Glycosaminoglycans from the Starfish Lethasterias fusca: Structures and Influence on Hematopoiesis.

Crude anionic polysaccharides extracted from the Pacific starfish Lethasterias fusca were purified by anion-exchange chromatography. The main fraction LF, having MW 14.5 kDa and dispersity 1.28 (data of gel-permeation chromatography), was solvolytically desulfated and giving rise to preparation LF-deS with a structure of dermatan core [→3)-ß-d-GalNAc-(1→4)-α-l-IdoA-(1→]n, which was identified according to NMR spectroscopy data. Analysis of the NMR spectra of the parent fraction LF led to identification of the main component as dermatan sulfate LF-Derm →3)-ß-d-GalNAc4R-(1→4)-α-l-IdoA2R3S-(1→ (where R was SO3 or H), bearing sulfate groups at O-3 or both at O-2 and O-3 of α-l-iduronic acid, as well as at O-4 of some N-acetyl-d-galactosamine residues. The minor signals in NMR spectra of LF were assigned as resonances of heparinoid LF-Hep composed of the fragments →4)-α-d-GlcNS3S6S-(1→4)-α-l-IdoA2S3S-(1→. The 3-O-sulfated and 2,3-di-O-sulfated iduronic acid residues are very unusual for natural glycosaminoglycans, and further studies are needed to elucidate their possible specific influence on the biological activity of the corresponding polysaccharides. To confirm the presence of these units in LF-Derm and LF-Hep, a series of variously sulfated model 3-aminopropyl iduronosides were synthesized and their NMR spectra were compared with those of the polysaccharides. Preparations LF and LF-deS were studied as stimulators of hematopoiesis in vitro. Surprisingly, it was found that both preparations were active in these tests, and hence, the high level of sulfation is not necessary for hematopoiesis stimulation in this particular case.

The Distribution of Asterosaponins, Polyhydroxysteroids and Related Glycosides in Different Body Components of the Far Eastern Starfish Lethasterias fusca.

Glycoconjugated and other polar steroids of starfish have unique chemical structures and show a broad spectrum of biological activities. However, their biological functions remain not well established. Possible biological roles of these metabolites might be indicated by the studies on their distribution in the organism-producer. In order to investigate the localization of polar steroids in body components of the Far Eastern starfish Lethasterias fusca, chemical constituents of body walls, gonads, stomach, pyloric caeca, and coelomic fluid were studied by nanoflow liquid chromatography/mass spectrometry with captive spray ionization (nLC/CSI-QTOF-MS). It has been shown that the levels of polar steroids in the studied body components are qualitatively and quantitatively different. Generally, the obtained data confirmed earlier made assumptions about the digestive function of polyhydroxysteroids and protective role of asterosaponins. The highest level of polar steroids was found in the stomach. Asterosaponins were found in all body components, the main portion of free polyhydroxysteroids and related glycosides were located in the pyloric caeca. In addition, a great inter-individual variability was found in the content of most polar steroids, which may be associated with the peculiarities in their individual physiologic status.

Structural Characterization of Polar Steroid Compounds of the Far Eastern Starfish Lethasterias fusca by Nanoflow Liquid Chromatography Coupled to Quadrupole Time-of-Flight Tandem Mass Spectrometry.

Nanoflow liquid chromatography coupled with a captive spray ionization time-of-flight tandem mass spectrometer (nLC/CSI-QTOF-MS/MS) was used in the structural determination of polar steroid compounds of starfish Lethasterias fusca. A total of 207 compounds including 106 asterosaponins, 81 glycosides of polyhydroxysteroids, and 14 polyhydroxylated steroids were detected and characterized by MS and MS/MS. Twenty compounds among them were unambiguously identified using authentic standard compounds, isolated earlier from this and other starfish species. The other compounds were tentatively characterized by accurate mass measurement and comparing retention times and characteristic MS/MS fragmentation patterns with reference standards. Moreover, fragmentation behaviors of a series of pure standards of starfish polar steroids and polyhydroxysteroid compounds detected in L. fusca have been extensively investigated and characteristic fragmentation pathways were described and used for the characterization of unknown compounds.