Antitumor activities of different fractions of polysaccharide purified from Ornithogalum caudatum Ait

Four water-soluble polysaccharide fractions (OCAP-2-1, OCAP-2-2, OCAP-3-1 and OCAP-3-3) extracted from the Ornithogalum caudatum Ait, were obtained by DEAE fast flow Sepharose anion-exchange, and Sephadex G-75 gel-permeation chromatography. The monosaccharide components of four polysaccharides were characterized by gas chromatography (GC), and the majority of the monosaccharide components were glucose (30–42.5%) and galactose (23–29%), with low levels of arabinose (6–14%), mannose (2–9%), xylose (4–6%), glucuronic acid (1.0–7.5%), galactose acid (1–6%). The high-performance gel-permeation chromatography (HPGPC) analysis showed that the average molecular weight (Mw) of four polysaccharides were approximately 102.1, 62.3, 46.4 and 22.8 KDa, respectively. The protein contents of four fractions were 2.13%, 2.82%, 3.45% and 3.97%, respectively. All polysaccharide fractions exhibited significantly higher antitumor activity against solid tumor Sarcoma 180 in vivo than did a blank control. Fractions OCAP-2-2, OCAP-3-1 and OCAP-3-2 significantly inhibited the growth of K562 cells in vitro. Results of these studies demonstrated that the polysaccharide had a potential application as natural antitumor drugs.