Chemical constituents of the red alga Laurencia tristicha

Abstract

Six new sesquiterpenes, 10-hydroxy-epiaplysin (1), 10-hydroxy-aplysin (2), 10-hydroxy-debromoepiaplysin (3), aplysin-9-ene (4), epiaplysinol (5) and debromoepiaplysinol (6), together with 13 known compounds (7–19), have been isolated from the red alga Laurencia tristicha. The structures of 1–6 were determined by spectroscopic methods including IR, EI-MS, HREI-MS, and 1D and 2D NMR techniques. All compounds were obtained from this species for the first time and were tested for cytotoxic activities against several human cancer cell lines including lung adenocarcinoma (A549), stomach cancer (BGC-823), hepatoma (Bel 7402), colon cancer (HCT-8) and HeLa cell lines. Compound 6 showed selective cytotoxicity against HeLa cell line with IC₅₀ 15.5 μM, cholest-5-en-3β,7α-diol (14) was toxic to all tested cell lines with IC₅₀ values of 16.8, 5.1, 0.5, 0.5, and 0.3 μM, respectively, and other compounds were inactive (IC₅₀>10 μg/ml).

Keywords:

• Red alga
• Laurencia tristicha
• Chemical constituents

Acknowledgements

Financial support comes from the New Century Excellent Talent (NCET) Program of Chinese Ministry of Education, the Natural Sciences Foundation of China (NSFC, Grant Nos. 30400586 and 20432030), the National “973” Program of China (Grant No. 2004CB13518906), and the Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT, Grant no. IRT0514).