(E)-4-Oxonon-2-enoic Acid, an Antibiotically Active Fatty Acid Produced by Streptomyces olivaceus Tue 4018.

Streptomyces olivaceus Tii 4018 was included in our screening programme for detection and isolation of new secondary metabolites. Extracts of actinomycete strains were analysed by HPLC coupled with diode array multiwavelength monitoring (HPLC-DAD)and a UVvisible absorbance spectral library database2). The kanchanamycins, a complex of new 36-membered polyol-type macrolide antibiotics1)3), the 42-membered macrolactones desertomycin A4) and oasomycin A5), and tryptophan-dehydrobutyrine diketopiperazine6) as well as the isoflavone daidzein were isolated from strain Tii 401 8. All metabolites were produced during fermentation in a complex mediumconsisting of 2% mannitol and 2% soybean meal. In addition to these compounds, S. olivaceus Tii 4018 produced under modified cultivation conditions a substance which was detected in the myceliumextract by HPLC-DADanalysis (HP 1090M liquid chromatograph equipped with a built-in diode array detector and HPLC3D-ChemStation, Hewlett-Packard). This compound was not identified by spectral matching techniques using our HPLC-DADdatabase. HPLC-ESI-MS analysis (ABI 140A HPLC system, Applied Biosystems; API III triple-quadrupol mass spectrometer equipped with a nebulizer-assisted electrospray ion source, Sciex) determined a molecular mass of 170.1, and search in commercially available databases lead to further evidence for the novelty as a natural product. Isolation and structure elucidation resulted in determination of the compound as (£)-4-oxonon-2-enoic acid (Fig. 1) that