New merosesquiterpenes from a Vietnamese marine sponge of Spongia sp. and their biological activities.

The investigation of the Vietnamese marine sponge Spongia sp. led to the isolation of three new sesquiterpene phenols, langconols A-C (1-3), and one new sesquiterpene hydroxyquinone, langcoquinone C (4), together with two known meroterpenoids (5 and 6). Their structures were determined on the basis of spectroscopic analyses and comparisons with published data. Furthermore, the antibacterial assays of the isolates 1-6 suggested that 4 and 6 had significant antibacterial activities against Bacillus subtilis and Staphylococcus aureus, with MICs ranging from 6.25 to 25.0µM, while 1 and 3 possessed significant antibacterial activities against B. subtilis with MICs of 12.5 and 25.0µM, respectively. In contrast, cytotoxic assays of the isolated compounds 1-6, as well as compounds 7-15 previously isolated from this sponge, indicated that 1 and the previously reported anti-B. subtilis and anti-S. aureus sesquiterpene phenol 9 lacked cytotoxic activities against three human cancer cell lines (A549, lung cancer; MCF7, breast cancer; HeLa, cervix cancer) and a human normal cell line (WI-38 fibroblast).