Multielement determination in tobacco leaves by photon activation analysis

A nondestructive photon activation procedure with 30 MeV bremsstrahlung followed by high-resolution gamma-spectrometry has been applied to the multielement determination in tobacco leaves and commercial cigarettes. The elements determined by this method included essential minor elements such as Ca, Cl, K and Mg, essential trace elements such as Fe, Mn and Zn, and possibly toxic elements such As and Sb. The NBS Orchard Leaves could successfully be used as a comparative standard. The method is quite simple and gives good reproducible results for at least 12 elements.     

Design and synthesis of highly sensitive and selective fluorescein-derived magnesium fluorescent probes and application to intracellular 3D Mg2+ imaging

The role of intracellular magnesium ions is of high interest in the fields of pharmacology and cellular biology. To accomplish the dynamic and three-dimensional imaging of intracellular Mg2+, there is a strong desire for the development of optimized Mg2+ fluorescent probes. In this paper we describe the design, synthesis, and cellular application of the three novel Mg2+ fluorescent probes KMG-101, -103, and -104. The compounds of this series feature a charged beta-diketone as a binding site specific for Mg2+ and a fluorescein residue as the fluorophore that can be excited with an Ar+ laser such as is widely used in confocal scanning microscopy. This molecular design leads to an intensive off-on-type fluorescent response toward Mg2+ ions. The two fluorescent probes KMG-103 and -104 showed suitable dissociation constants (Kd,Mg2+ = 2 mM) and nearly a 10-fold fluorescence enhancement over the intracellular magnesium ion concentration range (0.1-6 mM), allowing high-contrast, sensitive, and selective Mg2+ measurements. For intracellular applications, the membrane-permeable probe KMG-104AM was synthesized and successfully incorporated into PC12 cells. Upon application of the mitochondria uncoupler FCCP to the probe-incorporated cells, the resulting increase in the free magnesium ion concentration could be followed over time. By using a confocal microscope, the intracellular 3D magnesium ion concentration distributions were satisfactorily observed.     

Antitumor and immunomodulating activities of a beta-glucan obtained from liquid-cultured Grifola frondosa

The effects of the beta-1,3-glucan, LELFD, obtained from liquid-cultured mycelium of Grifola frondosa, on the growth of syngeneic tumors and immune responses in mice were examined. In Meth A or IMC solid tumor systems, LELFD administered intraperitoneally (i.p.) or intralesionally (i.l.) exhibited significant antitumor effects. However, the growth of L1210 and P388 leukemias was unaffected by the injection of LELFD. The injection of LELFD i.p. enhanced the activities of natural killer cells and macrophages in mice. LELFD also enhanced the antibody response when it was injected i.p. with sheep red blood cells into mice. Furthermore, it was found that LELFD could activate the alternative complement pathway.     

Voltammetric investigation of avidin-biotin complex formation using an electroactive bisbiotinyl compound

Formation of avidin-biotin complex was investigated using bisbiotinyl thionine (BBT) by means of voltammetric techniques. Thionine is an electroactive compound and has two amino groups that are necessary for the reaction with a biotinylation reagent. The biotinylation of thionine produces a new reagent with two biotin moieties at each end of thionine. Three BBTs of different lengths of the spacer that connects the biotin moiety to the thionine moiety were prepared. The avidin-biotin binding assay was achieved by measuring the electrode response of the thionine moiety in BBT. The binding affinity and the conformation of complex, which depended on the length of spacer, are discussed. BBT in which the spacer is shortest (BBT-S, distance between carbonyl group of the two biotin moieties: 11 Å) binds with only one avidin molecule. BBT with medium length of spacer (BBT-M, 28.8 Å) forms the complex with two avidin molecules. BBT with the longest spacer (BBT-L, 46.6 Å) allows binding with two avidin molecules as well as intramolecular binding within one avidin molecule. The affinity constants of BBT-S, BBT-M and BBT-L for avidin were estimated to be 7.0 × 10¹² M⁻¹, 3.2 × 10¹² M⁻¹ and 4.0 × 10¹² M⁻¹, respectively.     

Facile construction and divergent transformation of polycyclic isoxazoles: direct access to polyketide architectures

[reaction: see text] Base-promoted cyclocondensation of C-chloro oximes with cyclic 1,3-diketones affords functionalized isoxazoles in good yield and under convenient reaction conditions. This process enables the synthesis of highly substituted products with notable functional group tolerance. The products obtained are directly converted to a variety of polyketide-derived polycyclic structures including xanthenes, anthracenes, and benzophenones.     

4,7‐Diiodo‐2,1,3‐benzothiadiazole and 7,7′‐diiodo‐4,4′‐bi(2,1,3‐benzothiadiazole)

In the crystal structures of the title compounds, C₆H₂I₂N₂S, (I), and C₁₂H₄I₂N₄S₂, (II), respectively, a large number of short inter‐heteroatom contacts, such as S?N, I?I and N?I, are observed. In (II), which is non‐centrosymmetric, two halves of the mol­ecule are related by a crystallographic twofold axis.     

Reversed-phase high-performance thin-layer chromatography of hematoporphyrin and its nickel,copper and zinc complexes

Summary The thin-layer chromatographic mobility of hematoporphyrin IX (Hp) and its metal complexes on octyl (C₈)- or octadecyl (C₁₈)-bonded silica gel plate is described. The mobility order for those compounds is regular on both kinds of plate with various compositions of methanol-phosphate buffer mixtures as the developing solvents; thus, Cu-complex < Ni-complex < Hp (free acid) < Zn-complex. The combination of a C₁₈-plate with an 85∶15 (vol/vol) mixture of methanol and phosphate buffer (pH 3) is recommended for the successful separation of these four compounds.     

Unexpected formation of benzaldehydes by the reactions of dithioacetals derived from cinnamaldehydes with 2,3-dichloro-5,6-dicyano-p-benzoquinone in aqueous solvents

1,3-Dithianes 1 , 1,3-dithiolanes 2 , and diphenyl dithioacetals 3 derived from cinnamaldehydes reacted with 2,3-dichloro-5,6-dicyano-p-benzoquinone in aqueous solvents to give benzaldehydes 4 . Hydride transfer from 1–3 to 2,3-dichloro-5,6-dicyano-p-benzoquinone followed by hydrolysis and oxidative carbon-carbon bond cleavage would produce benzaldehydes 4 .