Agariblazeispirols A and B, an unprecedented skeleton from the cultured mycelia of the fungus, Agaricus blazei

Agariblazeispirols A and B, which have a unique steroidal skeleton, have been isolated from the cultured mycelia of Agaricus blazei (Agaricaceae). The absolute structure of Agariblazeispirol A was established to be (20S,22R,23R,24S)-13β,22:22,25-diepoxy-5-methoxy-14β-methyl-18-nor-des-A-ergosta-5,7,9,11-tetraen-23-ol by extensive 1D and 2D NMR spectral data, and X-ray analysis. The structure of Agariblazeispirol B was elucidated to be a stereoisomer of agariblazeispirol A at its carbon 22, (20S,22S,23R,24S)-13β,22:22,25-diepoxy-5-methoxy-14β-methyl-18-nor-des-A-ergosta-5,7,9,11-tetraen-23-ol by comparison of extensive 1D and 2D NMR spectral data with those of agariblazeispirol A. Both compounds showed a moderate circumvention of drug resistance on mouse leukemia P388/VCR cells.     

Angular heterocycles. A convenient synthesis of azabenzophenothiazines

The acid-catalysed reaction of substituted 1,4-naphthoquinones with o-aminoheterocyclic thiones in alcoholic solution afforded substituted monoazabenzo[a]phenothiazin-5-ones 4,5 and substituted benzo[a][1,4]diazabenzothiazino[3,2-c]phenothiazin-5-one ( 6 ). Some of the resulting compounds were subjected to dehalogenation. The structures of the products were assigned by elemental analysis, ¹H-nmr, and other spectral analysis.     

Reliable and fast allele-specific extension of 3'-LNA modified oligonucleotides covalently immobilized on a plastic base, combined with biotin-dUTP mediated optical detection.

In the present work, a convenient microarray SNP typing system has been developed using a plastic base that covalently immobilizes amino-modified oligonucleotides. Reliable SNP allele discrimination was achieved by using allelic specificity-enhanced enzymatic extension of immobilized oligonucleotide primer, with a locked nucleic acid (LNA) modification at the SNP-discriminating 3'-end nucleotide. Incorporation of multiple biotin-dUTP molecules during primer extension, followed by binding of alkaline phosphatase-conjugated streptavidin, allowed optical detection of the genotyping results through precipitation of colored alkaline phosphatase substrates onto the surface of the plastic base. Notably, rapid primer extension was demonstrated without a preliminary annealing step of double-stranded template DNA, allowing overall processes to be performed within a couple of hours. Simultaneous evaluation of three SNPs in the genes TGFB1, SOD2 and APEX1, previously investigated for association with radiation sensitivity, in 25 individuals has shown perfect assignment with data obtained by another established technique (MassARRAY system).     

End-cap exchange of rotaxane by the Tsuji-Trost allylation reaction

[reaction: see text] Rotaxanes possessing a cinnamyl ester group at the axle terminal were prepared. The terminal end-cap was modified with a bulky malonate ester in excellent yield by the Tsuji-Trost allylation reaction, which was carried out in the presence of a palladium catalyst.     

Determination of isoniazid in tablets by second-derivative ultraviolet spectrophotometry of scraped-spot solutions from thin-layer chromatography

Isoniazid in solutions of tablets was separated by thin-layer chromatography (TLC). The portion of the precoated plate carrying the isoniazid spot was cut out and the coating was scraped off into water. The isoniazid was quantified in the solution, without separation of suspended adsorbent, by second-derivative spectrophotometry, which eliminated the background in the zero-order spectra. Relative standard deviations (n = 5) were <1%. Results obtained for commercial tablets were in good agreement with those given by a liquid-chromatographic method.     

A novel technique for observing the internal ultrastructure of human chromosomes with known karyotype

Observation of the internal ultrastructure of human chromosomes by transmission electron microscopy (TEM) has frequently been attempted in spite of the difficulties in detaching metaphase chromosome spreads from the glass slide for further processing. In this study we have used a method in which metaphase chromosome spreads were prepared on a flexible thermoplastic membrane (ACLAR) film. To assess chromosome identity, a diamidino-phenylindole staining and karyotying was first done using a conventional cytogenetic system. The chromosome spreads were then fixed with 1% osmium tetroxide, stained with freshly prepared 2% tannic acid, dehydrated, and flat-embedded in epoxy resin. The resin sheet was easily detachable and carried whole chromosome spreads. By this method, TEM observation of chromosomes from normal human lymphocytes allowed a thorough examination of the ultrastructure of centromeres, telomeres, fragile sites, and other chromosomal regions. Various ultrastructural patterns including thick electron dense boundaries, less dense internal regions, and extended chromatin loops at the periphery of the chromosomes were discernible. Application of the present method to chromosome research is expected to provide comprehensive information on the internal ultrastructure of different chromosomal regions in relation to function.     

Electric-field dependent electron mobility in anthracene single crystals

We observed the electric-field dependence of electron drift velocity in the c′ direction of anthracene single crystals at low temperature and found out that it tends to almost constant value above the electric-field of 1.8 × 10⁵ V cm^-1 at 140 K deviating from the linear proportionality to the field below this value. This result may be regarded as an experimental verification for the recent theoretical prediction by Sumi.     

Condensation of 2H-indazole-4,7-dione derivatives with 2-aminophenol derivatives

A new type of 9-substituted-5-methyl-2-phenyl-4H-pyrazolophenoxazin-4-one derivatives was prepared by the condensation of 5-methyl- and 6-methyl-2-phenyl-2H-indazole-4,7-diones with 4-substituted-2-aminophenols in pyridine. Relative reactivity of 2-aminophenol derivatives in the condensation was studied.     

Double 1,3-dipolar cycloadditions of meso-ionic heterocycles to N-substituted maleimides

Double 1,3-dipolar cycloadditions of 2,4-diphenyl-3-methyloxazotium 5-oxide and 3-phenylsydnone to two molecules of N-substituted maleimide afforded one or two isomeric 4,8-iminobenzo[1,2-c:4,5-c′]dipyrrole-1,3,5,7-tetrone derivatives owing to the types of heterocycles as well as N-substituents of maleimides.