Natural products and insulin signalling

PTP1B ist eine intrazelluläre Phosphatase, die als negativer Regulator des Insulin- und des Leptin-Signalweges identifiziert wurde. Studien belegen, dass PTP1B-knock-out Mäuse eine erhöhte Insulin-Sensitivität aufweisen und zusätzlich über einen Schutz vor Fettleibigkeit verfügen. Aufgrund dieser Eigenschaften wurde PTP1B ein „molecular target“ in der Entwicklung neuer Therapeutika zur Behandlung des metabolischen Syndroms und Typ 2 Diabetes. Fünf verschiedene Pflanzen (Averrhoa bilimbi, Agrimonia pilosa, Arisaema amurense, Phellodendron amurensae und Leonorus sibiricus) und ein Apfelsaft für Extraktionen ausgewählt. Die Extrakte wurden in vitro auf ihr PTP1B-inhibierendes Potential mittels Enzym-Assay getestet. Im Falle einer von uns nachgewiesenen Wirksamkeit, wurde eine `bioassay-guided‘-Fraktionierung der Substanz durchgeführt mit dem Ziel eventuelle PTP1B-Inhibitoren natürlichen Ursprungs zu finden. Weiterführend wurden wirksame Substanzen an einem Zellkulturmodel getestet, um die Wirkung zu bestätigen. Alle Pflanzenextrakte außer Leonorus sibiricus zeigten eine vielversprechende PTP1B- Inhibierung. Die aus Phellodendron sp extrahierte Ölsäure zeigte eine starke PTP1B-Inhibierung (IC50 = 4.88 μM). Diese Wirkung wies darauf hin, dass möglicherweise andere Fettsäuren ebenfalls das Enzym PTP1B hemmen könnten. Wir konnten in der Tat zeigen, dass Palmitinsäure (IC50 = 13.40 μM) ebenso wie Linolsäure (IC50 = 18.34 μM) starke PTP1B-Inhibition aufwiesen, wohingegen für Stearinsäure die schwächste Wirksamkeit in der Gruppe der getesteten Fettsäuren nachgewiesen wurde. Weiters konnten wir Procyanidine, eine Gruppe von chemischen Verbindungen in Äpfeln, als potente PTP1B-Inhibitoren (IC50 = 79.08 μg/ml) identifizieren. Darüber hinaus bewirkten mehrere Fraktionen aus Averrhoa bilimbi eine in vitro Inhibierung von PTP1B.PTP1B, an intracellular phosphatase, has been identified as a major negative regulator of insulin and leptin signalling. Since several studies demonstrated that PTP1B knock-out mice showed increased insulin sensitivity and gained protection from obesity, PTP1B has become the focus of interest in finding novel therapeutics in treating metabolic syndrome and type 2 diabetes. Five different plants (Averrhoa bilimbi, Agrimonia pilosa, Arisaema amurense, Phellodendron amurense and Leonorus sibiricus) and one apple juice were chosen for extraction and testing for their PTP1B inhibitory potential in an enzyme-based in vitro assay. The selection was mainly based on the traditional use or reported activities in the context of metabolic disorders. All plant extracts except from Leonorus sibiricus displayed promising PTP1B inhibition. Like this, oleic acid was isolated from Phellodendron sp demonstrating strong PTP1B inhibition (IC50 = 4.88 μM) and indicating that other fatty acids might as well inhibit PTP1B. We could indeed show that palmitic acid (IC50 = 13.40 μM) as well as linoleic acid (IC50 = 18.34 μM) were strong PTP1B inhibitors whereas stearic acid was the least active of the tested fatty acids. Furthermore, procyanidines in apple have been identified as potent PTP1B inhibitors with an IC50 = 79.08 μg/ml. Moreover, several fractions of the Averrhoa bilimbi extract exhibited PTP1B inhibition in vitro and in a cell-based model

First Cold Spraying of Carbonated Biomimetic Nanocrystalline Apatite on Ti6Al4V: Physical-Chemical, Microstructural, and Preliminary Mechanical Characterizations

Carbonated Biomimetic Nanocrystalline Apatite (BNAc) coatings are obtained for the first time by Cold Spray. The coatings are characterized by FTIR, Raman, XRD, and SEM and compared to the powders. No significant chemical and structural changes are detected and the nanostructure features of these very reactive BNAc are preserved in the coating. These results and preliminary mechanical assays show that Cold Spray can produce an operational biomimetic coatings offering a high potential for implants functionalization and osseointegration. However, these first results need further studies in order to understand the mechanism of adhesion and the interactions at the coating–substrate interface

Fabrication and characterisation of cobalt ferrite nanoparticles and SPPS-deposited cobalt ferrite splats prepared by sol-gel methods

Sol-gel techniques offer enhanced control over homogeneity, elemental composition and powder morphology. As well, uniformly nano-sized metal clusters can be achieved, which are crucial for enhancing the properties of the nanoparticles. These advantages make the sol-gel route a favourable alternative to other conventional methods for the preparation of ceramic oxide composites. The aim of this work is to develop novel multifunctional magnetic iron-based nanoparticles. It is intended that these so-formed nanomaterials will demonstrate antibacterial properties to fulfil the requirements of a drug delivery system so that the antibiotic concentration that is normally required may be minimized. For this purpose, cobalt ferrite nanoparticles have been synthesized by the sol-gel process using citric acid (CA) and polyvinyl alcohol (PVA) as chelating agents, and the effect of chelating agents on surface morphology, size distribution and antibacterial properties of the synthesized cobalt ferrite nanoparticles have been investigated. In addition, transition metal-substituted spinel ferrite nanoparticles (X0.5Y0.5Fe2O4 with X = Co, Mg, Mn, Zn; Y = Cu, Zn, Mn, and Ni) have been synthesized by the sol-gel process using citric acid as the chelating agent. The effect of substitution of these transition metals on surface morphology, size distribution, biocompatibility and antibacterial properties of the synthesized transition metals-substituted spinel ferrite nanoparticles have been investigated

Transition metals-substituted cobalt ferrite nanoparticles for biomedical applications

Transition metals of copper, zinc, chromium and nickel were substituted into cobalt ferrite nanoparticles via a sol-gel route using citric acid as a chelating agent. The microstructure and elemental composition were characterized using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. Phase analysis of transition metal-substituted cobalt ferrite nanoparticles was performed via X-ray diffraction. Surface wettability was measured using the water contact angle technique. The surface roughness of all nanoparticles was measured using profilometry. Moreover, thermogravimetric analysis and differential scanning calorimetry were performed to determine the temperature at which the decomposition and oxidation of the chelating agents took place. Results indicated that the substitution of transition metals influences strongly the microstructure, crystal structure and antibacterial property of the cobalt ferrite nanoparticles

Feedstock material considerations for thermal spray

Feedstock materials are an integral part of any coating system that includes the substrate, possibly an intermediate layer, and finally the bulk of the coating. The coating structure is highly oriented with lamellae (also termed as splats) parallel to the substrate surface. The real contact area of lamellae is approximately 30% of the available boundary area. Unmelted particles may become incorporated into the coating, and these, along with interlamellar oxide boundaries and porosity, constitute regions of poor bonding that lead to failure of the coating system. On the other hand, melting of the material does not always indicate good adhesion, because substrate properties and material/substrate interactions are critical. In addition, there is no evidence that the highest deposition efficiency gives rise to the most optimum structure that confers the best adhesion. For example, an extreme case concerns coatings that incorporate nanostructured microstructures, because these must undergo a certain degree of only partial melting in order to retain these desirable nanoartifacts

Anti-bacterial property of Cold-Sprayed ZnO-Al Coating

The antibacterial behaviour of ZnO nanopowder and their composite coatings were investigated against E. Coli. ZnO nanopowder and Aluminum based ZnO composite powders were synthesized using in-house powder processing techniques. Bacteria culture results showed that ZnO nanopowder and their composite powders displayed excellent bacteriostatic activity against E. coli. The antibacterial activity increased with increasing concentration of ZnO nanoparticle in their composite powders as well as increasing surface area of compacted pellets. These nanocomposite powders were subsequently used to generate antibacterial coatings using cold spray technology. The ratio of Al to ZnO in their composite powders were 80:20, 50:50 and 20:80 (wt.%). Microstructural characterization and phase analysis of feedstock powders and as-deposited coatings were carried out using FESEM/EDX and XRD. Antibacterial nanocomposite Al-ZnO coatings were successfully deposited using cold spraying parameters of 15 Bars at air temperature of between 200-300 degrees C. These assprayed coatings of Al-ZnO composite powders with varying Al and ZnO ratios retained their inherent antibacterial property as verified from bacterial counting test. The results indicated that the antibacterial activity increased with increasing ZnO nanopowder concentration in the composite powder feedstock and cold sprayed coating

Multifunctional spinel ferrite nanoparticles for biomedical application

This chapter is organized into six major parts. The first part introduces the synthesis of transition metal-substituted cobalt ferrite nanoparticles, the use of citric acid (CA) as a chelating agent in the sol-gel method, and applications of spinel ferrite nanoparticles in biomedical fields. The second part provides an overview of the structure and magnetism of spinel ferrites. The third part examines the sol-gel synthesis of ceramic nanoparticles. The fourth part presents a summary of organic acid chelating agents, with special reference to CA. The fift h part looks at the preparation of cobalt ferrite and transition metal-substituted cobalt ferrite nanoparticles (Co0.5X0.5Fe2 O4 with X = Cu, Zn, Mn or Ni) by sol-gel methods. The final section highlights the influence of transition metal substitution on the physical and antibacterial properties of cobalt ferrite nanoparticles. A discussion on the biocompatibility of spinel ferrite nanoparticles is presented