Biosynthetic capacities of actinomycetes. 4. Echinoserine, a new member of the quinoxaline group, produced by Streptomyces tendae.

A new member of the quinoxaline group antibiotics has been detected by HPLC-diode-array screening. The main compound produced by Streptomyces tendae strain Tü 4031 showed a high degree of similarity in the UV-visible spectral region with echinomycin and their structural similarity was confirmed by structure elucidation using electron tandem mass spectrometry and 2D nuclear magnetic resonance. The new compound, named echinoserine, is a non-cyclic form of echinomycin, but it is not a biosynthetic precursor. Echinoserine is less antibiotically active than echinomycin.