- Arabinose is a naturally occurring pentose sugar (five-carbon monosaccharide) with the molecular formula C₅H₁₀O₅. It belongs to the class of aldopentoses, characterized by an aldehyde functional group at the first carbon. Arabinose exists in two stereoisomeric forms, L-arabinose and D-arabinose, with the L-isomer being the predominant form found in nature. Unlike glucose and other hexoses, arabinose is less common as a free sugar but is widely distributed as a component of plant polysaccharides.
- In plants, arabinose frequently occurs as a side-chain sugar in hemicelluloses, pectins, and glycoproteins. One of its most significant roles is in arabinans and arabinoxylans, where it contributes to the complexity and branching of polysaccharide structures. Arabinose residues are also present in arabinogalactans, which are important structural and signaling molecules in plant cell walls and gums. These arabinose-containing polymers provide flexibility, hydration, and interactions within the cell wall matrix, thereby influencing plant growth and resilience.
- Biologically, arabinose has functional importance in both plants and microbes. In bacteria, it is central to the regulation of gene expression through the arabinose operon (ara operon), which is widely used in molecular biology as a model system and as a tool for inducible gene expression in recombinant DNA technology. In humans and other animals, arabinose is not a major dietary sugar, but it can be metabolized to some extent via the pentose phosphate pathway after conversion into intermediate sugars. Additionally, certain studies suggest that L-arabinose inhibits sucrase activity in the small intestine, reducing the digestion of sucrose and thereby lowering postprandial blood glucose, which has implications for managing diabetes and obesity.
- From an industrial perspective, arabinose and its derivatives have growing significance. It can be used as a starting material for the synthesis of fine chemicals, pharmaceuticals, and bio-based products. Arabinose-containing polysaccharides, such as arabinogalactans, are exploited for their immunomodulatory, prebiotic, and antioxidant properties, making them valuable in nutraceuticals and functional foods. Furthermore, arabinose is being investigated as a renewable resource from agricultural by-products for the production of biofuels and bioplastics.
