Figure 3.

Aromatic amino acids and signal pCA serve as roseobacticide precursors. (A) Assigned ¹H NMR spectrum of roseobacticide C. (B) ¹H spectrum of roseobacticide C isolated from cultures containing ring-²H₅-Trp, showing incorporation of ²H₅-indole. (C) HR-MS spectrum of roseobacticide A isolated from cultures containing ring-²H₄-Tyr. Both protonated and ²H₄-phenol-bearing isotopomers are observed. (D) HR-MS spectrum of roseobacticide B isolated from cultures containing ring-²H₅-Phe. Three deuterated isotopomers and the all-protonated form are observed. (E) HR-MS spectrum of roseobacticide A isolated from cultures containing 2-¹³C-pCA showing incorporation of signal pCA into roseobacticide A; see Scheme 2 and Table S1.