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Biomedical subjects

V Wray

Publications and source records attributed to V Wray.

At least 37 records · Page 2Linked to original sources
PubMed2000

Betalains from Christmas cactus.

The presence of 14 betalain pigments have been detected by their characteristic spectral properties in flower petals of Christmas cactus (Schlumbergera x buckleyi). Along with the known vulgaxanthin I, betalamic acid, betanin and phyllocactin (6'-O-malonylbetanin), the structure of a new phyllocactin-derived betacyanin was elucidated by various spectroscopic techniques and carbohydrate analyses as betanidin 5-O-(2'-O-beta-D-apiofuranosyl-6'-O-malonyl)-beta-D-glucopyranosid e. Among the more complex betacyanins occurring in trace amounts, the presence of a new diacylated betacyanin ¿betanidin 5-O-[(5"-O-E-feruloyl)-2'-O-beta-D- apiofuranosyl-6'-O-malonyl)]-beta-D-glucopyranoside¿ has been ascertained. Furthermore, the accumulation of betalains during flower development and their pattern in different organs of the flower has been examined.

Betalains↗
PubMed2000

Insecticidal rocaglamide derivatives from Aglaia spectabilis (Meliaceae).

Bark of Aglaia spectabilis collected on the island of Phu Quoc (Vietnam) yielded insecticidal cyclopentatetrahydrobenzofurans of the rocaglamide type including four new natural products. Structure elucidation of the new compounds is described. All rocaglamide derivatives isolated exhibited strong insecticidal activity towards neonate larvae of the polyphagous pest insect Spodoptera littoralis when incorporated into an artificial diet. LC50 values varied from 0.8 to 80 ppm. The most active compounds isolated, methylrocaglate and C-3' hydroxylmethylrocaglate, were similar with regard to their insecticidal activity to the well-known natural insecticide azadirachtin.

Benzofurans↗
PubMed2000

Production and structure elucidation of glycoglycerolipids from a marine sponge-associated microbacterium species.

The bacterium Microbacterium sp., isolated from the sponge Halichondria panicea, produced four unusual cell-associated glycoglycerolipids and one diphosphatidylglycerol when grown on marine broth and on artificial seawater media. The lipids were isolated by chromatography on silica columns and their structures elucidated using a combination of multidimensional NMR and MS techniques. The main compound was 1-O-acyl-3-[alpha-glucopyranosyl-(1-3)-(6-O-acyl-alpha-mannopyranosyl )]glycerol (GGL.2) with 14-methyl-hexadecanoic acid and 12-methyl-tetradecanoic acid positioned at C-6 of the mannose unit and at the glycerol moiety. Glycolipid production was correlated with growth and reached a maximum value of 200 mg/L when grown on artificial seawater medium with 20 g/L glucose. The main compound decreased the surface tension of water down to 33 mN/m and the interfacial tension of the water/n-hexadecane system down to 5 mN/m. In addition to this good surface-active behavior, the main glycoglycerolipid showed antitumor activities.

Actinomycetales↗
PubMed2000

Anthraquinones and betaenone derivatives from the sponge-associated fungus Microsphaeropsis species: novel inhibitors of protein kinases.

An undescribed fungus of the genus Microsphaeropsis, isolated from the Mediterranean sponge Aplysina aerophoba, produces two new betaenone derivatives (1, 2) and three new 1,3,6, 8-tetrahydroxyanthraquinone congeners (5-7). The structures of the compounds were established on the basis of NMR spectroscopic and mass spectrometric data and by CD spectroscopy. This is the first report wherein the (1)H and (13)C NMR data of the betaenone congeners are fully and unambiguously assigned on the basis of two-dimensional NMR spectroscopy. Furthermore, we describe the first elucidation of the absolute configuration of 1-(2'-anthraquinonyl)ethanols such as 5 and 6, by quantum chemical calculation of their circular dichroism (CD) and comparison with experimentally measured spectra. Moreover, it was shown that compounds 1, 5, 6, and 7 are inhibitors of PKC-epsilon, CDK4, and EGF receptor tyrosine kinases.

Animals↗
PubMed2000

Monodesmosidic saponins from Herniaria hirsuta.

Two new monodesmosidic saponins, herniaria saponins E and F, were isolated from the aerial parts of Herniaria hirsuta. On the basis of chemical and spectral evidence, their structures were established to be 2-O-acetyl medicagenic acid 28-O-beta-D-xylopyranosyl- (1-->4)-alpha-L-rhamnopyranosyl(1-->2)-[beta-D-glucopyranosyl(1-->6)]-be ta- D-glucopyranoside (herniaria saponin E, 1) and medicagenic acid 28-O-beta-D-xylopyranosyl(1-->4)-alpha-L- rhamnopyranosyl(1-->2)-[alpha-L-rhamnopyranosyl-(1-->4)-beta-D- glucopyranosyl-(1-->6)]-beta-D-glucopyranoside (herniaria saponin F, compound 2).

Carbohydrate Sequence↗
PubMed1999

Solution structure and orientation of the transmembrane anchor domain of the HIV-1-encoded virus protein U by high-resolution and solid-state NMR spectroscopy.

The structure of the membrane anchor domain (VpuMA) of the HIV-1-specific accessory protein Vpu has been investigated in solution and in lipid bilayers by homonuclear two-dimensional and solid-state nuclear magnetic resonance spectroscopy, respectively. Simulated annealing calculations, using the nuclear Overhauser enhancement data for the soluble synthetic peptide Vpu1-39 (positions Met-1-Asp-39) in an aqueous 2,2,2-trifluoroethanol (TFE) solution, afford a compact well-defined U-shaped structure comprised of an initial turn (residues 1-6) followed by a linker (7-9) and a short helix on the N-terminal side (10-16) and a further longer helix on the C-terminal side (22-36). The side chains of the two aromatic residues (Trp-22 and Tyr-29) in the longer helix are directed toward the center of the molecule around which the hydrophobic core of the folded VpuMA is positioned. As the observed solution structure is inconsistent with the formation of ion-conductive membrane pores defined previously for VpuMA in planar lipid bilayers, the isolated VpuMA domain as peptide Vpu1-27 was investigated in oriented phospholipid bilayers by proton-decoupled 15N cross polarization solid-state NMR spectroscopy. The line widths and chemical shift data of three selectively 15N-labeled peptides are consistent with a transmembrane alignment of a helical polypeptide. Chemical shift tensor calculations imply that the data sets are compatible with a model in which the nascent helices of the folded solution structure reassemble to form a more regular linear alpha-helix that lies parallel to the bilayer normal with a tilt angle of </=30 degrees. The arrangement of the membrane-associated structures described previously for the cytoplasmic domain and for the anchor domain of Vpu identified in this work is discussed.

Amino Acid Sequence↗
PubMed1999

The solution structure of a [3Fe-4S] ferredoxin: oxidised ferredoxin II from Desulfovibrio gigas.

The use of standard 2D NMR experiments in combination with 1D NOE experiments allowed the assignment of 51 of the 58 spin systems of oxidised [3Fe4S] ferredoxin isolated from Desulfovibrio gigas. The NMR solution structure was determined using data from 1D NOE and 2D NOESY spectra, as distance constraints, and information from the X-ray structure for the spin systems not detected by NMR in torsion angle dynamics calculations to produce a family of 15 low target function structures. The quality of the NMR family, as judged by the backbone r.m.s.d. values, was good (0.80 A), with the majority of phi/psi angles falling within the allowed region of the Ramachandran plot. A comparison with the X-ray structure indicated that the overall global fold is very similar in solution and in the solid state. The determination of the solution structure of ferredoxin II (FdII) in the oxidised state (FdIIox) opens the way for the determination of the solution structure of the redox intermediate state of FdII (FdII(int)), for which no X-ray structure is available.

Amino Acid Sequence↗
PubMed1999

Light-induced betacyanin and flavonol accumulation in bladder cells of Mesembryanthemum crystallinum.

Treatment of the halophyte Mesembryanthemum crystallinum L. (ice plant) (Aizoaceae) with high intensities of white light resulted in a rapid cell-specific accumulation of betacyanins and flavonoids with 6-methoxyisorhamnetin 3-O-¿[(2"'-E-feruloyl)-3"'-O-(beta-D- glucopyranosyl)](2"-O-beta-D-xylopyranosyl)]-beta-D-glucopyranoside (mesembryanthin) as the predominant component, within bladder cells of the leaf epidermis. Induced accumulation of these metabolites was first detected 18 h after the initiation of light treatment in bladder cells located at the tip of young leaves followed by the bladder cells located on the epidermis of fully expanded leaves. UV-A light apparently is sufficient to induce accumulation of betacyanins and flavonoids. Application of 2-aminoindan 2-phosphonic acid, a specific inhibitor of phenylalanine ammonia-lyase (PAL; EC 4.3.1.5), not only inhibited the accumulation of flavonoids but also reduced betacyanin formation. Based on these observations we suggest these bladder cells as a model system to study regulation of betacyanin and flavonoid biosyntheses.

Anthocyanins↗
PubMed1999

Identification of two novel proanthocyanidins in green Tea.

The isolation and structural elucidation of epiafzelechingallate-(4beta-->8)-epicatechingallate (EAG-4beta-->8-ECG) and epiafzelechingallate-(4beta-->6)-epicatechingallate (EAG-4beta-->6-ECG) in green tea samples are described. The combination of various 2D NMR techniques allowed a full structural determination of the underivatized proanthocyanidins even though broadening of the signals did not allow observation of some key correlations that characterize the location of the interflavonoid linkage. The differences in the NMR spectra of the new compounds allowed formulation of criteria for the discrimination between the 4-->6 and 4-->8 isomers in this type of compound.

Anthocyanins↗
PubMed1999

New alkaloids from the indopacific sponge Stylissa carteri.

Two samples of the marine sponge Stylissa carteri collected in Indonesia yielded two new bromopyrrole alkaloids: debromostevensine (1) and debromohymenin (2), as well as nine other known congeners (3-11). The structures of the new compounds were unambiguously established on the basis of their NMR and mass spectra.

Alkaloids↗
PubMed1999

Silenosides A-C, triterpenoid saponins from Silene vulgaris.

Three new triterpenoid saponins named silenosides A-C (1-3) were obtained from the roots of Silene vulgaris. Their structures were elucidated by spectral and chemical methods as beta-D-galactopyranosyl(1-->2)-beta-D-glucuronopyranosyl-3beta- hydrox y-23-oxoolean-12-en-28-oic acid 28-O-beta-D-xylopyranosyl(1-->3)-beta-D-xylopyranosyl(1-->4)-alpha-L- rhamnopyranosyl(1-->2)-beta-D-fucopyranoside; 3-O-beta-D-galactopyranosyl(1-->2)-beta-D-glucuronopyranosyl-3beta , 16alpha-dihydroxy-23-oxoolean-12-en-28-oic acid 28-O-beta-D-xylopyranosyl(1-->4)-[beta-D-glucopyranosyl(1-->2)]-alpha -L-rhamnopyranosyl(1-->2)-beta-D-fucopyranoside; and 3-O-alpha-L-arabinopyranosyl(1-->3)-[beta-D-galactopyranosyl(1-->2 )]- beta-D-glucuronopyranosyl-3beta, 16alpha-dihydroxy-23-oxoolean-12-en-28-oic acid 28-O-beta-D-xylopyranosyl(1-->4)-[beta-D-glucopyranosyl(1-->2)]-alpha -L-rhamnopyranosyl(1-->2)-beta-D-fucopyranoside, respectively.

Carbohydrate Sequence↗
PubMed1999

Staurosporine derivatives from the ascidian eudistoma toealensis and its predatory flatworm pseudoceros sp

Two new indolocarbazole alkaloids, 3-hydroxy-3'-demethoxy-3'-hydroxystaurosporine (5) and 11-hydroxy-4'-N-demethylstaurosporine (6), were isolated from the marine ascidian Eudistoma toealensis and its predator, the marine flatworm Pseudoceros sp. In addition, five known derivatives were isolated in their protonated states, which caused the pyran-ring system to adopt a boat conformation. The structures were determined by 1D and 2D homonuclear and (1)H-detected heteronuclear NMR spectroscopy and from comparisons with published data. The heteronuclear correlations were necessary to establish reliable data for the structure elucidation.

Journal Article↗
PubMed1999

New bromopyrrole alkaloids from the Indopacific sponge Agelas nakamurai.

Two new dimeric bromopyrrole alkaloids, nakamuric acid (1) and its corresponding methyl ester (2), have been isolated from the Indopacific sponge Agelas nakamurai along with the known metabolites sceptrin (3), debromosceptrin (4), and ageliferin (5). Their structures were identified by analysis of spectral data. All compounds inhibited the growth of several Gram-positive and Gram-negative bacteria in the agar plate diffusion assay.

Alkaloids↗
PubMed1999

Initial reactions in the biodegradation of 1-chloro-4-nitrobenzene by a newly isolated bacterium, strain LW1.

Bacterial strain LW1, which belongs to the family Comamonadaceae, utilizes 1-chloro-4-nitrobenzene (1C4NB) as a sole source of carbon, nitrogen, and energy. Suspensions of 1C4NB-grown cells removed 1C4NB from culture fluids, and there was a concomitant release of ammonia and chloride. Under anaerobic conditions LW1 transformed 1C4NB into a product which was identified as 2-amino-5-chlorophenol by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry. This transformation indicated that there was partial reduction of the nitro group to the hydroxylamino substituent, followed by Bamberger rearrangement. In the presence of oxygen but in the absence of NAD, fast transformation of 2-amino-5-chlorophenol into a transiently stable yellow product was observed with resting cells and cell extracts. This compound exhibited an absorption maximum at 395 nm and was further converted to a dead-end product with maxima at 226 and 272 nm. The compound formed was subsequently identified by 1H and 13C NMR spectroscopy and mass spectrometry as 5-chloropicolinic acid. In contrast, when NAD was added in the presence of oxygen, only minor amounts of 5-chloropicolinic acid were formed, and a new product, which exhibited an absorption maximum at 306 nm, accumulated.

Aerobiosis↗
PubMed1999

3-nitroadipate, a metabolic intermediate for mineralization of 2, 4-dinitrophenol by a new strain of a Rhodococcus species.

The bacterial strain RB1 has been isolated by enrichment cultivation with 2,4-dinitrophenol as the sole nitrogen, carbon, and energy source and characterized, on the basis of 16S rRNA gene sequence comparison, as a Rhodococcus species closely related to Rhodococcus opacus. Rhodococcus sp. strain RB1 degrades 2,4-dinitrophenol, releasing the two nitro groups from the compound as nitrite. The release of nitro groups from 2,4-dinitrophenol occurs in two steps. First, the 2-nitro group is removed as nitrite, with the production of an aliphatic nitro compound identified by 1H nuclear magnetic resonance and mass spectrometry as 3-nitroadipate. Then, this metabolic derivative is further metabolized, releasing its nitro group as nitrite. Full nitrite assimilation upon reduction to ammonia requires that an additional carbon source be supplied to the medium.

2,4-Dinitrophenol↗
PubMed1998

Solution structure of the cytoplasmic domain of the human CD4 glycoprotein by CD and 1H NMR spectroscopy: implications for biological functions.

The human T cell receptor CD4 is a type I integral membrane glycoprotein that is involved in T cell activation and also acts as the primary coreceptor for human immunodeficiency viruses (HIV). Here the structure of a synthetic 38 amino acid peptide corresponding to the complete cytoplasmic domain of CD4 (CD4CYTO) has been investigated under a variety of solution conditions using a combination of circular dichroism and homonuclear two-dimensional 1H nuclear magnetic resonance spectroscopy. In the presence of the membrane mimetic 2,2,2-trifluoroethanol (TFE), a conformational change of CD4CYTO from a random coil to an alpha-helical structure was observed. In keeping with this, CD4CYTO has the potential to associate with membranes as demonstrated by binding studies of in vitro phosphorylated CD4CYTO with microsomal membranes. Both chemical shift and nuclear Overhauser enhancement data in 50% 2,2, 2-trifluoroethanol solution provide direct experimental evidence for the predominance of a short amphiphatic alpha-helix that is approximately 4 turns in length and extends from positions Arg-402 to Lys-417. The present data provide, for the first time, compelling experimental evidence that only a fraction of CD4CYTO has a propensity for adopting secondary structure under conditions that are assumed to exist at or near to the membrane surface and that this alpha-helical structure is located in the membrane-proximal region of CD4CYTO. The N-terminal residues, that link the alpha-helix to the transmembrane anchor of CD4, and a substantial C-terminal portion (14-18 residues) of CD4CYTO are unstructured under the solution conditions investigated. Correlation of our structural data with recent studies on the biological activity of CD4CYTO indicates that the alpha-helix is of crucial importance for the interaction of CD4 with Nef and Vpu in the process of HIV-mediated CD4 down-regulation.

Amino Acid Sequence↗