Discodermin-halicylindramide

Marine natural products bearing a sulfonic acid/sulfonate group are very abundant, with a huge diverse array of structures known. In most cases, this functionality is present in the discodermin-halicylindramide depsipeptides, in sulfonolipids, as well as in assorted metabolites. 

Polydiscamide A (309), discodermins A-H (298-305) and halicylindramides A-E (306-308, 310 and 311) form a series of depsipeptides composed of 13 or 14 amino acids and bear a sulfonic acid group in a cysteic acid residue, with Cys(03H), with the JV-terminus blocked by a formyl group. Their total structures, including absolute stereochemistries, were determined in most cases by a combination of spectral and chemical methods. 

The tridecapeptide polydiscamide A (309) was obtained from an unidentified Caribbean species of Discodermia [220], while discodermins A-H (298-305) were isolated from D. kiiensis. The structures deduced previously for discodermins A-E [221, 222] were later revised on the basis of NMR data and protein sequence analysis [223]. A number of closely related compounds, the tetradecapeptides halicylindramides A-C (306-308) [224], the tridecapeptide halicylindramide D (310) [225], and the truncated linear peptide halicylindramide E [225] (311) were obtained from the sponge Halichondria cylindrata. A microbial origin for these compounds was suggested [226]. 

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