Leukemia cells apoptosis by a newly discovered heterogeneous polysaccharide from Angelica sinensis (Oliv.) Diels

Galectin-3 (Gal-3) is a potential target for acute myeloid leukemia therapeutics which contains a carbohydrate-recognition domain. However, the development of polysaccharide inhibitors against Gal-3 is insufficient. In this research, we found a polysaccharide from Angelica sinensis (Oliv.) Diels, named APS-2I, that can bind to Gal-3 with dissociation constant (Kd) of 9.35 ± 0.3 μM and activate the intrinsic apoptosis pathways to induce leukemia cells apoptosis. APS-2I is a homogeneous polysaccharide with a molecular weight of 7.2 × 105 Da, that composes of mannose, rhamnose, galacturonic acid, glucose, galactose and arabinose with a ratio of 4:5:1:10:23:39. In addition, a galactosidase digested fraction of APS-2I named G-4 showed higher affinity to Gal-3 with the Kd of 1.97 ± 0.7 μM and higher apoptosis inducing effect on leukemia cells, which demonstrated that G-4 contains the bio-active structural region of APS-2I. This study provides effective basis for structural analysis and the anti-leukemia mechanism of Angelica polysaccharide APS-2I.