Newbouldiosides A-C, phenylethanoid glycosides from the stem bark of Newbouldia laevis

From the stem bark of Newbouldia laevis three phenylethanoid glycosides, designated as newbouldioside A-C, were isolated together with a sodium salt of analogue B and the known compounds, verbascoside, 5-hydroxydehydro-iso-alpha-lapachone, 3,8-dihydroxydehydro-iso-alpha-lapachone, apigenin and luteolin. The structures of the phenylethanoid glycosides were elucidated by spectroscopic methods as beta-(3,4-dihydroxyphenyl)ethyl 5-O-syringoyl-beta-D-apiofuranosyloxy-(1-->2)-O-[alpha-L-rhamnopyranosyl-(1-->3)]-beta-D-glucopyranoside, ss-(3,4-dihydroxyphenyl)ethyl 5-O-syringoyl-beta-D-apiofuranosyloxy-(1-->2)-O-[alpha-L-rhamnopyranosyl-(1-->3)]-6-O-E-feruloyl-beta-D-glucopyranoside, and beta-(3,4-dihydroxyphenyl)ethyl 3-O-E-feruloyl-beta-D-apiofuranosyloxy-(1-->2)-O-alpha-L-rhamnopyranosyl-(1-->2)-6-O-E-sinapoyl-beta-D-glucopyranoside, respectively.     

Newbouldiaquinone A: A naphthoquinone-anthraquinone ether coupled pigment, as a potential antimicrobial and antimalarial agent from Newbouldia laevis

The study of the chemical constituents of the roots of Newbouldia laevis (Bignoniaceae) has resulted in the isolation and characterization of a naphthoquinone-anthraquinone coupled pigment named newbouldiaquinone A (1) together with 14 known compounds: apigenin, chrysoeriol, newbouldiaquinone, lapachol, 2-methylanthraquinone, 2-acetylfuro-1,4-naphthoquinone, 2,3-dimethoxy-1,4-benzoquinone, oleanolic acid, canthic acid, 2-(4-hydroxyphenyl)ethyl triacontanoate, newbouldiamide, 5,7-dihydroxydehydroiso-alpha-lapachone, beta-sitosterol, and beta-sitosterol glucopyranoside. The structure elucidation of the isolated compounds was established based on spectroscopic studies, notably of the 2D NMR spectra. The antimalarial activity of compound (1) against Plasmodium falciparum in vitro shows moderate chemo suppression of parasitic growth. Its antimicrobial activity against a wide range of microorganisms was 13- and 24-fold more active against Candida gabrata and Enterobacter aerogens than the reference antibiotics nystatin and gentamycin.     

In vitro antioxidant capacity and free radical scavenging evaluation of active metabolite constituents of Newbouldia laevis ethanolic leaf extract

Background

The aim of the present study was to evaluate the in vitro antioxidant and free radical scavenging capacity of bioactive metabolites present in Newbouldia laevis leaf extract.

Results

Chromatographic and spectrophotometric methods were used in the study and modified where necessary in the study. Bioactivity of the extract was determined at 10 μg/ml, 50 μg/ml, 100 μg/ml, 200 μg/ml and 400 μg/ml concentrations expressed in % inhibition. The yield of the ethanolic leaf extract of N.laevis was 30.3 g (9.93%). Evaluation of bioactive metabolic constituents gave high levels of ascorbic acid (515.53 ± 12 IU/100 g [25.7 mg/100 g]), vitamin E (26.46 ± 1.08 IU/100 g), saponins (6.2 ± 0.10), alkaloids (2.20 ± 0.03), cardiac glycosides(1.48 ± 0.22), amino acids and steroids (8.01 ± 0.04) measured in mg/100 g dry weight; moderate levels of vitamin A (188.28 ± 6.19 IU/100 g), tannins (0.09 ± 0.30), terpenoids (3.42 ± 0.67); low level of flavonoids (1.01 ± 0.34 mg/100 g) and absence of cyanogenic glycosides, carboxylic acids and aldehydes/ketones. The extracts percentage inhibition of DPPH, hydroxyl radical (OH^.), superoxide anion (O₂^.-), iron chelating, nitric oxide radical (NO), peroxynitrite (ONOO⁻), singlet oxygen (¹O₂), hypochlorous acid (HOCl), lipid peroxidation (LPO) and FRAP showed a concentration-dependent antioxidant activity with no significant difference with the controls. Though, IC₅₀ of the extract showed significant difference only in singlet oxygen (¹O₂) and iron chelating activity when compared with the controls.

Conclusions

The extract is a potential source of antioxidants/free radical scavengers having important metabolites which maybe linked to its ethno-medicinal use.     

Three isocoumarins and a benzofuran from the cultured lichen mycobionts of Pyrenula sp

The spore-derived mycobionts of the lichen Pyrenula sp. were cultivated on a malt-yeast extract medium supplemented with 10% sucrose. The investigation of their metabolites resulted in isolation of four compounds, three isocoumarins and a biogenetically related benzofuran; their structures were determined by spectroscopic methods.     

New vernocuminosides from the stem barks of Vernonia cumingiana Benth

Seven new stigmastane-type steroidal glycosides, vernocuminosides A-G (1-7), have been isolated from the stem barks of Vernonia cumingiana Benth. The structural elucidation and stereochemistry determination were achieved by spectroscopic and chemical methods including 1D and 2D NMR ((1)H-(1)H COSY, HSQC, HMBC, and NOE) experiments, especially the employment of Snatzke's method expressed by the induced circular dichroism spectra. Anti-inflammatory activities and cytotoxicities of compounds 1-7 were evaluated.     

A Xenopus tropicalis oligonucleotide microarray works across species using RNA from Xenopus laevis

Microarrays have great potential for the study of developmental biology. As a model system Xenopus is well suited for making the most of this potential. However, Xenopus laevis has undergone a genome wide duplication meaning that most genes are represented by two paralogues. This causes a number of problems. Most importantly the presence of duplicated genes mean that a X. laevis microarray will have less or even half the coverage of a similar sized microarray from the closely related but diploid frog Xenopus tropicalis. However, to date, X. laevis is the most commonly used amphibian system for experimental embryology. Therefore, we have tested if a microarray based on sequences from X. tropicalis will work across species using RNA from X. laevis. We produced a pilot oligonucleotide microarray based on sequences from X. tropicalis. The microarray was used to identify genes whose expression levels changed during early X. tropicalis development. The same assay was then carried out using RNA from X. laevis. The cross species experiments gave similar results to those using X. tropicalis RNA. This was true at the whole microarray level and for individual genes, with most genes giving similar results using RNA from X. laevis and X. tropicalis. Furthermore, the overlap in genes identified between a X. laevis and a X. tropicalis set of experiments was only 12% less than the overlap between two sets of X. tropicalis experiments. Therefore researchers can work with X. laevis and still make use of the advantages offered by X. tropicalis microarrays.     

Spatially and temporally regulated alpha6 integrin cleavage during Xenopus laevis development

The α6 integrin is essential for early nervous system development in Xenopus laevis. We have previously reported a uPA cleaved form of integrin α6 (α6p), in invasive human prostate cancer tissue, whose presence correlates with increased migration and invasive capacity. We now report that α6 is cleaved during the normal development of Xenopus in a spatially and temporally controlled manner. In addition, unlike normal mammalian tissues, which lack α6p, the major form of the α6 integrin present in adult Xenopus is α6p. The protease responsible for the cleavage in mammals, uPA, is not involved in the cleavage of Xenopus α6. Finally, overexpression of a mammalian α6 mutant which cannot be cleaved leads to developmental abnormalities suggesting a potential role for the cleavage in development.     

Ferulsinaic acid, a sesquiterpene coumarin with a rare carbon skeleton from Ferula species

Fractionation of methylene chloride extracts of the resin of Ferula vesceritensis and F. sinaica afforded three sesquiterpene coumarins and a glucose derivative. One of them was a sesquiterpene with a rare carbon skeleton. The structures of these compounds were determined by extensive NMR studies, including DEPT, COSY, NOE, HMQC, and HMBC.     

A novel gene, BENI is required for the convergent extension during Xenopus laevis gastrulation

Activin-like signaling plays an important role in early embryogenesis. Activin A, a TGF-beta family protein, induces mesodermal/endodermal tissues in animal cap assays. In a screen for genes expressed early after treatment with activin A, we isolated a novel gene, denoted as BENI (Brachyury Expression Nuclear Inhibitor). The BENI protein has a conserved domain at the N-terminus that contains a nuclear localization signal (NLS), and two other NLSs in the C-terminal domain. BENI mRNA was localized to the animal hemisphere at the gastrula stages and to ectoderm except for neural regions at stage 17; expression persisted until the tadpole stage. The overexpression of BENI caused gastrulation defects and inhibition of elongation of activin-treated animal caps with reduction of Xbra expression. Moreover, whole-mount in situ hybridization revealed reduced expression of Xbra in BENI mRNA-injected regions of gastrula embryos. Functional knockdown of BENI using an antisense morpholino oligonucleotide also resulted in an abnormal phenotype of embryos curling to the dorsal side, and excessive elongation of activin-treated animal caps without altered expression of mesodermal markers. These results suggested that BENI expression is regulated by activin-like signaling, and that this regulation is crucial for Xbra expression.     

An amorphane sesquiterpene and a benzofuran glucoside from Eupatorium coelestinum

A phytochemical investigation of the aerial parts of Eupatorium coelestinum led to the isolation of an amorphane sesquiterpene and a benzofuran glucoside. By means of spectroscopic methods, their structures were determined as 5α,8α-epoxy-4α,6β-dihydroxyamorphan-2-one (1) and 2R*,3S*-toxol-7-O-β-d-glucopyranoside (2). Compounds 1 significantly inhibited NF-κB activity in TNF-α-stimulated HeLa cells with the IC₅₀ of 12.4 μM.     

A new semiterpenoid glycoside and a new benzofuran derivative glycoside from the roots of Heracleum dissectum

A new semiterpenoid glycoside, 3-methylbutan-1, 3-diol-1-O-β-d-glucopyranoside (1) and a new benzofuran derivative glycoside, 6-carboxylethyl-benzofuran-5-O-β-d-xylopyranosyl-(1 → 2)-β-d-glucopyranoside (2), together with seven known compounds (3-9) were isolated from the roots of Heracleum dissectum Ledeb. Their structures were elucidated on the basis of physicochemical properties and the detailed interpretation of various spectroscopic data. All the isolated compounds were screened for anti-inflammatory activity in vitro. And the result showed that compound 2 exhibited significantly inhibitory activity on nitric oxide production in RAW264.7 cells, which IC₅₀ value was equivalent to that of the positive control indomethacin.     

Fluorescent labeling of endothelial cells allows in vivo,continuous characterization of the vascular development of Xenopus laevis

Appropriate blood supply and vascular development are necessary in development and in cancer, heart disease, and diabetes. Here, we report the use of DiI-labeled acetylated low-density lipoprotein (DiI-Ac-LDL) to label endothelial cells and characterize the vasculature of live Xenopus embryos. The atlas we have created provides a detailed map of normal vascular development against which perturbations of normal patterning can be compared. By following the development of the intersomitic vessels in real-time, we show that, while rostrocaudal gradient of maturing intersomitic vessels occurs, it is not absolute. In addition, the comparative study of the ontogeny of nerve bundles from the spinal cord of transgenic Xenopus embryos expressing green fluorescent protein in the nervous system and blood vessels demonstrates a strong anatomical correlation in neurovascular development. These studies provide the basis for understanding how the vascular system forms and assumes its complicated stereotypical pattern in normal development and in disease.     

Endocannabinoid system in Xenopus laevis development: CB1 receptor dynamics

This study investigates for the first time the dynamics of endocannabinoid system appearance during low vertebrate Xenopus laevis development. We observed that the CB1 gene started to be expressed during the organogenesis period (+/- 1 dpf, st. 28) and expression persisted throughout the three further stages analyzed. Attention was focused on the localization of the CB1 messenger that was found both at the central level (in romboencephalon and in olfactory placods) and at the peripheral level (in the gastrointestinal tract) at +/- 3 dpf (st. 41), +/- 4 dpf (st. 46) and +/- 12 dpf (st. 49). We also considered the synthesis of CB1 protein that occurred from st. 41 onwards and, from this stage, we tested the receptor functionality in response to anandamide using cytosensor microphysiometry. CB1 functionality increased with development at both central and peripheral level. These data provide sufficient evidence to encourage further analysis on endocannabinoid physiological roles during embryonic and larval X. laevis growth.     

Hypoglycemic activities of A- and B-type procyanidin oligomer-rich extracts from different Cinnamon barks

Procyanidin oligomers in Cinnamon are thought to be responsible for the biological activity in the treatment of diabetes mellitus (DM). To clarify types of procyanidin oligomers in different Cinnamon species and investigate their different effects, the present study investigated procyanidin oligomers in polyphenolic oligomer-rich extracts of three Cinnamon samples by LC-MS methods, and their hypoglycemic activities were detected in vivo and in vitro. The results showed that two of the three samples from Cinnamomum cassia were rich in B-type procyanidin oligomers, and the other sample was rich in A-type procyanidin oligomers. The Cinnamon extracts were administered at doses of 200 and 300 mg/kg body wt. in high-fat diet-fed and low-dose streptozotocin (STZ)-induced diabetic mice for 14 days. The results showed that blood glucose concentrations were significantly decreased in all Cinnamon extract groups compared with the control group (p < 0.05). Administration of the Cinnamon extracts significantly increased the consumption of extracellular glucose in insulin-resistant HepG2 cells and normal HepG2 cells compared with the control group. These results suggest that both A- and B-type procyanidin oligomers in different Cinnamon species have hypoglycemic activities and may improve insulin sensitivity in type 2 DM.     

Production potential of eicosapentaenoic acid by the diatom Nitzschia laevis

To investigate the production potential of eicosapentaenoic acid (EPA) by the diatom Nitzschia laevis, the growth characteristics and fatty acid composition of the cells were studied under photoautotrophic, mixotrophic and heterotrophic conditions of growth. The specific growth rate and maximum biomass concentration were respectively 0.466 d^–1 and 2.27 g l^–1 for mixotrophic culture, 0.344 d^–1 and 2.04 g l^–1 for heterotrophic culture, and 0.167 d^–1 and 0.5 g l^–1 for photoautotrophic culture, respectively. As for EPA production, the yield and productivity were respectively 52.32 mg l^–1 and 10.46 mg l^–1 d for mixotrophic culture, 35.08 mg l^–1 and 6.37 mg l^–1 d for heterotrophic culture, and 6.78 mg l^–1 and 3.39 mg l^–1 d for photoautotrophic culture, respectively. Results suggest that mixotrophic culture is the most suitable growth mode for the production of EPA by the diatom Nitzschia laevis. The results are useful for the development of a cost-effective fermentation process for EPA production by Nitzschia laevis.     

Some effects of the venom of the Chilean spider Latrodectus mactans on endogenous ion-currents of Xenopus laevis oocytes

A study was made of the effects of the venom of the Chilean spider Latrodectus mactans on endogenous ion-currents of Xenopus laevis oocytes. 1 μg/ml of the venom made the resting plasma membrane potential more negative in cells voltage-clamped at −60 mV. The effect was potentially due to the closure of one or several conductances that were investigated further. Thus, we determined the effects of the venom on the following endogenous ionic-currents: (a) voltage-activated potassium currents, (b) voltage-activated chloride-currents, and (c) calcium-dependent chloride-currents (Tout). The results suggest that the venom exerts its action mainly on a transient outward potassium-current that is probably mediated by a Kv channel homologous to shaker. Consistent with the electrophysiological evidence we detected the expression of the mRNA coding for xKv1.1 in the oocytes.     

Hermes is a localized factor regulating cleavage of vegetal blastomeres in Xenopus laevis

We have identified the RNA-binding protein Hermes in a screen for vegetally localized RNAs in Xenopus oocytes. The RNA localizes to the vegetal cortex through both the message transport organizer (METRO) and late pathways. Hermes mRNA and protein are both detected at the vegetal cortex of the oocyte; however, the protein is degraded within a several hour period during oocyte maturation. Injection of antisense morpholino oligonucleotides (HE-MO) against Hermes caused a precocious reduction in Hermes protein present during maturation and resulted in a phenotype characterized by cleavage defects in vegetal blastomeres. The phenotype can be partially rescued by injecting Hermes mRNA. These results demonstrate that the localized RNA-binding protein Hermes functions during oocyte maturation to regulate the cleavage of specific vegetally derived cell lineages. Hermes most likely performs its function by regulating the translation or processing of one or more target RNAs. This is an important mechanism by which the embryo can generate unique cell lineages. The regulation of region-specific cell division is a novel function for a localized mRNA.