Sequence determination of a non-sulfated glycosaminoglycan-like polysaccharide from melanin-free ink of the squid Ommastrephes bartrami by negative-ion electrospray tandem mass spectrometry and NMR spectroscopy

Insights into Common Octopus (Octopus vulgaris) Ink Proteome and Bioactive Peptides Using Proteomic Approaches

The common octopus (Octopus vulgaris) is nowadays the most demanded cephalopod species for human consumption. This species was also postulated for aquaculture diversification to supply its increasing demand in the market worldwide, which only relies on continuously declining field captures. In addition, they serve as model species for biomedical and behavioral studies. Body parts of marine species are usually removed before reaching the final consumer as by-products in order to improve preservation, reduce shipping weight, and increase product quality. These by-products have recently attracted increasing attention due to the discovery of several relevant bioactive compounds. Particularly, the common octopus ink has been described as having antimicrobial and antioxidant properties, among others. In this study, the advanced proteomics discipline was applied to generate a common octopus reference proteome to screen potential bioactive peptides from fishing discards and by-products such as ink. A shotgun proteomics approach by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) using an Orbitrap Elite instrument was used to create a reference dataset from octopus ink. A total of 1432 different peptides belonging to 361 non-redundant annotated proteins were identified. The final proteome compilation was investigated by integrated in silico studies, including gene ontology (GO) term enrichment, pathways, and network studies. Different immune functioning proteins involved in the innate immune system, such as ferritin, catalase, proteasome, Cu/Zn superoxide dismutase, calreticulin, disulfide isomerase, heat shock protein, etc., were found in ink protein networks. Additionally, the potential of bioactive peptides from octopus ink was addressed. These bioactive peptides can exert beneficial health properties such as antimicrobial, antioxidant, antihypertensive, and antitumoral properties and are therefore considered lead compounds for developing pharmacological, functional foods or nutraceuticals.

Structural and functional analysis of a tandem repeat galacturonic acid-binding lectin from the sea hare Aplysia californica

A d-galacturonic acid-specific lectin, named AcL, was purified from the sea hare Aplysia californica by galactose-agarose affinity chromatography. AcL has a molecular mass of 27.5 kDa determined by MALDI-TOF mass spectrometry. This lectin shows a good affinity for d-galacturonic acid and a lower affinity for galactosides: raffinose, melibiose, α and β-lactose, and d-galactose. We determined the amino acid sequence of AcL by trypsin digestion and subsequent peptide analysis by mass spectrometry, resulting in a 238 amino acid protein with a theoretical molecular mass of 26.4 kDa. The difference between the theoretical and experimental values can be attributed to post-translational modifications. Thiol-disulfide quantification discerned five disulfide bonds and three free cysteines. The structure of Acl is mainly comprised of beta sheets, determined by circular dichroism, and predicted with AlphaFold. Theoretical models depict three nearly identical tandem domains consisting of two beta sheets each. From docking analysis, we identified AcL glycan-binding sites as multiple conserved motifs in each domain. Furthermore, phylogenetic analysis based on its structure and sequence showed that AcL and its closest homologues (GalULs) form a clear monophyletic group, distinct from other glycan-binding proteins with a jelly-roll fold: lectins of types F and H. GalULs possess four conserved sequence regions that distinguish them and are either ligand-binding motifs or stabilizing network hubs. We suggest that this new family should be referred to as GalUL or D-type, following the traditional naming of lectins; D standing for depilans, the epithet for the species (Aplysia depilans) from which a lectin of this family was first isolated and described.

Effects of a sulfated glycosaminoglycan from Sepia esculenta ink on transcriptional and metabolic profiles of Saccharomyces cerevisiae

Four fractions of water-extracted Sepia esculenta ink polysaccharides (SIP) were separated by dicthylaminoethy (DEAE) cellulose chromatography. The eluted fraction with the highest yield was characterized as a sulfate-rich glycosaminoglycan named SIP-IV. According to the analysis of laser scattering and refractive index signals, SIP-IV was determined to be 14.4 kDa and spherical molecular conformation in salt solution. SIP-IV is composed of fucose, galactosamine, glucosamine, mannose and glucuronic acid with a molar ratio of 5.1:7.3:3.8:1:4.4, which is obviously different from reported SIPs. SIP-IV promoted yeast proliferation and intercellular antioxidant level. Based on multi-omics strategy, data of transcriptome analysis suggested that growth promotion of SIP-IV on Saccharomyces cerevisiae might be attributed to regulation of Rho protein signal transduction, nuclear autophagy and nitrogen utilization. Combined with the metabolome results, SIP-IV also re-profiled metabolism of amino acids and phospholipids in yeast cells.

Effect of steaming process on the structural characteristics and antioxidant activities of polysaccharides from Polygonatum sibiricum rhizomes

Polygonatum sibiricum (P. sibiricum) rhizomes are widely used as a tonic and functional food, and are often processed to enhance their tonic function by repeated steaming and drying. As the most important constituent, the polysaccharide from P. sibiricum rhizomes (PSP) has demonstrated various activities, but the alteration of structural characteristics and activities of the purified PSPs during steaming process was rarely investigated. To well understand the effect of steaming process on the polysaccharides of P. sibiricum, neutral polysaccharides from P. sibiricum rhizomes (PSP0 ~ PSP9) after steaming were first isolated and purified, and then the chemical properties and antioxidant activities were determined. The results showed that the molar ratios of monosaccharides in PSPs were different. The molecular weights of PSPs were increased significantly after the fourth steaming. Morphological studies showed that the surface of PSPs became much tighter during the steaming process. Fourier transform infrared spectroscopy spectra displayed the polysaccharides had similar backbones and chemical groups. Furthermore, the antioxidant activity of PSPs was measured through radical scavenging tests. It was found that the radical scavenging activity of PSPs was elevated strikingly after steaming, and increased gradually with numbers of steaming process. The biological and chemical variance of PSPs revealed considerable segregation of PSP0, PSP1 ~ PSP4 and PSP5 ~ PSP9. In conclusion, our results proposed the fourth time as the optimal number of steaming to extract functional polysaccharide from P. sibiricum rhizomes.

Highly sialylated mucin-type glycopeptide from porcine intestinal mucosa after heparin extraction: O-glycan profiling and immunological activity evaluation

Mucins are the major proteins that distributed on the intestinal mucosa layer and protect the intestine from pathogens infection. The composition of intestinal mucin O-glycans can affect the health of the gastrointestinal tract in pigs. Porcine intestinal mucosa is widely used as the main raw material of heparin extraction. The heparin extraction residues rich in mucins were usually wasted. The structure of mucin derived O-glycans in porcine intestinal mucosa are currently unknown. In this study, we isolated the mucins from the heparin extraction residues and profiled the O-glycans. After heparin extraction, mucin was digested with trypsin, and separated by strong anion exchange chromatography. The mucin derived O-glycans were release by alkaline β elimination, and analyzed by ultra high performance liquid chromatography-porous graphitized carbon-Fourier transform mass spectrometry (UPLC-PGC-FTMS/MS). Thirty five kinds of O-glycans were identified, most of which were Core 3-derived glycans. In particular, the O-glycans containing sialic acid Neu5Ac accounted for 71.93% of the total O-glycans, which were different from that of other species, including mouse intestine, fish intestine, and porcine colon. The high content sialylated mucin may explain its effect in biological processes. Furthermore, the immunological activity results indicated that the porcine intestinal mucin could promote phagocytosis and proliferation without any cytotoxic effects, which may aid in the development of immunomodulators.

Fucoidan from sea cucumber Holothuria polii: Structural elucidation and stimulation of hematopoietic activity

The structural elucidation of polysaccharides is essential for understanding their structure-bioactivity relationship and related drug development. In this study, fucoidan (Fuc_hp) was extracted and purified from sea cucumber Holothuria polii. Its sulfate content was 39.5 ± 1.4%, and the "weight-average" molecular mass was 103.1 ± 2.8 kDa. The primary structure of Fuc_hp was clarified using a combination of acid degradation, tandem mass spectrometry, and nuclear magnetic resonance spectroscopy analysis. As a result, Fuc_hp was found to be composed of a tetrafucose repeating unit [→3-α-l-Fucp-1 → 3-α-l-Fucp2(OSO₃^-)-1 → 3-α-l-Fucp2(OSO₃^-)-1 → 3-α-l-Fucp2,4(OSO₃^-)-1→]. The stimulating hematopoiesis was further evaluated in a mouse model induced by cyclophosphamide. Based on these findings, intraperitoneally administered Fuc_hp may accelerate the recovery of white blood cells and neutrophils, in which its activity exceeded that of recombinant human granulocyte colony-stimulating factor (rhG-CSF). Meanwhile, in the background of cyclophosphamide-induced immunosuppression, treatment with Fuc_hp reduces platelet aggregation caused by CTX, so it might have the effect of reducing the risk of thrombosis. Therefore, Fuc_hp can be exploited as potentially promising stimulator of hematopoiesis in the future.

Alkaline Extraction, Structural Characterization, and Bioactivities of (1→6)-β-d-Glucan from Lentinus edodes

The purpose of this study is to develop a robust approach to obtain β glucans from Lentinus edodes and to characterize their structural and biological properties for sustainable utilization. The alkali extraction was optimized with an orthogonal experimental design, and a concise process for obtaining specific targeting polysaccharides from Lentinus edodes was developed in this study. After purification with a Q-Sepharose Fast Flow strong anion-exchange column, the monosaccharide composition, a methylation analysis, and NMR spectroscopy were employed for their structural characterizations. LeP-N2 was found to be composed of (1→6)-β-d-glucans with minor β-(1→3) glucosidic side chains. Atomic force microscopy (AFM) and high-performance gel permeation chromatography–refractive index–multi-angle laser light scattering (HPGPC-RI-MALLS) also revealed LeP-N2 exhibiting a compact unit in aqueous solution. This (1→6)-β-d-glucan was tested for antioxidant activities with IC₅₀ at 157 μg/mL. Moreover, RAW 264.7 macrophage activation indicated that the release of nitric oxide (NO) and reactive oxygen species (ROS) were markedly increased with no cytotoxicity at a dose of 100 μg/mL. These findings suggest that the (1→6)-β-d-glucans obtained from Lentinus edodes could serve as potential agents in the fields of functional foods or medicine.

Profiling and Structural Characterization of High Neu5Gc or Sulfate-containing O-glycans from Hyla Rabbit Intestinal Mucin

Intestinal mucins constitute the major component of the mucus covering the epithelium of the gastrointestinal tract, thereby forming a barrier against microbial colonization. Rabbits are bred in large numbers worldwide, with little known about intestinal O-glycosylation despite this insight being crucial to the understanding of host-pathogen interactions. In the present study, a major mucin-type glycopeptide (RIF6) of hyla rabbit intestine was isolated and the O-glycans were extensively characterized based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) combined with bioinformatics approaches. Thirty-three O-glycans were identified, and most of them were sulfated or sialylated glycans. It was worth noting that Neu5Gc-containing structures within sialylated O-glycans accounted for 91%, which were extremely different from that of other species including humans, mice, chickens, etc. Sulfated glycans accounted for 58%, unique disufated and sulfated-sialylated glycans were also detected in rabbit intestinal mucin. These structural characterization reflected species diversity and may provide deeper insights into explaining the adaptability of hyla rabbit to the environment.

Structure and Neuroprotective Effect of Polysaccharide from Viscera Autolysates of Squid Ommastrephes bartrami

To explore bioactive polysaccharides from the byproducts of squid processing, a heteropolysaccharide, named SV2-1, was isolated from the viscera of squid Ommastrephes bartrami by autolysis, anion-exchange and gel-permeation chromatography and measured for its neuroprotective activity. It was a homogeneous polysaccharide with a molecular weight of 2.3 kDa by HPSEC analysis. SV2-1 contained glucuronic acid, galactosamine and fucose in the ratio of 1.0:1.1:1.2. Its structural characteristics were elucidated by methylation analysis, gas chromatography-mass spectrometry (GC-MS), and nuclear magnetic resonance (NMR). The backbone of SV2-1 was composed of alternant →4)-α-l-Fucp-(1→ and →3)-β-d-GlcUA-(1→ Most of →4)-α-l-Fucp-(1→ (90%) was substituted by single α-d-GlcNAc as the branches. SV2-1 can protect against the death of PC12 induced by 6-OHDA, and effectively improves cell viability and reduces extracellular LDH release in PC12 cells after injury. Moreover, SV2-1 significantly increases SOD activity but decreases MDA levels.

Structural characterization and anti-thrombotic properties of fucoidan from Nemacystus decipiens

The sulfated polysaccharide NP2 was isolated and purified from Nemacystus decipiens, the structure and antithrombotic activity of NP2 was further studied. NP2 was composed of fucose, glucuronic acid, galactose and xylose at molar ratios of 76.3:20.5:1.5:1.7. ES-CID-MS/MS results showed that NP2 had a backbone of α (1 → 3)-linked fucose and a branch was composed of Fuc-(2 → 1)-GlcA, which was agree with the results of NMR and methylation analysis. The results also show that the sulfate groups were substituted at the C2 or C4 positions of the fucose residues. In addition, analysis of the antithrombotic activity results indicated that NP2 can increase the percentage of t-PA/PAI-1, thereby suggesting that NP2 has high fibrinolytic activity and should be explored as a novel antithrombotic agent.

A β-glucan from Durvillaea Antarctica has immunomodulatory effects on RAW264.7 macrophages via toll-like receptor 4

We studied the mechanisms underlying the immunostimulatory effects of aβ-1,3/1,6-glucan (BG136) from Durvillaea Antarctica. Our data showed that BG136 promoted the activation of MAPKs and NF-κB signaling pathways and cytokines production. BG136 did not increase MCP-1 or NO production or phosphorylation of NF-κB and MAPK in TLR4 siRNA knockdown cells, indicating that BG136 activates macrophages through TLR4. Flow cytometry analysis and confocal experiment showed that BG136 bound to TLR4 expressed on RAW264.7 macrophage cells surface. The affinity of BG136 for TLR4 was determined using Surface Plasmon Resonance (SPR) (KD: 4.51 × 10-6M). Altogether, our results showed that BG136 activates RAW264.7 cells by binding to TLR4 and then triggering TLR4-mediated signaling pathways to promote cytokines secretion.

Structural Characterization and Interaction with RCA120 of a Highly Sulfated Keratan Sulfate from Blue Shark (Prionace glauca) Cartilage

As an important glycosaminoglycan, keratan sulfate (KS) mainly exists in corneal and cartilage, possessing various biological activities. In this study, we purified KS from blue shark (Prionace glauca) cartilage and prepared KS oligosaccharides (KSO) through keratanase II-catalyzed hydrolysis. The structures of KS and KSO were characterized using multi-dimensional nuclear magnetic resonance (NMR) spectra and liquid chromatography-mass spectrometry (LC-MS). Shark cartilage KS was highly sulfated and modified with ~2.69% N-acetylneuraminic acid (NeuAc) through α(2,3)-linked to galactose. Additionally, KS exhibited binding affinity to Ricinus communis agglutinin I (RCA₁₂₀) in a concentration-dependent manner, a highly toxic lectin from beans of the castor plant. Furthermore, KSO from dp2 to dp8 bound to RCA₁₂₀ in the increasing trend while the binding affinity of dp8 was superior to polysaccharide. These results define novel structural features for KS from Prionace glauca cartilage and demonstrate the potential application on ricin-antidote exploitation.

A Potential Adjuvant Agent of Chemotherapy: Sepia Ink Polysaccharides

Sepia ink polysaccharide (SIP) isolated from squid and cuttlefish ink is a kind of acid mucopolysaccharide that has been identified in three types of primary structures from squid (Illex argentinus and Ommastrephes bartrami), cuttlefish Sepiella maindroni, and cuttlefish Sepia esculenta ink. Although SIP has been proved to be multifaceted, most of the reported evidence has illuminated its chemopreventive and antineoplastic activities. As a natural product playing a role in cancer treatment, SIP may be used as chemotherapeutic ancillary agent or functional food. Based on the current findings on SIP, we have summarized four topics in this review, including: chemopreventive, antineoplastic, chemosensitive, and procoagulant and anticoagulant activities, which are correlative closely with the actions of anticancer agents on cancer patients, such as anticancer, toxicity and thrombogenesis, with the latter two actions being common causes of death in cancer cases exposed to chemotherapeutic agents.

A novel structural fucosylated chondroitin sulfate from Holothuria Mexicana and its effects on growth factors binding and anticoagulation

Fucosylated chondroitin sulfate (FCS), a structurally distinct glycosaminoglycan from the body wall of sea cucumber, possesses many biological properties and pharmacology functions. The refined structure of FCS isolated from sea cucumber Holothuria Mexicana (FCS_hm) was characterized by NMR spectra and HILIC-FTMS, which demonstrated four types of branches in FCS_hm. Among these, two branches were α-L-Fuc-2S4S (where Fuc is fucose and S is sulfo) and α-L-Fuc-4S linked to O-3 of glucuronic acid residues, while others were identified as α-L-Fuc-4S and α-L-Fuc-3S4S attached to O-6 of N-acetylgalactosamine residue. Furthermore, the fucosyl branches were α-1,3-linked with different degree of polymerization from 1 to 5. FCS_hm exhibited high affinity to fibroblast growth factor 1 and 2, growth factors involved in neovascularization. Moreover, FCS_hm displayed intrinsic anticoagulant activity and inhibited thrombin and factor Xa activation by antithrombin III. Our results proposed a novel structural FCS and demonstrated its favorable application prospects in anti-angiogenesis and anticoagulation.

Inhibition of chemotherapy-induced apoptosis of testicular cells by squid ink polysaccharide

The aim of this study was to determine the mechanisms driving the protective effects of squid ink polysaccharide (SIP) against cyclophosphamide (CP)-induced testicular damage, focusing on germ cells. In the testes of mice exposed to CP and/or SIP, the present study examined the levels of reactive oxygen species (ROS) and malondialdehyde, activity of superoxide dismutase levels, protein expression levels of B-cell lymphoma 2 (Bcl2), Bcl2-associated X protein (Bax), and total Caspase 3, activation of p-p38 and p-Akt proteins, and tissue morphology. The findings indicated that CP induced ROS production and oxidative stress, resulting in testicular damage. However, under administration of SIP, oxidative stress was impaired and the testicular toxicity induced by CP was weakened, which implied that SIP may have an important role in preventing chemotherapeutic damage to the male reproductive system via promoting antioxidant ability. Furthermore, the altered expression levels, including the upregulation of Bax and Caspase 3, downregulation of Bcl-2 and the increased Bax/Bcl-2 ratio, indicated that apoptosis occurred in CP exposed testes of mice; however, the alterations were reversed in mice treated with SIP. Moreover, in CP-exposed testes, p38 and Akt proteins were significantly phosphorylated (P<0.05), whereas in the testes of mice co-treated with SIP and CP, phosphorylation of the two proteins was inhibited, demonstrating that the two signalling pathways participated in the regulative processes of the deleterious effects caused by CP, and the preventive effects SIP mediated.

Gut microbiota fermentation of marine polysaccharides and its effects on intestinal ecology: An overview

The gut microbiota that resides in the mammalian intestine plays a critical role in host health, nutrition, metabolic and immune homeostasis. As symbiotic bacteria, these microorganisms depend mostly on non-digestible fibers and polysaccharides as energy sources. Dietary polysaccharides that reach the distal gut are fermented by gut microbiota and thus exert a fundamental impact on intestinal ecology. Marine polysaccharides contain a class of dietary fibers that are widely used in food and pharmaceutical industries (e.g., agar and carrageenan). In this regard, insights into fermentation of marine polysaccharides and its effects on intestinal ecology are of vital importance for understanding the beneficial effects of these glycans. Here, in this review, to provide an overlook of current advances and facilitate future studies in this field, we describe and summarize up-to-date findings on how marine polysaccharides are metabolized by gut microbiota and what effects these polysaccharides have on intestinal ecology.

Fucosylated chondroitin sulfate oligosaccharides exert anticoagulant activity by targeting at intrinsic tenase complex with low FXII activation: Importance of sulfation pattern and molecular size

Fucosylated chondroitin sulfates (fCSs) are structurally unusual glycosaminoglycans isolated from sea cucumbers that exhibit potent anticoagulant activity. These fCSs were isolated from sea cucumber, Isostichopus badionotus and Pearsonothuria graeffei. Fenton reaction followed by gel filtration chromatography afforded fCS oligosaccharides, with different sulfation patterns identified by mass and NMR spectroscopy, and these were used to clarify the relationship between the structures and the anticoagulant activities of fCSs. In vitro activities were measured by activated partial thromboplastin time (APTT), thrombin time (TT), thrombin and factor Xa inhibition, and activation of FXII. The results showed that free radicals preferentially acted on GlcA residues affording oligosaccharides that were purified from both fCSs. The inhibition of thrombin and factor X activities, mediated through antithrombin III and heparin cofactor II of fCSs oligosaccharides were affected by their molecular weight and fucose branches. Oligosaccharides with different sulfation patterns of the fucose branching had a similar ability to inhibit the FXa by the intrinsic factor Xase (factor IXa-VIIIa complex). Oligosaccharides with 2,4-O-sulfo fucose branches from fCS-Ib showed higher activities than ones with 3,4-O-disulfo branches obtained from fCS-Pg. Furthermore, a heptasaccharide is the minimum size oligosaccharide required for anticoagulation and FXII activation. This activity was absent for fCS oligosaccharides smaller than nonasaccharides. Molecular size and fucose branch sulfation are important for anticoagulant activity and reduction of size can reverse the activation of FXII caused by native fCSs.

Preventive Effects of a Novel Polysaccharide from Sepia esculenta Ink on Ovarian Failure and Its Action Mechanisms in Cyclophosphamide-Treated Mice

On the basis of our findings about chemo-preventive roles of squid ink polysaccharide and the well-known toxicity of cyclophosphamide (CP) on female gonad, this research investigated the protective effects of a novel polysaccharide from Sepia esculenta ink (SEP) on the ovarian failure resulting from CP, as well as the action mechanisms underpinning this. The results indicated that CP destroyed the ovaries of mice which caused depletion of various follicles, and led to a reduction in estradiol content, increases in FSH and LH contents in sera, decreases in ovary and uterus masses and their relative mass ratios, disruption of the ultrastructure of granulosa cells, as well as induction of apoptosis and autophagy via p38 MAPK and PI3K/Akt signaling pathways. The phenomenon resulted in ovarian failure. However, SEP exposure altered the negative effects completely. The data indicated that SEP can effectively prevent ovarian failure CP caused in mice by inhibiting the p38 MAPK signaling pathway and activating the PI3K/Akt signaling pathway as regulated by CP. SEP was a novel polysaccharide from Sepia esculenta ink with a unique primary structure mainly composed of GalN and Ara that accounted for almost half of all monosaccharides: their ratio was nearly one-to-one. Besides, the polysaccharide contained a small number of Fuc and tiny amounts of Man, GlcN, GlcA, and GalA.

Dietary squid ink polysaccharide could enhance SIgA secretion in chemotherapeutic mice

Secretory immunoglobulin A (SIgA) is a non-inflammatory antibody that shields internal body surfaces, such as in the intestine to neutralize pathogens in the lumen of the intestine. As chemotherapy seriously damages the mucosal immune system, we herein demonstrated that polysaccharide from the squid ink of Ommastrephes bartrami (OBP) activated intestinal SIgA secretion to prevent chemotherapeutic injury. Using a mouse model of chemotherapy induced intestinal injury by intraperitoneal injection of 50 mg kg(-1) cyclophosphamide, our results showed an enhanced SIgA concentration in intestinal mucosa by OBP administration and the higher production of SIgA relied on the greater expression of IgA, J chain and pIgR. Furthermore, the higher expressions of IL-6, IL-10 and TNF-α increased by OBP treatment contributed to enhanced IgA and J chain synthesis in IgA(+) plasma cells, and pIgR expression in epithelial cells. It also triggered a prompt immunoglobulin secretory pathway confirmed by enhanced UPR (unfolded protein response) effectors XBP-1s and Bip expression. Our results have important implications for the mucosal immunity enhancement effects of OBP as a functional food component for chemotherapeutic patients.

Extraction, Isolation, Structural Characterization and Anti-Tumor Properties of an Apigalacturonan-Rich Polysaccharide from the Sea Grass Zostera caespitosa Miki

An apigalacturonan (AGA)-rich polysaccharide, ZCMP, was isolated from the sea grass Zostera caespitosa Miki. The depolymerized fragments derived from ZCMP were obtained by either acidic degradation or pectinase degradation, and their structures were characterized by electrospray ionization collision-induced-dissociation mass spectrometry (ESI-CID-MS2) and nuclear magnetic resonance (NMR) spectroscopy. The average molecular weight of ZCMP was 77.2 kD and it consisted of galacturonic acid (GalA), apiosefuranose (Api), galactose (Gal), rhamnose (Rha), arabinose (Ara), xylose (Xyl), and mannose (Man), at a molar ratio of 51.4꞉15.5꞉6.0꞉11.8꞉4.2꞉4.4꞉4.2. There were two regions of AGA (70%) and rhamnogalacturonan-I (RG-Ι, 30%) in ZCMP. AGA was composed of an α-1,4-D-galactopyranosyluronan backbone mainly substituted at the O-3 position by single Api residues. RG-Ι possessed a backbone of repeating disaccharide units of →4GalAα1,2Rhaα1→, with a few α-L-arabinose and β-D-galactose residues as side chains. The anti-angiogenesis assay showed that ZCMP inhibited the migratory activity of human umbilical vein endothelial cell (HUVECs), with no influence on endothelial cells growth. ZCMP also promoted macrophage phagocytosis. These findings of the present study demonstrated the potential anti-tumor activity of ZCMP through anti-angiogenic and immunoregulatory pathways.

The squid ink polysaccharides protect tight junctions and adherens junctions from chemotherapeutic injury in the small intestinal epithelium of mice

Gastrointestinal mucositis and infection by chemotherapy treatment are associated with alterations in the functioning of the intestinal barrier, due to the potential damage induced by anticancer drugs on the epithelial tight junctions and adheren junction. We aimed to study the protective effect of dietary polysaccharides on chemotherapy-induced injury in the epithelial cells. In the current study, using mice that were intraperitoneally injected with 50 mg/kg cyclophosphamide for 2 days, we reveal that polysaccharides from the ink of Ommastrephes bartrami (OBP) enhanced the mRNA and protein expression levels of Occludin, zonulae occluden (ZO)-1, and E-cadherin. Immunohistochemistry staining of ZO-1 and E-cadherin confirmed the increase in the mRNA and protein levels. OBP also remarkably enhanced the mRNA expression of other tight junction proteins, ZO-2, ZO-3, claudin-2, and cingulin. Our results may have important implications in host defense, especially the immunopotentiation function of OBP on the cyclophosphamide-induced epithelial cell injury, as well as intestinal disorders involving inflammation and infection.

Dietary squid ink polysaccharide induces goblet cells to protect small intestine from chemotherapy induced injury

Gastrointestinal mucositis induced by chemotherapy is associated with alterations of intestinal barrier function due to the potential damage induced by anti-cancer drugs on the epithelial cells.

Isolation and structure characterization of an antioxidative glycopeptide from mycelial culture broth of a medicinal fungus

A novel glycopeptide (Cs-GP1) with an average molecular weight (Mw) of 6.0 kDa was isolated and purified by column chromatography from the lower Mw fraction of exopolysaccharide (EPS) produced by a medicinal fungus Cordyceps sinensis Cs-HK1. Its carbohydrate moiety was mainly composed of glucose and mannose at 3.2:1.0 mole ratio, indicating an O-linked glycopeptide. The peptide chain contained relatively high mole ratios of aspartic acid, glutamic acid and glycine (3.3–3.5 relative to arginine) but relatively low ratios of tyrosine and histidine. The peptide chain sequence analyzed after trypsin digestion by LC-MS was KNGIFQFGEDCAAGSISHELGGFREFREFLKQAGLE. Cs-GP1 exhibited remarkable antioxidant capacity with a Trolox equivalent antioxidant capacity of 1183.8 μmol/g and a ferric reducing ability of 611.1 μmol Fe(II)/g, and significant protective effect against H₂O₂-induced PC12 cell injury at a minimum dose of 10 μg/mL. This is the first report on the structure and bioactivity of an extracellular glycopeptide from the Cordyceps species.

Effectiveness of treatment of iron deficiency anemia in rats with squid ink melanin-Fe

Iron deficiency anemia (IDA) is the one of the most common nutritional problems and is encountered all over the world. This study analysed the effects of squid ink melanin-Fe (SM-Fe) on IDA in rats. Forty weanling SD male rats were used and thirty-two rats were fed an iron-deficient diet for 4 weeks. Then SM-Fe (dosages of iron is 6 mg kg(-1) BW) was given to the IDA rats once a day for 3 weeks by intragastric administration, with FeCl3 and FeSO4 (dosages of iron is 6 mg kg(-1) BW) as positive controls. While the IDA model group and the control group were administrated distilled deionized water each day for 3 weeks. The content of haemoglobin (Hb), serum iron (SI), total iron binding capacity (TIBC), serum ferritin (SF), transferrin receptor (sTfR), erythropoietin (EPO), and iron content in the liver and spleen were measured. The results showed that the content of Hb, SI, SF, EPO, iron content in the liver and spleen were significantly increased in the iron supplement groups (SM-Fe, FeCl3 and FeSO4) compared with the model group (P < 0.05), while TIBC and sTfR were significantly decreased in the iron supplement groups compared with the model group (P < 0.05). In comparison with the FeCl3 and FeSO4 groups, a higher bioavailability of iron and fewer side effects were observed in the SM-Fe group. The present study indicated that SM-Fe is an effective source of iron supplement for IDA rats and might be exploited as a new iron fortifier.

Dietary squid ink polysaccharides ameliorated the intestinal microflora dysfunction in mice undergoing chemotherapy

Gastrointestinal mucositis and infection by chemotherapy treatment are associated with alteration of intestinal microflora and bacterial translocation due to the potential damage induced by anti-cancer drugs on the intestinal barrier and microbiota homeostasis. This study aimed to investigate the protective effect of dietary polysaccharides on chemotherapy induced intestinal microflora dysfunction. In the current contribution, with a mouse model intraperitoneally injected with 50 mg kg(-1) of cyclophosphamide (Cy) for 2 days, we revealed that polysaccharides from the ink of Ommastrephes bartrami (OBP) altered the intestinal microflora composition. OBP retarded the excessive growth of intestinal bacteria induced by cyclophosphamide, based on 16S rRNA gene (16S rDNA) quantification. The clone libraries of intestinal bacteria 16S rDNA were used to decipher the difference in bacterial community structures in different groups of mice. Followed by RFLP evaluation and OTU abundance analysis, they imply that OBP changed the intestinal microflora composition, in which the quantity of probiotic Bifidobacterium got up-regulated but Bacteroidetes decreased in mice undergoing chemotherapy. Our results may have important implications for OBP as a functional food component or nutrient against chemotherapy induced intestinal injury and potential pathogenic intestinal disorders involving inflammation and infection.

Applications of mass spectrometry to structural analysis of marine oligosaccharides

Marine oligosaccharides have attracted increasing attention recently in developing potential drugs and biomaterials for their particular physical and chemical properties. However, the composition and sequence analysis of marine oligosaccharides are very challenging for their structural complexity and heterogeneity. Mass spectrometry (MS) has become an important technique for carbohydrate analysis by providing more detailed structural information, including molecular mass, sugar constituent, sequence, inter-residue linkage position and substitution pattern. This paper provides an overview of the structural analysis based on MS approaches in marine oligosaccharides, which are derived from some biologically important marine polysaccharides, including agaran, carrageenan, alginate, sulfated fucan, chitosan, glycosaminoglycan (GAG) and GAG-like polysaccharides. Applications of electrospray ionization mass spectrometry (ESI-MS) are mainly presented and the general applications of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) are also outlined. Some technical challenges in the structural analysis of marine oligosaccharides by MS have also been pointed out.

Cephalopod ink: production, chemistry, functions and applications

One of the most distinctive and defining features of coleoid cephalopods—squid, cuttlefish and octopus—is their inking behavior. Their ink, which is blackened by melanin, but also contains other constituents, has been used by humans in various ways for millennia. This review summarizes our current knowledge of cephalopod ink. Topics include: (1) the production of ink, including the functional organization of the ink sac and funnel organ that produce it; (2) the chemical components of ink, with a focus on the best known of these—melanin and the biochemical pathways involved in its production; (3) the neuroecology of the use of ink in predator-prey interactions by cephalopods in their natural environment; and (4) the use of cephalopod ink by humans, including in the development of drugs for biomedical applications and other chemicals for industrial and other commercial applications. As is hopefully evident from this review, much is known about cephalopod ink and inking, yet more striking is how little we know. Towards closing that gap, future directions in research on cephalopod inking are suggested.

Typing of blood-group antigens on neutral oligosaccharides by negative-ion electrospray ionization tandem mass spectrometry

Blood-group antigens, such as those containing fucose and bearing the ABO(H)- and Lewis-type determinants expressed on the carbohydrate chains of glycoproteins and glycolipids, and also on unconjugated free oligosaccharides in human milk and other secretions, are associated with various biological functions. We have previously shown the utility of negative-ion electrospay ionization tandem mass spectrometry with collision-induced dissociation (ESI-CID-MS/MS) for typing of Lewis (Le) determinants, for example, Le(a), Le(x), Le(b), and Le(y) on neutral and sialylated oligosaccharide chains. In the present report, we extended the strategy to characterization of blood-group A-, B-, and H-determinants on type 1 and type 2 and also on type 4 globoside chains to provide a high sensitivity method for typing of all the major blood-group antigens, including the A, B, H, Le(a), Le(x), Le(b), and Le(y) determinants, present in oligosaccharides. Using the principles established, we identified two minor unknown oligosaccharide components present in the products of enzymatic synthesis by bacterial fermentation. We also demonstrated that the unique fragmentations derived from the D- and (0,2)A-type cleavages observed in ESI-CID-MS/MS, which are important for assigning blood-group and chain types, only occur under the negative-ion conditions for reducing sugars but not for reduced alditols or under positive-ion conditions.

Preparation of water-soluble melanin from squid ink using ultrasound-assisted degradation and its anti-oxidant activity

Water-soluble squid melanin fractions were firstly prepared using ultrasound-assistant degradation method under alkaline condition, which is optimized by response surface methodology. The processing melanin fractions were divided into different molecular weight (Mw) fractions by membrane separation (below 10 kDa, among 10-50 kDa and over 50 kDa). The AFM image and particle-size analysis showed monomer units of the melanin were destroyed, and huge polymers were degraded into smaller soluble particles after ultrasound. While, UV, IR and solid (13)C NMR spectra indicated that the basic structure of melanin fraction was still retained after ultrasound process. Further analysis showed soluble melanin fractions obtained in 0.5 and 1 M NaOH, with Mw above 10 kDa exhibited much higher in vitro antioxidant potency. The IC50 of these fractions (IC50 among 19-80 μg) on scavenging O 2 ∙¯ is more efficient than carnosine (IC50 = 355 μg/ml.), a commercialized antioxidant. They (IC50 mong 115-180 μg/ml) are as efficient as carnosine (IC50 = 110 μg/ml) on scavenging ∙OH. Our research has reported a novel method for preparation of water-soluble melanin fractions from squid ink, which could be a promising free radical scavenger from nature resource.

Enzymatic preparation and structural determination of oligosaccharides derived from sea cucumber (Acaudina molpadioides) fucoidan

Sea cucumber fucoidan is a major bioactive component of sea cucumber. Sea cucumber is widely consumed in East Asian countries as healthy food. Employing the degrading enzyme from the marine bacterium strain Flavobacteriaceae CZ1127, sea cucumber (Acaudina molpadioides) fucoidan oligosaccharides were prepared by enzymatic hydrolysis. The oligosaccharide profile of the hydrolysate was determined by liquid chromatography coupled with mass spectrometry (LC-MS). With the assistance of LC-MS, four major oligosaccharides in the hydrolysate were purified. By using tandem mass spectrometry and nuclear magnetic resonance, delicate structures of the oligosaccharides were verified as α-l-Fucp-1→3-α-l-Fucp(2,4OSO3(2-))-1→3-α-l-Fucp, α-l-Fucp-1→3-α-l-Fucp(2,4OSO3(2-))-1→3-α-l-Fucp-1→3-α-l-Fucp, α-l-Fucp-1→3-α-l-Fucp(2,4OSO3(2-))-1→3-α-l-Fucp-1→3-α-l-Fucp-1→3-α-l-Fucp-1→3-α-l-Fucp(2,4OSO3(2-))-1→3-α-l-Fucp and α-l-Fucp-1→3-α-l-Fucp(2,4OSO3(2-))-1→3-α-l-Fucp-1→3-α-l-Fucp-1→3-α-l-Fucp-1→3-α-l-Fucp(2,4OSO3(2-))-1→3-α-l-Fucp-1→3-α-l-Fucp.

Sequence determination and anticoagulant and antithrombotic activities of a novel sulfated fucan isolated from the sea cucumber Isostichopus badionotus

BACKGROUND

The aim is to analyze the structure, anticoagulant and antithrombotic activities of a sulfated fucan isolated from sea cucumber Isostichopus badionotus (fucan-Ib).

METHODS

Fucan-Ib was hydrolyzed under mild acid conditions. The oligosaccharide fragments were fractionated by gel-filtration chromatography and the structures were determined by negative-ion electrospray tandem mass spectrometry with collision-induced dissociation and two-dimensional NMR. Anticoagulant activities were measured by activated partial thromboplastin, thrombin and prothrombin times, and by in vitro inhibition experiments with factors IIa and Xa. Antithrombotic activities were determined in vitro by measuring the length and weight of the thrombus generated.

RESULT

The linear polysaccharide sequence of fucan-Ib was deduced from the structures of its oligosaccharide fragments produced by acid hydrolysis. Under mild conditions, the glycosidic bonds between the non-sulfated and 2,4-O-disulfated fucose residues were selectively cleaved and highly ordered oligosaccharide fragments with a tetrasaccharide repeating unit [→3Fuc(2S,4S)α1→3Fuc(2S)α1→3Fuc(2S)α1→3Fucα1→]n were obtained. In in vitro assays fucan-Ib showed good anticoagulant and antithrombotic activities compared with heparin and the fucosylated chondroitin sulfate isolated from the same source (fCS-Ib). The two polysaccharides, fucan-Ib and fCS-Ib, differ in the mechanism of action; the former exhibited activity mainly by potentiation of antithrombin acted on thrombin and factor Xa whereas the latter mainly through heparin cofactor II.

CONCLUSION

Fucan-Ib has a well defined structure with tetrasaccharide tandem repeats and good anticoagulant and antithrombotic activities. GENERAL IMPORTANCE: Fucan-Ib has a well defined structure and can be readily quality-controlled, and therefore has potential therapeutic value as an affective antithrombotic drug with low risk of bleeding.