Growth Inhibition of Carcinoma Cells by Sodium Alginate from Petalonia Binghamiae (Phaeophyceae)

Abstract

Alginate is an important structural component of brown algae and has various biological activities. In addition, the polymer has high affinity for binding divalent metal ions, leading to change in molecular conformation. In the present study, sodium alginate extracted from the brown alga Petalonia binghamiae inhibited markedly the proliferation in human pancreatic and breast adenocarcinoma cells. The inhibitory activity of alginate decreased after being treated with citrate buffer solution and lost in the presence of Ca^2+, Zn^2+, Co^2+ or Mn^2+. However, alginate remained high inhibitory activity if metal ions were treated with Na2EDTA prior to addition to culture medium. These results suggested that ion exchange at carboxyl groups as well as molecule conformation of the polymer played an important role in alginate inhibitory reaction with carcinoma cells. Notably, the obtained alginate induced murine macrophages to produce proteinaeous substance that significantly inhibited carcinoma cell proliferation. Our study suggests that sodium alginate has potent use in anticancer therapy and research due to its wide distribution and high production in marine brown algae.