Alginate oligomer induces nitric oxide (NO) production in RAW264.7 cells: elucidation of the underlying intracellular signaling mechanism

Abstract

Alginate is an acidic linear polysaccharide with immune-modulating activities. In this study, we found that enzymatically digested alginate oligomer (AO) with various degrees of polymerization (DP; 2–5) induced a higher level of nitric oxide (NO) production in RAW264.7 cells than undigested alginate polymer (AP). Reverse transcription-polymerase chain reaction and western blot analyses revealed that the expression level of inducible NO synthase in AO-treated RAW264.7 cells was higher than that in AP-treated cells. AO induced nuclear translocation of nuclear factor (NF)-κB p65 subunit in RAW264.7 cells to a greater extent than AP. Although AO and AP induced similar extents of phosphorylation in three mitogen-activated protein (MAP) kinases, c-Jun N-terminal kinase inhibitor exhibited the most potent inhibitory effect on NO induction in AO- and AP-treated RAW264.7 cells, among three MAP kinase inhibitors that were tested.

The effects of alginate lyase treatment on structural characteristics and anti‐photoaging activity of alginate from Sargassum fusiforme

“…(2019). Another study also showed that enzymatically prepared alginate with specific molecular showed good immunomodulatory activity (Ueno et al., 2015). The biological activity of polysaccharides depends on their structural characteristics (Yang et al., 2021).…”

“…Samples with a hydrolysis time of 30 min showed significant inhibition, indicating that proper degradation was helpful to improve the bioactivity of polysaccharides, which was in line with the study reported by Dou et al (2019). Another study also showed that enzymatically prepared alginate with specific molecular showed good immunomodulatory activity (Ueno et al, 2015). The biological activity of polysaccharides depends on their structural characteristics (Yang et al, 2021).…”

Brown Algae Carbohydrates: Structures, Pharmaceutical Properties, and Research Challenges

“…AOSs can also induce the production of nitric oxide (NO) by increasing the expression of NO synthase in cells. NO is a multifunctional molecule that can act as a vasodilator, neurotransmitter, inflammatory mediator, and specific immunomodulator [60]. The immunomodulatory activity of AOSs is affected by many factors, e.g., degree of polymerization, purity, M/G ratio, and MG sequence.…”

Alginate Oligosaccharides: Production, Biological Activities, and Potential Applications

“…When intraperitoneally administrated, AOS (700 mg/kg) prepared by enzymatic digestion stimulated production of 20 cytokines with granulocyte CSF, monocyte chemoattractant protein‐1, IL‐6, keratinocyte‐derived chemokine, and IL‐12, and regulated upon activation of normal T cell expressed and secreted reaching >5,000 pg/mL in serum (Yamamoto, Kurachi, Yamaguchi, & Oda, ). Enzymatically prepared AOS (DP 2 to 5) induced production of nitric oxide (NO), a multifunctional molecule that acts as a vascular relaxing agent, neurotransmitter, inflammatory mediator, and specific immunity regulator, through elevated expression of NO synthase in RAW264.7 cells (Ueno et al., ). Researches on immunomodulatory activity of AOS were majorly performed with in vitro models, whereas the exact effects of AOS on immune responses in vivo should be well explained in details.…”