Structure and Metabolically Oriented Efficacy of Fucoidan from Brown Alga Sargassum muticum in the Model of Colony Formation of Melanoma and Breast Cancer Cells

This work reports the detailed structure of fucoidan from Sargassum miticum (2SmF2) and its ability to potentiate the inhibitory effect of glycolysis inhibitor 2-deoxy-d-glucose (2-DG). 2SmF2 was shown to be sulfated and acetylated galactofucan containing a main chain of alternating residues of 1,3- and 1,4-linked α-l-fucopyranose, fucose fragments with monotonous 1,3- and 1,4-type linkages (DP up to 3), α-d-Gal-(1→3)-α-L-Fuc disaccharides, and 1,3,4- and 1,2,4-linked fucose branching points. The sulfate groups were found at positions 2 and 4 of fucose and galactose residues. 2SmF2 (up to 800 µg/mL) and 2-DG (up to 8 mM) were not cytotoxic against MDA-MB-231 and SK-MEL-28 as determined by MTS assay. In the soft agar-based model of cancer cell colony formation, fucoidan exhibited weak inhibitory activity at the concentration of 400 µg/mL. However, in combination with low non-cytotoxic concentrations of 2-DG (0.5 or 2 mM), 2SmF2 could effectively inhibit the colony formation of SK-MEL-28 and MDA-MB-231 cells and decreased the number of colonies by more than 50% compared to control at the concentration of 200 µg/mL. Our findings reveal the metabolically oriented effect of fucoidan in combination with a glycolysis inhibitor that may be beneficial for a therapy for aggressive cancers.

Structure and chemopreventive activity of fucoidans from the brown alga Alaria angusta

Six fucoidan fractions were isolated from the brown alga Alaria angusta. Structures of enzymatic hydrolysis products of the fraction 1AaF2 (Fuc:Gal ~ 1:1; 33 % of sulfates) by fucanase from Wenyingzhuangia fucanilytica were studied by chemical and instrumental (NMR spectroscopy and mass-spectrometry) methods. It was shown that 1AaF2 consisted of two structurally different fucoidans: a sulfated 1,3;1,4-α-L-fucan and an enzyme-resistant sulfated and acetylated complex fucogalactan (Fuc:Gal ~ 1:2; 19 % of sulfates) 1AaF2_HMP containing extended 1,3-linked fucose and 1,3/1,4-linked galactose fragments (up to 5 residues). The fractions 1AaF2 and 1AaF2_HMP were a non-cytotoxic, possessed dose-dependent chemopreventive effect on EGF-induced neoplastic cell transformation of mouse normal epidermal JB6 Cl41 cells and inhibited the colony formation of human melanoma SK-MEL-28 cells.

Determination of the structure and in vitro anticancer activity of fucan from Saccharina dentigera and its derivatives

The fucoidan SdeF was isolated from brown alga Saccharina dentigera. The structure of the obtained polysaccharide was studied by chemical methods, NMR spectroscopy of the fully and partially desulfated derivatives, and mass spectrometry of the fucoidan fragments, labeled with 18O. The SdeF was shown to be sulfated (40%) 1,3-linked α-L-fucan, with branches at C2. The sulfate groups were found at positions C2 and C4. Derivatives SdeFDS and SdeFPL were obtained by solvolytic desulfation and autohydrolysis of SdeF, respectively. According to 13C NMR data, SdeFDS is 1,3-linked α-L-fucan, while SdeFPL is 4-sulfated 1,3-linked α-L-fucan. Native fucoidan SdeF was shown to be a non-toxic anticancer substance in the model of human malignant melanoma RPMI-7951, colorectal adenocarcinoma HCT-116, and small intestine adenocarcinoma HuTu 80 cells. The partial desulfation of SdeF at C2 and/or the reduction of its Mw, from 229 to 28 kDa, decreased the anticancer activity; complete removal of the sulfated groups and/or Mw reduction to 4.7 kDa further reduced the effect of this polysaccharide.

The structure of fucoidan from Sargassum oligocystum and radiosensitizing activity of galactofucans from some algae of genus Sargassum

The aim of this study was to establish the fine structure of fucoidan from Sargassum oligocystum and to study the radiosensitizing effect of fucoidans from three algae of genus Sargassum (S. oligocystum, S. duplicatum, and S. feldmannii) with different structures. The fucoidan SoF2 from S. oligocystum was sulfated (32%) galactofucan (Fuc:Gal = 2:1), with a Mw of 183 kDa (Mw/Mn = 2.0). Its supposed structure was found to be predominantly 1,3-linked fucose as the main chain, with branching points at C2 and C4. The branches could be single galactose and/or fucose short chains with terminal galactose residues. Sulfate groups were found at positions C3, C2, and/or C4 of fucose residues and at C2 and/or C4 of galactose residues. The radiosensitizing effect of galactofucans from S. oligocystum, S. duplicatum, and S. feldmannii against human melanoma SK-MEL-28, colon HT-29, and breast MDA-MB-231 cancer cells was investigated. The influence of all investigated polysaccharides treatments with/without X-ray radiation on colony formation of human melanoma cells SK-MEL-28 was weak. Fucoidan from S. feldmannii has been shown to be the most promising radiosensitizing compound against human colon HT-29 and breast MDA-MB-231 cancer cells.

Composition of polysaccharides and radiosensitizing activity of native and sulfated laminarans from the Tаuуа basicrassa Kloczc. et Krupn

Polysaccharide fractions of alginate, laminarans and fucoidans were obtained from the brown alga Tauya basicrassa. Yields of alginate and laminarans were large (19.7 % and 5.62 %, respectively), whereas the content of fucoidans (0.52 %) was not significant. Alginate and laminarans had typical structures for those substances. Fucoidans were low- and medium-sulfated heterogeneous polysaccharides. The fucoidan fraction 1TbF1 was sulfated fucogalactan containing a backbone from 1,6-linked residues of β-d-galactopyranose with branches at C3 and C4, terminal fucose and galactose residues and fragments from 1,3-; 1,4-; and 1,2-fucose residues. Sulfate groups were found at positions 2 and 4 of fucose, and positions 2, 3 and 4 of galactose residues. Laminaran 2TbL was subjected to a sulfation to obtain the derivative 2TbLS with partial sulfation (46 %) at C2, C4 and C6. It was shown that 2TbL and 2TbLS inhibited colony formation of sensitize-tested colon cancer cells HT-29 and HCT-116 to X-ray radiation.

Fucoidans from brown algae Laminaria longipes and Saccharina cichorioides: Structural characteristics, anticancer and radiosensitizing activity in vitro

The sulfated α-l-fucans ScF and LlF were obtained from brown algae of the Laminariaceae family (Saccharina cichorioides and Laminaria longipes). According to spectroscopy NMR, the LlF fucan predominantly contained the →3)-α-l-Fucp-(2SO3-)-(1→4)-α-l-Fucp-(1→2)-α-l-Fucp-(4SO3-)-(1→ repeating units, with small amounts of disaccharide 1,4-linked fragments and 3-sulfated fucose residues. Mass spectrometric analysis revealed the presence of the following fragments in the fucan structure: α-l-Fucp-(2SO3-)-(1→4)-α-l-Fucp-(2SO3-)-(1→3)-α-l-Fucp-(4SO3-); α-l-Fucp-(2,4SO3-)-(1→3)-α-l-Fucp-(1→3)-α-l-Fucp-(4SO3-); α-l-Fucp-(2SO3-)-(1→2)-α-l-Fucp; α-l-Fucp-(2SO3-)-(1→2)-α-l-Fucp-(4SO3-); α-l-Fucp-(2SO3-)-(1→3)-α-l-Fucp; α-l-Fucp-(2,4SO3-)-(1→3)-α-l-Fucp; α-l-Fucp-(4SO3-)-(1→4)-α-l-Fucp; and α-l-Fucp-(4SO3-)-(1→4)-α-l-Fucp-(2SO3-). Both ScF and LlF fucoidans inhibited colony formation and growth of melanoma and colon cancer cells and sensitize-tested cancer cells to X-ray radiation to a comparable degree.

Comparison of structure and in vitro anticancer activity of native and modified fucoidans from Sargassum feldmannii and S. duplicatum

Fucoidans are valuable biologically active polysaccharides of brown algae. The aim of this study was to investigate the structure of fucoidan from Sargassum feldmannii and the anticancer effects of native and modified polysaccharides from S. feldmannii and S. duplicatum. The structure of sulfated (25.3%) galactofucan SfF2 (Fuc/Gal = 72/28 mol%) from S. feldmannii was investigated by NMR spectroscopy of desulfated derivative and mass spectrometry of fucoidan fragments labelled with 18O. SfF2 was shown to contain the main chain from 1,3-linked α-l-fucopyranose and β-d-galactopyranose residues with fucose branches at C4 and C6 of galactose residues and C2 of fucose residues. The following fragments were also identified in SfF2: Fuc-(1,4)-Fuc, Gal-(1,3)-Gal, and Gal-(1,4)-Gal. The sulfate groups occupied positions C2, C3, and C4 of fucose residues and C2, C3, C4, and C6 of galactose residues. The galactofucans from S. feldmannii, S. duplicatum, and their derivatives exhibited no cytotoxicity in vitro. The native and deacetylated fucoidans (200 μg/mL) inhibited colony formation of human colon cancer cells (DLD-1, HT-29, and HCT-116). Both desulfated fucoidans possessed weak anticancer activity.

Structural characteristics and anticancer activity in vitro of fucoidan from brown alga Padina boryana

The sulfated and acetylated fucoidan fraction, containing fucose, galactose, mannose, glucose and uronic acid residues, was isolated from the brown alga Padina boryana. The structure of galactofucan part was studied after different modifications by NMR spectroscopy and mass spectrometry. It was shown that galactofucan contained the main chain of alternating 1,4-linked α-l-fucopyranose and 1,3-linked β-d-Galactopyranose. Single fucose residues were found as branches at C4 of galactose residues. Also, fucoidan contained 1,3- or 1,4-linked Fuc-Fuc and Gal-Gal fragments. The sulfate groups occupied positions C2, C3 and C4 of both fucose and galactose residues, which was shown by tandem mass spectrometry of fragments, labeled with heavy-oxygen. The anticancer effect of native and modified fucoidan fractions was studied in vitro on the colorectal carcinoma cells DLD-1 and HCT-116. All fucoidans had no cytotoxicity under 400 μg/mL and inhibited colony formation of cancer cells at concentration of 200 μg/mL.

Polysaccharides from brown algae Sargassum duplicatum: the structure and anticancer activity in vitro

The laminaran SdL and fucoidan SdF were isolated from brown algae Sargassum duplicatum. SdL was 1,3;1,6-β-d-glucan (1,3:1,6=6:1) with a main chain, represented by 1,3-linked glucose residues, due to NMR spectroscopy data. Single glucose residues could form branches at C6. Unusual structure of fucoidan SdF was studied by chemical and enzymatic methods, NMR spectroscopy of desulfated and deacetylated polysaccharide and mass spectrometry of fucoidan fragments labeled with 18O. Fucoidan was sulfated (31.7%) and acetylated galactofucan (Fuc:Gal∼1:1) with a main chain of 1,4-linked alternating α-l-fucose and β-d-galactose residues. Side chains were represented by extensive (DP≥5) 1,3-linked 2,4-disulfated α-l-fucose residues with branching points at C2. Fucose residues in the main chain were sulfated at C2 and less at C3, while galactose residues were sulfated at C2, C3, and less at C4, C6. The fucoidan SdF was effective against colony formation of colon cancer cells in vitro.

Engineering of Chimeric Protein Based on E Protein Domain III of Tick- Borne Encephalitis Virus and OmpF Porin of Yersinia pseudotuberculosis

BACKGROUND

Tick-borne encephalitis poses a serious public health threat in the endemic regions. The disease treatment is restricted to symptomatic therapy, so great expectations are in the development of the prophylactic and therapeutic vaccines. The domain III of E protein of the tickborne encephalitis virus is the main antigenic domain which includes virus-specific epitopes recognized by neutralizing antibodies.

OBJECTIVES

The main objective of this study was to design, express, isolate and characterize the chimeric protein based on the fusion of domain III of E protein of the tick-borne encephalitis virus and bacterial porin OmpF from Yersinia pseudotuberculosis.

METHODS

The chimeric gene was obtained by the PCR based fusion method from two fragments containing overlapping linker sequences. Resulting plasmids were transformed into BL21(DE3) pLysS electrocompetent cells for subsequent heterologous protein expression. All recombinant proteins were purified using immobilized metal affinity chromatography under denaturing conditions. The identity of the chimeric protein was confirmed by MALDI-TOF mass spectrometry and immunoblot analysis. The content of antibodies against the EIII protein was estimated in mice blood serum by ELISA.

RESULTS

The bacterial partner protein was used for decreasing toxicity and increasing immunogenicity of antigen. The chimeric protein was successfully expressed by the Escherichia coli cells. The purified protein was recognized with immunoblots by anti-E protein of tick-borne encephalitis virus monoclonal antibodies. Furthermore, the protein was able to elicit antibody response against domain III of E protein in immunized mice.

CONCLUSION

The newly obtained chimeric antigen could be valuable for the development of the preventing tick-borne encephalitis subunit vaccines.

Structural features and anticancer activity in vitro of fucoidan derivatives from brown alga Saccharina cichorioides

A fucoidan ScF from brown alga Saccharina cichorioides was extracted, purified and partially depolymerized by autohydrolysis at 37°C for 24, 48 and 72h. Supernatant (SN) and pellet (PL) fractions were obtained by ethanol precipitation of each sample. Unlike spectral data of ScF, NMR of PL derivatives clearly suggested the structure: 1,3-linked α-l-Fucp-4-OSO3- repeating unit. Molecular weights (MWs) of PL fractions were 30, 26 and 18kDa for 24, 48 and 72h of autohydrolyis, respectively. MALDI-TOFMS, size-exclusion HPLC and carbohydrate polyacrylamide-gel electrophoresis (C-PAGE) indicated a similarity of SN mixtures. They consisted mainly of a polysaccharide part (MW 6kDa, C-PAGE data) with a structure similar to PL components (NMR data) and monosaccharides α-l-Fucp-4-OSO3-, α-l-Fucp-2,4-di-OSO3-. PL fractions exhibited almost identical antiproliferative activity in vitro as native fucoidan, while an SN sample for 72h of autohydrolysis was slightly more active against colony formation of colorectal carcinoma cells HT-29.

The comparison of structure and anticancer activity in vitro of polysaccharides from brown algae Alaria marginata and A. angusta

Laminaran and three fucoidan fractions were obtained from the brown alga Alaria marginata. Alaria angusta, studied earlier by us, has the same polysaccharide composition. Galactofucan AmF3 from A. marginata has a main chain of →3)-α-l-Fucp-(2,4-SO3(-))-(1→residues, similar to galactofucan from A. angusta. However, the structure of the branches in fucoidan AmF3 can differ from those in the fucoidan from A. angusta. The following fragments were identified in AmF3: HexA-(1→2)-Fuc, HexA-(1→2)-Gal, Gal-(1→4)-HexA, Fuc-(1→2)-Gal-6-SO3(-), Fuc-4-SO3(-)-(1→6)-Gal, Gal-(1→2)-Gal-2-SO3(-), Gal-4-SO3(-)-(1 →6)-Gal, Gal-4-SO3(-)-(1→3)-Fuc-(1→3)-Fuc, Fuc-4-SO3(-)-(1→6)-Gal-(1→4)-Gal, Gal-(1→4)-Gal-(1→3)-Fuc, Gal-2-SO3(-)-(1→4)-Gal-(1→4)-Gal, Gal-(1→4)-Gal-6-SO3(-)-(1→2)-Gal. Chains of galactose residues (DP up to 9) were found in AmF3 fucoidan. The laminarans, galactofucans and their derivatives from both algae exhibited no cytotoxicity in vitro. Polysaccharides from A. angusta were more effective against colony formation of HT-29 cells, while those from A. marginata had a greater effect on T-47D cells. Sulfated and desulfated fucoidans possessed weak antitumor activity using SK-MEL-28 cells.

Structure and anticancer activity in vitro of sulfated galactofucan from brown alga Alaria angusta

Laminaran and three fractions of fucoidan were isolated from brown alga Alaria angusta. The laminaran AaL was characterized as a typical 1,3;1,6-β-D-glucan (ratio of bonds 1,3:1,6 = 10:1). Fucoidans AaF1 and AaF2 are sulfated heteropolysaccharides, containing fucose, galactose, mannose and xylose. The fraction AaF3 is sulfated and acetylated galactofucan with the main chain represented by a repeating unit → 3)-α-L-Fucp-(2,4-SO3(-))-(1 →. According the data of methylation analysis, AaF3 contains mainly 1,3-linked fucose, less 1,4-linked and 1,4,6-linked galactose residues. The autohydrolysis (37 °C) of fucoidan AaF3 allowed to obtain selectively 2-desulfaled polysaccharide fraction, built up of fucose only, and low molecular weight (LMW) fraction. The negative-ion tandem mass spectrometry of LMW fraction, further hydrolyzed by acid hydrolysis identified the following fragments: Gal-2-SO3(-)-(1 → 4)-Gal, Gal-4-SO3(-)-(1 → 4)-Gal, Gal-(1 → 2)-Gal-4-SO3(-), Fuc-2-SO3(-)-(1 → 4)-Gal, Gal-2-SO3(-)-(1 → 3)-Fuc-(1 → 3)-Fuc, Fuc-2-SO3(-)-(1 → 3)-Fuc-(1 → 4)-Gal. The laminaran AaL and the fucoidan AaF3 exhibited no cytotoxicity in vitro for HT 29, T-47D, and SK-MEL-28 cell lines. The AaF3 fraction suppressed colony formation of HT 29 and T-47D cells, AaL-only HT 29 cells.

Further studies on structure of fucoidan from brown alga Saccharina gurjanovae

A sulfated galactofucan SgF (MW 123kDa) was purified from the brown alga Saccharina gurjanovae. Polysaccharide was depolymerized by autohydrolysis at 25 and 60°C, and products were studied by mass spectrometry and (13)C NMR spectroscopy. According to results of investigation, the main chain of this polysaccharide is built of a repeating units →3)-α-L-Fucp-(2,4-OSO3(-))-(1→. Fucose chains could be sometimes terminated by (1→3)-linked galactose residues. Shorter (1→4)- and/or (1→6)-linked sulfated galactose chains are attached at positions C-2, C-3 of fucose residues. Sulfate groups can occupy positions C-2 and/or sometimes C-3 of Gal residues, but a sulfation at C-4 of the galactofucan could not be excluded. The SgF-AH25-H preparation (71kDa) was obtained by autohydrolysis of SgF at 25°C, which leaded to a selective desulfation at C-2 and, probably, to a cleavage of galactose chains, since structure of SgF-AH25-H represented a repeating unit →3)-α-l-Fucp-(4-OSO3(-))-(1→, which was definitely established by (13)C NMR spectroscopy. Galactofucan SgF and its derivative SgF-AH25-H exhibited no cytotoxic activity and leaded to about the same colony formation inhibition in colon cancer DLD-1 cells. Hence, structural simplification of SgF by lowering its molecular weight, desulfation at C-2 and removing of galactose residues by autohydrolysis at 25°C did not decrease its anticancer activity. This procedure allows obtaining standardized products which can be used as medical.

Fucoidan Analysis by Tandem MALDI-TOF and ESI Mass Spectrometry

The application of mass spectrometry towards the structural analysis of the most interesting sulfated biopolymers of the brown algae-fucoidans only developed relatively recently. During method development, many problems, both chemical and instrumental, have to be solved. For example, mass spectrometry has a limitation in the analysis of anionic high molecular weight (HMW) polysaccharides because of the labile nature of sulfate groups which cause the polysaccharide to desulfate rather than ionize. Thus, decomposition methods should be developed taking into account the structural features of such a complex and fragile compound. The selection of optimal instrument settings for the electrospray ionization mass spectrometry (ESIMS) and of matrix media for matrix-assisted laser desorption/ionization mass spectrometry (MALDIMS) is also required. When optimal parameters for mass spectrometric analyses are found, the application of these methods to the elucidation of structural features of fucoidans (by studying their fragments) allows researchers to rapidly obtain new and unique data, often impossible to achieve by other techniques. Herein, we describe tandem mass spectrometry of sulfated fucooligosaccharides, obtained by an autohydrolysis technique from structurally different fucoidans.

Rapid mass spectrometric analysis of a novel fucoidan, extracted from the brown alga Coccophora langsdorfii

The novel highly sulfated (35%) fucoidan fraction Cf2 , which contained, along with fucose, galactose and traces of xylose and uronic acids was purified from the brown alga Coccophora langsdorfii. Its structural features were predominantly determined (in comparison with fragments of known structure) by a rapid mass spectrometric investigation of the low-molecular-weight fragments, obtained by "mild" (5 mg/mL) and "exhaustive" (maximal concentration) autohydrolysis. Tandem matrix-assisted laser desorption/ionization mass spectra (MALDI-TOF/TOFMS) of fucooligosaccharides with even degree of polymerization (DP), obtained by "mild" autohydrolysis, were the same as that observed for fucoidan from Fucus evanescens, which have a backbone of alternating (1 → 3)- and (1 → 4) linked sulfated at C-2 and sometimes at C-4 of 3-linked α -L-Fucp residues. Fragmentation patterns of oligosaccharides with odd DP indicated sulfation at C-2 and at C-4 of (1 → 3) linked α -L-Fucp residues on the reducing terminus. Minor sulfation at C-3 was also suggested. The "exhaustive" autohydrolysis allowed us to observe the "mixed" oligosaccharides, built up of fucose/xylose and fucose/galactose. Xylose residues were found to occupy both the reducing and nonreducing termini of FucXyl disaccharides. Nonreducing galactose residues as part of GalFuc disaccharides were found to be linked, possibly, by 2-type of linkage to fucose residues and were found to be sulfated, most likely, at position C-2.

Structure, enzymatic transformation and anticancer activity of branched high molecular weight laminaran from brown alga Eisenia bicyclis

The structure of high molecular weight laminaran from brown alga Eisenia bicyclis was investigated by chemical and enzymatic methods, NMR spectroscopy and mass spectrometry. The laminaran from E. bicyclis was characterized as 1,3;1,6-β-D-glucan with the high content of 1,6-linked glucose residues (ratio of bonds 1,3:1,6=1.5:1), which are both in the branches and in the main chain of the laminaran. The degree of polymerization of fragments, building from 1,3-linked glucose residues with single glucose branches at C-6 or without it, was no more than four glucose residues. The main part of 1,3-linked glucose blocks was builded from disaccharide fragments. 1,6-Linked glucose residues were localized basically on non-reduced ends of molecules. The degree of polymerization of 1,6-linked blocks was not greater than three glucose residues. Laminaran contained laminarioligosaccharides, gentiobiose, gentiotriose and single glucose residues in the branches at the C-6. Laminaran and its products of enzymatic hydrolysis inhibited a colony formation of human melanoma SK-MEL-28 and colon cancer DLD-1 cells. It was shown that decreasing the molecular weight of native laminaran to a determined limit (degree of polymerization 9-23) and increasing the content of 1,6-linked glucose residues increased the anticancer effect. Therefore, they may be perspective antitumor agents.

Isolation of fucoxanthin and highly unsaturated monogalactosyldiacylglycerol from brown alga Fucus evanescens C Agardh and in vitro investigation of their antitumor activity

Fucoxanthin (FX) and highly unsaturated monogalactosyldiacylglycerol (MGDG) were isolated from the ethanol extract of brown alga Fucus evanescens. Their structures were identified by nuclear magnetic resonance, complemented by electrospray ionization mass spectrometry (ESIMS). MGDG was identified as 1-O-(5Z,8Z,11Z,14Z,17Z-eicosapentanoyl)-2-O-(6Z,9Z,12Z,15Z-octadecatetraenoyl)-3-O-β-D-galactopiranosyl-sn-glycerol. Antitumor activity of these compounds was tested on human melanoma (SK-MEL-28) cells. MGDG and FX inhibited the growth of human melanoma cells in a dose-dependent manner. IC50 values for growth inhibition were 104 and 114 μM, correspondently.

Structural characteristics and anticancer activity of fucoidan from the brown alga Sargassum mcclurei

Three different fucoidan fractions were isolated and purified from the brown alga, Sargassum mcclurei. The SmF1 and SmF2 fucoidans are sulfated heteropolysaccharides that contain fucose, galactose, mannose, xylose and glucose. The SmF3 fucoidan is highly sulfated (35%) galactofucan, and the main chain of the polysaccharide contains a →3)-α-L-Fucp(2,4SO₃⁻)-(1→3)-α-L-Fucp(2,4SO₃⁻)-(1→ motif with 1,4-linked 3-sulfated α-L-Fucp inserts and 6-linked galactose on reducing end. Possible branching points include the 1,2,6- or 1,3,6-linked galactose and/or 1,3,4-linked fucose residues that could be glycosylated with terminal β-D-Galp residues or chains of alternating sulfated 1,3-linked α-L-Fucp and 1,4-linked β-D-Galp residues, which have been identified in galactofucans for the first time. Both α-L-Fucp and β-D-Galp residues are sulfated at C-2 and/or C-4 (and some C-6 of β-D-Galp) and potentially the C-3 of terminal β-D-Galp, 1,4-linked β-D-Galp and 1,4-linked α-L-Fucp residues. All fucoidans fractions were less cytotoxic and displayed colony formation inhibition in colon cancer DLD-1 cells. Therefore, these fucoidan fractions are potential antitumor agents.

ESIMS analysis of fucoidan preparations from Costaria costata, extracted from alga at different life-stages

Four fucoidan fractions from brown alga Costaria costata, collected at different life-stages: vegetative, May (5F2 and 5F3) and generative, July (7F1 and 7F2) collections were characterized. It was found that seaweed synthesizes different set of fucoidans - one with high fucose content and substantial percentage of hexoses and uronic acid and lower sulfate content (7F1, 5F2 and 5F3) and other - highly sulfated galactofucan (7F2). Structural features of fractions 7F2 and 5F3 were predominantly determined by mass spectrometric analysis of low-molecular-weight (LMW) oligosaccharide fragments, obtained by autohydrolysis of 7F2 and mild acid hydrolysis of 5F3 fucoidans. It was found that oligosaccharides from 7F2 fractions were mainly built up of sulfated at C-2 and/or at C-2/C-4 (1→3)-linked α-l-fucopyranose residues. d-Galactose residues, sulfated either at C-2 or C-6, were found as parts of mixed di- and trisaccharides at both termini and, probably, internal. Fucose residues in 5F3 fucoidan fragments were sulfated at C-2 and sometimes at C-4. Galactose residues were sulfated at C-4 and less frequently at C-2. Resistant to hydrolysis fraction was probably a core, built up with fucose, mannose and glucuronic acid. Presumably, oligosaccharide fragments were branches at C-4 of GlcA. They were sulfated at C-2 and sometimes at C-4 (1→3)- and/or (1→4)-linked fucooligosaccharides (sometimes terminated with (1→3)-linked galactose) and sulfated at C-4 or C-2 (1→4)- or, probably, (1→6)-linked galactooligosaccharides, probably, with own branches, formed by (1→2)-linked galactose residues. Unsulfated xylose residues were probably terminal in chains built up of fucose. It was confirmed, that monosaccharide content and structure of fucoidans of vegetative algae changed following its life stage. Generative alga in general produced highly sulfated galactofucan having lower MW along with less sulfated mannoglucuronofucan with higher MW, which was extensively synthesized by vegetative algae.

Structural similarities of fucoidans from brown algae Silvetia babingtonii and Fucus evanescens, determined by tandem MALDI-TOF mass spectrometry

Rapid mass spectrometric investigation of oligosaccharides, obtained by autohydrolysis of fucoidans from brown algae Silvetia babingtonii and Fucus evanescens (Fucales, Phaeophyceae) has shown both similarities and differences in structural features/sulfation pattern of their fragments, obtained in the same conditions. Tandem MALDI-TOF MS of fucooligosaccharides with even DP (degree of polymerization) was close to that observed for fucoidan from F. evanescens. Slight differences in tandem mass spectra of fragments with odd DP indicated, probably, sulfation at C-3 (instead of C-2 in F. evanescens) of some (1→4)-linked α-L-Fucp residues and/or the presence of short blocks, built up of (1→3)-linked α-L-Fucp residues.

Investigation of a sulfate transfer during autohydrolysis of a fucoidan from the brown alga Fucus evanescens by tandem ESIMS

A fucoidan from the brown alga Fucus evanescens was effectively depolymerized by autohydrolysis. Negative-ion electrospray ionization mass spectrometry (ESIMS) revealed that the mixture contained sulfated mono- and oligosaccharides with polymerization degree (DP) up to 6, having from 1 to 4 sulfate groups per molecule. The prevalence of oligosaccharides with even DP was observed. It could be explained by the tendency of the 3-linked α-L-fucopyranose residues to hydrolyze faster than 4-linked ones. The intermolecular sulfate transfer during autohydrolysis was detected by ESIMS, when equimolar quantities of D-Rib and D-Glc were added as acceptors. The products were singly-sulfated and hexose was about four times more effective as an acceptor, than pentose. It was impossible to record MS/MS spectra of the sulfate transfer products, since intensities of their ions were too low.

Structural analysis of a highly sulfated fucan from the brown alga Laminaria cichorioides by tandem MALDI and ESI mass spectrometry

Water-soluble polysaccharide fractions were extracted from the brown alga Laminaria cichorioides. Samples were collected monthly from May to October in Troitsa Bay (Japan Sea, Russia). Analysis showed that the content and monosaccharide composition of the fractions changed with the collection season. Fucoidan was isolated and purified from the most fucose-rich fraction, collected in July, and subjected to autohydrolysis to obtain fucooligosaccharides, suitable for mass-spectrometric analysis. Both ESIMS and MALDI-TOFMS analyses show that multisulfated (up to 3) fucooligosaccharides with polymerization degree n from 2 to 5, including mono- and disulfated-fucose residues, were the major products of autohydrolysis. The structural features of the fucooligosaccharides and their alditol derivatives were elucidated by tandem MALDI-TOFMS and ESIMS. The results obtained allowed us to conclude that fragments of the fucoidan, collected in July, were predominantly linked with a (1→3)-type of linkage and that sulfate groups occupied mostly C-2 or C-2/C-4 of the α-l-fucose residues.

Structural analysis of a fucoidan from the brown alga Fucus evanescens by MALDI-TOF and tandem ESI mass spectrometry

A fucoidan, a heterogeneous sulfated polysaccharide from the brown alga Fucus evanescens, was depolymerized under solvolytic conditions, and its ethanol-extracted low-molecular-weight fraction was analyzed by MALDI-TOFMS and ESIMS/MS. It was found that the mixture contained unsulfated oligosaccharides including some monosulfated components, which were shown to consist of mainly (1-->3)-linked 2-O-sulfonated fucose residues (from 1 to 4). Minor components of the mixture were shown to contain 2-O- and 4-O-sulfonated xylose and galactose residues. Among them, mixed monosulfonated fucooligosaccharides were detected and characterized: Xyl-(1-->4)-Fuc, Gal-(1-->4)-Fuc, Gal-(1-->4)-Gal-(1-->4)-Fuc, Gal-(1-->4)-Gal. Fucose, galactose, and xylose residues were shown to be mainly 2-O-sulfonated with traces of 4-O-sulfonation. Glucuronic acid was also found as a part of non-sulfated fucooligosaccharides: Fuc-(1-->3)-GlcA, Fuc-(1-->4)-Fuc-(1-->3)-GlcA, Fuc-(1-->3)-Fuc-(1-->4)-Fuc-(1-->3)-GlcA.

Triterpene glycosides from Antarctic sea cucumbers. 2. Structure of Achlioniceosides A(1), A(2), and A(3) from the sea cucumber Achlionice violaecuspidata (=Rhipidothuria racowitzai)

Three new triterpene glycosides, achlioniceosides A(1) (1), A(2) (2), and A(3) (3), have been isolated from the Antarctic sea cucumber Achlionice violaecuspidata. The glycoside structures were elucidated using extensive NMR spectroscopic analysis including one-dimensional (1)H and (13)C spectra, (1)H-(1)H-COSY, HMBC, HMQC, and NOESY and mass spectrometry. Gycosides 1-3 are disulfated pentaosides that are branched at the first xylose residue. The sulfates are attached to C-6 of the glucose residues. Glycosides 1-3 are the first triterpene glycosides isolated from a sea cucumber belonging to the order Elasipodida.

Triterpene glycosides from Antarctic sea cucumbers. 1. Structure of liouvillosides A1, A2, A3, B1, and B2 from the sea cucumber Staurocucumis liouvillei: new procedure for separation of highly polar glycoside fractions and taxonomic revision

Five new triterpene glycosides, liouvillosides A1 (1), A2 (2), A3 (3), B1 (4), and B2 (5), have been isolated from the Antarctic sea cucumber Staurocucumis liouviellei along with the known liouvilloside A(6), isolated earlier from the same species, and hemoiedemosides A (7) and B (8), isolated earlier from the Patagonian sea cucumber Hemioedema spectabilis. The isolation was carried out using a new chromatographic procedure including application of ion-pair reversed-phase chromatography followed by chiral chromatography on a cyclodextrin ChiraDex column. The structures of the new glycosides were elucidated using extensive NMR spectroscopy (1H and 13C NMR spectrometry, DEPT, 1H-(1)H COSY, HMBC, HMQC, and NOESY), ESI-FTMS, and CID MS/MS, and chemical transformations. Glycosides 1-3 are disulfated tetraosides and glycosides 4 and 5 are trisulfated tetraosides. Glycosides 2 and 3 contain 3-O-methylquinovose, found for the first time as a natural monosaccharide in sea cucumber glycosides. On the basis of analyses of glycoside structures a taxonomic revision is proposed.

Isolation and characterization of a low-molecular-weight immunoglobulin-binding protein from Yersinia pseudotuberculosis

A low-molecular-weight immunoglobulin-binding protein (IBP) bound with the cell envelope has been isolated from Yersinia pseudotuberculosis cells and partially characterized. This IBP is a hydrophilic protein with a high polarity index of 55.3%. The molecular weight of the protein has been determined by MALDI-TOF mass spectrometry as 14.3 kD. CD spectroscopy showed that the IBP has high contents of the beta-structure and random coil structure. The IBP contains glycine as the N-terminal amino acid. The protein can be stored for a long time at acidic pH values but aggregates and loses activity at alkaline and neutral pH. The IBP binds rabbit IgG with optimum at pH of 6.0-7.5. The IBP interacts with IgG molecule in the Fc-fragment region. The protein retains activity after heating at 100 degrees C in the presence of SDS.