Abstract
Flaxseeds are widely consumed for their desirable sensory attributes and health benefits. We focused on enhancing the sustainability and economic potential of flaxseeds by characterizing functional attributes of polysaccharides isolated from flaxseed hull residues. In particular, antioxidant and immune-stimulatory polysaccharides were isolated and purified from flaxseed hull. Infrared spectroscopy was used to identify the key functional groups. The polysaccharides were composed of mannose, rhamnose, galactose, glucose, galactose, xylose, arabinose, and fucose. In vitro studies showed certain flaxseed hull polysaccharide fractions exhibited strong antioxidant activities, increased nitric oxide levels, and enhanced the production of cytokines (TNF-α and IL-6). In the presence of 200 μg/mL of one of these fractions, the levels of p-ERK, p-JNK, and p-p38 increased significantly by 1.8-, 9.0-, and 6.7-fold. These polysaccharide fractions may exhibit their immune-regulatory properties partly by modulating the MAPK pathway. The flaxseed hull polysaccharides identified have potential application as natural antioxidants and immune-enhancing nutraceuticals.
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Key Points
Polysaccharides exhibit a broad range of molecular characteristics, such as composition, molecular weight, branching, charge and polarity, depending on their biological origin. These macromolecules have attracted considerable attention from researchers in the food and pharmacological areas due to their diverse range of functional attributes, low toxicity, and high biodegradability. Cell culture models, such as the RAW264.7 model, are commonly used for the in vitro evaluation of the immune regulatory activity of bioactive compounds. In the present study, water-soluble polysaccharides were isolated from flaxseed hull and then their composition and structure were characterized using a range of chemical and biochemical methods. The antioxidant and immune regulatory activities of these polysaccharides were determined using the RAW264.7 model to establish structure–activity relationships. This study also investigated the potential mechanism of flaxseed hull polysaccharides on the MAPK immune pathway.
Flaxseed hull polysaccharides exhibited strong antioxidant and anti-inflammatory activities, at least partially attributed to its effects on the NO and MAPK pathway. The isolated flaxseed hull polysaccharides have considerable potential for utilization as natural antioxidants, anti-inflammatory health-promoting functional food