Hydrated Rubrolides from the New Zealand Tunicate Synoicum kuranui

LCMS analysis of an extract of the New Zealand tunicate Synoicum kuranui showed evidence for numerous new rubrolides. Following a mass spectrometry-guided isolation procedure, new hydrated rubrolides V and W (5 and 6), along with previously reported rubrolide G (3), were isolated and characterized using MS and NMR. The anti-bacterial and cell cytotoxic activity of the compounds were compared to the potent anti-MRSA compound rubrolide A; hydration across the C-5/C-6 bond was shown to abrogate antibacterial activity.