of an external reference, however, is used only by very young, inexperienced pigeons during an early phase in the development of the navigational system. As soon as birds become more experienced and are able to use site-specific information, they give up route-specific information in favor of the former. The reasons for this change in strategy lie in the fact that using site-specific information enables birds to redetermine their home course as often as necessary, thus allowing the correction of initial mistakes.Site-specific information means that birds can derive their home course from factors perceived at the release site. The present models on navigation acknowledge the crucial role of an external reference system by proposing the navigational map to be a directionally oriented mental representation of the spatial distribution of at least two navigational factors, which are assumed to be environmental gradients. The birds determine their home course by comparing the local values of these factors with the remembered home values. Gradients can be extrapolated beyond the range of direct experience, which explains the birds' ability to home from distant, unfamiliar sites. Deviations from the true home direction, so-called release site biases, as frequently observed in pigeons and other bird species, may be attributed to unforeseen irregularities in the distribution of the navigational factors, which cause birds to misinterpret their position. Near home, the navigational or grid map is supplemented by the mosaic map, which is supposed to be a directionally oriented mental representation of the distribution of familiar landmarks.Both maps are based on experience. Young birds obtain the relevant information during spontaneous flights by combining information on the route travelled with information on the location of prominent landmarks and the direction of environmental gradients. In pigeons, the maps become functional during the third month of life. They are continuously enlarged and updated also in later years. The total size of the navigational map appears to depend on the spatial range of the birds' experience. The maps seem to include information on distance; they are not restricted to homing, but allow free movements between arbitrary goals. In several respects, the model of the avian navigational map is similar to the concept of the cognitive map discussed in psychological literature, the main differences being the larger distances involved, the representation of continuous environmental gradients instead of separate entities, and the essential role of an external reference.The navigational system of birds is thus characterized as utilizing a wide variety of environmental cues. Learning processes, which are based on a simple, innate mechanism, the magnetic compass, integrate these cues and form complex, experience-based mechanisms, such as the maps.

     

CD4+ T cell-associated pathophysiology critically depends on CD18 gene dose effects in a murine model of psoriasis

In a CD18 hypomorphic polygenic PL/J mouse model, the severe reduction of CD18 (beta(2) integrin) to 2-16% of wild-type levels leads to the development of a psoriasiform skin disease. In this study, we analyzed the influence of reduced CD18 gene expression on T cell function, and its contribution to the pathogenesis of this disease. Both CD4(+) and CD8(+) T cells were significantly increased in the skin of affected CD18 hypomorphic mice. But only depletion of CD4(+) T cells, and not the removal of CD8(+) T cells, resulted in a complete clearance of the psoriasiform dermatitis. This indicates a central role of CD4(+) T cells in the pathogenesis of this disorder, further supported by the detection of several Th1-like cytokines released predominantly by CD4(+) T cells. In contrast to the CD18 hypomorphic mice, CD18 null mutants of the same strain did not develop the psoriasiform dermatitis. This is in part due to a lack of T cell emigration from dermal blood vessels, as experimental allergic contact dermatitis could be induced in CD18 hypomorphic and wild-type mice, but not in CD18 null mutants. Hence, 2-16% of CD18 gene expression is obviously sufficient for T cell emigration driving the inflammatory phenotype in CD18 hypomorphic mice. Our data suggest that the pathogenic involvement of CD4(+) T cells depends on a gene dose effect with a reduced expression of the CD18 protein in PL/J mice. This murine inflammatory skin model may also have relevance for human polygenic inflammatory diseases.     

Excessive iron accumulation in the pea mutants dgl and brz: subcellular localization of iron and ferritin

The pea (Pisum sativum L.) mutants dgl and brz are defective in the regulation of iron uptake. Enhanced proton extrusion and constitutively high Fe(III) reductase activities in the roots lead to an accumulation of iron and other divalent cations in different organs of the mutants. Ultrastructural investigations of the basal leaflets of the mutants revealed in the cytoplasm, in mitochondria and especially in, or close to the endoplasmic reticulum numerous electron-dense particles which were absent in the corresponding wild type plants DGV and Sparkle. By means of electron-spectroscopic imaging and electron-energy-loss spectroscopy it could be shown that these electron-dense particles consist mainly of iron. Some of the iron deposits were immunocytochemically identified as the iron-storage protein ferritin. It is suggested that the precipitation of excessive iron in the dgl and brz mutant leaves in the form of electron-dense iron particles combined with the accumulation of ferritin is part of the plant defense mechanism against Fe-mediated oxidative stress. Received: 17 February 1998 / Accepted: 4 July 1998     

Temporal fluctuations of the geomagnetic field affect pigeons’ entire homing flight

Tracks of pigeons, recorded with the help of GPS-receivers from two sites 30 km north and south of the Frankfurt loft, were analyzed in view of an influence of irregular fluctuations of the geomagnetic field. The data obtained were correlated with indices characterizing different aspects of these fluctuations. We found the best correlations with the index quantifying the average amplitude of the magnetic disturbance, and with an index that quantifies the average variability of the magnetic field on the day of release: stronger and more variable fluctuations lead to a counter-clockwise shift of the mean headings during the initial phase at the release site and the following departure phase, but not during the final homing phase leading to the loft. The steadiness of flight was not affected during the initial phase; however, during the later parts of the homing flight, stronger fluctuations, as well as higher variability in the magnetic field led to a marked decrease in steadiness. This continuing effect of magnetic fluctuations indicates that magnetic factors not only affect the beginning, but remain an integral part of the pigeons’ navigational processes during the entire homing flight.     

Orientation of birds in total darkness

Magnetic compass orientation of migratory birds is known to be light dependent, and radical-pair processes have been identified as the underlying mechanism. Here we report for the first time results of tests with European robins, Erithacus rubecula, in total darkness and, as a control, under 565 nm green light. Under green light, the robins oriented in their normal migratory direction, with southerly headings in autumn and northerly headings in spring. By contrast, in darkness they significantly preferred westerly directions in spring as well as autumn. This failure to show the normal seasonal change characterizes the orientation in total darkness as a "fixed direction" response. Tests in magnetic fields with the vertical or the horizontal component inverted showed that the preferred direction depended on the magnetic field but did not involve the avian inclination compass. A high-frequency field of 1.315 MHz did not affect the behavior, whereas local anesthesia of the upper beak resulted in disorientation. The behavior in darkness is thus fundamentally different from normal compass orientation and relies on another source of magnetic information: It does not involve the radical-pair mechanism but rather originates in the iron-containing receptors in the upper beak.     

Magnetic intensity affects cryptochrome-dependent responses in Arabidopsis thaliana

Cryptochromes are blue-light absorbing photoreceptors found in many organisms where they have been involved in numerous growth, developmental, and circadian responses. In Arabidopsis thaliana, two cryptochromes, CRY1 and CRY2, mediate several blue-light-dependent responses including hypocotyl growth inhibition. Our study shows that an increase in the intensity of the ambient magnetic field from 33–44 to 500 μT enhanced growth inhibition in A. thaliana under blue light, when cryptochromes are the mediating photoreceptor, but not under red light when the mediating receptors are phytochromes, or in total darkness. Hypocotyl growth of Arabidopsis mutants lacking cryptochromes was unaffected by the increase in magnetic intensity. Additional cryptochrome-dependent responses, such as blue-light-dependent anthocyanin accumulation and blue-light-dependent degradation of CRY2 protein, were also enhanced at the higher magnetic intensity. These findings show that higher plants are sensitive to the magnetic field in responses that are linked to cryptochrome-dependent signaling pathways. Because cryptochromes form radical pairs after photoexcitation, our results can best be explained by the radical-pair model. Recent evidence indicates that the magnetic compass of birds involves a radical pair mechanism, and cryptochrome is a likely candidate for the avian magnetoreception molecule. Our findings thus suggest intriguing parallels in magnetoreception of animals and plants that appear to be based on common physical properties of photoexcited cryptochromes.