Eudistomins W and X, Two New β-Carbolines from the Micronesian Tunicate Eudistoma sp.

Chemical investigation of the Micronesian ascidian Eudistoma sp. afforded two new eudistomin congeners, which were designated eudistomins W (1) and X (2). The structures of the new compounds were unambiguously established on the basis of NMR spectroscopic ((1)H, (13)C, COSY, (1)H detected direct, and long-range (13)C-(1)H correlations) and mass spectrometric (EI and ESIMS) data. Compound 2 exhibited antibiotic activity toward Bacillus subtilis, Staphyloccocus aureus, and Escherichia coli and was also found to be fungicidal against Candida albicans in an agar diffusion assay. Compound 1 was selectively active against C. albicans but showed no antibacterial activity.