A three-enzyme-system to degrade curcumin to natural vanillin

The symmetrical structure of curcumin includes two 4-hydroxy-3-methoxyphenyl substructures. Laccase catalyzed formation of a phenol radical, radical migration and oxygen insertion at the benzylic positions can result in the formation of vanillin. As vanillin itself is a preferred phenolic substrate of laccases, the formation of vanillin oligomers and polymers is inevitable, once vanillin becomes liberated. To decelerate the oligomerization, one of the phenolic hydroxyl groups was protected via acetylation. Monoacetyl curcumin with an approximate molar yield of 49% was the major acetylation product, when a lipase from Candida antarctica (CAL) was used. In the second step, monoacetyl curcumin was incubated with purified laccases of various basidiomycete fungi in a biphasic system (diethyl ether/aqueous buffer). A laccase from Funalia trogii (LccFtr) resulted in a high conversion (46% molar yield of curcumin monoacetate) to vanillin acetate. The non-protected vanillin moiety reacted to a mixture of higher molecular products. In the third step, the protecting group was removed from vanillin acetate using a feruloyl esterase from Pleurotus eryngii (PeFaeA) (68% molar yield). Alignment of the amino acid sequences indicated that high potential laccases performed better in this mediator and cofactor-free reaction

A comparison of cell wall disruption techniques for the isolation of intracellular metabolites from Pleurotus and Lepista sp.

Different techniques were compared for their effectiveness in the disruption of the rigid cell walls of Basidiomycetes, Grinding under liquid nitrogen, stirred glass bead milling and enzymatic cell lysis were applied to the mycelia of Pleurotus sapidus and Lepista irina grown submerged. Each of the disruption procedures was evaluated by testing the quantity and quality of released intracellular metabolites: DNA, RNA, enzymes, and secondary metabolites. The most suitable method for nucleic acid isolation was grinding under liquid nitrogen, while bead mill homogenization was the superior technique for isolation of active enzymes. A new effective method is proposed for isolation of secondary metabolites with the aid of bead milling of fungal mycelia. © 2006 Verlag der Zeitschrift für Naturforschung

Regio- and stereoselective fungal oxyfunctionalisation of limonenes

Selective transformations of limonene by asco- and basidiomycetes were investigated. On the shake flask scale, Penicillium citrinum hydrated R-(+)-limonene to α-terpineol [83% regioselectivity (rs), more than 80 mg l-1 product yield], and Gongronella butleri catalysed the terminal oxidation to yield perillyl alcohol (60% rs, 16 mg l-1). On the laboratory bioreactor scale, Penicillium digitatum produced a peak concentration of 506 mg α-terpineol l-1 in the fed-batch mode, equivalent to a theoretical yield of 67%, and no volatile by-products were found. Fusarium proliferatum transformed R-(+)-limonene enantiospecifically to cis-(+)-carveol (98.6% ee, more than 35 mg l-1 product yield) and S-(-)-limonene predominantly to trans-(-)-carveol (96.3% ee). Pleurotus sapidus selectively dehydrogenised the accumulating trans-(-)-carveol to the corresponding enantiopure R-(-)-carvone. The results show that a careful selection of strain and bioprocess parameters may improve both the yield and the optical purity of a desired product

GC/MS Analysis of Some Bioactive Constituents from Carthamus lanatus L.

Sterols, triterpenes, volatiles, polar and other constituents in aerial parts of Carthamus lanatus were analyzed by gas chromatography-mass spectrometry. Over 90 compounds were identified most of them new for the species. Sitosterol and stigmasterol were the most abundant of 10 sterols identified in the sterol fraction. Taraxasterol, α- and β-amyrine prevailed in the triterpene fraction. Volatiles, sterols and a fraction of the dichloromethane extract showed strong cytotoxicity (Artemia salina assay)

Highly variable pharmacokinetics of tyramine in humans and polymorphisms in OCT1, CYP2D6, and MAO-A

Tyramine, formed by the decarboxylation of tyrosine, is a natural constituent of numerous food products. As an indirect sympathomimetic, it can have potentially dangerous hypertensive effects. In vitro data indicated that the pharmacokinetics of tyramine possibly depend on the organic cation transporter OCT1 genotype and on the CYP2D6 genotype. Since tyramine is a prototypic substrate of monoamine oxidase A (MAO-A), genetic polymorphisms in MAO-A may also be relevant. The aims of this study were to identify to what extent the interindividual variation in pharmacokinetics and pharmacodynamics of tyramine is determined by genetic polymorphisms in OCT1, CYP2D6, and MAO-A. Beyond that, we wanted to evaluate tyramine as probe drug for the in vivo activity of MAO-A and OCT1. Therefore, the pharmacokinetics, pharmacodynamics, and pharmacogenetics of tyramine were studied in 88 healthy volunteers after oral administration of a 400 mg dose. We observed a strong interindividual variation in systemic tyramine exposure, with a mean AUC of 3.74 min*µg/ml and a high mean CL/F ratio of 107 l/min. On average, as much as 76.8% of the dose was recovered in urine in form of the MAO-catalysed metabolite 4-hydroxyphenylacetic acid (4-HPAA), confirming that oxidative deamination by MAO-A is the quantitatively most relevant metabolic pathway. Systemic exposure of 4-HPAA varied only up to 3-fold, indicating no strong heritable variation in peripheral MAO-A activity. Systolic blood pressure increased by more than 10 mmHg in 71% of the volunteers and correlated strongly with systemic tyramine concentration. In less than 10% of participants, individually variable blood pressure peaks by >40 mmHg above baseline were observed at tyramine concentrations of >60 µg/l. Unexpectedly, the functionally relevant polymorphisms in OCT1 and CYP2D6, including the CYP2D6 poor and ultra-rapid metaboliser genotypes, did not significantly affect tyramine pharmacokinetics or pharmacodynamics. Also, the MOA-A genotypes, which had been associated in several earlier studies with neuropsychiatric phenotypes, had no significant effects on tyramine pharmacokinetics or its metabolism to 4-HPAA. Thus, variation in tyramine pharmacokinetics and pharmacodynamics is not explained by obvious genomic variation, and human tyramine metabolism did not indicate the existence of ultra-low or -high MAO-A activity

Revisionen des Porträts. Jenseits von Mimesis und Repräsentation

Noch immer wird das Phänomen ›Porträt‹ im kunsthistorischen Diskurs zumeist unter Begrifflichkeiten wie Identität, Individualität, Repräsentation oder Ähnlichkeit diskutiert. Zeitgenössische amimetische, konzeptuelle und performative Porträtformen werden mit solchen Konzepten jedoch nicht mehr vollständig eingeholt. Der Band befragt deshalb einerseits kritisch diese traditionellen, mimetischen Begriffe anhand von Fallstudien. Andererseits werden ihnen dynamische und offene Konzepte (teils aus Nachbardisziplinen) wie Spur, Berührung, Fraktalität, Defazialisierung oder Dividualität an die Seite gestellt, um den kunsthistorischen Porträt-Begriff in einem fachübergreifenden Diskurs aufzufächern, der auch die Digitalisierung umfasst. ›Porträt‹ wird somit explizit als Konstruktion, self-fashioning und konzeptuelle Praxis des Performativen betrachtet

Grund und Grenzen grundrechtlicher Schutzansprüche | Die subjektiv-rechtliche Rekonstruktion der grundrechtlichen Schutzpflichten und ihre Auswirkung auf die verfassungsrechtliche Fundierung des Verbrauchervertragsrechts

Die grundrechtlichen Schutzpflichten haben sich ein Vierteljahrhundert nach ihrer "Entdeckung" durch das BVerfG (in der ersten Abtreibungsentscheidung) einen festen Platz in der Grundrechtsdogmatik erobert. Die vorliegende Arbeit bietet einen Überblick über den Entwicklungsstand dieser Lehre. Sie widmet sich insbesondere dem Ausgreifen dieser Grundrechtsfunktion in das Zivilrecht.Der Verfasser stellt die bisherige Herleitung der Schutzpflichten vom "Kopf" der Staatszwecklehre auf die "Füße" der Grundrechtsdogmatik. Er ordnet - im Gegensatz zur herrschenden Ansicht - die Schutzpflichten nicht den objektiven, sondern den subjektiven Grundrechtsfunktionen zu. Kern seines subjektiv-grundrechtlichen Begründungsansatzes ist ein zweidimensionaler Freiheitsbegriff; Abwehr- und Schutzpflichtendimension teilen sich das Schutzgut der "Freiheit". Objektive grundrechtliche Schutzpflichten des Staates decken sich hiernach mit den grundrechtlichen Schutzansprüchen des Individuums.Günter Krings zieht auf dieser Begründungsbasis dem Tatbestand und der Rechtsfolge der Schutzpflichten klare Grenzen. Er schließt den Schutz vor Naturgewalten und vor körperimmanenten Gesundheitsstörungen ebenso aus wie den Schutz vor eigenverantwortlicher Selbstschädigung. Der eigenverantwortlich und autonom handelnde Verbraucher kann sich im Verbrauchervertragsrecht i.d.R. nicht auf grundrechtliche Schutzpflichten berufen. Verfassungsrechtliche Impulse für den Verbraucherschutz gehen kaum von den Grundrechten, wohl aber vom Sozialstaatsprinzip aus