Anti-proliferative activity of phlorotannin extracts from brown algae Laminaria japonica Aresch

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 mu g/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 mu g/mL and > 200 mu g/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 A(2) isolated from PE by sephadex LH-20 for BEL-7402 and P388 cells at the sample concentration of 70.42 mu g/mL was 61.96 +/- 7.02% and 40.47 +/- 8.70%, respectively. The apoptosis peak for fraction A(2) 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.