ABSTRACT
Because carbohydrates and proteins bind with such low affinity, the nature of their interactions is not clear. Photoaffinity labeling with diazirin groups is useful for elucidating the roles of carbohydrates in these binding processes. However, when carbohydrate probes are synthesized according to this conventional method, the reducing terminus of the sugar is opened to provide an acyclic structure. Because greater elucidation of carbohydrate-protein interactions requires a closed-ring carbohydrate in addition to the photoreactive group, we synthesized new molecular tools. The carbohydrate ligands were synthesized in three steps (glycosylation with allyl alcohol, deprotection, and ozonolysis). Specific binding proteins for carbohydrate ligands were obtained by photoaffinity labeling. Closed ring-type carbohydrate ligands, in which the reducing sugar is closed, bound to lectins more strongly than open ring-type sugars. Carbohydrate to protein binding was observed using AFM.
Subject(s)
Carbohydrates/chemistry , Lectins/chemistry , Photoaffinity Labels/chemistry , Azirines/chemistry , Dihydropyridines/chemistry , Ligands , Microscopy, Atomic Force , Photoaffinity Labels/chemical synthesis , Photoaffinity Labels/pharmacology , Protein BindingABSTRACT
In this study, we analyzed the CYP3A inhibitory components of star fruit Averrhoa carambola L., using liquid chromatography-mass spectrometry (LC-MS). The stereoisomer of procyanidin B1 and B2 and/or the trimer consisting of catechin and/or epicatechin were suggested to be potent inhibitory components.
Subject(s)
Cytochrome P-450 Enzyme Inhibitors , Magnoliopsida/chemistry , Plant Extracts/pharmacology , Biflavonoids/isolation & purification , Biflavonoids/pharmacology , Catechin/isolation & purification , Catechin/pharmacology , Chromatography, Liquid , Cytochrome P-450 CYP3A , Fruit , Humans , In Vitro Techniques , Mass Spectrometry , Microsomes, Liver/enzymology , Microsomes, Liver/metabolism , Plant Extracts/chemistry , Proanthocyanidins/isolation & purification , Proanthocyanidins/pharmacology , StereoisomerismABSTRACT
Six phenolic compounds were isolated from the flowers of Trachelospermum asiaticum var. intermedium (Apocynaceae). These structures were determined on the basis of spectral data.
Subject(s)
Apocynaceae/chemistry , Phenols/isolation & purification , Plant Extracts/chemistry , Flowers , Magnetic Resonance SpectroscopyABSTRACT
(2S, 3S)-Taxifolin 3-O-arabinoside, a new dihydroflavonol glycoside, together with the known substances, (2R 3R)-taxifolin 3-O-arabinoside, astragalin, isoquercitrin, and cosmosiin, were isolated from the leaves of Trachelospermum jasminoides var. pubescens. Structural elucidation was carried out by spectroscopic methods, and the absolute configurations of C-2 and C-3 in taxifolin 3-O-arabinosides were determined on the basis of circular dichroism. Unlike the dihydroflavonol glycosides, (2R 3R)-taxifolin 3-O-glucoside and (2R, 3R-taxifolin 3-O-arabinoside, the novel (2S, 3S)-taxifolin 3-O-arabinoside is not effective as a zoospore attractant of the plant pathogenic fungus Aphanomyces cochlioides.
Subject(s)
Apocynaceae/chemistry , Glycosides/chemistry , Chromatography, High Pressure Liquid , Circular Dichroism , Molecular Structure , Plant Leaves/chemistry , Spectrometry, Mass, Fast Atom Bombardment , Spectrophotometry, UltravioletABSTRACT
The present study was conducted to identify cytochrome P450 3A (CYP3A) inhibitory components of Hyuganatsu, Citrus tamurana Hort., by investigating the effects on midazolam 1'-hydroxylase activity of human liver microsomes. As a consequence, limonin and nomilin were identified as CYP3A inhibitors from the endocarp of Hyuganatsu.
ABSTRACT
A modified procedure for determining absolute configurations using an induced CD method and molecular mechanics calculations is disclosed. The practical usefulness of the present technique was demonstrated by its application to a few natural products.
Subject(s)
Biological Products/chemistry , Circular Dichroism/methods , Models, Molecular , Computational Biology , Molecular Structure , Nuclear Magnetic Resonance, Biomolecular , Rubiaceae/chemistryABSTRACT
We recently isolated 4-nitrophenol, 2-methyl-4-nitrophenol, 3-methyl-4-nitrophenol, and 4-nitro-3-phenylphenol from diesel exhaust particles (DEP) and identified them as vasodilators. Because these compounds are alkylphenolic derivatives that might mimic hormones, we evaluated their estrogenic activity by human estrogen receptor (hER)-yeast screen assay. All of these nitrophenol derivatives except 2-methyl-4-nitrophenol exhibited estrogenic activity. Some estrogenic compounds are also anti-androgenic, so we measured the anti-androgenic activity of the same compounds by human androgen receptor (hAR)-yeast screen assay. We found anti-androgenicity in all four nitrophenols. Nitrophenols in DEP possess not only vasodilatory activity but also estrogenic and anti-androgenic activity.
Subject(s)
Androgen Receptor Antagonists , Estrogens/pharmacology , Hormone Antagonists/pharmacology , Nitrophenols/pharmacology , Vehicle Emissions , Androgens/metabolism , Dose-Response Relationship, Drug , Humans , Receptors, Androgen/metabolism , Receptors, Estrogen/metabolism , Vehicle Emissions/adverse effects , Yeasts/drug effects , Yeasts/metabolismABSTRACT
In our continuing studies on estrogenic compounds in diesel exhaust particles (DEP), we have reported the systematic separation of alkyldibenzothiophenes from the estrogenic hexane fraction of DEP. In this study, another estrogenic fraction was further isolated and characterized. DEP were roughly fractionated by successive extraction with hexane, benzene, dichloromethane, methanol, 1 M ammonia and 1 M HCl. The hexane extract, which exhibited estrogenic activity, was further fractionated by column chromatography and high performance liquid chromatography (HPLC). From one of the obtained fractions that showed estrogenic activity, three alkyltrimethylbenzenes were identified by gas chromatography-mass spectrometry (GC-MS) and 1H-nuclear magnetic resonance (NMR) spectroscopy.
Subject(s)
Benzene Derivatives/chemistry , Benzene Derivatives/pharmacology , Vehicle Emissions/analysis , Environmental Monitoring , Estrogens/pharmacology , Gas Chromatography-Mass Spectrometry , Hexanes/chemistry , Magnetic Resonance Spectroscopy , Solvents/chemistryABSTRACT
The compounds in diesel exhaust particles (DEP) that are responsible for vasodilatation were isolated and characterized for the first time. From benzene extract of DEP, 2-methyl-4-nitrophenol, 3-methyl-4-nitrophenl and 4-nitrophenol were isolated, and their vasodilatation activities were confirmed. 3-methyl-4-nitrophenol caused dilatation of rat thoracic artery, and the other two nitrophenols, also showed vasodilatation activities.
Subject(s)
Air Pollutants/toxicity , Nitrophenols/toxicity , Vasodilation/drug effects , Vehicle Emissions/toxicity , Animals , Arteries/drug effects , Isotonic Contraction/drug effects , Nitrophenols/chemistry , Nitrophenols/classification , Nitrophenols/isolation & purification , Rats , Rats, Inbred F344ABSTRACT
The threo and erythro forms of guaiacylglycerol-7'-O-methyl 8'-vanillic acid ethers, threo and erythro guaiacylglycerol 8'-vanillin ethers, and threo guaiacylglycerol 8'-(4-hydroxymethyl-2-methoxyphenyl) ether have been isolated from fruits of Boreava orientalis. Structural determinations were made on the basis of UV, MS, 1H- and 13C-NMR spectral data, including two-dimensional shift correlation. The relative configurations were assigned on the basis of 1H-NMR chemical shifts.
Subject(s)
Brassicaceae/chemistry , Guaifenesin/analogs & derivatives , Guaifenesin/analysis , Guaifenesin/chemistry , Magnetic Resonance Spectroscopy , Molecular StructureABSTRACT
Taxifolin 3-O-glucoside isomers, [(2R, 3R)-, (2R, 3S)-, (2S, 3R)- and (2S, 3S)-] were isolated from leaves of Chamaecyparis obtuse (Cupressaceae). Their structures were elucidated on the basis of UV, MS, CD, 1H- and 13C-NMR spectral data, including 2D shift correlation. It was found that the compounds could be distinguished by the use of 1H- and 13C-NMR spectral data.
Subject(s)
Chamaecyparis/chemistry , Glucosides/chemistry , Glucosides/isolation & purification , Quercetin/analogs & derivatives , Quercetin/chemistry , Quercetin/isolation & purification , Chromatography, High Pressure Liquid , Circular Dichroism , Japan , Medicine, Traditional , Molecular Structure , Nuclear Magnetic Resonance, Biomolecular , StereoisomerismABSTRACT
In a previous study, we focused on estrogenic activity of the hexane extract of diesel exhaust particles (DEP). The extract of hexane was first fractionated to acidic, phenolic and neutral portions according to their chemical properties, of which the neutral fraction was fractionated by column chromatography on silica gel. The chemical structures of compounds in these fractions were then analyzed. It was found that the neutral fraction of the hexane extract of DEP contains dibenzothiophene derivatives, one of which, 4,6-dimethyldibenzothiophene, possesses estrogenic activity.
Subject(s)
Estrogens, Non-Steroidal/toxicity , Vehicle Emissions/toxicity , Estrogens, Non-Steroidal/chemistry , Gas Chromatography-Mass Spectrometry , Humans , Indicators and Reagents , Magnetic Resonance Spectroscopy , Mass Spectrometry , Receptors, Estrogen/metabolism , Saccharomyces cerevisiae , Thiophenes/chemistry , Thiophenes/toxicity , Vehicle Emissions/analysisABSTRACT
In an earlier study using a recombinant yeast screen we found that a suspension of diesel exhaust particles (DEP) and some extracts of DEP are not estrogenic but possess anti-estrogenic activity. In the present study, estrogenic and anti-estrogenic activities of two types of DEP, type-1 (old type) and type-2 (new type) were compared. Whole DEP of both types were found to possess estrogenic and anti-estrogenic activities. The DEP were serially extracted with organic solvents and then with 1 M ammonia and 1 M HCl. In type-2 DEP, the ratio of dry weight of a hexane extract was higher than those of methanol and ammonia extracts, which were lower than those in type-1 DEP. In the hexane extract, estrogenic activity was found in both types of DEP. In the benzene and dichloromethane extracts, estrogenic and anti-estrogenic activities were found in both types of DEP. In the methanol extract, estrogenic activity was found in type-2 DEP, and extracts of both types decreased the activity of estrogen. Anti-estrogenic activity was found in extracts of ammonia and HCl from both types of DEP. It was found that both type-1 and type-2 DEP possess estrogenic and anti-estrogenic activities.
