Fig 2.
MS/MS analyses of toxic peaks 1 (13.7 min) and 2 (15.8 min) of the semipurified methanol extracts of P. tundrae E8a (shown in Fig. 1A to C) and of similarly prepared extracts from B. cereus NS-58 (shown in Fig. 1D and E). (A) Fragment ions obtained from the precursor ion at m/z 1,171.7 of toxic peak 1 (paenilide; shown in Fig. 1A). (B) Fragmentation patterns of the b1 and b2 series mass ions from the precursor ion at m/z 1,171.5 and corresponding amino and hydroxy acid sequences of cereulide (peak at 9.7 min in Fig. 1D). (C) Fragment ions obtained from the precursor ion at m/z 1,185.5 of toxic peak 2 (paenilide homolog; shown in Fig. 1A). (D) Fragmentation patterns of the b1 and b2 series mass ions from the precursor ion at m/z 1,185.5 and corresponding amino and hydroxy acid sequences of the cereulide homolog (peak at 11.4 min in Fig. 1D). O-Val is 2-hydroxyisovaleric acid, and O-Leu is 2-hydroxyisocaproic acid.