- Xyloglucan is a plant-derived polysaccharide that belongs to the hemicellulose family and is one of the major components of primary cell walls in most higher plants.
- Structurally, it consists of a linear backbone of β-(1→4)-linked glucose residues, similar to cellulose, but with frequent substitutions of side chains containing xylose, galactose, fucose, or arabinose. These substitutions give xyloglucan a highly branched architecture and influence its solubility, binding properties, and interactions with other wall components. The exact branching pattern varies across plant species, contributing to differences in xyloglucan’s biological and functional properties.
- In the plant cell wall, xyloglucan plays a critical structural role by tethering cellulose microfibrils together. This cross-linking forms a flexible yet strong network that provides mechanical strength while allowing controlled wall loosening during growth. Xyloglucan–cellulose interactions are dynamic, regulated by specific enzymes such as xyloglucan endotransglycosylase/hydrolases (XTHs), which cut and rejoin xyloglucan chains. This enzymatic remodeling contributes to cell expansion, tissue development, and plant morphogenesis. By serving as both a structural stabilizer and a flexible matrix component, xyloglucan is indispensable for maintaining the balance between rigidity and plasticity in the primary wall.
- From a biological perspective, xyloglucan also influences plant–microbe interactions and environmental responses. Modifications in xyloglucan structure or metabolism can affect plant resistance to pathogens, cell adhesion, and water relations. Additionally, during seed germination, xyloglucan is mobilized as an energy source, particularly in legumes, where it accumulates in seed cell walls as a reserve carbohydrate. This dual role—as both a structural and storage polysaccharide—underscores its versatility in plant physiology.
- In human nutrition, xyloglucan functions as a soluble dietary fiber. Humans cannot enzymatically digest it in the small intestine, but it is fermented in the colon by gut microbiota, producing short-chain fatty acids (SCFAs) that support intestinal health and systemic metabolic functions. Certain xyloglucan-derived oligosaccharides act as prebiotics, selectively stimulating beneficial bacterial populations. Xyloglucan’s ability to increase stool bulk and regulate intestinal transit has led to its use in dietary supplements and functional foods aimed at improving digestive health.
- Beyond nutrition, xyloglucan has important pharmaceutical and industrial applications. It has been formulated as a bioadhesive and mucoadhesive agent for controlled drug delivery, particularly in oral and nasal systems. Its biocompatibility, non-toxicity, and gel-forming ability also make it suitable for wound dressings and tissue engineering scaffolds. In the food industry, xyloglucan is valued as a thickener and stabilizer, while in cosmetics it is explored for moisturizing and film-forming properties. Biotechnological advances in enzymatic modification are further expanding its potential, enabling tailored xyloglucan derivatives with novel functionalities.
