Structural characterization and anti-tumor mechanisms of an arabinan polysaccharide isolated from Rhodiola rosea

Cancer remains a leading cause of mortality worldwide, necessitating the continuous exploration of novel therapeutic strategies. Natural polysaccharides derived from medicinal plants have emerged as a promising source of anti-cancer agents due to their diverse biological activities and generally favorable toxicity profiles. In this study, aiming to identify novel anti-tumor polysaccharides, we successfully isolated and purified a homogeneous arabinan polysaccharide, designated HJBP85-1, from Rhodiola rosea L. rhizomes using alkaline extraction and sequential chromatographic purification techniques. Comprehensive chemical characterization, utilizing techniques such as high-performance gel permeation chromatography (HPGPC), multi-angle laser light scattering (MALLS), fourier transform infrared spectroscopy (FT-IR), methylation analysis, and nuclear magnetic resonance (NMR) spectroscopy, revealed that HJBP85-1 is a highly branched arabinan, primarily composed of α-linked arabinose residues, with an average molecular weight of approximately 13 kDa. In vivo anti-tumor experiments conducted using a zebrafish xenograft model demonstrated that HJBP85-1 significantly inhibited tumor progression. Specifically, treatment with HJBP85-1 at a concentration of 400 μg/mL achieved remarkable inhibition rates of up to 93 % for tumor proliferation and 85 % for metastasis. Mechanistically, HJBP85-1 exhibited its anti-tumor effects by inhibiting tumor cell migration and angiogenesis. Furthermore, it modulated the immune response by promoting macrophage M1 polarization and inducing dendritic cell maturation and activation, as evidenced by increased nitric oxide (NO) production and the upregulation of specific surface markers. These findings highlight the promising anti-tumor properties of HJBP85-1 and strongly suggest its potential as a novel therapeutic agent for cancer treatment, thus warranting further in-depth investigation.