Tomihisa Ohta

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.

Structure-activity relationship of ericaceous. Toxins on acute toxicity in mice

Abstract The acute toxicity of 36 samples of ericaceous toxins and their congeners has been determined using mice. Those whose LD50 values are low (

DIASTEREOSPECIFIC SYNTHESIS OF (-)-STATINE

Abstract Reductive deoxygenation at quarternary α-carbon of α-hydroxy lactam was found to proceed under mild condition. Making an advantage of this procedure, (−)-statine was synthesized from L-malic acid in a diastereospecific manner.

EFFECTS OF L-DOPA AND BROMOCRIPTINE ON HALOPERIDOL-INDUCED MOTOR DEFICITS IN MICE

L-3,4-Dihydroxyphenylalanine (L-DOPA), the precursor of dopamine, and bromocriptine, a dopamine D2 receptor agonist, were investigated in haloperidol-induced motor impairments in mice using both catalepsy and pole tests. In catalepsy test, subcutaneous treatment with haloperidol (0.125, 0.25 and 0.5 mg/kg) caused a cataleptic effect in mice in a dose-dependent manner. This cataleptic effect was evident upto 7 hr after haloperidol treatment. In pole test, haloperidol (0.125, 0.25 and 0.5 mg/kg) produced the prolongation of Tturn and TLA as a marker of bradykinesia in mice and the prolongation lasted at least 7 hr after haloperidol treatment. Intraperitoneal co-pretreatment with L-DOPA (400 mg/kg) + carbidopa (10 mg/kg) in mice decreased the catalepsy induced by haloperidol at a dose of 0.125 mg/kg, while co-pretreatment with L-DOPA (200 and 400 mg/kg) + carbidopa (10 mg/kg) dose-dependently decreased the haloperidol (0.125 mg/kg)-induced bradykinesia. The effect of LDOPA + carbidopa in pole test was more pronounced than that in catalepsy test. Intraperitoneal pretreatment with bromocriptine (2 and 4 mg/kg) in mice reduced the catalepsy and bradykinesia produced by haloperidol at a dose of 0.125 mg/kg. The effect of bromocriptine in pole test was relatively similar to that in catalepsy test. Also, co-pretreatment with LDOPA (400 mg/kg) + carbidopa (10 mg/kg) and pretreatment with bromocriptine (2 and 4 mg/kg) significantly decreased the catalepsy induced by haloperidol at a higher dose of 0.5 mg/kg. These results indicate that co-administration with L-DOPA + carbidopa and single treatment with bromocriptine can decrease haloperidol-induced catalepsy and bradykinesia in mice. Furthermore, our study suggests that pole test as well as catalepsy test is of value in the screening of drugs against neuroleptic-induced motor deficits.