During our search for new antibiotics, in vitro antiviral activity was detected in the crude broths and its butanol extracts of a strain of Penicillium turbatum (WESTLING). Penicillium turbatum was isolated from a soil obtained from Mt. Ararat in Eastern Turkey and has been assigned the number NRRL 5630. The components responsible for the antiviral activity were found to be members of the epipolythiopiperazinedione antibiotics*.

In the AD brain, there are elevated amounts of soluble and insoluble Aβ peptides which enhance the expression of membrane bound and soluble receptor for advanced glycation end products (RAGE). The binding of soluble Aβ to soluble RAGE inhibits further aggregation of Aβ peptides, while membrane bound RAGE-Aβ interactions elicit activation of the NF-κB transcription factor promoting sustained chronic neuroinflammation. Atomic force microscopy observations demonstrated that the N-terminal domain of RAGE, by interacting with Aβ, is a powerful inhibitor of Aβ polymerization even at prolonged periods of incubation. Hence, the potential RAGE-Aβ structural interactions were further explored utilizing a series of computational chemistry algorithms. Our modeling suggests that a soluble dimeric RAGE assembly creates a positively charged well into which the negative charges of the N-terminal domain of dimeric Aβ dock.

In this chapter, we attempt to analyze the evolution of the amyloid-beta (Abeta) molecular structure from its inception as part of the Abeta precursor protein to its release by the secretases and its extrusion from membrane into an aqueous environment. Biophysical studies suggest that the Abeta peptide sustains a series of transitions from a molecule rich in alpha-helix to a molecule in which beta-strands prevail. It is proposed that initially the extended C-termini of two opposing Abeta dimers form an antiparallel beta-sheet and that the subsequent addition of dimers generates a helical Abeta protofilament. Two or more protofilaments create a strand in which the hydrophobic core of the beta-sheets is shielded from the aqueous environment by the N-terminal polar domains of the Abeta dimers. Once the nucleation has occurred, the Abeta filament grows in length by the addition of dimers or tetramers.

The three-dimensional structure of the Alzheimer's disease Abeta1-42 peptide was predicted by sequence homology, threading approaches and by experimental observations. The Abeta molecule displayed a Greek key motif with four antiparallel beta-strands. To shield thermodynamically unfavorable domains, two Abeta molecules interact with each other to generate a beta-barrel structure with a hydrophilic surface and a hydrophobic core. The N-terminal domains of the dimer form crevices into which the non-polar C-termini are accommodated to yield a globular structure 27x32 A in diameter. Alternatively, the C-terminal domains of two opposing dimers could be extended to form an antiparallel beta-sheet. The stacking of these building blocks generates a helical protofilament. To create a thermodynamically more favorable structure, three protofilaments associate into a right-handed triple helix with a hydrophobic beta-sheet completely surrounded by the hydrophilic beta-barrels made of residues 1-28. Two triple helical strands can further associate into a right-handed amyloid filament. Although our model did not meet all the expected criteria, it nevertheless exhibited a series of naturally disposed structural features, revealed by other biophysical studies utilizing synthetic Abeta peptides. These characteristics are of functional significance in terms of Abeta-topology, fibril formation and cytotoxicity. The model also suggests that Abeta may not exist in a thermodynamically stable conformation, but rather as an ensemble of metastable dimeric structures some of which are capable of generating an extended C-terminal antiparallel beta-sheet essential in the promotion of fibrillogenesis.

Molecular dynamics simulations of leukotriene C4 (LTC4), leukotriene D4 (LTD4), and leukotriene E4 (LTE4) were carried out, and the data were visualized in an animated video format. Three-dimensional ghost images show the positions of the heavy atoms of all three molecules throughout the simulations. The ghost images can be superimposed to give a single three-dimensional image in which the shapes of the most populated conformers of each molecule are apparent and can be compared. Leukotriene D4 was found to occupy mostly T-shaped conformations, while LTC4 occupied mostly cup-shaped conformations, and LTE4 occupied a wide range of conformations spanning the LTD4 and LTC4 types. Digital filtering and graphing of the internal geometries of the molecules as a function of time revealed differences in dynamic behavior. The results are discussed in light of current knowledge about leukotriene receptors.

The expression of the carboxyl-terminal 100 (C-100) residues of the amyloid precursor protein (APP) may provide a model for studying the processing of APP to the 42-43 residue beta-amyloid peptide (beta A4) implicated in Alzheimer's disease. Expression of human C-100 in mammalian cells reportedly causes 'toxicity' and amyloid-like fibrils. We have expressed the C-100 fragment in human embryonic kidney cells (293 cells) in a transient assay and compared it to the expression of transfected wild type and mutant (Swedish familial Alzheimer's disease) full length APP Products were characterized by Western blot analysis using antibodies to the carboxyl-terminal region of APP.

A series of lipophilic benzophenone dicarboxylic acids have been shown to be inhibitors of the binding of LTB4 to its receptors on intact human neutrophils (Gapinski et al. (1990). Structure-activity relationships indicated that maximum activity was achieved when an acid group was attached at the meta position of each ring. In this report, the conformation of these inhibitors that binds best to the LTB4 receptor was determined. Inhibition concentration profiles of four rigid xanthone isomers that mimicked the four major conformational states of this type of benzophenone dicarboxylic acid were compared. LY264086, 3-[4-[7-carboxy-3-[decyloxy]-9-oxo-9H-xanthene]]propanoic acid, was the most potent inhibitor. The distance between the two carboxyl groups in this isomer was found to be 9.8 angstrom, implying that the two acid binding sites on the receptor are separated by similar dimensions. Molecular modeling studies with low energy conformers of the xanthone isomers and LTB4 suggested a configuration of the agonist when it is bound to the receptor but did not exclude all other possibilities. These experiments further support the existence of two acid-binding sites on the human neutrophil LTB4 receptor.

Neuritic plaque and cerebrovascular amyloid deposits have been detected in the aged monkey, dog, and polar bear and have rarely been found in aged rodents (Biochem. Biophy. Res. Commun., 12 (1984) 885-890; Proc. Natl. Acad. Sci. U.S.A., 82 (1985) 4245-4249). To determine if the primary structure of the 42-43 residue amyloid peptide is conserved in species that accumulate plaques, the region of the amyloid precursor protein (APP) cDNA that encodes the peptide region was amplified by the polymerase chain reaction and sequenced. The deduced amino acid sequence was compared to those species where amyloid accumulation has not been detected. The DNA sequences of dog, polar bear, rabbit, cow, sheep, pig and guinea pig were compared and a phylogenetic tree was generated. We conclude that the amino acid sequence of dog and polar bear and other mammals which may form amyloid plaques is conserved and the species where amyloid has not been detected (mouse, rat) may be evolutionarily a distinct group. In addition, the predicted secondary structure of mouse and rat amyloid that differs from that of amyloid bearing species is its lack of propensity to form a beta-sheeted structure. Thus, a cross-species examination of the amyloid peptide may suggest what is essential for amyloid deposition.

To better understand the processing of the Alzheimer disease amyloid precursor protein, we have cloned and sequenced that region of the human genome coding for the amyloid peptide. Two exons separated by a 6.2kb intron define this region. Characterization of the A4 peptide amino acid sequence shows similarity to the structure of soybean trypsin inhibitor (Kunitz). Our observation describes a different region of PreA4 than the previously characterized domain of larger amyloid precursor molecules PreA4 751 and 770(2). Moreover, the exon organization, Kunitz domain duplication and transmembrane location of A4 suggest that PreA4 is similar to growth factor precursors and thus may be processed similarly.

The chiral compounds (R)- and (S)-N-(p-tolylsulfonyl)benzenesulfonimidamide have been prepared efficiently from N-(p-tolylsulfonyl)benzenesulfonimidoyl chloride and both enantiomers were transformed into chiral selenium diimide reagents, (S)- and (R)-N,N′-bis[N-(p-tolylsulfonyl)benzenesulfonimidoyl]selenium diimide, respectively, for the asymmetric allylic amination of olefins. Asymmetric allylic amination of methylenecyclohexane with the S-configured selenium diimide reagent afforded allylic amide, (1S)-N-[(R)-N-(p-tolylsulfonyl)benzenesulfonimidoyl]-2-methylenecyclohexylamine as a major diastereomer (42% diastereomeric excess). Similarly, cyclohexene, 1-heptene, and cyclooctene gave chiral allylic amides with 34%, 32%, and 20% diastereomeric excess, respectively. It is apparent that the S-configured diimido selenium reagent gives S-configured allylic amides, and that the R-configured reagent affords R-configured allylic amides as the major diastereomers in all of the cases investigated.

The structure of antibiotic A33853, isolated from the culture broth ofStreptomyces sp., NRRL 12068, is reported. The structure was deduced from an X-ray crystallographic study of its tetraacetyl derivative. Tetraacetyl A33853 is unique because it contains an anhydride moiety, an unexpected product from the reaction of A33853 with acetic anhydride and pyridine.

The levels of antidopaminergic and anticholinergic activities of neuroleptics, 4-piperazinyl-10H-thienobenzodiazepines, are modulated by imposing steric impedence to the piperazine ring. The optimum situation in favor of the anticholinergic action is reached in compound 5, 2,3-dimethyl-7-fluoro-4-(4-methyl-1-piperazinyl)-10H-thieno[2,3-b][1,5]benzodiazepine, where a maximum activity (equivalent to hyoscine), as measured by the [3H]QNB receptor binding assay, is obtained. The structure-activity relationships found highlight the importance of certain spatial dispositions of the distal piperazine nitrogen (electron lone pair) with respect to the tricyclic system. The evidence for molecular topography of these compounds is presented from X-ray, NMR, and other physical data. The conformational aspects for correspondence to the relevant receptors are discussed.

A novel low-molecular weight inhibitor of an aminoglycoside-inactivating enzyme, initially isolated from fermentation broths of Streptomyces neyagawaensis, was determined to be 7-hydroxytropolone. Its structure was confirmed by synthesis. In vitro synergy was demonstrated between 7-hydroxytropolone and certain aminoglycosides against bacteria which were resistant to those aminoglycosides by virtue of a 2"-O-adenylyltransferase. The synthesis and characterization of some analogs of 7-hydroxytropolone is also described.

5-O-Mycarosyltylactone has been isolated as a predominant factor from fermentation broths of a Streptomyces fradiae mutant. The relative configurations of mycarose and tylactone (protylonolide) have been determined by X-ray crystal structure analysis. Hydrolysis of 5-O-mycarosyltylactone yielded (-)-tylactone and L-(-)-mycarose. Taken together, these two experiments establish the absolute configuration of (-)-tylactone. Bioconversion of (-)-tylactone to tylosin by tyl G mutants of S. fradiae proves the absolute configuration of tylosin. Physicochemical data for tylactone and a unique component piece of tylactone are also reported.

AbstractGemäß Formelbild erhält man das Phenylketon (III), das zu den Oximen (IV) und (V) in 48%iger Ausbeute umgesetzt wird.

It is proposed, based upon comparisons with apomorphine, that the rigid pyrroleethylamine moiety of the ergolines is the portion of the molecule responsible for dopamine agonist activity. In support of this hypothesis, bicyclic and tricyclic ergoline partial structures 6, 11, 25, and 35 have been synthesized. In addition, some pyrazole isosters (37, 38, 40, and 45) of these rigid pyrroleethylamines have been made. All of the classes show dopaminergic activity in prolactin inhibition and in lesioned rat turning assays. The most potent drugs, the linear tricyclic pyrazoles 38 (R = Pr) and 40 (R = Pr), are comparable in potency with the highly active ergoline pergolide (41).

The synthesis and antirhinovirus activity of syn and anti isomers of 6-[[(hydroxyimino)phenyl]methyl]-1-[(1-methylethyl)sulfonyl]-1H-benzimidazol-2-amine (4 and 5) are reported. The structural assignments of 4 and 5 are based upon 13C NMR spectra of both isomers and also X-ray analysis of 5. The anti-isomer 5 was more potent than the syn-isomer 4 when compared as an inhibitor of rhinovirus multiplication in vitro. Both isomers inhibited multiplication of 15 different serotypes of rhinovirus.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew rearrangement of penicillin sulfoxideT. S. Chou, W. A. Spitzer, D. E. Dorman, S. Kukolja, I. G. Wright, N. D. Jones, and M. O. ChaneyCite this: J. Org. Chem. 1978, 43, 20, 3835–3837Publication Date (Print):September 1, 1978Publication History Published online1 May 2002Published inissue 1 September 1978https://pubs.acs.org/doi/10.1021/jo00414a009https://doi.org/10.1021/jo00414a009research-articleACS PublicationsRequest reuse permissionsArticle Views120Altmetric-Citations10LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

AbstractAus dem Indanoxid (I) erhält man das Azo‐diepoxid (IV), das Stickstoff unter Bildung des symm. Oxepinoxids (V) eliminiert.