Structure and antitumor activity of a polysaccharide from Rosa roxburghii

It is proverbial that Rosa roxburghii, as a homology of medicine and food, is rich in polysaccharides. To discover bioactive macromolecules for combating cancer, the polysaccharides in R. roxburghii were investigated, leading to the purification of a polysaccharide (RRTP80–1). RRTP80–1 was measured to have an average molecular weight of 8.65 × 103 g/mol. Monosaccharide composition analysis revealed that RRTP80–1 was formed from three types of monosaccharides including arabinose, glucose, and galactose. Combination of methylation and GC–MS analysis suggested that the backbone of RRTP80–1 consisted of →5)-α-l-Araf-(1→, →6)-α-d-Glcp-(1→, →2,5)-α-l-Araf-(1→, →4,6)-β-d-Galp-(1→, and →3)-α-l-Araf-(1→, with branch chains, α-l-Araf-(1→. In vivo studies indicated that RRTP80–1 exhibited inhibitory activity against the growth and proliferation of neoplasms in the zebrafish tumor xenograft model by suppressing angiogenesis. Additionally, RRTP80–1 was found to upregulate reactive oxygen species (ROS) and nitric oxide (NO) production levels in zebrafish models. All these studies suggest that RRTP80–1 activates the immune system to inhibit tumors. The potential role of the newly discovered homogeneous polysaccharide RRTP80–1 in cancer treatment was preliminarily clarified in this study.