Two cytotoxic squalene-derived polyethers from the Japanese red alga Chondria armata.

The red alga Chondria armata is known to produce and contain a rich diversity of secondary metabolites, such as domoic acid-related alkaloids and triterpene polyethers. Our investigation on red alga C. armata from Kagoshima coast, Japan, resulted in the isolation of two new triterpene polyethers, bandokorols A (1) and B (2). The structures of these compounds were determined based on spectroscopic data such as infrared (FTIR), 1H-NMR, APT, 1H-1H-COSY, HSQC, HMBC, NOESY and FAB mass spectrometry (HRFABMS). The anticancer potentials of these compounds were tested against adult T-cell leukaemia (ATL), S1T cells and their IC50 values are reported here.

Composition and Monthly Changes of the Volatile Constituents in the Sour Hetsuka-daidai Citrus Peel.

Sour citrus are prized for their flavor and fragrance. This work identified the components of the peel oil of Hetsuka-daidai (Citrus sp. hetsukadaidai), a special sour citrus that is native to the southern part of the Osumi peninsula, Kagoshima, Japan. These compounds were compared to those identified from the peels of six other major sour citrus: lime (Citrus latifolia), lemon (Citrus limon), Yuzu (Citrus junos), Kabusu (Citrus aurantium), Kabosu (Citrus sphaerocarpa), and Sudachi (Citrus sudachi). Peel oil contents were analyzed for the duration of four months during harvest season to investigate the differences in peel oil/fragrance during ripening. These results could facilitate the development of preferred flavor and scent profiles using local species.

Preparation of antimicrobial gold and silver nanoparticles from tea leaf extracts.

Gold and silver nanoparticles were prepared from the green tea and black tea extracts of the leaves of Camellia sinensis. The metal nanoparticle solutions were obtained by reacting HAuCl4 or AgNO3 aqueous solutions with aqueous NaHCO3 and tea leaf extracts, which were obtained from used tea leaves at low temperature, under ambient conditions. The nanoparticles were stable at room temperature and had a uniform particle size (Au: ∼10 nm, Ag: ∼30 nm). Nanoparticle-immobilized cotton cloths were then prepared, which displayed high antibacterial activity and a characteristic color, thereby showing potential application as antimicrobial pigments. This study provides a means of utilizing used tea leaves, which would otherwise be considered waste products.

Spontaneous Preparation of Highly Stable Gold Nanoparticle Stabilized with ω-Sulfonylated Alkylsulfanylaniline.

Preparation, characterization, and stability evaluation of gold nanoparticles stabilized by ω-sulfonylated alkylsulfanylaniline have been described. The particle solution was obtained by the spontaneous reaction of HAuCl4 and ω-sulfonylated alkylsulfanylaniline in boiling water. It showed a deep red color, owing to surface plasmon resonance of the resulting gold nanoparticles. The size and shape of the nanoparticles were pH-dependent, and pH 8 was found to be the most suitable condition to prepare stable nanoparticles with an average size of 11.2 ± 5.9 nm. The resulting particle solution was stable for a wide range of pH (3-13) and in phosphate-buffered saline (PBS) solution. The nanoparticles were storable as dried powder for at least two weeks, and were redispersible in water or PBS to give almost the same absorption spectra as the freshly prepared solution. Nanoparticle modification was achieved by simply adding thiol molecules to the particle solution.

Total Synthesis of the Claimed Structure of (±)-Hyptinin and Structural Revision of Natural Hyptinin.

A total synthesis of (±)-hyptinin was achieved via a convergent route using the key phosphonate, cyclic ketone, and aryl Grignard components. The 1H and 13C NMR spectra of natural hyptinin did not agree with those of the synthesized compound. In particular, there were considerable differences between the signals assigned to the protons and carbons surrounding the lactone carbonyl group for the natural and synthesized compounds. The NMR data strongly suggested that the naturally occurring compound, hyptinin, was a structural isomer of the synthesized compound. The structure of the natural compound was eventually established as (+)-ß-apopicropodophyllin, based on the synthesis results.

Silica gel-mediated organic reactions under organic solvent-free conditions.

Silica gel was found to be an excellent medium for some useful organic transformations under organic solvent-free conditions, such as (1) the Friedel-Crafts-type nitration of arenes using commercial aqueous 69% nitric acid alone at room temperature, (2) one-pot Wittig-type olefination of aldehydes with activated organic halides in the presence of tributyl- or triphenylphosphine and Hunig's base, and (3) the Morita-Baylis-Hillman reaction of aldehydes with methyl acrylate. After the reactions, the desired products were easily obtained in good to excellent yields through simple manipulation.

Ruthenium(salen)-catalyzed aerobic oxidative desymmetrization of meso-diols and its kinetics.

Chiral (nitrosyl)ruthenium(salen) complexes were found to be efficient catalysts for aerobic oxidative desymmetrization of meso-diols under photoirradiation to give optically active lactols. The scope of the applicability of this reaction ranges widely from acyclic diols to mono-cyclic diols, although fine ligand-tuning of the ruthenium(salen) complexes was required to attain high enantioselectivity (up to 93% ee). In particular, the nature of the apical ligand was found to affect not only enantioselectivity but also kinetics of the desymmetrization reaction. Spectroscopic analysis of the oxidation disclosed that irradiation of visible light is indispensable not only for dissociation of the nitrosyl ligand but also for single electron transfer from the alcohol-bound ruthenium ion to dioxygen.