Shigeo Nozoe

Ascididemin, a novel pentacyclic aromatic alkaloid with potent antileukemic activity from the Okinawan tunicate Didemnum sp.

Abstract A novel pentacyclic aromatic alkaloid, ascididemin (1), with potent antineoplastic activity has been isolated from the Okinawan tunicate Didemnum sp. Its structure was elucidated on the basis of spectroscopic data.

Ageliferins, potent actomyosin Atpase activators from the Okinawan marine sponge Agelas sp

Abstract Three bromopyrrole alkaloids, ageliferin (1), bromoageliferin (2), and dibromoageliferin (3), have been isolated as potent actomyosin ATPase activators from the Okinawan marine sponge Agelas sp. and the structures elucidated on the basis of spectral data, especially two dimensional NMR spectra.

Theonelladins A ∼ D, novel antineoplastic pyridine alkaloids from the Okinawan marine sponge Theonella swinhoei

Abstract Novel pyridine alkaloids, theonelladins A ∼ D, with potent antileukemic activity have been isolated from the Okinawan marine sponge Theonella swinhoei and the structures elucidated on the basis of spectroscopic data.

Pharmacological properties of α-mangostin, a novel histamine H1 receptor antagonist

Abstract In the isolated rabbit thoracic aorta and guinea-pig trachea, α-mangostin inhibited histamine-induced contractions in a concentration-dependent manner in the presence or absence of cimetidine, a histamine H 2 receptor antagonist. But KCl-, phenylephrine- or carbachol-induced contractions were not affected by α-mangostin. The concentration-contractile response curve for histamine was shifted to the right in a parallel manner by α-mangostin. In the presence of chlorpheniramine, a histamine H 1 receptor antagonist, α-mangostin did not affect the relaxation of the rabbit aorta induced by histamine. In the guinea-pig trachea, α-mangostin had no effect on the relaxation induced by dimaprit, a histamine H 2 receptor agonist. α-Mangostin caused a concentration-dependent inhibition of the binding of [ 3 H]mepyramine, a specific histamine H 1 receptor antagonist to rat aortic smooth muscle cells. Kinetic analysis of [ 3 H]mepyramine binding indicated the competitive inhibition by α-mangostin. These results suggest that α-mangostin is a novel competitive histamine H 1 receptor antagonist in smooth muscle cells.

Mangostanol, a prenyl xanthone from Garcinia mangostana

Abstract During studies for identification of biologically active components from natural sources, a new polyoxygenated xanthone mangostanol was isolated from the fruit hull of Garcinia mangostana , along with known xanthones, α-mangostin, γ-mangostin, gartanin, 8-deoxygartnin, 5,9-dihydroxy-2,2-dimethyl-8-methoxy-7-(3-methylbut-2-enyl)-2 H ,6 H -pyrano[3,2- b ]xanthen-6-one, garcinone E and 2-(γ,γ-dimethylallyl)-1,7-dihydroxy-3-methoxyxanthone and epicatechin. Spectroscopic analysis mainly by 1D and 2D NMR spectroscopy, established the structure of mangostanol {3,5,9-trihydroxy-2,2-dimethyl-8-methoxy-7-(3-methylbut-2-enyl)-2 H ,6 H -3,4-dihydropyrano[3,2- b ]xanthen-6-one} Mangostanol, and α- and γ-mangostin show moderate inhibitory effects on cAMP phosphodiesterase.

Stereoselective hydroxylation of N-carbamoyl-L-pyroglutamate. Synthesis of (−)-bulgecinine

Abstract Regio- and diastereoselective hydroxylation of the monoenolate derived from N- t -butoxycarbonyl-L-pyroglutamate ( 1 ) afforded the optically pure (4 R )-hydroxypyroglutamate ( 2a ) from which (−)-bulgecinine ( 3 ) was synthesized.

Hyrtiosins A and B, new indole alkaloids from the Okinawan marine sponge Hyrtios erecta

Abstract Two new indole alkaloids, hyrtiosins A (2) and B (3), together with known 5-hydroxyindole-3-aldehyde (1) have been isolated from the Okinawan marine sponge Hyrtios erecta and their structures elucidated on the basis of the spectroscopic data.

Avenic acid, a new amino acid possessing an iron chelating activity

Abstract A new amino acid derivative possessing an iron chelating activity was isolated from root washings of water cultured Avena sativa under iron deficient conditions. The structure of this compound, avenic acid A has been determined as 2(S),3′(S),3″(S)-N-[3-(3-hydroxy-3-carboxypropylamino)-3-carboxypropyl]-homoserine (1) on the basis of chemical and spectroscopic evidence.

Kukoamine B, a spermine alkaloid from Lycium chinense

Abstract A new spermine alkaloid, kukoamine B, was isolated from the root bark of Lycium chinense and its structure was characterized by a combination of spectroscopic analyses and chemical degradation. Kukoamine B consists of two dihydrocaffeoyl moieties and a spermine unit.

Selective inhibition of T-cell-dependent immune responses by bisbenzylisoquinoline alkaloids in vivo

The bisbenzylisoquinoline (BBI) alkaloids, chondocurine, tetrandrine, isotetrandrine and cepharanthine, were tested for immunosuppressive activity in mice. A plaque-forming cell (PFC) response to a T-cell-dependent antigen, sheep red blood cell, was significantly suppressed by a 7 day treatment of chondocurine or tetrandrine at 1 mg/kg/day and of isotetrandrine at 50 mg/kg/day, but not suppressed by cepharanthine treatment. The suppressive effect of chondocurine was greater when it was given after immunization rather than before or concurrently. However, it did not affect the PFC response to a T-cell-independent antigen, lipopolysaccharide. A delayed-type hypersensitivity was also suppressed by chondocurine treatment. There was no significant change in lymphocyte number and proportion of T-cell subsets in the BBI alkaloid-treated mice. These data suggest that there is selective inhibition by chondocurine and tetrandrine of the T-cell-dependent immune reactions.