Structure and anticancer activity of sulfated O-polysaccharide from marine bacterium Cobetia litoralis KMM 3880 T

The immunostimulatory activity of sea spray aerosols: bacteria and endotoxins activate TLR4, TLR2/6, NF-κB and IRF in human cells

Frequent exposure to sea spray aerosols (SSA) containing marine microorganisms and bioactive compounds may influence human health. However, little is known about potential immunostimulation by SSA exposure. This study focuses on the effects of marine bacteria and endotoxins in SSA on several receptors and transcription factors known to play a key role in the human innate immune system. SSA samples were collected in the field (Ostend, Belgium) or generated in the lab using a marine aerosol reference tank (MART). Samples were characterized by their sodium contents, total bacterial counts, and endotoxin concentrations. Human reporter cells were exposed to SSA to investigate the activation of toll-like receptor 4 (TLR4) in HEK-Blue hTLR4 cells and TLR2/6 in HEK-Blue hTLR2/6 cells, as well as the activation of nuclear factor kappa B (NF-κB) and interferon regulatory factors (IRF) in THP1-Dual monocytes. These responses were then correlated to the total bacterial counts and endotoxin concentrations to explore dose-effect relationships. Field SSA contained from 3.0 × 103 to 6.0 × 105 bacteria/m3 air (averaging 2.0 ± 1.9 × 105 bacteria/m3 air) and an endotoxin concentration ranging from 7 to 1217 EU/m3 air (averaging 389 ± 434 EU/m3 air). In contrast, MART SSA exhibited elevated levels of total bacterial count (from 2.0 × 105 to 2.4 × 106, averaging 7.3 ± 5.5 × 105 cells/m3 air) and endotoxin concentration from 536 to 2191 (averaging 1310 ± 513 EU/m3 air). SSA samples differentially activated TLR4, TLR2/6, NF-κB and IRF. These immune responses correlated dose-dependently with the total bacterial counts, endotoxin levels, or both. This study sheds light on the immunostimulatory potential of SSA and its underlying mechanisms, highlighting the need for further research to deepen our understanding of the health implications of SSA exposure.

Structural Modification and Biological Activity of Polysaccharides

Natural polysaccharides are macromolecular substances with a wide range of biological activities. The structural modification of polysaccharides by chemical means can enhance their biological activity. This paper reviews the latest research reports on the chemical modification of natural polysaccharides. At present, the modification methods of polysaccharides mainly include sulfation, phosphorylation, carboxymethylation, socialization, methylation and acetylation. The chemical and physical structures of the modified polysaccharides were detected via ultraviolet spectroscopy, FT-IR, high-performance liquid chromatography, ultraviolet spectroscopy, gas chromatography-mass spectrometry, nuclear magnetic resonance and scanning electron microscopy. Modern pharmacological studies have shown that the modified polysaccharide has various biological activities, such as antioxidant, antitumor, immune regulation, antiviral, antibacterial and anticoagulant functions in vitro. This review provides fresh ideas for the research and application of polysaccharide structure modification.

Chemical structure and antioxidant activity of a polysaccharide from Siraitia grosvenorii

A novel polysaccharide from Siraitia grosvenorii residues (SGP, molecular weight 1.93 × 10³ KDa) was isolated and purified. SGP was composed of α-L-Arabinose, α-D-Mannose, α-d-Glucose, α-D-Galactose, Glucuronic acid, and Galacturonic acid with the ratio of 1: 1.92: 3.98: 7.63: 1.85: 7.34. The backbone of SGP was consist of galactoses and linked by α-(1,4)-glycosidic bond. The branch chains including α-1,6 linked glucose branch, α-1,6 linked mannose branch, α-1,3 linked galactose branch and arabinose branched (α-L-Ara(1→). The results of bioactivity experiments suggested that SGP had antioxidant in vitro, especially on scavenging DPPH radicals. Besides, SGP resulted in the decrease of ROS and the percentage of apoptotic and necrotic cells in a dose-dependent manner in H₂O₂ oxide injury PC12 cells. This research could help to develop the potential value and utilization of Siraitia grosvenorii.

Purification, characterization and anticancer activities of exopolysaccharide produced by Rhodococcus erythropolis HX-2

In the present study, an exopolysaccharide (EPS) producer Rhodococcus erythropolis HX-2 was isolated from Xinjiang oil field, China. The HX-2 EPS (name HPS) production reached 8.957 g/L by RSM in MSM medium. The HPS was purified by ethanol precipitation and fractionation by DEAE-Cellulose and Sepharose column, the yield of HPS was 3.736 g/L. HPS composed by glucose, galactose, fucose, mannose and glucuronic acid. FT-IR spectroscopy indicated the presence of a large amount of hydroxyl groups. NMR spectroscopy indicated the existence of both α and β-configuration for sugar moieties present in HPS. The degradation temperature (255.4 °C) of the HPS was determined by thermogravimetric analysis (TGA). A reticular structure of HPS was observed by SEM and the AFM analysis of the HPS revealed straight chains line. Meanwhile, the WSI and WHC of HPS were 92.15 ± 3.05% and 189.45 ± 5.65%, respectively. Finally, In vitro anticancer activity purified EPS was evaluated on L929 normal cells, A549 cancer cells, SMMC-7721 liver cancer cells and Hela cervical cancer cell. HPS inhibited the growth of cancer cells in a certain concentration without damage to normal cells. These characteristics indicate that its potential application value in food, industry and pharmaceutical application.

Inhibitory Effect of Depolymerized Sulfated Galactans from Marine Red Algae on the Growth and Adhesion of Diarrheagenic Escherichia coli

Active polysaccharides as safe and natural polymers against bacterial diarrhea have been reconsidered as an alternative to antibiotics. This work investigated the inhibiting effect of depolymerized sulfated galactans from Eucheuma serra and Gracilaria verrucosa on the growth and adhesion of diarrheagenic enterotoxigenic Escherichia coli (ETEC) K88. Results showed that the sulfated polysaccharides with molecular weight distribution ≤20.0 kDa exhibited antibacterial activity against ETEC K88. A structure-activity study revealed that the anti-ETEC K88 activity of sulfated polysaccharides is strictly determined by their molecular weight distribution, sulfate group content, and monosaccharide composition. In addition, the promoted nucleic acid release and the fluorescence quenching of membrane proteins were observed after the treatment with selected polysaccharides. Scanning electron microscopy further confirmed that the depolymerized sulfated galactans can effectively inhibit ETEC K88 adhesion. In conclusion, depolymerized sulfated galactans exhibited an inhibitory effect on the growth and adhesion of ETEC K88.

Natural products and morphogenic activity of γ-Proteobacteria associated with the marine hydroid polyp Hydractinia echinata

Illumina 16S rRNA gene sequencing was used to profile the associated bacterial community of the marine hydroid Hydractinia echinata, a long-standing model system in developmental biology. 56 associated bacteria were isolated and evaluated for their antimicrobial activity. Three strains were selected for further in-depth chemical analysis leading to the identification of 17 natural products. Several γ-Proteobacteria were found to induce settlement of the motile larvae, but only six isolates induced the metamorphosis to the primary polyp stage within 24h. Our study paves the way to better understand how bacterial partners contribute to protection, homeostasis and propagation of the hydroid polyp.