The use of green marine seaweed Ulva spp. as foods, feed supplements, and functional ingredients has gained increasing interest. Microwave-assisted extraction technology was employed to improve the extraction yield and composition of Ulva pertusa polysaccharides. The antioxidant activity of ulvan was also evaluated. The impacts of four independent variables, i.e., extraction time (X₁, 30 to 60 min), power (X₂, 500 to 700 W), water-to-raw-material ratio (X₃, 40 to 70), and pH (X₄, 5 to 7) were evaluated. The chemical structure of different polysaccharides fractions was investigated via FT-IR and the determination of their antioxidant activities. A response surface methodology based on a Box–Behnken design (BBD) was used to optimize the extraction conditions as follows: extraction time of 43.63 min, power level of 600 W, water-to-raw-material ratio of 55.45, pH of 6.57, and maximum yield of 41.91%, with a desired value of 0.381. Ulvan exerted a strong antioxidant effect against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and showed reducing power in vitro. Ulvan protected RAW 264.7 cells against H₂O₂-induced oxidative stress by upregulating the expression and enhancing the activity of oxidative enzymes such as superoxide dismutase (SOD) and superoxide dismutase (CAT). The results suggest that the polysaccharides from U. pertusa might be promising bioactive compounds for commercial use.

In the present study, we assessed the extraction of low molecular weight soluble polysaccharides (MESP) from soybean by-products using microwave-assisted enzymatic technology and proposed the chemical structure of MESP using Fourier transform-infrared spectroscopy, gas chromatography, and ¹H and ¹³C nuclear magnetic resonance spectrum analysis. The results suggested that MESP mainly comprised arabinose, rhamnose, and glucuronic acid with (1→4) glycosidic linkages in the backbone. Compared with inulin, MESP was found to selectively stimulate the growth of Lactobacillus probiotics. Moreover, the results of in vitro fermentation indicated that MESP significantly increased the concentrations of both acetate and butyrate (p < 0.05). MESP were treated on lipopolysaccharide (LPS)-stimulated RAW264.7 cells to determine the anti-inflammatory effect in vitro. It was observed that MESP inhibited nitric oxide, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and IL-10 production. Furthermore, Western blotting results indicated that MESP significantly attenuated LPS-induced downregulation of phosphorylation levels of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) in macrophages. The underlying mechanism might involve inhibition of the expression of pro-inflammatory cytokines, presumably via JAK2/STAT3 pathway. Collectively, the results of our study paved way for the production of MESP, which may be potentially used as nutraceutical ingredients for prebiotics and anti-inflammatory agents, from soybean residue.

Polysaccharides are key bioactive compounds in lotus plumule tea, but their anti-diabetes activities remain unclear. The purpose of this study was to investigate the prebiotic activities of a novel polysaccharide fraction from the Nelumbo nucifera lotus plumule, and to examine its regulation of glucose metabolism in insulin-resistant HepG2 cells. The N. nucifera polysaccharide (NNP) was purified after discoloration, hot water extraction, ethanol precipitation, and DEAE-cellulose chromatography to obtain purified polysaccharide fractions (NNP-2). Fourier transform infrared spectroscopy was used to analyze the main structural characteristics and functional group of NNP-2. Physicochemical characterization indicated that NNP-2 had a molecular weight of 110.47 kDa and consisted of xylose, glucose, fructose, galactose, and fucose in a molar ratio of 33.4:25.7:22.0:10.5:8.1. The prebiotic activity of NNP-2 was demonstrated in vitro using Lactobacillus and Bifidobacterium. Furthermore, NNP-2 showed bioactivity against α-glucosidase (IC₅₀ = 97.32 µg/mL). High glucose-induced insulin-resistant HepG2 cells were used to study the effect of NNP-2 on glucose consumption, and the molecular mechanism of the insulin transduction pathway was studied using RT-qPCR. NNP-2 could improve insulin resistance by modulating the IRS1/PI3K/Akt pathway in insulin-resistant HepG2 cells. Our data demonstrated that the Nelumbo nucifera polysaccharides are potential sources for nutraceuticals, and we propose functional food developments from the bioactive polysaccharides of N. nucifera for the management of diabetes.

Lactobacillus strains have been considered good candidates as biological control agents for prevention or treatment of plant and animal infections. One L. plantarum strain FB003 and three strains (FB011, FB081, and FB110) which closed to L. sakei were isolated from fermented and salted shrimp and their abilities in inhibiting growth of Vibrio parahaemolyticus were characterized. These strains were selected as potential probiotics based on their oro-gastro-intestinal resistance, gut colonization, adhesion to Caco-2 cells, antimicrobial activities, antibiotic resistance, and safety aspects. Results of this study revealed that these isolates possessed high aggregation activities against pathogens in host intestines. Strain FB011 strain showed higher coaggregation and immunomodulatory activity in the gastro-intestinal tract than L. plantarum. These difference effects of Lactobacillus strains provide valuable information about using them to prevent Vibrio infections in the aquaculture industry.