Teruo Kurihara

Cancer prevention and therapy with kiwifruit in Chinese folklore medicine: A study of kiwifruit extracts

Kiwi gold fruits were extracted successively with hexane, acetone, methanol and 70% methanol, and further fractionated by silica gel and ODS column chromatographies for the assays of various biological activities. Five fractions H1, H2 (hexane extract), Al, A2 (acetone extract) and M2 (methanol extract) showed selective cytotoxic activity against human oral tumor cell lines, which was more sensitive than human gingival fibroblasts. More hydrophilic fractions [70M3, 70M4, 70M5] of 70% methanol extract displayed higher anti-HIV activity, radical generation and O2- scavenging activity. The antibacterial activity of 70% methanol extracts [70M0, 70M1, 70M2, 70M3, 70M4] was generally lower than that of more lipophilic fractions (hexane, acetone, methanol extracts), although each fraction did not show any specific antimicrobial action. All fractions were inactive against Helicobacter pylori. These results demonstrate that gold kiwifruit extracts contain valuable, various bioactive materials, which can be separated with each other.

First total synthesis of pyrrolam A

First synthesis of pyrrolam A (1), a pyrrolizidine alkaloid from Streptomyces olivaceus, was accomplished. The SmI2-mediated intramolecular coupling reaction between a bromoalkyl and ynamide group gave solely a cyclized product, which was converted to pyrrolam A (1) efficiently.

Factors that Affect the Type of Cell Death Induced by Chemicals

Surveying about 1000 compounds, we found that several low molecular weight α,β-unsaturated ketones induced non-apoptotic cell death characterized by the formation of autophagosomes, occasionally accompanied by mitochondrial shrinkage. The cytotoxic activity of these compounds was significantly reduced by the addition of N-acetyl-L-cysteine, suggesting their interaction with SH groups of intracellular targeted molecules (the so-called “non-sterically hindered Michael acceptor”). This suggests that the nature of the chemical structure as well as the type of target cells is another factor that determines the type of cell death induced by chemicals. Addendum to: Tumor-Specificity and Type of Cell Death Induced by Trihaloacetylazulenes in Human Tumor Cell Lines T. Sekine, J. Takahashi, M. Nishishiro, A. Arai, H. Wakabayashi, T. Kurihara, M. Kobayashi, K. Hashimoto, H. Kikuchi, T. Katayama, Y. Kanda, S. Kunii, N. Motohashi and H. Sakagami Anticancer Res 2007; 27:133-44

Synthesis and biological activity of N-acylphenothiazines

Previous studies have demonstrated the relationship between radical intensity and cytotoxic activity in water-soluble compounds. This relationship was investigated in lipophilic compounds. Several N-acylphenothiazines showed higher cytotoxic activity against human leukemic and squamous carcinoma cell lines than phenothiazine, the parent compound. Electron spin resonance (ESR) spectroscopy showed that these active compounds produced much lower amounts of radicals than phenothiazine. Several compounds failed to inhibit the cytopathic effects of human immunodeficiency virus (HIV) infection in MT-4 cells. It suggested that the radical-mediated-mechanisms has not involved in the induction of cytotoxic activity by lipophilic compounds, such as N-acylphenothiazines.

First total synthesis of (±)-oxerine

Abstract Total synthesis of (±)-oxerine (1), a monoterpene alkaloid, starting from 3-bromopyridine (7) is described. The key reaction in this sequence is the samarium iodide (SmI2)-mediated intramolecular cyclization of γ-ethynyl bromide (4).

Unexpected product from the Dakin-West reaction of N-acylprolines using trifluoroacetic anhydride: A novel access to 5-trifluoromethyloxazoles

Abstract The base-catalyzed reaction of N-acylprolines with trifluoroacetic anhydride proceeds through mesoionic 1,3-oxazolium-5-olates followed by the pyrrolidine ring cleavage to afford the 5-trifluoromethyloxazoles in good yields.

Synthesis of 1,2-azulenequinone derivatives by bromine-oxidation

Treatment of 2-hydroxyazulene (la) with 3 equiv. of C 5 H 5 N·HBr 3 in aqueous THF-AcOH at 0 °C for 1 h afforded l,l,3-tribromoazulene-2-one (5a). 3-Bromo-l,2-azulenequinone (2a) was obtained by the hydrolysis of 5a in the presence of Ag 2 O. Annulated compound 6 was readily obtained by the reaction of 2a with o-phenylenediamine.

A convenient synthesis of α-trifluoremethylated and α-perfluoroalkylated acyloins from α-hydroxy acids

Abstract A novel transformation of α-hydroxy acids to α-trifluoremethylated and α-perfluoroalkylated acyloins was efficiently realized by utilizing trifluoroacetic or perfluoroalkylcarboxylic anhydrides in the presence of pyridine, in which probable intermediates were meso-ionic 1,3-dioxolium-4-olates.

Syntheses of a naturally occurring hydroxamic acid and its analogues

A naturally occuring cyclic hydroxamic acid, isolated from Pseudomonas species, and its analogues were synthesized via six steps starting from 2-hydroxy-3-methoxy-pyridine. The antimicrobial activity of the synthesized compounds is described.

Dynamics and mechanistic features in the photocatalyzed oxidation of disulfonated anionic surfactants on the surface of UV-irradiated titania nanoparticlesElectronic supplementary information (ESI) available: calculated frontier electron densities and point charges of selected atoms in the DOBS derivatives and in the DBS system taken for comparison. See http://www.rsc.org/suppdata/nj/b4/b402583k/

The photocatalyzed transformation of the anionic 4-dodecyl-1,1′-oxybisbenzenedisulfonate (DOBS) surfactant and its derivatives was carried out in aqueous TiO2 dispersions under UV and aerated illumination conditions to examine the dynamics and the mechanistic features of the degradative processes. Spectroscopic and other methodologies were used to probe the break-up of the aromatic ring, the mineralization of the surfactant(s) to carbon dioxide, decay of total organic carbon (TOC) remaining in solution, formation of sulfate ions, and identification of oxidation intermediates (e.g., acetic acid, formic acid and acetaldehyde) by NMR spectroscopy. Adsorption of DOBS, in particular, and the other anionic surfactant derivatives in general, on the TiO2 particle surface was inferred from the calculated point charges. Frontier electron densities of all atoms ascertained the positions of ˙OH radical attack on the DOBS molecular skeleton. A model for the initial adsorption behavior of DOBS through electrostatic forces between the anionic surfactant(s) and the cationic TiO2 particle surface is proposed, aided by evidence from ζ-potential measurements. It is deduced that ˙OH radicals attack preferentially the carbon atoms bonded to the sulfonate groups on the DOBS aromatic rings, followed by further attack on the remaining carbon atoms of the aromatic rings first and then more slowly on the carbon atoms of the hydrophobic alkyl chain.