Effect of antioxidant compounds from seaweeds on storage stability of C20-22 polyunsaturated fatty acid concentrate prepared from dogfish liver oil.

Ethyl acetate extracts of seaweeds were chromatographically fractionated to yield 14-methyl pentyl tetrahydro-8-hydroxy-10-methylnaphthalene-8-carboxylate (1) and tetrahydro-4-isopropyl-9-(9, 14-dimethyldec-9-enyl)-pyran-1-one (2) from Sargassum ilicifolium, whereas Padina gymnospora afforded dihydro-2-(10-(hydroxymethyl)-7,15-dimethyl-9-oxoundec-11-enyl)-2-methyl-2H-pyran-1(4H)-one (3) and 1-(decahydro-1-hydroxy-7-methyl-8-vinylnaphthalen-2-yl)ethanone (4) as major constituents. Compound 1 displayed significantly higher antioxidant activity (IC50 < 1 mg/mL, p < 0.05) comparable to other analogues (IC50 > 1 mg/mL). The C20-22 polyunsaturated fatty acid (C20-22 PUFA) concentrate (CFA) prepared from the deep-sea dogfish liver oil was added with the studied compounds and physiochemical properties and fatty acid composition during an accelerated storage were evaluated. No significant reduction in C20-22 PUFAs (∼6%) in the CFA treated with 1 as compared to that with the control (∼35%) was recorded. A greater induction time was observed for the CFA supplemented with 1 (6.8 h) than other compounds (≤6 h) and control (∼1.6 h), maintaining the oxidation indices of the CFA within desirable limits.

Effects of antioxidative substances from seaweed on quality of refined liver oil of leafscale gulper shark, Centrophorus squamosus during an accelerated stability study.

Crude liver oil of leafscale gulper shark, Centrophorus squamosus was clarified by sequential degumming, decolorization and vacuum deodorization. The refined oil was added with ethyl acetate extract of seaweeds and various physiochemical parameters were evaluated in a time-reliant accelerated storage study. Significantly greater induction time was observed for the oil supplemented with Sargassum wightii and Sargassum ilicifolium (>4.5h) than other seaweed extracts and control oil (~1h). Among different seaweeds, the ethylacetate extracts of S. wightii maintained the oxidation indices of the refined oil below the marginal limits after the study period. No significant reduction in C20-22 long chain fatty acids (1.19%) in the refined oil added with S. wightii was apparent, and was comparable with the synthetic antioxidants (1.07-1.08%). Spectroscopic fingerprint analysis of marker compounds responsible to cause rancidity signified the efficacy of S. wightii to arrest the development of undesirable oxidation products in the refined oil during storage. The antioxidant compounds, 15-(but-19-enyl)-hexahydro-13,16-dimethyl-11-oxo-1H-isochromen-8-yl benzoate (1) and 10-(but-13-en-12-yl)-5-((furan-3-yl)propyl)-dihydrofuran-9(3H)-one (2) isolated from S. wightii appeared to play a major role to deter the oxidative degradation of refined oil thereby enhancing the storage stability.

Production and Biotechnological Application of Extracellular Alkalophilic Lipase from Marine Macroalga-Associated Shewanella algae to Produce Enriched C20-22 n-3 Polyunsaturated Fatty Acid Concentrate.

An extracellular alkalophilic lipase was partially purified from heterotrophic Shewanella algae (KX 272637) associated with marine macroalgae Padina gymnospora. The enzyme possessed a molecular mass of 20 kD, and was purified 60-fold with a specific activity of 36.33 U/mg. The enzyme exhibited Vmax and Km of 1000 mM/mg/min and 157 mM, respectively, with an optimum activity at 55 °C and pH 10.0. The catalytic activity of the enzyme was improved by Ca2+ and Mg2+ ions, and the enzyme showed a good tolerance towards organic solvents, such as methanol, isopropanol, and ethanol. The purified lipase hydrolyzed the refined liver oil from leafscale gulper shark Centrophorus squamosus, yielding a total C20-22 n-3 PUFA concentration of 34.99% with EPA + DHA accounting the major share (34% TFA), after 3 h of hydrolysis. This study recognized the industrial applicability of the thermostable and alkalophilic lipase from marine macroalga-associated bacterium Shewanella algae to produce enriched C20-22 n-3 polyunsaturated fatty acid concentrate.

Concentration and stabilization of C20-22 n-3 polyunsaturated fatty acid esters from the oil of Sardinella longiceps.

Methyl esters of C20-22n-3 polyunsaturated fatty acids derived from sardine oil triglycerides were concentrated to 86% purity with greater than 30% recovery by argentated chromatography. The synergistic effect of ethyl acetate fractions of seaweeds Kappaphycus alvarezii, Hypnea musciformis and Jania rubens used in 0.1:0.2:0.2 (%, w/w) ratio in arresting oxidative degradation of the n-3 PUFA methyl ester concentrate was demonstrated during accelerated storage. The induction time (6.8h) and antioxidant activity indices (>24) were greater for n-3 PUFA concentrates supplemented with seaweed extracts than antioxidants BHT and α-tocopherol (<5h and <17, respectively). Nuclear Magnetic Resonance spectroscopy was employed to study the oxidative changes of fatty acid signals of PUFA concentrate during accelerated storage. Potential of seaweeds to improve the storage stability of C20-22n-3 fatty acid methyl esters was studied. This study has applications in development of food and pharmaceutical products.

Biomimetic fiber assembled gradient hydrogel to engineer glycosaminoglycan enriched and mineralized cartilage: An in vitro study.

The study investigated the potential of electrospun fiber assembled hydrogel, with physical gradients of chondroitin sulfate (CS) and sol-gel-derived bioactive glass (BG), to engineer hyaline and mineralized cartilage in a single 3D system. Electrospun poly(caprolactone) (PCL) fibers incorporated with 0.1% w/w of CS (CSL) and 0.5% w/w of CS (CSH), 2.4% w/w of BG (BGL) and 12.5% w/w of BG (BGH) were fabricated. The CS showed a sustained release up to 3 days from CSL and 14 days from CSH fibers. Chondrocytes secreted hyaline like matrix with higher sulfated glycosaminoglycans (sGAG), collagen type II and aggrecan on CSL and CSH fibers. Mineralization was observed on BGL and BGH fibers when incubated in simulated body fluid for 14 days. Chondrocytes cultured on these fibers secreted a mineralized matrix that consisted of sGAG, hypertrophic proteins, collagen type X, and osteocalcin. The CS and BG incorporated PCL fiber mats were assembled in an agarose-gelatin hydrogel to generate a 3D hybrid scaffold. The signals in the fibers diffused and generated continuous opposing gradients of CS (chondrogenic signal) and BG (mineralization) in the hydrogel. The chondrocytes were encapsulated in hybrid scaffolds; live dead assay at 48 h showed viable cells. Cells maintained their phenotype and secreted specific extracellular matrix (ECM) in response to signals within the hydrogel. Continuous opposing gradients of sGAG enriched and mineralized ECM were observed surrounding each cell clusters on gradient hydrogel after 14 days of culture in response to the physical gradients of raw materials CS and BG. A construct with gradient mineralization might accelerate integration to subchondral bone during in vivo regeneration.