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Peptides found in marine life have various specific activities due to their special growth environment, and there is increasing interest in the isolation and concentration of these biofunctional compounds. In this study, the protein hydrolysate of the marine worm Urechis unicinctus was prepared by enzymolysis and enriched by using mesoporous materials of silica MCM-41 and SBA-15 and carbon CMK-3. The differences in pore structures and elemental composition of these materials lead to differences in surface area and hydrophobicity. The adsorption capacities of peptides were 459.5 mg g-1, 431.3 mg g-1, and 626.3 mg g-1 for MCM-41, SBA-15 and CMK-3, respectively. Adsorption kinetics studies showed that the pseudo-second-order model fit the adsorption process better, where both external mass transfer and intraparticle diffusion affected the adsorption, while the Langmuir model better fit the adsorption of peptides on MCM-41 and SBA-15 and the Freundlich model was more suitable for CMK-3. Aqueous acetonitrile (ACN, 50/50, v/v) yielded the most extracted peptides. MALDI-TOF mass spectrometry of the extracted peptides showed that the three mesoporous materials, especially the CMK-3, gave good enrichment results. This study demonstrates the great potential of mesoporous materials in the enrichment of marine biofunctional peptides.

In this study, we innovatively propose a fucoidan mixed with traditional Chinese medicine formula (FCM) and evaluate its effects on hyperglycaemia and diabetic nephropathy in a type II diabetes mellitus Wistar rat model. After treatment with FCM for 8 weeks, the blood glucose, insulin resistance, serum lipid and antioxidant stress levels were significantly decreased (P

Highly crystalline cellulose was isolated from kelp (Saccharina japonica) and used to prepare microcrystalline cellulose (MCC) via an optimized chemical–mechanical approach. The purity of the cellulose reached 99.9% (dry basis) according to HPLC and FT-IR analysis, with extraction yield reaching 9.9% on a dry kelp basis. The kelp cellulose (KC) had a degree of polymerization (DP) of 695, and featured natively highly crystalline structure with a crystallinity index (CrI) as high as 90.9% according to X-ray powder diffraction analysis. The KC was subjected to successive hydrochloric acid treatment and ball-milling to obtain MCC having a DP of 235 and a CrI of 88.6%. The kelp MCC exhibited comparable quality attributes to commercially available MCC. Polymorphic analysis based on peak deconvolution of the diffractograms revealed that the crystalline region of the kelp cellulose featured one-chain triclinic (Iα) rich polymorph, in contrast to two-chain monoclinic (Iβ) dominant structure found in higher-plant cellulose.

Fucoidan has been reported to have abundant biological activities. The objective of the present study was to detect the protective effects of fucoidan from Kjellmaniella crassifolia (KF) newly cultured in Dalian, North of China on aspirin-induced gastric ulcers of the Wistar rat model. The present study showed that inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and IL-10 were effectively regulated in rats pretreated with KF. Superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities increased significantly in the KF pretreated groups, while the levels of maleic dialdehyde (MDA) decreased. The findings obtained by RT-PCR and western blotting indicated that KF could suppress aspirin-induced NF-κB activation via stabilization of IκB-α and thereby induced the downregulation of COX-2 and iNOS. It was demonstrated that KF exerted positive gastric protective effects via suppression of the inflammatory response and oxidative stress, and the mechanism of KF appeared to mediate the NF-κB signaling pathway.

Fucoidan is a kind of brown algae-derived macromolecule suggested to have hypolipidemic activity. Saccharina sculpera has attracted interest because it is rich in fucoidan. The monosaccharide composition and structural characteristics of isolated fractions (F1, F2 and F3) were determined using high-performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). The hypolipidemic effects of fucoidan fractions from Saccharina sculpera cultured in northern China were clarified by measuring cholesterol levels, antioxidative indicators and hepatic gene mRNA expression using an established hyperlipidemic Wistar rat model. The results showed that F1 is an acetylated galactofucan and that F2 consists of fucose, galactose, mannose and glucuronic acid. F3 is an acetylated galactofucan with high fucose. Fucoidan fractions from Saccharina sculpera could effectively reduce the level of lipids in serum by reducing the TG, TC, and LDL-C levels and increasing HDL-C levels and could effectively prevent lipid accumulation in the liver. The findings obtained from hepatic gene expression showed that fucoidan could inhibit cholesterol synthesis via downregulation of HMG-CoA-R and upregulation of LCAT, slow the synthesis of fatty acids via downregulation of SREBP-1c, and promote β-oxidation of fatty acids via upregulation of PPARα, PPARγ and LPL. These results demonstrated that the hypolipidemic activity of fucoidan was related to the inhibition of cholesterol synthesis and reverse transport, the regulation of fatty acid synthesis, and acceleration of mitochondrial β-oxidation.

Endo-fucoidanases are important in structural analysis of fucoidans and preparation of fuco-oligosaccharides. However their enzymological properties and analysis of degradation products are scarcely investigated. Truncated endo-α (1 → 3)-fucoidanase Fda1 (tFda1B from Alteromonas sp. was overexpressed and characterized, showing highest activity at pH 7.0, 35 °C, and 1.0 M NaCl. Its Km and kcat were 3.88 ± 0.81 mg/mL and 0.82 ± 0.17 min−1. Fe3+ and Mn2+ enhanced activity by 100% and 19.5% respectively. Co2+ and Cu2+ completely inactivated tFda1B, whereas Ni2+, Mg2+, Zn2+, Pb2+, Ca2+, Ba2+ and Li+ decreased activity by 58.8%, 56.0%, 50.6%, 47.7%, 28.9%, 15.6% and 37.5%, respectively. Catalytic residues were identified through structure and sequence alignment, and confirmed by mutagenesis. Degradation products of Kjellmaniella crassifolia fucoidan by tFda1B were characterized by LC-ESI-MS/MS, confirming tFda1B belongs to endo-(1 → 3)-fucoidanases, and backbone of K. crassifolia fucoidan is 1 → 3 fucoside linkage. This endo-α (1 → 3)-fucoidanase would be useful for elucidating fucoidan structures, and be used as a food enzyme.

Fucoidan extracted from brown algae displays diverse biological activities. In the present study, fucoidan was mixed with Chinese herb extracts, and the in vitro and in vivo immunomodulatory effects of two fucoidan compound agents were evaluated. The results showed that fucoidan from Kjellmaniella crassifolia (KF) and Undaria pinnatifida (UF) were sulfated polysaccharides, Astragalus polysaccharide (AP) was composed of α-d-glucose, and Codonopsis pilosula polysaccharide (CPP) was a furanose. Furthermore, fucoidan compound agents stimulated mouse macrophage RAW264.7 cell proliferation and enhanced the secretion of granulocyte-macrophage colony stimulating factor (GM-CSF) and tumour necrosis factor-α (TNF-α) in vitro. In addition, KCA (KF + AP + CPP) and UCA (UF + AP + CPP) could improve the nonspecific immunity and the specific immunity of BALB/c mice. Fucoidan compound agents also increased the secretion of GM-CSF, TNF-α, interleukin (IL)-4 and IL-10 in vivo. Therefore, we confirmed that fucoidan compound agents have promise for development as supplementary immunopotentiators.

For illustrating the relation of different structural characteristics correlated with the hepatoprotective effect, studies of fucoidan from algae Kjellmaniella crassifolia, a brown alga distributed in north Japan, were carried out. The fucoidan fractions of K. crassifolia were extracted, separated, and purified using a combinatorial procedure consisting of enzymolysis, ethanol precipitation, DEAE and size-exclusion chromatographies. The fundamental characteristics of the four enriched fucoidan fractions (KF1-KF4), including their sulphate content and monosaccharide composition, were investigated. The fucose was the main composition of monosaccharide for KF1-KF4, that of KF4 was up to 91.4%. The Glu-UA was the special composition of monosaccharide. FTIR and NMR spectroscopy were employed to elucidate the structural features of all fractions which further illustrated that fucose was the main monosaccharide. It was found all the four fractions showed antioxidative activity against hydroxyl radical and had the bioactive effects on CCl4-induced liver injury.

Brown alga-derived fucoidan has been proven to have a variety of bioactivities. To explore the antitumor effect of fucoidan, Kjellmaniella crassifolia (farmed in Dalian, China)was enzymatically digested to obtain the crude extract (F), which was further separated into three fractions (F1, F2 and F3). The monosaccharide composition and structural characteristics of the isolated fractions were determined using high-performance liquid chromatography (HPLC), Fourier-transform infrared spectroscopy (FTIR) and 1D and 2D nuclear magnetic resonance (NMR) spectroscopy. F1 is an acetylated galactofucan, and F2 consists of fucose, galactose, mannose and glucuronic acid. F3 has two components, an acetylated galactofucan and a pure sulfated fucan. F, F1 and F2 showed limited cytotoxicity against murine hepatocarcinoma Hca-F cells in vitro. Oral administration of F at a dose of 450 mg/kg d significantly inhibited lump growth in Hca-F-inoculated mice and led to upregulated FAS expression in tumor tissues compared to that of the control. F1 and F2 did not show competitive antineoplastic efficacy, as did the crude extract. Crude fucoidan could be a promising antitumor adjuvant. The origin of its efficacy may be the small molecules, such as phenols that attached to native fucoidan. This theory needs to be further confirmed.

The antioxidative activity of hydrolysate peptides from oysters (Crassostrea talienwhanensis) was investigated. After hydrolysis with subtilisin, the yields of the peptides that were soluble in trichloroacetic acid (TCA-soluble) and the antioxidant activities of the resulting hydrolysate were determined using an orthogonal design and a hydroxyl radical scavenging reaction. The hydrolysate was fractionated using Sephadex G-15 gel filtration chromatography, and the two resulting bioactive peptides were subsequently purified by RP-HPLC with a Kromasil C18 (ODS) column. The amino acid sequences were analyzed by nano-ESI-MS/MS. The critical reaction temperature, pH, hydrolysis time and enzyme-to-substrate (E/S) ratio were determined for the optimum hydrolysis with subtilisin, and the E/S ratio was found to be the most critical reaction condition. The amino acid sequences of the peptides (518 and 440 Da) were proline-valine-methionine-glycine-aspartic acid (PVMGA) and glutamine-histidine-glycine-valine (QHGV), respectively. These two novel peptides exhibited high antioxidative actions based on their hydroxyl and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities.

Fucoidan is a well-known natural product that is commonly found in brown algae and shows a variety of activities, including immunomodulation, antioxidation, and the combat of carcinogens. The fucoidan fractions of Costaria costata, a brown algae introduced from Japan and cultured in northern China, were studied. The fucoidan fractions were extracted, separated, and purified using a combinatorial procedure consisting of enzymolysis, ethanol precipitation, and DEAE and size-exclusion chromatographies. The fundamental characteristics of the four enriched fucoidan fractions (F1-F4), such as their sulphate content and monosaccharide composition, were investigated. FTIR and NMR spectroscopy were employed to further elucidate the structural features of the four fractions. It was found that the F1-F4 fractions all showed oxidative activity against hydroxyl radicals. The bioactive effects of the fucoidan fractions on CCl4-induced liver injury suggest their potential use as ingredients for functional foods or pharmaceuticals.