β-Glucan extracts inhibit the in vitro intestinal uptake of long-chain fatty acids and cholesterol and down-regulate genes involved in lipogenesis and lipid transport in rats

BackgroundDietary fiber reduces the intestinal absorption of nutrients and the blood concentrations of cholesterol and triglycerides.AimWe wished to test the hypothesis that high-viscosity (HV) and low-viscosity preparations of barley and oat β-glucan modify the expression of selected genes of lipid-binding proteins in the intestinal mucosa and reduce the intestinal in vitro uptake of lipids.MethodsFive different β-glucan extracts were separately added to test solutions at concentrations of 0.1–0.5% (wt/wt), and the in vitro intestinal uptake of lipids into the intestine of rats was assessed. An intestinal cell line was used to determine the effect of β-glucan extracts on the expression of intestinal genes involved in lipid metabolism and fatty acid transport.ResultsAll extracts reduced the uptake of 18:2 when the effective resistance of the unstirred water layer was high. When the unstirred layer resistance was low, the HV oat β-glucan extract reduced jejunal 18:2 uptake, while most extracts reduced ileal 18:2 uptake. Ileal 18:0 uptake was reduced by the HV barley extract, while both jejunal and ileal cholesterol uptakes were reduced by the medium-purity HV barley extract. The inhibitory effect of HV barley β-glucan on 18:0 and 18:2 uptake was more pronounced at higher fatty acid concentrations. The expression of genes involved in fatty acid synthesis and cholesterol metabolism was down-regulated with the HV β-glucan extracts. β-Glucan extracts also reduced intestinal fatty-acid-binding protein and fatty acid transport protein 4 mRNA.ConclusionsThe reduced intestinal fatty acid uptake observed with β-glucan is associated with inhibition of genes regulating intestinal uptake and synthesis of lipids. The inhibitory effect of β-glucan on intestinal lipid uptake raises the possibility of their selective use to reduce their intestinal absorption.     

Evaluation of biomolecular interactions of sulfated polysaccharide isolated from Grateloupia filicina on blood coagulation factors

An edible marine red alga, Grateloupia filicina, collected from Jeju Island of Korea was hydrolyzed by cheap food-grade carbohydrases (Viscozyme, Celluclast, AMG, Termamyl, and Ultraflo) to investigate its anticoagulant activity. Among the tested enzymatic extracts of G. filicina, a Termamyl extract showed the highest anticoagulant activity. Anion-exchange chromatography on DEAE-cellulose and gelpermeation chromatography on Sepharose-4B were used to purify the active polysaccharide from the crude polysaccharide fraction of G. filicina. The purified sulfated polysaccharide (0.42 sulfate/total sugar) showed approximately 1,357 kDa molecular mass and was comprised mainly of galactose (98%) and 1-2% of glucose. The sample showed potential anticoagulant activity on activated partial thromboplastin time (APTT) and thrombin time (TT) assays. The purified G. filicina anticoagulant (GFA) inhibited the coagulation factor X (92%), factor II (82%), and factor VII (68%) of the coagulation cascade, and the molecular interaction (protein-polysaccharide) was highly enhanced in the presence of ATIII (antithrombin III). The dissociation constant of polysaccharide towards serine proteins decreased in the order of FXa (58.9 nM) >FIIa (74.6 nM) >FVII (109.3 nM). The low/less cytotoxicity of the polysaccharide benefits its use in the pharmaceutical industry; however, further studies that would help us to elucidate the mechanism of its activity are needed.     

Tannase activity from the marine cyanobacterium Phormidium valderianum BDU140441

The marine cyanobacterium Phormidium valderianum BDU 140441 exhibited the ability to grow at 0.25?mM tannic acid, a known hindering chemical for microbial growth. The tannic acid-degrading ability of the organism is evident from the UV–visible absorption spectrum. In addition, the existence of tannase has been localized by activity staining, and its induction in activity upon tannic acid exposure was confirmed in native gel. The critical tannic acid metabolization enzymes tested for are polyphenol oxidase and esterases; both are well known for tannic acid degradation. Upon tannic acid exposure, increased activity of polyphenol oxidase and expression of few new isoforms of esterase were identified by activity staining.     

Structure prediction of Bestrophin for the induced - fit docking of anthocyanins

Bestrophin, an integral membrane protein existing in basolateral region of the retina is a propitious target for drug discovery. Mutations in the Bestrophin protein cause Best Vitelliform Macular Dystrophy (BVMD) leading to retinal damages and loss of visual acuity. Owing to the lack of three dimensional structure and related structural homologs in the protein data bank, we modeled the bestrophin protein using Robetta ab initio method. Further, no treatment is available for the disease. In this situation, anthocyanins from natural sources are reported to combat retinal damages. Hence, we identified anthocyanins from Syzygium cumini fruit skin using Electrospray Ionization tandem mass spectrometry. These compounds were docked into the predicted bestrophin model to study the interactions within the active site. The results may provide a valuable insight into the structure of bestrophin and efficacy of anthocyanins in molecular docking studies.

Abbreviations

PTP - Putative transmembrane proteins, VMD - Vitelliform macular dystrophy, BVMD - Best''s vitelliform macular dystrophy, RPE - Retinal pigment epithelium, ESI-MS/MS - Electrospray Ionization Tandem Mass Spectrometry, UNIPROT - Universal Protein Resource, PSIPRED - Protein secondary structure prediction, TMH - Transmembrane Helices, SCFS - Syzygium cumini fruit skin DP - Declustering Potential IFD - Induced Fit Docking.     

Nanoplastics alter ecosystem multifunctionality and may increase global warming potential

Although the presence of nanoplastics in aquatic and terrestrial ecosystems has received increasing attention, little is known about its potential effect on ecosystem processes and functions. Here, we evaluated if differentially charged polystyrene (PS) nanoplastics (PS-NH₂ and PS-SO₃H) exhibit distinct influences on microbial community structure, nitrogen removal processes (denitrification and anammox), emissions of greenhouse gases (CO₂, CH₄, and N₂O), and ecosystem multifunctionality in soils with and without earthworms through a 42-day microcosm experiment. Our results indicated that nanoplastics significantly altered soil microbial community structure and potential functions, with more pronounced effects for positively charged PS-NH₂ than for negatively charged PS-SO₃H. Ecologically relevant concentration (3 g kg⁻¹) of nanoplastics inhibited both soil denitrification and anammox rates, while environmentally realistic concentration (0.3 g kg⁻¹) of nanoplastics decreased the denitrification rate and enhanced the anammox rate. The soil N₂O flux was always inhibited 6%–51% by both types of nanoplastics, whereas emissions of CO₂ and CH₄ were enhanced by nanoplastics in most cases. Significantly, although N₂O emissions were decreased by nanoplastics, the global warming potential of total greenhouse gases was increased 21%–75% by nanoplastics in soils without earthworms. Moreover, ecosystem multifunctionality was increased 4%–12% by 0.3 g kg⁻¹ of nanoplastics but decreased 4%–11% by 3 g kg⁻¹ of nanoplastics. Our findings provide the only evidence to date that the rapid increase in nanoplastics is altering not only ecosystem structure and processes but also ecosystem multifunctionality, and it may increase the emission of CO₂ and CH₄ and their global warming potential to some extent.     

Sulfated polysaccharide purified from <Emphasis Type="BoldItalic">Ecklonia cava</Emphasis> accelerates antithrombin III-mediated plasma proteinase inhibition

Surface plasmon resonance is an important technique for studying molecular interactions and was used to investigate the molecular interaction of anticoagulant sulfated polysaccharides purified from an enzymatic hydrolysate of the brown alga Ecklonia cava (ECA) with blood coagulation factors. In a direct binding assay, binding affinity between ECA/antithrombin III (ATIII) and activated blood coagulation factors was in the order: factor VIIa (FVIIa) > factor Xa (FXa) > thrombin (FIIa); kinetic analysis determined K _D values of ECA for FVIIa, FXa, and FIIa of 15.1, 45.0 and 65.0 nM, respectively. Therefore, ECA strongly and selectively (FVII, FX, and FII) enhanced ATIII-mediated coagulation factor inhibition in both the extrinsic and common coagulation pathways. This may contribute to its high anticoagulant activity in vitro. The low cytotoxicity of ECA to venous endothelial cell line (ECV-304) also expands its value in future in vivo studies. However, to utilize it as a model for novel anticoagulant agents, its possible interference with other anticoagulant mechanisms must be addressed.     

Synthesis, spectral characterization, and single crystal X-ray structures of a series of manganese-2,2′-bipyridine complexes derived from substituted aromatic carboxylic acids

Reaction of [Mn(2,2′-bpy)₂(OAc)](ClO₄)(H₂O) with a series of aromatic carboxylic acids yields new Mn(II)carboxylates [Mn(2,2′-bpy)₂(L)](ClO₄)}₂ (1-3), [Mn(2,2′-bpy)₂(L)₂] (4-5) and [Mn(2,2′-bpy)₂(L)(H₂O)](ClO₄) (6) (L = 2-aminobenzoate (2-aba) (1), 4-hydroxybenzoate (4-hba) (2), thiophene-2-carboxylate (2-tca) (3), 2-hydroxynapthoate (2-hnapa) (4), 3,5-diisopropylsalicylic acid (dipsa) (5), 2,4,6-triisopropylbenzoate (tipba) (6)). The new compounds have been characterized with the aid of elemental analysis, spectroscopy, and single-crystal X-ray diffraction studies. Compounds 1-3, which have been synthesized from less bulky carboxylic acids, are dimeric in the solid-state. Compounds 4-6, which are derived from more bulkier aromaric carboxylic acids, exist as monomeric complexes. In the case of 6, where very bulky 2,4,6-triisopropyl benzoic acid is used as the starting material, only one carboxylate ligand binds to the metal, resulting in a cationic complex. Interestingly in all the six complexes, the C-H hydrogen atoms of the 2,2′-bpy ligands are involved in extensive hydrogen bonding with the carboxylate oxygen atoms of the adjacent molecules and hence form non-covalent 1-D or 2-D aggregates in the solid state.     

Microbial diversity and hydrocarbon degrading gene capacity of a crude oil field soil as determined by metagenomics analysis

Soils contaminated with crude oil are rich sources of enzymes suitable for both degradation of hydrocarbons through bioremediation processes and improvement of crude oil during its refining steps. Due to the long term selection, crude oil fields are unique environments for the identification of microorganisms with the ability to produce these enzymes. In this metagenomic study, based on Hiseq Illumina sequencing of samples obtained from a crude oil field and analysis of data on MG‐RAST, Actinomycetales (9.8%) were found to be the dominant microorganisms, followed by Rhizobiales (3.3%). Furthermore, several functional genes were found in this study, mostly belong to Actinobacteria (12.35%), which have a role in the metabolism of aliphatic and aromatic hydrocarbons (2.51%), desulfurization (0.03%), element shortage (5.6%), and resistance to heavy metals (1.1%). This information will be useful for assisting in the application of microorganisms in the removal of hydrocarbon contamination and/or for improving the quality of crude oil. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:638–648, 2016     

Toxicity and bioaccumulation of iron in soil microalgae

Microalgae are extensively used in the remediation of heavy metals like iron. However, factors like toxicity, bioavailability and iron speciation play a major role in its removal by microalgae. Thus, in this study, toxicity of three different iron salts (FeSO₄, FeCl₃ and Fe(NO₃)₃) was evaluated towards three soil microalgal isolates, Chlorella sp. MM3, Chlamydomonas sp. MM7 and Chlorococcum sp. MM11. Interestingly, all the three iron salts gave different EC50 concentrations; however, ferric nitrate was found to be significantly more toxic followed by ferrous sulphate and ferric chloride. The EC₅₀ analysis revealed that Chlorella sp. was significantly resistant to iron compared to other microalgae. However, almost 900 μg g^?1 iron was accumulated by Chlamydomonas sp. grown with 12 mg L^?1 ferric nitrate as an iron source when compared to other algae and iron salts. The time-course bioaccumulation confirmed that all the three microalgae adsorb the ferric salts such as ferric nitrate and ferric chloride more rapidly than ferrous salt, whereas intracellular accumulation was found to be rapid for ferrous salts. However, the amount of iron accumulated or adsorbed by algae, irrespective of species, from ferrous sulphate medium is comparatively lower than ferric chloride and ferric nitrate medium. The Fourier transform infrared spectroscopy (FTIR) analysis shows that the oxygen atom and P?=?O group of polysaccharides present in the cell wall of algae played a major role in the bioaccumulation of iron ions by algae.