Synthesis, characterization, and biological activity of selenium nanoparticles conjugated with polysaccharides.

Nanoparticles with unique properties have potential applications in food, medicine, pharmacology, and agriculture industries. Accordingly, many significant researches have been conducted to develop novel nanoparticles using chemical and biological techniques. This review focuses on the synthesis of selenium nanoparticles (SeNPs) using polysaccharides as templates. Various instrumental techniques being used to confirm the formation of polysaccharide-SeNPs conjugates and characterize the properties of nanoparticles are also introduced. Finally, the biological activities of the synthesized SeNPs and the influence of structural factors of polysaccharides on the property of synthetic nanocomposites are highlighted. In general, the polysaccharides functionalized SeNPs can be easily obtained using sodium selenite as precursor and ascorbic acid as reductant. The final products having different particle size, morphology, and selenium content exhibit abundant physiological activities. Structural factors of polysacchairdes involving molecular weights, substitution of functional groups, and chain conformation play determinant roles on the properties of nanocomposites, resulting in different biological performances. The review on the achievements and current status of polysaccharides conjugated SeNPs provides insights into this exciting research topic for further studies in the future.

Citrinin derivatives from the marine-derived fungus Penicillium citrinum.

Three new citrinin derivatives, penicitrinols C, D, and E (1-3), along with two known compounds, citrinin (4) and decarboxydihydrocitrinone (5), were isolated from Penicillium citrinum. Their structures were determined by spectroscopic methods and X-ray diffraction analysis. Compounds 1 and 3 demonstrated weak cytotoxicity against the HL-60 cell line.

Purification and characterization of gelatinase-like proteinases from the dark muscle of common carp (Cyprinus carpio).

Gelatinolytic proteinases from common carp dark muscle were purified by 30-60% ammonium sulfate fractionation and a combination of chromatographic steps including ion exchange on DEAE-Sephacel, gel filtration on Sephacryl S-200, ion exchange on High-Q, and affinity on gelatin-Sepharose. The molecular masses of these proteinases as estimated by SDS-PAGE were 75, 67, and 64 kDa under nonreducing conditions. The enzymes revealed high activity at a slightly alkaline pH range, and their activities were investigated using gelatin as substrate. Metalloproteinase inhibitors, EDTA, EGTA, and 1,10-phenanthroline, almost completely suppressed the gelatinolytic activity, whereas other proteinase inhibitors did not show any inhibitory effect. Divalent metal ion Ca (2+) is essential for the gelatinolytic activity. Furthermore, these gelatinolytic proteinases hydrolyze native type I collagen effectively even at 4 degrees C, strongly suggesting their involvement in the texture softening of fish muscle during the post-mortem stage.

Identification of an adaptor protein that facilitates Nrf2-Keap1 complex formation and modulates antioxidant response.

Nrf2 plays a key role in the protection of the body against environmental stress via inducible expression of detoxification and antioxidant enzymes. Keap1 functions as a sensor for oxidative and electrophilic stresses and promotes Nrf2 degradation via its E3 ligase activity. Modulation of the Nrf2-Keap1 pathway has been extensively explored as a strategy to combat against drug toxicity and stress-induced diseases. Here we report a new player that modulates the Nrf2-Keap1 pathway. PAQR3, a membrane protein specifically localized in the Golgi apparatus, negatively regulates the expression of an array of Nrf2 target genes and alters cellular level of reactive oxygen species. PAQR3 tethers Nrf2 and Keap1, but not small MAF proteins to the Golgi apparatus. PAQR3 interacts with both Nrf2 and Keap1 and facilitates the interaction of Nrf2 with Keap1. PAQR3 promotes ubiquitination and degradation of Nrf2. Disruption of PAQR3 interaction with Nrf2 and Keap1 by a synthetic peptide reduces Nrf2 ubiquitination and elevates expression of Nrf2 target genes. At the animal level, deletion of PAQR3 increases Nrf2 protein level and the expression of Nrf2 target genes. In conclusion, our study pinpoints that PAQR3 functions as an adaptor protein to promote Nrf2-Keap1 complex formation, thereby modulating the Nrf2-Keap2 pathway and playing an important role in controlling antioxidant response of the cell.

Heparan Sulfate Biosynthesis Enzyme, Ext1, Contributes to Outflow Tract Development of Mouse Heart via Modulation of FGF Signaling.

Glycosaminoglycans are important regulators of multiple signaling pathways. As a major constituent of the heart extracellular matrix, glycosaminoglycans are implicated in cardiac morphogenesis through interactions with different signaling morphogens. Ext1 is a glycosyltransferase responsible for heparan sulfate synthesis. Here, we evaluate the function of Ext1 in heart development by analyzing Ext1 hypomorphic mutant and conditional knockout mice. Outflow tract alignment is sensitive to the dosage of Ext1. Deletion of Ext1 in the mesoderm induces a cardiac phenotype similar to that of a mutant with conditional deletion of UDP-glucose dehydrogenase, a key enzyme responsible for synthesis of all glycosaminoglycans. The outflow tract defect in conditional Ext1 knockout(Ext1f/f:Mesp1Cre) mice is attributable to the reduced contribution of second heart field and neural crest cells. Ext1 deletion leads to downregulation of FGF signaling in the pharyngeal mesoderm. Exogenous FGF8 ameliorates the defects in the outflow tract and pharyngeal explants. In addition, Ext1 expression in second heart field and neural crest cells is required for outflow tract remodeling. Our results collectively indicate that Ext1 is crucial for outflow tract formation in distinct progenitor cells, and heparan sulfate modulates FGF signaling during early heart development.

Purification and characterization of a gelatinolytic matrix metalloproteinase from the skeletal muscle of grass carp (Ctenopharyngodon idellus).

A gelatinolytic matrix metalloproteinase (gMMP) from grass carp skeletal muscle was purified by 30-70% ammonium sulphate fractionation and a combination of chromatographic steps including ion exchange on DEAE-Sephacel, gel filtration on Sephacryl S-200, and affinity on gelatin-sepharose. The molecular weight of the proteinase as estimated by SDS-PAGE was 70 kDa under non-reducing conditions. The enzyme revealed high activity from 30 to 50 °C, and the gelatin hydrolysing activity was investigated at a slightly alkaline pH range using gelatin as substrate. Metalloproteinase inhibitor EDTA completely suppressed the gelatinolytic activity, while other proteinase inhibitors did not show any inhibitory effect. Divalent metal ion Ca(2+) was essential for the gelatinolytic activity. Further, peptide mass fingerprinting obtained four fragments with 45 amino acid residues, which were highly identical to MMP-2 from fish species. The gMMP could effectively hydrolyse type I collagen even at 4 °C, suggesting its involvement in the texture softening of fish muscle during the post-mortem stage.