| Summary: | Crude anionic polysaccharides extracted from the Pacific starfish <i>Lethasterias fusca</i> were purified by anion-exchange chromatography. The main fraction <b>LF,</b> having MW 14.5 kDa and dispersity 1.28 (data of gel-permeation chromatography), was solvolytically desulfated and giving rise to preparation <b>LF-deS</b> with a structure of dermatan core [→3)-β-<span style="font-variant: small-caps;">d</span>-GalNAc-(1→4)-α-<span style="font-variant: small-caps;">l</span>-IdoA-(1→]<sub>n</sub>, which was identified according to NMR spectroscopy data. Analysis of the NMR spectra of the parent fraction <b>LF</b> led to identification of the main component as dermatan sulfate <b>LF-Derm</b> →3)-β-<span style="font-variant: small-caps;">d</span>-GalNAc4R-(1→4)-α-<span style="font-variant: small-caps;">l</span>-IdoA2R3S-(1→ (where R was SO<sub>3</sub> or H), bearing sulfate groups at O-3 or both at O-2 and O-3 of α-<span style="font-variant: small-caps;">l</span>-iduronic acid, as well as at O-4 of some N-acetyl-<span style="font-variant: small-caps;">d</span>-galactosamine residues. The minor signals in NMR spectra of <b>LF</b> were assigned as resonances of heparinoid <b>LF-Hep</b> composed of the fragments →4)-α-<span style="font-variant: small-caps;">d</span>-GlcNS3S6S-(1→4)-α-<span style="font-variant: small-caps;">l</span>-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 <b>LF-Derm</b> and <b>LF-Hep</b>, a series of variously sulfated model 3-aminopropyl iduronosides were synthesized and their NMR spectra were compared with those of the polysaccharides. Preparations <b>LF</b> and <b>LF-deS</b> 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.
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