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 25.0 µM, while 1 and 3 possessed significant antibacterial activities against B. subtilis with MICs of 12.5 and 25.0 µM, 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).