The isolation and characterization is described of four novel cyclic polyethers, bistramides B [2], C [3], D [4], and K [5], which are closely related to the previously reported bistramide A [1] from the New Caledonian urochordata Lissoclinum bistratum. The structures of these metabolites were defined by spectroscopic methods. The four compounds exhibited in vitro cytotoxicity toward six tumor cell lines, including the human non-small cell lung carcinoma (NSCLC-N6) line. Cytofluorimetric analysis with bistramide K showed a complete block of NSCLC-N6 cells in the G1 phase. Bistramide D and particularly bistramide K are less toxic than bistramides A, B, and C and are thereby effective in vivo against NSCLC-N6.

The well-known fatty acids with a Δ5,9 unsaturation system were designated for a long period as demospongic acids, taking into account that they originally occurred in marine Demospongia sponges. However, such acids have also been observed in various marine sources with a large range of chain-lengths (C16–C32) and from some terrestrial plants with short acyl chains (C18–C19). Finally, the Δ5,9 fatty acids appear to be a particular type of non-methylene-interrupted fatty acids (NMA FAs). This article reviews the occurrence of these particular fatty acids in marine and terrestrial organisms and shows the biosynthetic connections between Δ5,9 fatty acids and other NMI FAs.

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