From the aerial parts of Solanum dulcamara, two spirostanol glycosides (1 and 2) and two new spirosolane glycosides (3 and 4) were isolated and their chemical structures were characterized as tigogenin 3-O-β-solatrioside, degalactotigonin, soladulcidine 3-O-β-chacotrioside (named soladulcine A), and soladulcidine 3-O-β-lycotetraoside (named soladulcine B), respectively.

View full abstract

A new spirostanol saponin and two new furostanol saponins were isolated from the fresh bulbs of Allium giganteum together with several known saponins. The structures of the new compounds were determined on the basis of spectroscopic data, the products formed on hydrolysis and by comparing their properties with those of known compounds. The isolated saponins and their derivatives were evaluated for inhibitory activity by examining their action on cAMP phosphodiesterase as a primary screening test to identify new medicinal agents.

View full abstract

Cerpegin (1), a new pyridone alkaloid, was synthesized starting from the Michael reaction of phenylthioacetonitrile (2) and 2-methoxycarbonyl-4, 4-dimethyl-2-buten-4-olide (3) in five steps. Catalytic hydrogenation of a nitrile group in the presence of a conjugated carbon-carbon double bond was performed by addition of 1 eq of conc. HCl.

View full abstract

A synthetic study on a series of benzimidazole derivatives including cycloalka[b]pyridine moiety has been carried out. Among these compounds synthesized, a novel antipeptic agent with 6, 7, 8, 9-tetrahydro-5H-cyclohepta[b]pyridine moiety (TY-11345) was found to be superior to omeprazole in (H⁺+K⁺)-ATPase inhibitory activity and antisecretory potencies.

View full abstract

Oxidative lactonization of 2-carboxystilbene mediated by CuCl₂ proceeded regiospecifically to give the five-membered lactone. By utilizing this lactonization as a key reaction, chemical transformation from dihydroisocoumarine into benzylidenephthalide was accomplished, and it was applied to structural elucidation of two new phthalide, hydramacrophyllols A and B.

View full abstract

We investigated the effects of bases, resins and S-protecting groups on the extent of racemization at the C-terminal cysteine during Fmoc-based(Fmoc=fluoren-9-yl-methoxy-carbonyl) solid phase peptide synthesis. The use of 2-chlorotrityl resin was most effective in suppressing the racemization caused by the base treatment for Fmoc-cleavage. Somatostatin was successfully synthesized with practically no racemization using 2-chlorotrityl resin by Fmoc-chemistry.

View full abstract

When a physical mixture of naphthalene and amorphized 2, 6-di-O-methyl-β-cyclodextrin was heated in a sealed container, a meta-stable complex was crystallized under a mild condition of heating, which showed excimer fluorescence emission of naphthalene. On the other hand, heating of the mixture at high temperature caused the crystallization of stable inclusion complex which showed monomer fluorescence emission.

View full abstract

The hairy roots of Trichosanthes kirilowii MAX. var. japonica KITAM. were induced by Agrobacterium rhizogenes (ATCC 15834) on sterile shoots. The axenic culture of hairy roots proliferated 30 to 60-fold based on the initial fresh weight after three weeks of culture in Murashige & Skoog liquid media. Bryonolic acid as the main triterpenoid was isolated in a high yield, together with chondrillasterol from the hairy roots of this plant. Bryonolic acid showed strong inhibition of the growth of B-16 melanoma cells.

View full abstract

Collagen-induced arthritis(CIA) was found to be useful as an animal model to investigate the mechanism by which rheumatoid arthritis is developed. We therefore studied variations of T and B lymphocytes in peripheral blood and bone marrow in order to ascertain the importance of T and B lymphocytes in the development of CIA. T lymphocyte, which is considered to be associated with the onset and deterioration of CIA, was not changed during the course of CIA, whereas B lymphocyte, which produces anti-type II collagen andtibody regarded as an indispensable factor in CIA induction, was significantly decreased in peripheral blood and bone marrow at 10 days after the 2nd immunization when arthritis was able to be detected. In bone marrow, although two cell populations of Ly5/B220-positive cells were detected, only the cell population with lower fluorescence intensity was decreased transiently. These results suggest that B lymphocyte in both bone marrow and peripheral blood is intimately involved in the course of CIA.

View full abstract

Three new labile monoterpenes named paeonisothujone, deoxypaeonisuffrone, and isopaeonisuffral were isolated from Chinese Moutan Cortex, the root cortex of Paeonia suffruticosa ANDREWS. The absolute stereostructures of paeonisothujone, deoxypaeonisuffrone, and isopaeonisuffral were elucidated on the basis of chemical and physicochemical evidence which included the application of the modified Mosher's method. Paeonisothujone is the first natural example of ortho-menthane type monoterpene having a cyclopropane ring.

View full abstract

Reaction of 2, 3-dioxo-2, 3-dihydro-4H-1, 4-oxazines 2a-e with dimethylsulfoxonium methylide introduced an exo-methylene group with concomitant ring contraction to give 4, 5-dioxo-2, 3, 4, 5-tetrahydrooxazoles 3a-e in moderate yields. Mechanism of this unusual reaction was discussed.

View full abstract

New type inhibitors of ethanol absorption, camelliasaponins B₁, B₂, C₁ and C₂, were isolated from the seeds of Camellia japonica L. The structures of camelliasaponins were elucidated on the basis of chemical and physicochemical evidence. The inhibitory effect of camelliasaponins and related saponins on ethanol absorption have been examined, and it was found that the triterpene oligoglycoside structure having an acyl group was essential to exerting the activity.

View full abstract

The whole process for the substitution of C-H bond in methane with fluorine by molecular fluorine was analyzed at HF/6-311++** level with IRC caluculation. Theoretical information including the transition state of this reaction was obtained in regard to electrophilic nature and retention of configuration.

View full abstract

Sterically constrained and highly congested N-acetyl-DMAOx (1a) serves well as a useful chiral acetyl enolate equivalent which permits a diastereoselective and direct approach to 'acetate' aldols (2) including statine derivative.

View full abstract

Achromobacter sp. lipase regioselectively acylated the hydroxyl group on sn-1 carbon among the two primary hydroxyl groups of 3-O-β-D-galactopyranosyl-sn-glycerol.

View full abstract

In this paper, we report chemical structures of five compounds including four novel polyhydroxylated cardiac steroids in the eggs of a toad, Bufo marinus. These cardiac steroids were purified by high-performance liquid chromatography, and their structrues were determined to be 11α, 19-dihydroxytelocinobufagin (I), 11α-hydroxytelocinobufagin (II), 11α, 19-dihydroxymarinobufagin (III), 11α-hydroxymarinobufagin (IV) and 19-hydroxytelocinobufagin (V) on the basis of spectral data of nuclear magnetic resonance and mass spectroscopy. All the five compounds showed biological activity, as tested by inhibition of Na⁺, K⁺-ATPase activity and of [³H]ouabain binding to the receptor on Na⁺, K⁺-ATPase. This is the first finding of bufadienolides as cardiac steroids in animal eggs.

View full abstract

Stereoselective synthesis of 7E, 9E- and 7E, 9Z-β-ionylideneacetaldehydes was accomplished from the β-ionone tricarbonyl iron complex, and the latter was converted to 9Z-retinoic acid.

View full abstract