Tetrapeptides Possessing a Unique Skeleton, JBIR-34 and JBIR-35, Isolated from a Sponge-Derived Actinomycete, Streptomyces sp Sp080513GE-23

Two new modified indole-containing peptides, JBIR-34 (1) and JBIR-35 (2), were isolated from the fermentation broth of a sponge-derived actinomycete identified by phylogenetic methods as a Streptomyces sp. (strain Sp080513GE-23). The planar structures of 1 and 2 were assigned on the basis of I D and 2D NMR spectroscopy and MS analyses. Further, the absolute configurations of the amino acid residues were determined using Marfey's method.