Structural characteristics of polysaccharides from <i>Neolitsea cassia</i> (L.) Kosterm. residue extracted by alkali and their immunomodulatory effects on RAW 264.7 cells

<i>Neolitsea cassia</i> (L.) Kosterm., also known as cinnamon, is a medicinal and edible plant whose bark possesses pharmacological activities. Two active acidic polysaccharides were extracted from the plant by alkali and then purified. ACP-1F (776.01 kDa), predominantly composed of glucuronic acid, galacturonic acid, glucose, galactose, and arabinose, but galacturonic acid was not detected in ACP-2F (98.56 kDa). The primary structural characteristics of two polysaccharides was investigated through a combination of analytical methods. The triple-helix structure and branching structure analysis were also conducted. The ACP-1F and ACP-2F exhibited divergent free radical scavenging capacities. Subsequent analysis revealed their capacity to stimulate nitric oxide secretion, augment phagocytic activity in RAW 264.7 cells, and enhance immune stress activity in RAW 264.7 macrophages. These findings establish a foundation for the potential use of ACP-1F and ACP-2F as immunomodulators, providing substantiated data in support of the efficacy of alkaline‑extracted polysaccharides derived from traditional Chinese medicinal materials.