Recent Advances in Chain Conformation and Bioactivities of Triple-Helix Polysaccharides

Abstract

Natural polysaccharides derived from renewable biomass sources are regarded as environmentally friendly and sustainable polymers. As the third most abundant biomacromolecule in nature, after proteins and nucleic acids, polysaccharides are also closely related with many different life activities. In particular, β-glucans are one of the most widely reported bioactive polysaccharides and are usually considered as biological response modifiers. Among them, β-glucans with triple-helix conformation have been the hottest and most well-researched polysaccharides at present, especially lentinan and schizophyllan, which are clinically used as cancer therapies in some Asian countries. Thus, creation of these active triple-helix polysaccharides is beneficial to the research and development of sustainable “green” biopolymers in the fields of food and life sciences. Therefore, full fundamental research of triple-helix polysaccharides is essential to discover more applications for polysaccharides. In this Review, the recent research progress of chain conformations, bioactivities, and structure–function relationships of triple-helix β-glucans is summarized. The main contents include the characterization methods of the macromolecular conformation, proof of triple helices, bioactivities, and structure–function relationships. We believe that the governments, enterprises, universities, and institutes dealing with the survival and health of human beings can expect the development of natural bioproducts in the future. Hence, a deep understanding of β-glucans with triple-helix chain conformation is necessary for application of natural medicines and biologics for a sustainable world.

Evaluation of Polish Wild Mushrooms as Beta-Glucan Sources

“…The triple-helix β-glucans with high molecular weight show stronger anticancer properties [ 10 , 15 ]. Mushroom glucans often form intermolecular interactions yielding complex polymers that are difficult to isolate, but recent studies suggest a simple and effective procedure that allows to separate different glucan structures.…”

“…Nitschke et al [ 29 ] found that Congo red binds only Congo red positive β-glucans with the triple-helix structures. However, it should be stressed that the triple helical structures of β-glucans are susceptible for conformation transition in some solvents and under some chemical and physical conditions like very high temperature [ 10 ].…”

“…The main saccharide components of mushroom cell walls are chitin; α-glucans; and β-glucans, mainly 1,3–1,6-β- d -glucans and others like linear 1,3-β- d -glucans and linear and branched 1,6-β- d -glucans [ 1 , 2 , 3 , 4 , 5 ]. Some of these polysaccharides, especially triple-helix 1,3–1,6-β- d -glucans, show a number of proven therapeutic properties, including immunomodulatory, anticancer and antioxidant features [ 6 , 7 , 8 , 9 , 10 ]. Besides glucans, more complex polysaccharides occurring in mushrooms are heteropolysaccharides such as heterogalactans, heteroglucans and heteromannans.…”

“…Among mushroom β-glucans, there are mainly branched glucans, where β- d -glucose molecules are connected by β-1,3 bonds and have short and numerous side chains with β-1,6-link coming off the β-1,3-backbone [ 2 , 8 , 12 , 13 , 14 ]. Mushrooms 1,3–1,6-β- d -glucans in literature are often shortly labeled as β-glucans [ 10 ].…”

“…The beta-glucan molecules of the individual mushroom species differ in the structure of the backbone, the number and type of chemical bonds, as well as the type and number of side chains, structure (e.g., triple helix, single helix or random helix) and molecular weight. According to current knowledge the conformation of the β-glucans is a determining factor of their bioactivity [ 9 , 10 , 21 , 22 , 23 , 24 ].…”