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P-selectin has been shown to enhance growth and metastasis of mouse tumors by promoting regulatory T cell (Treg) infiltration into the tumors. Theoretically, a P-selectin antagonist could suppress the process. Popylene glycol alginate sodium sulfate (PSS) is a heparin-like marine drug, which was originally approved to treat cardiovascular disease in China. Previously, we reported that PSS was an effective P-selectin antagonist in vitro. However, it is unknown whether PSS can regulate Treg infiltration and its effect on lung metastasis in vivo. Our results showed that PSS at 30 mg/kg significantly suppressed lung metastasis and improved overall survival, with potency comparable to the positive control LMWH. Mechanistic study indicated that PSS blocked tumor cells adhesion and activated platelets by directly binding with activated platelet's P-selectin. Compared to the model group, PSS decreased the percent of Tregs by 63 % in lungs after treating for 21 days while increasing CD8+ T cells (1.59-fold) and Granzyme B+ CD8 T cells (2.08-fold)' percentage for generating an adaptive response for systemic tumor suppression. The study indicated that the P-selectin antagonist, PSS, suppressed lung metastasis by inhibiting the infiltration of regulatory T cells (Treg) into the tumors., Competing Interests: Declaration of competing interest The authors declare that they have no competing financial interests to disclose., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The substituents and backbones are two main factors affecting immune activities of polysaccharides. In the present study, we firstly evaluated the immunostimulating effects of phosphorylated, sulfated, H-phosphonated and nitrated derivatives of low-molecular-weight polymannuronate (LPM) and polyguluronate (LPG) on splenocytes and peritoneal macrophages in vitro. The results showed that the phosphate group was the best substituent to enhance the immune activities, and LPG phosphate (LPGP) had much better activity than LPM phosphate (LPMP). Further studies showed that LPGP not only promoted the proliferation of mouse splenocytes in the presence of either LPS or Con A, but also acted as an excellent peritoneal macrophage activator to enhance the cell phagocytosis, energy metabolism, cytokines release and activities of intracellular enzymes. The studies in RAW264.7 cells revealed that LPGP activated the TBK1-IκBα-NF-κB and the TBK1-IRF3 pathway. Moreover, LPGP rescued the immune response in the Cyclophosphamide-treated mice in vivo. In conclusion, LPGP is a potential alginate-based biological response modifier (BRM)., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Pyrazinopyrimidine-type alkaloids bearing a pyrazino[1,2-a] pyrimidine moiety, often have different functional groups substituted at C-8' or C-2'/C-8', generally further forming unique spiro-/conjugated ring systems. Four undescribed pyrazinopyrimidine-type alkaloids, including three natural products pyrasplorines A-C and an artifact deg-pyrasplorine B, as well as a biogenetically related versicoloid A were discovered from the extract of a mangrove-derived fungus Apergillus verisicolor HDN11-84. Pyrasplorine A contains unique spiral-type skeleton (composed of cyclopentenone ring with the pyrazino[1,2-a] pyrimidine core) which is unprecedented in pyrazinopyrimidine-type alkaloids. The deg-pyrasplorine B could be spontaneously converted from pyrasplorine B in mild conditions. Their structures including absolute configurations were elucidated based on NMR spectroscopic analysis, computational calculations and Marfey's method. The absolute configuration of versicoloid A was re-assigned in this study. All the isolated compounds are non-cytotoxic and deg-pyrasplorine B showed anti-influenza A virus H1N1 activity with the IC 50 of 50 μM., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Marine green algae are valuable sources of diverse health-promoting bioactive components. Ulvan is suitable for biological applications due to its unique structure and numerous bioactivities. Here, the complex structure of ulvan from Ulva pertusa was analyzed using specific ulvan lyase degradation, MS, and NMR detection. Its structure mainly consists of →4)-β-d-GlcA-(1 → 4)-α-l-Rha3S-(1 → and →4)-β-d-Xyl-(1 → 4)-α-l-Rha3S-(1 → repeating units. Small amounts of →4)-α-l-IdoA-(1 → 4)-α-l-Rha3S-(1 → unit also exist. In addition, a minor number of branches, a single GlcA, and a long branch containing GlcA-Glc were linked to Rha3S. The antiviral activity of the ulvan and its degraded fragments were further investigated. Ulvan (1068.2 kDa) and ulvan-F1 (38.5 kDa) with relatively high molecular weight showed potency of inhibiting the infection and replication of vesicular stomatitis virus (VSV) at 100 μg/mL, the inhibition rate of VSV replication was 40.75% and 40.13%, respectively. These results indicated that ulvan has potential as a functional agent., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Bacterial exopolysaccharides (EPSs) are widely applied in food, cosmetic, and medical industries. The EPS produced by Phyllobacterium sp. 921F was a novel polysaccharide, which exhibits attractive characteristics of high yield, favorable rheological properties, and excellent moisture retention ability. Considering the complexity of polysaccharide structures, specific enzymatic hydrolysis was employed here to resolve the structure of the EPS. End-products including tetra-, hexa- and octa-saccharides were isolated. According to their mass spectroscopy (MS) and nuclear magnetic resonance (NMR) spectra, the backbone of the EPS was found to be mainly comprising a → 4)-β-d-Glcp-(1 → 3)-α-d-Galp(4,6-S-Pyr)-(1 → disaccharide repeating units. Based on atomic force microscopy results, EPS exhibited characteristics that were consistent with a stiff, elongated molecule with no branches. The length and height of the single molecular chain were approximately 600 and 0.7 nm, respectively. Our clarification of structure and molecular morphology of EPS from Phyllobacterium sp. 921F provide a foundation for the industrial application of this potential moisture-retaining material., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Cardiovascular disease (CVD) is the No. 1 cause of death worldwide. Hyperlipidemia is one of the major risk factors for CVD. Maintaining lipid homeostasis is an effective way to prevent CVD. We prepared propylene glycol guluronate sulfate (PGGS), a sulfated polysaccharide, and investigated its effect on lipid metabolism in HepG2 cells. We found that total cholesterol (TC) and triglycerides (TG) were significantly decreased in the cells after PGGS treatment. We have also shown that the AMPK signaling is activated after PGGS treatment as evidenced by changes in the expression of many AMPK downstream targets including SREBP-1c, SIRT-1, CPT1, PPARα, and FAS. Our results have demonstrated that PGGS is a potentially novel lipid-lowering agent for CVD prevention., (Copyright © 2018. Published by Elsevier B.V.)

An accurate, rapid, and cost-effective methodology for enzyme assay is highly demanded to screen the effect of compounds on target at the molecular level. Thrombin (EC 3.4.21.5) and factor Xa (FXa, EC 3.4.21.6) have been identified as the critical targets for the development of potential drugs with anticoagulant activity. In this study, a rapid, sensitive and accurate assay based on UHPLC-MS/MS method has been developed for inhibitor screening against thrombin and factor Xa simultaneously. For thrombin and factor Xa, the Michaelis-Menten constants (K m ) were calculated to be 6.14 and 57.27 μM, respectively. The inhibition constants (K i ) for two known inhibitors, argatroban and rivaroxaban, were determined to be 16.23 and 0.41 nM, respectively. The assay was further validated through the determination of a high Z' factor value of 0.89. Finally, the developed assay was applied to screen a chemical library against two enzymes. Three hit compounds belonging to a class of sulfated polysaccharides were identified and their targets of inhibition action were further evaluated. The results indicated that the dual-target assay by UHPLC-MS/MS analysis could be used as a reliable method for screening anticoagulant agents., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A new strain bacteria was isolated and named as Phyllobacterium sp. 921F, due to its high production capacity of exopolysaccharide (EPS). Characterization of physico-chemical properties of the EPS and optimization for high production were conducted to aim at industrial applications. The optimum pH and temperature were 7.0 and 30°C, respectively. The following scale-up fermentation was carried out in 30L bioreactor and amounts of EPS (21.9g/L) were produced. The EPS with a molecular mass of 1082kDa was composed of glucose, galactose, and pyruvate. The EPS solution behaved as Newtonian at low concentrations (≤0.3%) and as shear thinning at higher concentration (e.g, 1%). The moisture retention ability of the EPS was found to be superior to hyaluronic acid. Results suggest that Phyllobacterium sp. 921F is a good candidate for large-scale production of the EPS which might be utilized in food and cosmetics industries., (Copyright © 2017 Elsevier B.V. All rights reserved.)

An extracellular chondroitinase ABC (ChSase ABC, EC 4.2.2.4) produced by cultivating Acinetobacter sp. C26, was purified to homogeneity from the supernatant by ammonium sulfate fractionation, Q-Sepharose Fast Flow and Sephadex G-100 chromatography. The 76kDa enzyme was purified 48.09-fold to homogeneity with specific activity of 348.64U/mg, Using the chondroitin sulfate A (CS-A) as substrate, the maximal reaction rate (Vmax) and Michaelis-Menten constant (Km) of ChSase ABC were found to be 10.471μmol/min/ml and 0.105mg/ml, respectively. The enzyme showed the highest activity at the optimal conditions of pH 6.0 and 42 ∘C, respectively. This enzyme was stable at pH 5-10, 5-9 and 5-7 at 4°C, 37°C and 42°C, respectively. Investigation about thermal stability of ChSase ABC displayed that it was stable at 37°C. ChSase ABC activity was increased in presence of Na + , K + , Mn 2+ , 1,10-phenanthrolin and strongly inhibited by Cu 2+ , Hg 2+ , Al 3+ and SDS. These properties suggested that ChSase ABC from Acinetobacter sp. C26 bring promising prospects in medical and industry applications., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Two different degradases from Alteromonas sp. A321 for polysaccharides from Enteromorpha prolifera (DPE-L and DPE-P) were purified to homogeneity. The molecular weights of purified DPE-L and DPE-P were 75.2 and 102.5 kDa, respectively, and their internal sequences were analysed by LC-MS-MS. The enzymes exhibited an optimum temperature of 30-40 °C (DPE-L) and 35-45 °C (DPE-P), an optimum pH of 7.0 (DPE-L) and 6.0 (DPE-P). DPE-P was highly stable in the presence of EDTA and 1,10-phenanthroline while DPE-L was inhibited by 1,10-phenanthroline. The Km values of DPE-L and DPE-P were 2.93 mg/ml and 0.31 mg/ml and the Vmax values were 6.11 μmol/min/ml and 2.88 μmol/min/ml, respectively. Results of HPLC and ESI-MS analyses showed that enzymatic products were: Rha1(SO3H)1, Rha1(SO3H)1Gluc1, Rha2(SO3H)2Gluc1, and Rha3(SO3H)3Gluc1Xyl1 by DPE-L, and Glu2, Glu3, plus Glu4 by DPE-P, respectively. Thus DPE-L and DPE-P can be used to produce oligosaccharides which potentially revealed more of structure of polysaccharides from E. prolifera., (Copyright © 2016. Published by Elsevier B.V.)

Gypenoside LVI and gypenoside XLVI are the major bioactive dammarane saponins from Gynostemma pentaphyllum. Gypenoside LVI, gypenoside XLVI, and their metabolite 2α-OH-protopanaxadiol (2α-OH-PPD) possess potent non-small cell lung carcinoma A549 cell inhibitory activity. A sensitive liquid chromatography tandem mass spectrometry method was developed and validated to study the pharmacokinetics of gypenoside LVI and XLVI, 2α-OH-PPD, metabolite 1 (M1), and metabolite 2 (M2) after administration of gypenosides or 2α-OH-PPD. Plasma samples from rats were protein precipitated with methanol. Analytes were detected by triple quadrupole MS/MS with an electrospray ionization source in the positive multiple reaction monitoring mode. The transition m/z 441.4→109.2 was selected to quantify gypenoside LVI and XLVI, and 2α-OH-PPD, because of the extensive conversion of the gypenosides to aglycone in the ionization source. M1 and M2 are isomers that shared the transition m/z 493.4→143.1. To avoid interference, the baseline separation of each analyte was performed on a SunFire C18 column with a gradient of acetonitrile (0.1% formic acid, v/v) and water (0.1% formic acid, v/v). The chromatographic run time was 10min. The linearity was validated over a plasma concentration range from 2.00 to 2000ng/mL for M1 and M2, and from 10.0 to 2000 for gypenosides LVI and XLVI, and 2α-OH-protopanaxadiol. The lower limits of quantification were 10.0, 10.0, 10.0, 2.00, and 2.00ng/mL for gypenoside LVI, gypenoside XLVI, 2α-OH-PPD, M1, and M2, respectively, with acceptable intra-/inter-day precision and accuracy. The extraction recovery rates were >86.9% for each compound. No apparent matrix effect or instability was observed during each step of the bioanalysis. After full validation, this method was proved to be simple, fast, and efficient in analyzing large batches of plasma samples for the analytes., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The aim of this study was to assess the effects of purified polymannuronate (PM) obtained from marine brown algae on the performance, antioxidant capacity, immune status, and cecal fermentation profile of broiler chickens. In a 42 d experiment, 540 (average BW 43.77±1.29 g) 1-d-old Arbor Acres male broilers were randomly divided into 5 treatments with 6 replicates of 18 chicks and fed a corn and soybean meal (SBM)-based diet supplemented with 0, 1, 2, 3, or 4 g/kg polymannuronate. Adding polymannuronate to the broiler chickens' diets resulted in a significantly increased ADG and improved feed conversion compared with the control treatment. From d 1 to 42, the ADG of broilers fed 1, 2, 3, or 4 g/kg of polymannuronate was increased by 2.58, 4.33, 4.20, and 3.47%, respectively. Furthermore, parameters related to immune status, antioxidant capacity, and composition of the cecal microflora in broiler chickens fed the polymannuronate-containing diets were altered compared with broiler chickens fed a diet without polymannuronate. Supplementation with polymannuronate significantly increased the concentrations of lactic acid and acetic acid in the cecum compared with the control group. The results indicate that polymannuronate has the potential to improve broiler chicken immune status, antioxidant capacity, and performance., (© 2015 Poultry Science Association Inc.)

Eight new aminomannoglycerolipids (2a-h) with linear, branched, or aromatic acyl chains were synthesized and evaluated for their anti-influenza A virus (IAV) activity. By comparing six mannosyl donors with different protecting and leaving groups, the critical glycosylation reaction employed mannosyl trichloroacetimidate with 2-O-benzoyl protecting group as the donor to give the glycoside with absolute α-anomeric selectivity. The bioactivity results showed that the branched compound 2g could effectively inhibit IAV multiplication in MDCK cells with IC50 69.9μM., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Three derivatives of polymannuronic acid (PM) were prepared by chemically polyanionic modification. PM was substituted with phosphate (OPO3(2-)), H-phosphonate (OPO2H(-)) and sulfate (OSO3(-)) groups with the degree of substitution (DS) of 0.41, 1.42 and 1.04, respectively. The structures of all PM derivatives were characterized by FT-IR, (31)P NMR and (13)C NMR spectroscopy. The weight average molecular weight (Mw) was determined by high performance gel permeation chromatography (HPGPC). The antioxidant activities of PM and its derivatives were evaluated in vitro. The results indicated that both phosphate and H-phosphonate groups improved the hydroxyl radical scavenging activity, while sulfate group enhanced the superoxide radical scavenging activity. However, all of the derivatives scavenged DPPH less effectively than PM. The mechanism for how the different anionic substituent groups influenced the antioxidant activities was discussed., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Aminoglycoglycerolipid 1a isolated from an algal extract showed activity against the enzyme Myt1 kinase with an IC50 value of 0.12 μg/mL. Its analogues, 6'-acylamido-6'-deoxy-α-D-galactoglycerolipids (2a-g) were synthesized in an efficient way with high stereoselectivity. The key step was to employ a 4-OAc protecting group of the galactosyl donor 14 as a remote neighboring participation group to give the glycoside with high α-anomeric selectivity (α:β=32:1) in the glycosylation. The preliminary bioactivity screening showed that compound 2g exhibited good inhibition against Myt1 kinase., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Guluronic acid oligosaccharides (GOS) with degree of polymerization (DP) ranging from 1 to 10 were prepared by a rapid microwave degradation method. Polyguluronic acid, fractionated from alginate hydrolysate, was dissolved in dilute ammonia water at a concentration of 20 mg/mL (pH 5) and then hydrolyzed under microwave irradiation (1600 W) at 130°C for 15 min to produce GOS mixture. The GOS mixture was separated by a Bio-Gel P6 column and ten fractions were obtained. Each GOS fraction was further characterized by electrospray ionization mass spectrometry, (1)H NMR, (13)C NMR, and 2D NMR spectroscopy techniques. The data showed that the GOS fractions were saturated oligoguluronates with general molecular formula C(6n)H(8n+2)O(6n+1) (n=1-10). This microwave degradation method was not only convenient, less time consuming, and environment-friendly, but also produced GOS with high yield (71%) and eliminating a desalting procedure compared to conventional acid hydrolysis method., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

A glycoglycerolipid 1a isolated from a marine alga showed inhibition to Myt1 kinase with IC(50) of 0.12 μg/mL. We synthesized 1a and its seven analogues (1b-h) in an efficient method with high stereoselectivity. The process employed trichloroacetimidate donor 4b at low substrate concentration to achieve high α-selectivity (α/β=33:1) in glycosylation reaction. The present synthesis provided various acyl derivatives required for the study on the structure-activity relationship later., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Alginate lyase which was purified from the fermentation solution of marine bacteria Pseudomonas sp. HJZ216 was applied to hydrolyze algae alginate. Six oligosaccharides, including di- and trisaccharides, were isolated and purified through anion exchange chromatography. The oligosaccharide structures were elucidated based on electrospray ionization-mass spectrometry (ESI-MS) and 2D NMR spectra analysis., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Chlorogenin 3-O-beta-chacotrioside (1) and its 6alpha-O-acyl derivatives (2-6) were concisely synthesized. Introduction of a hydroxyl or acyloxy group onto the C-6 of the steroidal aglycone of dioscin decreased significantly the cytotoxicity of the parent saponin (dioscin).

Fifteen steroids were isolated from the soft coral Dendronephthya sp., of which five are determined as new compounds, namely (22E)-3-O-beta-formylcholest-5,22-diene (1), (22E)-3-O-beta-formyl-24-methyl-cholest-5,22-diene (2), 2-ethoxycarbonyl-2-beta-hydroxy-A-nor-cholest-5-ene-4-one (3), (22E)-2-ethoxycarbonyl-2-beta-hydroxy-A-nor-cholest-5,22-diene-4-one (4), and (22E)-2-ethoxycarbonyl-2-beta-hydroxy-24-mthyl-A-nor-cholest-5,22-diene-4- one (5). 1 and 2 belonged to 3-O-formylated cholesterol analogues, and 3 to 5 are unique ring A-contracted steroids. Their structures were elucidated by extensive 2D NMR in association with IR, MS analysis.

Two new complexes [Cu(N,N',N"-(D-Glc)3-tren)Cl]Cl (1) and [Cu(N,N',N"-(maltose)-tren)]Cl2.H2O (2), have been synthesized and characterized by elementary analysis, and the IR and UV spectra suggest that complex 1 and complex 2 are arranged in trigonal bipyramidal configuration and square-pyramidal configuration, respectively. The crystal structure of complex 1 has been determined by X-ray diffraction as: a = 9.3476(8), b = 17.4236(13), c = 9.7836(8) angstroms, beta = 91.197 degrees, and V = 1593.1(2) Angstroms3, Z = 2, and R = 0.0325, which shows that three secondary amine groups (N-1, N-2, N-3) of the glycosylamine ligand forms the equatorial plane, and the tertiary amine (N-4) and one Cl- are located at the apical positions.

3-O-beta-Chacotriosyl-26-O-beta-D-glucopyranosyl-(25R)-furost-5-en (1), a mimic of the antitumor active proto-dioscin, was concisely synthesized from diosgenin in a linear nine steps and in 17% overall yield. Its congeners with a alpha-l-rhamnopyranosyl, beta-lactosyl, or without a substituent at the 26-OH (13-15) were also prepared. Compound 1, as well as 13-15, did not show any inhibition against tumor cells, implying that proto-dioscin might be also inactive, but readily converted into the antitumor active dioscin.

Alginate that was purified from the fermentation solution of marine bacteria Vibro sp. 510 under specific reaction conditions was hydrolyzed by alginate lyase. Seven oligosaccharides, including di-, tri- and tetrasaccharides, were isolated through low-pressure, gel-permeation chromatography (LP-GPC) and semipreparative strong-anion exchange (SAX) fast-protein liquid chromatography (FPLC). The oligosaccharide structures were elucidated based on ESIMS and 2D NMR spectral analysis. The hydrolytic specificity of this alginate lyase to alginate is discussed., (Copyright 2004 Elsevier Ltd.)

The Ugi four-component reaction (U-4CR) was utilized to prepare divalent and trivalent cluster mannosides with different scaffolds. The glycoclusters obtained were tested for their relative inhibitory potency against the binding of yeast mannan to concanavalin A by solid-phase enzyme-linked lectin assays (ELLA) using methyl alpha-D-mannopyranoside as a standard. Among them, a divalent mannoside containing aromatic groups showed the strongest binding affinity to concanavalin A.

Oligosaccharides were prepared through mild hydrochloric acid hydrolysis of kappa-carrageenan from Kappaphycus striatum carrageenan. Three oligosaccharides were purified by strong-anion exchange high-performance chromatography. Their structure was elucidated using mass spectral and NMR data. Negative-ion electrospray ionization (ESI) mass spectra at different fragmentor voltages provided the molecular weight of the compounds and unraveled the fragmentation pattern of the kappa-carrageenan oligosaccharides. 2D NMR techniques, including 1H-(1)H COSY, 1H-(1)H TOCSY and 13C-(1)H HMQC, were performed to determine the structure of a trisulfated pentasaccharide. 1D NMR and ESIMS were used to determine the structures of a kappa-carrageenan-derived pentasaccharide, heptasaccharide, and an undecasaccharide. All the oligosaccharides characterized have a 4-O-sulfo-D-galactopyranose residue at both the reducing and nonreducing ends.