Haruo Kitahara

LEWIS ACID CATALYZED ALLYLSTANNYLATION OF UNACTIVATED ALKYNES

Abstract The addition of allyltributylstannane 2 to unactivated aromatic alkynes 1 in the presence of catalytic amounts of ZrCl 4 or EtAlCl 2 produced the stannylated 1,4-dienes 3 with very high regio- and stereoselectivities in good to high yields. The exclusive trans manner of addition was confirmed by 1 H NMR analysis of crude reaction mixtures. On the other hand, the stereochemistries of addition products produced from the reactions using aliphatic acetylenes depended on the reaction conditions and the Lewis acid type. The mechanisms for the ZrCl 4 and EtAlCl 2 catalyzed allylstannylation of alkynes are proposed.

Opposite Effects of Two Resveratrol (trans-3,5,4′-Trihydroxystilbene) Tetramers, Vitisin A and Hopeaphenol, on Apoptosis of Myocytes Isolated from Adult Rat Heart

It has been reported that resveratrol (trans-3,5,4′-trihydroxystilbene) from Vitis plants has various cardioprotective effects. Vitis plants also include various resveratrol tetramers. The aim of our study is to clarify the pharmacological properties of resveratrol tetramers. We isolated two resveratrol tetramers as major products of Vitis plants. One is vitisin A, a complex of two resveratrol dimers, (+)-ϵ-viniferin and ampelopsin B, and the other is hopeaphenol, composed of 2 mol ampelopsin B. Vitisin A (30–300 nM) unexpectedly dose-dependently facilitated swelling and depolarization of mitochondria and cytochrome c release from mitochondria, which are indices of cardiomyocyte apoptosis. Furthermore, vitisin A induced apoptosis in the primary culture of adult rat ventricular myocytes. On the other hand, hopeaphenol (1–10 μM) dose-dependently inhibited Ca2+ (30 μM)-induced mitochondrial depolarization and cytochrome c release from mitochondria but had not affected mitochondrial swelling. Moreover, hopeaphenol inhibited vitisin A-induced apoptosis. In structural and functional studies, we further confirmed that vitisin B, one of the resveratrol tetramers having (+)-ϵ-viniferin unit, induces mitochondrial swelling and cytochrome c release from mitochondria like vitisin A and that vitisifuran A, one of the resveratrol tetramers having the ampelopsin B unit, inhibits Ca2+-induced cytochrome c release from mitochondria like hopeaphenol. These results show that resveratrol tetramers have at least two opposite effects on cardiomyocytes; the one having the (+)-ϵ-viniferin unit induces cardiomyocyte apoptosis, and the other having ampelopsin B but not (+)-ϵ-viniferin unit inhibits it.

1,2-Asymmetric Induction in the Conjugate Addition of Organocopper Reagents to γ-Aryl α,β-Unsaturated Carbonyl Derivatives

Abstract The diastereoselectivity in the conjugate addition of organocopper reagents to γ-aryl α,β-unsaturated carbonyl derivatives 8–14 was investigated. The syn -diastereoselectivity was obtained irrespective of the reagents type in the addition of 8, while the anti -diastereoselectivity was obtained in the addition of 10–14 with RCu and RCu(CN)Li (R=Me and Bu) and the syn -selectivity was produced in the addition of 10–14 with R 2 CuLi and R 2 Cu(CN)Li 2 . The reagent controlled and substrate dependent diastereoselectivity are explained by two different reaction pathways: either π-complex formation or ordinary nucleophilic addition. Reduction potentials of the Michael acceptors and electron donating ability of organocopper reagents control the reaction pathway.

8-Methyltryptanthrin-induced differentiation of P19CL6 embryonal carcinoma cells into spontaneously beating cardiomyocyte-like cells.

Enhancement of cardiac differentiation is critical to stem cell transplantation therapy for severe ischemic heart disease. The aim of this study was to investigate whether several derivatives of tryptanthrin (1), extracted from the medicinal plant Polygonum tinctorium, induce the differentiation of P19CL6 mouse embryonal carcinoma cells into beating cardiomyocyte-like cells. P19CL6 cells were cultured in α-MEM supplemented with 10% FBS including a test compound or vehicle. Drug-induced differentiation was assessed by measuring the number of beating and nonbeating aggregates and the area of beating aggregates, and the expression of genes involved in cardiac differentiation was evaluated by real-time PCR. A 1 μM concentration of 8-methyltryptanthrin (2) induced the differentiation of P19CL6 cells into cardiomyocyte-like cells to a significantly greater degree than 1% dimethyl sulfoxide (DMSO), a conventional differentiation inducer of P19CL6 cells. Furthermore, 2 strongly increased both the number and the area of spontaneously beating aggregates in comparison with DMSO. Two distinct genes of the calcium channel family, Cav1.2 and Cav3.1, underlying cardiac automaticity were significantly expressed in the presence of 2. Gap junction genes GJA1 and GJA5 contributing to the synchronized contraction of the myocardium were also induced significantly by 2. These results suggest that 2 successfully differentiated P19CL6 cells into spontaneously beating cardiomyocyte-like cells by activating the gene expression of pacemaker channels and gap junctions.

Intramolecular exciplex formation and complexing behavior of 1-(2-naphthalenecarboxy)-n-(p-substituted benzenecarboxy)oxaalkanes as fluorescent chemosensors for calcium and barium ions

Abstract 1-(2-Naphthalenecarboxy)- n -( p -substituted benzenecarboxy)oxaalkanes (2NP n X, X=H, Cl, CF 3 , CN; n =5, 6) as fluorescent sensors by exciplex emission for metal ions were synthesized. We investigated the relationship between the substitution effects and the metal ion recognition. Before the metal salts were added, the substitution effect was found. The fluorescence quantum yields ( Φ f ) decrease as the electronegativity of the p -substituent of the acceptor benzoate increases. 2NP n CN ( n =5, 6) with the most negative free energy of electron transfer (Δ G ET ) showed the most efficient quenching and exciplex emission. When Li + , Na + , K + and Mg 2+ were added to the acetonitrile solution of 2NP n X (X=H, Cl, CF 3 , CN; n =5, 6), the shape and intensity of the fluorescence spectra did not change. However, the spectra of all the 2NP n Xs significantly changed with the addition of Ca 2+ and Ba 2+ . Especially, due to the large fluorescent enhancement factor of 2NP n CN ( n =5, 6) for Ca 2+ , they are well-suited for use as a fluorescent chemosensor for Ca 2+ .

Substrate Specificities of Several Prenyl Chain Elongating Enzymes with Respect to 4-Methyl-4-pentenyl Diphosphate

In order to develop synthetic methods for biologically active homoallylic terpene sulfates, we examined the applicability and substrate specificities of several prenyl chain elongating enzymes with respect to 4-methyl-4-pentenyl diphosphate (homoIPP). The reaction of dimethylallyl diphosphate with homoIPP by use of Bacillus stearothermophilus (all-trans)-farnesyl diphosphate synthase resulted in efficient yields of cis-(yield: 45.9%) and trans-4,8-dimethylnona-3,7-dien-1-ol (homoGOH, 25.5%), which has a carbon skeleton of 4,8-dimethylnona-3-en-1-sulfate, an antiproliferative compound from a marine organism (Aiello, A. et al., Tetrahedron, 53, 11489–11492 (1997)). The homoIPP was found to be also active as a homoallylic substrate in place of isopentenyl diphosphate for Sulfolobus acidocaldarius geranylgeranyl diphosphate synthase to give diphosphate of cis- and trans-4,8,12-trimethyltrideca-3,7,11-trien-1-ol, for Micrococcus luteus B-P 26 hexaprenyl diphosphate synthase to give cis- and trans-4,8,12,16-tetramethylheptadeca-3,7,11,15-tetraen-1-ol (homoGGOH), and for Micrococcus luteus B-P 26 undecaprenyl diphosphate synthase to give cis-homoGGOH exclusively.

Br-DIF-1 accelerates dimethyl sulphoxide-induced differentiation of P19CL6 embryonic carcinoma cells into cardiomyocytes

BACKGROUND AND PURPOSE Stem cell transplantation therapy is a promising option for treatment of severe ischaemic heart disease. Dimethyl sulphoxide (DMSO) differentiates P19CL6 embryonic carcinoma cells into cardiomyocyte‐like cells, but with low differentiation capacity. To improve the degree of this differentiation, we have assessed several derivatives of the differentiation‐inducing factor‐1 (DIF‐1), originally found in the cellular slime mould Dictyostelium discoideum, on P19CL6 cells.

Purification and identification of the promoter of sediment formation from raw soy sauce by heating

Abstract Soy sauce contains promoters of sediment formation at 60°C. These promoters were extracted with 1-butanol from raw soy sauce, followed by acetonitrile extraction. The acetonitrile-soluble fraction was used for further separation of the promoter of sediment formation, as the specific activity of the acetonitrile-soluble fraction was higher than that of the insoluble fraction. The promoter of sediment formation could be separated as a single peak from the main low-molecular weight peak on a Sephadex G-10 column by means of HPLC on a LiChrospher (RP-18) column. The active fraction for sediment forming-activity separated by three columns, namely, a LiChrospher (RP-18) column, an Alltech 700CH carbohydrate column and a Shodex OHpak Q-801 column, was observed as a single peak. 0.08 g of promoter was obtained from 1l of raw soy sauce. The 13C, 1H NMR and 1H-1H COSY spectral data identified the purified promoter as l -glutamic acid 5-n-butyl ester. l -Glutamic acid 5-n-butyl ester was synthesized and identified as a promoter by HPLC and 1H NMR analysis. In addition, the existence of l -glutamic acid 5-n-butyl ester in raw soy sauce was confirmed by HPLC analysis of the extract without 1-butanol extraction from raw soy sauce.

Isomers and homologues of L-glutamic acid 5-n-butyl ester as promoters of sediment formation in raw soy sauce.

Soy sauce was found to contain promoters of sediment formation at 60 degrees C, one of which has previously been identified as L-glutamic acid 5-n-butyl ester. Isomers and homologues of L-glutamic acid 5-n-butyl ester (n-propyl, isopropyl, n-butyl, isobutyl, and sec-butyl esters of L-glutamic acid) were synthesized using 80% (w/w) sulfuric acid as a catalyst and identified by 1H-NMR and the ninhydrin test. The yields of L-glutamic acid 5-n-propyl, isopropyl, n-butyl, isobutyl, and sec-butyl esters from 10 g L-glutamic acid were 25, 101, 72, 130, and 134 micromol, respectively. For maximum sediment formation in 1 ml soy sauce, 1.2, 8.6, 22.0, 22.0, and 26.5 micromol/ml of n-butyl, n-propyl, isobutyl, sec-butyl, and isopropyl esters were respectively required. Sediment-forming activity was not observed with L-glutamic acid and L-glutamic acid 5-methyl, ethyl and tert-butyl esters.

Photophysical Properties of the 2-Hydroxytryptanthrin and Its Sodium Salt as Near-infrared Dyes for Fluorescent Imaging

2-Hydroxytryptanthrin (T2OH) and its sodium salt (sodium tryptanthrin-2-olate, T2ONa) were synthesized as near-infrared (NIR) dyes for fluorescent imaging. The absorption maxima (λ(a,max)) of T2OH under a pH range from 1.3 to 7.2 and from 8.5 to 10.6 were ca. 410 nm and ca. 495 nm, respectively. Moreover, the fluorescence maxima (λ(f,max)) were ca. 660 nm regardless of the pH range. T2ONa was water soluble and the λf,max were ca. 660 nm in both aprotic and protic solvents.