Characterization of meFucoidan as a selective inhibitor for secretory phospholipase A2-IIA and the phosphorylation of meFucoidan-binding proteins by A-kinase in vitro

Recent research advances in polysaccharides from Undaria pinnatifida: Isolation, structures, bioactivities, and applications

Undaria pinnatifida, one of the most widespread seafood consumed in China and many other nations, has been traditionally utilized as an effective therapeutically active substance for edema, phlegm elimination and diuresis, and detumescence for more than 2000 years. Numerous studies have found that polysaccharides of U. pinnatifida play an indispensable role in the nutritional and medicinal value. The water extraction and alcohol precipitation method are the most used method. More than 40 U. pinnatifida polysaccharides (UPPs) were successfully isolated and purified from U. pinnatifida, whereas only few of them were well characterized. Pharmacological studies have shown that UPPs have high-order structural features and multiple biological activities, including anti-tumor, antidiabetic, immunomodulatory, antiviral, anti-inflammatory, antioxidant, anticoagulating, antithrombosis, antihypertension, antibacterial, and renoprotection. In addition, the structural characteristics of UPPs are closely related to their biological activity. In this review, the extraction and purification methods, structural characteristics, biological activities, clinical settings, toxicities, structure-activity relationships and industrial application of UPPs are comprehensively summarized. The structural characteristics and biological activities as well as the underlying molecular mechanisms of UPPs were also outlined. Furthermore, the clinical settings and structure-activity functions of UPPs were highlighted. Some research perspectives and challenges in the study of UPPs were also proposed.

Mekabu fucoidan: structural complexity and defensive effects against avian influenza A viruses

Fucoidan from the sporophyll (Mekabu) of brown seaweed Undaria pinnatifida (wakame) is interesting due to its various biological activities. Mekabu fucoidan (Mw ∼ 9 kDa) of this study (MF) was previously isolated and characterized by chemical and separation methods including GPC and methylation analysis (Lee, Hayashi, Hashimoto, Nakano, & Hayashi, 2004). It was found that this fucoidan composed of partially sulphated (DS ∼ 0.72) fucose and galactose at approximately equal amounts. Methylation analyses revealed complex structure of MF. However, it has been still unclear about the linkages between units and substitution patterns. To solve these structural tasks, spectroscopic methods (FTIR, FT Raman and NMR) were used in the analysis of native MF and its deesterified derivatives. According to obtained results, this polysaccharide was defined as O-acetylated sulphated fucogalactan. The defensive effects of MF were evaluated on mice infected with avian influenza A viruses (H5N3 and H7N2 subtypes); its efficacy was determined in reducing viral replication and increasing antibody production. Oral administration of MF resulted in suppressing virus yields. In addition, the production of neutralizing antibodies and mucosal IgA in the animals inoculated with the avian influenza A viruses was significantly increased. These results suggested that MF could be used for the prevention of viral infection.

Biochemical characterization of epigallocatechin-3-gallate as an effective stimulator for the phosphorylation of its binding proteins by glycogen synthase kinase-3β in vitro

The stimulatory and inhibitory effects of epigallocatechin-3-gallate (EGCG) and its related two compounds (luteolin and quercetin) on the phosphorylation of four proteins [bovine myelin basic protein (bMBP), human recombinant tau protein (hrTP), human recombinant vimentin (hrVM) and rat collapsin response mediator protein-2 (rCRMP-2)] by glycogen synthase kinase-3β (GSK-3β) were comparatively determined in vitro. We found that (i) EGCG, not quercetin and luteolin, highly stimulated the GSK-3β-mediated phosphorylation of hrTP and significantly stimulated the phosphorylation of bMBP and hrVM by the kinase; (ii) these three polyphenols inhibited dose-dependently the phosphorylation of rCRMP-2 by GSK-3β; (iii) only EGCG significantly enhanced autophosphorylation of GSK-3β; and (iv) EGCG had a binding-affinity with two basic proteins (bMBP and hrTP) and a low affinity with rCRMP-2 rather than hrVM in vitro. In addition, the binding of EGCG to these two basic proteins induced to highly stimulate their phosphorylation, including novel potent sites for GSK-3β, and to significantly reduce the K(m) value and increase the V(max) value of these two substrate proteins for the kinase in vitro. These results provided here suggest that EGCG acts as an effective stimulator for the GSK-3β-mediated phosphorylation of its binding proteins containing EGCG-inducible phosphorylation sites for the kinase in vitro.