Antioxidant and antiproliferative activities of extracts from a variety of edible seaweeds

Dietary Laminaria and Porphyra sp. have been reported to reduce the risk of intestinal or mammary cancer in animal studies. Algal anticarcinogenicity may involve effects on cell proliferation and antioxidant activity. Thus, in the present study, we evaluated the effect of red alga, dulse (Palmaria palmata) and three kelp (Laminaria setchellii, Macrocystis integrifolia, Nereocystis leutkeana) extracts on human cervical adenocarcinoma cell line (HeLa cells) proliferation using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay. The 1-butanol soluble fractions from the methanol extracts of these algae were also evaluated for reducing activity and total polyphenol content. After 72 h incubation, HeLa cell proliferation was inhibited (p < 0.05) between 0% and 78% by P. palmata; 0% and 55% by L. setchellii and 0% and 69% by M. integrifolia and N. leutkeana at 0.5–5 mg/mL algal extract. Algal extract reducing activities were as follows: P. palmata > M. integrifolia > L. setchellii > N. leutkeana; and total polyphenol contents were: P. palmata > M. integrifolia = N. leutkeana > L. setchellii. The antiproliferative efficacy of these algal extracts were positively correlated with the total polyphenol contents (p < 0.05), suggesting a causal link related to extract content of kelp phlorotannins and dulse polyphenols including mycosporine-like amino acids and phenolic acids.