Isolation, purification, structural characterization and antitumor activities of a polysaccharide from Lilium davidii var. unicolor Cotton

The water-soluble polysaccharide from Lilium davidii var. unicolor Cotton (LP60-1) was extracted by hot water, precipitated by fractional alcohol, separated by DEAE Sepharose Fast Flow column and purified though Sephacryl S-400 HR. The HPGPC result showed LP60-1 was a homogeneous polysaccharide with the MW of 6.5 × 103 Da. LP60-1 was composed of mannose and glucose with the ratio of 1.26: 1. Methylation and NMR analysis showed that the backbone of LP60-1 was consisted of β-(1→4)-linked mannose residues and β-(1→4)-linked glucose residues. And the substitution site of acetyl groups was O-2 or O-3 of mannose and the degree of acetylation was 0.2. In addition, the higher structure of LP60-1 has been preliminarily explored through CD, SEM, and AFM. LP60-1 had obvious anti-tumor activity, and the inhibition rate of HepG2 cell was 81.45% (IC50 = 123.8 µg/mL). The results proposed that LP60-1 can be researched and developed as a new antitumor drug.