Isoindole derivatives from 2-isonicotinoyl-acetophenone with ammonia and its derivatives

2-Isonicotinoylacetophenone (1) reacts with aqueous ammonia in the presence of acid to produce the deep blue 3-(4-pyridyl)-1-[3-(4-pyridyl)-1H -1-isoindolylidenemethyl]-2H-isoindole which changed to the deep bluish green adduct showing the wavelength maximum at 744 nm by treating with methyl iodide. From the reaction of 1 and glycine or its methyl ester the red 3,3′-di-(4-pyridyl)-1,1′-vinylenebis(2H-2-isoindoleacetic acid) or its derivative were obtained respectively.     

Synthesis of 4H-pyrazolo- and 4H-pyrrolophenothiazin-4-one derivatives

5-Methyl- and 6-methyl-2-phenyl-2H-indazole-4,7-diones were condensed with 2-aminobenzenethiol or 6-substituted-3-aminopyridine-2(1H)thiones 4 to produce a new type of 5-methyl-2-phenyl-4H-pyrazolophenothiazin-4-ones or 8-substituted-7-aza-5-methyl-2-phenyl-4H-pyrazolophenothiazin-4-one derivatives. From 6-bromo-2,5-dimethyl-1,3-diphenyl-2H-isoindole-4,7-dione and 4 8-substituted-7-aza-2,5-dimethyl-1,3-diphenyl-4H-pyrrolophenothiazin-4-one derivatives were also prepared.     

Suramin is a Novel Activator of PP5 and Biphasically Modulates S100-Activated PP5 Activity

Suramin is an activator of ryanodine receptors and competitively binds to the calmodulin-binding site. In addition, S100A1 and calmodulin compete for the same binding site on ryanodine receptors. We therefore studied the effects of suramin on protein phosphatase 5 (PP5) and S100-activated PP5. In the absence of S100 proteins, suramin bound to the tetratricopeptide repeat (TPR) domain of PP5 and activated the enzyme in a dose-dependent manner. In the presence of S100A2/Ca²⁺, lower concentrations of suramin dose-dependently inhibited PP5 activity as an S100 antagonist, whereas higher concentrations of suramin reactivated PP5. Although the C-terminal fragment of heat shock protein 90 (HspC90) also weakly activated PP5, the binding site of suramin and HspC90 may be different, and addition of suramin showed no clear effect on the phosphatase activity of PP5. Similar biphasic effects of suramin were observed with S100A1-, S100B- or S100P-activated PP5. However, the inhibitory effects of lower concentrations of suramin on S100A6-activated PP5 are weak and high concentrations of suramin further activated PP5. SPR and the cross-linking study showed inhibition of the interaction between S100 protein and PP5 by suramin. Our results revealed that suramin is a novel PP5 activator and modulates S100-activated PP5 activity by competitively binding to the TPR domain.     

Instrumental neutron activation analysis for assessing homogeneity of a whole rice candidate reference material

A whole rice reference material was prepared for use in quality control of trace elements in rice and in similar matrices. This study aimed at evaluating the homogeneity of the material. As, Br, Co, Cs, Fe, K, Na, Rb and Zn were determined in the samples by instrumental neutron activation analysis. The material is homogeneous for the elements determined (p < 0.05), except for Co and Fe, which presented dispersion of results much higher than the predicted degree of repeatability.     

Reversed-phase ion-pair liquid chromatographic method for determination of reaction equilibria involving ionic species: exemplification of the method using ligand substitution reactions of ethylenediaminetetraacetatochromium(III) ion with acetate and phosphate ions

A reversed-phase ion-pair liquid chromatographic method is presented for the determination of reaction equilibria involving ionic species of the same charge sign as reactant and product compounds. It has been demonstrated that ion-exchange chromatography or reversed-phase ion-pair chromatography is a useful tool for the determination of equilibrium constants of chemical reactions involving ionic species such as metal complexation reactions. Previous work with these methods has been based on the assumption that the limiting retention factors of the reactant and product species are constant independent of concentration of the chemical species (X) in the mobile phase, which reacts with the analyte compound. However, when all the reactant and product species are ions of the same charge sign as that of the species X, it is virtually impossible to apply these methods to the equilibrium constant determination because the retention factors of both the reactant and product species may depend on the concentration of X. In this study, an alternative approach was developed that estimates the limiting retention factors of ionic species from the dependence of the retention factor on the ionic strength of the mobile phase. Ligand substitution reactions of ethylenediaminetetraacetatochromium(III) ion with acetate and phosphate ions were used as model reactions to test this method. The equilibrium constants determined by this method are in good agreement with those obtained by a UV-visible spectrophotometric method.     

Reaction mechanism of hydroxymaleimide induced by γ-irradiation in alcohol solvents

Methanol and 2-propanol solutions of hydroxymaleimide were irradiated with γ-ray and mechanism of its γ-irradiation-induced reactions was investigated through final-product analyses using high performance liquid chromatography (HPLC) coupled with mass spectroscopy. An addition reaction of a solvent radical toward hydroxymaleimide was dominant among its oxygen-free γ-irradiation-induced reactions in its alcohol solutions while it is known that electron attachment toward hydroxyphthalimide or hydroxysuccinimide is dominant among their γ-irradiation-induced reactions. The radical adduct abstracts hydrogen from solvent molecule to re-produce a solvent radical. Therefore, the degradation efficiency of hydroxymaleimide was more than ten times larger than that of hydroxyphthalimide and hydroxysuccinimide. Dimer was also produced through electron attachment process in the solutions of hydroxymaleimide. In addition, it was found that the degradation efficiency increased with decrease in dose rate. An additional reaction of a solvent radical toward hydroxymaleimide competes with a radical–radical recombination. The latter was reduced, with the former leading to efficient degradation of hydroxymaleimide increased by irradiation at lower dose rate. On the contrary, the production yield of the adduct radical as well as the degradation efficiency of hydroxymaleimide was inhibited in the presence of oxygen.     

Products formed by the reaction of o-diacylbenzenes with primary amines

The reactions of o-diacylbenzenes with primary amines or ammonia produced several isoindole derivatives in the presence or the absence of acid. From o-diacylbenzenes and hydroxylamine hydrochloride in the presence of triethylamine 1H-2,3-benzoxazine derivatives were obtained.     

Agariblazeispirol C from the cultured mycelia of the fungus, Agaricus blazei, and the chemical conversion of blazeispirol A

Agariblazeispirol C, which has a unique steroidal skeleton, has been isolated from the cultured mycelia of Agaricus blazei (Agaricaceae). The structure of agariblazeispirol C was established to be (23S,24S)-13,23-cyclo-25-hydroxy-14β-methyl-18-nor-des-A-ergosta-5,7,9,11,17(20)-pentaen-22-one by comparison of extensive 1D and 2D NMR spectral data with those of agariblazeispirols A and B. At the same time, agariblazeispirol C was synthesized by the reaction of blazeispirol A with BF₃·OEt₂ along with some interesting compounds.