Biological activities of new secondary metabolite produced by Streptomyces badius

Secondary metabolites obtained from Actinomycetales provide a potential source of many new antibacterial, antitumour, antifungal, antiviral, antiparasitic compounds and others. The majority of discovered substances are widely used as medicines for combating multidrug-resistant Gram-positive and Gram-negative bacterial strains, as well as in veterinary practice, agriculture and industry. Members of the Streptomyces genus are outstanding producers of already known secondary metabolites. In our study we isolated a new metabolite from Streptomyces badius fermentation broth. This compound, 2-acetamido-5-hydroxybenzoic acid (1) was already described in literature, however, not yet discovered as Streptomyces badius product. The compound was firstly isolated from fermentation broth and purified by chromatography methods (ion exchange resin DowexWX40, Solid Phase Extraction C18 Polar Plus; HPLC, dC18). Then, the chemical structure of metabolite was determined by ¹H NMR, ¹³C NMR and 2D homo- and heteronuclear (¹H-¹³C HSQC, ¹H-¹³C HMBC) NMR. The molecular formula of (1), C₉H₉NO₄ was identified by high resolution ESI-MS. The chemical structure was analyzed by the UV and IR methods, as well. Biological activities of 2-acetamido-5-hydroxybenzoic acid were evaluated. The compound shows moderate DD-peptidase 64-575 inhibitory activity as well as antioxidative properties (ABTS radical scavenging). Such chemical moiety may serve as model compound for further modern drug discovery and be a source of active substance in anti-ageing cosmetics.