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 ß-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.

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 ß-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 ß-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.

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.

New Aminonaphthoquinone from the Sea Urchins Strongylocentrotus pallidus and Mesocentrotus nudus.

The aminonaphthoquinone, spinamine E (5), was isolated for the first time from the sea urchins Strongylocentrotus pallidus (Sars G.O., 1872) and Mesocentrotus nudus (A. Agassiz, 1864). The structure of 5 was elucidated as 2-amino-3,5,6,7,8-pentahydroxy-1,4-naphthoquinone using ID 1H-, 13C- and 2D NMR procedures, and HR-ESI mass-spectrometric data of 5 and its trimethyl ether. Spinamine E, as well as two other aminonaphthoquinones of sea urchins, echinamines A (2) and B (3), along with their hydroxylated analogues, spinochrome E (4) and echinochrome A (1), were tested for their ability to scavenge the stable DPPH radical and to inhibit lipid peroxidation. All investigated naphthoquinones obtained from the sea urchins showed a high antiradical activity, which was up to 1.5 times higher than that of α-tocopherol. Echinamine B showed the highest scavenging effect (EC50 = 6.5-10(-6) M); this effect decreases in the series 3>5>1>2>4>α-tocopherol. In a lipid peroxidation inhibition testing model, echinamine B and spinamine E showed the highest inhibitory effect. The stability of compounds 1-5 in weakly alkaline solutions was evaluated.

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.

Changes of major carotenoids in gonads of sea urchins (Strongylocentrotus intermedius and S. nudus) at maturation.

Changes in the carotenoid content in gonads of two sea urchins species were investigated during maturation. The content of echinenones and carotenes, the two major carotenoid fractions in gonads, is highest for Strongylocentrotus intermedius at the spawning gametogenic stage of gonad maturation for both sexes. For S. nudus, the content of these pigments is highest at stages of active gametogenesis and spawning for males and at the growth stage for females. A comparison of the carotenoid content dynamics during maturation of gonads for males, females and animals at the resting (sexual inactivity) stage was also carried out.