Polysaccharide content in protein-polysaccharides (PPS) extracted from sea mustard, sea tangle and fusiform were 40.61, 38.42 and 52.80% , respectively. 5% of sea tangle PPS showed highest inhibitory activity on 4-nitorquinoline -1-oxide(4-NQO) against Salmonella typhimurium TA100 compared to the other seaweed PPS. 5% of sea mustard PPS showed highest inhibition ration of 62% on 2-nitrofluorene(2-NF)against Salmonella typhimurium TA98. These PPS extracts showed cytotoxic activity against human colon cancer cell (SW-480), and showed mild cytotoxic activity on human stomach cancer cell(SNU-1) and human hepatic cancer cell(HepG 2).