Antimalarial halorosellinic acid from the marine fungus Halorosellinia oceanica

Three known compounds, 2-hexylidene-3-methylsuccinic acid (1), cytochalasin Q (2), and 5-carboxymellein (3), together with two new derivatives, 2-hexylidene-3-methylsuccinic acid 4-methyl ester (4) and an ophiobolane sesterterpene named halorosellinic acid (5), were isolated from culture broth of the marine fungus Halorosellinia oceanica BCC 5149. Compounds 1–3 exhibited moderate cytotoxicity against KB and BC-1 cell lines with IC50 values of 1–13 μg/mL, while compounds 2, 3, 5, and 6 showed antimalarial activity with respective IC50 values of 17, 4, 13, and 19 μg/mL. Halorosellinic acid (5) possessed only weak antimycobacterial activity with the minimum inhibitory concentration of 200 μg/mL.