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Takao Tanahashi

Publications and source records attributed to Takao Tanahashi.

18 recordsLinked to original sources
PubMed2005

Quantitative structure-activity relationship studies for antioxidant hydroxybenzalacetones by quantum chemical- and 3-D-QSAR(CoMFA) analyses.

Antioxidant activities for a series of hydroxybenzalacetones, OH-BZ, evaluated by their inhibitory potencies against lipid peroxidation induced by gamma-ray irradiation or t-BuOOH, were analyzed quantitatively using quantum-chemical parameters calculated by semi-empirical molecular orbital (MO) calculations. The energy of the highest occupied molecular orbital (E(HOMO)) and frontier electron densities (HOMO) on the phenolic oxygen atom (F(H,O)), together with the steric parameter (E(s)) for the substituent ortho to the phenolic oxygen, showed excellent correlations. We also performed 3D-QSAR studies by using the comparative molecular field analysis (CoMFA) model. The results were compared with the corresponding classical QSAR correlations.

Acetone↗
PubMed2005

Monomeric and dimeric dibenzofurans from cultured mycobionts of Lecanora iseana.

Spore-derived mycobionts of the lichen Lecanora iseana were cultivated on a malt-yeast extract medium supplemented with 10% sucrose and their metabolites were investigated. Four 3,7-dihydroxy-1,9-dimethyldibenzofuran derivatives along with the known 3,7-dihydroxy-1,9-dimethyldibenzofuran and five norlichexanthone derivatives were isolated. Their structures were determined by spectroscopic methods.

Benzofurans↗
PubMed2005

Indole alkaloids and other constituents of Rauwolfia serpentina.

From the dried roots of Rauwolfia serpentina were isolated five new indole alkaloids, N(b)-methylajmaline (1), N(b)-methylisoajmaline (2), 3-hydroxysarpagine (3), yohimbinic acid (4), isorauhimbinic acid (5), a new iridoid glucoside, 7-epiloganin (6), and a new sucrose derivative, 6'-O-(3,4,5-trimethoxybenzoyl)glomeratose A (7), together with 20 known compounds. The structures of the new compounds were determined by spectroscopic and chemical means. The inhibitory activities of the selected alkaloids on topoisomerase I and II and their cytotoxicity against the human promyelocytic leukemia (HL-60) cell lines were assessed.

Antineoplastic Agents, Phytogenic↗
PubMed2005

Secoiridoid glucosides from Strychnos spinosa.

Three new secoiridoid glucosides, stryspinoside (1) and strychosides A (2) and B (3), were isolated, together with 23 known compounds, from the dried branches of Strychnos spinosa. The structures of the new compounds were determined by spectroscopic means.

Glucosides↗
PubMed2005

Hydrogen-bonding abilities for phenols assessed by quantitative analyses of their partition coefficients derived from different partitioning systems.

We recently proposed a new hydrogen-accepting scale, S(HA), on the basis of the heat of formation calculated by the conductor-like screening model (COSMO) method. In this work, the same approach was applied to a series of compounds with a common hydrogen-donor group. Thus the S(HA) values for monosubstituted phenols were calculated and used for correlating their log P(oct) values (P(oct): 1-octanol/water partition coefficient) with log P(CL) (P(CL): chloroform/water partition coefficient) and log P(E) (P(E): butyl ether/water partition coefficient). It was demonstrated that the S(HA) parameter works effectively, providing excellent correlations whose physicochemical meanings are well rationalized in terms of hydrogen-bonding characteristics of the substituents.

Algorithms↗
PubMed2004

Quantitative structure-activity relationship analyses of antioxidant and free radical scavenging activities for hydroxybenzalacetones.

Antioxidant activities for a series of hydroxybenzalacetones, OH-BZ, were evaluated by measuring inhibitory potencies of OH-BZ against lipid peroxidation induced by t-BuOOH or gamma-irradiation. Their quantitative structure-activity relationship (QSAR) studies indicated that the activities are mainly governed by electronic and steric factors. To rationalize these results, we also performed QSAR analyses for DPPH radical scavenging activities of OH-BZ, which indicated that antioxidant and radical scavenging activities could be expressed by the same physicochemical parameters but the hydrogen bonding behavior of phenolic OH varies with the reaction medium.

Animals↗
PubMed2004

Detection and determination of reticuline and N-methylcoculaurine in the Annonaceae family using liquid chromatography-tandem mass spectrometry.

In Guadeloupe, the French West Indies, there is a high incidence of atypical parkinsonism or progressive supranuclear palsy, and all of the investigated patients had taken herbal tea or tropical fruits of the Annonaceae family. Local inhabitants consume the fruits, and also drink tea made from the leaves. In the present study, we used liquid chromatography-tandem mass spectrometry (LC/MS/MS) with multiple reaction monitoring (MRM) to detect low-molecular-weight neurotoxic benzylisoquinoline derivatives in the Annonaceae family. We detected reticuline and N-methylcoculaurine in every Annona muricata sample examined, except for pulp and seed. They were not detected in sweetsop fruits. Norreticuline was not detected in any sample. These three compounds were toxic to SH-SY5Y neuroblastoma cells and inhibited mitochondrial respiratory complex I. It is possible that uptake of the benzylisoquinoline derivatives reticuline and N-methylcoculaurine and their accumulation in the brain may be related to the pathogenesis of the local endemic disease.

Alkaloids↗
PubMed2004

Flavonoid glycosides from Adina racemosa and their inhibitory activities on eukaryotic protein synthesis.

From the dried leaves, flowers, and twigs of Adina racemosa, five new flavonoid glycosides, quercetin 3-O-alpha-l-rhamnopyranosyl(1-->6)-(3-O-trans-p-coumaroyl)-beta-d-galactopyranoside (1), quercetin 3-O-alpha-l-rhamnopyranosyl(1-->6)-[(4-O-trans-p-coumaroyl)-alpha-l-rhamnopyranosyl(1-->2)]-(4-O-trans-p-coumaroyl)-beta-d-galactopyranoside (2), kaempferol 3-O-alpha-l-rhamnopyranosyl(1-->6)-[(4-O-trans-p-coumaroyl)-alpha-l-rhamnopyranosyl(1--> 2)]-(4-O-trans-p-coumaroyl)-beta-d-galactopyranoside (3), quercetin 3-O-alpha-l-rhamnopyranosyl(1-->6)-[(4-O-trans-p-coumaroyl)-alpha-l-rhamnopyranosyl(1-->2)]-(3-O-trans-p-coumaroyl)-beta-d-galactopyranoside (4), and quercetin 3-O-alpha-l-rhamnopyranosyl(1-->6)-[(4-O-trans-caffeoyl)-alpha-l-rhamnopyranosyl(1-->2)]-(3-O-trans-p-coumaroyl)-beta-d-galactopyranoside (5), and eight known compounds were isolated. The structures of the new compounds were determined by spectroscopic and chemical means. Their inhibitory activities on protein synthesis were assessed. The new glycosides were found to be inhibitors of eukayrotic, but not prokaryotic, protein synthesis.

Eukaryotic Cells↗
PubMed2003

6H-dibenzo[b,d]pyran-6-one derivatives from the cultured lichen mycobionts of Graphis spp. and their biosynthetic origin.

The spore-derived mycobionts of the lichen Graphis prunicola, G. cognata and G. scripta were cultivated on a malt-yeast extract medium supplemented with 10% sucrose and their metabolites were investigated. Graphislactones A-D were isolated from the cultures of G. prunicola, while alternariol and graphislactones A and C were isolated from those of G. cognata. From the cultured mycobionts of G. scripta, a new 6H-dibenzo[b,d]pyran-6-one derivative, graphislactone E with graphislactones A and C was obtained. On the other hand, cultivation of the mycobionts of G. prunicola on a malt-yeast extract medium supplemented with 2.5% sucrose and 0.25% sodium acetate produced two new metabolites, graphislactones E and F. Their structures were determined by spectroscopic methods. The biogenetic origin of the carbon skeleton in both compounds was verified by administering sodium [1-13C]-acetate and sodium [1,2-13C(2)]-acetate.

Lactones↗
PubMed2003

Two chromone-secoiridoid glycosides and three indole alkaloid glycosides from Neonauclea sessilifolia.

From the dried roots of Neonauclea sessilifolia, two new chromone-secoiridoid glycosides, sessilifoside and 7"-O-beta-D-glucopyranosylsessilifoside, and three novel indole alkaloid glycosides, neonaucleosides A, B, and C, were isolated along with the main known glycosides, 5-hydroxy-2-methylchromone-7-O-beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside, sweroside, loganin, grandifloroside, and quinovic acid 3 beta-O-beta-D-quinovopyranoside-28-O-beta-D-glucopyranoside. The structures of these new glycosides were determined by spectroscopic and chemical means. Neonaucleoside A and its C-3 epimer were prepared from secologanin and tryptamine.

Glycosides↗
PubMed2003

Six secoiridoid glucosides from Adina racemosa.

Six novel secoiridoid glucosides, adinosides A (1), B (2), C (3), D (4), E (5), and grandifloroside 11-methyl ester (6) were isolated, together with 27 known compounds, from the dried leaves, flowers, and twigs of Adina racemosa. The structures of the new compounds were determined by spectroscopic (NMR, MS) and chemical means.

Iridoids↗
PubMed2003

Two triterpenoid saponins from Neonauclea sessilifolia.

From the dried roots of Neonauclea sessilifolia (Rubiaceae), two new triterpenoid saponins, 3-O-beta-D-glucopyranosyl-(1-->2)-beta-D-quinovopyranosyl quinovic acid (1) and 3-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-quinovopyranosyl pyrocincholic acid 28-O-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl ester (2), were isolated, together with five known saponins. The structures of the new saponins were determined by spectroscopic and chemical means.

Hydrolysis↗
PubMed2003

Phenyl ethers from cultured lichen mycobionts of Graphis scripta var. serpentina and G. rikuzensis.

Spore-derived mycobionts of the lichen Graphis scripta var. serpentina and G. rikuzensis were cultivated on a malt-yeast extract medium supplemented with 10% sucrose and their metabolites were investigated. 3,3'-Dihydroxy-5,5'-dimethyldiphenyl ether was isolated from the cultures of the mycobionts of G. scripta var. serpentina, while a new phenyl ether, rikuzenol, along with two known diphenyl ethers, violaceol-I and violaceol-II, were isolated from those of G. rikuzensis. The structure of the new compound was determined by spectroscopic methods. Violaceol-I was chemically synthesized and interconversion between violaceol-I and violaceol-II was proven.

Lichens↗
PubMed2002

Tetrahydroisoquinoline-monoterpene glycosides from Cephaelis acuminata.

From the dried roots of Cephaelis acuminata, five tetrahydroisoquinoline-monoterpene glycosides, 2-O-beta-D-glucopyranosyldemethylalangiside, demethylisoalangiside, 6"-O-beta-D-glucopyranosylipecoside, 6"-O-alpha-D-glucopyranosylipecoside and (4R)-4-hydroxyipecoside, were isolated. The structures of these glycosides were determined by spectroscopic and chemical means.

Alkaloids↗
PubMed2002

Secoiridoid and iridoid glucosides from Syringa afghanica.

Phytochemical investigation of the dried leaves of Syringa afghanica, has led to the isolation of nine secoiridoid glucosides, safghanosides A-H and 2"-epi-frameroside, as well as an iridoid glucoside, syringafghanoside along with nineteen known compounds. The structures were elucidated by spectroscopic and chemical means.

Glucosides↗
PubMed2002

Flavonoid glycosides from Rhazya orientalis.

Six new flavonoid glycosides, quercetin 3-O-alpha-L-rhamnopyranosyl(1-->6)-[alpha-L-rhamnopyranosyl(1-->2)]-(4-O-trans-p-coumaroyl)-beta-D-galactopyranoside-7-O-alpha-L-rhamnopyranoside (1), quercetin 3-O-alpha-L-rhamnopyranosyl(1-->6)-[alpha-L-rhamnopyranosyl(1-->2)]-(3-O-trans-p-coumaroyl)-beta-D-galactopyranoside-7-O-alpha-L-rhamnopyranoside (2), isorhamnetin 3-O-alpha-L-rhamnopyranosyl(1-->6)-[alpha-L-rhamnopyranosyl(1-->2)]-(4-O-trans-p-coumaroyl)-beta-D-galactopyranoside-7-O-alpha-L-rhamnopyranoside (3), isorhamnetin 3-O-alpha-L-rhamnopyranosyl(1-->6)-[alpha-L-rhamnopyranosyl(1-->2)]-(3-O-trans-p-coumaroyl)-beta-D-galactopyranoside-7-O-alpha-L-rhamnopyranoside (4), isorhamnetin 3-O-alpha-L-rhamnopyranosyl(1-->6)-[alpha-L-rhamnopyranosyl(1-->2)]-(4-O-cis-p-coumaroyl)-beta-D-galactopyranoside-7-O-alpha-L-rhamnopyranoside (5), and isorhamnetin 3-O-alpha-L-rhamnopyranosyl(1-->6)-[alpha-L-rhamnopyranosyl(1-->2)]-(4-O-trans-feruloyl)-beta-D-galactopyranoside-7-O-alpha-L-rhamnopyranoside (6), were isolated from the dried aerial parts of Rhazya orientalis. The structures of 1-6 were determined by spectroscopic and chemical means.

Apocynaceae↗
PubMed2002

Nine new secoiridoid glucosides from Jasminum nudiflorum.

Phytochemical study of the leaves of Jasminum nudiflorum has led to the isolation of nine new secoiridoid glucosides, jasnudiflosides F-L (1-7), nudifloside D (8) and isooleoacteoside (9). The structures of these compounds were elucidated on the basis of chemical and spectroscopic evidence.

Carbohydrate Conformation↗