Eudistalbin A was isolated from marine tunicate eudistoma album and possess cytotoxic activity (ED503.2μg/mL) in vitro against the growth of KB human buccal carinoma cells. The synthetic eudistalbin A showed potent inhibitory activity against the breast carcinoma cell line MDA-231 with an IC50 value of 2.1 μmol/L using the metabolic assay MTT. All structures of new compounds were confirmed by 1H NMR, 13C NMR, HRMS and optical rotation.