Oversulfated chondroitin sulfate is a contaminant in heparin associated with adverse clinical events.

Recently, certain lots of heparin have been associated with an acute, rapid onset of serious side effects indicative of an allergic-type reaction. To identify potential causes for this sudden rise in side effects, we examined lots of heparin that correlated with adverse events using orthogonal high-resolution analytical techniques. Through detailed structural analysis, the contaminant was found to contain a disaccharide repeat unit of glucuronic acid linked beta1-->3 to a beta-N-acetylgalactosamine. The disaccharide unit has an unusual sulfation pattern and is sulfated at the 2-O and 3-O positions of the glucuronic acid as well as at the 4-O and 6-O positions of the galactosamine. Given the nature of this contaminant, traditional screening tests cannot differentiate between affected and unaffected lots. Our analysis suggests effective screening methods that can be used to determine whether or not heparin lots contain the contaminant reported here.

Structure of a heteroxylan of gum exudate of the palm Scheelea phalerata (uricuri).

The polysaccharide isolated from the gum exudate of palm Scheelea phalerata (SPN) was water-insoluble and composed of Fuc, Ara, Xyl, and uronic acid moieties in a 5:34:54:7 molar ratio: 12% of phenolics were also present. A soluble polysaccharide (SPNa) was obtained after alkaline treatment, which contained Fuc, Ara, Xyl and uronic acid in a 7:44:42:7 molar ratio, with only 2% phenolics. SPNa had an M(W) approximately 1.04 x 10(5) g mol(-1) and was almost monodisperse (M(W)/M(N) : 1.25 +/-0.22). It had a branched structure with side chains of 2-O-substituted Xylp (approximately 8%) and 3-O-substituted Araf (12%) units, and a large proportion of nonreducing end-units of Araf (15%), Fucp (10%), Xylp (4%), and Arap (6%). The (1 --> 4)-linked beta-Xylp main-chain units were 3-O- (9%), 2-O- (13%), and 2,3-di-O- (13%) substituted. Its (13)C NMR spectrum contained at least 9 C-1 signals, those at delta 108.6 and 107.7 arising from alpha-Araf units. Others were present at delta 175.4 from C-6 of alpha-GlcpA and delta 15.6 from C-6 of Fucp units. The main chain of SPNa was confirmed by analysis of a Smith-degraded polysaccharide (SPDS): methylation analysis provided a 2,3-Me(2)-Xyl (65%) derivative and its (13)C NMR spectrum showed five main signals typical of a (1 --> 4)-linked beta-Xylp units. Methylation analysis of a carboxy-reduced polysaccharide (SPN-CR) revealed a 2,3,4,6-Me(4)-Glc derivative (4%) arising from nonreducing end-units of GlcpA. Alpha-GlcpA-(1 --> 2)-alphabeta-Xy1p and alpha-GlcpA-(1 --> 2)-beta-Xylp-(1 --> 4)-alphabeta-Xylp were obtained via partial acid hydrolysis of SPN, showing the structure of side-chain substituents on O-2 of the main-chain units.

Inhibition of B16-BL6 melanoma lung colonies by semisynthetic sulfaminoheparosan sulfates from E. coli K5 polysaccharide.

Heparin (H), heparan sulfate (HS), and related glycosaminoglycans can inhibit cancer cell invasion, possibly due to their ability to interact with vascular growth factors, adhesion molecules, endoglycosidases, and signaling proteins, in addition to the well-known effects on the clotting system. We evaluated the antitumor activity of a series of semisynthetic sulfaminoheparosan sulfates (SAHSs) with different degree and distribution of sulfates, obtained by chemical modifications of the E. coli K5 polysaccharide, namely type A, B, and C compounds. B16-BL6 melanoma cells (10 5 cells/mouse) were injected intravenously (i.v.) in a lateral tail vein of C57BL6 mice at a dose of 0.5 mg/ mouse together with test compounds. Tumor lung nodules were significantly reduced as compared with controls only by H (95.5 +/- 1.0% inhibition), SAHS-2 (84.2 +/- 5.0% inhibition), and SAHS-4 (91.1 +/- 4.2% inhibition), among compounds tested. SAHS-2 and SAHS-4 are type B compounds, with a sulfate/carboxylate ratio similar to that of H. A typical mammalian HS showed only 54.8% inhibition. Supersulfated low-molecular-weight heparin and heparan sulfate (ssLMWH and ssLMWHS) showed an activity similar to that of unfractionated compounds. H and SAHS-4 inhibited dose dependently B16-BL6 lung colonies, with IC-50 values of 0.05 and 0.1 mg/mouse, respectively. The relationship with ex vivo anticoagulant potency was evaluated by activated partial thromboplastin time (aPTT) on mouse plasma at different time intervals after i.v. injection (0.1 to 0.5 mg/mouse) of the compound. H showed a dose-dependent anticoagulant activity lasting up to 2 hours, whereas SAHS-4 showed a potent anticoagulant effect only at a dose of 0.5 mg/mouse. Accordingly, H but not SAHS-4 consistently inhibited B16-BL6 lung colonies when given 1 hour before tumor cells. SAHS-4 derivatives, with different size and/or affinity depleted of AT binding sites, showed an inhibitory effect on B16-BL6 melanoma similar to that of SAHS-4, suggesting that the greater antitumor effect of H was not due to AT-mediated inhibition of blood clotting. Interactions with other blood inhibitors, such as heparin cofactor II or tissue factor pathway inhibitory protein cannot be ruled out. The better effect of H may be due to persistence in the circulation and/or ability to inhibit tumor neoangiogenesis.