Purpuramine R, a New Bromotyrosine Isolated from cf. Collected in the Kingdom of Tonga.

Sponges in the verongiid genus Carter are well-known producers of bioactive secondary metabolites. Chemical screening of a Tongan cf. Bergquist using NMR highlighted the presence of aromatic natural products. Subsequent extraction and purification of cf. yielded a new bromotyrosine, purpuramine R (), that exhibits moderate (MIC 16 µg/mL) antibacterial activity against Gram-positive The -geometry of the oxime was confirmed using a combination of NMR and computational approaches. Additionally, computational conformational analysis indicates that purpuramine R adopts a hairpin orientation, stabilized by intramolecular hydrogen and halogen bonds. Knowledge of this stabilized conformation can inform synthetic approaches to make analogues of the purpuramines for future SAR studies.