A systematic review on polysaccharides from fermented Cordyceps sinensis: Advances in the preparation, structural characterization, bioactivities, structure-activity relationships

Cordyceps sinensis (Berk.) Sacc. (Ophiocordyceps sinensis) is an edible and medicinal fungus used as a natural superior tonic. It is considered as scarce fungus with a high market demand. Therefore, as an alternative, fermentation technology has been proposed to produce artificial cordyceps (fermented C. sinensis) to address the shortage of cordyceps resources for industrialization and commercial utilization. Numerous studies have proved that polysaccharides are the important bioactive substances in the fermented C. sinensis, but the research data lack systematic review. In this review, current relevant research data regarding the preparation (including extraction, fractionation, and purification), structural characterization (including molecular weight, monosaccharide composition, glycosidic bond type, structural and conformational features), bioactivities, structure-activity relationships (SAR) and applications of polysaccharides from different sources of fermented C. sinensis last decade were analyzed and discussed. The findings highlight that the most commonly employed methods for preparing fermented Cordyceps sinensis polysaccharides (FCSPs) involve water extraction and alcohol precipitation, combing with sophisticated chromatographic techniques such as ion exchange and gel permeation chromatography. From these processes, 34 different polysaccharides were identified including 5 glucans and 7 heteropolysaccharides that were thoroughly characterized. FCSPs exhibited a broad spectrum of biological activities, ranging from antioxidant and renal protective effects to immunomodulatory, antitumor, and hypolipidemic properties. The structure-activity relationships (SAR) demonstrated that key factors, such as molecular weight, monosaccharide composition and glucosidic bond types, play critical roles in determining the bioactivity of FCSPs. Nevertheless, there remain unknown elements that continue to influence SAR, leaving room for further exploration. Furthermore, the limitation of existing studies and some new perspectives for future investigations on FCSPs were proposed.