Chichibabin “isodesmopyridine” synthesis

2,3,5-Trisubstituted pyridine isodesmopyridine is one of the elastin crosslinking amino acid which was isolated from the acid hydrolysates of bovine ligamentum nuchae. Biosynthesis of isodesmopyridine is believed to undergo via Chichibabin pyridine synthesis starting from aldehydes and an ammonia. Herein, we report the first total synthesis of isodesmopyridine through Chichibabin pyridine synthesis from allysines with protecting groups and ammonium salts in the presence of 50?mol% Pr(OTf)₃ with the optimization of the reaction conditions.     

Re-Evaluations of Zr-DFO Complex Coordination Chemistry for the Estimation of Radiochemical Yields and Chelator-to-Antibody Ratios of 89Zr Immune-PET Tracers

(1) Background: Deferoxamine B (DFO) is the most widely used chelator for labeling of zirconium-89 (⁸⁹Zr) to monoclonal antibody (mAb). Despite the remarkable developments of the clinical ⁸⁹Zr-immuno-PET, chemical species and stability constants of the Zr-DFO complexes remain controversial. The aim of this study was to re-evaluate their stability constants by identifying species of Zr-DFO complexes and demonstrate that the stability constants can estimate radiochemical yield (RCY) and chelator-to-antibody ratio (CAR). (2) Methods: Zr-DFO species were determined by UV and ESI-MS spectroscopy. Stability constants and speciation of the Zr-DFO complex were redetermined by potentiometric titration. Complexation inhibition of Zr-DFO by residual impurities was investigated by competition titration. (3) Results: Unknown species, ZrH_qDFO₂, were successfully detected by nano-ESI-Q-MS analysis. We revealed that a dominant specie under radiolabeling condition (pH 7) was ZrHDFO, and its stability constant (logβ₁₁₁) was 49.1 ± 0.3. Competition titration revealed that residual oxalate inhibits Zr-DFO complex formation. RCYs in different oxalate concentration (0.1 and 0.04 mol/L) were estimated to be 86% and >99%, which was in good agreement with reported results (87%, 97%). (4) Conclusion: This study succeeded in obtaining accurate stability constants of Zr-DFO complexes and estimating RCY and CAR from accurate stability constants established in this study.     

Friction coefficient for a moving disinclination in a nematic liquid crystal

The effective friction coefficient for sufficiently slow motions of a disinclination in nematic liquid crystal is calculated. The motion of a disinclination under the repulsive force due to the boundary wall is also discussed.     

Theory of anomalous ultrasonic absorption and dispersion of nematic liquid crystals just above the clearing point

The dynamic heat capacity of nematic liquid crystals just above the clearing point is calculated as an extension of our previous theory of static heat capacity. The present theory explains semi-quantitatively the available experimental results of anomalous ultrasonic absorption and dispersion.     

Selective preconcentration of rare earth elements by substoichiometric precipitation of calcium oxalate and its application to the neutron activation analysis of biological material

A preconcentration method for trace amounts of rare earth elements (REs) based on the substoichiometric precipitation of calcium oxalate was developed. RE(III) was quantitatively coprecipitated with calcium oxalate which had been precipitated from the calcium of a macrocomponent in a biological sample by addition of a substoichiometric amount of oxalate. In this way high selectivity for RE(III) from other elements was achieved. The method was applied to the neutron activation analysis of a biological sample (NBS SRM 1572 Citrus Leaves), and Sc, La, Ce, Pf, Nd, Sm, Eu, Th, Dy, Ho, Yb and Lu were determined with a relative standard deviation of less than 5%.     

Effect of alkyl substitueras in hydrophobic 8-quinolinol on the extraction of gallium(III) and applications to the separation of gallium(III) from aluminum(III)

The extraction of gallium(III) with newly prepared 5-alkyloxymethyl-8-quinolinol derivatives with alkyl substituent at the 2-position in 8-quinolinol moiety has been studied. The Ga(III)-5-octyloxymethyl-8-quinolinol (HO(8)Q), Ga(III)-2-methyl-5-octyloxymethyl-8-quinolinol (HMO(8)Q), Ga(III)-2-methyl-5-hexyloxymethyl-8-quinolinol (HM-O(6)Q), and Ga(HI)-2-n-butyl-5-hexyloxymethyl-8-quinolinol (HNBO(6)Q) complexes extracted in heptane from a perchloric acid medium were Ga(O(8)Q)(3), Ga(OH)(H(2)O)(MO(8)Q)(2), Ga(OH)(H(2)O)(MO(6)Q)(2) and Ga(OH)H(2)O)(NBO(6)Q)(2), respectively. The 2-tert-butyl-5-hexyloxymethyl-8-quinolinol did not exhibit any reactivity toward gallium(III). The extraction constants for Ga(O(8)Q)(3) (K(ex) = [Ga(O(8)Q)(3)](org) [H(+)](3)/[Ga(3+)][HO(8)Q](org)(3)), Ga(OH)(H(2)O)(MO(8)Q)(2) (K(ex) = [Ga(OH) (H(2)O)(MO(8)Q)(2)](org) [H(+)](3)/[Ga(3+)][HMO(8)Q](org)(2)), Ga(OH)(H(2)O)(2)(MO(6)Q)(2) and Ga(OH)(H(2)O)(NBO(6)Q)(2), which were extracted in heptane from an acidic solution, are 10(3.21 +/- 0.12), 10(-4.24 +/- 0.16), 10(-3.84 +/- 0.16) and 10(-4.07 +/- 0.07), respectively at I = 0.1 M and 25 degrees C. HNBO(6)Q exhibited very high selectivity toward gallium(III) in the presence of aluminum(III). Even in the presence of a 100 fold excess of aluminum(III) to gallium(III) (1.43 x 10(-5) M), gallium(III) was completely extracted and the distribution ratio of aluminum(III) was found to be less than 2.0 x 10(-3).     

Synergistic effect of heterocyclic bidentate amines on the extraction of thorium(IV) with 2-thenoyltrifluoroacetone

The synergistic effect on the extraction of thorium(IV) was found by the combination of 2-thenoyltrifluoroacetone (Htta) and 1,10-phenanthroline (phen) or 4,7-diphenyl-1,10-phenanthroline (dpp) as a neutral bidentate ligand. Especially in the presence of dpp (1·10^–3M) in benzene, the distribution ratio of thorium(IV) increased by a factor of about 300. Such synergistic enhancement of the extraction was ascribed to the formation of the adduct complex of Th(tta)₄(phen) and Th(tta)₄(dpp) in the organic phase. The extraction constant and the adduct formation constant were determined and discussed.     

Substoichiometric determination of inorganic tin in organotin compounds

Inorganic tin(IV) present in organotin compounds is determined substoichiometrically by complexation with salicylideneamino-2-thiophenol in a non-aqueous medium, after isolation of the tin(IV) by iodide extraction. The method is applied to the degradation products in commercial chemicals and those formed by u.v.-irradiation.     

Substoichiometric speciation for inorganic arsenic and methylated arsenic and its application to samples of marine organisms

A substoichiometric isotope-dilution method is described for the determination of monomethylarsonate, MeAs(V), and dimethylarsinate, Me₂As(V). After the separation of MeAs(V) and Me₂As(V) by extraction as their iodides into benzene, these methylated arsenic species are complexed with a substoichiometric amount of diethyldithiocarbamate in benzene, and the uncomplexed methylarsenic species are removed. The relative standard deviations for the substoichiometric extraction of MeAs(V) and Me₂As(V) are 0.55% and 1.1%, respectively. This substoichiometric speciation of methylated arsenic together with an earlier substoichiometric method for speciation of inorganic arsenic species was applied to the speciation of arsenic in an acid-digested solution of a macro-algae sample. It was demonstrated that almost all the arsenic in this solution was Me₂As(V) even after the digestion with nitric acid.     

Medicinal flowers. XXIII. New taraxastane-type triterpene, punicanolic acid, with tumor necrosis factor-alpha inhibitory activity from the flowers of Punica granatum

The methanolic extract from the flowers of Punica granatum L. (Punicaceae) was found to show inhibitory effect on tumor necrosis factor-alpha (TNF-alpha, 1 ng/ml)-induced cytotoxicity in L929 cells. By bioassay-guided separation, a new taraxastane-type triterpene, punicanolic acid (1), was isolated from the active fraction (ethyl acetate-soluble fraction) together with four triterpenes (2--5), two galloyl glucoses (6, 7), two flavones (8, 9), and beta-sitosterol. Among the constituents, 1, oleanolic acid (2), maslinic acid (4), 1,2,6-tri-O-galloyl beta-D-glucopyranoside (6), 1,2-di-O-galloyl-4,6-O-(S)-hexahydroxydiphenoyl beta-D-glucopyranoside (7), and luteolin (8) significantly inhibited TNF-alpha-induced cytotoxicity in L929 cells at 30 microM.