Synthesis of poison-frog alkaloids 237D, 207A, and two congeners of 235B' for evaluation to inhibitory effect of nicotinic acetylcholine receptors

Enantioselective synthesis of the poison-frog alkaloids 237D, 207A, and two congeners of 235B' has been achieved. The absolute stereochemistry of 237D was determined to be 5S, 8S, 9R by the present synthesis.     

Synthesis and inhibitory effect of novel glycyrrhetinic acid derivatives on IL-1 beta-induced prostaglandin E(2) production in normal human dermal fibroblasts

Olean-11,13(18)-dien-3beta,30-diol dihemiphthalate (3), which was derived from glycyrrhetinic acid (GA), has been reported to produce a potent of anti-inflammatory effect in in vivo assays. Using 3 as a lead compound, we attempted to synthesize some modified compounds which varied in the following; i) the position of a carboxyl group in the phthalate moiety, ii) the number of carboxyls attached to the benzoyl group, iii) conversion of benzene ring to another ring system, iv) the linkage form between the benzene ring and oleanene skeleton at position 3 and/or 30. These were screened for their inhibitory activity against interleukin-1 beta (IL-1 beta)-induced prostaglandin E(2) (PGE(2)) production in normal human dermal fibroblasts (NHDF). Although conversion of the ortho-carboxyl group of 3 into the meta-position or the para-position led to an increase in inhibitory activity, the elimination or increase of the carboxyl group resulted in loss of the inhibitory activity. Conversion of the ester bond to the amide bond at position 3 and/or 30 of 3 did not contribute to a significant increase in inhibitory activity. On the other hand, among the derivatives possessing an anthranilic acid moiety at position 30 of 3beta-O-acetyl-olean-11,13(18)-dien-30-oic acid (20), 3beta-hydroxy-30-nor-olean-11,13(18)-dien-20 beta-[N-(2-carboxyphenyl)]carboxamide (30) showed the most potent inhibitory activity (IC(50) 1.0 microM) in this series.     

On the logarithmic plurigenera of complements of plane curves

Let B be a (not necessarily irreducible) plane curve in ². In the present article, we prove that if and only if Moreover, we determine the curve B when and Mathematics Subject Classification (2000): 14R05, 14H50, 14J26     

Invariability,hesitation or restoration of damage in wet-dry fatigue process

The effects of corrosive wet conditions on the progress of fatigue were studied by means of wet-dry two-stage tests of same stress level. Some results from the two-state tests—invariability, hesitation, etc., during the progress of fatique fracture—are discussed on the basis of results of measurements made on corrosionfatigue cracks and anlaysis by the equations of crack propagation. Several new methods for measurement of corrosionfatigue cracks were developed for this purpose.     

Effects of degree of crystallinity upon dielectric behaviors in some aromatic Polyesters

Zusammenfassung An vier polymerhomologen Reihen von Oligomeren des Nylon 6-, Nylon 66- und Polyurethantyps wurde der Einfluß einer Temperaturvorbehandlung, der Phenolquellung und der Kristallisationsbedingungen auf die Langperiode röntgenographisch untersucht. Es wurde der Polymerisationsgrad festgestellt, bei dem die Oligomeren der vier Reihen erstmalig moleküllängenunabhängige Langperioden nach Art der vonHeß undKießig in Röntgenogrammen von Polyamiden und Polyestern entdeckten Kleinwinkelinterferenzen liefern.Das Auftreten vonHeß-Kießig-Reflexen in denKratky-Diagrammen der höheren Oligomeren wird durch Kettenüberfaltung erklärt.XXVII. Mitt. über Oligomere. XXVI. Mitt. vgl.Zahn, H., J. Kunde undG. Heidemann, Makromol. Chem.43, 220 (1961).Dem Andenken anKurt Heß gewidmet.Wir danken dem Bundeswirtschaftsministerium (Forschungsvorhaben J 272), dem Fonds der Chemischen Industrie, Düsseldorf, sowie der Deutschen Forschungsgemeinschaft, Bad Godesberg, für die Förderung dieser Arbeit.     

Iodine catalyzed reduction of arenesulfonic acid to the arenethiol with triphenylphosphine

Arenesulfonic acids, its sodium salts, and alkyl arenesulfonates were reduced readily to the corresponding arenethiols quantitatively with triphenylphosphine in the presence of iodine.