Abstract: An in vitro immune cell model was used for bioactivity-guided fractionation of the crude polysaccharides ultrasonically extracted from Haematococcus pluvialis residue left after the extraction of astaxanthin by sequential DEAE-52 anion exchange and Sephacryl S400 column chromatographies. The molecular masses of the isolated polysaccharides were determined by high performance gel permeation chromatography (HPGPC). The results showed that five polysaccharides, named HPP-c1, HPP-c2, HPP-c3, HPP-c4 and HPP-c5, were obtained by DEAE-52 column chromatography. Of these, HPP-c3 had the highest immunological activity. Further, HPP-c3-s1, HPP-c3-s2, and HPP-c3-s3 were isolated from HPP-c3 by Sephacryl S400 column chromatography. HPP-c3-s1 could significantly stimulate the proliferation of spleen cells (P < 0.01) in the concentration range of 0–250 μg/mL in a dose-dependent fashion. HPP-c3-s1 had the highest stimulation index (SI) of 1.34 among the HPP-c3 fractions. The purity of HPP-c3-s1 was found to be homologous with a molecular mass of 23 413 kDa. These results provide a valuable guidance for the high-value comprehensive utilization of H. pluvialis.

Key words: Haematococcus pluvialis, polysaccharide, isolation and purification, immunological activity