Three new hydroxylated rhamnolipids, dokdolipids A-C (1-3) were obtained from the marine actinomycete Actinoalloteichus hymeniacidonis, which was isolated from a sediment sample collected off the coasts of Dokdo island, Republic of Korea. The structures of the isolated compounds were elucidated on the basis of 1D and 2D NMR and mass spectrometric data analyses. Their absolute configurations were assigned using the modified Mosher's method and specific rotation values, as well as acid hydrolysis, chemical derivatizations and subsequent HPLC analysis to determine the configuration of the sugar moieties. All new compounds were evaluated for their cytotoxicity against six cancer cell lines, HCT-15, NUGC-3, NCI-H23, ACHN, PC-3 and MDA-MB-231. Compounds 1-3 displayed moderate cytotoxicity against all the cell lines tested with IC50 values ranging from 13.7-41.5 µM.
Keywords: Actinoalloteichus hymeniacidonis; biosurfactants; cytotoxicity; rhamnolipids; rhamnose.