Biosurfactants from Marine Cyanobacteria Collected in Sabah, Malaysia.

Chemical investigation of the organic extract from , collected in Sabah, Malaysia, led to the isolation of three new chlorinated fatty acid amides, columbamides F (), G (), and H (). The planar structures of - were established by a combination of mass spectrometric and NMR spectroscopic analyses. The absolute configuration of was determined by Marfey's analysis of its hydrolysate and chiral-phase HPLC analysis after conversion and esterification with Ohrui's acid, (1,2)-2-(anthracene-2,3-dicarboximido)cyclohexanecarboxylic acid. Compound showed biosurfactant activity by an oil displacement assay. Related known fatty acid amides columbamide D and serinolamide C exhibited biosurfactant activity with critical micelle concentrations of about 0.34 and 0.78 mM, respectively.