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Biomedical subjects

Tomihisa Ohta

Publications and source records attributed to Tomihisa Ohta.

At least 19 recordsLinked to original sources
PubMed2005

Hexylitaconic acid: a new inhibitor of p53-HDM2 interaction isolated from a marine-derived fungus, Arthrinium sp.

A new inhibitor of p53-HDM2 interaction was isolated from a culture of marine-derived fungus, Arthrinium sp. The structure was identified to be (-)-hexylitaconic acid (1) by spectroscopic analysis. The inhibition of p53-HDM2 binding was tested by the ELISA method, and 1 inhibited the binding with an IC(50) value of 50 microg/mL. Although a number of synthetic inhibitors of p53-HDM2 interaction have been reported so far, 1 is the second inhibitor isolated from natural resources.

Ascomycota↗
PubMed2005

Isolation of CYP3A4 Inhibitors from the Black Cohosh (Cimicifuga racemosa).

Recent investigation on drug interaction has shown that some foods and herbal medicines increase the oral availability of a variety of CYP3A4 substrates, which is caused by the reduction of CYP3A4 in intestinal epithelium. During the course of our investigation on CYP3A4 interaction, we found that the commercially available dietary supplement made from black cohosh (Cimicifuga racemosa) showed CYP3A4 inhibition. Black cohosh has been used for the treatment of menopausal and post-menopausal symptoms as a dietary supplement. Bioassay-guided isolation from the supplement afforded six active principles, which were identified as cycloartanoid triterpene glycosides.

Journal Article↗
PubMed2005

Himeic acid A: a new ubiquitin-activating enzyme inhibitor isolated from a marine-derived fungus, Aspergillus sp.

A new ubiquitin-activating enzyme (E1) inhibitor, himeic acid A, was isolated from a culture of marine-derived fungus, Aspergillus sp. The structure was determined by spectroscopic analysis. The formation of an E1-ubiquitin (Ub) intermediate was 65% inhibited by himeic acid A at the concentration of 50 microM, while two new related compounds, himeic acids B and C, showed little inhibitory activity even at 100 microM.

Aspergillus↗
PubMed2005

The liquid culture filtrates of Paecilomyces tenuipes (Peck) Samson (=Isaria japonica Yasuda) and Paecilomyces cicadae (Miquel) Samson (=Isaria sinclairii (Berk.) Llond) regulate Th1 and Th2 cytokine response in murine Peyer's patch cells in vitro and ex vivo.

The effects of liquid culture filtrates of medicinal entomogenous fungi, Paecilomyces tenuipes (Peck) Samson (=Isaria japonica Yasuda or Isaria tenuipes) (PTCF) and Paecilomyces cicadae (Miquel) Samson (=Isaria sinclairii (Berk.) Llond) (PCCF), on cytokine productions in cultured Peyer's patches (PP) from C57BL/6J mice were investigated in vitro and ex vivo. In an in vitro experiment, PTCF (100 and 10 microg/ml) enhanced the production of T helper 1 (Th1) cytokines, interleukin (IL)-2 and interferon (IFN)-gamma, in cultured PP cells stimulated with 5 microg/ml concanavalin A (Con A) but did not influence on the production of T helper 2 (Th2) cytokines, IL-4 and IL-5. PTCF also enhanced the production of granulocyte macrophage colony-stimulating factor (GM-CSF) and IL-10 in the cultured PP cells. While, PCCF enhanced the production of IFN-gamma but did not alter the level of IL-2 in the PP cells. In an ex vivo experiment using PP cells removed from the mice after oral treatment of PTCF (10 and 100 mg/kg daily for 7 consecutive days), the production of IL-2 and IFN-gamma were increased in response to Con A. On the other hand, orally treated PCCF (10 mg/kg/day) suppressed IL-2 production but did not change the levels of IFN-gamma and IL-10 in the isolated PP cells. The flow cytometric analysis revealed that the population of CD3(+) cells in the PP cells slightly but significantly increased after oral administration of PCCF. Orally administered PTCF did not change the population of T (CD3(+)), B (CD19(+)), T cell subset (CD4(+)and CD8(+)) and Th1 (IFN-gamma(+)) and Th2 (IL-4(+)). From PTCF, the fraction rich in proteoglycans was separated as active fraction that stimulates Th1 immune response. These results indicate that the mode of action of PTCF and PCCF on mucosal immune response is different and this is contributed to their metabolites. Taken together, there is a possibility of PTCF and PCCF being therapeutic or preventive agents for immune diseases such as cancer, allergy and parasitic disease through activation of mucosal immune response.

Animals↗
PubMed2005

7-hydroxy-3-(4-hydroxybenzyl)chroman and broussonin b: neurotrophic compounds, isolated from Anemarrhena asphodeloides BUNGE, function as proteasome inhibitors.

The extract of Anemarrhenae Rhizoma (rhizomes of Anemarrhena asphodeloides BUNGE) showed neurotrophic activity toward rat pheochromocytoma (PC-12) cells. Bioassay-guided purification afforded four compounds, 2,6,4'-trihydroxy-4-methoxybenzophenone (1), 7-hydroxy-3-(4-hydroxybenzyl)chroman (2), broussonin B (3), and cis-hinokiresinol (4). Compounds 1-3 induced neurite outgrowth in PC-12 cells at concentration of 50 microg/ml, while 4 was less active. In addition, compounds 2-4 showed moderate inhibitory activities against a chymotrypsin-like activity of the proteasome.

Alkanes↗
PubMed2005

CYP3A4 inhibitors isolated from Licorice.

The extract of licorice (Glycyrrhiza uralensis FISHER, Leguminosae) showed CYP3A4 inhibitory activity with the IC50 value of 0.022 mg/ml. Bioassay-guided purification afforded nine compounds, 3-(p-hydroxyphenyl)propionic acid (1), isoliquiritigenin (2), (3R)-vestitol (3), licopyranocoumarin (4), 4-hydroxyguaiacol apioglucoside (5), liquiritin (6), liquiritigenin 7,4'-diglucoside (7), liquiritin apioside (8), and glucoliquiritin apioside (9). Among these compounds, 3, 7, and 5 showed potent CYP3A4 inhibitory activities with IC50 values of 3.6, 17, and 20 microM, respectively. Glycyrrhizin (10), a main constituent of licorice, however, was inactive for CYP3A4 inhibition.

Cytochrome P-450 CYP3A Inhibitors↗
PubMed2004

Aspermytin A: a new neurotrophic polyketide isolated from a marine-derived fungus of the genus Aspergillus.

A new polyketide, aspermytin A (1), was isolated from a cultured marine fungus, Aspergillus sp., which was separated from the mussel, Mytilus edulis. Its structure was elucidated on the basis of their spectral data, and the absolute configuration of 1 was determined by the CD spectrum. Aspermytin A induced neurite outgrowth in rat pheochromocytoma (PC-12) cells at concentration of 50 microM.

Animals↗
PubMed2004

Isolation of cytochrome P450 inhibitors from strawberry fruit, Fragaria ananassa.

A new glycoside, 2-beta-d-glucopyranosyloxy-4,6-dihydroxyisovalerophenone (3), was isolated from strawberry fruit along with kaempferol-3-beta-D-(6-O-trans-p-coumaroyl)glucopyranoside (1) and kaempferol-3-beta-D-(6-O-cis-p-coumaroyl)glucopyranoside (2). Compounds 1 and 2 inhibited activity of a drug-metabolizing enzyme, CYP3A4.

Cytochrome P-450 CYP3A↗
PubMed2004

Girolline, an antitumor compound isolated from a sponge, induces G2/M cell cycle arrest and accumulation of polyubiquitinated p53.

Girolline, an antitumor compound isolated from a sponge, has been reported to inhibit the termination step of protein synthesis in vivo. In this study, we found that girolline induced G2/M cell cycle arrest in several tumor cell lines. Immunochemical analysis revealed that polyubiquitinated p53 was accumulated in girolline-treated cells, while other polyubiquitinated cellular proteins were not accumulated, indicating that the effect of girolline is specific for p53. On the other hand, girolline did not inhibit proteasome activity in vitro, and accumulation of polyubiquitinated p53 was scarcely detected in the presence of leptomycin B, an inhibitor of nuclear export. Based on the above findings, we propose that girolline affects the step of recruitment of polyubiquitinated p53 to the proteasome.

Animals↗
PubMed2003

Three new cytotoxic sesterterpenes from a marine sponge Spongia sp.

Three new sesterterpenes (1-3) were isolated from a marine sponge of the genus Spongia, and their structures were determined on the basis of spectroscopic analysis. The compounds 1-3 exhibited cytotoxicity against HeLa cells with IC(50) values of 19.5, 15.0, and 5.3 microg/mL, respectively.

Animals↗
PubMed2003

New polyhydroxy sterols: proteasome inhibitors from a marine sponge Acanthodendrilla sp.

Seven new polyhydroxylated sterols, as well as the known agosterols A, C, and D2 (8-10), were isolated from a marine sponge Acanthodendrilla sp. as proteasome inhibitors. Their structures were elucidated on the basis of their spectral data, and they were characterized as agosterol congeners, which had been initially isolated from a marine sponge Spongia sp. and reported to reverse multidrug resistance in tumor cells. Among them, agosterol C (9) most strongly inhibited chymotrypsin-like activity of the proteasome with an IC50 value of 10 microg/mL.

Animals↗
PubMed2003

Tricholomalides A-C, new neurotrophic diterpenes from the mushroom Tricholoma sp.

Three new diterpenes, tricholomalides A-C (1-3), were isolated from the methanol extract of the fruiting body of Tricholoma sp. Their structures were elucidated on the basis of their spectral data, and the absolute configuration of 1 was determined by CD spectrum. Tricholomalides 1-3 significantly induced neurite outgrowth in rat pheochromocytoma cells (PC-12) at concentrations of 100 microM.

Agaricales↗
PubMed2003

Crystal structure of dissymmetrically trihydrated N,N',N''-tribenzoylmelamine (TBM).

In the crystal structure of TBM-trihydrate three waters of crystallization were found to locate dissymmetrically. Thus, one of them forms a chelated ring with the neighboring C=O and N-H of TBM. Two other ones bind each other through hydrogen bonding and two sets of which form a cyclic dimer by hydrogen bonding (namely, water-tetramer). A C=O group binds by hydrogen bonding to each of the tetrameric water. The spatial volume occupied by water-tetramer appears to be sufficient for complexation with organic molecules.

Journal Article↗
PubMed2003

Crystal structure of Diels-Alder cycloadduct formed from 1-(1,2,3-1H-benzotriazol-1-yl)-2-(4-methylphenyl)-2H-isoindole and dimethyl acetylenedicarboxylate.

The structure of the Diels-Alder cycloadduct formed from 2-(1,2,3-1H-benzotriazol-1-yl)-2-(p-tolyl)-2H-isoindole and dimethyl acetylenedicarboxylate was proved as 11-aza-1-(1,2,3-1H-benzotriazol-1-yl)-11-(4-methylphenyl)-tricyclo-[5.2.1.0(2.7)]undeca-2,4,6.9-tetraene-9,10-dioic acid dimethyl ester. The benzotriazole moiety was located as its 1-yl form, analogous to previous reports. The benzotriazole and the benzene (of tricyclo framework) planes were twisted with an angle of 115.83 degrees. Intramolecular close contacts between benzotriazole and ester are characteristic [N(3)...C(26), 2.754(3)A; N(3)...H(22), 3.26(4)A]. The shortest contact of N(3)...H(22) accounting for the rotation of the methyl group is estimated to be 3.10 A, which might be reasonable as C-H...N-type hydrogen bonding.

Journal Article↗
PubMed2002

Dihydroxybergamottin caproate as a potent and stable CYP3A4 inhibitor.

We investigated the inhibitory activity of the furanocoumarin derivatives from grapefruit juice to the drug metabolizing enzyme, cytochrome P450 (CYP) 3A4. Although two known furanocoumarin dimers GF-I-1 (1) and GF-I-4 (2) showed potent CYP3A4 inhibition with IC50 value of 0.07 microM, a semi-synthetic dihydroxybergamottin caproate (11), which was more stable and more simple than the dimers, exhibited comparable activity against CYP3A4.

Caproates↗
PubMed2002

CYP3A4 inhibitory activity of new bisalkaloids, dipiperamides D and E, and cognates from white pepper.

Two new bisalkaloids, dipiperamides D and E, were isolated as inhibitors of a drug metabolizing enzyme cytochrome P450 (CYP) 3A4 from the white pepper, Piper nigrum. Their structures were elucidated by spectroscopic methods. Dipiperamides D and E showed potent CYP3A4 inhibition with IC(50) values of 0.79 and 0.12 microM, respectively, and other metabolites from the pepper were moderately active or inactive.

Alkaloids↗