Evaluation of bioactivity of fucoidan from laminaria with in vitro human cell cultures (THP-1)

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked FilesBackground: Seaweeds represent one of the few remaining food sources available globally which are not being fully utilized or even over utilized. Kelps (Laminaria spp.) are one of the numerous species of brown seaweeds, a popular marine vegetable, which has been used as a source of iodine and minerals for centuries. Kelps contain anionic polysaccharides called fucoidans heteroglycans with L-fucose units. Their monosaccharide composition, physicochemical and bioactive properties vary between seaweed species. The objective of this work was to evaluate the bioactive properties of laminaria fucoidan (L. digitata and L. hyperborea) toward THP-1 macrophages, a human macrophage like cell line, and investigate its potential antioxidant and immunomodulatory characteristics. Methods: THP-1 macrophages were incubated with five fucoidan concentrations. The Oxygen Radical Absorbance Capacity (ORAC) assay was determined for cell lysates and for the fucoidan extract, in addition to Total Polyphenol Content (TPC). Cytotoxicity of fucoidan was assessed by light microscopy, followed by XTT proliferation assay. Enzyme-linked immunosorbant assays (ELISA) were performed to determine concentrations of the secreted tumor necrosis factor a (TNF-a), interleukin 6 (IL-6), and interleukin 10 (IL-10). Results: Fucoidan did not affect macrophage ability to scavenge oxygen radicals (ORAC) confirming its antioxidant properties toward activated macrophages. The laminaria fucoidan extract at 100 mu g/ml concentration lowered macrophage viability. Lower concentrations of laminaria fucoidan did not have impact on cell viability. Very low concentration of fucoidan at 0.1 mu g/ml triggered secretion of TNF-alpha. However, IL-6 and interleukin IL-10 were expressed when concentration of applied fucoidan was 10 mu g/ml indicating bioactivity of laminaria fucoidan through immunomodulatory actions. Conclusions: The study demonstrated how laminaria fucoidan may have bioactive properties towards THP-1 macrophages. Changes in cytokine secretion between pro-inflammatory (TNF-alpha, and IL-6) and anti-inflammatory (IL-10) cytokines confirmed bioactivity of the laminaria fucoidan extracts.University of Iceland Research Fun

Characterization of Volatile Compounds in Chilled Cod (Gadus morhua) fillets by gas chromatography and detection of quality indicators by an electronic nose

Volatile compounds in cod fillets packed in Styrofoam boxes were analyzed during chilled storage (0.5 C) by gas chromatography (GC)-mass spectrometry and GC-olfactometry to screen potential quality indicators present in concentrations high enough for detection by an electronic nose. Photobacterium phosphoreum dominated the spoilage bacteria on day 12 when the fillets were rejected by sensory analysis. Ketones, mainly 3-hydroxy-2-butanone, were detected in the highest level (33%) at sensory rejection, followed by amines (TMA) (29%), alcohols (15%), acids (4%), aldehydes (3%), and a low level of esters

Influence of Molecular Character of Chitosan on the Adsorption of Chitosan to Oil Droplet Interfaces in an in Vitro Digestion Model

The relationship between the adsorption of chitosan to oil droplet interfaces (surface adsorption) and the molecular characteristics of the chitosan (molecular weight and charge density) was examined using an in vitro digestion model. This model involved adding different concentrations (3–10 wt%) of oil droplets to a 0.1 wt% chitosan solution at pH 3 to simulate consumption of an oil-containing meal after ingestion of chitosan. The pH was then incrementally raised to investigate pH variations that occur when a food material passes through the human digestive tract at an oil concentration of 3%. The amount of chitosan adsorbed to the oil droplet interface decreased with decreasing molecular weight (MW) and with increasing degree of deacetylation (DDA): ≈132, 85, and 78 g of oil per g of chitosan for MWs of 200, 500 and 750 kDa (all 90% DDA), respectively; and, 47, 65, and 78 g of oil per g of chitosan for DDAs of 40%, 70% and 90% (all 750 kDa), respectively at pH 3. In addition, the extent of droplet aggregation and the nature of the aggregates formed (strong versus weak; large versus small) also depended on chitosan characteristics. The pH dependence of the interaction between anionic oil droplets and cationic chitosan molecules depended on both MW and DDA. Microscope images showed formation of large flocculated structures at pH \u3e 7 except for low DDA chitosan which remained soluble at all pH levels. Our results may have important consequences for understanding the bioactivity of chitosan, and for designing functional food ingredients to reduce lipid digestion and absorption

Effect of Surfactant Surface Coverage on Formation of Solid Lipid Nanoparticles (SLN)

The effect of surfactant surface coverage on formation and stability of Tween 20 stabilized tripalmitin solid lipid nanoparticles (SLN) was investigated. A lipid phase (10% w/w tripalmitin) and an aqueous phase (2% w/w Tween 20, 10 mM phosphate buffer, pH 7) were heated to 75 degrees C and then homogenized using a microfluidizer. The resulting oil-in-water emulsion was kept at a temperature (37 degrees C) above the crystallization temperature of the tripalmitin to prevent solidification of emulsion droplets, and additional surfactant at various concentrations (0-5% w/w Tween 20) was added. Droplets were then cooled to 5 degrees C to initiate crystallization and stored at 20 degrees C for 24 h. Particle size and/or aggregation were examined visually and by light scattering, and crystallization behavior was examined by differential scanning calorimetry (DSC). Excess Tween 20 concentration remaining in the aqueous phase was measured by surface tensiometry. Emulsion droplets after homogenization had a mean particle diameter of 134.1+/-2.0 nm and a polydispersity index of 0.08+/-0.01. After cooling to 5 degrees C at low Tween 20 concentrations, SLN dispersions rapidly gelled due to aggregation of particles driven by hydrophobic attraction between insufficiently covered lipid crystal surfaces. Upon addition of 1-5% w/w Tween 20, SLN dispersions became increasingly stable. At low added Tween 20 concentration (\u3c1% w/w) the SLN formed gels but only increased slightly at higher surfactant concentrations (\u3e1% w/w). The Tween 20 concentration in the aqueous phase decreased after tripalmitin crystallization suggesting additional surfactant adsorption onto solid surfaces. At higher Tween 20 concentrations, SLN had increasingly complex crystal structures as evidenced by the appearance of additional thermal transition peaks in the DSC. The results suggest that surfactant coverage at the interface may influence crystal structure and stability of solid lipid nanoparticles via surface-mediated crystal growth

Influence of Polymorphic Transformations on Gelation of Tripalmitin Solid Lipid Nanoparticle Suspensions

Solid lipid nanoparticle (SLN) suspensions, which consist of submicron-sized crystalline lipid particles dispersed within an aqueous medium, can be used to encapsulate, protect and deliver lipophilic functional components. Nevertheless, SLN suspensions are susceptible to particle aggregation and gelation during their preparation and storage, which potentially limits their industrial utilization. In this study, we examined the aggregation and gelation behavior of SLN suspensions composed of 10 wt% tripalmitin particles (r \u3c 150 nm) stabilized by 1.5% Tween 20. The tripalmitin and aqueous surfactant solution were homogenized above the lipid melting temperature and cooled under controlled conditions to initiate SLN formation. The aggregation and gelation of SLN suspensions during storage was then examined by shear rheometry, differential scanning calorimetry (DSC), light scattering and microscopy. Rheology measurements indicated that gelation times decreased with increasing storage temperature, e.g., samples formed weak gels after 62, 23, and 10 min at 1, 5, and 10 °C, respectively. DSC revealed increasingly rapid α- to β-polymorphic transformations in SLN dispersions stored at 1, 5, and 10 °C, respectively. We propose that the observed aggregation and gelation of SLN suspensions are associated with a change in the shape of the nanoparticles from spherical (α-form) to non-spherical (β-form) when they undergo the polymorphic transition. When they change shape there is no longer sufficient surfactant present to completely cover the lipid phase, which promotes particle aggregation through hydrophobic attraction. Our results have important implications for the design and fabrication of stable SLN suspensions

Effect of cooling and heating rates on polymorphic transformations and gelation of tripalmitin solid lipid nanoparticle (SLN) suspensions

Solid lipid nanoparticle (SLN) suspensions undergo a phase transition from the α- to β-polymorphic forms, which is accompanied by particle aggregation and gel formation. These processes are both time and temperature dependent, and so it is important to study the impact of cooling rates (CRs) and heating rates (HRs) on polymorphic transformations, particle aggregation, and gelation. Rheology measurements indicated that the temperature where gelation was first observed during cooling (T gel) decreased with increasing CRs, with SLN suspensions remaining fluid at HR ≥ 5 °C/min. On the other hand, the temperature where gelation was first observed during heating of stable SLN suspensions increased with increasing HRs: 18, 24, 31, and 45 °C at 2, 5, 10, and 20 °C/min, respectively. When the melted SLN suspensions were cooled again, two exothermic peaks were observed in the differential scanning calorimetry scans at 39 (which was attributed to coalesced oil) and 19 °C (which was attributed to stable SLN). With increasing CR, the enthalpy of the coalescence peak (ΔH CO) decreased, while that of the supercooled SLN (ΔH SLN) increased. With increasing HR, ΔH CO decreased and ΔH SLN increased, with no coalescence being observed at HR ≥ 10 °C/min. These results show that increasing the CRs or HRs retard the α→β polymorphic transformation, which increased the stability of SLN against aggregation and retarded gelation. In addition, this study shows that the careful selection of HRs and CRs is required to examine polymorphic transformations and the stability of SLN suspensions