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The structural characterization and the anticoagulant potential of a novel heparin/heparan sulfate-like compound from the heads of Litopenaeus vannamei shrimp are described. While it is distinct from either heparin or heparan sulfate, enzymatic depolymerization and nuclear magnetic resonance spectroscopy analyses revealed that this molecule does share some structural features with heparin, such as the high degree of N- and 6-O-sulfation and minor N-acetylation, and with heparan sulfate, in the glucuronic acid content. Its ability to stabilize human antithrombin explains its significant anticoagulant activity in aPTT and Factor-Xa inhibition assays. Interestingly, in contrast to mammalian heparin, the shrimp compound displayed negligible hemorrhagic effect. Together, these findings have particular interest since they reveal a novel molecule with significant anti-Xa activity coupled with low bleeding effects which make the shrimp heparin/HS-like compound a potential alternative for mammalian heparin.

Summary. Background: Choroidal neovascularization (CNV) is the main cause of severe visual loss in age-related macular degeneration (AMD). Heparin/heparan sulfate are known to play important roles in neovascularization due to their abilities to bind and modulate angiogenic growth factors and cytokines. Previously, we have isolated from marine shrimp a heparin-like compound with striking anti-inflammatory action and negligible anticoagulant and hemorrhagic activities. Objectives: To investigate the role of this novel heparin-like compound in angiogenic processes. Methods and Results: The anti-angiogenic effect of this heparinoid in laser-induced CNV and in vitro models is reported. The compound binds to growth factors (FGF-2, EGF and VEGF), blocks endothelial cell proliferation and shows no cytotoxic effect. The decrease in proliferation is not related to cell death either by apoptosis or secondary necrosis. The results also showed that the heparinoid modified the 2-D network organization in capillary-like structures of endothelial cells in Matrigel and reduced the CNV area. The effect on CNV area correlates with decreases in the levels of VEGF and TGF-b1 in the choroidal tissue. The low content of 2-O-sulfate groups in this heparinoid may explain its potent anti-angiogenic effect. Conclusions: The properties of the shrimp heparinoid, such as potent antiangiogenic and anti-inflammatory activities but insignificant anticoagulant or hemorrhagic actions, point to this compound as a compelling drug candidate for treating neovascular AMD and other angioproliferative diseases. A mechanism for the anti-angiogenic effect of the heparinoid is proposed.

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The occurrence of a natural and unmodified highly sulfated chondroitin sulfate from Litopenaeus vannamei heads (sCS) is herein reported. Its partial digestion by Chondroitinases AC and ABC together with its electrophoretic migration profile revealed it as a highly sulfated chondroitin sulfate despite its average molecular weight being similar to CSA. Using orthogonal 1D/2D NMR experiments, the anomeric signals (δ 4.62/106.0) corresponding to unusual 2,3-di-O-Sulfo-GlcA (∼36%), U3 (δ 4.42/84.1, ∼63%) and U2 (4.12/80.1, ∼50%) substitutions were confirmed. In addition, non-sulfated GlcA (δ 4.5/106.3) linked to 4-O- (A1, 36%) or 6-O-Sulfo (A1, 28%) GalNAc (δ 4.64/103.5) was observed. Although the biological role of sCS in shrimp is unknown, its influence on hemostasis was also demonstrated. The sCS identification brings to light new questions about the hierarchical model of GAGs biosynthesis and contributes to the better understanding of the subtle relationship between GAGs structure and function.

The detailed structure of a further Chondroitin Sulfate from Litopenaeus vannamei shrimp (sCS) is described. The backbone structure was established by 1 H/ 13 C NMR, which identified 3-O-sulfated GlcA, 4-O-sulfated GalNAc, 6-O-sulfated GalNAc, and 4,6-di-O-sulfated GalNAc residues. GlcA is linked to GalNAc 4,6 di S and GlcA 3S is linked to GalNAc 4S, GalNAc 4,6 di-S and GalNAc6S residues. The anticoagulant properties of this sCS were evaluated by activated partial thromboplastin time, anti-IIa, anti-Xa and anti-heparin cofactor II-mediated activities, and sCS failed to stabilise antithrombin in a fluoresence shift assay. The anti-inflammatory effect of sCS was explored using a model of acute peritonitis, followed by leukocyte count and measurement of the cytokines, IL-1β, IL-6 and TNF-α. The compound showed low clotting effects, but high anti-IIa activity and HCII-mediated thrombin inhibition. Its anti-inflammatory effect was shown by leukocyte recruitment inhibition and a decrease in pro-inflammatory cytokine levels. Although the biological role of sCS remains unknown, its properties indicate that it is suitable for studies of multi-potent molecules obtained from natural sources.

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