Flavonoids alter P-gp expression in intestinal epithelial cells in vitro and in vivo

Flavonoids are secondary plant metabolites included in our diet but are also provided in a growing number of supplements. They are suggested to interact with intestinal transport systems including phospho-glycoprotein (P-gp) which mediates the efflux of a variety of xenobiotics back into the gut lumen. In human intestinal Caco-2 cells, we tested the effects of 14 different flavonoids on P-gp expression in vitro. Protein expression levels were quantified by Western blotting, flow cytometry, and real-time PCR. Except apigenin, all flavonoids at concentrations of 10 microM increased P-gp expression in Western blotting experiments when cells were exposed to the compounds over 4 wk. Flavone was one of the most effective P-gp inducers in Caco-2 cells and its effects were, therefore, also assessed for changes in P-gp in vivo in the gastrointestinal tract of C57BL/6 mice. P-gp expression was significantly increased by flavone (400 mg/kg body weight x day over 4 wk) in the small intestine but not in the colon which displayed intrinsically the highest expression level. In conclusion, the increase in P-gp expression caused by flavonoids in intestinal epithelial cells in vitro and also in vivo may serve as an adaptation and defense mechanism limiting the entry of lipophilic xenobiotics into the organism.     

Catalytic reduction of NOx over transition-metal-containing MCM-41

The catalytic properties of Pt, Rh and Co supported on mesoporous molecular sieves with MCM-41-type structure consisting of SiO₂ and Al₂O₃ were studied for the reduction of NO with propene. Pt supported on siliceous MCM-41 was the most active catalyst, however, significant quantities of undesirable N₂O were formed during the reaction. Pt supported on mesoporous Al₂O₃ and Rh supported on both mesoporous oxides showed a lower activity, but an improved selectivity towards N₂ formation. Co supported on MCM-41-type materials had only a low level of activity for the reduction of NO with propene. For Pt supported on MCM-41-type materials only a minor decrease in the activity was observed when water vapor was added into the reactant gas mixture, while on Rh- and Co-containing catalysts the activity strongly decreased. This revised version was published online in July 2006 with corrections to the Cover Date.     

Oxokohlenstoffe und verwandte Verbindungen. 20. Durch Arylmercaptane induzierte Überführung von Semiquadratsäurehydraziden in Quadratsäure-1,2-diamide

Oxocarbons and Related Compounds. 20. By Thiophenols Mediated Conversion of Semisquaric Hydrazides to Squaric-1,2-Diamides In the presence of thiophenols semisquaric hydrazides ( 4 ) are converted into squaric-1,2-diamides ( 6 ) upon heating in alcoholic solution. Proof is given that thiosquaric-S-ester-amides ( 8 ) are intermediates in this process.     

Über die Synthese von Pyrimidindionen-(2,4) aus Ketonen und Harnstoff

The Synthesis of Pyrimidine-2,4-diones from Ketones and Urea By reaction of urea with 2-alkylcyclohexanones or with 2-alkylcyclohexanonecarboxamides 8-alkyl-5,6,7,8-tetrahydrobenzo-[1,2-d]pyrimidine(1H,3H)-2,4-diones ( 5a–i ) are formed. Cyclohexanone or cyclohexanone-2-carboxamide with urea form 5,6,7,8-tetrahydro-benzo-[1,2-d]pyrimidine(1H,3H)-2,4-dione ( 3 ). Menthone, 2,6-dimethylcyclohexanone, 3,5-diphenylcyclohexanone, cyclooctanone and cyclododecanone with urea yield pyrimidinediones 9, 10, 11, 12a and 12b .     

Über die Synthese von α-Pyridonen aus Ketonen und Harnstoff

The Synthesis of α-Pyridones from Ketones and Urea By acid-catalyzed reaction of ketones with urea, the condensed α-pyridones 2, 8, 9, 10, 12a–d are formed.     

Sugar profile and physicochemical properties of Ethiopian monofloral honey

Three hundred twenty honey samples were collected from Ethiopia, and categorized into nine monofloral honeys using melissopalynology. Theses monofloral honeys were investigated for their sugar profile, physicochemical properties, and quality of honeys. Sugars (fructose, glucose, sucrose, maltose, turanose, and isomaltose) were identified using high-performance liquid chromatography and physicochemical properties (moisture, water activity, pH, acidity, ash, minerals, conductivity, colour) using the Harmonized Method of the International Honey Commission. Moisture and water activity showed a strong regression coefficient (r² = 0.92). Moisture content alone did not sufficiently describe the quality of honey during storage and processing.     

Ultrafast X-ray absorption studies of the structural dynamics of molecular and biological systems in solution

We review our recent studies of excited state structures and dynamics of chemical and biological systems with pico- and femtosecond X-ray absorption spectroscopy in the liquid phase.