Physiochemical changes, metabolite discrepancies of brown seaweed-derived sulphated polysaccharides in the upper gastrointestinal tract and their effects on bioactive expression

• Published in: International journal of biological macromolecules 2024-06, Vol.272 (Pt 1), p.132845, Article 132845
• Main Authors: Xie, Cundong, Leeming, Michael G., Lee, Zu Jia, Yao, Shenggen, van de Meene, Allison, Suleria, Hafiz A.R.
• Format: Article
• Language: English
• Subjects: Bioactivities; Brown seaweeds; Fucoidan; Laminarin; Simulated digestion; Sulphated polysaccharides
• ISSN: 0141-8130; 1879-0003; 1879-0003
• DOI: 10.1016/j.ijbiomac.2024.132845

Brown seaweed-derived polysaccharides, notably fucoidan and laminarin, are known for their extensive array of bioactivities and physicochemical properties. However, the effects of upper digestive tract modification on the bioactive performance of fucoidan and laminarin fractions (FLFs) sourced from Australian native species are largely unknown. Here, the digestibility and bioaccessibility of FLFs were evaluated by tracking the dynamic changes in reducing sugar content (CR), profiling the free monosaccharide composition using LC-MS, and comparing high-performance gel permeation chromatography profile variation via LC-SEC-RI. The effects of digestive progression on bioactive performance were assessed by comparing the antioxidant and antidiabetic potential of FLFs and FLF digesta. We observed that molecular weight (Mw) decreased during gastric digestion indicating that FLF aggregates were disrupted in the stomach. During intestinal digestion, Mw gradually decreased and CR increased indicating cleavage of glycosidic bonds releasing free sugars. Although the antioxidant and antidiabetic capacities were not eliminated by the digestion progression, the bioactive performance of FLFs under a digestive environment was reduced contrasting with the same concentration level of the undigested FLFs. These data provide comprehensive information on the digestibility and bioaccessibility of FLFs, and shed light on the effects of digestive progression on bioactive expression. [Display omitted] •There was a decrease in Mw of FLFs during the gastric and intestinal digestion phases.•FLFs possessed free radicals scavenging abilities with dose-dependent features.•FLFs showed more effective α-glucosidase inhibitory activities than α-amylase.•The bioactivities of FLFs were not eliminated by gastrointestinal digestion.