Preparation and characterization of controlled-release fertilizers coated with marine polysaccharide derivatives

Encapsulation of water-soluble nitrogen fertilizers by membranes can be used to control the release of nutrients to maximize the fertilization ef fect and reduce environmental pollution.In this research,we formulated a new double-coated controlled-release fertilizer(CRF)by using food-grade microcrystalline wax(MW)and marine polysaccharide derivatives(calcium alginate and chitosan-glutaraldehyde copolymer).The pellets of water-soluble nitrogen fertilizer were coated with the marine polysaccharide derivatives and MW.A convenient and eco-friendly method was used to prepare the CRF.Scanning electron microscopy(SEM)and Fourier transform infrared spectroscopy(FTIR)were used to characterize the morphology and composition of the products.The nitrogen-release properties were determined in water using UV-Vis spectrophotometry.The controlled-release properties of the fertilizer were improved dramatically after coating with MW and the marine polysaccharide derivatives.The results show that the double-coated CRFs can release nitrogen in a controlled manner,have excellent controlled-release features,and meet the European Standard for CRFs.

Inhibition of BACE1, the β-secretase implicated in Alzheimer’s disease, by a chondroitin sulfate extract from Sardina pilchardus

The pharmaceutical and anticoagulant agent heparin,a member of the glycosaminoglycan family of carbohydrates,has previously been identified as a potent inhibitor of a key Alzheimer’s disease drug target,the primary neuronalβ-secretase,β-site amyloid precursor protein cleaving enzyme 1(BACE1).The anticoagulant activity of heparin has,however,precluded the repurposing of this widely used pharmaceutical as an Alzheimer’s disease therapeutic.Here,a glycosaminoglycan extract,composed predominantly of 4-sulfated chondroitin sulfate,has been isolated from Sardina pilchardus,which possess the ability to inhibit BACE1(IC50[half maximal inhibitory concentration]=4.8μg/mL),while displaying highly attenuated anticoagulant activities(activated partial thromboplastin time EC50[median effective concentration]=403.8μg/mL,prothrombin time EC50=1.3 mg/mL).The marine-derived,chondroitin sulfate extract destabilizes BACE1,determined via differential scanning fluorimetry(ΔTm–5°C),to a similar extent as heparin,suggesting that BACE1 inhibition by glycosaminoglycans may occur through a common mode of action,which may assist in the screening of glycan-based BACE1 inhibitors for Alzheimer’s disease.

Applying Both Chemical Liquefaction and Enzymatic Catalysis Can Increase Production of Agaro-Oligosaccharides from Agarose

Red algae represents an important marine bioresource.One high-value utilization of red algae is the production of agarooligosaccharides which have many positive biological effects.However,the lack of an efficient production route seriously limits the application of agaro-oligosaccharides.In this study,we established a green route that combines chemical liquefaction and enzymatic catalysis for the efficient production of agaro-oligosaccharides,and we used the production of neoagarotetraose(NA4)as an example.Agarose(150 g L^−1)liquefaction by citric acid was controlled with respect to two targets:a 100%liquefaction rate and a high average degree of polymerization(>4)of the liquesced agaro-oligosaccharides,which were then catalyzed byβ-agarase into an oligosaccharides mixture with a high concentration of NA4(30.8 g L^−1)in a 1-L reaction volume.After purification,we obtained 25.5 g of NA4 with a purity of 92%.This work establishes an easy route for the efficient production of pure agaro-oligosaccharides from agarose.