Response surface methodology optimization extraction of polysaccharide from Lilium brownii F.E. Brown var. viridulum Baker/Longya Baihe and its biological activities

Lilium brownii F.E.Brown var. viridulum Baker (Longya Baihe), a traditional medicinal and edible plant. In order to study the activity of its polysaccharide extracts, a three-factor three-level Box-Behnken response surface design was employed to optimize the extraction process. The optimal extraction conditions include: liquid-solid ratio of 32:1 mL/g, extraction temperature of 70 °C, and extraction time of 3.5 h. The purified Longya Baihe polysaccharide (LP), obtained via DEAE-52 cellulose chromatography, was structurally characterized by molecular weight distribution, monosaccharide composition and infrared spectrum. The results show that LP was a macromolecular polysaccharide composed of glucose and mannose (molar ratio of 1:1.56), with an average molecular mass (Mn) of 24.006 kDa. In vitro assays demonstrated its excellent antioxidant and anti-inflammatory activities. LP significantly inhibited lipopolysaccharide (LPS)-induced activation of the nuclear factor kappa-B (NF-κB) pathway in RAW264.7 cells, downregulated the overexpression of nitric oxide (NO), interleukin (IL)-6, inducible nitric oxide synthase (iNOS) and tumor necrosis factor (TNF)-α, and enhancing the levels of the anti-inflammatory factor interleukin (IL)-10. This study suggests LP holds promise as a natural antioxidant and anti-inflammatory agent for potential development and application.