In this study,we evaluated the anti-proliferative activity of phlorotannins derived from brown algae Laminaria japonica Aresch extracts on the human hepatocellular carcinoma cell (BEL-7402) and on murine leukemic cells (P388) by MTT assay.Cells were incubated with 100 μg/mL of the phlorotannin extract (PE) for 48 h.The inhibitory rate of PE on BEL-7402 and P388 cells was 30.20±1.16% and 43.44±1.86%,respectively,and the half-inhibitory concentration of PE (IC50) on P388 and BEL-7402 cells was 120 μg/mL and >200 μg/mL,respectively.Microscopic observation shows that the morphologic features of tumor cells treated with PE and 5-fluorouracil are markedly different from the normal control group.The inhibitory rate of fraction A2 isolated from PE by sephadex LH-20 for BEL-7402 and P388 cells at the sample concentration of 70.42 μg/mL was 61.96±7.02% and 40.47±8.70%,respectively.The apoptosis peak for fraction A2 was the most profound of all fractions used in the flow cytometry assay.The results indicate that the anti-proliferative of this algal extract is associated with the total phlorotannin content.
