Constituents from Ircinia echinata and their Antiproliferative Effect on Six Human Cancer Cell Strains

Background: Marine sponges have produced a large number of secondary metabolites and become a potent source of anti-cancer agents for drugs discovery. Screening results indicated that methanol extract of the sponge Ircinia echinata significantly induced in vitro antiproliferative effect against human cancer cell strains HepG-2, KB, and MCF-7. Therefore, this study aims to isolate, identify chemical structure, and evaluate antiproliferative activity of constituents from the sponge I. echinata. Methods: Frozen samples of the sponge I. echinata were ultrasonically extracted in methanol. The methanol extract was fractionated and purified using chromatographic methods to obtain pure compounds. Chemical structures of isolated compounds were elucidated by HR-ESI-MS, 1D-, 2D-NMR spectral data, and as well as comparison with reported literature. In addition, antiproliferative effects of isolated compounds on six human cancer cell strains (HepG-2, HL-60, KB, LU-1, MCF-7, and LNCaP) were evaluated by Sulforhodamine B assay. Results: A new furanosesterterpene, 8-hydroxyisovariabilin (1), together with eleven known ones, including four furanoterpenes (2-5), a fatty acid (6), and six sterols (7-12) were isolated from methanol extract of the sponge I. echinata. Antiproliferative evaluation revealed that furanosesterterpene 3 and sterols 7, 9-12 are promising anticancer agents. Among them, sterols 11 and 12 exhibited anti-proliferative effect on tested cancer cell strains with IC50 values in range of 4.53-9.74 μg/mL. Conclusion: The sponge I. echinata found at the sea of Vietnam is a good source for the isolation of furanoterpenoids and sterols. Isolated furanosterterpene (3) and sterols (7, 9-12) are promising antiproliferative agents which could be useful in anticancer drugs discovery.