Isolation of an unusual 2-aminoimidazolium salt of steroid trisulfate from a marine sponge Topsentia sp.

An unusual salt comprised of three 2-aminoimidazolium cations and halistanol sulfate anion was isolated from a marine sponge Topsentia sp. along with known halistanol trisodium salt. Their structures were determined by spectroscopic methods. The number of 2-aminoimidazolium ions in the molecule was estimated from the signal intensity in the H-1 NMR spectrum, and that of sodium ions was from the atomic absorption spectrometry. This is the first report of a unique salt consisted of 2-aminoimidazolium cations in natural source. Both halistanol sulfate salts showed antimicrobial activities against Flavobacterium marinotypicum and Mortierella ramaniana at 10 mu g/disk.