Galactomannan polysaccharides: An updated review on isolation, characterization, bioactivities, and application as...

Galactomannans (GM) are mannose-galactose (Man-Gal) structure-based polysaccharides with different ratios according to the source, isolation, and purification technique. This work provides an update on GM sources, chemistry, isolation and characterization techniques, bioactivities, and their applications as encapsulation agents and drug delivery systems for natural bioactive compounds. The unique chemical structure of GMs gives them a wide range of physical/chemical properties. Current pre-clinical research indicates that GMs exert a plethora of bioactivities (e.g., prebiotic, anti-inflammatory, antioxidant, anti-obesity, antidiabetic, wound healing, cytotoxic, and immunomodulatory activity). Modifications using physical, chemical, and enzymatic procedures generally lead to a further improvement in GMs' physicochemical properties and superior biological effects. These bioactivities depend on GM chemical structure and other properties (Man/Gal ratio, average Mw, degree and type of substitution, branching pattern, surface charge, solubility, viscosity, etc.). Furthermore, GM based-materials (functional hydrogels and films, microcapsules, and microspheres) are used as encapsulating agents and delivery systems of natural bioactive compounds and for metal nanoparticles' synthesis. Besides being biodegradable and biocompatible, GM-based materials have the capacity to improve bioavailability and are capable of controlling the release and enhancing the therapeutic effect of various natural bioactive agents against various diseases, especially dermal pathologies, inflammation, wounds, and bacterial/fungal infections.