Shin'ichi Nakatsuji

High-performance liquid chromatography-fluorometry for the determination of thiols in biological samples using N-4-(6-dimethylamino-2-benzofuranyl)phenyl]-maleimide

The selective determination of thiols in biological samples was investigated by high-performance liquid chromatography using N-[4-(6-dimethylamino-2-benzofuranyl)phenyl] maleimide, which was found to give fluorescent products when treated with certain thiols. Six kinds of thiol (reduced glutathione, cysteine, N-acetylcysteine, cysteamine, homocysteine and coenzyme A) could be separated simultaneously within ca. 12 min and determined at final level of sensitivity. The method was successfully applied to the determination of thiols in rat tissues and plasma and in human normal serum.

A sensitive method for the fluorometric determination of lithium with a “crowned” benzothiazolylphenol

On mesure la fluorescence du phenolate du complexe Li/compose crown, obtenu par traitement a la methylamine

4-(t-butylthio)-3-buten-2-one. Synthon for α,β- and α,β,γ,δ-unsaturated aldehyde synthesis

Abstract A convenient synthesis of α,β- and α,β,γ,δ-unsaturated aldehydes using readily accessible 4-( t -butylthio)-3-buten-2-one as synthon was described.

A new fluorogenic thiol-selective reagent: N-{p-[2-(6-dimethylamino)benzofuranyl]phenyl}maleimide

N-{p-[2-(6-Dimethylamino)benzofuranyl]phenyl}maleimide (DBPM), has been synthesized and found to give fluorescent products when reacted with certain thiols. The reaction is very sensitive, and concentrations as low as 10(-9)M can be detected.

Diphenylmethane and triphenylmethane dye ethynovinylogues with absorption bands in the near-infrared1

Abstract Diphenylmethane and triphenylmethane dye ethynovinylogues (i.e., substituted (ethynyl) (vinyl) carbenium ions), light-absorbing in the near-infrared (up to 814nm in CH 2 Cl 2 ), have been synthesized by treatment of 1,3,5-trisubstituted 1-penten-4-yn-3-ols with acids. The light absorption behaviour of the bis(p-dimethylaminophenylethynyl)phenyl carbenium ion and related dyes in acidic medium is described.

Synthesis of pyrylium salts from trisubstituted 1,4-pentadiyn-3-ols with HClO4

Abstract The synthesis of 2,4,6-trisubstituted pyrylium salts from 1,3,5-trisubstituted 1,4-pentadiyn-3-ols with HClO 4 is reported for the first time.

Carotenoid synthesis with 4-(t-butylthio)-3-buten-2-one. A new synthesis of isorenieratene

Abstract Isorenieratene has been efficiently synthesized using 4-( t -butylthio)-3-buten-2-one as chain lengthening agent.

Fluorescence spectra characteristics of α,ω-Di-1- and 9-anthrylpoly-ynes

Abstract It has been found that the longest-wavelength of the absorption maxima (λ L ) in the electronic spectra of both the α,ω-diarylpoly-yne and polyene series varies linearly with the x th power of the number (n) of multiple bonds [λ L ∝ n x , the value of x changes with both the structure of the terminal groups and the position of substitution of the unsaturated chain, e.g. x = 2 for α,ω-Di-1-and 9-anthrylpoly-ynes( 1 n ,and 2 m n = 1–6)]. The results are different from the formerly accepted regularity (λ L 2 ∝ n ). The paper describes the fluorescence spectra characteristics of a series of 1 n and 2 n . The results of this investigation shows that, as in the case of the absorption spectra, both the excitation maxima ( λ ex ) and the emission maxima (λ em )in the fluorescence spectra of 1 n and 2 n have a linear relationship with n 2 (λ ex ∝ n 2 and λ em ∝ n 2 , respectively).

Synthesis and properties of 5-substituted 2-thiobarbituric acid dyes

Abstract The systematic synthesis of 5-substituted 2-thiobarbituric acid dyes (5-p-methoxy- and 5-p-dimethylamino-benzylidene-, cinnamylidene-, and phenylpentadienylidene-1, 3-disubstituted 2-thiobarbituric acids) is described and their absorption characteristics are reported.

New dye systems containing a cc bond

Abstract Preparation of the acetylenic analogues of triphenylmethane dyes (triphenyl-methane dye ethynylogues. TPMDE) and studies on their colour and constitution are described. Derivatives of pyrylium dyes and merocyanine dyes have been obtained in the preparative studies of TPMDE. The absorption and emission spectral properties of bis(phenylethynyl) benzenes and the related anthracene derivatives are summarized, together with some donor-acceptor tolan derivatives; for the preparation of these, a novel one-stage conversion of the CC bond to the CC acetylenic bond was found to be useful.