Zinc-polysaccharide complexes: Advances in preparation, characterization, bioactivities, and application

Zinc-polysaccharide complexes are novel functional complexes formed through the chelation of Zn²⁺ with active groups (such as hydroxyl and carboxyl groups) on polysaccharide chains. This process not only alters the host structure and physicochemical properties of the polysaccharides but also synergistically enhances the bioactivity of both Zn²⁺ and the polysaccharides themselves, exhibiting multiple physiological functions including antioxidant, hypoglycemic, antitumor, and immunomodulatory effects. Due to their natural origin, high bioavailability, and excellent safety profile, zinc-polysaccharide complexes represent a promising new class of zinc supplements. Furthermore, they demonstrate significant potential in pharmaceutical applications and as agricultural feed additives. This paper systematically summarizes and compares the preparation methods of zinc-polysaccharide complexes, including plant transformation, fermentation, and chemically synthesized approaches, and analyzes their structural characteristics, biological activities, and application potential. At the same time, this paper highlights the challenges in current research, such as technical bottlenecks in large-scale production associated with different preparation methods, including the poor product uniformity and uncontrollable molecular weight associated with chemical synthesis, the susceptibility of fermentation methods to zinc toxicity, and the excessively long production cycle of plant-based conversion methods; insufficient structure-activity relationship (SAR) studies, most of which remain at the level of phenomenological descriptions; the lack of standardized clinical studies on in vivo pharmacokinetic profiles, long-term safety evaluations, and standardized quality control, and discusses future directions. This review aims to comprehensively summarize recent research progress on zinc-polysaccharide complexes, provide a theoretical reference for subsequent studies, and promote the continued development and practical application of these complexes.