Plant endophytic fungal polysaccharides and their activities: A review

Endophytic fungi, essential constituents of plant microecosystems, have attracted considerable scientific interest due to their remarkable biodiversity, ecological adaptability, and capacity to synthesize a wide range of bioactive metabolites. Among these, polysaccharides produced by endophytic fungi represent a promising yet insufficiently investigated class of macromolecules with significant pharmacological and biotechnological applications. However, research on these polysaccharides remains constrained by limited exploration. This review systematically consolidates current advances in the classification, extraction, purification, structural elucidation, and biological functions of endophytic fungal polysaccharides (EFPs), while also examining their interactions with host plants. The potential of polysaccharide-producing endophytic fungi remains largely underexplored. Furthermore, inherent polysaccharide complexity, combined with technical limitations, has confined most studies to extracellular polysaccharides, leaving comprehensive structural analyses scarce. EFPs demonstrate antioxidant, antibacterial, immunomodulatory, and antitumor activities, and contribute substantially to the symbiotic dynamics between fungi and host plants, yet systematic activity profiling is insufficient. This review proposes establishing a targeted resource development framework to enhance the diversity of polysaccharide compounds and advocates for the integration of conventional and advanced methodologies to advance pharmacological investigations and functional analyses of EFPs, thereby offering strategic insights for future applications and facilitating deeper exploration and utilization.