Microwave-assisted extraction (MAE) is an emerging technology to obtain polysaccharides with an extensive
spectrum of biological characteristics. In this study, the hypoglycemic, hypolipidemic, prebiotic, and immunomodulatory (e.g., antiinflammatory, anticoagulant, and phagocytic) effects of algal- and plant-derived polysaccharides rich in glucose, galactose, and mannose using MAE were comprehensively discussed. The in vitro and
in vivo results showed that these bioactive macromolecules with the low digestibility rate could effectively
alleviate the fatty acid-induced lipotoxicity, acute hemolysis, and dyslipidemia status. The optimally extracted
glucomannan- and glucogalactan-containing polysaccharides revealed significant antidiabetic effects through
inhibiting α-amylase and α-glucosidase, improving dynamic insulin sensitivity and secretion, and promoting
pancreatic β-cell proliferation. These bioactive macromolecules as prebiotics not only improve the digestibility in
gastrointestinal tract but also reduce the survival rate of pathogens and tumor cells by activating macrophages
and producing pro-inflammatory biomarkers and cytokines. They can effectively prevent gastrointestinal disorders and microbial infections without any toxicity