A combination of polysaccharides and tea polyphenols can enhance immune activity synergistically, depending on the type and structure of polysaccharides, but the mechanism remains unknown. This study is aimed to investigate the regulating effects of different seaweed polysaccharide (ι-carrageenan, agarose) and tea polyphenol blends on intestinal flora and intestinal inflammation using an in vitro ascending–transverse–descending colon fermentation system and RAW264.7 cell model. The results showed that seaweed polysaccharides in the presence of tea polyphenol were almost completely degraded at transverse colon fermentation for 36 h. Agarose significantly enhanced the butyric acid production content by increasing the abundance of Lachnospiraceae, whereas agarose and tea polyphenol blends did not have a synergistic effect. On the contrary, ι-carrageenan and tea polyphenol blends synergistically increased the abundance of beneficial bacteria (e.g., Bacteroidetes and Bifidobacterium) and promoted the production of short-chain fatty acids (SCFAs), such as isobutyric acid. Such changes tended to alter the impacts of different seaweed polysaccharides and tea polyphenol blends on intestinal inflammation. Among them, ι-carrageenan and tea polyphenol blends were the most effective in inhibiting lipopolysaccharide-induced NO, ROS, IL-6, and TNF-α production in RAW264.7 cells, indicating the alleviated intestinal inflammation. The results suggest that the seaweed polysaccharide and tea polyphenol blends have prebiotic potential and can benefit intestinal health.

Pomelo fruitlets have the potential for extracting cellulose. This study aimed to investigate characterization and functionality of cellulose extracted from pomelo fruitlets by different extraction methods. Cellulose extracted by acidic-alkaline hydrogen peroxide hydrolysis (CAA), alkaline hydrogen peroxide hydrolysis (CA), and ultrasonic assisted alkaline hydrogen peroxide hydrolysis (CUA) were prepared from pomelo fruitlets. The results showed that cellulose CUA had higher yield and purity with higher crystallinity and smaller particle size than those of CAA or CA (p < 0.05). Specifically, the yield of CUA was 82.75% higher than that of CAA, and purity was increased by 26.42%. Additionally, water- and oil-holding capacities of CUA were superior to those of CAA or CA, increasing by 13–23% and 10–18%, respectively. The improvement of water- and oil-holding capacities were highly related to its smaller particle size with increased surface area. The results suggested that ultrasonic assisted alkaline hydrogen peroxide hydrolysis is a promising and efficient method to prepare high-purity cellulose from pomelo fruitlets, and this cellulose is expected to be a food stabilizer and pharmaceutical additive.

To find natural and safe anti-diabetic foods or potential drugs, low-molecular-weight saccharide fragments LMWAs-H (M_w 33.48 kDa) and LMWAs-L (M_w 6.71 kDa) from the sulfated polysaccharide ascophyllan of Ascophyllum nodosum using alginate lyase (EC 4.2.2.3) were investigated. The results revealed that LMWAs-H possessed potent inhibition activity against α-glucosidase or α-amylase in a concentration-dependent manner, which were higher than native ascophyllan or LMWAs-L. LMWAs-H exhibited a stronger inhibitory activity against α-glucosidase than α-amylase because it differently affects the conformational structures of these enzymes. Structural analysis revealed LMWAs-H to be →4)-α-L-Fucp-(1 → 4)-α-L-Fucp-(1 → 3)-β-D-Xylp-(1 → 3)-α-L-Fucp4S(1→ as main chain, and T-α-D-Glcp-(1→ and →3)-β-D-ManpA_red residues were attached to the ends of main chain as non-reducing- and reducing-end residues, respectively. The 4-deoxy-L-erythro-hex-4-enuronosyluronate linked the O-4 position of →3,4)-β-D-ManpA_red residue as side branches. Our results suggest that LMWAs-H is the main active structural motif responsible for the enzymes-inhibiting activities, which is probably derived from the fucose-containing branches of ascophyllan. Our findings reveal that the strong inhibition of LMWAs-H on α-glucosidase but mild inhibition on α-amylase is highly related to its structural properties, suggesting its desirable characteristics as an anti-diabetic agent.