Thorectopsamma xana

There have been three reports of the same dimeric disulfide. It was first isolated from an unidentified sponge from Guam and the structure elucidated by analysis of spectral data. The (E,E) stereochemistry of the disulfide (500) was defined by comparing the I3C NMR spectroscopic data with those of the (E,Z)-isomer (501) that was obtained as an unstable minor product [425]. Compound 500 was isolated from a species of Psammaplysilla and was called psammaplin A [426]. It was also isolated from Thorectopsamma xana, collected from the same location in Guam, together with a minor dimeric metabolite bisaprasin (502). Both compounds inhibited growth of Staphylococcus aureus and Bacillus subtilis [427]. Psammaplin A (bisprasin) (500) was later isolated from a Dysidea species of sponge and shown to act on Ca2+-induced Ca2+ release channels of skeletal muscle [428]. 

Thorectopsamma xana Poecillastra sp. / Jaspis sp. association Aplysinella rhax Pseudoceratina purpurea... 

Scheuer et al. later reported the psammaplin A (152) and the psammaplin A dimer, bisaprasin (154), from the Guam sponge Thorectopsamma xana (109). 

---