Figure 4.

Fractionation and characterization of phytocompound components of DsCE-II. (a) Anion exchange column chromatography of DsCE-II. DsCE-II fraction of D. batatas Decne was separated into seven fractions [1–7] by use of a Q Sepharose ion exchange column and eluted with 0–0.75 M NaCl salt gradient in 5 mM phosphate buffer (pH 7.0). Absorbance at 280 nm was recorded for polypeptides, and absorbance at 490 nm of each fraction was determined by use of the phenol-sulfuric acid method for the content of saccharides as described in Section 2. (b) Bioactivity assay of subfractionated components of DsCE-II. The bioactivity of each subfraction at (250 μg mL⁻¹) was measured by the murine splenocyte proliferation assay as described in Section 2. Negative control, Con A (positive control, 1 μg mL⁻¹), and the original un-fractionated DsCE-II extract (250 μg mL⁻¹) were assayed in parallel. Data represent the mean ± SD of triplicate cell culture samples. A repeated experiment showed similar results. Significant differences (***P < .001) between fractionated samples and the original un-fractionated DsCE-II.