A novel polysaccharide from Citrus aurantium L.: Structural properties and antitumor activities in vitro and invivo

A novel cold-water-soluble polysaccharide (CALP-1-1) was isolated and purified from Citrus aurantium L. Besides determining its in vitro and in vivo anti-tumor activities, its structure was characterised. The results reveal that CALP-1-1 mainly consists of Rha, Ara, Gal, GalA, and GlcA (molar ratio, 1:14.56:19.27:2.27:1.29) with three main linkages. Its average molecular weight was 2.04 × 10³ kDa. Moreover, the triple helix structure of CALP-1-1 was proved by Congo-red and circular dichroism (CD). The in vitro experimental results demonstrate that CALP-1-1 significantly inhibited the proliferation of HepG2 cells with typical apoptotic features by inducing cell cycle arrest in the S phase. Furthermore, in vivo anti-tumor experiments suggest that CALP-1-1 could induce H22 solid tumor cells apoptosis and exhibit anti-tumor effects by protecting immune organs and intensifying the secretion of immune cells (macrophages, lymphocytes and NK cells). In conclusion, CALP-1-1 might be a promising component for cancer treatment.