earticle

영어

Owing to our recent understanding of the fundamental glycobiology describing crucial roles of glycan chains attached to gycoconjugates in many important physiological and pathogenic processes, such as cell surface recognition, signal transduction, tumor metastasis, etc., and significant advances in carbohydrate analysis, synthesis, and medical applications over the past decades, carbohydrate-based therapeutic drugs are suddenly on attracting menu in the biomedical field. Polysaccharides are widely distributed in nature and show diversity in their structures, physico-chemical properties, and various interesting bioactivities, offering a variety of potential applications in the fields of foods, cosmetics, drug-delivery, tissue engineering and regenerative medicine, vaccines, and pharmaceutical industries. For example, the capsular polysaccharide of Haemophilus influenzae type b (Hib), a major causative of bacterial meningitis, was successfully developed as a Hib vaccine. The anticoagulant heparin and anti-diabetic drug acarbose have long been the number-one-selling drugs in the world. Sulfated polysaccharides (SPSs) having sulfate esters on their sugar residues and their lower molecular weight oligosaccharide derivatives from marine seaweeds such as brown, red, and green algae, have been shown to possess a variety of biological and pharmacological activities, including anticancer, immunostimulatory, anti-inflammatory, anti-coagulant, antioxidant, antibacterial, and antiviral activities. It is now generally recognized that biological and pharmacological activities, including antiviral activity, of SPSs depend on a complex interplay of structural features including the degree of sulfation (charge density), distribution of sulfate groups on their sugar residues, molecular weight, monosaccharide composition, and stereochemistry. We have isolated and purified polysaccharides, a sulfated galactofucan (tentatively named MF) from the sporophill of Korean brown alga Undaria pinnatifida and a sulfated glucuronorhamnoxylan (named SPS-CF) from a green alga Capsosiphon fulvescens, and determined their chemical structures. We also prepared lower-sized polysaccharides (LMMGFs, 1 ~ 4 kDa) from the high-molecular weight MF (~ 2,000 kDa) by enzymatic digestion. This talk focuses on the antiviral and anticancer activities of these polysaccharides and discuss the effects of their molecular weight and degree of sulfation on these bioactivities. On the other hand, flavonoids and anthraquinones are the most abundant natural polyphenolic comounds in plants and have diverse health beneficial effects including anti-cancer, anti-inflammatory, antioxidant, anti-obesity, anti-diabetic, anti-osteoporotic, and immunostimulatory activities. Interestingly, these phenolic compounds observed in nature almost all exist in glycosylated forms in plants, with sugar groups such as glucose, galactose, rhamnose, arabinose, xylose, and rutinose. Glycosylation of phenolic compounds has been reported to increase water-solubility and bioavailability, reduce toxicity, and sometimes give improved or novel pharmacological activities. We have evaluated and compared the bioactivities of various non-glycosylated (aglycone) and glycosylated phenolic compounds against several disease models in vitro and in vivo. This talk also discuss the beneficial effects of glycosylation of phenolic compounds especially on their immunostimulating and anti-obesity activities.