Structure characterization and preliminary immune activity of a glucomannan purified from Allii Tuberosi Semen

A novel glucomannan, named ATSW-1, was obtained from Allii Tuberosi Semen by ion and gel permeation chromatography purification. Its structure was characterized using high-performance chromatography, Fourier transform infrared spectroscopy, gas chromatography-mass spectrometry, and nuclear magnetic resonance spectroscopy. The in vitro immune activities of ATSW-1 were examined using the Cell Counting Kit-8, the neutral red phagocytosis assay, and the secretion of related cytokines. The results showed that the molecular weight of ATSW-1 was 35.9 kDa and mainly constituted of mannose, glucose, and arabinose with a molar ratio of 1:0.72:0.04. Its main backbone was composed of →4)-β-D-Glcp-(1→, →4)-β-D-Manp-(1→, and →4,6)-α-D-Manp-(1→, with the branches β-D-Glcp-(1→, α-L-Araf-(1→ and →5)-α-L-Araf-(1→ linkage substituted at C-6 position of →4)-α-D-Manp-(1 → . ATSW-1 significantly enhanced immune responses, increasing the phagocytic activity of RAW264.7 cells by 1.52 times compared to the blank control group. Further investigations revealed that ATSW-1 promotes immune activity by upregulating the NO, TNF-α, and IL-6 secretion. These findings provide a foundation for the potential development and application of Allii Tuberosi Semen polysaccharides in functional foods or immune-related therapeutics.