Decrease in skin permeation and antibacterial effect of parabens by a polymeric additive, poly(2-methacryloyloxyethyl phosphorylcholine-co-butylmetacrylate)

The inhibitory effect of poly(2-methacryloyloxyethyl phosphorylcholine-co-butylmetacrylate) (PMB) on the in vitro skin permeation of p-hydroxybenzoic acid and its esters (parabens; methylparaben, ethylparaben, n-propylparaben and n-butylparaben) as model compounds was evaluated. Solubility of the parabens in distilled water was increased by addition of PMB, and the increasing ratio was dependent on the concentration of PMB. The increment of the ratio was more marked in lipophilic parabens than hydrophilic ones. Skin permeability of parabens from their aqueous suspensions was decreased by addition of PMB, and the decreasing ratio was dependent on the PMB concentration. Then, antibacterial effect of parabens of their aqueous solutions was determined with and without PMB by measuring minimum inhibitory concentration (MIC) against E. coli and S. aureus. As results, MIC and antibacterial effect were increased and decreased, respectively, by addition of PMB. The contribution of PMB was more marked in butylparaben than methylparaben. These decreases in skin permeation and antibacterial effect of parabens by PMB are probably due to a higher solubility in water and a lower partition to the skin and bacterial membranes of parabens by addition of PMB.     

Production of meiosis-activating sterols from metabolically engineered yeast

Meiosis-activating sterols (MAS), a class of potent regulators of reproductive processes, are difficult to obtain by chemical synthesis or isolation from natural sources. We demonstrate the development of metabolically engineered strains of Saccharomyces cerevisiae that accumulate MAS as the predominant sterol product. Homologous recombination was used to construct an erg24Delta erg25Delta hem1Delta mutant RXY4.3, which lacked sterol Delta14 reductase, C-4 oxidase, and delta-aminolevulinate synthase. The HEM1 deletion allowed sterol import and rendered RXY4.3 viable under aerobic conditions. This mutant accumulated 4,4-dimethyl-5alpha-cholesta-8,14,24-trien-3beta-ol (FF-MAS), and a similar erg25Delta hem1Delta mutant produced 4,4-dimethyl-5alpha-cholesta-8,24-dien-3beta-ol (T-MAS). Based on consistent yields of approximately 5 mug of FF-MAS per mL of culture, fermentation of genetically modified yeast compares favorably with other approaches to produce MAS.     

Characterization of Bi5Nb3O15 by refinement of neutron diffraction pattern, acid treatment and reaction of the acid-treated product with n-alkylamines

The structure of Bi₅Nb₃O₁₅ was investigated by refinement of the powder neutron diffraction pattern as well as by structural change through acid treatment and subsequent treatments of an acid-treated product with n-alkylamines. Rietveld refinement suggests that Bi₅Nb₃O₁₅ adopts a mixed-layer Aurivillius-related phase structure, [Bi₂O₂]+[NbO₄]+[Bi₂O₂]+[BiNb₂O₇] [Pnc2 (space group No. 30)] with a=2.1011(4), b=0.5473(1) and c=0.5463(1) nm. After the acid treatment of Bi₅Nb₃O₁₅ with 3 mol/L HCl, a new reflection (at 2.25 nm after drying at room temperature or at 1.89 nm after drying at 120 °C) appeared in the X-ray diffraction (XRD) pattern in addition to the reflections due to Bi₅Nb₃O₁₅. Upon acid treatment, a part of the Bi ions were lost and essentially no Nb ions were dissolved during acid treatment to give a Bi/Nb molar ratio of 1.4. The TG curves of the acid-treated product showed mass loss (ca. 4 mass%) in the range of 300-600 °C. It was also demonstrated that the particle shapes did not change upon acid treatment. The reaction of the acid-treated product (after drying at room temperature) with n-alkylamines led to a shift of the newly appearing reflection to a lower angle, and the d-value of the low-angle reflection increased linearly in accordance with the increment of the number of carbon atoms in n-alkylamines. These results indicate that the [Bi₂O₂] sheet in Bi₅Nb₃O₁₅ was partially leached by acid treatment to form a layered compound H₄BiNb₃O₁₁·xH₂O, capable of accommodating n-alkylamines in the interlayer space, and its anhydrous form, H₄BiNb₃O₁₁, upon drying. Based on the variation in the interlayer distance upon intercalation of n-alkylamines into the acid-treated product, the structure of the acid-treated product can be suggested to comprise alternately stacked protonated [BiNb₂O₇] and [NbO₄] sheets, a result consistent with the Rietveld refinement of Bi₅Nb₃O₁₅.     

Remarkable effect of 2[small alpha]-modification on the VDR antagonistic activity of 1small alpha-hydroxyvitamin D3-26,23-lactones

Novel 2[small alpha]-methyl-, 2[small alpha]-(3-hydroxypropyl)- and 2[small alpha]-(3-hydroxypropoxy)-substituted 25-dehydro-1[small alpha]-hydroxyvitamin D-26,23-lactone derivatives were efficiently synthesized Reformatsky type allylation and palladium-catalyzed alkenylative cyclization processes, and their biological activities were evaluated. Introducing functional groups into the 2[small alpha]-position of the vitamin D-26,23-lactones resulted in remarkable enhancement of their antagonistic activity on vitamin D receptor (VDR).     

Absolute configuration and conformation of 1,1′-spirob[benz[g]indan]

Two diastereomers of 3,3′-di-t-butyl-1,1′-spirobi[benz[g]indan] have been prepared; c.d. spectral evidence is presented for the difference between their conformations.     

Lamellar thickness of polyethylene single crystal isothermally crystallized in dilute solution

Summary Polyethylene single crystals were formed isothermally from 0.1% solution in tetralin (at 77.2, 84.8, and 89.8°C) and n-hexadecane (106.6°C), and those lamellar thicknesses were investigated as a function of crystallization time. These crystals have revealed no change or, if any, a little change in the lamellar thickness. Even for the crystals formed at considerably high temperature, 106.6°C, at which the segmental motion in a cyrstal begins to become active, the increase in those lamellar thicknesses was of the order of 10 Å. When polyethylene fractions with different molecular weight were crystallized at the same temperature, those lamellar thicknesses have shown nearly the same values. The results observed in this study are in striking contrast to those from isothermal crystallization in bulk, as observed byHoffman andWeeks. The constancy of the thickness of solution-grown crystals is interpreted as that the longitudinal translation of chains and chain ends in the interior of a crystal, necessary to thickening, will have been restrained on account of a considerably lower crystallization temperature than that in bulk. The lamellar thickness observed is presumed to have nearly equal value to the thickness of the growth nucleus as derived from the kinetic theory byLauritzen andHoffman.

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Zusammenfassung Es wurden Polyäthylen-Einkristalle isotherm aus 0,1%iger Lösung in Tetralin bei 77,2, 84,8 und 89,8 °C und aus n-Hexadecane (106,6 °C) hergestellt, und es wurden die Lamellendicken als Funktion der Kristallisationszeit untersucht. Diese Kristalle haben keine Änderung gezeigt oder, wenn, dann nur eine sehr geringfügige Änderung der Dicke. Sogar für Kristalle bei beträchtlich höherer Temperatur, erzeugt bei 106,6 °C, bei der die Segmentbeweglichkeit in den Kristallen aktiv zu werden beginnt, war der Anstieg der Lamellendicken nur von der Größenordnung 10 Å. Wenn Polyäthylenfraktionen von verschiedenen Molekulargewichten bei derselben Temperatur kristallisiert wurden, zeigten die Lamellendicken nahezu dieselben Werte. Die beobachteten Ergebnisse sind in schlagendem Kontrast zu denjenigen isothermer Kristallisation aus der Masse, wie sie beiHoffman undWeeks beobachtet wurden. Die Konstanz der Dicke von lösungsgewachsenen Kristallen wird damit interpretiert, daß die longitudinale Translation der Ketten und Kettenenden im Inneren eines Kristalls, notwendig zum Dicken-Wachstum, infolge der beträchtlich langsameren, niedrigeren Kristallisationstemperaturen als bei Kristallisation in der Masse stark behindert ist. Die beobachteten Lamellendicken haben nahezu den gleichen Wert wie die Dicke des Wachstumskeims, wie er sich aus der kinetischen Theorie vonLauritzen undHoffman ableilet.

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With 1 table     

Syntheses of polythia[n]ruthenocenophanes

Thiacrown ethers containing ruthenocene as a subunit were synthesized by the reaction of 1,1′-bis(3-chloropropyl-1-thia)ruthenocene with disodium dithiolates in THF/EtOH. In these reactions, some unexpected products were obtained.     

A new route to 2-amino- or 2-hydroxy-3-pyridinecarboxylic acid derivatives

Schiff's bases derived from ketones and t-butylamine ( 1 ) reacted with methyl methoxymethylenemalonate to give 2-hydroxy-3-pyridinecarboxylates. Similarly, treatment of 1 with ethoxymethylenemalononitrile gave 2-amino-3-pyridinecarbonitriles. Compounds 1 on reaction with ethyl 2-cyano-3-ethoxypropenoate afforded 2-amino-3-pyridinecarboxylates.     

Total synthesis of the squalene synthase inhibitor zaragozic acid C

Zaragozic acids and squalestatins were documented by Merck, Glaxo, and Tokyo Noko University/Mitsubishi Kasei Corporation as part of a program aimed at identifying novel inhibitors of squalene synthase, as well as farnesyl transferase. These natural products have attracted considerable attention from numerous synthetic chemists because of their therapeutic potential and novel architecture. This review highlights our total syntheses of zaragozic acid C by two convergent strategies. The key steps in our first-generation synthesis involve 1) simultaneous creation of the C4 and C5 quaternary stereocenters through the Sn(OTf)2-promoted aldol coupling reaction between the alpha-keto ester and silyl ketene thioacetal derived from L- and D-tartaric acids, respectively; and 2) construction of the bicyclic core structure via acid-catalyzed internal ketalization under kinetically controlled conditions. The second-generation strategy relies on a tandem carbonyl ylide formation/1,3-dipolar cycloaddition approach and features elongation of the C1 alkyl side chain through an olefin cross-metathesis as well as high convergency and flexibility.