CYTOTOXIC ACTIVITIES OF PHLORETHOL AND FUCOPHLORETHOL DERIVATIVES ISOLATED FROM LAMINARIACEAE ECKLONIA CAVA

Ecklonia cava (EC) is a member of the family Laminariaceae, and it is an edible marine brown alga with various bioactivities. Five phlorotannin derivatives from the methanol extract of Ecklonia cava were isolated and described as fucodiphloroethol G (1) with phenylether bridges (phlorethol), and dieckol (2), 1-(3',5'-dihydroxyphenoxy)-7-(2 '',4 '',6 ''-trihydroxyphenoxy)-2,4,9- trihydroxy-dibenzo-1,4-dioxin (3), eckol (4), and phlorofucofurofuroeckol A (5) with biaryl linkages (fucophlorethols), their structures were identified mainly by means of nuclear magnetic resonance spectral analysis. Compound 1 was obtained and characterized for the first time from this genus, and all proton resonances of 1 for phenolic hydroxyl groups were assigned completely as well, in addition, related bioactivity reports of 1 are not found anywhere so far. In this publication, cytotoxic action and future directions of these pholorotannins were evaluated first using four cultured human tumor cell lines (HeLa, HT1080, A549 and HT-29) and one cultured human normal cell line (MRC-5), with suggested explanation of the structure-activity relationship.