Sesquiterpene components of Laurencia tristicha

Objective To search for sesquiterpene components with structural diversity from Laurencia tristicha to supply for pharmacological activity screen. Methods Compounds were isolated by means of column chromatography over normal phase silica gel and Sephadex LH-20, recrystallization, and HPLC. Structures were identified by spectroscopic methods including 1D and 2D NMR, IR, X-ray, and MS. Cytotoxicities of the purified compounds were evaluated by MTT method. Results Five sesquiterpenes, aplysin (Ⅰ), aplysinol (Ⅱ), debromoaplysinol (Ⅲ), laurebiphenyl (Ⅳ), and johnstonol (Ⅴ) have been isolated and identified. In the cytotoxic assay compound Ⅳ was active against human cancer cell lines, HCT-8, Bel-7402, BGc-823, A549, and HeLa with IC_ 50 values of 1.77, 1.91, 1.22, 1.68, and 1.61 μg/mL, respectively. Compound Ⅲ showed cytotoxicity against HeLa with IC_ 50 value of 3.6 μg/mL while other compounds were inactive (IC_ 50 10 μg/mL). Conclusion Compounds Ⅰ-Ⅴ are isolated from L. tristicha for the first time. Compound Ⅲ shows moderate selective cytotoxicity against HeLa cell line and compound Ⅳ is cytotoxicity against several human cancer cell lines.