Polysaccharides from edible macroalgae: their extraction, purification, and therapeutic potentials in inflammation and oxidative stress-related diseases

Chronic inflammation and oxidative stress are two interconnected biological processes, which have critical roles in onset or pathogenesis of diverse health disorders, such as rheumatoid arthritis, inflammatory bowel disease, obesity, diabetes, and neurodegenerative diseases. This review study aims to consolidate the current literature knowledge on extraction and purification methods of macroalgal polysaccharides, as well as their therapeutic roles in diseases associated with chronic inflammation and oxidative stress. The in vivo animal studies and human clinical trials reveal that macroalgal polysaccharides, especially edible ones, can reduce symptoms of these diseases through antioxidant and anti-inflammatory actions. The underlying mechanisms of their antioxidant and anti-inflammatory properties include the reduction of reactive oxygen species production, lipid peroxidation and nitric oxide synthesis, the down-regulation of pro-inflammatory cytokines and inflammatory enzymes, along with the concomitant increase of anti-inflammatory cytokines, anti-inflammatory transcription factors, and antioxidant enzymes. In addition, they also indirectly reduce symptoms of chronic inflammation and oxidative stress-related diseases by supporting the growth of beneficial gut bacteria that produce natural metabolites with anti-inflammatory and antioxidant activities. In conclusion, the available evidence indicates that macroalgal polysaccharides may be used as ingredients in food, cosmetic, and pharmaceutical formulations to combat diseases associated with oxidative stress and chronic inflammation.