The potential antiproliferative and antiradical activities of an enzymatic extract of Ecklonia cava together with its crude polysaccharide (CpoF) and crude polyphenolic fractions (CphF) were evaluated in vitro. Tested extracts showed strong selective cell proliferation inhibition on all cancer cell lines tested, especially CphF extract, containing high polyphenol amount, showed 5.1 microg/ml of IC(50) value on murine colon cancer (CT-26) cell line. According to the nuclear staining experiment, antiproliferative effect of CphF was associated with apoptotic cell demise in CT-26. In addition, The CphF at 5 microg/ml scavenged 70% of DPPH radical, which is much higher than those of BHA and BHT at same concentration. Further more CphF exhibited interesting antiradical properties, expressed by its capacity to scavenge superoxide anion (O(2)(-)), hydrogen peroxide (H(2)O(2)) and hydroxyl radical (OH()). In reducing power assay, CphF extract at 5 microg/ml was found to be as high as that of BHT at same concentration. Also, in total antioxidant assay the effect of CphF at 50 microg/ml was equivalent or slightly higher than those of commercial counterparts at 5 microg/ml concentration. Taken together, the CphF may be a promising alternative to synthetic substances as natural compound with high antiproliferative and antiradical activity.