| Abstract
| - Pseudoceratins A (1) and B (2) have been isolated from the marine sponge Pseudoceratina purpurea.Pseudoceratins are unique among the large class of bromotyrosine-derived sponge metabolites with respectto the substitution pattern of aromatic rings and the presence of spiroacetal and oxime ether functionalgroups as well as an 1,5-diamino-1,5-dideoxy-D-arabitol tether. Pseudoceratins A (1) and B (2) are epimericdiffering in the orientation of the tether. Their structures were determined by analysis of spectral data.The rigidity of the compounds arising from their bridged structure gave ROESY/NOESY spectra withmany transannular cross-peaks, which allowed the assignment of the relative stereochemistry of 1 and 2to be established. The d-configuration of the 1,5-diamino-1,5-dideoxyarabitol unit was determined byconverting the fragment isolated from the acid hydrolysate to the Mosher's ester and compared the 1HNMR spectrum with those of standard samples. Pseudoceratins exhibited significant antifungal activityagainst Candida albicans.
|
